干旱区生态环境知识资源中心

The Tambula-Picachos is a 390.22 Km(2) watershed situated in an arid land region, where almost 80,000 inhabitants are dedicated to tourism activities (urban areas), agriculture and livestock management (rural settlements). This paper aims to communicate the development of a participative and integrated approach for watershed management as a base line to cope with water scarcity and preventing natural risks derived from annual rainfall events. This approach was applied on two scales: the watershed and their nine micro-watersheds. Hydrological studies showed a short time concentration at the two scales (13 to 39 min for microwatersheds and 247 min to watershed) which indicated very fast hydrological responses. Vegetal cover has been altered for the last 100 years, conserved fragments are limited to the headwater areas, therefore erosion is moderate in about 70 % of the watershed, however 21% of the watershed area is under high erosion rates (500 ton/ha/yr), mainly in the watershed transition zone (the main water recharge area). Monitoring of runoff water in temporal streams and agricultural small reservoirs, showed moderate values of water quality, since poor peasant agricultural practices do not include agrochemicals use. Land and water management for agriculture are limited to basic techniques in the transition area of the watershed, in comparison to groundwater irrigation agriculture developed in the watershed alluvial valley, which is also affected by floodings on extreme rainfall events caused by stream channel modification, road construction and elimination of the riparian vegetation buffers. Participative commissions developed a Management Plan where habitants, academics and government representatives took decisions to maintain and improve quality of runoff water and watershed functioning working at the micro-watershed scale: maintain and restore vegetal cover, protect soils and offering alternative projects on water collection and its use to improve their life quality.