Global streamfl performance

Journal of Hydrometeorology, 2002

... Baumgartner and Reichel (1975, BR75 hereafter) derived global maps of annual runoff and made estimates of annual freshwater discharge largely based on streamflow data from the early 1960s analyzed by Marcinek (1964). ...

Hydrology and Earth …, 2006

Hydrol. Earth Syst. Sci., 10, 535–552, 2006 www.hydrol-earth-syst-sci.net/10/535/2006/ © Author(s) 2006. This work is licensed under a Creative Commons License. ... A global evaluation of streamflow drought characteristics ... AK Fleig1, LM Tallaksen1, H. Hisdal1,2, and S. ...

Hydrology and Earth System Sciences, 2017

The objective of this paper is to assess the performance of methods that predict low flows and flood runoff in ungauged catchments. The aim is to learn from the similarities and differences between catchments in different places, and to interpret the differences in performance in terms of the underlying climate-landscape controls. The assessment is performed at two levels. The Level 1 assessment is a metaanalysis of 14 low flow prediction studies reported in the literature involving 3112 catchments, and 20 flood prediction studies involving 3023 catchments. The Level 2 assessment consists of a more focused and detailed analysis of individual basins from selected studies from Level 1 in terms of how the leave-one-out cross-validation performance depends on climate and catchment characteristics as well as on the regionalisation method. The results indicate that both flood and low flow predictions in ungauged catchments tend to be less accurate in arid than in humid climates and more accurate in large than in small catchments. There is also a tendency towards a somewhat lower performance of regressions than other methods in those studies that apply different methods in the same region, while geostatistical methods tend to perform better than other methods. Of the various flood regionalisation approaches, index methods show significantly lower performance in arid catchments than regression methods or geostatistical methods. For low flow regionalisation, regional regressions are generally better than global regressions.

Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental

One of the main problems in the development of hydrological studies is the scarcity of measured data. In Brazil, because of its great water availability, and due to its territorial extension, the costs of implementing and maintaining hydrometric stations is a challenge, compromising hydrological monitoring and data collection. Therefore, developing methods that contribute to the estimation and transfer of information is essential for better integrated management of water resources, highlighting the importance of maximum streamflow data on issues such as flood mitigation. In order to solve this problem, streamflow regionalization models appear as tools to estimate hydrological data in ungauged sites, that is, it allows the transfer of measured or simulated information between homogeneous basins. In view of this, this article has the objective of investigate and describe the main methodologies developed and disseminated in the literature on hydrological regionalization, especially in ...

Water

Due to many uncertainties in hydrological data and modeling, the findings are frequently regarded as unreliable, especially in heterogeneous catchments such as the Kabul River Basin (KRB). Besides, statistical methods to assess the performance of the models have also been called into doubt in several studies. We evaluated the performance of the Soil and Water Assessment Tool (SWAT) model by statistical indicators including the Kling-Gupta efficiency (KGE), Nash–Sutcliffe efficiency (NSE), and the coefficient of determination (R2) at single and multi-outlets in the KRB and assessed the streamflow under changing climate scenarios i.e., Representative Concentration Pathways (RCP) 4.5 and 8.5 (2020–2045). Because of the heterogeneous nature of the KRB, NSE and R2 performed poorly at multi-outlets. However, the KGE, as the basic objective function, fared much better at single-outlet. We conclude that KGE is the most crucial metric for streamflow evaluation in heterogeneous basins. Simila...

