Analysis Of Response To Climate Change In The Le Sueur River Watershed With Generated Climate Predictions

Abstract

Climate change may have a variety of impacts on Midwest USA agriculture, including impacts to water quality, soil erosion, and nutrient loss. Existing and future climate scenarios were modeled in the Le Sueur watershed using the Soil & Water Assessment Tool (SWAT) to compare the watershed outflow and nutrient concentration outflows under those scenarios. The Le Sueur watershed, in south-central Minnesota, USA, is approximately 1,112 square miles, 87% of which is agriculture. The agriculture land is predominantly in corn and soybean rotations. Much work has been done using global climate models to predict the climate impacts from anthropogenic climate changes, resulting in predictions that the Midwest will experience increased temperatures, increased precipitation in the winter months, and decreased precipitation in the summer months. Minnesota has already documented an increase in extreme rainfall events. These events can cause flooding, damage land and property, and impact agricultural production. This analysis uses six global climate model (GCM) projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for the Le Sueur River watershed area. The magnitude of change of five weather inputs; maximum temperature, minimum temperature, relative humidity, solar radiation, and wind speed, was averaged over three future climate time periods (2006-2029, 2030-2059, and 2060-2099) for two emissions scenarios, RCP 4.5 and 8.5. Average changes were applied to local weather in the Weather Input for Nonpoint Data Simulations (WINDS) model to simulate local climate projections. Predictions from WINDS are used in SWAT, to investigate watershed response to climate change in the Le Sueur River watershed.