Climate and land use effects on hydrologic processes in a primarily rain-fed, agricultural watershed

Authors: PHUNG, QUANG - University Of Missouri; THOMPSON, ALLEN - University Of Missouri; Baffaut, Claire; COSTELLO, CHRISTINE - University Of Missouri; Sadler, Edward; SVOMA, BOHUMIL - Salt River Project; LUPO, ANTHONY - University Of Missouri; GAUTAM, SAGAR - University Of Missouri

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2019
Publication Date: 10/9/2019
Citation: Phung, Q., Thompson, A., Baffaut, C., Costello, C., Sadler, E.J., Svoma, B., Lupo, A., Gautam, S. 2019. Climate and land use effects on hydrologic processes in a primarily rain-fed, agricultural watershed. Journal of the American Water Resources Association. 55(5):1196-1215. https://doi.org/10.1111/1752-1688.12764.
DOI: https://doi.org/10.1111/1752-1688.12764

Interpretive Summary: Anticipating changes in water availability and irrigation requirements as a result of both land use and climate change is essential for social and economic decision making. The primary objective of this study was to assess the potential impact of land use and climate change on the processes that control water availability in a primarily rain-fed, agricultural watershed in northeast Missouri, which drains into a water supply reservoir. Global climate, land use and hydrologic simulation models were used to develop near future (2020-2039) and mid-21st century (2040-2059) climate and land use scenarios, and to simulate the resulting effects of these scenarios on infiltration, plant growth, evaporation, and stream flow. Results from 19 climate models showed increased temperatures and annual precipitation, along with a decrease in summer precipitation, a critical factor for crop growth. Higher temperatures were expected to increase evaporation demand from plants and irrigation requirements during the growing season. Results indicated that scheduling of spring field work may be more challenging because of wet soils that make operation of large equipment difficult. Combined climate and land use change scenarios showed distinct seasonal variations in the way stream flow responds to climate and land use changes. Converting crop and pasture land to double forest coverage has the potential to mitigate the effects of climate change on stream flow, thus ensuring future water availability. Scenario analysis informs water resource managers of what may happen during the next 20 -100 years and how they might address the challenges.

Technical Abstract: Anticipating changes in hydrologic variables such as stream flow and base flow are essential for social and economic decision making. The objective of this study was to assess the potential impact of land use and climate change on the hydrological processes of a primarily rain-fed, agriculturally based watershed in northeast Missouri. A detailed evaluation was performed using the Soil and Water Assessment Tool for the near future (2020-2039) and mid-21st century (2040-2059) scenarios. Land use scenarios were created using the Conversion of Land Use and its Effects model. Ensemble results, based on 19 climate models, indicated a temperature increase from 1.0 °C to 2.0 °C in the near and mid-century, respectively. Annual precipitation was projected to increase from 4% to 7%, respectively, along with a decrease in summer precipitation, a critical factor for crop growth. Higher temperatures led to increased potential evapotranspiration and up to 38 mm more irrigation requirements during the growing season. Increased precipitation led to 14% more spring days with soil water content equal or exceeding field capacity in mid-21st century. Combined climate and land use change scenarios showed distinct seasonal variations in hydrological processes. Converting crop and pasture land to double forest coverage has the potential to mitigate the effects of climate change on streamflow, thus ensuring future water availability.