Application and comparison of two analytical tools of decision support for the management of resources in a river basin in Tunisia
Author(s)
Sakka, Moez
Date Issued
March 11, 2011
Type
Doctoral Thesis
Abstract
The objective of this study was to adapt and evaluate the applicability of a physically-based
spatially distributed hydrological model SWAT (Soil Water Assessment Tool) and IWRM
integrated water resources management lumped model WEAP (Water Evaluation And
Planning) for simulating the main hydrologic processes in arid environments. The models
were applied to the 1200-km2 watershed of wadi Merguellil in central Tunisia to investigate
the hydrological response of the basin. The sensitivity analysis of hydrology, soil and
vegetation parameters of SWAT and WEAP helped to identify influential parameters and this
could serve as a guide in calibrating the models. The main adjustment for adapting WEAP
and SWAT model to this dry Mediterranean watershed was the inclusion of water soil
conservation works WSCWs, which capture and use surface runoff for crop production and
aquifers recharge in upstream basins. The models were run and the simulated runoff values
were compared with the measured stream-flow values. In the calibration period the Nash
efficiency coefficient for the SWAT and WEAP models were respectively 0,64 and 0,41 for
the runoff. The value of Nash coefficient indicates that the result of SWAT model is
acceptable contrasting the WEAP model. SWAT simulation was better than WEAP in most
case and could be used with reasonable confidence for runoff quantification in the Merguellil
watershed. For the SWAT model, The results of the water balance simulation at monthly and
annual time scales was generally good and the observed stream-flow in Zebess, Skhira,
Haffouz and El Houareb flow-gages could be reproduced satisfactorily. An estimation of the
suspended sediments and nutrients loads in the watershed was performed without calibration
because of missing data. Several hypothetical scenarios of land use and climate change were
generated by the SWAT and WEAP models in order to determine the impact of the variation
of land management and climate change on water demand and supply on downstream water
users.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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