Drainage basin

As inundações são processos naturais essenciais à dinâmica fluvial as quais influenciam atividade humana e sua ocupação espacial (MACKLIN; LEWIN, 2015). Nas últimas décadas em função do aumento populacional e surgimento de ocupações inapropriadas, ou seja, próximo ás várzeas de inundação, o número de pessoas afetadas e os prejuízos econômicos em função das inundações têm aumentado de forma significativa (GOERL; MICHEL; KOBIYAMA, 2017). A combinação entre crescimento populacional e falta de investimentos em planejamento e infraestrutura para amenizar os efeitos das inundações, deixam a população em áreas vulneráveis aos efeitos destes eventos extremos. Neste contexto, para amenizar os efeitos das cheias e inundações surgem às medidas chamadas não estruturais, dentre elas destaca-se o mapeamento de áreas de risco, simulações e previsões hidrológicas através de modelos hidrológicos, estações telemétricas, além de Sistemas de Alerta de Cheia (SAC). Visando compor hidrogramas de saída de modelos hidrológicos, bem como hidrogramas de estações fluviométricas para que sejam entendidos por técnicos e demais usuários, surge à demanda de metodologias para estimativa e validação de limares de inundação, representando o valor aproximado de vazão ou de nível em que o rio extrapola seu leito maior em determinado ponto. Neste contexto, o objetivo deste trabalho é estudar uma metodologia de estimativa e validação de limiares de inundação a partir de imagens de satélite, considerando as bacias dos rios Caí e Sinos no Rio. Para validação da metodologia proposta, buscou-se rios com estações telemétricas com dados de limiares de inundação já validados em campo, como é o caso do rio Caí e do Sinos, os quais possuem nas estações Barca do Caí (87170000) e Passo Montenegro (87270000)no Caí valores consolidados de limiares de inundação validados pelo Serviço Geológico do Brasil -CPRM e no Sinos na estação Campo Bom (87380000), limiares consolidados pela Sala de Situação da SEMA-RS, além da estação São Leopoldo (87382000) a qual ainda não possui limiares de inundação consolidados. Todas estas estações mencionadas são operadas pela CPRM e possuem dados históricos a mais de 50 anos, possibilitando o estimar valores dos níveis e vazões de permanência, assim como de tempos de retorno das cheias neste rio. O download dos dados das séries histórica das estações mencionadas foi realizado através do site . Os dados diários de nível foram organizados para que fossem calculadas as permanências de cada nível e seu respectivo tempo de retorno para as estações, correlacionando com os valores dos limiares de inundação de 1000cm para a estação Barca do Caí, 600cm para a estação Passo do Montenegro e 550cm para a estação Campo Bom. Nas estações consideradas para o Rio Caí, as cotas de inundação mencionadas correspondem a um tempo de retorno de 1,2 anos. Já na estação Campo Bom, o período de retorno para a cota de inundação considerada o tempo retorno calculado foi de 1,1 anos. Para a estação São Leopoldo, buscou-se a cota de inundação referente a um tempo de retorno de 1,1 anos: 350cm. Posteriormente foram buscadas imagens dos satélites Sentinel e Landsat 8 em dias que o nível dos rios Caí e Sinos tenham ultrapassado os limiares nas estações consideradas no período de 2013 a 2018. Deste modo foi possível baixar 4 imagens através do site referentes aos dias:

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A recent work carried out by CREA (ex INEA) compared spatial analysis of the main problems concerning the use of water resources for irrigation in Italian River basin districts (RBD) with the policy measures for water resources and agriculture, in order to verify the relevance of planning to address specific regional sensitivities. The bases for the policy analysis was River basin management plans (RBMPs), in updating, and proposal of Regulation for rural development, not yet approved at the time. The spatial and statistical analysis was done, for each Italian RBD, through cluster analysis method using specific indicators, calculated using quantifiable and comparable public database (ISTAT, ISPRA, SIGRIAN) and representing qualitative and quantitative pressures on waters and environmental constraint. The aim of this work is the updating of spatial analysis, with reference to recently approved RBMPs and new regional RDPs 2014-2020, based on the Regulation for rural development 1305/2...

Estudiar las alteraciones en la oferta hídrica asociadas a la variabilidad o al cambio climático, es importante para ajustar adaptaciones frente a los cambios actuales y futuros, para esto se requiere comprender cambios históricos espacio-temporales en el patrón regional de lluvias. Para esto, se analizaron las tendencias de la precipitación mensual en escalas de la lluvia total-anual, mensualmultianual y semianual-trimestral; mediante la aplicación de la prueba no-paramétrica de Mann-Kendall en 108 estaciones pluviométricas, ubicadas en la cuenca alta-media del río Cauca. En los resultados, la precipitación anual tuvo tendencias significativas con rango de variación desde -9.3% (-147,3 mm) hasta +6.5% (+128,8 mm) por decenio con promedio de -0.7% (-7,7 mm), para 24 estaciones. A escala trimestral, en Junio-Julio-Agosto como periodo de menor pluviosidad al año, se encontró una disminución significativa de la precipitación, con promedio de -15% (-29 mm) por decenio, en el 19% (21) de las estaciones analizadas. Se concluye, que existe cambios en el régimen intranual de la precipitación y, tras comparar las tendencias en la precipitación anual con variables geográficas (altitud, latitud y longitud), por encima de los 1500 msnm y en latitud menor a 3 o 52'N en la cordillera de los Andes, existe reducción generalizada en la lluvia. Dichos cambios, afectarán negativamente la generación y la disponibilidad de la escorrentía, que representa la oferta hídrica en la cuenca. En futuras investigaciones, deben estudiarse los cambios en la precipitación a escala diaria y vincularse actores locales, para el ajuste de adaptaciones frente a los cambios.

Estudiar las alteraciones en la oferta hídrica asociadas a la variabilidad o al cambio climático, es importante para ajustar adaptaciones frente a los cambios actuales y futuros, para esto se requiere comprender cambios históricos espacio-temporales en el patrón regional de lluvias. Para esto, se analizaron las tendencias de la precipitación mensual en escalas de la lluvia total-anual, mensualmultianual y semianual-trimestral; mediante la aplicación de la prueba no-paramétrica de Mann-Kendall en 108 estaciones pluviométricas, ubicadas en la cuenca alta-media del río Cauca. En los resultados, la precipitación anual tuvo tendencias significativas con rango de variación desde -9.3% (-147,3 mm) hasta +6.5% (+128,8 mm) por decenio con promedio de -0.7% (-7,7 mm), para 24 estaciones. A escala trimestral, en Junio-Julio-Agosto como periodo de menor pluviosidad al año, se encontró una disminución significativa de la precipitación, con promedio de -15% (-29 mm) por decenio, en el 19% (21) de las estaciones analizadas. Se concluye, que existe cambios en el régimen intranual de la precipitación y, tras comparar las tendencias en la precipitación anual con variables geográficas (altitud, latitud y longitud), por encima de los 1500 msnm y en latitud menor a 3 o 52'N en la cordillera de los Andes, existe reducción generalizada en la lluvia. Dichos cambios, afectarán negativamente la generación y la disponibilidad de la escorrentía, que representa la oferta hídrica en la cuenca. En futuras investigaciones, deben estudiarse los cambios en la precipitación a escala diaria y vincularse actores locales, para el ajuste de adaptaciones frente a los cambios.

Estudiar las alteraciones en la oferta hídrica asociadas a la variabilidad o al cambio climático, es importante para ajustar adaptaciones frente a los cambios actuales y futuros, para esto se requiere comprender cambios históricos espacio-temporales en el patrón regional de lluvias. Para esto, se analizaron las tendencias de la precipitación mensual en escalas de la lluvia total-anual, mensualmultianual y semianual-trimestral; mediante la aplicación de la prueba no-paramétrica de Mann-Kendall en 108 estaciones pluviométricas, ubicadas en la cuenca alta-media del río Cauca. En los resultados, la precipitación anual tuvo tendencias significativas con rango de variación desde -9.3% (-147,3 mm) hasta +6.5% (+128,8 mm) por decenio con promedio de -0.7% (-7,7 mm), para 24 estaciones. A escala trimestral, en Junio-Julio-Agosto como periodo de menor pluviosidad al año, se encontró una disminución significativa de la precipitación, con promedio de -15% (-29 mm) por decenio, en el 19% (21) de las estaciones analizadas. Se concluye, que existe cambios en el régimen intranual de la precipitación y, tras comparar las tendencias en la precipitación anual con variables geográficas (altitud, latitud y longitud), por encima de los 1500 msnm y en latitud menor a 3 o 52'N en la cordillera de los Andes, existe reducción generalizada en la lluvia. Dichos cambios, afectarán negativamente la generación y la disponibilidad de la escorrentía, que representa la oferta hídrica en la cuenca. En futuras investigaciones, deben estudiarse los cambios en la precipitación a escala diaria y vincularse actores locales, para el ajuste de adaptaciones frente a los cambios.

El río Cauca es la principal fuente hídrica superficial del Valle del Cauca y en los últimos 25 años ha registrado importantes crecientes causando inundaciones como las ocurridas entre el periodo 2010 -2011, cuyos efectos repercutieron en pérdidas económicas para la región. Por tal motivo se realizó el análisis hidrológico de las crecientes históricas del río Cauca. La metodología se estructuró en tres etapas para identificar los factores hidrometeorológicos más influyentes: i) Descripción general de la cuenca para identificar las principales características; ii) Análisis de frecuencia de eventos máximos, aplicando funciones de distribución de probabilidad a las series de precipitaciones y caudales máximos diarios; y iii) Caracterización hidrológica de las crecientes posteriores a la construcción del embalse Salvajina (1988 -2011). Como resultado, se identificó que uno de los factores más influyente en las crecientes, son las precipitaciones asociadas a la fase fría del fenómeno El Niño Oscilación del Sur (ENOS), La Niña; las cuales afectan significativamente el caudal del río y sus tributarios.

