Compilation of Data on the Middle Savannah River for the Analysis of Sub-Daily Flow Variation, 2011-2015

The Nature Conservancy (TNC) has been working with the U.S. Fish and Wildlife Service (USFWS), the U.S Army Corps of Engineers – Savannah District (USACE - Savannah) and other stakeholders on environmental flow recommendations for the Savannah River since May 2002 and have recently (2015) updated the environmental flow recommendations from 2003. Analysis of the flow data revealed a large amount of flow variability on sub-daily basis in the reach of the Savannah River from the Augusta Shoal downstream to the New Savannah Lock and Dam. The sub-daily flow variability affects sustaining suitable habitat during critical periods to promote fish spawning of robust redhorse, shad, and Atlantic sturgeon. The cause of the flow variability is hypothesized to be a result of the interaction of flow releases by two upstream hydroelectric facilities (Strom Thurmond Lake and Stevens Creek Hydroelectric Facility [Stevens Creek]) and backwater conditions. An important goal of the USACE Sustainable River Program (SRP) is to improve the health of rivers by changing the operations of reservoirs. Important tasks to meet this goal include work to: improve the understanding of existing hydrologic, ecological and socio-economic conditions at project sites; to refine environmental flow needs; and improve reservoir operations. To better understand how these upstream flow releases interact, a time-series database was compiled to evaluate the flows releases and the downstream variability. Stream temperature was included in the dataset because the sub-daily variability is more biologically critical during particular temperature ranges. Continuous monitoring data was obtained from the U.S. Geological Survey (USGS) and the USACE. The South Carolina Electric and Gas Company (SCE&G) provided data on the daily operation for Stevens Creek. The data were organized in monthly workbooks with one spreadsheet per day of the month. Scripts were written to parse the data from the various workbooks and spreadsheets into a continuous time series of hourly flow releases from Stevens Creek. The period for the compiled data set is January 1, 2011 to December 31, 2015. Time-series of time derivatives of daily change in flow at the USGS gaging station was computed. The measured and computed time-series data were compiled into a data viewer to facilitate the interrogation of the flow and temperature data and to visualize the interaction of the hydropower releases on downstream flow rates.

自然保护协会（The Nature Conservancy, TNC）自2002年5月起，便与美国鱼类及野生动物管理局（U.S. Fish and Wildlife Service, USFWS）、美国陆军工程兵团萨凡纳分局（U.S. Army Corps of Engineers – Savannah District, USACE - Savannah）及其他利益相关方合作，为萨凡纳河制定环境流量推荐方案，并于2015年对2003年版的环境流量推荐方案进行了更新。对流量数据的分析显示，在奥古斯塔浅滩至新萨凡纳船闸大坝下游的萨凡纳河河段内，存在大量亚日尺度的流量波动。此类亚日流量波动会在关键时期维持适宜栖息地，以促进壮红吸口鱼（robust redhorse）、西鲱（shad）以及大西洋鲟（Atlantic sturgeon）的产卵活动。研究推测，该流量波动的成因是两座上游水力发电设施——斯特罗姆·瑟蒙德湖水电站与史蒂文斯溪水电站（Stevens Creek Hydroelectric Facility, Stevens Creek）的流量泄放与回水条件的共同作用。美国陆军工程兵团可持续河流计划（USACE Sustainable River Program, SRP）的一项核心目标是通过调整水库运行方式，改善河流健康状况。为达成该目标，需开展的关键工作包括：加深对项目区域现有水文、生态及社会经济条件的认知，细化环境流量需求，以及优化水库运行方案。为更好地明晰上述上游流量泄放的相互作用机制，研究人员构建了时序数据库，用于评估流量泄放情况与下游流量波动。数据集纳入了河水温度数据，因为在特定温度区间内，亚日尺度的流量波动对生物的影响更为关键。连续监测数据来源于美国地质调查局（U.S. Geological Survey, USGS）与美国陆军工程兵团，南卡罗来纳州电力与燃气公司（South Carolina Electric and Gas Company, SCE&G）则提供了史蒂文斯溪水电站的日运行数据。所有数据被整理为月度工作簿，每月每日对应一张电子表格。研究人员编写了脚本程序，将来自不同工作簿与电子表格的数据解析为史蒂文斯溪水电站每小时流量泄放的连续时间序列。本次构建的数据集时间覆盖范围为2011年1月1日至2015年12月31日。研究人员还计算了美国地质调查局水文监测站的日流量变化的时间导数时序数据。最终将实测与计算得到的时序数据整合至数据查看器中，以便于对流量与温度数据进行查询检索，并可视化展示水力发电泄放对下游流量速率的相互作用。