Study of the Relations Between Runoff, Weather Forecast and Watershed Evaporation in the South Mediterranean Region (Algeria Case)

Water resources in Algeria are not distributed evenly in space and time that engenders enormous difficulties for their mobilization. Water shortage is becoming a major problem. A number of regions already suffers from water deficiency and the others will soon follow. To solve this problem, the construction of new dams becomes indispensable. Through the hydrological studies and the exploitation of future dams, the evaluation of water yield in sites of these structures is indispensable. At present, the calculation of the interannual runoff in absence of data for the not gauged watercourse is determined from empirical formulae established especially for the climatic and geographical conditions of Algeria. Unfortunately, all these formulas do not provide accurate results. Watersheds which were used in the study represent almost the entire surface of Northern Algeria whose number is 106 basins. The objective of the present study is to establish working tools, allowing the planners and the managers to determine the value of the interannual runoff of watershed for the climatic conditions of Algeria without going through the empirical formulae often used in the absence of measurable data and leading to absurd errors. The calculation parameters for interannual runoff from the proposed model are standard meteorological data (air temperature, humidity and pluviometry), always available and periodically broadcasted by meteorological services and hydrology of Algeria. Runoff values calculated by the model are close to the values of measured runoff. The difference between them did not exceed 15 to 20 %.Original Abstract: Les ressources en eau de l'Algerie sont irregulierement reparties dans l'espace et dans le temps, ce qui engendre d'enormes difficultes pour leur mobilisation. Les penuries en eau sont en train de devenir un probleme majeur. Nombre de regions souffrent deje du deficit hydrique, d'autres suivront sans doute. Face a cette situation, la construction de nouveaux barrages devient indispensable. A travers les etudes hydrologiques et l'exploitation des futurs barrages, l'evaluation des apports de ces ouvrages aux sites est indispensable. Actuellement, le calcul du ruissellement interannuel en absence de donnees de mesure pour les cours d'eau non jauges est determine a partir des formules empiriques ne prenant pas en consideration des elements meteorologiques contribuant a la formation du ruissellement tels que la temperature et l'humidite de l'air. Malheureuse