RAINFALL-RUNOFF MODELING FOR THE ASSESSMENT OF RENEWABLE WATER RESOURCES OVER MOROCCAN WATERSHEDS: SEBOU, MELOUYA, SOUSS, BOUREGRAG, TENSIFT, AND OUM ER RBIA

The management and the assessment of water resources is a key factor for economic growth and sustainable development, particularly in water-scare regions such as the Middle East and North Africa (MENA). For a better understanding of the hydrological settings and the water potentialities in Morocco, we developed rainfall-runoff models across the six main watersheds of Morocco. Such an understanding is essential for developing exploration programs and sustainable management programs for Morocco’s water resources. The described research activities were accomplished in the framework of the “Building Opportunity of Science and Technology” (BOOST) workshop by the trained twelve young scientists from Egypt and Morocco.

The selected watersheds are Sebou (38,833 km²), Souss (17,141 km²), Tensift (20,369 km²), Oum Er Rbia (37,881 km²), Melouya (55,911 km²) and Bouregrag (9,832 km²). All six watersheds originate in the Atlas Mountains and discharge either into the Mediterranean Sea (Melouya) or into the Atlantic Ocean (Sebou, Bouregrag, Tensift and Souss). In order to understand the different hydrological responses of the six watersheds, we developed six rainfall-runoff models using SWAT model (Soil Water Assessment Tool). The adopted methodology heavily relies on public domain databases. We extracted the soil types from the Harmonized World Soil Database version 1.2, topography from the SRTM digital elevation database, the landuse classes from the USGS Global Land Cover Characterization database, and daily climatic data from 23 gauges (i.e. precipitation, wind speed, solar radiation, temperature and relative humidity) across the country provided by NOAA.

Preliminary results of simulated models from 2000-2010 indicate that the Sebou watershed receives the largest amount of renewable water resources and Souss receives the least. The average yearly renewable surface water resources over the entire area of the watershed are: 5.6 x 10⁹m³ (Sebou), 3.7 x 10⁹m³ (Melouya), 2.9 x 10⁹m³ (Oum Er Rbia), 1.7 x 10⁹m³ (Bouregrag), 1.5 x 10⁹m³ (Souss) and 1.3 x 10⁹m³ (Tensift). The potential renewable groundwater resources per year are 10.4 x 10⁹m³ (Sebou), 10.8 x 10⁹m³ (Melouya), 6.8 x 10⁹m³ (Oum Er Rbia), 2.7 x 10⁹m³ (Bouregrag), 1.8 x 10⁹m³ (Souss) and 3.0 x 10⁹m³ (Tensift).