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Georgia Water Resources Conference

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Author: Guerra, Larry C. × Author: Hook, James E. × Start date: 2000 × Item Type: Publication × Type: Text ×

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Now showing 1 - 4 of 4
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    Impact of local weather variability on irrigation water use in Georgia
    (Georgia Institute of Technology, 2005-04) Guerra, Larry C. ; Garcia y Garcia, Axel ; Hoogenboom, Gerrit ; Hook, James E. ; Harrison, Kerry A. ; Boken, Vijendra K.
    Irrigation is often used to offset the impact of rainfall variability on crop yield and to reduce the risk associated with weather variability. However, especially for the state of Georgia, how much water is required and how much water is actually being used for irrigation is largely unknown. The objective of this study was to determine the relationship between farmers' irrigation applications, crop types, and local weather conditions. Farmers' monthly irrigation applications for three major crops in Georgia, i.e., cotton, peanut and maize, were obtained from selected sites of the Agricultural Water Pumping program. Significant relationships between monthly irrigation depth and monthly water deficit were obtained for only two of seven months for cotton, five of seven months for peanut, and only one of six months for maize. Individual differences among farmers on how much water they applied contributed to the lack of correlation between monthly irrigation depth and monthly water deficit. Future efforts should focus on a better understanding of the factors that contribute to the farmer's decisions related to when to irrigate and how much water to apply.
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    The potential of a decision support system to simulate irrigation scheduling in southwest Georgia
    (Georgia Institute of Technology, 2005-04) Garcia y Garcia, Axel ; Guerra, Larry C. ; Hoogenboom, Gerrit ; Hook, James E. ; Harrison, Kerry A.
    A decision support system was used to simulate irrigation scheduling for maize, cotton, and peanut for the 2001 to 2004 cropping seasons in southwest Georgia. The results were compared with observed data from the Agricultural Water Pumping (AWP) project. The comparison of the cumulative distribution functions between simulated and observed monthly amounts of irrigation showed significant differences for the three crops. However, almost 50% of the simulated cotton and peanut monthly amounts of irrigation were adequately correlated with the observed data. The analysis and comparison of the observed and simulated irrigation scheduling showed the potential that the Decision Support System for Agrotechnology Transfer (DSSAT) crop simulation models can be used as a tool for on-farm irrigation scheduling.
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    Water Use Estimation for Some Major Crops in Georgia Using Geospatial Modeling
    (Georgia Institute of Technology, 2003-04) Boken, Vijendra K. ; Hoogenboom, Gerrit ; Guerra, Larry C. ; Hook, James E. ; Thomas, Daniel L. ; Harrison, Kerry A.
    Agricultural water use estimation can contribute to finding a satisfactory solution of the water dispute among the states of Alabama, Florida, and Georgia. In this paper, the depths of irrigation for cotton, peanut, corn, and soybean are estimated for the Flint, Central, and Coastal water zones of Georgia for 2000, 2001, and 2002. In addition, the volume of irrigation for these crops are estimated for 2000 and 2001. The estimation was based on the spatial interpolation of the data collected under the Agricultural Water Pumping project. The interpolation techniques included the inverse distance weighting, local polynomial, global polynomial, radial basis function, ordinary kriging, and universal kriging. The total volume of irrigation was highest for the Flint zone (578.4 Mm3 ), followed by the Central zone (296.3 Mm3 ) and the Coastal zone (103.0 Mm3 ) for 2000. For 2001, the irrigation volume declined by 41% for the Flint zone, 31% for the Central zone, and 20% for the Coastal zone.
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    Estimating Statewide Irrigation Requirements Using a Crop Simulation Model
    (Georgia Institute of Technology, 2003-04) Guerra, Larry C. ; Hoogenboom, Gerrit ; Boken, Vijendra K. ; Thomas, Daniel L. ; Hook, James E. ; Harrison, Kerry A.
    An understanding of water needs in agriculture is a critical input in resolving the water resource issues that confront the state of Georgia. Unfortunately, how much water is required and how much water is actually being used for irrigation is unknown. The objective of this study was to estimate water demand for irrigation for the entire state of Georgia using a crop simulation model. The irrigation requirements for all the counties where irrigated cotton, corn, peanut and soybean were grown in 2000, 2001 and 2002 were estimated using the Environmental Policy Integrated Climate (EPIC) model. These counties were distributed across seven regions; with three regions, i.e., Flint Basin, Central Coastal Plain and Coastal Zone, representing the major growing areas. The combined irrigation withdrawal in the Flint Basin, Central Coastal Plain and Coastal Zone accounted for about 98% and 99% of the statewide total irrigation withdrawal in 2000 and 2001, respectively, mainly due to large irrigated acreage in those regions. Statewide total irrigation withdrawal was estimated to be 199,125 Mgallons in 2000 and 114,101 Mgallons in 2001. These irrigation requirements will vary from year to year depending on the spatial and temporal distribution of rainfall during the growing season. Total irrigated acreage also had a major impact on irrigation withdrawal. We will implement the model for other crops to determine the total irrigation withdrawals for agriculture in the state of Georgia.