| Title: | Modelling water-harvesting systems in the arid south of Tunisia using SWAT |
| Authors: | Ouessar, M., Bruggeman, A., Abdelli, F., R.H. Mohtar, D. Gabriels and W.M. Cornelis |
| Year: | 2009 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 13(10) |
| Pages: | 2003-2021 |
| Article ID: | |
| DOI: | 10.5194/hess-13-2003-2009 |
| URL (non-DOI journals): | |
| Model: | SWAT-WH |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | rainwater/water harvesting or utilization |
| Secondary Application Category: | model and/or data comparison |
| Watershed Description: | 272 km^2 Wadi Koutine, located in the Jeffara region in southeast Tunisia. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | In many arid countries, runoff water-harvesting
systems support the livelihood of the rural population. Little
is known, however, about the effect of these systems on the
water balance components of arid watersheds. The objective
of this study was to adapt and evaluate the GIS-based watershed
model SWAT (Soil Water Assessment Tool) for simulating
the main hydrologic processes in arid environments. The
model was applied to the 270-km^2 watershed of wadi Koutine
in southeast Tunisia, which receives about 200mm annual
rain. The main adjustment for adapting the model to this
dry Mediterranean environment was the inclusion of water harvesting
systems, which capture and use surface runoff for
crop production in upstream subbasins, and a modification
of the crop growth processes. The adjusted version of the
model was named SWAT-WH. Model evaluation was performed
based on 38 runoff events recorded at the Koutine
station between 1973 and 1985. The model predicted that
the average annual watershed rainfall of the 12-year evaluation
period (209 mm) was split into ET (72%), groundwater
recharge (22%) and outflow (6%). The evaluation coefficients
for calibration and validation were, respectively,
R2 (coefficient of determination) 0.77 and 0.44; E (Nash-
Sutcliffe coefficient) 0.73 and 0.43; and MAE (Mean Absolute
Error) 2.6mm and 3.0 mm, indicating that the model
could reproduce the observed events reasonably well. However,
the runoff record was dominated by two extreme events,
which had a strong effect on the evaluation criteria. Discrepancies
remained mainly due to uncertainties in the ob-
served daily rainfall and runoff data. Recommendations for
future research include the installation of additional rainfall
and runoff gauges with continuous data logging and the collection
of more field data to represent the soils and land use.
In addition, crop growth and yield monitoring is needed for
a proper evaluation of crop production, to allow an economic
assessment of the different water uses in the watershed. |
| Language: | English |
| Keywords: | |