Statistical Hydrology

Precipitation intensity-duration-frequency (IDF) Model was developed for designated regions in Southern Nigeria. Thirty-two years (1983Thirty-two years ( -2014) ) daily rainfall data were collected for Lagos, Ibadan, Benin, Calabar, Port Harcourt and Warri from Nigeria Meteorological Agency (NIMET) Oshodi, Lagos State for the study. The procedure of annual maximum series was used to select data sets for precipitation investigation. The advanced storm, a pattern developed by United State Department of Agriculture (USDA) Soil Conservation service was used to in the development of the models, which was used to break down daily rainfall into shorter durations. Gumbel and Log Pearson Type III distributions were used to compute the observed rainfall intensity values at durations of 10, 15, 20, 30, 60, 120, 180, 240, 300, and 360 minutes for return periods of 2, 5, 10, 25, 50, and 100 years. To obtain parameters for the IDF models for each location, the computed rainfall intensities were subjected to non-linear regression analysis using Microsoft Excel Optimization Technique Solver wizard for the respective durations and return periods. The performance of the models were analyzed by determining the chi-square(χ2 ), coefficient of determination (R 2 ), and root mean square error(RMSE) of the fitted distributions. Coefficient of determination values, R 2 obtained from the fitted IDF Models adopting Log Pearson Type 111 and Gumbel distributions gave perfect value of 1 for both regions. Gumbel distribution RMSE values ranged from 0.

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.

Nowadays there seems to be a consensus among the scientific community that, due to climate change, there is an intensification of the hydrological cycle, which, coupled with evidence of the impact of persistent modes of regional climate variability, have led hydrologists to study hydrological extremes under nonstationarity. In this paper, the peaks-over-threshold (POT) model with Poisson arrivals and generalized Pareto (GP) distributed exceedances is used to assess the influence of El-Niño Southern Oscillation (ENSO) in the flood regime of the Itajaí-Açu river, in Southern Brazil. The application of the POT approach has the advantage of being able to detect and model the influence of climate on the occurrence rate of floods and their peak magnitudes separately.

The compound labyrinth weir is a new type of labyrinth weir that is considered a good applicable choice for increasing the capacity of discharge. The flow over a compound labyrinth weir is a complex problem because the flow behavior is three-dimensional. The present study aims to simulate the flow over the compound labyrinth weir into the critical regions that cannot be observed when using an experimental test. The computational fluid dynamics (CFD) programme was utilised to implement a sensitive analysis for this purpose and under different flow conditions. The MAPE and RMSE indices were utilised to verify the CFD results with experimental work. The statistical indices of the maximum error ME, RMSE and MAPE were 4.7%, 0.033 and 3.9 respectively. Therefore, the findings showed that there is a good matching between the experimental and CFD results. The CFD results demonstrated that the hydraulics behaviour of the compound labyrinth weir was similar to the oblique and linear weirs in ...

The compound labyrinth weir is a new type of labyrinth weir that is considered a good applicable choice for increasing the capacity of discharge. The flow over a compound labyrinth weir is a complex problem because the flow behavior is three-dimensional. The present study aims to simulate the flow over the compound labyrinth weir into the critical regions that cannot be observed when using an experimental test. The computational fluid dynamics (CFD) programme was utilised to implement a sensitive analysis for this purpose and under different flow conditions. The MAPE and RMSE indices were utilised to verify the CFD results with experimental work. The statistical indices of the maximum error ME, RMSE and MAPE were 4.7%, 0.033 and 3.9 respectively. Therefore, the findings showed that there is a good matching between the experimental and CFD results. The CFD results demonstrated that the hydraulics behaviour of the compound labyrinth weir was similar to the oblique and linear weirs in ...

In hydrology, extreme value analysis is normally applied at stationary yearly maxima. However, climate variability can bias the estimation of extremes by partially invalidating the stationary assumption. Extreme value analysis for sub-yearly data may depart from stationarity (since maxima from one month may not be exchangeable with maxima from another) in terms of requiring to include it in the analysis. Here, we analyse the non-stationary structure of extreme monthly rainfall in Spain using two approaches: a parametric approach and an approach based on autoregressive time series models. Our analysis considers seasonality, climate variability and long-term trends for both approaches, and it compares both including their goodness of fit and complexity. The approach uses maximum likelihood estimation and Bayesian techniques. Our results show that autoregressive models outperform parametric models, providing a more accurate representation of extreme events when extrapolating outside of the period of fit.

Study region: Hadejia River Basin (HRB) in North Eastern Nigeria. Study focus: The hydrological trends and variations of surface runoff in Hadejia river catchment were assessed using data spanning 36 years for proper planning and management of water resources in the basin. New hydrological insight for the region: The temporal and spatial irregularities in the runoff of Hadeia river catchment has been detected. A significant decrease of river discharge from two out of the three downstream stations had been observed. However, there is an increasing trend of the river discharge from all the three upstream stations, though statistically insignificant. The ANOVA [F (5,210) = 106.226, P < 0.05] and cluster analysis results showed significant spatial variations between the upstream and downstream stations. The increasing trend of the discharge in the upstream stations is attributable to high rainfall mean and increased urbanization in the area. However, the significant decreasing trend of the discharge downstream of the river catchment is associated to many factors, notably; high evaporation rate due to high temperature, low rainfall mean and the relatively high infiltration rate encouraged by the high percentage of sandy soil and the sedimentary geological formation. Consequent to these trends and variations, water supply and irrigation, particularly in the downstream areas are at risk. Thus, integrated basin study using hydrological modelling will be helpful to distinguish the individual impact of the blame factors and to predict the river discharge behavior in response to the impact of those factors.