Con el objetivo de detectar cambios o tendencias en la precipitación diaria registrada en las cuencas hidrográficas de los ríos Dagua y Cali, ubicadas al Sur-Occidente colombiano en el Valle del Cauca, se calcularon nueve índices de extremos climáticos utilizando el programa RClimDex. Para esto, se analizaron las tendencias de precipitación en 18 estaciones pluviométricas localizadas en la zona de estudio, con series históricas diarias que oscilaron entre los 21 y 56 años. Los datos fueron sometidos previamente a pruebas de homogeneidad para garantizar consistencia en la información. Los resultados indican cambios en la precipitación, dominados por tendencias crecientes para casi todos los índices; sin embargo la mayoría de las tendencias no presentan alta significancia estadística. Así mismo, se obtuvo un incremento significativo de la precipitación total anual promedio de 15,2 mm (cuenca río Dagua) y 9,1 mm (cuenca río Cali), en las estaciones ubicadas por debajo de los 1500 msnm;...

Estudiar las alteraciones en la oferta hídrica asociadas a la variabilidad o al cambio climático, es importante para ajustar adaptaciones frente a los cambios actuales y futuros, para esto se requiere comprender cambios históricos espacio-temporales en el patrón regional de lluvias. Para esto, se analizaron las tendencias de la precipitación mensual en escalas de la lluvia total-anual, mensualmultianual y semianual-trimestral; mediante la aplicación de la prueba no-paramétrica de Mann-Kendall en 108 estaciones pluviométricas, ubicadas en la cuenca alta-media del río Cauca. En los resultados, la precipitación anual tuvo tendencias significativas con rango de variación desde -9.3% (-147,3 mm) hasta +6.5% (+128,8 mm) por decenio con promedio de -0.7% (-7,7 mm), para 24 estaciones. A escala trimestral, en Junio-Julio-Agosto como periodo de menor pluviosidad al año, se encontró una disminución significativa de la precipitación, con promedio de -15% (-29 mm) por decenio, en el 19% (21) de las estaciones analizadas. Se concluye, que existe cambios en el régimen intranual de la precipitación y, tras comparar las tendencias en la precipitación anual con variables geográficas (altitud, latitud y longitud), por encima de los 1500 msnm y en latitud menor a 3 o 52'N en la cordillera de los Andes, existe reducción generalizada en la lluvia. Dichos cambios, afectarán negativamente la generación y la disponibilidad de la escorrentía, que representa la oferta hídrica en la cuenca. En futuras investigaciones, deben estudiarse los cambios en la precipitación a escala diaria y vincularse actores locales, para el ajuste de adaptaciones frente a los cambios.

Estudiar las alteraciones en la oferta hídrica asociadas a la variabilidad o al cambio climático, es importante para ajustar adaptaciones frente a los cambios actuales y futuros, para esto se requiere comprender cambios históricos espacio-temporales en el patrón regional de lluvias. Para esto, se analizaron las tendencias de la precipitación mensual en escalas de la lluvia total-anual, mensualmultianual y semianual-trimestral; mediante la aplicación de la prueba no-paramétrica de Mann-Kendall en 108 estaciones pluviométricas, ubicadas en la cuenca alta-media del río Cauca. En los resultados, la precipitación anual tuvo tendencias significativas con rango de variación desde -9.3% (-147,3 mm) hasta +6.5% (+128,8 mm) por decenio con promedio de -0.7% (-7,7 mm), para 24 estaciones. A escala trimestral, en Junio-Julio-Agosto como periodo de menor pluviosidad al año, se encontró una disminución significativa de la precipitación, con promedio de -15% (-29 mm) por decenio, en el 19% (21) de las estaciones analizadas. Se concluye, que existe cambios en el régimen intranual de la precipitación y, tras comparar las tendencias en la precipitación anual con variables geográficas (altitud, latitud y longitud), por encima de los 1500 msnm y en latitud menor a 3 o 52'N en la cordillera de los Andes, existe reducción generalizada en la lluvia. Dichos cambios, afectarán negativamente la generación y la disponibilidad de la escorrentía, que representa la oferta hídrica en la cuenca. En futuras investigaciones, deben estudiarse los cambios en la precipitación a escala diaria y vincularse actores locales, para el ajuste de adaptaciones frente a los cambios.

Unlike meteorological drought, hydrological drought in Indonesia has not been routinely monitored. This paper discusses hydrological drought monitoring and prediction system in Pemali-Comal River Basin by utilizing a Drought Early Warning System (DEWS) based on Delft-FEWS software. The Standardized Runoff Index (SRI) is applied to river discharges data which is collected through a real-time telemetering system. In case of unavailability of river discharge data, TRMM satellite rainfall data is used to simulate river discharges. A preliminary prototype of DEWS shows that the characteristics of previous drought events can be evaluated, and the simulation shows the possibility of forecasting hydrological drought with time lag of 6 months.

Partition behaviors of iron (Fe) and zinc (Zn) were studied in the alluvial sediments of River Gbako floodplains around Baddegi using empirical formulas. The samples were cored from three pits locations (TR-1, TR-2, and TR-3). Particle size distribution and geochemical analysis were performed. Particle size distribution results indicated that the sediments are sand dominated. They have more than 50% sand with smaller percentages of clay and silt. Average partition coefficient values of Fe in the sediments are 1.02, 0.83, and 0.88 for TR-1, TR-2, and TR-3, respectively, and for Zn are 1.02, 0.95, and 0.83, for TR-1, TR-2 and TR-3, respectively. The average velocities of Fe mobilization in the sediments are 0.08 m/day, 0.07 m/day and 0.09 m/day for TR-1, TR-2 and TR-3, respectively, and for Zn mobilization are 0.07 m/day, 0.07 m/day and 0.09 m/day, for TR-1, TR-2, and TR-3, respectively. The metals were preferentially partitioned in the sediments than the water percolating through the...

The river management is a critical and more focused area where it faces heavy water feeds due to rains and high-sloped catchment. Pahang River is an example of such situation and it receives runoff due to 220 mm average monthly rainfall. Malaysia is going on fast track of development in infrastructure and focusing on transformation process of economy. Keeping in view this fact, the vulnerability may cause due to floods in Pahang River and itseems to be a threat for the sustainable development of this area. The study has main objective of to find out possible technology tools to fine tune the existing hydro management system with a priority of healthy growth of country with minimized threats of flood disasters. Learning lessons from Australia, which is already under the process to develop computer aided river management, used as a guideline for the implication of this system for Pahang River in Malaysia. The study has investigated the broader aspects of river management handled by the system of computer aided river management (CARM). These aspects discussed in scenario of future demands for the development of such system for Pahang River. Suggestions and possible ways of action for the implications of computer aided river management identified with key role of all stakeholders. The prospectus of CARM and its adaptation is in the benefit of the country because of its sustainability and future focused development fashion.

During the implementation of the biological samplings in the CEMAS network (Control of the Status of Surface Water Bodies) in the Ebro River Basin, in application of the Water Framework Directive (period 2006-2010), the presence of the chlorophycean alga Tetrasporidium javanicum Möbius, 1893 was detected in the middle reaches of Ebro River, in lowland reaches of the main rivers of the left margin, and in some upper reaches, gullies and also in irrigation ditches. It is a species that is distributed mainly in tropical areas that until now had been scarcely reported in Spain and Europe. In this work, the distribution and ecological preferences of the species in the River Ebro Basin is shown.

Rational use of water resources is of current importance in the integrated use and regulation of flow. Therefore, a water management calculation is needed that will allow water resources to be distributed efficiently and unacceptably, without allowing them to be overused. The article discusses issues of assessing the water resources of the Aral-Syrdarya water basin. To analyze the hydrological characteristics of the basin under study, series of annual water runoff were reconstructed and chronological graphs of annual runoff were constructed. At calculating the parameters of the annual runoff, total and difference integral curves were constructed, the values of the annual runoff were determined using all sets of data from hydrological posts of the studied Syrdarya River basin. The main statistical parameters of the annual river runoff, random errors in the mathematical expectation and the coefficient of variation were assessed. For water management calculations, data from the report of the Aral-Syr Darya Basin Inspectorate on regulation of the use and protection of water resources for 2016, as well as the Scheme for the integrated use and protection of water resources in the river basin, were used. Syrdarya for 2018. Analysis of the water balance for the periods 2010-2018. takes into account that the incoming part of the water balance of the Aral-Syrdarya river basin was 81,690.69 million m3, the outgoing part was 82,446.35 million m 3 . Based on the data, a water balance was compiled and an analysis was made that the flow decreased by 755.66 million m 3 , which naturally affected the decrease in the level of the Aral Sea. Also, according to the water balance of the Shardara, Badamskoye, Bugunskoye and Kapshagai reservoirs, accumulation was positive. But in the Koshkurgan reservoir, accumulation was negative.

