Wednesday, 22 May 2002: 1:45 PM
Estimating cotton-Irrigation in georgia using Geostatistics and GIS
Agriculture is the sector that consumes the largest amount of water in Georgia. Due to the continuation of drought conditions, an accurate estimation of agricultural water usage has become necessary in order to design efficient plans for future water use. The Agricultural Water Pumping (www.AgWaterPumping.net) project was initiated in 1999 for the purpose. Approximately 20,000 water withdrawal permits have been issued in Georgia; a statistical sample of 2% of the permits has been selected for monitoring. At these selected sites, monthly readings on water usage for irrigation of different crops are being recorded.
There are 159 counties in Georgia, but irrigation data were only recorded in about 60 counties during the year 2000. This represents only a very small fraction of agricultural land use in each county. The objective of this study was to estimate total irrigation usage for each county in Georgia by applying appropriate geostatistical techniques.
Water usage per acre was computed for different crops from the data collected under the project. Irrigated acreages for different crops for the year 2000 were obtained from the University of Georgia Center for Agribusiness and Economic Development and water usage for the 60 counties was estimated. At present the spatial variation in irrigation usage and techniques to model water usage based on geostatistics are being studied in order to estimate irrigation usage for the remaining counties. We intend to categorize all counties into a few zones depending on the characteristics pertaining to the total water usage. Subsequently the spatial variation in each zone will be modeled using geostatistical techniques, such inverse distance weighting or Kriging. Once an appropriate model is established, the total water usage for irrigation for the entire state of Georgia can be estimated and related to local weather conditions and management practices.
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