Assessment of Groundwater Quality: Impact of Natural and Anthropogenic Contamination in Souss-Massa River Basin

Groundwater quality in Souss-Massa Basin is influenced by natural and anthropogenic contaminations. In fact, the geological formations are the main sources of mineralization in Souss-Massa aquifer. The impact of marine intrusion is noticed in the coastal area. However, human activities are also responsible for the deterioration of groundwater quality. Indeed, agriculture is the main activity in the region with the presence of some industrial food unities which contribute to the degradation of water quality due to different uses of water resources as well as the reject of industrial and urban wastewater. The evaluation of urban pollution shows that it is directly linked to demographic changes, the rate of connection to the sanitation system, and wastewater treatment. However, wastewater treatment activity is quietly growing in the area. In fact, more than six treatment plants are operational in different cities. Furthermore, the Hydraulic Basin Agency and its partners have initiated several studies for new treatment plant implementation in other locations. Despite this progress, sanitation sector is still in remarkable delay. In fact, the total liquid discharges through the Souss-Massa Basin are equal to 28.8 million m³ of which 54.7% are only treated, and 45% are rejected directly in the environment and consequently generating a pollution load of more than 7.1 T/year of BOD, for example. The Agadir City is generating more than 50% of this pollution load. Regarding the production of solid waste, the total amount of waste produced in the area is evaluated at nearly 565.000 T/year. The distribution of waste between provinces shows that for the urban area of Agadir and Inezgane Ait Melloul, agglomeration contributes with over 80% of waste, while Taroudant and Ait Baha contribute with 68%. The assessment of industrial pollution shows that 36% of potential polluting industries are located at the province of Chtouka Ait Baha, 35% at the province of Inezgane Ait Melloul, 24% at Taroudant, 4% at Tiznit, and 1% at the province of Agadir Ida Ou Tanane. Agriculture is the dominant activity in the basin where the agricultural pollution in the Souss-Massa Basin is mainly connected to the agricultural production and the livestock. Citrus and vegetables are considered as a main source of nitrate pollution because of the important quantities of fertilizers used for these crops. The pollution load based on amounts of nitrogen leached is valued at 1,511 tons of nitrates per year.