Water Supply Allocation Model AL-IV



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Texas Water Development Board


The AL-IV Model described in this document is a computer program that simulates and optimizes the operation of an interconnected system of reservoirs, pump canals, pipelines, and river reaches. AL-IV is an improved version of the previously developed Allocation Model (TWDB, 1972). The major improvement to the previous model (AL-III) consisted of incorporating reservoir evaporation, channel seepage, and consumptive use directly into the Allocation Model as system variables. In past versions of the model, it was required that the water losses from these processes be specified in advance since the solution procedure for the network model did not allow water losses which were flow dependent. The current version of the Allocation Program represents the physical system in a more realistic manner by allowing water losses in impoundments and channels to vary with storage and discharge levels. The improved representation of the physical system was made possible by adapting the Allocation Program to utilize a recently developed network optimization algorithm written by Dr. Paul Jensen and Dr. Gora Bhaumik. Their Network With Gains Algorithm replaced the Out-Of-Kilter Algorithm used in AL-III. The Allocation Model was originally developed by Water Resources Engineers, Inc. under contract to the Texas Water Development Board, with subsequent improvements and modifications made by the staff of the Texas Water Development Board. The current version of the program was adapted from AL-III by Dr. Quentin W. Martin of the Systems Engineering Division of the Texas Water Development Board. The model was developed on the UNIVAC 1108/1106 computer systems but is designed to be essentially machine independent. Core requirements are approximately 41,000 decimals words. Computation time is a function of the size of the problem being analyzed; however, for a two-year network such as the example problem discussed herein, approximately 25 seconds of UNIVAC 1106 execution time is required to obtain a solution. Any inquires concerning the use of this program should be directed to Dr. Quentin W. Martin.


123 pages


water supply, water allocation, water resources, computer model