Analysis of Water Quality Characteristics in Unit Watersheds in the Hangang Basin with Respect to TMDL Implementation

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.

Identification and Apportionment of Potential Pollution Sources Using Multivariate Statistical Techniques and APCS-MLR Model to Assess Surface Water Quality in Imjin River Watershed, South Korea

“…Figure 2 shows the land use ratio and pollutant density ratio for each unit watershed, and that the urban and agricultural areas of IRW accounted for 24.6%. Hantan-A unit watershed had the highest percentage (17.9%) in the use of area, whereas Yeongpyeong-A unit watershed had the highest percentage (29.3%) in the agricultural area [44]. The IRW cannot be used as a drinking water source or tap water because it is impacted by tides twice a day from the estuary of the Han River to the Gorangpo point (approximately 40 km) in Yeoncheon-gun, Gyeonggi Province; hence, water is supplied from Paldang Dam of the Han River [41].…”

“…In terms of the spatial conditions, the IRW showed relatively high levels of BOD, COD, TN, and TP compared to the water quality standards set by the Ministry of Environment in South Korea. The spatial variation in the IRW because of anthropogenic activities and various land use types was evident [44]. The standard deviation was very large for the main streams (IJ-A and IJ-B sites), because they were more affected by summer floods than tributaries were.…”

“…Sites IJ-A and HT-A are located in the upper reaches of the Imjin River and Hantan River, respectively, where there are dense forests and the only basalt in Korea. IJ-B, HT-B, and YP-A sites reflected dilution effects, mainly due to agricultural activities and anthropogenic factors [44]. In cluster 2, sites SC-A and MS-A corresponded to the high-pollution (HP) region; these two sites are located in the Shincheon Stream and Moonsan Stream, respectively.…”

Analyzing Priority Management for Water Quality Improvement Strategies with Regional Characteristics

“…In particular, South Korea began designating NPS pollution management areas in 2007, and by 2023, the number of these areas had increased significantly to 27, and research on the impact of NPS pollution on water quality has been steadily increasing [14]. Given the substantial and increasing contribution to pollution made by NPSs, they have a considerable adverse impact on river water quality in South Korea [15][16][17].…”

Using Multiple Indices for the Water Resource Management of a Monomictic Man-Made Dam in Southern Africa

“…Rapid urbanization and population growth exert water demand pressure. In addition, unsustainable land management practices, poor operation andlack of maintenance of wastewater treatment works (WWTWs) are considered key drivers of water resource quality decline [3][4][5][6]. This is a major concern to water quality authorities as the outcome affects water quality and increases treatment costs, which have direct implications for the economy.…”