Soil conservation needs in the upper Mahaweli Catchment Watershed Management Project [Sri Lanka]

afforestation agentes nocivos asia asie boisement conservation conservation des ressources conservation des sols erosion control facteur nuisible forestry operations geologia geologie geology geomorfologia geomorphologie geomorphology injurious factors manejo del suelo methode methods mise en valeur du sol operaciones forestales procesamiento processing resource conservation sedimentation soil conservation soil management traitement