IMPACTS OF FLOOD IMPOUNDMENTS ON WATER BALANCES OF DOWNSTREAM RIPARIAN CORRIDORS

摘要

Over 10,450 flood control dams have been built in 47 states. Many are nearing their design life of 50 years and have significant rehabilitation needs, the cost of which approaches over $540 million. While assessment of engineering safety is a major consideration, little is known about the effects of these structures on downstream riparian corridors. Detailed monitoring of local water budgets conducted downstream of one structure has verified links between the flow regime of the dam and riparian vegetation. Stream flow, soil water, and transpiration rates were measured in a downstream riparian community for a one-year period. This monitoring showed that riparian vegetation is linked directly to both the stream and the groundwater system. The riparian zone is enhanced by low flow release from the upstream structure in which plants utilize available stream water via a groundwater pathway. This positive feedback system has direct benefits for the downstream ecosystem through increased and constant water availability.