Study region: Hadejia River Basin (HRB) in North Eastern Nigeria. Study focus: The hydrological trends and variations of surface runoff in Hadejia river catchment were assessed using data spanning 36 years for proper planning and management of water resources in the basin. New hydrological insight for the region: The temporal and spatial irregularities in the runoff of Hadeia river catchment has been detected. A significant decrease of river discharge from two out of the three downstream stations had been observed. However, there is an increasing trend of the river discharge from all the three upstream stations, though statistically insignificant. The ANOVA [F (5,210) = 106.226, P < 0.05] and cluster analysis results showed significant spatial variations between the upstream and downstream stations. The increasing trend of the discharge in the upstream stations is attributable to high rainfall mean and increased urbanization in the area. However, the significant decreasing trend of the discharge downstream of the river catchment is associated to many factors, notably; high evaporation rate due to high temperature, low rainfall mean and the relatively high infiltration rate encouraged by the high percentage of sandy soil and the sedimentary geological formation. Consequent to these trends and variations, water supply and irrigation, particularly in the downstream areas are at risk. Thus, integrated basin study using hydrological modelling will be helpful to distinguish the individual impact of the blame factors and to predict the river discharge behavior in response to the impact of those factors.

Hydrological information is essential for adequate water resources management as well as for water supply, energy supply, water allocation, among other services. However, this information does not always exist in quantity and quality to be used in hydrological or water management studies, and alternative methods are required to estimate minimum flows. Estimation based on homogeneous regions enables to transfer observation data from a known location to a location without data, but in the same region. Since the fluviometric stations in the state of Goiás (Brazil) are not uniformly distributed, the present work aimed at delimiting homogeneous regions of minimum flows, using the cluster grouping method with the K-means algorithm.Thus, 71 fluviometric stations with at least 5 years of continuous data were selected, obtained from the HIDROWEB system. In addition to the observed data, other variables were considered, such as drainage area, perimeter, specific minimum flows Q7,10, Q90, Q95 and average slope. The use of all these variables together with the observed data made it possible to determine,with great accuracy, 5 homogeneous regions of minimum flows based on the cluster analysis, enabling to obtain the minimum flows of reference for each region.In the selected homogeneous regions, it was possible to observe that the regions with the highest values of average slope presented smaller minimum flows, and the same could be observed under inverse conditions, i.e., lower values of average slope had higher minimum flows.It is also noteworthy that river monitoring is deficient in the center-south and center-north parts of the state of Goiás, making water resources management difficult. This fact indicates, therefore, the need to expand the river monitoring system throughout the state, especially in its southern and northern regions.

This field study in Sitakunda, Bangladesh, conducted by Bangladesh University of Professionals, examined abiotic and biotic ecosystem components across five sites: Eco-park, Chandranath Hill, Khoiyachhora Waterfall, Mahamaya Lake, and Guliakhali Sea Beach. Key findings included geological features, soil properties, water resources, biodiversity, and human impacts on sustainability. Collaborative fieldwork highlighted ecological interdependencies and anthropogenic threats like unregulated tourism. The study underscores the need for community and policy interventions to mitigate environmental degradation and promote sustainable practices. Field observations emphasized the importance of hands-on learning in environmental science, bridging theory and practice for effective ecosystem management.

Keywords: Ecosystem dynamics, biodiversity, sustainability, anthropogenic impact, fieldwork.

Water is an indispensable resource for the survival of ecosystems and humanity but is sometimes subject to shortages and pollution. Today, the preservation of water resources is one of the fundamental challenges worldwide. The increase in withdrawals and discharges into nature, particularly into rivers, due to population growth and economic development, is increasingly threatening the quantity and quality of this resource, which is essential for human life. In a first step, water resources are used in various fields of active life such as agriculture, industry, generation, water supply, and fish production. On the other hand, water courses are also used as a source of wastewater, human waste. On a second step, intensive urbanization as well as climate changes caused, among others, by air pollution due to industrialization and various human actions. These latter factors have also contributed to the acceleration of extreme natural events supported by climate change, such as floods, which can lead to human and economic disasters. River management offers some solutions to address some environmental problems related to the water sector. Among these solutions are the construction of dams, texts of laws and standards for: discharges into the water environment; regulating water resources distribution. However, river development was designed for different sectors; in fact, it was a question of finding an effective solution to a given socio-economic problem. Thus, the aims were well defined, and the water system is managed as an element to be controlled without considering the degradation of the natural balances that can be generated, due to interactions between environment components. To consider interactions and interdependencies between these components, integrated water resources management (IWRM) is required. It includes the application of sustainable development principles to the water sector, and aims to integrate multiple stakeholders, competing uses and issues, including environmental preservation, to ensure the sustainability of water resources . Hydrological modeling is a tool that contributes to find solutions to several problems and applications related to integrated water resources management. In fact, it allows the simulation of the various interactions which govern the environmental study system by working with simplified physical and mathematical models. An integrated approach considers the different dimensions of the resource (quality, quantity, uses, environments, etc.) and the interactions between these dimensions. However, a water resource and its uses constitute a complex system: a set of many variables linked by interactions. The behavior of this system is not easy to understand: the use of modeling can improve its understanding and support decision making. Many researchers developed various hydrologic models to manage water resources and estimate rainfall-runoffs amounts, for examples: Tank model , the HBV model ), GR4 (Perrin et al., 2007). Thus, hydrological modeling can be considered as an essential decision-support tool for political decision-makers, researchers, and engineers to help them manage various situations and also to carry out preventive work in various fields such as flood forecasting, water quality, agricultural water sustainable.

Weirs are among the most essential hydraulic structures for measuring water discharge in open channels. The prediction of water discharge
over weirs should be as precise and straightforward measured as feasible. The experimental investigation of flow prediction over varied
heights of a conventional rectangular sharp-crested weir was conducted in the present work. The investigation evaluated five ratios of
weir height to length, P/b, of 0.33, 0.4, 0.47, 0.53, and 0.6, different water discharges, Q, of up to 17.25 L/s, and different bed slopes, S,
between 0.001 and 0.01. The experiment’s findings reveal that a change in the bed slope has no significant effect on the brink depth, hb,
for a constant water discharge. However, it influences the head over the weir, h, which is usually measured upstream of the weir location
and used to predict water discharge. A simple, accurate formula was developed for predicting water discharge over rectangular sharpcrested weirs depending on the brink depth with mean absolute percent error (MAPE) and root-mean-square error (RMSE) of 1.714% and
0.229, respectively. In addition to having a simple form, the developed formula performs well, is unaffected by the bed slope, and applies
to a wide range of h/P values, from 0.158 to 0.945.

