Caractéristiques statistiques de la crue régionale en Afrique de l'Ouest

Les estimations de débit de crue pour diverses périodes de retour peuvent être nécessaires à des sites à aménager où les hydrologues et les ingénieurs ne disposent pas de mesures de débit. Dans ce cas une analyse régionale peut s'avérer particulièrement utile. L'étude décrite dans cet article, s'appuie sur des chroniques de crues maximales provenant de 224 stations de jaugeages réparties sur l'ensemble de l'Afrique de l'Ouest. Un total de 42OO stations-années a été emloyé pour déduire les relations régionales entre la crue annuelle, la superficie du bassin et les précipitations annuelles moyennes. Ces données permettent d'évaluer les courbes de fréquence de la crue régionale sans dimension. (Résumé d'auteur

Driving forces of future water availability and water use within Europe

This paper provides the first opportunity to inform the British hydrological community of the aims and objectives of a collaborative project to develop and evaluate European water scenarios up to 2050. The emphasis is on identifying driving forces and key issues, relating primarily to socio-economic developments, that might influence future water availability and sectoral water demand within Europe, and so inform the scenario development process. These are population and economic growth, agricultural development and technological developments, as well as climate change and land use change, and also national and European policies and legislation. The outputs from the project should make a significant contribution to the development of water policy within Europe through more reliable assessments of future impacts of climate and other changes upon water resources, which, in turn, will improve the cost-effectiveness of adaptation and mitigation strategies for sustainable development

Caractéristiques statistiques de la crue régionale en Afrique de l'Ouest

Les estimations de débit de crue pour diverses périodes de retour peuvent être nécessaires à des sites à aménager où les hydrologues et les ingénieurs ne disposent pas de mesures de débit. Dans ce cas une analyse régionale peut s'avérer particulièrement utile. L'étude décrite dans cet article, s'appuie sur des chroniques de crues maximales provenant de 224 stations de jaugeages réparties sur l'ensemble de l'Afrique de l'Ouest. Un total de 42OO stations-années a été emloyé pour déduire les relations régionales entre la crue annuelle, la superficie du bassin et les précipitations annuelles moyennes. Ces données permettent d'évaluer les courbes de fréquence de la crue régionale sans dimension. (Résumé d'auteur

Flood regimes in the Southern Caucasus: the influence of precipitation on mean annual floods and frequency curves.

Relations between mean annual flood estimates and basin area and precipitation, as well as dimensionless flood frequency curves, have been derived from a number of groups of gauging stations in the southern Caucasus. Total precipitation and its seasonal distribution are extremely variable at this location. The importance of antecedent soil moisture deficit (closely linked to the seasonal distribution of precipitation) in determining the shape of flood frequency curves is discussed through previous empirical studies and recent sensitivity analyses. The varying shape of regional curves from the southern Caucasus is related to the variations in soil moisture defici

Modelling indicators of water security, water pollution and aquatic biodiversity in Europe

The GWAVA (Global Water AVailability Assessment) model for indicating human water security has been extended with a newly developed module for calculating pollutant concentrations. This module is first described and then illustrated by being used to model nitrogen, phosphorus and organic matter concentrations. The module uses solely input variables that are likely to be available for future scenarios, making it possible to apply the module to such scenarios. The module first calculates pollutant loading from land to rivers, lakes and wetlands by considering drivers such as agriculture, industry and sewage treatment. Calculated loadings are subsequently converted to concentrations by considering aquatic processes, such as dilution, downstream transport, evaporation, human water abstraction and biophysical loss processes. Aquatic biodiversity is indicated to be at risk if modelled pollutant concentrations exceed certain water quality standards. This is indicated to be the case in about 35% of the European area, especially where lakes and wetlands are abundant. Human water security is indicated to be at risk where human water demands cannot be fulfilled during drought events. This is found to be the case in about 10% of the European area, especially in Mediterranean, arid and densely-populated areas. Modelled spatial variation in concentrations matches well with existing knowledge, and the temporal variability of concentrations is modelled reasonably well in some river basins. Therefore, we conclude that the updated GWAVA model can be used for indicating changes in human water security and aquatic biodiversity across Europe