The Long-Term and Retention Impacts of the Intervention Policy for Cage Aquaculture on the Reservoir Water Qualities in Northern China

Abstract

To ensure the safety of the water supply of the Panjiakou reservoir, in 2016, the Chinese central government comprehensively banned the fishing cage culture that had lasted for almost 30 years. However, the long-term effects and retention impacts of the government’s mandatory intervention on the reservoir water quality are unknown. To determine the reservoir water quality, we employed statistical methods along with the mathematical model to investigate the internal relationship since the construction of the reservoir. We applied seasonal trend decomposition using loess (STL) to explore the long-term and seasonality trend of monthly total nitrogen (TN) and total phosphorous (TP). To separate the impact of upstream water quality changes from cage culture on reservoir water quality, we employed generalized additive models (GAMs). We created a model, the LAKE2K model, to investigate the internal sources of the sediment that accumulated during the aquaculture period and its retardant effect. The results revealed that the concentration of upstream TN was more affected by non-point sources than by TP. The long-term policy of encouraging aquaculture has greatly contributed to the increase in the reservoir TP concentration rather than an increase in TN; the prohibition of cage aquaculture has resulted in a sharp drop in TP. After the ban, the sediment became the main source of TP. We suspect that the TP concentration of the reservoir and sediment will decrease gradually until a new equilibrium is reached within 10 years. This study offers lake managers an opportunity to increase their insight into the interaction of management measures with water quality and provides valuable information for the natural recovery of the eutrophic system.

Evolution Characteristics of Water Quality in Plain Reservoirs and Its Relationship with the Economic Development Response: A Case Study of Daheiting Reservoir in Northern China

“…Stage I was from 1992 to 2006. In order to improve the income level of local residents, the government encouraged the development of cage fish culture [22]. At this stage, filter-feeding silver carp and bighead carp, which feed on phytoplankton and zooplankton, were mainly cultured, and no artificial feeding was required.…”

Determination of degradation/reaction rate for surface water quality of recycled water using Lake2K model for large-scale water recycling

“…It is designed to simulate water quality trends in stratified lakes, considering geographic, physical, biochemical, geological, and anthropogenic factors. This one-dimensional mechanistic mass-balance model has been successfully used to simulate water quality and nutrient dynamics in both artificial and natural lakes (Kang et al 2020;Henderson 2019;Mccarthy 2016;Epstein et al 2013;GLEC 2007). A summary of these modeling studies in the literature is given in Table 1.…”