Nowadays, the condition of water pollution in Malaysia is becoming more serious because of the water quality is declining due to the anthropogenic activity that was carried out. Sungai Nyior has been chosen for this study of water quality which located in Balok Baru, Kuantan, Pahang with length and wide are 11.3 km and 20 m respectively. The objectives of this study were to evaluate the characteristics of current water quality in the study area based on National Water Quality Standard (NWQS) and Water Quality Index (WQI), Malaysia, to identify the possible factors or sources that influences the water quality of the river system and to make an appropriate suggestion for effective management of the water resources. To achieve the objectives, three times of water samples were collected monthly from September to November 2016. Physical, chemical and biological parameters were analyzed using standard methods. The WQI was calculated based on the concentration of pH, total suspended solid ...

Ocena količinskega stanja podzemnih voda je del Načrta upravljanja voda 2022-2027 (NUV III). Z njo po določenih kriterijih ovrednotimo količinsko stanje na 21 vodnih telesih podzemnih voda v Sloveniji kot »dobro« ali »slabo«. Ocena je izvedena s štirimi preizkusi, kjer analiziramo vpliv odvzemov (črpanih količin) podzemne vode na: količine podzemne vode in vodno bilanco, ekološko stanje površinskih vodnih teles, kopenske ekosisteme odvisne od podzemne vode in vdore slane vode ali vode slabše kakovosti v vodonosnik. Končno skupno oceno, na podlagi opravljenih preizkusov, določa kriterij najslabše ocene. Na podlagi rezultatov izvedenih preizkusov imamo 20 vodnih teles ocenjenih s skupno oceno »dobro«. Vodno telo Dravska kotlina pa je ocenjeno kot »slabo«, ker črpanje podzemne vode povzroča vdore vode slabše kakovosti v vodonosnik. Zadnja obdobna ocena količinskega stanja 1991-2020 razkriva, da imamo v plitvih vodonosnikih podzemnih vodnih teles letno na razpolago dobrih 4 milijarde m 3 podzemne vode. Odvzemi podzemne vode (črpane količine) so v obdobju 2014-2019 v plitvih vodonosnikih dosegali povprečno 135 milijonov m 3 /leto. Na območju globokega geotermalnega vodonosnika v Murski kotlini so odvzemi v tem obdobju ocenjeni na 2,5 milijona m 3 /leto. Numerični modeli simulirajo omejeno napajanje, ki se kaže kot izcejanje iz okoliških kamnin v geotermalni vodonosnik v višini približno 2,3 milijona m 3 termalne vode na leto.

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In Morocco, the silting in dams represents a tricky problem for the country. The total annual value of silting is estimated to 75 million m3. One of the strategic reservoirs, which displays these severe problems, is the dam of Mohamed Ben Abdelkrim Al Khattabi (MBAK). Sustained by the catchment area of Nekor and impounded in 1981, it constitutes the only source of water for the city of Al Hoceima and the surrounding urban centers (Imzouren, Béni Bouayach, etc.). In view of the advanced gullying, the water deficit of soils, the absence of vegetation cover and the brutality of flooding in the catchment area of Nekor, MBAK dam silts up at prejudicial pace for its lifespan. Thus, and since 1976, the government undertook several developments of multisector origin (department of hydraulics, forest service, agriculture, equipment) in order to ensure the conservation of the capital "water-soil" and to protect MBAK dam. The present study aims to reconstitute the historical data and...

This work addresses the impact of climate change on the hydrology of a catchment in the Mediterranean, a region that is highly susceptible to variations in rainfall and other components of the water budget. The assessment is based on a comparison of responses obtained from five hydrologic models implemented for the Rio Mannu catchment in southern Sardinia (Italy). The examined models -CATchment HYdrology (CATHY), Soil and Water Assessment Tool (SWAT), TOPographic Kinematic APproximation and Integration (TOPKAPI), TIN-based Real time Integrated Basin Simulator (tRIBS), and WAter balance SImulation Model (WASIM) -are all distributed hydrologic models but differ greatly in their representation of terrain features and physical processes and in their numerical complexity. After calibration and validation, the models were forced with biascorrected, downscaled outputs of four combinations of global and regional climate models in a reference and future (2041-2070) period under a single emission scenario. Climate forcing variations and the structure of the hydrologic models influence the different components of the catchment response. Three water availability response variablesdischarge, soil water content, and actual evapotranspiration -are analyzed. Simulation results from all five hydrologic models show for the future period decreasing mean annual streamflow and soil water content at 1 m depth. Actual evapotranspiration in the future will diminish according to four of the five models due to drier soil conditions. Despite their significant differences, the five hydrologic models responded similarly to the reduced precipitation and increased temperatures predicted by the climate models, and lend strong support to a future scenario of increased water shortages for this region of the Mediterranean basin. The multimodel framework adopted for this study allows estimation of the agreement between the five hydrologic models and between the four climate models. Pairwise comparison of the climate and hydrologic models is shown for the reference and future periods using a recently proposed metric that scales the Pearson correlation coefficient with a factor that accounts for systematic differences between datasets. The results from this analysis reflect the key structural differences between the hydrologic models, such as a representation of both vertical and lateral subsurface flow (CATHY, TOPKAPI, and tRIBS) and a detailed treatment of vegetation processes (SWAT and WASIM).

Changes in climate cause significant alterations in morphometric parameters and may lead to hydro-meteorological hazards. In this study, an attempt has been made to identify drainage morphometric characteristics through topographic, geologic and hydrological information to assess the extreme weather events (flood) over the Gandak River Basin (GRB). The standardized precipitation index (SPI) and rainfall anomaly index (RAI) were used for deducing extreme rainfall incidences derived from the Tropical Rainfall Measuring Mission precipitation datasets. An assembled frequency distribution as well as trends in RAI and SPI was calculated to understand the hydro-climatological behaviour of the basin. During the monsoon season, the years 1998, 2007, 2011, 2013 and 2017 witnessed the extreme flood events. The variations in heavy and intense rainfall in short time can be linked to extreme flood events, which leads to channel shifting and modifications, can be deduced from provided asymmetric factors and sinuosity index. The results illustrated that both the monsoonal rainfall and the frequency of extreme rainfall over the basin are increasing, which could be a reason for a high severity and frequency of flood events in the GRB. Flood • Standardized precipitation index (SPI) • Rainfall anomaly index (RAI) • Morphometric • Gandak basin (Indo-Nepal region) * R. K. Mall

Changes in climate cause significant alterations in morphometric parameters and may lead to hydro-meteorological hazards. In this study, an attempt has been made to identify drainage morphometric characteristics through topographic, geologic and hydrological information to assess the extreme weather events (flood) over the Gandak River Basin (GRB). The standardized precipitation index (SPI) and rainfall anomaly index (RAI) were used for deducing extreme rainfall incidences derived from the Tropical Rainfall Measuring Mission precipitation datasets. An assembled frequency distribution as well as trends in RAI and SPI was calculated to understand the hydro-climatological behaviour of the basin. During the monsoon season, the years 1998, 2007, 2011, 2013 and 2017 witnessed the extreme flood events. The variations in heavy and intense rainfall in short time can be linked to extreme flood events, which leads to channel shifting and modifications, can be deduced from provided asymmetric factors and sinuosity index. The results illustrated that both the monsoonal rainfall and the frequency of extreme rainfall over the basin are increasing, which could be a reason for a high severity and frequency of flood events in the GRB. Flood • Standardized precipitation index (SPI) • Rainfall anomaly index (RAI) • Morphometric • Gandak basin (Indo-Nepal region) * R. K. Mall

Assessing the removal of nitrogen (temporary and permanent) in large river basins is complex due to the dependency on climate, hydrological and physical characteristics, and ecosystems functioning. Measurements are generally limited in number and do not account for the full integration of all processes contributing to nitrogen retention in the river basin. However, the estimation of nitrogen retention by the ecosystems is crucial to understanding the nitrate water pollution and the N 2 O emissions to the atmosphere, as well as the lag time between the implementation of agrienvironmental measures to reduce nitrogen pollution and the improvement of water quality. Models have often been used to understand the dynamics of the river basin system. The objective of this study was to assess nitrogen retention in a large river basin, the Seine basin (∼65 000 km 2 , in France), through the application of three models with different levels of complexity developed for different specific purposes: the GREEN, SWAT and RiverStrahler models. The study analyses the different modelling approaches and compares their estimates of water nitrogen retention over an 11-year period. Then reflexions on the role played by nitrogen retention by aquatic ecosystems in integrated nutrient management are presented. The results of this study are relevant for the understanding of nitrogen retention processes at the large river basin scale and for the analysis of mitigation measure scenarios designed to reduce nitrogen impacts on aquatic ecosystems and climate.

Climate change affects the hydrological regime of the Palcmanská Maša water reservoir and the use of the water surface for recreational purposes. Within the contribution, climatological variables were analyzed, namely precipitation, temperatures and flows in the sub-basin above Stratená station in the Hnilec river basin. The results document the possibilities of recreational use of the given area.

The aim of the study is to analyse the monthly and annual variability of the flow of the Hornad River in the years 1973–2020. The research showed that an upward trend in annual air temperature, precipitation and flows was recorded throughout the catchment area. The analysis of the annual Richard-Baker Index (RBI) and flow variability (Cv) showed a clear downward trend in the variability indexes Cv and Richard-Baker Index in the analyzed multi-year period only at the Kysak station, which is located downstream of the dam. No such changes were observed at the remaining Margecany and Spisska Nova Ves stations, which are located above the dam. The analysis of average monthly Richard-Baker Index values over the course showed greater variation. Between 1973 and 2020, the Richard-Baker Index values ranged from 0 to 0.49 at the Spisska Nova Ves and Margecany hydrological stations, while at the Kysak station, the Richard-Baker Index ranged from 0 to 0.57, indicating large changes in short-ter...

