Modelisation of Water Balance by Simulation of Potential Evapotranspiration and the Rainfall for the Region of Annaba PDF

Keywords

water balance, rainfall, evapotranspiration

Abstract

The water balance modelling of the Annaba region is achieved by integrating the chronological series (20 years) of rainfall and potential evapotranspiration (ETP). Rain constitutes the main contribution in bringing water to the soil; it is included in the water balance in terms of the effective rain. The ETP allows us to quantify the crop's need for water. It determines the water volume lost by soil evaporation and plant transpiration and depends on atmospheric demand. on the stage of development of the vegetative cover as well as on the water supply. The water balance modelling, rainfall and potential evapotranspiration simulation are established on a daily basis. The rainfall following an aleatory phenomenon is simulated by the discreet Markov's chains. In fact, two states are taken into consideration: state 0: if the rainfall is inferior or equal to a previously determined threshold. state 1: if the rainfall is superior to that threshold. The potential evapotranspiration whose variations are cyclical is simulated by the decomposition of the historical series into seasonal and fluctuating components. These parameters (rainfall and potential evapotranspiration) enable the modelling of the water balance which allows to quantify the supply water volumes obtained by irrigation. The synthetic series of water deficits allow us to anticipate and to predict certain problems due to climate hazards thereby enabling water resource managers to avoid them.