Urban growth, liquid and pluvial sanitation problems in the Srou basin (Central Morocco) ; Croissance urbaine et problèmes d'assainissement liquide et pluvial dans le bassin du Srou (Maroc central)

International audience ; In Morocco, the scarcity of water resources is worsened by the deterioration of their quality caused by the liquid polluting emissions, whereas the natural ecosystems are threatened by the floods and by soil erosion. The problems of liquid and pluvial sanitation affect, first of all, the urban environment where the population of the poor districts accepts them more than the lack of drinking water. However, these problems give a bad image of towns where the rules of town planning are not respected. Generally, there is no correspondence between the development of housing and the expansion of liquid and pluvial sanitation system. The example studied here concerns the towns of the basin of Srou, an affluent of the upper Oum-er-Rbia. These towns are situated in an environment of middle mountain which suffers from a general lack of equipment. Instead of being completely collected, wastewater in these towns is poured into cesspools and ravines near the houses. The major part is poured into dry or severe low-water thalwegs. The impacts on people's health and the pollution of ground-waters and streams are extremely important. In this area, characterized by violent storms, especially during the warm season, floods are frequent. The steep slopes and their clayey and waterproof substratum accelerate the water run-off and its concentration into the hydrographic network which, sometimes, flows through the urban zones. The damages caused by floods are rarely compensated for. The poverty of the communes and of the populations, as well as the financial disengagement of the State bears negative impacts on space planning. ; Au Maroc, la pénurie des ressources en eau est aggravée par la détérioration de leur qualité sous l'effet des rejets polluants liquides tandis que les écosystèmes naturels sont menacés par les inondations et l'érosion des sols. Les problèmes d'assainissement liquide et pluvial affectent, en premier lieu, l'environnement urbain où la population des quartiers pauvres les supporte plutôt ...