Assessment of Future Climate Change Impact on Water Quality of Chungju Lake, South Korea, Using WASP Coupled with SWAT

Abstract

This study is to evaluate the future potential impact of climate change on the water quality of Chungju Lake using the Water Quality Analysis Simulation Program (WASP). The lake has a storage capacity of 2.75 Gm3, maximum water surface of 65.7 km2, and forest‐dominant watershed of 6,642 km2. The impact on the lake from the watershed was evaluated by the Soil and Water Assessment Tool (SWAT). The WASP and SWAT were calibrated and validated using the monthly water temperatures from 1998 to 2003, lake water quality data (dissolved oxygen, total nitrogen [T‐N], total phosphorus [T‐P], and chlorophyll‐a [chl‐a]) and daily dam inflow, and monthly stream water quality (sediment, T‐N, and T‐P) data. For the future climate change scenario, the MIROC3.2 HiRes A1B was downscaled for 2020s, 2050s, and 2080s using the Change Factor statistical method. The 2080s temperature and precipitation showed an increase of +4.8°C and +34.4%, respectively, based on a 2000 baseline. For the 2080s watershed T‐N and T‐P loads of up to +87.3 and +19.6%, the 2080s lake T‐N and T‐P concentrations were projected to be 4.00 and 0.030 mg/l from 2.60 and 0.016 mg/l in 2000, respectively. The 2080s chl‐a concentration in the epilimnion and the maximum were 13.97 and 52.45 μg/l compared to 8.64 and 33.48 μg/l in 2000, respectively. The results show that the Chungju Lake will change from its mesotrophic state of 2000 to a eutrophic state by T‐P in the 2020s and by chl‐a in the 2080s. Editor's note: This paper is part of a featured series on Korean Hydrology. The series addresses the need for a new paradigm of river and watershed management for Korea due to climate and land use changes.

Impacts of Climate Change on the Water Quality of a Regulated Prairie River

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How Well Does the Mechanistic Water Quality Model CE‐QUAL‐W2 Represent Biogeochemical Responses to Climatic and Hydrologic Forcing?

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A coupled modeling approach to predict water quality in Lake Taihu, China: linkage to climate change projections

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“…Process-based environmental models driven by data from general circulation models (GCMs) are another approach to explore the response of water quality to future climate (Komatsu et al 2007;Park et al 2013;van Vliet et al 2013). It is useful to investigate changes in a local water system.…”

“…It is useful to investigate changes in a local water system. For example, Park et al (2013) indicated that Chungju Lake (South Korea) would change from a mesotrophic state to a eutrophic state based on total phosphorus (TP) in the 2020s and in the 2080s based on chl a by using GCMs (MIROC3.2 HiRes A1B scenario), SWAT, and WASP. Most studies focus on the impact of air temperature and precipitation changes on water quality rather than a larger suite of meteorological variables (e.g., solar radiation and wind), which are also important drivers.…”