Downstream Geomorphic Impacts of Large Dams on American Rivers

这项调查的目的是检查大型水坝对国家河流下游的影响。项目特别希望发展有关大坝安装和运行如何影响河道特征和河岸环境的新知识。具体问题包括与水坝规模和工程特性有关的下游河流功率的时空分布，以及运行规则。此外，还将从河道宽度、洪泛平原规模、河道形态和近河道地貌以及河岸生态系统的空间分布等方面评价河流动力分布的地理效应。该策略是将受水坝影响的实验河流河段的现状与附近没有水坝影响的类似控制河段进行比较，最多可达42座全国最大的水坝。调查方法侧重于使用统计技术对河流数据进行水文分析，使用GIS对航空摄影图像进行地理分析，以及实地调查收集沉积物和植被数据。该项目将推进目前关于淤积河流的河流理论，因为这种理论尚处于起步阶段，不包括对水坝的水文和地貌影响范围的概括。从应用的角度来看，这项工作将为河流对关键栖息地的影响提供新的信息。

The objective of this investigation is to examine the downstream impacts of large dams on the nation's rivers. In particular the PI wishes to develop new knowledge about how dam installation and operation have affected the characteristics of river channels and riparian environments. Specific questions include the temporal and spatial distributions of stream power downstream in relation to scale and engineering characteristics of dams, as well as, operating rules. In addition the geographic effects of distributions of stream power will be assessed from the perspectives of channel width, flood plain dimensions, channel patterns and near channel landforms, and spatial distributions of riparian ecosystems. The strategy is to compare present conditions on experimental river reaches that have been impacted by dams with nearby similar control reaches that are without such structures for up to 42 of the largest dams in the country. Methods of investigation focus on hydrologic analyses of streamflow data using statistical techniques, geographic analyses of aerial photographic images using GIS, and field investigations to collect sediment and vegetation data. The project will advance present fluvial theory for impounded rivers for such theory is in its infancy and does not include generalizations about the range of hydrologic and geomorphic impacts of dams. From an applied perspective the work will provide new information on the effect of rivers on critical habitat.