Kebudayaan adalah rangkaian kegiatan yang dilakukan oleh manusia sebagai bentuk hak cipta, rasa, dan karsa yang berguna untuk mencapai pemenuhan kehidupan manusia. Menurut Taum (Nurjamilah, 2015) keragaman adat istiadat dan budaya Indonesia menjadikan Indonesia kekayaan nilai budaya dan sastra sebagai sastra lama. Nilai-nilai budaya dan sastra ini diciptakan dan diwariskan secara turun-temurun oleh nenek moyang kepada masyarakat hingga zaman modern.
Di Indonesia terdapat pawang hujan yang merupakan aktivitas ritual yang berkaitan dengan pemanggilan, penolakan, pemindahan, atau pengalihan hujan. Kegiatan ini merupakan tradisi turun menurun dan menjadi bagian budaya Indonesia. Ritual menolak atau memanggil hujan dilakukan oleh pawang tidak hanya dikenal di Indonesia, namun juga terjadi berbagai tradisi dan budaya di dunia. Ritual menolak hujan pernah terjadi pada pembukaan Olimpiade Beijing tahun 2008, sementara di India terdapat ritual memanggil hujan dilakukan petani dengan cara membuka baju dan memperlihatkan dada. Kegiatan memindahkan, mengalihkan, menolak, ataumemanggil hujan di berbagai daerah di Indonesia memiliki cara dan tradisi yang unik.

This research developed IDF curves and derived empirical equations for the Weta Area to estimate design rainfall. Daily rainfall data of Rain Gauge and Tropical Rainfall Measuring Mission (TRMM) 3B42 over 22 years for Weta were obtained from the Ghana Meteorological Services and National Aeronautics and Space Administration, respectively. The Indian Meteorological Department formula was used to disaggregate the daily data into hourly synthetic series to develop the IDF curves. The combined dataset was subjected to frequency analysis to determine the distribution which best characterize the dataset. The results demonstrated that the IDF curves provided higher intensities for shorter durations (0.08-h, 0.17-h, 0.25 h, and 0.5 h) while lower intensities for longer durations (1 h, 2-h, 6-h, 12 h and 24 h). The rainfall intensities and return periods are parallel and high intensities correlated with brief durations for the same return period. TRMM overestimated rainfall compared to Rain Gauge data. The IDF curves and derived empirical equations are useful scientific tools for hydraulic infrastructure design and water resources planning and management.

Rainfall frequency analyses for four cities namely Benin City, Port Harcourt, Calabar and Uyo in Nigeria's Niger Delta area were carried out utilizing daily rainfall data from the yearly maxima series for 48 years (1965-2012) at each location. The study's goal was to identify the probability distribution model that fit the data the best and applicable to each location from among six candidate probability distribution models namely: Pearson Type III (PIII), log Normal (LN), log Pearson Type III, Generalized Extreme value (GEV), Extreme value type I (EVI), and Generalized Pareto (GPA). The method of moments (MOM) was used to estimate the distributions' parameters applying the outcomes of seven goodness of fit tests, the most optimal fit distribution model was chosen for each site namely Root Mean Squared Error (RMSE), Relative Root Mean Square Error (RRMSE), Maximum Absolute Derivation Index (MADI), Chi-Square etc. The best distribution model at each location was utilized to predict rainfall of desired return periods. Based on our findings, PIII for Benin City, GEV for Port Harcourt, GEV for Calabar and EVI and LN for Uyo are the distribution models that suit the data the best., The Best Fit Probability Distribution Model predicted rainfall return values (RT) at 200 years return period ranging from192.92mm at Uyo, 185mm at Port Harcourt; 218mm for Benin City; and 245 mm at Calabar.. The study's findings are helpful in the planning, designing, and maintaining of hydraulic structures for preventing flood damage and mitigating floods at the locations

In the design of hydraulic engineering works, the estimation of project precipitation is fundamental. Rain forecasting depends on several factors, which makes estimating it simpler with stochastic processes. In this sense, the distributions of Gumbel (GUM), Log-Normal two-parameter (LN2P), Generalized Extreme Value (GEV), Frechet with two and three parameters (FRE2P and FRE3P), Weibull with two and three parameters (W2P and W3P), Gamma (GAM2P), and Pareto with two and three parameters (PAR2P and PAR3P) were evaluated to the annual maximum daily precipitation (AMDP) adjustment in the city of Caruaru (Pernambuco´s Agreste). A series of AMDP was used, based on data obtained from the National Water Agency (Agencia Nacional de Aguas - ANA). Anderson Darling (AD), Kolmogorov-Smirnov (KS) and Pearson Chi-square (χ2) adherence tests, and the determination coefficient (R²) were used to assess the adherence quality of the distributions. The Likelihood Method presented a better fit quality tha...

Weirs are the common and important structures which are used in controlling and measuring the flow in irrigation channel. This study carried out experimental runs to survey the velocity distributions in each vertical and longitudinal directions, downstream compound weirs. It uses compound sharp-crested weirs consisting of two triangular parts with different weir angles. All parameters, such as head over the weir, h, downstream water depth, ytail, bed type, and the shape of the compound weir, which affect the velocity distribution were studied. Three weirs, 90/90, 90/120, and 90/150, two beds, sand and plastic, four heads, 6, 9, 12, and 15 cm, and three downstream depths, 10, 14, and 18 cm were used. The results show that the vertical and longitudinal velocity distributions increase with water head and with plastic bed case. The velocity distributions decrease for larger wide weir and higher downstream water depth.

