An assessment of the downstream impacts on a riparian corridor of employing Flow Assisted Sediment Transport (FAST) to remove sediment from a major Southern California Reservoir

摘要

The question of reservoir sustainability has taken on increased significance in the face of growing concerns regarding the need to ensure both adequate flood protection, and water supply storage capacity. The trend towards more extreme climatic conditions, urbanization and the growing need for assured water supplies for growing populations has served to add a level of urgency to this issue. Central to this matter is the need to remove sediment from reservoirs in order to restore storage capacity and in many cases maintain operational control. The challenge is to do so in a cost effective, sustainable, and environmentally acceptable manner. This paper presents the results of an operational experiment in which the downstream impacts and viability of using carefully managed Flow Assisted Sediment Transport (FAST) to not only remove sediment from a major reservoir but also convey sediment through a 10 km riparian corridor. The experiment conducted on Morris Reservoir, Morris Dam and San Gabriel River System in Southern California effectively moved some 350,000 m~3 out of the reservoir and down through the river system with minimal environmental impact, at a total cost below $1.30 US/m~3. The methodology and monitoring system employed are presented below with particular attention to monitoring the sedimentological and environmental impacts on the downstream riparian corridor.