Water availability: spatially distributed analysis and evaluation of input variables

Abstract

ABSTRACT The simplicity of the water balance equation contrasts with the difficulty of determining the value of each of the variables involved, especially in basins with few or no records. At the same time, the determination of water availability at large temporal and spatial scales does not identify the regions with the highest pressure on it, so it is of interest for the development of water management and use plans to know the spatial variation precipitation (the principal source of water), evapotranspiration (the primary precipitation loss), as well as water demand. This study applies the water balance equation to determine the spatially distributed water availability. Methods for calculating evapotranspiration (Turc and Thornthwaite) and runoff (curve number, runoff coefficient, and Thornthwaite monthly calibration) are compared. The results show differences between the mountainous and rainy areas of the basin. The low area near the sea is flatter, has less rainfall, and concentrates most of the agricultural activity. The latter are areas with water scarcity, although, on average, the entire basin has water availability.