Groundwater forms the major source of drinking water in the rural areas of most of the developing nations of the world. This study was carried out to assess the major ion concentrations in groundwater of Kalwakurthy area, Mahabubnagar District, where groundwater is the main source of drinking water. Fifty six representative groundwater samples were collected from bore wells and dug wells were analyzed and analyzed for pH, EC, Ca+2, Mg+2, Na+, K+, CO3-, HCO3-, Cl-, TH, TDS, SO4-, NO3and F. As per the desirable and maximum permissible limit for Fluoride (1.5 mg/l) and Nitrate (45 mg/l) in drinking water and prescribed by WHO (2004) and Bureau of Indian Standards (2009), 46% groundwater sources in the study area is unfit for drinking purposes. Due to the higher fluoride levels in drinking water several cases of dental and skeletal fluorosis have appeared at alarming rate in the investigated area. The study revealed that 43% of the samples were found to be unsuitable for drinking purpos...

A study was conducted on the productivity and quality analysis of borehole water in Offa and Erin-Ile in Kwara State, and in Ilesa and Osogbo in Osun State, Nigeria. Productivity of the borehole was carried out by pumping test to determine the discharge from the boreholes sampled. Data about the boreholes were obtained from Hydrology Department of the Lower Niger River Basin Development Authority Ilorin, Kwara State (LNRBDA) and Rural Water and Environmental Sanitation Agency in Osun State (RUWESA). Ten boreholes were sampled in Offa out of which seven were working. Five boreholes in Erin-Ile were sampled out of which four were functional. 21 boreholes were sampled in Ilesa but only thirteen were working and three boreholes in Osogbo but only one was working. All the boreholes sampled were free from E-Coli bacteria. Most chemicals analyzed were within the permissible limits of the Standard Organisation of Nigeria (SON) Act 2007 but magnesium contents were above the permissible limits (0.20) by a range of 0.09 mg/L, iron (II) above the limits (0.30) by a range of 0.50 mg/L. Water from the boreholes of both states was suitable for human consumption.

A study was conducted on the productivity and quality analysis of borehole water in Offa and Erin-Ile in Kwara State, and in Ilesa and Osogbo in Osun State, Nigeria. Productivity of the borehole was carried out by pumping test to determine the discharge from the boreholes sampled. Data about the boreholes were obtained from Hydrology Department of the Lower Niger River Basin Development Authority Ilorin, Kwara State (LNRBDA) and Rural Water and Environmental Sanitation Agency in Osun State (RUWESA). Ten boreholes were sampled in Offa out of which seven were working. Five boreholes in Erin-Ile were sampled out of which four were functional. 21 boreholes were sampled in Ilesa but only thirteen were working and three boreholes in Osogbo but only one was working. All the boreholes sampled were free from E-Coli bacteria. Most chemicals analyzed were within the permissible limits of the Standard Organisation of Nigeria (SON) Act 2007 but magnesium contents were above the permissible limits (0.20) by a range of 0.09 mg/L, iron (II) above the limits (0.30) by a range of 0.50 mg/L. Water from the boreholes of both states was suitable for human consumption.

This paper addresses the problem of how drought definition by POT and SPA methods influences drought characteristics. Using the 19842013 daily flows at 24 selected gauging stations in the Dunajec river basin and assuming two threshold levels Q70% and Q95% and four minimum drought durations (5, 7, 10 and 14 days) as the pre-set criteria, it was shown that, when compared to the POT method, the application of the SPA method usually leads to less number of droughts and, consequently, of longer duration. The SPA method, differently from POT, reduces dramatically the number of inter-event times, which suggests that some adjacent POT droughts may be dependent and should be pooled.

This paper deals with flood estimation in ungauged catchment using continuous rainfall-runoff model. The rainfall-runoff model used in this study is developed based on the ENKI hydrological framework. In this study, flood estimation in ungauged catchment is based on transfer of parameter values from nearby station. The catchment used in this study to test the suitability of the ENKI system in flood estimation of ungauged catchment is the Gaula catchment located in Norway. This catchment has three main sub-catchments where flow records are available. The ENKI system is calibrated for each sub-catchment. In order to test its suitability in flood estimation, the average of the parameter set obtained from any of the two sub-catchments is used in the remaining sub-catchments. The performance of the ENKI system in flood estimation is evaluated in terms of the Nash-Sutcliffe (NSE) model efficiency index and the model ability to simulate the daily observed Annual Maximum Series (AMS). The result of this study shows that the ENKI framework has considerable potential in flood estimation in ungauged catchments.

IntisariTelah didesain sebuah usulan pemanfaatan teknologi modifikasi cuaca (TMC) dengan ground-based generator (GBG) untuk menambah debit aliran sungai Mamasa di Sulawesi guna meningkatkan produksi listrik dari Pembangkit Listrik Tenaga Air (PLTA) Bakaru. GBG adalah metode alternatif operasi penyemaian awan dari darat menggunakan menara. Penelitian tentang GBG telah selesai dilakukan di kawasan Puncak Bogor yang merupakan bagian dari sistem orografik Gunung Gede-Pangrango. Daerah Aliran Sungai (DAS) Mamasa memiliki kemiringan lereng antara 25%-40%. Topografi dengan kelerengan curam berada di bagian tengah, sebagian kecil di bagian hulu serta di bagian hilir DAS. Faktor orografi sangat dominan dalam pembentukan awan di DAS Mamasa. Uap air yang masuk ke DAS dipaksa naik oleh pebukitan di batas DAS sehingga terjadi pembentukan awan. Bagian tengah DAS sisi sebelah barat (Sikuku dan Sumarorong) memiliki curah hujan paling banyak sedangkan bagian tengah sisi sebelah timur (Rippung, Tabon...