This paper presents the study on the effect of surface water allocation that links between the hydrologic and economic from water used in power production for the Upper Ayeyarwaddy River Basin. Water and green growth requires that water allocation should be constrained by the amount of water that is available at a specific time. Aquarius (a modeling system for river basin development planning model) software is used in this paper. Aquarius is a state-of-the-art computer model devoted to the temporal and spatial allocation of water among competing uses in a river basin. The required data for this study are collected from the department of meteorological, the electric power and irrigation. In this study, monthly discharges are collected from five stations. Reservoir and hydropower plant are considered as case study. A flow network is created in the network worksheet screen (NWS) using Aquarius in this paper. Water system components (WSC) palette and tools palette that make up a flow network are a series of nodes and links are processes in Aquarius software. Nodes represent the demand sites and links represent the linkage between river reaches. Model results show that reservoir are released the natural flows, outflows, storages and evaporations and hydropowers are generated turbine flows, hydropower generation, hydrogenation benefit. The maximum hydropower generation of hydropower is Yeywa hydropower (32%) and the minimum hydropower generation is Zawgyi II hydropower (2%). The purpose of this study is the hydrologic and economic linkages of surface water allocation for hydropower in the Upper Ayeyarwaddy River Basin.

Climate variability poses a pressing shift to the hydrological cycle and diminishing water resource availability. This shift is a prevalent challenge to day-to-day activities in the Olifants River, South Africa. This study assessed rainfall, minimum and maximum temperature variability, trend analysis, and change point detection in the Olifants River using numerous statistical analysis methods, such as coefficient of variation, Kurtosis, skewness, Pettitt, Buishand, von Neumann, Standard normal homogeneity test (SNHT), Mann-Kendall, and Sen's slope tests for the period of 1988 to 2014. The result showed that annual rainfall in most stations had moderate variation, limited stations were negatively skewed, and not normally distributed. Most of the stations, such as X1E003, B5E004, and B1E003, show less variability (CV < 20), while the rest of the stations show moderate variation ranges (20 < CV < 30) for rainfall datasets. The results of kurtosis and skewness ranged from -0.41 to 1.10 and -0.12 to 0.46 for rainfall; -0.03 to 0.92 and -0.61 to -0.17 for maximum temperature; and 0.24 to 1.61 and -0.18 to 0.14 for minimum temperature, respectively. Furthermore, the majority of stations were negatively skewed for annual maximum and minimum temperatures. Unexpectedly, the homogeneity tests for annual rainfall and maximum temperature depict favorable results, while a few stations were found to be non-homogeneous for minimum temperature. Specifically, the trend analysis indicators such as Kendall's tau, S, p-value and Sen’s slope were results ranges from -0.03 to 0.15, -11 to 53, 0.28 to 1.0, and -1.95 to 4.98 for rainfall; 0.08 to 0.15, 29 to 51, 0.30 to 0.56, and 0.009 to 0.025 for maximum temperature; and 0.13 to 0.24, 45 to 85, 0.08 to 0.36, 0.01 to 0.014 for minimum temperature, respectively. The trend analysis result revealed that the highest percentage of stations were in increasing trend, while the magnitude varies slightly for annual rainfall, maximum, and minimum temperatures. Sustainable and innovative climate variability mitigation measures must be initiated to reduce the effects of variability in agricultural productivity and environmental changes. Future researchers can investigate the effects of natural and anthropogenic activities on water resources and their implications on water availability.

MIKE SHE hydrological model using three distinct scenarios was incorporated to analyze the influence of changing climatic conditions and alterations in land utilization patterns on river discharge dynamics integrating three climate data periods (1990 - 2000, 2001 - 2010, and 2011 - 2020) with three land use and land cover (LULC) maps (1990, 2005, and 2020). The model was systematically calibrated and validated, achieving Nash-Sutcliffe Efficiency (NSE) and coefficient of determination (R2) values of 0.83 and 0.82 for calibration and 0.80 and 0.81 for validation, respectively, demonstrating strong reliability in simulating the catchment’s hydrological processes. Results indicate substantial influence of both LULC and climate changes across 2001–2010 and 2011–2020. LULC alterations increased surface runoff by 10.29% and 2.38%, while subsurface flow and evapotranspiration decreased by -6.03% and -6.82%, and by 0.75% and -5.49%, respectively. Climate variations further augmented surface runoff by 2.14% and 12.72%, with corresponding reductions in subsurface flow and evapotranspiration of -7.43% and -10.40%, and -10.03% and -21.65%, respectively. Both climate and LULC changes promoted subsurface flow and evapotranspiration during 2001 - 2010, with declining trends observed during 2011 - 2020. The findings underscore that expanded settlements and reductions in forest and shrub land have intensified streamflow while lowering subsurface flow and evapotranspiration, emphasizing the need for integrated climate and land use considerations in water resource management strategies.

Hydrological processes are driven by complex interfaces between climatic variables and land surface characteristics. Variations in climatic conditions and land utilization patterns profoundly influence hydrological systems of drainage basins, reshaping storm water discharge mechanisms, soil absorption capacities, and subsurface water replenishment rates. These alterations disrupt the long-term viability of hydrological governance, influencing basin-scale water allocation, ecosystem health, and flood risk. Even though extensive research on the changes in hydrological regimes of shifting climatic patterns and human-driven landscape alterations have been undertaken but critical gaps still remain to understand the fundamental processes governing these interactions, particularly in data-scarce regions like Ethiopia. The need for high-resolution hydrological models effectively capture surface-subsurface water interactions in improving predictions and informing adaptive water management strategies.

Shifts in climate conditions driven by increasing greenhouse gas emissions has led to significant changes. Watershed hydrology is influenced by the uneven rainfall distribution, temperature regimes, and changes in water loss from soil and vegetation. These changes can alter streamflow patterns leading to increased duration and scale of extreme hydrological event including heavy rainfall and prolonged dry spells. The transformation of natural landscapes by deforestation, agricultural intensification, and urbanization augments disturbances in water cycles by disrupting runoff dynamics, limiting groundwater absorption, and reducing aquifer recharge rates. The convergence of shifting climate regimes and human-altered ecosystems often result in multiplicative impacts on basin stability, requiring adaptive modeling frameworks to project long-term hydrological shifts.

Hydrologic models though extensively applied, research gaps persist in accurately representing the synergistic impacts of climate and land use transformations on streamflow. Many existing studies rely on models such as SWAT and HEC-HMS, which is rarely applicable to large-scale watershed simulations, have limitations in integrating surface and subsurface water interactions at high spatial and temporal resolutions emphasized the need for distributed models capable of capturing finer hydrological complexities in changing landscapes. The MIKE SHE model, in contrast, offers a process-based, fully distributed approach that integrates surface water, groundwater, and evapotranspiration processes, making it particularly suitable for capturing fine-scale hydrological variations and interactions.

The Upper Omo Gibe catchment, a critical hydrological region in Ethiopia, has witnessed significant alterations in climate patterns and land utilization in past decades. Current research fully utilizes high-resolution models such as MIKE SHE to explore the synergistic impacts of these factors on streamflow. In Ethiopia, prior analyses using SWAT have emphasized broad hydrological trends driven by climate and land cover changes but overlooked localized mechanisms, such as subsurface flow dynamics that are vital for assessing fine-scale streamflow responses. Furthermore, existing research has predominantly examined either climate variability or land cover shifts as stand-alone factor, which is inadequate to capture their collective effects on hydrological processes. These linked processes is imperative for effective critical water resource planning and mitigating hydrological risks under climate change scenarios.

This analysis addresses the limitation by using the MIKE SHE model to evaluate the combined effects of climate variability and land cover changes on streamflow in the Upper Omo Gibe catchment. Thus, this research explores the watershed hydrology by integrating high resolution climate and land use data with process based hydrological modeling.

Daily climatological data including precipitation and temperature extremes (minimum and maximum) required for MIKE SHE model were obtained from the Ethiopian National Meteorological Agency (EMA). The data (1990 to 2020) were acquired from nine meteorological stations (1 - 9) and one hydrological station (10) to overcome problems of data continuity and delay in establishing the stations. The datasets were chosen for their completeness, long-term availability and appropriateness for model analysis. The streamflow data were collected from 1990 to 2014 from Ministry of Water and Energy (MoWE), Government of Ethiopia. The reference evapotranspiration values were computed using the Penman-Monteith method. The dataset was subjected to a thorough screening for outliers and incomplete data. Corrections were made by checking against records from neighboring stations. Catchments and monitoring stations were chosen for the completeness and quality of the available data and time series with less than 10% missing values for daily streamflow and monthly weather records. This rigorous selection and validation procedure ensured both extensive and accurate data integration

Several sections of this report contain detailed mathematical derivations and statistics. To facilitate reading and use of this report, the report is organized in a manner that presents the primary results first, then the detailed mathematical derivations and statistics in the sections that follow titled "Details of Analysis and Results". For those readers who are interested only in the primary results, rather than the derivations and details, they may wish to read the sections titled "Primary Results" and skip the sections titled "Details of Analysis and Results".

