Non-point source pollution control strategy for an off-stream reservoir

Non-point source pollution (NPSP) loads generated from upstream agricultural activities introduces a significant amount of nutrient into a reservoir, thereby accelerating eutrophication, spoiling public water resources, and increasing the cost for water treatment. Adequate control of agricultural non-point source pollution is therefore necessary for improving the water quality. This article describes a series of studies for comparison of three management options for controlling NPSP of the Po-San off-stream reservoir. Some areas in Taiwan do not have an appropriate location to build a general reservoir and have to apply the off-stream method to redirect the stream flow to a reservoir that is not on the stream network. Implementation of a NPSP management strategy for such an off-stream reservoir is more complex than a general one because, in addition to the watershed that drains directly to the reservoir, the drainage areas that drain to the input channel must be properly managed too. Several mathematical and optimization models were developed to evaluate the effectiveness of analyzed control strategies. Data collection, field sampling, model parameter estimation, model verification, and model simulation were implemented for evaluation of strategies based on three major objectives of cost, water quality, and equity. The proposed analyses are intended to improve the comparison and evaluation of NPSP control strategies.