HYDROBIOLOGY

Author: Contreras López Sergio.
Year: 2005.
University: ALMERÍA [www.ual.es].
Place of defense: F.Ciencias Experimentales.
Place of preparation: Estación Experimental de Zonas Áridas, CSIC.

Summary: The preliminary evaluation of available water resources is one of the objectives of the water resource planning in arid regions where groundwater is the main source of supply. To achieve the goal of long-term balance between recharge and pumping from an aquifer, it requires the development and application of methodologies for calculating the annual water balance, especially in areas where the charge, generally mountainous. The overall aim of the thesis is to develop a methodological approach simple and moderate cost for the evaluation of water balance spatially distributed annually in arid mountainous regions. The model has been applied to different periods of precipitation type in Sierra Gádor, main area of aquifer recharge lower Field Dalías (Almeria). The annual water balance equation in arid regions can be simplified calculation of the difference between precipitation and evapotranspiration -E-. For the calculation of precipitation has been used statistical analysis and interpolation techniques. The estimate of evapotranspiration is based on the assumption hydrological balance. This assumption allows estimating E from NDVI and prior knowledge of two boundary conditions whose values NDVI and E are considered baseline. For the estimated NDVI in the boundary conditions is proposed empirical approximation that runs at regional and evaluating the deviation spatial spectral index is along a gradient climate. For the estimation of the values of E on the boundary conditions is the assumption balance Specht. Using this hypothesis requires monthly rainfall maps and potential evapotranspiration. For the first generation has ordered series of monthly rainfall several weather stations located in the study area. The average precipitation for three periods of precipitation type (dry years, average year and year moist) were interpolated spatially using a multivariate analysis with descriptive variables. To obtain maps of potential evapotranspiration was used calibrated equation of Hargreaves-Samani. The calibration equation Hargreaves-Samani was conducted with reference evapotranspiration values measured at stations located in the vicinity of the study area. Both assumptions have been contrasted with simulated and experimental data. Four images Landsat7 ETM + has been purchased, edited and processed for the calculation of the estimate of NDVI and E. The methodological approach is to identify areas with strong local water deficit and potential areas of recharge. The evapotranspiration spatially - averaged Sierra Gádor represents 70% of the annual precipitation (159 hm3/año). The low values of surface water found experimentally suggest that the remaining 30% corresponds to deep percolation or recharge potential. For a year and a wet dry years, the fraction not evapotranspirada is 36% higher and 27% lower, respectively, the average value of a year's precipitation medium. The potential predictive model has been verified in the Llano of Juanes, a representative area of the highlands of the Sierra Gádor. The calculated annual evapotranspiration overestimates by 8%, the measured value with the swirling correlation technique. The maximum error spatially averaged for the whole of Sierra Gádor is about 28%. A sensitivity analysis warns of the importance of correctly characterize the density of vegetation or NDVI, especially when 8 defined 2a9 on the terms of reference.