Analytical Model for Management of Alluvial Aquifers

Under the doctrine of prior appropriation, the recent inclusion of wells in the existing priority system of water rights in Colorado has created new problems for water management in tributary alluvial aquifers. Irrigation and municipal wells, being generally junior to surface water rights on a river, are subject to complete shut down if they cannot compensate for the river depletion due to pumping. Plans of augmentation have been encouraged and accepted by the Division of Water Resources. Under these plans the well owners must provide for the river depletion in both time and space either by recharge operations or by direct deliveries to the river from acquired surface water. In order to evaluate these plans of augmentation, an analytical approach has been used to estimate the change in storage of the ground water and the rate and amount of movement of water to and from the river. Computer programs have been developed which will estimate these effects individually for any combination of well pumping and recharge operations through canals, ditches, reservoirs, and wells.