Submitted to: American Meteorological Society
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2002
Publication Date: 10/1/2002
Citation: Zhang, X.C. Assessing impact of interannual climate variations on water resource and crop productivity using CLIGEN and WEPP models. CD-ROM. Proceedings of the 17th Conference on Hydrology. 2003. American Meterological Society.
Interpretive Summary: Models that simulate the movement of water and plant growth are useful tools for assessing the impact of climate variations on water availabilty and crop production. Most models require daily weather input, which can be generated using a climate generation computer program. The objectives of this work were to evaluate the ability of the CLIGEN (a computer program) model to generate various climate scenarios that mimic 'typical' wet, average, and dry year conditions at Chandler, OK and to assess further water availability and crop productivity responses using the Water Erosion Prediction Project (WEPP) model. Ninety-nine years of National Weather Service data of the Chandler station were used in the evaluation. The WEPP model was applied using field data collected from the Water Resources and Erosion watershed at El Reno, OK. Results indicated that CLIGEN was capable of reproducing different climate conditions on the Chandler site. Application of WEPP to different climate conditions showed that winter wheat grain yield increased 0.5 to 0.8% for every 1% increase in average growing-season precipitation on the site, and the rates of the increase were greater under drier initial soil moisture conditions. Results indicated that CLIGEN, when used with response models such as WEPP, provides an effective tool for evaluating crop response to climate variations and for analyzing production risks for any particular cropping system and seasonal climate forecast. This information will be useful to farmers and extension professionals for making informed management decisions.
Technical Abstract: Physically based hydrological and plant growth models are useful tools for assessing the impact of climate variations. Most response models require daily weather, which is often synthesized using stochastic daily weather generators. The objectives were to evaluate the ability of the CLImate GENerator (CLIGEN) model to generate various climate scenarios and to assess further the hydrological and crop productivity responses using the Water Erosion Prediction Project (WEPP) model. Ninety-nine years of National Weather Service data of the Chandler station were used in the evaluation. The WEPP model was calibrated using field data collected from the Water Resource and Erosion watershed at El Reno, OK. Results showed that CLIGEN was capable of preserving statistics of monthly precipitation and reproducing seasonal precipitation patterns for the three year categories on the Chandler site. Predicted percent increase of wheat grain yield per 1% increase of precipitation, which was a function of initial soil moisture storage and total precipitation, ranged from 0.5 to 0.75%. This study demonstrated that CLIGEN, when used in conjunction with response models such as WEPP, could provide a useful tool for assessing the impact of seasonal and interannual climate variations derived from probabilistic type of climate forecast. More importantly, CLIGEN has the potential of downscaling monthly climate forecasts to daily weather series while preserving the statistics of the forecasts.