Doctoral Dissertation Research: The Effects of Run-of-River Dams on Stream Morphology

水坝在整个美国的河流系统中无处不在。对水坝的科学调查表明，水坝在上游蓄积沉积物，在下游严重侵蚀河道，其影响沿着河流，远离水坝。到目前为止，研究主要集中在大型蓄水大坝，忽略了较小的径流（非蓄水）大坝。由于对河流恢复的兴趣越来越大，需要了解河流大坝对地貌特征的原位影响，以预测大坝拆除对河流动力学的影响。这个博士论文研究项目调查如何运行的河流大坝影响河流地貌在伊利诺伊州的五个网站。本计画提出下列问题：（1）径流式水坝对水坝上下游河川系统有何影响？(2)本研究中所有水坝的这些影响有何异同？（3）径流坝与蓄水坝相比，其影响如何？ 该方法包括纵向和跨渠道地形测量和采样的床材料附近的每个大坝，并在控制网站以及上游。此外，将在每个水坝后面储存的沉积物中收集两个岩心，用于铯-137测定，以确定是否存在沉积物分层，作为这些水坝捕集效率的指标。初步的实地考察表明，地貌效果不同的水坝，尽管它们的位置在同一个自然地理区域内伊利诺伊州。将对该项目中获得的数据在各研究中心之间进行比较。它也将被收集的类似数据进行比较，在伊利诺伊州的蓄水大坝，以确定是否在两个大坝类型之间的地貌影响的差异是统计上显着的。预期的结果是，这些结构对地貌条件的影响的空间范围和程度将小于较大的大坝，并且大坝之间的影响将存在差异。本研究将有助于我们了解径流式水坝对河流地貌影响的空间范围和程度。了解河流大坝对河流系统的影响将有助于更好地预测大坝拆除后河流系统的反应。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

Dams are ubiquitous on river systems throughout the United States. Scientific investigations of dams have demonstrated that they impound sediment upstream, and significantly erode river channels downstream, with the effects proceeding along the river at distances far from the dam. Studies thus far have focused mainly on large impoundment dams, ignoring smaller run-of-river (non-impoundment) dams. Because of a growing interest in river restoration, knowledge of the in situ impacts of run-of-river dams on geomorphic characteristics is required to forecast the effects of dam removal on river dynamics. This doctoral dissertation research project investigates how run-of-river dams have impacted river geomorphology at five sites in Illinois. This project poses the following questions: (1) What is the impact of run-of-river dams on stream systems above and below each dam?; (2) What are the similarities and differences of these impacts across all dams in this study?; and (3) How do the effects caused by run-of-river dams compare to their impoundment counterparts? The methodology involves longitudinal and cross-channel topographic surveys and sampling of bed material near each dam, and at a control site well upstream. Additionally, two cores will be collected in the stored sediment behind each dam for Cesium-137 determination to ascertain whether sediment stratification exists, as an indicator of the trap efficiency of these dams. Preliminary site visits suggest that geomorphic effects differ among the dams, despite their location within the same physiographic region within Illinois. Data obtained in this project will be compared among the sites. It will also be compared to similar data collected for impoundment dams in Illinois to establish whether differences in geomorphic effects among the two dam types are statistically significant. The expected outcome is that the spatial extent and degree of impact of these structures on geomorphic conditions will be less than that for larger dams, and that variations will exist among the impacts across the dams. This research will contribute to our understanding of the spatial extent and degree of impact of run-of-river dams on river geomorphology. Understanding the effects that run-of-river dams have on stream systems will allow better forecasting of how a river system might respond once a dam is taken out. As a Doctoral Dissertation Research Improvement Award, this award will also provide support to enable a promising student to establish a strong independent research career.