The change in climate elements such as rainfall and temperature are determinant factors of hydrological components (e.g., streamflow, water yield, evapotranspiration). Thus, understanding the trends of hydro-climate variables are imperative for planning water resources management measures. This study examines the trends of precipitation and temperature (1980-2014) as well as streamflow (1990-2008) changes in the Jemma sub-basin of the Upper Blue Nile (Abbay) Basin. A homogeneity test was performed for pre-processing data to inspect the statistical nature of data homogeneity viz., Pettitt's, SNHT, Buishand range test, and Von Neumann test (VNT). The Mann-Kendall (MK) test, Modified Mann-Kendall (MMK) test, Sen's slope estimator, and Innovative trend analysis (ITA) were applied to compute the existence of trend and the magnitude of change at an annual timescale. In a nutshell, the study portrays a change in the trends of hydro-climate variables when using different statistical tests. The result showed that the mean annual temperature in many stations depicted upward trends. There is a significant increasing trend (p < 0.05) by 0.029 °C per year in the mean annual temperature of all climatic stations. Based on Sen's slope estimator, the annual precipitation and streamflow were increased by 1.781 mm/year and 0.085 m 3 /s, respectively. But no significant trends were detected in precipitation and streamflow when using Sen's slope estimator test. The results of this study are worthwhile for evaluating the trends of hydro-climatic variables in other areas of Ethiopia in particular and elsewhere in the world in general, which are fundamental for planning water resource management measures.

Object of the study is surface water bodies from category "rivers" according to Water Framework Directive 2000/60/ЕС. Surface water assessment is important for number of activities such as: water management in the country, making reports to international agencies, determining the change of the resources in the light of upcoming climate changes. The determination of water resources is based on information of hydrometric stations from the monitoring network system in the National Institute of Meteorology and Hydrology-Bulgarian Academy of Sciences (NIMH-BAS) in which real ongoing and available water flows that are subject of management are registered. In the study a technology for surface water bodies in the Bulgarian basins of the lower Danube is applied which has been developed in the frame of cooperative project together with the Ministry of Environment and Water. This is absolutely true for the Bulgarian section of the Danube River basin which is expressed in big number and variety of hydrological homogeneous sections. The river flow is characterized with annual and inter-annual variability determined by climatic factors and anthropogenic influences. The main obtained results of the present hydrologic studies are the usage of transferred information from gauged to ungauged watersheds and the estimation of the surface water bodies' resources using original regression relationships based on multiannual hydrological information from the NIMH-BAS monitoring network. The relationships delineate the hydrological homogeneous areas with similar conditions of flow formation. The estimated resources have significant usefulness for all State institutions managing the water in the Danube basin and have already been introduced in the operative and management practice.

This study aimed to develop a methodology based on multivariate statistical analysis of principal components and cluster analysis, in order to identify the most representative variables in studies of minimum streamflow regionalization, and to optimize the identification of the hydrologically homogeneous regions for the Doce river basin. Ten variables were used, referring to the river basin climatic and morphometric characteristics. These variables were individualized for each of the 61 gauging stations. Three dependent variables that are indicative of minimum streamflow (Q7,10, Q90 and Q95). And seven independent variables that concern to climatic and morphometric characteristics of the basin (total annual rainfall – Pa; total semiannual rainfall of the dry and of the rainy season – Pss and Psc; watershed drainage area – Ad; length of the main river – Lp; total length of the rivers – Lt; and average watershed slope – SL). The results of the principal component analysis pointed out t...

In topological dynamical systems (TDS), recurrence (periodic-like recurrence) is one of the important concepts in its studies but one major problem is the inability to demonstrate and/or illustrate its formation in the orbit structure of system from a topological point of view. In this paper, the logistic function was applied to demonstrate the periodic point as a recurrent formation (periodic-like recurrence) in the topological dynamical system and dynamical system. The Wolfram Alpha computational knowledge engine was used in obtaining the tables and the figures for the study through various examples of the logistic function. The study shows that period-2 recurrence is formed when the trajectory of the function is made up of two different values that keep repeating after successive iterations as a result of the period-2 orbits when the parameter of the function is between 3 and 3.45. The study again shows that when the parameter of the function is greater than 3.83 there is a period-3 point hence the formation of other periodic points. Convincingly, beyond this period-3 is another subsequent period called the period-doubling cascade leading into chaos. This period-doubling asserts that other periodiclike recurrences are also present, hence periodrecurrent exists.

Extreme hydrological events have gained notoriety in recent decades, thus recommended elements of decision-making assistance are important. In this context, this study focused on analyzing the temporal behavior of the maximum rainfall and waterflow recorded in the city of Rio Branco, Acre (Brazil), in addition to analyzing their frequencies, highlighting the reference quantiles and their reported probabilities of recurrence. The results pointed to a linearly upward trend, both for flow and rainfall, but these differences were not statistically significant according to the Mann-Kendall and Spearman Rho tests (α = 5%), leading to the conclusion for the occurrence of changes in hydrological patterns in Rio Branco, although statistically non-significant. However, it is warned to the precocity of attributing the main cause of such changes to either anthropic or natural actions. Regarding frequency analysis, it was found that Gumbel distribution is proper to the adjustment of the studied ...

The present study has the objective of investigating the hypothesis of stationary behavior in the streamflow regime of the upper Juruá river basin. For this purpose, the annual maximum daily flow data recorded at stations located in Cruzeiro do Sul and Marechal Thaumaturgo, AC, Brazil, were analyzed using the Mann-Kendall, Pettitt, and Spearman’s Rho tests. The results show sufficient evidence to conclude that, in Cruzeiro do Sul, the flow rates present an ascending temporal behavior, while in Marechal Thaumaturgo it is descending. However, this tendency is not significant (p&lt;0.05), allowing to conclude in favor of the stationarity hypothesis in the streamflow series of the referred basin. Thus, one of the physical implications associated to the results obtained may be the conclusion that the streamflow regime in the Upper Juruá basin has not changed significantly over time.

