Some Examples Of Water Resources Variability In The Context Of Climatic Fluctuations
Abstract
The determination of the impact of climate change on hydrological systems and their water resource constitutes a major stake of the 21st century to which the scientists must answer. First of all, it is necessary to understand how climate are expressed in the hydrosystems. For several years, the M2C laboratory of the University of Rouen has tried to answer this question by working within the framework of many regional, national and international programs as well as PhD works. Those studies involve analyses of hydrological systems located: (1) in various climatic and geomorphological contexts on both sides of the Atlantic Ocean, (2) in various hydrological compartments (surface and ground water), (3) at various spatial scales (watersheds smaller than 1000 km2 and large rivers). The approach consists in studying the long-term changes, oscillations and fluctuations of hydrologic variables by the analysis of time series (precipitation, discharge, piezometry), in particular by means of signal analysis and processing methods. The studied hydrosystems are small watersheds and aquifer in Haute- Normandie, the Seine river (NW France), north-african watersheds (W Morocco and N Algeria), small watersheds and aquifer in Texas, the Colorado river (Texas) and the Mississippi river. Although the identification of structured variations might be uneasy - sometimes just impossible - in raw data, wavelet analysis, for instance, makes it possible to detect localized energetic structures and possible periodicities in all the studied hydrosystems and to quantify them. In many surface hydrosystems we note an intensification of the annual energy band which corresponds to the hydrological cycle. In the NW of France and North Africa, we observe 2-3-year and 5-7-year modes which could be linearly related to fluctuations in the NAO using wavelet coherence. In the USA, we notice similar 2- 3-year and 5-7-year modes that might be possibly related to the characteristic 2-4-year and 4-8-year of SOI. In any case, two major temporal discontinuities were systematically recovered around the 1970's and the 1990's characterized respectively by the occurrence of the 5-7-year and 2-3-year peaks. The above- mentioned intensification of the hydrological cycle is observed from 1990 up to now. These results would describe a global pattern in hydrological processes as a response to climate fluctuations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H21A0808L
- Keywords:
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- 1833 Hydroclimatology;
- 1840 Hydrometeorology;
- 1860 Streamflow;
- 1872 Time series analysis (3270;
- 4277;
- 4475);
- 1879 Watershed