Groundwater Withdrawals Needed to Meet Irrigation Demands During Drought Years.
Knowledge of water demands during periods of severe drought is needed to develop strategies for water management. Drought becomes hydrologically significant, lowering groundwater levels, after six or more months of below average rainfall. However, shorter drought periods can result in sharply increased water demands if crops begin to suffer on irrigated land. Agricultural development and water needs in south Georgia will grow as fruit and vegetable production shifts from highly populated southern Florida and water deficient California. At present, Georgia has little control of irrigation water withdrawals from wells installed before 1989. However, future growth and development in the state, may make regional water management necessary. Recent droughts in the Southeast have increased awareness of limited water supplies in a region commonly considered to have abundant rainfall and inexhaustible groundwater reserves. For the first time, wells used for irrigation must be permitted in Georgia, and pumping records must be maintained. As water resource planners struggle with methods to anticipate future water use patterns, they have little historical records upon which they can draw. Yet, water withdrawals for irrigation make up the greatest total water use in the Coastal Plain region of Georgia. An inexpensive method is needed for estimating irrigation water needs, particularly for drought periods when competition and demands for water are greatest. This study was undertaken to provide Georgia water use planners with realistic estimates of amount and timing of irrigation withdrawals which could be expected during those years when competition for water is the greatest.