The problems associated with floods,droughts,and degraded water quality are increasing worldwide.There is a growing recognition that these problems are caused,in part,by human impacts to watersheds.Land uses throughout each watershed directly influence the pathways and rates of water movement and therefore the hydrologic processes of runoff,groundwater infiltration,and evapo-transpiration.In particular,clearing away natural vegetated communities and replacing them with the impervious surfaces of roads,roofs and parking lots,and by more compacted soils having reduced organic matter,all contribute to increased runoff,greater evaporative losses,and less groundwater infiltration.