Analysis on the Characteristics of Annual Changes and the Detention Effect of Nitrogen and Phosphorus Nutrients in Plain Reservoirs

¹ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
² Department of Water Ecology and Environment, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
³ Appraisal Center for Environment and Engineering, Ministry of Environmental Protection, Beijing 100012, China

^* Corresponding author: xbliu@iwhr.com

Abstract

In order to study the annual variation characteristics and the retention effect of nitrogen and phosphorus nutrients in plain reservoirs, taking Daheiting Reservoir in North China Plain as an example, the annual variation characteristics of total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH₃-N) and nitrate nitrogen (NO₃-N) in Saheqiao and dam front water of Daheiting Reservoir from January 2018 to December 2018 were analyzed. On this basis, the retention rate of nitrogen and phosphorus and the actual retention rate of Daheiting Reservoir are calculated and analyzed. The results show that the annual average actual retention rate of Daheiting Reservoir in 2018 is only 65.70%, and other indicators are negative. The overall performance of water quality indicators in the year is that the retention effect in wet seasons is greater than that in dry seasons, and the retention effect is affected by the absorption and transformation of algae in the reservoir, the precipitation of particulate nutrients, the release of sediment and the operation and regulation of the reservoir, in which the operation and regulation of the reservoir plays a decisive function. The results show that Daheiting Reservoir has obvious interception effect on TP and still plays the role of “sink”, while it basically maintains the balance of nitrogen.