Linking watershed and receiving water models for eutrophication analysis of Tseng‐Wen Reservoir, Taiwan

Abstract

Eutrophication has been one of the most serious water quality problems for Taiwan's reservoir in recent years. As the water quality of a reservoir is closely related to its watershed development, the fate and transport of pollutants in a watershed is a key consideration to water quality studies in reservoirs. The Tseng‐Wen Reservoir, located in southern Taiwan, features the largest storage volume of impoundments on the island. The watershed of the Tseng‐Wen Reservoir has significant agricultural activities, such as cultivation of tea, mustard, and betel palm. Fertilizer use for these crops in the watershed is very popular, thereby discharging significant nutrient loads into the reservoir. This study uses a watershed model, BASINS, to simulate the flows and nutrient loads from the watershed; BASINS then drives the CE‐QUAL‐W2 model for water quality predictions in the reservoir. The watershed model results are compared with data measured at the Dapu Check Dam, in the main stem of the Tseng‐Wen Creek. Model results show that significant nutrient and sediment loads are generated from the watershed during storms. The verified model was used to simulate the water quality response to various nutrient reduction scenarios. Both watershed and reservoir models offer a very useful tool for water quality management in the Reservoir.

Keywords:

• Eutrophication
• BASINS
• CE‐QUAL‐W2
• Tseng‐Wen Reservoir
• Taiwan