Abstract
Spatiotemporal water quality tendencies before and after total maximum daily load (TMDL) implementation in the Hangang basin were analyzed to determine the water quality improvement resulting from the TMDL policy. The periodicities of water quality indicators were also analyzed and water quality characteristics corresponding to different unit watershed units were identified in terms of pollution source. Considering five water quality indicators, including biochemical oxygen demand and total phosphorus, it was observed that water quality indicator concentrations were low in the upstream areas of the Bukhangang and Namhangang watersheds. However, they were high between the downstream areas of the Namhangang watershed and the Imjingang watershed and in the Hangang downstream and Jinwicheon watersheds. Additionally, the concentrations of water quality indicators in most of the unit watersheds where TMDL had been implemented decreased after TMDL implementation. However, increasing tendencies in the concentrations of water quality indicators continued to be observed in some of the watershed units in the upstream areas of the Bukhangang and Namhangang watersheds, possibly because these watersheds are affected by nonpoint source pollution owing to rainfall. Therefore, in the future, it would be necessary to implement policies that take these findings into consideration.
Highlights
In South Korea, there has been deterioration in river water quality over the last 30 years owing to increased discharge of wastewater resulting from population growth, rapid industrialization, and rapid urbanization [1]
In this study, performed the and spatiotemporal water quality tendencies before and after total maximum daily load (TMDL) implementation to clarify the effects of the TMDL policy on the unit watersheds in the Hangang basin, which serves as an important drinking water source in South Korea
We performed the spatiotemporal analysis of water quality tendencies before and after TMDL implementation to clarify the effects of the TMDL policy on the unit watersheds in the Hangang basin, which serves as an important drinking water source in South Korea
Summary
In South Korea, there has been deterioration in river water quality over the last 30 years owing to increased discharge of wastewater resulting from population growth, rapid industrialization, and rapid urbanization [1]. To address this problem, pollutant concentrations have been regulated by implementing emission limits; the water quality criteria specified by these emission limits are being exceeded, indicating that water quality management systems that are based on pollutant concentration regulation are limited. Thereafter, the target water quality is set considering the watershed at the end of the unit, as well as the current water quality, level of development, and the reduction capacity of the unit
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