Hydrological Sciences Journal-journal Des Sciences Hydrologiques, 2003

This contribution to the debate on the revision of rainfall and streamflow normals concerns three countries of West Africa: Burkina Faso, Ivory Coast and Mali. The rainfall deficit (15–20% on average in the study area) and the river flow deficit (about 30–50% and sometimes more) observed over the past 30 years in West and Central Africa raise the problem of the reference period that must be considered in estimates of hydrological characteristics. The hypothesis of the concept of “normal” supporting these estimates is a stability of the climate. However, the effect of taking or not taking into account the data of recent years on the estimates of these characteristics can lead to very different results. This would have serious consequences for the development and management of water resources systems, as seen in two examples of dams.Cette étude concerne trois pays d'Afrique de l'Ouest: le Burkina Faso, la Côte d'Ivoire et le Mali. Il s'agit d'une contribution au débat sur la révision des normes hydrologiques tant en matière de précipitations que de débits. Les déficits pluviométriques (de l'ordre de 15 à 20% en moyenne dans la région étudiée) et sur les débits (de 30 à 50% et parfois plus) observés durant ces 30 dernières années en Afrique de l'Ouest et Centrale soulèvent la question de la période de référence qu'il convient de retenir pour la définition des caractéristiques hydrologiques. Par définition, le concept de normes hydrologiques fait référence à une stabilité du climat. A l'opposé, le fait de prendre en compte, ou non, les données des années récentes pour estimer les caractéristiques hydrologiques peut conduire à des résultats très différents et à de sérieuses conséquences sur la conception et le fonctionnement des ouvrages équipant les bassins versants. Le cas de deux barrages est évoqué ici.

Proceedings of the International Association of Hydrological Sciences

Journal of Water and Climate Change

In recent decades, streamflow data remain inaccessible for most river gauges in Ethiopia due to a lack of updated stage–discharge relationships, also called rating curves. In this study, researchers and hydrologic technicians collaborated to fill the recent streamflow data gaps at three gauging stations in the Lake Tana sub-basin of the Nile River. We conducted extensive field campaigns to improve the coverage of stage–discharge measurements for rating curve development. We evaluated the rating curve uncertainty during the time of its establishment and the sensitivity of the rating curves to sample size. The stage–discharge measurements conducted by the hydrological agency during the period 2016–2020 were found inadequate in number and coverage to establish reliable rating curves. Hence, converting recent water level measurements to discharge data was made possible using the rating curves developed in this study. The converted discharge data will be accessible to researchers to inve...

Physics and Chemistry of the Earth, Parts A/B/C

Sustainable management of river basins requires precise understanding of the origin and variability of water fluxes. Water samples were collected in Thukela Basin (30,000 km 2), South Africa, over the 2012 rainy season, from fifteen 1 m 2 runoff microplots (for OF), a 5-m deep piezometer (SW) and 20-m deep borehole (GW), in the basin headwater and nested catchment outlets (microcatchment, 0.23 km 2 ; subcatchment, 1.20 km 2 ; catchment, 9.75 km 2 ; sub-basin, 253 km 2). The water samples were analysed for Sodium (Na) and Silica (Si) concentrations using an inductively coupled-plasma emission spectrophotometry. End Member Mixing Analysis (EMMA), with Na and Si as tracers, was then used to quantify the water compartment contributions to river flow. The results showed a general decrease of unit-area runoff in downslope direction from 5.7 to 1.2 L m −2 day −1 at microplot and microcatchment level, respectively, to 1.4 L m −2 day −1 at the basin outlet. OF contributions averaged 61% at microcatchment, 79% at subcatchment, 40% at catchment, 78% at sub-basin and 67% at the basin outlet, which corresponded to 0.82, 0.26, 5 × 10 −5 , 2 × 10 −3 and 9 × 10 −5 L m −2 day −1 , respectively. The respective SW contributions were 39% (0.38 L m −2 day −1), 18% (0.10 L m −2 day −1), 49% (5 × 10 −5 L m −2 day −1), 15% (4 × 10 −4 L m −2 day −1) and 33% (5 × 10 −5 L m −2 day −1). GW contributions were much lower at all spatial scales, but showed a general increase with increasing contributing surface area from microcatchment to subbasin outlet followed by a decrease to the basin outlet. The end-member contributions showed large spatial variations, hence longer-term research integrating more observation points is recommended to generate adequate data for development of prediction models for this important river basin. More research linking carbon, nutrient and pollutant fluxes to water dynamics is also recommended.