Impact of land use in catchment and human activities on water, sediment and vegetation of Mediterranean temporary pools

The vegetation and physical and chemical characteristics of the water and s ediment in ten temporary pools submitted to various anthropogenic disturban ce were studied in Morocco over two hydrological cycles (1997-1998 and 1998 -1999). Results of multivariate and parametric analyses show that disturban ce has a significant impact on water and sediment. Agriculture in the catch ment resulted in higher levels of N and the use of detergent to higher leve ls of phosphorus in both water and sediment. Mineral extraction resulted in higher depth and longer duration of flooding. Vegetation characteristics w ere better correlated to hydrology (water depth, duration of flooding) than to nutrient variables. These results suggest that although agriculture in the catchment contribute in modifying the sediment characteristics, the imp act on vegetation and its conservation value is limited. However, care shou ld be taken of the long-term effects of agriculture through cumulative effe cts and of the possible consequences of changing the agricultural practices . (C) 2001 Academie des sciences/Editions scientifiques et medicales Elsevi er SAS.