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sur le développement des zones arides et semi-arides

Titre : Evaluation of floodwater spreading for groundwater recharge in Gareh Bygone Plain, southern Iran

Auteur : Pakparvar, Mojtaba

Université de soutenance : Gent University

Grade : Doctor (PhD) in Applied Biological Science 2015

Résumé
The overall objective of this dissertation was to evaluate a floodwater spreading system that is installed in 1981 at the Gareh Bygone Plain, southern Iran for recharging the groundwater table. As the spatial and temporal distribution of the evapotranspiration (ET) was a necessary input, an energy balance model “SEBS” was calibrated for the study area and its results were cross checked with water budget results to obtain the reliable ET maps. TDR method was then evaluated for the original stony soils and a set of new coefficients were generated for these soils and the new equations for cable length correction for accurately converting the soil permittivity to ɵv. Two methods of recharge assessment “saturated zone” and “vadose zone” were further employed to determine the ratio between total and artificial recharge independently. In saturated zone, water table fluctuation and water budget concepts were combined and the effect of flooding event on groundwater table was substantiated and the recharge was assessed for a selected hydrological year. In vadose zone, three experimental well were installed with the depth of 30m and one was equipped with the calibrated TDR probes and the time series of soil-water data were collected for the three years successively. Soil water budget method and a modelling approach by Hydrus 1d was used independently to simulate the water movement and assess the recharge after a flooding event. Calibration of the H1D model by inverse solution resulted in RMSE values of simulated vs. observed ɵv of 0.02 to 0.05 (m3 m-3) for different subsurface layers. Calculations, indicated that out the 51.8 cm of ponded floodwater during the 16 January to 23 August 2011 period, 29.6 cm of cumulative recharge occurred, showing an efficiency of 57%. Two independent approaches suggest that 57 to 61% of input water effectively flows to the groundwater table. The optimized hydraulic parameters of the representative layers in aquifer profile, can be applied in future studies when attempting to up-scale our findings.

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