The verification of temporal trends in historical series and the frequency analysis of maximum precipitations events are important for the understanding of the dynamics of the hydro-meteorological processes. In this context, this study aimed at verifying series trends in the observed data from the annual maximum monthly precipitations in Cruzeiro do Sul, Acre State, Brazil, registered at 82704 station (7°38'S; 72°40'W) operated by the National Meteorological Institute, besides performing the frequency analysis through Gumbel probabilistic distribution for the maximum events. The results obtained through Mann-Kendall test suggest a light increasing temporal trend; however, it converges on rejecting the hypothesis of a significant trend, at the significance level of 5%, considering the analysis between 1971 and 2013. Regarding the frequency analysis, it was shown that Gumbel's distribution was appropriate to represent the maximum precipitation, through the adherence obtained by the Kolmogorov-Smirnov and the Chi-Square tests, to 5% probability.

The Brazilian Cerrado biome (BCB) is among 25 biodiversity hotspots identified worldwide, and covers the recharge area of important aquifers and rivers in South America. The increase in deforestation has been threatening water availability in this region. In order to assist in the water-resource management of the BCB, this study models the daily streamflow in a basin of the Cerrado, using two approaches: a process-based model (Soil and Water Assessment Tool - SWAT) and the data-driven model (Artificial Neural Network - ANN). The performance of the models was evaluated by the Nash-Sutcliffe coefficient (NSE), coefficient of determination (R2) and flow-duration-curves (FDC). The results indicate that SWAT (NSE &gt; 0.61; R2 &gt; 0.68) and ANN (NSE &gt; 0.91; R2 &gt; 0.79) models are suitable tools in daily streamflow modeling of the studied basin, with the ANN model being the most accurate. Based on FDC, the ANN model was also better than the SWAT model for all frequencies evaluated. ...

5.5.1. Análisis de la distribución espacial con Método de Kriging 232 5.5.2. Análisis de los iones mayoritarios con el software AqQa 5.5.3. Análisis de las cargas que ingresan por el Río Primero con el software Clarck 235 6. RESULTADOS Y DISCUSIÓN 6.1. Clasificación del agua del río y de la laguna 6.2. Estimación de la carga de nutrientes que aporta el río Primero 257 6.2.1. Estimación de la carga de material en suspensión (MES) que aporta el río Primero 268 Claudia E. Oroná XIV 6.3. Análisis de la variación temporal y espacial de los parámetros más importantes medidos en la laguna 271 6.3.1. Fósforo total y fósforo reactivo soluble 271 6.3.1.1. Fósforo total 6.3.1.2. Fósforo reactivo soluble 6

Metodi per la determinazione delle portate di piena: generalità sulle piene, trasformazione afflussi - deflussi (l'operatore bacino), modelli di trasformazione afflussi - deflussi, modelli concettuali a valenza limitata (modelli analitici), metodo cinematico, osservazioni e critiche al metodo cinematico, metodo del volume di invaso, osservazioni e critiche al metodo del volume di invaso, osservazioni conclusive e confronti dei metodi, metodo del coefficiente udometrico, metodo dell'idrograma unitario istantaneo (iuh), metodo dell'idrogramma unitario (uh), esempi di calcolo.

As mudancas climaticas deverao ter graves consequencias sociais e economicas. No entanto, poucos estudos tem avaliado o impacto das incertezas da mudanca climatica na disponibilidade hidrica de complexos sistemas de redes de reservatorios. A incerteza e agravada quando os reservatorios nao possuem monitoramento das vazoes afluentes. Nesses casos, a regionalizacao dos parâmetros de modelos hidrologicos representa uma estrategia comum para se estimar as vazoes afluentes. Propagar as incertezas associadas aos parâmetros para as bacias nao monitoradas apresenta-se, no entanto, como um desafio metodologico ainda em discussao. Neste estudo, propoe-se uma estrategia de regionalizacao, baseada no metodo de classificacao K-Nearest-Neighbor (K-N-N), que incorpora explicitamente as incertezas associadas aos parâmetros do modelo hidrologico. Tais incertezas, bem como aquelas provenientes da mudanca climatica, foram propagadas para as bacias nao monitoradas dos reservatorios no estado do Ceara, ...

The present study has the objective of investigating the hypothesis of stationary behavior in the streamflow regime of the upper Juruá river basin. For this purpose, the annual maximum daily flow data recorded at stations located in Cruzeiro do Sul and Marechal Thaumaturgo, AC, Brazil, were analyzed using the Mann-Kendall, Pettitt, and Spearman’s Rho tests. The results show sufficient evidence to conclude that, in Cruzeiro do Sul, the flow rates present an ascending temporal behavior, while in Marechal Thaumaturgo it is descending. However, this tendency is not significant (p&lt;0.05), allowing to conclude in favor of the stationarity hypothesis in the streamflow series of the referred basin. Thus, one of the physical implications associated to the results obtained may be the conclusion that the streamflow regime in the Upper Juruá basin has not changed significantly over time.

Multivariate frequency distributions are being increasingly recognized for their role in hydrological design and risk management. The conventional multivariate distributions are severely limited in that all constituent marginals have to be from the same distribution family. The copula method is a newly emerging approach for deriving multivariate distributions which overcomes this limitation. Use of copula method in hydrological applications has begun only recently and ascertaining the applicability of different copulas for combinations of various hydrological variables is currently an area of active research. Since there exists a variety of copulas capable of characterizing a broad range of dependence, the selection of appropriate copulas for different hydrological applications becomes a non-trivial task. This study evaluates the relative performance of various copulas and methods of parameter estimation as well as of recently developed statistical inference procedures. Potential copulas for multivariate extreme flow and rainfall processes are then identified. Multivariate hydrological frequency analysis typically utilizes only the concurrent parts of observed data, leaving a lot of non-concurrent information unutilized. Uncertainty in distribution parameter estimates can be reduced by simultaneously including such nonconcurrent data in the analysis. A new copula-based "Composite Likelihood Approach" that allows all available multivariate data of varying lengths to be combined and analyzed in an integrated manner has been developed. This approach yields additional information, enhancing the precision of parameter estimates that are otherwise obtained from either purely univariate or purely multivariate considerations. The approach can be advantageously employed in limited hydrological data situations in order to provide significant virtual augmentation of available data lengths by virtue of increased precision of parameter estimates. The effectiveness of a copula selection framework that helps in an a priori short listing of potentially viable copulas on the basis of dependence characteristics has been examined using several case studies pertaining to various extreme flow and rainfall variables. The benefits of the composite likelihood approach in terms of significant improvement in the precision of parameter estimates of commonly used distributions in hydrology, such as normal, Gumbel, gamma, and log-Pearson Type III, have been quantified.

