A Suite of Tools for Analyzing Hydrology and Geomorphology in Impounded Rivers

Large impoundment dams have well-documented impacts on hydrologic and geomorphicfunction. Numerous tools and metrics have been developed over time to characterize theseimpacts, but they remain disparate, are often applied in a small number of studies, and rarelyapplied in concert with each other. Utilizing the open-source programming language R, Iassemble a suite of metrics known as DAMS – the Dam Analysis and Metrics Suite – thatcombines several pre-existing metrics for characterizing dam impacts into one script. Thesemetrics include the Indicators of Hydrologic Alteration to characterize hydrologic change; themean streambed elevation to characterize vertical change in the river; and sediment mass balanceand flood magnitude reduction. By combining these schemas, DAMS provides a flexible andcomprehensive way to characterize the impact of dams on hydrology and geomorphology.I apply DAMS to two dams in diverse geographic settings: the Buford Dam on theChattahoochee River in Georgia and the Harris Station Dam on the Kennebec River in Maine.Both are hydroelectric dams with long stream gage records before and after dam construction. Ifound that the Buford Dam has caused a decrease in high flows in the Chattahoochee River aswell as a change in the seasonality of flows. I found that the Kennebec River has seen anincrease in high and peak flow volume after the construction of the Harris Station Dam, but thisincrease is less than comparable unimpounded rivers. The geomorphic data the ChattahoocheeRiver is fairly limited and cannot be access for the Kennebec River at all, meaning that DAMSwas unable to tell a complete story about how these rivers changed due to impoundment,highlighting the need for increased monitoring on all of the United States’ rivers.