Integrated Decision Making for Reservoir, Irrigation, and Crop Management

An integrated approach to reservoir, irrigation, and cropping management which links four di€erent modelsÐa hydrologic model (PRMS), a crop growth simulation model (EPIC), an economic model based on linear programming, and a dynamic programming modelÐis developed and demonstrated. The demonstration is based on an irrigation district located in a subhumid climate with an irrigation reservoir large enough for over-year storage. The model is used to make repeated simulations for various planning horizons. Two di€erent types of results are presented. The ®rst provides the probability that each of the various farm plans (land/crop/water allocation) will be chosen as the optimum in the ®rst year of the planning horizon. The second approach provides probability distributions of accumulated revenues over a chosen length of planning horizon. Each distribution is associated with an initial reservoir level and a particular farm plan in the ®rst year of the planning horizon. The consequence of selecting certain farm plans at the beginning of a speci®ed planning horizon is therefore quanti®ed in a probabilistic way. Based on families of probability±revenue curves, an irrigation manager can simultaneously evaluate crop, irrigation, and reservoir management options. # 1998 Elsevier Science Ltd. All rights reserved Agricultural Systems, Vol. 58, No. 4, pp. 529±554, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain P I I : S 0 3 0 8 5 2 1 X ( 9 8 ) 0 0 0 6 8 7 0308-521X/98 $Ðsee front matter 529 *Towhomcorrespondence should be addressed. Tel.:+1-405-744-8423; fax:+1-405-744-6059; e-mail: [email protected]