Water is fundamental to maintain life on the planet. Besides, water in sufficient quantity and with adequate quality is also a requisite for human activities in its multiple uses: human and animal consumption, health, agriculture, industry, energy generation, transportation, leisure and recreation, sewage, and effluent dilution, among others. Therefore, correct water resources management becomes crucial to the development of the countries and regions as well to conservation and maintenance of water sustainable for present and future generations.In this perspective, the

The aim of this study was to select and apply appropriate methods for evaluating hydrological drought in the mountainous Bohemian Forest region. The results from individual hydrological profiles were compared with each other, followed by a general comparison of catchment areas in the extramontane region. The threshold and Gumbel (1963) methods, and a calculation of scarcity volumes, were used. In this way, dry days and episodes were defined, seasonal charts were compiled, and trends were assessed using the Mann–Kendall and Hirsch–Slack trend tests. It was found that the seasonality of the hydrological droughts on the windward and leeward sides of the mountains differed significantly. The maximum number of dry days was found to occur in the windward profiles in autumn and in the leeward profiles in winter. The amount of winter drought decreases with decreasing altitude. Significant decreases in the occurrence of hydrological drought were found in all profiles for the observed period.

The design of combined sewage system networks is based on the sanitary discharge (domestic, industrial) and the runoff generated by rainfall. The Egyptian code of practice for designing potable water and sewage networks gives two Intensity-Duration-Frequency (IDF) equations to calculate the intensity of rainfall to be applied to all cities of Egypt. The purpose of this research is to study and assess the adequacy of the rainfall intensity equations suggested by the aforementioned Egyptian code. This is carried out taking into consideration the available rainfall ground station measurements and remote sensing Tropical Rainfall Measurement Mission (TRMM) satellite rainfall estimates. This assessment leads to the following results. For the Mediterranean coastal cities, the code of practice equations significantly underestimates the rainfall intensities for all storm durations, which may lead to road networks damage and accidents due to hydroplaning and road flooding. On the contrary, f...

The availability of data is an important aspect in frequency analysis. This paper explores the joint use of limited data from ground rainfall stations and TRMM data to develop Intensity Duration Frequency (IDF) curves, where very limited ground station rainfall records are available. Homogeneity of the means and variances are first checked for both types of data. The study zone is assumed to be belonging to the same region and checked using the Wiltshire test. An Index Flood procedure is adopted to generate the theoretical regional distribution equation. Rainfall depths at various return periods are calculated for all stations and plotted spatially. Regional patterns are identified and discussed. TRMM data are used to develop ratios between 24-hr rainfall depth and shorter duration depths. The regional patterns along with the developed ratios are used to develop regional IDF curves. The methodology is applied on a region in the NorthWest of Angola.

Soil erosion is considered as one of the major causes of land degradation and reservoir sedimentation. Therefore, modeling of runoff and sediment yield at the catchment level is necessary. In this study, an attempt was made to simulate runoff and sediment yield of hydrologically similar basins of Kali River and Aghanashini River which joins west coast of India. A conceptual, continuous time and semidistributed SWAT2012 (Soil and Water Assessment Tool) model was selected for the modeling purpose. For the last two decades, Kali river basin experienced a very high rate of soil erosion due to various developmental activities in the basin. Therefore, it is essential to identify the soil loss within the basin. There are five dams constructed across the Kali river basin for various purposes. The presence of these reservoirs regulates stream flow and thus sediment load in the basin. However, the free movement of water across the Aghanashini river catchment leads to the unobstructed passage of sediments to the river mouth, as the catchment is not disturbed by the reservoir. This study deals with the impacts of the dams on stream flow, sediment load and the response of shoreline. Digital Shoreline Analysis System (DSAS) tool was used to analyze the shoreline changes. Simulated and observed values of runoff are compared, and calibration and validation were done for the basins using SWAT-CUP. Analysis of calibration and validation results shows that the model has a good performance. Therefore, the SWAT model can be used to conduct further studies in these study areas. Sediment yield obtained at the catchment outlet was 1.07 t/ha/year and 4.58 t/ha/year for Kali and Aghanashini basins, respectively. Less

Urban flooding is a major social and economic problem of any nation. The social implication is attributed to loss of lives and property, unwanted displacement and emotional disturbance attached. While that of economic problem is the cost of mitigation of flood and the aftermath solution. Thus, storm water drainage is part of essential modern city infrastructure. The need for proper analysis and design of drainages and other road water facilities cannot be overemphasized. To achieve this, critical analysis of available rainfall data, which is a key input, is required. A 35 years daily rainfall data were obtained from NIMET, from which the analysis was carried out using frequency method. The output generated are presented in graphical forms and model. Ultimately, an IDF curve generated, depicts Abuja rainfall pattern from which a 3-parameter model equation, I = 37Tr0.2 (t + 0.1)−0.9 was formulated. This is site or location specific. The curve and/or the formulated model can be adopted...

