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2025 Vol.58, Issue 4 Preview Page

Original research article

Assessing future climate change impacts on hydrological processes in an agricultural watershed using SWAT+
Min-Jin Kim1
,
Won-Ho Nam2*
,
Eun-Mi Hong3
,
Taegon Kim4
,
Seongjoon Kim5
,
Sang-Min Jun6
,
Soon-Kun Choi6
1Graduate Student, School of Social Safety and Systems Engineering, Hankyong National University, Anseong 17579, Korea
2Professor, School of Social Safety and Systems Engineering, Institute of Agricultural Environmental Science, National Agricultural Water Research Center, Hankyong National University, Anseong 17579, Korea
3Associate Professor, School of Natural Resources and Environmental Science, Kangwon National University, Chuncheon 24341, Korea
4Associate Professor, Department of Smart Farm, Jeonbuk National University, Jeonju 54896, Korea
5Professor, Division of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Korea
6Research Scientist, Climate Change Division, National Institute of Agricultural Science, Rural Development Administration, Wanju 55365, Korea
*Corresponding Author
30 November 2025. pp. 549-562
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Abstract

This study assessed the hydrological impacts of future climate change in the Anseongcheon rural watershed using the SWAT+ model and CMIP6-based multi-model ensemble (MME) data. Two Shared Socioeconomic Pathways (SSP), SSP1-2.6 (low-emission) and SSP5-8.5 (high-emission), were analyzed for the near-future (2040 - 2069) and far-future (2070 - 2099) periods. To ensure model reliability, calibration (2018 - 2019) and validation (2020 - 2024) were conducted using observed streamflow data. The average model performance metrics demonstrated satisfactory accuracy, with NSE of 0.62, RSR of 0.64, and PBIAS of -3.05%, supporting the credibility of future projections. Future climate projections from the MME indicate a substantial increase in both precipitation and temperature relative to the historical baseline (1981 - 2010). Under the SSP5-8.5 far-future scenario, precipitation is projected to increase by 28.4%, and mean temperature to rise by 5.8°C. Analysis of hydrological components reveals pronounced seasonal variability, particularly under the high-emission scenario. Surface runoff is projected to decrease sharply in spring (-41.07%) and winter (-35.15%), whereas a significant rise in summer precipitation (up to +24.4%) leads to increased surface runoff (+25.89%) and lateral flow (+3.39%). Moreover, strong winter warming results in a remarkable 149.0% increase in evapotranspiration, driven by elevated temperatures despite potential reductions in winter precipitation. Overall, the findings highlight intensified seasonal fluctuations in hydrological processes within rural watersheds under high-emission conditions and demonstrate the robustness of SWAT+ as a tool for supporting adaptive water management strategies in a changing climate.

Hydrological responses (SSP1-2.6, SSP5-8.5) were assessed. Under SSP5-8.5 far future, runoff rose +25.9% (summer) and evapotranspiration +149% (winter).
Scenarios Variable Period Spring Summer Autumn Winter
SSP1-2.6 Surface runoff (mm) NF1 11.44 114.51 38.72 1.35
FF2 10.82 124.26 37.71 1.67
Change (%) -5.42 8.51 -2.61 23.70
Lateral flow (mm) NF1 5.87 11.78 10.82 2.13
FF2 5.26 11.66 10.97 2.22
Change (%) -10.39 -1.02 1.39 4.23
Evapotranspiration (mm) NF1 230.5 415.92 149.34 19.74
FF2 247.36 417.51 160.77 19.99
Change (%) 7.31 0.38 7.65 1.27
SSP5-8.5 Surface runoff (mm) NF1 8.01 115.49 53.27 1.65
FF2 4.72 145.39 66.21 1.07
Change (%) -41.07 25.89 24.29 -35.15
Lateral flow (mm) NF1 5.03 11.51 11.14 2.75
FF2 2.41 11.9 11.55 2.47
Change (%) -52.09 3.39 3.68 -10.18
Evapotranspiration (mm) NF1 248.13 418.7 144.96 30.59
FF2 304.61 431.27 176.77 76.17
Change (%) 22.76 3.00 21.94 149.00

1NF: Near future (2040 - 2069);

2FF: Far future (2070 - 2099).

Keywords
Agricultural watershed
Climate change
Hydrologic response
SSP scenarios
SWAT+
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Information
  • Publisher :Korean Society of Soil Science and Fertilizer
  • Publisher(Ko) :한국토양비료학회
  • Journal Title :Korean Journal of Soil Science and Fertilizer
  • Journal Title(Ko) :한국토양비료학회 학회지
  • Volume : 58
  • No :4
  • Pages :549-562
  • Received Date : 2025-10-02
  • Revised Date : 2025-10-25
  • Accepted Date : 2025-10-27
  • DOI :https://doi.org/10.7745/KJSSF.2025.58.4.549
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