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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATION OF CLIMATE VARIABILITY AND FORECASTS INTO RISK-BASED MANAGEMENT TOOLS FOR AGRICULTURE PRODUCTION AND RESOURCE CONSERVATION Title: Simulating Regional Impacts of Climate Change on Water Resource, Erosion, and Wheat Production Using Cligen and Wepp Models.

Author
item Zhang, Xunchang

Submitted to: World Resource Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2005
Publication Date: August 15, 2005
Citation: Zhang, X.J. 2005. Simulating regional impacts of climate change on water resource, erosion, and wheat production using cligen and wepp models. World Resource Review. 17(3):335-349.

Interpretive Summary: Knowledge of potential impacts of climate changes on natural resources is critical to conservation planning. The goal of this study was to simulate the regional impacts of climate change on water resources, soil erosion, and wheat production in central Oklahoma using the Water Erosion Prediction Project (WEPP) computer model and a weather generation program (CLIGEN). Climate changes, projected for 2070-2099 using the U.K. Hadley Centre’s computer climate model (HadCM3) under the high (A2a), low (B2a), and intermediate (GGa1) CO2 emissions scenarios, were used. The WEPP model was run for each climate scenario in three tillage systems. The HadCM3 model predicted a general decline in annual precipitation in the region over the century. As a result of precipitation reduction, predicted plant evaporation, soil evaporation, and the long-term soil water reserve were reduced in all three climate change scenarios. However, the decreases in rainfall did not necessarily result in reductions in wheat yields, largely because most precipitation decreases were predicted in the non-growing season. About a 1% decrease in wheat yields was predicted for scenarios A2a and B2a, while a 6% increase was predicted for GGa1 scenario. Regarding soil erosion, the results indicated a possibility of increased erosion despite the predicted decrease in annual precipitation due to the predicted increases in precipitation daily intensity. However, simulated results suggest the no-till system is sufficient to maintain low erosion levels in the region.

Technical Abstract: Climate change can affect agricultural production and soil and water conservation. The objective of this study was to simulate the first order sensitivity of water resources, soil erosion, and wheat production to assumed climate changes in the region near El Reno, Oklahoma using the Water Erosion Prediction Project (WEPP) model and a climate generator (CLIGEN). Monthly forecasts for the periods of 1950-1999 and 2070-2099 for the region, projected by the U.K. Hadley Centre’s third generation general circulation model (HadCM3), were used. Three emissions scenarios (A2a, B2a, and GGa1) were selected. The WEPP model was run for each scenario in three tillage systems. Projected changes in monthly mean and variance between the two periods at the HadCM3 grid scale were downscaled to daily climate data using CLIGEN. Spatial downscaling from the HadCM3 grid scale to the target location was not intended, and therefore the responses reported in this paper reflect a first-order regional sensitivity. The HadCM3 predicted a general decrease in precipitation in the study area over the century. As a result of precipitation reduction, predicted plant evaporation, soil evaporation, and the long-term soil water reserve were reduced in all three climate change scenarios. However, the decreases in rainfall did not necessarily result in reductions in wheat yields, largely because most decreases were predicted in the non-growing season. About a 1% decrease in wheat yields were predicted for A2a and B2a, while a 6 % increase was predicted for GGa1. Regarding soil erosion, the results indicate a possibility for increasing erosion despite the predicted decreases in annual precipitation due to the predicted increases in annual precipitation variability. This is especially true for GGa1, in which soil loss was predicted to increase about 20 to 50%. However, simulated results suggest the no-till system is sufficient to maintain low erosion levels in the regions and thus protect the soil and ecosystem under the assumed climate changes.

Last Modified: 10/24/2014
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