Dynamic land-use/cover improves simulations of long-term watershed-scale streamflow and water quality trends

Details

• Journal Title:
  Journal of Hydrology
• Personal Author:
  Haas, Henrique ; Kalin, Latif ; Tian, Di ; Lehrter, John
• NOAA Program & Office:
  NOS (National Ocean Service) ; NCCOS (National Centers for Coastal Ocean Science)
• Description:
  Long-term trends in water quantity and quality are shaped by climate change (CC) and land-use/cover change (LUC), presenting challenges to food security, ecosystems, and socioeconomic development. Understanding the direction, magnitude, and drivers of these trends is critical for designing effective mitigation and adaptation strategies. While hydrological models are widely used to study streamflow and water quality changes, their ability to capture trend directions and magnitudes remains underexplored. We analyzed long-term trends in streamflow and water quality across the Mobile Bay Watershed (MBW), USA, from 1982 to 2020 using observed streamflow data, CC and LUC observations, and watershed model simulations. Mann-Kendall analysis revealed streamflow declines (59/61 sites) and increasing trends in nitrate (19/29), organic nitrogen (12/19), and organic carbon (10/15), while phosphate, ammonium, and sediment concentrations decreased at most sites. Land-use analysis revealed urbanization (+7%) and decreases in agriculture (–9%) and forests. Annual temperature rose ∼ 0.3 °C/decade, and rainfall by 33 mm/decade. Streamflow declines correlated with increased evapotranspiration (ET) (+1.95 mm/year), likely due to rising temperatures and leaf area index. We applied the Soil and Water Assessment Tool (SWAT) with static (SLU) and dynamic land-use (DLU) scenarios to assess LUC and CC impacts on discharge and water quality loadings. DLU improved streamflow (PBIAS from + 45 % to + 15 %) and nitrate loading (PBIAS from –75 % to –45 %) simulations. The DLU model configuration also better reproduced spatial and temporal water quality trends. Our study demonstrates the value of incorporating dynamic land-use into watershed models for understanding hydrologic change. These findings offer new insights into the capability of watershed models for capturing hydrological and water quality trends amid evolving climate and land-use conditions.
• Source:
  Journal of Hydrology, 661, 133744
• DOI:
  https://doi.org/10.1016/j.jhydrol.2025.133744
• ISSN:
  0022-1694
• Format:
  pdf
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article
• Funding:
  Grant no. NA19NOS4510194
• Rights Information:
  Accepted Manuscript
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:5aa1e4aad7514ed77fed5575e22798521bd65fdb4d96da9c525042f5860245ce30b8b7ca2b5b76f9028ea8f5529412cc34c1cee0411b506008419741898b64f2
• Download URL:
  https://repository.library.noaa.gov/view/noaa/72594/noaa_72594_DS1.pdf
• File Type:
  [PDF - 3.79 MB ]