Modala, Naga Raghuveer (2014-12). Assessing the Impacts of Climate Change on Cotton Production in the Texas High Plains and Rolling Plains. Doctoral Dissertation.
Thesis
The Texas Plains, which include the Texas High Plains and Rolling Plains, is one of the largest cotton growing areas in the world. Cotton cultivation in this region is facing severe challenges from rapidly declining groundwater levels and increasing number of droughts. Projected changes in climate are expected to further add to the uncertainty of cotton production in this region. The overall goal of this research was to study the effects of climate change on cotton yield using the CROPGRO-Cotton Cropping System Model (CSM) within the Decision Support System for Agrotechnology Transfer (DSSAT). The future (2041-2070) climate data generated by three Regional Climate Models (RCMs), namely RCM3-GFDL, RCM3-CGCM3 and CRCM-CCSM was obtained from the North American Regional Climate Change Assessment Program (NARCCAP) and was bias corrected using Distribution mapping techniques. The CROPGRO-Cotton model was calibrated, validated and further evaluated using the observed data collected from cotton experiments at Chillicothe in the Texas Rolling Plains during the years 2008 and 2012. A GIS-based distributed modeling approach was used to predict cotton yields across major cotton-growing counties in the Texas Plains under historic and future climate scenarios using the calibrated CROPGRO-Cotton CSM. The RCMs predicted an overall decrease in the average rainfall (30 to 127 mm), increase in the intensity of extreme rainfall events (4% to 14% as per RCM3-GFDL), and increase in both minimum (1.9 to 2.9 oC) and maximum temperatures (2.0 to 3.2 oC) (as per three RCMs) in the future. Deficit irrigation simulations indicated that the maximum seed cotton yields under normal and dry weather conditions could be achieved at 100% and 110% ET replacement scenarios, respectively. The cotton yield at Chillicothe was projected to decrease within a range of 2% to 14.9% under the three RCM future climate scenarios. Majority of the counties in the Texas Plains showed a decline in average cotton yield within a range of 2% to 20% under RCM3-GFDL projected future climate scenario, with the counties in the Texas Rolling Plains being the most affected. A combination of early planting and adoption of no-till practices can minimize the climate change-induced yield losses to some extent.