As the fertile topsoil is constantly washed away and agricultural production is decreased, soil erosion is a serious environmental issue that affects the entire planet. All river basins experience changes in land use that affect sediment dynamics, soil erodibility, and hydrologic response. The main reason for the faster erosion rates is frequently attributed to those alterations. In the current study, the Intensity of Erosion and Outflow (IntErO) model was used to estimate the sediment yield and maximum outflow from three river basins in Cluj County, Transylvania, Romania. Because the county is hilly and has significant erosion issues, it is essential to have a solid understanding of how soil erosion occurs in river basins. This will allow for more precise planning of soil conservation projects and will allow for more effective management of the severity of the erosion processes. The IntErO model offers quick, efficient, and feasible insight into how changing land use affects soil e...

The Nee Soon stream drainage in the Central Catchment Nature Reserve is virtually the last remaining fragment of primary freshwater swamp forest in Singapore. The forest type has been poorly studied in the Southeast Asia. The hydrology, water quality, as well as aquatic flora and fauna all have great theoretical and practical significance. The ecology and management of the Nee Soon freshwater swamp forest are reviewed, with remarks on their national, regional and global contexts. This review sets the scene for a three-year integrated conservation and management study completed in 2016.

This paper presents initial findings from research on the hydro-geomorphic status of Nee Soon freshwater swamp forest catchment in Singapore. The hydrological system of Nee Soon contains a swamp that is best described as an organic-rich wetland, with organic matter content as high as 40% near the surface (too low to be classified as peat). Total longterm denudation rate in the catchment is an estimated 23.4 ± 2.08 Mg km -2 yr -1 , with physical erosion (5.6 ± 0.5 Mg km -2 yr -1 ) and chemical weathering (17.8 ± 1.58 Mg km -2 yr -1 ) accounting for 24% and 76% of the totals, respectively. Age dating of a 1.95-m sediment core from the lower swamp indicates several distinct periods of variable sediment deposition (0.04 to 0.009 cm y -1 ) since 15,000 BCE, across a variety of climate regimes. A missing layer, representing more than a 7000 year period, verifies substantial channel erosion in the swamp occurring since 1950. Accelerated erosion associated with forest conversion to agriculture in the upper catchment could not be verified through examination of sediment cores. High concentrations of several heavy metals (e.g. As, Cr, Mn, Ni, Sr, V) in the lower catchment, compared with the upper catchment, appear to be natural (e.g. related to differences in the underlying bedrock), rather than contamination. The very high concentrations of lead, copper, and zinc associated with firing activities in the military range in the lower catchment are spatially isolated (e.g. shooting berms), and currently not posing a threat to the swamp environment. Other hydrogeomorphic degradation processes/activities now include disruption to hillslope soils and streams by trampling and mountain biking, back-flow of reservoir release water into the lower swamp area, and atmospheric deposition of contaminants.

Introduction

Accurate estimation of actual evapotranspiration (ETa) is essential for sustainable water resource management, particularly in arid and semi-arid regions. This study employed the SEBAL model in conjunction with Landsat 8 and 9 satellite imagery to estimate ETa in the Gareh Bygone Plain, Fars Province, during 2018–2021. The model integrated corrected satellite data and meteorological inputs to compute key surface energy balance components, including net radiation, soil heat flux, and latent heat flux. Calibration was enhanced by incorporating wind speed data, improving the model’s accuracy. ETa values varied seasonally, ranging from 0.8 to 3.2 mm/day in colder months and 1.8 to 6.5 mm/day during warmer periods. The model’s results were validated against FAO Penman-Monteith reference ET and field measurements, confirming strong agreement. Crop coefficient (Kc) estimates highlighted significant variability based on vegetation type and growth stages. The complementary use of the SEBS model yielded ETa estimations with a low error margin (3–5%), further confirming the reliability of remote sensing-based approaches. These findings support the application of calibrated satellite models and localized parameters in optimizing irrigation strategies and addressing water scarcity in semi-arid environments.

Accurate estimation of actual evapotranspiration (ETa) is crucial for water resource management and evaluating the efficiency of artificial recharge projects in arid regions. Traditional methods relying on point-based measurements often fail to represent large-scale and heterogeneous areas. Remote sensing technologies, utilizing satellite data and surface energy balance models such as SEBAL, enable precise estimation of ETa and crop coefficients (Kc) over extensive spatial and temporal scales. This study aimed to assess water consumption of various vegetation covers and the effectiveness of the flood spreading system in the Gareh Bygone plain, Fars Province, by developing improved models and analyzing the spatiotemporal distribution of ETa.



Materials and Methods

This study was carried out at the Kosar floodwater spreading station in the semi-arid Gareh Bygone Plain of southern Iran’s Fars Province.The Gareh Bygone Plain, with an approximate area of 192 square kilometers, is located downstream of three main watershed areas. The area features an semi-arid to arid climate, an average annual precipitation of 229 mm, and geology comprising limestone, marl, and conglomerates. Satellite data from Landsat 8 and 9, processed with geometric, radiometric, and atmospheric corrections, served as input for the SEBAL model. This model estimates actual evapotranspiration by integrating satellite imagery and meteorological data using the surface energy balance equation. Vegetation indices such as NDVI and SAVI, surface albedo, surface temperature, and other surface energy parameters were used in ETa estimation. Model results were validated with field measurements, including reference evapotranspiration, soil water balance, and estimates of return flow.



Results and Discussion

Satellite imagery from Landsat 8 Level 2, covering 2018–2021, was used to derive ETa maps via the SEBAL model. Due to data acquisition limitations in certain provinces, temporal coverage was incomplete. The SEBAL model, calibrated with meteorological data and incorporating wind speed as a parameter, showed good performance in estimating ETa, particularly in the Gareh Bygone plain. Comparison of SEBAL-derived ETa values with FAO Penman-Monteith reference estimates, using a crop coefficient (Kc=1.05), demonstrated the model’s reasonable accuracy. ETa values ranged from 0.8 to 3.2 mm/day during the cold season and from 1.8 to 6.5 mm/day in the warm season, reflecting a seasonal pattern consistent with the region’s climatic conditions. These results highlight the importance of using satellite data and optimizing model parameters for more accurate ETa estimation. Analysis of SEBAL model results revealed seasonal fluctuations in ETa influenced by temperature, solar radiation, and vegetation cover. ETa values ranged from 0.8 to 6.5 mm/day, peaking during the warm season. The crop coefficient (Kc) was closely linked to vegetation type and growth stage, emphasizing the need to consider these differences in water management. Field measurements of soil (moisture, texture, bulk density) in the Gareh Bygone plain indicated a progressive increase in water infiltration depth and return flow volume during the irrigation season. Comparison of SEBS model-derived ETa with field data confirmed the high accuracy of the SEBS model (error margin of 3–5%), demonstrating its superiority over traditional methods and its effectiveness for agricultural water resource management in semi-arid regions. Computational results showed an increasing trend in return flow volume throughout the 11 irrigation cycles, reaching a significant amount by the end of the season. This finding has important implications for water resource management in the region.



Conclusion

This study employed Landsat 8 imagery to estimate actual evapotranspiration (ETa) using the SEBAL model in the semi-arid Gareh Bygone Plain. Results indicate a strong correlation between seasonal ETa variations and temperature, solar radiation, and land surfaces vegetation activity, with peak ETa during the warm season (April-October) and minimum during the cold season (December-February). This seasonal pattern aligns with the semi-arid climate and highlights the importance of considering spatiotemporal variability in ETa estimations. Furthermore, incorporating wind speed significantly improved SEBAL model accuracy.

Introduction

Flooding, one of the most common natural disasters, poses a serious threat to ecosystems and human safety, with factors such as heavy rainfall, rapid snowmelt, dam failures, and poor management of water, soil, and vegetation resources exacerbating its impacts. Over the past two decades, approximately 2.4 billion people have been affected by natural disasters, resulting in economic damages amounting to $2.97 trillion. Among these, human-related factors such as reduced permeability, construction near riverbanks, and altering water flow paths have played a greater role in intensifying flood damage than natural factors. Accurate monitoring of floods and assessing affected areas are of significant importance. Flood zoning is a practical tool that plays a crucial role in managerial planning. Today, the combined use of optical and radar imagery can provide more comprehensive information. This study aims to effectively utilize Sentinel-1 and Sentinel-2 satellite images in conjunction with the Google Earth Engine (GEE) platform for flood mapping and vegetation indices in the Germi and Ungut counties, which have been impacted by flood events in May and June 2023. This innovative approach enhances the accuracy and speed of flood detection and offers a scalable solution for managing flood risks in vulnerable areas. By leveraging the latest advancements in remote sensing and cloud computing, this research contributes to developing more resilient strategies against flooding and is essential for regions like Ardabil Province, which are prone to irregular and heavy rainfall.



Materials and Methods

In this study, various methods were employed to identify and analyze flood-affected areas using Sentinel-1 and Sentinel-2 satellite data. Initially, Synthetic Aperture Radar (SAR) images from Sentinel-1 in the form of GRD (Ground Range Detected) products were utilized, which can capture images in all weather conditions and at any time of day. These data were derived from the C-band and Interferometric Wide Swath (IW) mode for flood mapping. To reduce speckle noise, the Refined Lee filter was applied, which removed random noise while preserving structural details. A threshold of 1.25 was set for VV polarization (vertical transmit, vertical receive) to identify flood-prone areas, with pixels having VV values above this threshold considered as flooded regions. To avoid misinterpretation, areas with permanent water bodies were excluded using JRC Global Surface Water data. SAR images of Sentinel-1 taken before, during, and after the flood (between April 1 and August 20, 2023) were compared for change detection. Additionally, Sentinel-2 images were used to calculate the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) to assess the impact of vegetation variability from April 1, 2019, to August 20, 2023. These methods effectively identified flood-affected areas and flood impacts on the vegetation cover of the two study counties.



