Integrated decision making for reservoir, irrigation, and crop management

An integrated approach to reservoir, irrigation, min cropping management wh ich links four different models-a hydrologic model (PRMS), a crop growth si mulation model (EPIC), an economic model based on linear programming, and a dynamic programming model-is developed and demonstrated. The demonstration is based on an irrigation district located in a subhumid climate with an i rrigation reservoir large enough for over-year storage. The model is used t o make repeated simulations for various planning horizons. Two different ty pes of results are presented. The first provides rite probability that each of the various farm plans (land/crop/water allocation) will be chosen as t he optimum in the first year of the planning horizon. The second approach p rovides probability distributions of accumulated revenues over a chosen len gth of planning horizon. Each distribution is associated with an initial re servoir level and a particular farm plan in the first year of the planning horizon. The consequence of selecting certain farm plans at the beginning o f a specified planning horizon is therefore quantified in a probabilistic w ay. Based on families of probability-revenue curves, an irrigation manager can simultaneously evaluate crop, irrigation, and reservoir management opti ons. (C) 1998 Elsevier Science Ltd. All rights reserved.