Water balance and hydropluviometric variability of dams in Eastern Algeria

ABSTRACT Eastern Algeria, the wettest region of the country, has experienced a vast program of dam construction, distributed across basins marked by strong physio-climatic disparities. The hydrological functioning studied through the use of data from the regulation balance sheet for the period from September 1990 to August 2013, concerned a sample of 10 dams (capacity varying from 3 to 200 hm³) whose year of impoundment varies from 1939 to 1987. The results of the statistical and spectral analysis applied to two main terms of the water balance (inputs and rainfalls) indicate a strong relationship between the studied parameters, reflecting a net increase in dry years from September 1990 to August 2002, with a return of wet years from the year 2003, however, interrupted by other very dry years like that of 2007/2008. The outflows (outputs) of the dams reflect considerable water losses in the form of evaporation and also in the form of leaks on karstic sites. However, it is the flood phenomena that are at the origin of remarkable overflows and bottom outlets. In addition to these losses, there are significant variations in the regulated volume of dams, particularly in semi-arid zones and during periods of drought, particularly.