Results and Discussion

In May and June 2023, the Germi and Ungut counties witnessed unprecedented rainfall, which led to severe flooding. The results of the interpretation of Sentinel-1 SAR images showed that about 185.83 km2 were affected by flooding, which is equivalent to 9.01 % of the total study area. Before the flood (April-May 2023), the mean NDVI and EVI respectively, were 0.25 and 0.18, indicating a significant decrease in vegetation cover compared to the reference year (April-May 2019). This could be due to land use change, drought, gradual destruction of dense vegetation, or other environmental stresses before the flood. At the time of the flood (June 2023), the mean NDVI and EVI reached 0.22 and 0.15, respectively, which are the lowest levels recorded up to that time. Only seven percent of the area had healthy vegetation during this period. This decrease could be due to the inundation of plants, destruction due to the intensity of the flood flow, or the covering of the soil surface by sediments. After the flood (August 2023), a more severe decrease in vegetation status was observed. The mean NDVI decreased to 0.15 and EVI to 0.1, and only about 2% of the area remained with healthy vegetation. This decrease may be due to severe soil degradation, erosion of the fertile topsoil, reduced vegetation cover due to seasonal conditions in the area.





Conclusion

This study mapped the June 2023 flood and vegetation indices in two counties of Germi and Ungut, located in the northwest of Iran, using Sentinel-1 SAR and Sentinel-2 data. In adverse weather conditions, SAR technology is an effective tool for mapping and monitoring flood-prone areas. The combination of SAR data, the Refined Lee filter, and the GEE platform facilitates crisis management and mitigates flood impacts. SAR's ability to penetrate cloud cover and provide rapid data access plays a critical role in the swift detection of floods. Integrating this technology with early warning systems enables quicker responses to floods, reducing both human casualties and financial losses. Analysis of the June 2023 Flood occurred in the two counties of Germi and Ungut, with an area of 2064 km2, showed that about 185.83 km2 (equivalent to nine percent of the total area) were directly affected by the flood. From an environmental perspective, the analysis of NDVI and EVI indices in four time periods (one reference period in 2019 and three time periods related to before, during, and after the flood of 2023) indicates a sharp decrease in the density and extent of vegetation cover in the region. The amount of desirable vegetation cover decreased from approximately 269 km² in the pre-flood period to only 41 km² in the post-flood period, indicating the destructive impact of the flood on the region's ecological structure. These findings emphasize the need for integrated watershed management and strategic land-use planning. To enhance community resilience, it is recommended to prioritize and protect vulnerable areas through strategic policies. Utilizing these results can help reduce flood damage and save time and costs in foundational studies.

Water resources management and planning requires accurate and reliable spring flood forecasts. In cold and snowy countries, particularly in snow-dominated watersheds, enhanced flood prediction requires adequate snowmelt estimation techniques. Whereas the majority of the studies on snow modeling have focused on comparing the performance of empirical techniques and physically based methods, very few studies have investigated empirical models and conceptual models for improving spring peak flow prediction. The objective of this study is to investigate the potential of empirical degree-day method (DDM) to effectively and accurately predict peak flows compared to sophisticated and conceptual SNOW-17 model at two watersheds in Canada: the La-Grande River Basin (LGRB) and the Upper Assiniboine river at Shellmouth Reservoir (UASR). Additional insightful contributions include the evaluation of a seasonal model calibration approach, an annual model calibration method, and two hydrological mod...

In East Africa, many drought events have occurred over the past few decades. Droughts have resulted in severe food crises, especially for countries relying heavily on agriculture. From the perspective of sustainability, utilizing groundwater for crop irrigation could be an avenue toward resilience to drought. In this study, we aim to use AI to identify optimal drilling locations for sustainable irrigation for subsistence agriculture. Our initial focus is the Hare watershed in southern Ethiopia. To identify suitable drilling locations, a hydrogeological model (TOPMODEL) for estimation of discharge and depth to water table will be implemented first; machine learning models will be constructed to estimate the probability of finding groundwater at a particular location; and finally these will be provided as inputs to an optimization model. Since this study is in progress, preliminary intermediate results are presented in this paper. A topographic wetness index (TWI) map was developed. T...

The objective of this paper was to evaluate the degree of anthropic transformation of a river basin in the Amazon region. We used the digital data of the TerraClass Project to calculate the Anthropic Transformation Index - ATI. In order to verify spatial and temporal changes along a decade in the Gurupi river basin, we used the database of the years 2004 and 2014. The results showed an increase of anthropic changes in the basin over a decade, as a result of forest cover conversion into agricultural and pastures areas. Although the Gurupi river basin remains at a regular level of degradation after a decade, the intensification of land use and land cover change is a threat to the few rainforest remnants of the river basin, which can lead the region to the next level of degradation, if effective forest protection, conservation and restoration actions are not implemented in the region.  

Introduction

For the sustainable development of the socio-economic economy, water resources are not only an important limiting factor but also play an irreplaceable "carrier" role. "Carrying capacity" is a term derived from ecology that refers to the limitation of the maximum number of individuals in specific environmental conditions. Water Resources Carrying Capacity (WRCC) is the support capacity of water resources for the livelihood of the region's population and socio-economic development. Due to the differences in water resource systems, socio-economic conditions, and ecological environmental settings in various regions and natural conditions, the assessment of WRCC does not follow a consistent pattern across different geographical areas, making the evaluation of WRCC a complex issue. The aim of assessing and analyzing WRCC is to determine the relationship between limited water resources and population, the environment, and economic development.

Wetlands play a pivotal role in sustainable development as a vital resource. With increasing population and economic growth, the pressure on water resources is rising. The Water Resource Carrying Capacity is defined as the ability of a water system to support human activities. In this study, considering the significance of Anzali wetland, which is being destroyed alongside the advancement of urbanization processes as one of the natural ecosystems, the water resources carrying capacity of Anzali wetland is being evaluated.

Materials and Methods

To evaluate the water resources carrying capacity, initially, the water resource system of the region was first modeled by using the system dynamics method and VENSIM software. Based on the modeling results, eight evaluation indicators were defined to assess the WRCC of Anzali Wetland, considering three subsystems: population, water resources, economy, and environment. Subsequently, based on the modeling results, indices were defined for each subsystem with the aim of assessing the water resources carrying capacity of Anzali wetland, with a total of 8 indices considered for evaluation. The weighting of the indices was done using the combined AHP-Entropy method .In order to accurately assess the carrying capacity of water resources, aligning the results with the actual situation of the region, and considering the water resources of Anzali Wetland, the current water resources and consumption in the Fumanat study area (located upstream of Anzali Wetland), the economic and environmental conditions of the region, and the use of water resources in the area, the evaluation indices were divided into four levels based on the standards for grading water resource carrying capacity indices in previous research. These levels are: I (loadable), II (weak), III (critical), and IV (extremely critical). Finally, using a fuzzy model and determining the membership degrees of the indices at each evaluation level and for each year, the water resources carrying capacity index of Anzali wetland was calculated for different evaluation levels over a 10-year period.

Results and Discussion

To determine the initial weights of the evaluation indices, expert opinions were utilized, and acceptable results were obtained using the Analytic Hierarchy Process (AHP) method and Consistency Ratio (CR). Subsequently, composite weights were calculated by combining the AHP weights with entropy, with the highest weight attributed to the indicator of water supply and demand ratio of the wetland (C7), followed by indicators such as the quality of input water resources and the impact of agricultural gross production. The results of this section demonstrate that the final composite weights are more realistic as the entropy method enhances the shortcomings of the AHP method, thereby improving the accuracy of the evaluation.

The results of the Water Resources Carrying Capacity (WRCC) assessment indicate a decreasing trend in the water resources carrying capacity of Anzali wetland between the years 1391 to 1400, shifting its capacity from level II (Weak) to level IV (Super Critical). The highest capacity is associated with the year 1391, while the lowest capacities are allocated to the years 1393, 1394, and 1400. Examination of the obstacle factors revealed that surface and groundwater resources significantly impact the water resources carrying capacity of the wetland, with several indicators from the water resources subsystem identified as the main obstacle factors in this regard. These constraints pose challenges to improving the wetland's capacity, and the increase or decrease of these resources, especially under environmental and economic conditions, significantly influences the wetland's status

Conclusion

The results showed that the WRCC of the wetland had a decreasing trend during the study period and had reached a supercritical state. The most important factors affecting the reduction in carrying capacity were identified as the shortage of surface and groundwater resources and the poor quality of water entering Anzali Wetland.The overall findings of the investigations indicate that Anzali wetland has been in critical and super-critical conditions in recent years, highlighting the necessity for planning to improve its situation. Considering the obstacle factors identified in this study, efforts can be directed towards planning and managing the wetland to move towards a more desirable state.

Introduction

Climate is one of the most important ecological factors, and its changes are currently the most important threat to sustainable development. The phenomenon of climate change causes different processes in the atmosphere and the earth. Phenomena such as rising sea levels, changes in meteorological variables such as temperature and precipitation, impact on surface currents, occurrence of floods and droughts, and changes in air currents and storms are only part of the effects of climate change. Therefore, it is necessary to model the future conditions of the climate to know the future conditions. There are various methods for simulating and predicting climate variables in future periods under the influence of climate change, the most reliable of which is the use of General Circulation Model (GCM) data. GCM models are only able to simulate the data of the atmospheric general circulation model at large levels. Even if global climate models are set up with high technical power to predict the future, the need to downscale the results of these models at station scales is felt. Therefore, in this research, the effects of climate change on the threshold values of precipitation and temperature have been evaluated using SSP scenarios.

