A dynamic optimization model for irrigation investment and management under limited drainage conditions

Irrigation management in a field underlain by a water table aquifer is considered. The water table varies with deep percolation which is in turn a function of the irrigation system and applied water quantities. A drainage system is installed once the water table reaches a maximum height. Optimal irrigation systems and applied water quantities are calculated using dynamic programming. For low confining layer conductivities, deep percolation is progressively reduced through time under optimal management by a combination of improved irrigation systems and reduced water applications. This delays the water table build‐up and postpones drainage costs. Optimal management for a moderately conductive confining layer results in a cyclical policy in which periods of improved irrigation systems and reduced water applications are alternated with periods of traditional irrigation systems and water applications to maintain the water table below the depth requiring drainage system installation.