The Yom River is subjected to flooding and drought for six months each year. Several studies suggested storing water during the rainy season for use in the dry season. None of them, however, quantified the precise amounts of storage needed along the river with acceptable risks. In an attempt to quantify the required storage, we performed frequency analyses to learn the severity of streamflow droughts along the river. A deficit volume, defined as when the amount of flow is less than a selected threshold level, was used to characterize a drought event. The Weibull distribution model was chosen for analysis after comparison of log normal and Pareto models with an empirical distribution. Results showed a more severe drought condition exists towards the downstream section of the river where paddy fields are larger. A large deep groundwater irrigation project located near the mid-section of the river mitigates drought along this section. Drought is more severe further downstream from the project. One reason for this is that the baseflow is cut off by groundwater abstraction. This method presented can help to quantify the severity of hydrological drought along any river so that drought management measures can be undertaken.

Convolutional Neural Network (CNN) is an effective Deep Learning (DL) algorithm that solves various image identification problems. The use of CNN for time-series data analysis is emerging. CNN learns filters, representations of repeated patterns in the series, and uses them to forecast future values. The network performance may depend on hyperparameter settings. This study optimizes the CNN architecture based on hyperparameter tuning using Particle Swarm Optimization (PSO), PSO-CNN. The proposed method was evaluated using multivariate time-series data of electronic journal visitor datasets. The CNN equation in image and time-series problems is the input given to the model for processing numbers. The proposed method generated the lowest RMSE (1.386) with 178 neurons in the fully connected and 2 hidden layers. The experimental results show that the PSO-CNN generates an architecture with better performance than ordinary CNN.

The present study has the objective of investigating the hypothesis of stationary behavior in the streamflow regime of the upper Juruá river basin. For this purpose, the annual maximum daily flow data recorded at stations located in Cruzeiro do Sul and Marechal Thaumaturgo, AC, Brazil, were analyzed using the Mann-Kendall, Pettitt, and Spearman’s Rho tests. The results show sufficient evidence to conclude that, in Cruzeiro do Sul, the flow rates present an ascending temporal behavior, while in Marechal Thaumaturgo it is descending. However, this tendency is not significant (p&lt;0.05), allowing to conclude in favor of the stationarity hypothesis in the streamflow series of the referred basin. Thus, one of the physical implications associated to the results obtained may be the conclusion that the streamflow regime in the Upper Juruá basin has not changed significantly over time.

In poorly gauged regions, rainfall data are often short or even absent, hindering the possibility of estimating Intensity-Duration-Frequency (IDF) relations with operationally acceptable accuracy. In this research, a novel idea is presented for the use of three separate rainfall datasets: maximum annual daily data, monthly data and Tropical Rainfall Measuring Mission (TRMM) satellite data to develop robust IDF in Namibe, south of Angola. TRMM data is used to derive relations between maximum monthly and maximum daily rainfall and between sub-daily and daily rainfall depths. Frequency analysis is undertaken on the mixed daily record using several distributions and the best fitting is selected based on discriminant plots of the distribution tails and the moment ratio diagram as well as Bayesian criteria. The IDF curves are derived based on the estimates of daily rainfall at various return periods, with the derived sub-daily rainfall duration ratios. Robust IDFs are thus developed for a scarce data region in Africa.

Experimental tests were carried out to investigate the effective scouring parameters downstream from stepped spillways with different flow rates and step sizes. The results indicated that the flow regime plays an important role in scour-hole dimensions such that the minimum scouring depth happens in the nappe flow regime. Moreover, step size and tailwater depth are essential parameters for maximum scouring depth. Increasing tailwater depth from 6.31 cm to 8.54 cm and then to 11.82 cm decreases the scouring depth by 18.56% and 11.42%, respectively. These alterations also decrease the scouring length by 31.43% and 16.55%, respectively. By increasing the flow rate, the particle Froude number will increase, and the increased momentum of the flow promotes scouring. In addition, the results show that scouring at the sidewalls is higher than in the middle of the cross-section. Finally, an empirical formula with root mean square error = 0.107 and R2 = 0.974 is proposed to predict the maximu...

Tide level forecasting plays an important role in environmental management and development. Current tide level forecasting methods are usually implemented for solving single task problems, that is, a model built based on the tide level data at an individual location is only used to forecast tide level of the same location but is not used for tide forecasting at another location. This study proposes a new method for tide level prediction at multiple locations simultaneously. The method combines nonlinear autoregressive moving average with exogenous inputs (NARMAX) model and recurrent neural networks (RNNs), and incorporates them into a multi-task learning (MTL) framework. Experiments are designed and performed to compare single task learning (STL) and MTL with and without using non-linear autoregressive models. Three different RNN variants, namely, long shortterm memory (LSTM), gated recurrent unit (GRU) and bidirectional LSTM (BiLSTM) are employed together with non-linear autoregressive models. A case study on tide level forecasting at many different geographical locations (5 to 11 locations) is conducted. Experimental results demonstrate that the proposed architectures outperform the classical single-task prediction methods.

Being generally described as coherent entities in hydrological sense, watersheds are considered as study units to assess hydrological cycles and to come up with water management strategies. Hydrological modeling is a tool that can offer the chance to achieve these goals. The model Soil and Water Assessment Tool (SWAT) has been widely used in various parts of the world to support decision making on water management, and proved its efficiency in many arid and semi-arid areas even when different economical activities are held in the watershed (farming, pasture, forestry...). In this study, the SWAT model has been applied over R'dom watershed, agro-sylvo-pastoral basin located in a semi-arid area in NorthWestern Morocco, with the aim to simulate the hydrological processes occurring in the study basin as a preliminary step. The simulation was performed across the period 2004 to 2009 and gave satisfactory goodness-of-fit levels in daily time step (NSE= 0.58, R 2 = 0.79, PBIAS=19% during calibration and NSE=0.65, R 2 = 0.73, PBIAS=20% during validation). The results of the study showed that the water balance in R'dom watershed is dominated by evapotranspiration (61% of rainfall); surface runoff and water yield represent 8.3% and 25.2% of rainfall respectively. The water resources distribution within the watershed is uneven and follows a decreasing gradient matching the flow direction. The SWAT model succeeded to reflect the different hydrological processes in the study watershed and can be used to build integrated watershed management strategies within the studied basin and in other similar contexts.