Materials and Methods

General circulation models (GCMs) can provide the best information about the response of the atmosphere to increasing greenhouse gas concentrations. In this research, the climatic data of three synoptic stations of Abadeh, Shiraz and Lar, related to Fars province, were used. The data from three models ACCESS-ESM1-5, CNRM-CM6-1, and MRI-ESM2-0 are used from the general rotation models of the sixth report. Daily precipitation and maximum temperature data from 1990 to 2017 were used. Using the statistical model LARS-WG and three scenarios SSP126, SSP245 and SSP585, precipitation and maximum temperature have been downscaling. In this model, the process of generating artificial weather data is done in three parts: model calibration, model validation, and weather data generation. To evaluate the LARS-WG model, coefficient of determination (R2), root mean square error (RMSE) test statistics have been used. To investigate the relationship between precipitation and maximum temperature with different return periods, Gumbel distribution was used. The appropriate distribution for maximum precipitation, temperature, and flood data is Gumble's method; In this study, the distribution of precipitation and maximum temperature for different return periods is presented. In this method, the mean value and standard deviation of the data and the length of the data return period are considered to be the most important effective factors in estimating the maximum values.

Results and Discussion

Validation of the LARS-WG model was done by comparison between observation data and generated data. To evaluate the efficiency of the model, error test criteria have been used. The results show that the LARS-WG model was able to estimate the maximum temperature and precipitation. The accuracy of the modeling in the maximum temperature parameter has been more appropriate than the precipitation ratio. The monthly precipitation changes of the near future period (2021-2040) compared to the base period (1990-2017) of the three ACCESS-ESM1-5, CNRM-CM6-1 and MRI-ESM2-0 models of Abadeh synoptic station showed the amount of precipitation in April, May, June, August, and September has had a decreasing trend compared to the base period. The amount of precipitation in January, February, and December has also increased compared to the base period. At Abadeh station, it shows an increase in temperature under all three models and scenarios in the near future. At the Shiraz synoptic station, precipitation in April, July, and September has decreased compared to the base period. The amount of precipitation in January, February, and March has also increased compared to the base period. The maximum temperature has also increased. At the Lar synoptic station, the precipitation in April, September, and October has decreased compared to the base period. The amount of precipitation in January, February, and March has also increased compared to the base period. The maximum temperature has also increased. The Gumbel distribution output also showed that in all three stations, in a specific return period, precipitation and maximum temperature will increase compared to the base period. Examining the Gumbel distribution of precipitation values also shows an increase in precipitation in the specified return period in the ACCESS-ESM1-5 model.

Conclusion

The changes in the maximum temperature of the near future period (2021-2040) compared to the base period (1990-2017) were incremental in three stations and three models. In Abadeh synoptic station, the maximum temperature changes show an increase in the maximum temperature in the three scenarios SSP126, SSP245, and SSP585, respectively 1.57, 1.59, and 1.63 °C, and the amount of precipitation in the spring and summer seasons is decreasing and Winter precipitation is estimated to be increasing compared to the base period. In the Shiraz synoptic station, the maximum temperature shows an increase in the maximum temperature in the three scenarios SSP126, SSP245, and SSP585, 1.37, 1.50, and 1.48 °C, respectively, and in the ACCESS-ESM1-5 model, in all three scenarios, the amount It is estimated that the winter precipitation is decreasing and the amount of spring precipitation is increasing. The changes in the maximum temperature of Lar synoptic station show an increase in the maximum temperature in the three scenarios SSP126, SSP245, and SSP585, respectively 1.23, 1.37, and 1.28 °C. In the CNRM-CM6-1 model, the winter precipitation of this station is estimated to be a decreasing trend. Fall precipitation is also estimated in the MRI-ESM2-0 model in two scenarios, SSP126 and SSP585, but the ACCESS-ESM1-5 model has estimated an increase in the amount of precipitation in the Lar synoptic station in all seasons and scenarios. The Gumbel distribution output also showed that in all three stations, in a specific return period, precipitation and maximum temperature will increase compared to the base period. Therefore, extreme and heavy precipitation and the increase in the frequency of extreme events related to it, such as floods and droughts, are among the results of global warming.

Groundwater exploration in crystalline terrains depends on structural information among other factors like geology, rainfall, drainage, soil type, elevation and/or landuse classification. The spatial distribution of groundwater potential zones (GWPZs) in Asa and Oyun catchment areas, Kwara state, northcentral Nigeria was assessed using six thematic layers derived from satellite data and ancillary data. Landsat 8 OLI (2015), Digital Elevation Model (DEM), and aeromagnetic data were used to extract lineaments. Tropical Rainfall Measuring Mission (TRMM) data was used to generate spatially distributed rainfall using inverse distance weighted interpolation method. Slope and drainage were extracted from DEM. The natural colour composite of Landsat 8 was classified into 4 classes: Bareland, Vegetation, Waterbody, and settlement. The groundwater potential map of the study area was produced using a geographic information system (GIS) based Analytical Hierarchical Process (AHP) model of Linea...

The Aghien lagoon watershed is located in peripheral north-east areas of Abidjan. This space is accelerated population growth more than more important. The rate of urbanization is higher than 60% in 2014 (RGPH, 2014). Also, does the acceleration of urbanization result in vegetation cover degradation for the benefit of the built environment and a peri-urban agriculture. Also, does the acceleration of urbanization result in vegetation cover degradation for the benefit of the built environment and a peri-urban agriculture. This study aims to analyze in part one the diachronic evolution of vegetation cover between 1987-2000 and 2000-2015, and second part its takes stock of this dynamic between 1987 and 2015. Thus, the analysis of land use dynamics in the Aghien basin is based on the the vegetation mapping of landsat images. The methodology is based on the supervised classification by maximum likelihood of landsat images The results of the dynamics of land use in the basin in 1987, 2000 ...

Floods is one of the common unavoidable problems which have been causing problems and threatning to the people of Digaru and its adjoining areas from time to time. Flood hazards are one of the alarming phenomena in the region. During every rainy season the river overtops its bank and inundates the adjoining areas. Though Digaru and its catchment experiences flood almost every year, flood management policies are not adequate or mostly based on structural options including flood walls, dykes, embankments etc. Natural disasters have their greatest impact at local level especially on the lives of ordinary people. Current disasters are becoming more complex and the damages caused by the natural disaster at community level in Digaru catchment has increased exponentially in the past 20 years, despite the great efforts that the Government, NGO's and Local Communities have put into many disaster prevention programes. The objective of this paper is to assess flood hazard in Digaru and its catchment areas for the historical flood events using GIS approach and comprehend flood hazard management strategies for landuse planning. The database & methodology are Base mapping, topographic mapping and post-disaster verification of mapped floodplain extents and depths by DEM model using analogue maps through GIS approach. All possible combination of flood hazard maps are prepared using landcover, geomorphology and elevation heights for flood affected frequency and flood water depth of different flood seasons. The study related to natural hazards is a very new research in Arunachal Pradesh context that's too in the district of Lohit. The study area falls under a very strategic location i.e. Tidding thrust in the northern side and Mishmi thrust in the south-eastern side that makes the region geologically very fragile. This research work is a humble beginning where as researcher i will try to comprehend flood hazard management strategies for landuse planning decision proposed for the efficient management of future flood disasters.

Introduction

Evapotranspiration that includes evaporation from the soil surface and transpiration from vegetation, is one of the most important factors of water loss. Also, it is one of the most effective components of the water balance in a catchment in arid and semi-arid regions of the world. Therefore, it is an important physical parameter for water resource management and determining the plant water requirement in the agricultural sector. so far, many experimental methods have been proposed to calculate evapotranspiration, but, they are only suitable at the local scale and cannot be generalized to large areas due to regional dynamics and changes. whereas the accurate estimation of it is also very difficult and expensive, Therefore, in the present study, calculated the amount of evapotranspiration in the irrigated agricultural sector by using of landsat 8 satellite images and Surface Energy Balance Algorithm (SEBAL) in Nahavand Plain. in SEBAL algorithm by estimating all energy components on the earth's surface, including net radiation flux, soil heat flux, and sensible heat flux and using the energy balance equation, evapotranspiration is calculated. Remote sensing also has the ability to show evapotranspiration spatial distribution in addition to estimating the amount of its, because, it is the only technology that extracts factors such as surface temperature, albedo coefficient and plant index in a way compatible with the environment and is also economically affordable.

Materials and Methods

in this research, in order to estimate daily actual evapotranspiration of the irrigated agricultural and gardens of Nahavand Plain, extracted irrigated agricultural land use map by using of Sentinel 2 satellite images, Then, by using of Landsat 8 satellite images (13 images, from 13 April to 22 October during the growth period of the irrigated crops) and Surface Energy Balance Algorithm (SEBAL), evapotranspiration maps were obtained during the irrigated crops growth period in 2021. These Landsat 8satellite images are obtained by the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) onboard the satellites and are widely used for water resource applications. The OLI sensor has 9 bands and the TIRS has two bands (10th and 11th are the thermal bands). Landsat images are at intervals of 16-days with a spatial resolution of 30 m. In all images, the imaging time was 7:21. Then, due to FAO- Penman monteith method is one of the most important and reliable reference methods in evapotranspiration calculations, in this research, this method was used as a basis for evaluation and comparison. Finally, in order to evaluate the efficiency of SEBAL method in estimating the actual evapotranspiration of irrigated crops and gardens in Nahavand Plain used RMSE function (Root Mean Squares of Errors).

Results and Discussion

According to the results of the SEBAL algorithm, the highest mean of actual evapotranspiration was related to images 2021.09.04 and 2021.08.19 which fall in the middle of the growing period of irrigated crops. In addition, the surface albedo is noted to be relatively low for these days with the high NDVI values indicating high absorption of radiation by the vegetation during this period. Net solar radiation is directly contingent upon the incoming longwave and shortwave radiations, both of which directly influence the surface temperature. Therefore, areas with higher surface temperatures have higher net solar radiation. The net radiation flux has a direct relationship with NDVI, Greenness, and wetness parameters and is inversely related to albedo, Brightness, and Ts. The vegetative moisture and sensible heat flux are higher on days with high NDVI. Higher NDVI values are an indication of an increase in vegetation greenness, therefore essentially an increase in evapotranspiration is expected to be observed. The lowest mean of actual evapotranspiration is related to the northeast of the case study; due to lack of sufficient surface and ground water resources and consequently the reduction of agricultural lands in this region. Finally, in order to investigate the accuracy of SEBAL method in calculating evapotranspiration, compared the results of SEBAL method with the results of FAO- Penman monteith method. The results of this comparison showed that the SEBAL method with RMSE 0.82 has appropriate efficiency for estimating evapotranspiration.

Conclusion

Due to an increase in population and shortage of water resources, especially in the agricultural sector, researchers are looking for ways to better manage the available water resources. Evapotranspiration rate is one of the most important components of the global hydrologic cycle and has a significant influence on energy balance and climate. the using of indirect methods such as remote sensing can be an important step for estimating the water need of agricultural products, planning and management the country, s water resources. Therefore, according to the position of Nahavand city as the agricultural hub of Hamedan province, in this study, the actual evapotranspiration of the irrigated agricultural land use using of landsat 8 satellite images and SEBAL Algorithm was investigated in this area. According to the results of the SEBAL algorithm, the highest mean of actual evapotranspiration in all of the investigated images is related to the southeast and center of the studied area. that the reason of this matter is location of this area in the main branch of the Gamasiab River and focused the irrigated agricultural and gardens in this area. The final results of this research indicated high precision of SEBAL algorithm in estimating evapotranspiration. Thus, the high accuracy and low error indicate that the SEBAL method could be aptly used to estimate evapotranspiration on a regional scale, in the respective time range. Also, the results obtained from the SEBAL method assisted in understanding the spatial and temporal changes in different stages of plant growth.

Evapotranspiration, which includes evaporation from the soil surface and transpiration from vegetation, is one of the most important factors of water loss. Also, it is one of the most effective components of the water balance in a watershed in arid and semi-arid regions of the world. Therefore, it is an important physical parameter for water resource management and determining the water requirement of plants in the agricultural sector. So far, many experimental methods have been proposed to calculate evapotranspiration. However, they are only suitable at the local scale and cannot be generalized to large areas due to regional dynamics and variations. Moreover, the accurate estimation of evapotranspiration is also very difficult and expensive. Therefore, the present study calculated the amount of evapotranspiration in the irrigated agricultural sector using Landsat 8 satellite images and the Surface Energy Balance Algorithm (SEBAL) in Nahavand County. In the SEBAL algorithm by estimating all energy components on the Earth's surface, including net radiation flux, soil heat flux, and sensible heat flux and using the energy balance equation, evapotranspiration is calculated. Remote sensing can also show the spatial distribution of evapotranspiration in addition to estimating the amount of its, because, it is the only technology that extracts factors such as surface temperature, albedo, and vegetation indices in a way compatible with the environment and is also economically affordable. In this research, to estimate daily actual evapotranspiration of the irrigated agricultural lands and gardens of Nahavand County, an irrigated agricultural land-use map was extracted using Sentinel 2 satellite images. Then, using Landsat 8 satellite images (13 images, from April 13 to October 22 during the growth period of the irrigated crops) and Surface Energy Balance Algorithm (SEBAL), evapotranspiration maps were obtained during the irrigated crops growth period in 2021. These Landsat 8 satellite images were captured by the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) onboard the satellites and are widely used for water resource applications. The OLI sensor has 9 bands, and the TIRS has two bands (10th and 11th thermal bands). Landsat images are taken at 16-day intervals with a spatial resolution of 30 m. In all images, the imaging time was 7:21 AM. Then, since the FAO-Penman-Monteith method is one of the most important and reliable reference methods in evapotranspiration calculations, this method was used as a basis for evaluation and comparison. Finally, to evaluate the efficiency of the SEBAL method in estimating the actual evapotranspiration of irrigated crops and gardens in Nahavand County, the Root Mean Square Errors (RMSE) function was used. According to the results of the SEBAL algorithm, the highest mean of actual evapotranspiration occurred in the images from September 4, 2021 and August 19, 2021, which fall in the middle of the growing period of irrigated crops. In addition, the surface albedo was noted to be relatively low on these days, with high NDVI values indicating high radiation absorption by the vegetation during this period. Net solar radiation is directly influenced by the incoming longwave and shortwave radiation, both of which directly impact the surface temperature. Therefore, areas with higher surface temperatures receive higher net solar radiation. The net radiation flux has a direct relationship with NDVI, greenness, and wetness parameters and is inversely related to albedo, brightness, and surface temperature (Ts). Vegetative moisture and sensible heat flux are higher on days with high NDVI. Higher NDVI values indicate an increase in vegetation greenness; therefore, an increase in evapotranspiration is expected. The lowest mean actual evapotranspiration was observed in the northeastern part of the study area due to a lack of sufficient surface and groundwater resources and, consequently, a reduction in agricultural lands in this region. Finally, to investigate the accuracy of the SEBAL method in calculating evapotranspiration, the results of the SEBAL method were compared with those of the FAO-Penman-Monteith method. The results showed that the SEBAL method, with RMSE 0.82, has appropriate accuracy for estimating evapotranspiration. Due to population growth and water shortage, especially in the agricultural sector, researchers are looking for ways to optimize the management of available water resources. The evapotranspiration rate is one of the most important components of the global hydrological cycle and has a significant influence on the energy balance and climate. The use of indirect methods such as remote sensing can be an important step in estimating the water demand of agricultural crops, as well as planning and managing the country's water resources. Therefore, considering Nahavand County's position as the agricultural hub of Hamedan Province, this study investigated the actual evapotranspiration of the irrigated agricultural land using Landsat 8 satellite images and the SEBAL Algorithm. According to the SEBAL algorithm results, the highest mean actual evapotranspiration was observed in the southeastern and central parts of the study area. This can be attributed to the presence of the main branch of the Gamasiab River, which supports irrigated agricultural lands and gardens in this area. The final results of this research indicated the high precision of the SEBAL algorithm in estimating evapotranspiration. Thus, the high accuracy and low error rate indicate that the SEBAL method could be effectively used to estimate evapotranspiration on a regional scale over the given time period. Additionally, the results obtained from the SEBAL method assisted in understanding the spatial and temporal changes at different stages of plant growth.

Fresh surface waters from the Hawkesbury᎐Nepean River, the major river supplying water to the Sydney region in Ž south-eastern Australia, were sampled monthly during 1991 and analysed for major ions Na, K, Ca, Mg, Cl, SO and 4 . Ž . Ž . HCO , nutrients NO and PO , organic carbon and trace metals Al, Fe, Cu, Zn, Pb, Cd, Ni, Co and Mn . The 3 3 4 chemical composition of the river during 1991 was consistent with other studies of the river from 1977 to 1996. The Ž . major ion composition in the river is predominantly influenced by sea-salt aerosols in rainwater headwaters and Ž . connate sea-salt in groundwater mid-lower reaches , with a cationic dominance order of Na4 Mg) Ca ) K Ž . equivalents and an anionic order of Cl 4 HCO ) SO . This is typical of the headwaters of other permanent 3 4 Ž . coastal rivers freshwater in south-eastern Australia with a similar catchment lithology. These results differ markedly Ž from the most common natural major ion assemblages established for world rivers i.e. Ca ) Mg) Na ) K and . HCO ) SO ) Cl , which tend to be predominantly influenced by chemical weathering of rocks and minerals. The 3 4 mean concentrations of major ions, nutrients, organic carbon and trace metals in the freshwater reaches of the Hawkesbury᎐Nepean River increased by factors of 2.5᎐4.4, 14᎐18, 2.2 and 1.6᎐11, respectively, with increasing distance from the headwaters. Increases in major ion concentrations are attributed mainly to the increasing influence of saline groundwater inflows from regions of Wianamatta shale. Conversely, concentrations of nutrients, organic Ž . carbon and trace metals except Fe and Al increased as a consequence of anthropogenic inputs, particularly point Ž . discharges from sewage treatment plants i.e. showing distinct, but variable, concentration peaks , as well as diffuse urban andror agricultural runoff during storm events. The temporal variability of the mean concentrations of all measured parameters in this study was related to variability in water discharge. The mean concentrations of the major ions decreased by a factor of 1.5᎐3.0 with increasing water discharge, whereas the concentrations of nutrients, organic carbon and trace metals increased by a factor of 2.0᎐3.0, 1.6 and 1.3᎐2.0, respectively. This study provides the