The management of water resources: a synthesis of goal programming and input-output analysis with application to the Iowa economy

The study focused on the development of a multi-objective model combining input-output analysis and goal programming for providing guidance in the allocation of water resources. The model was applied in the allocation of water between the economic sectors of Iowa and within the eight Iowa water supply areas. The specific objective was to find out whether the state and its eight water supply areas have enough water resources to meet demands of economic and demographic projections to the year 2020;The input-output analysis possesses the capability of capturing the interdependence between the sectors of the economy while the goal programming model provides the analyst an opportunity to isolate certain sectors of the economy as highest priority sectors and to allocate water resources among sectors on the basis of these priorities. The closed system input-output model was utilized in order to capture the induced effects of income on consumption, production, and resource utilization;The eight water supply areas which were considered in the application of the model within the state of Iowa are the Western Southern, Des Moines, Iowa-Cedar, Northeastern, Skunk, Missouri, and Mississippi water supply areas. Four sources of water supply were identified for each area. These sources were alluvial aquifers, other shallow and bedrock aquifers, stream flow, and reservoir storage. Indicators of economic activities in each water supply area were estimated and it was found that the bulk of economic activities are expected to occur in the Des Moines and Iowa-Cedar water supply areas through 2020;Based on projected growth rates of various sectors of the Iowa economy, output projections required to support specified levels of final demands were estimated for the year 2020. These output projections at the state level were scaled down for each water supply area and the model was used to investigate whether each water supply area could accommodate the growth projections under the constraint of its water endowments. Two irrigation scenarios were considered. Irrigation scenario I represented the irrigation of 3.19 million crop acres of irrigable land while scenario II expanded irrigation to over 8 million crop acres of land throughout the state of Iowa;Under irrigation scenario I, the aggregate water consumption in Iowa in the year 2020 is 1.31 trillion gallons, and 1 trillion gallons will be consumed in crop irrigation. Irrigation scenario II consumes 3.12 trillion gallons of water for all economic activities, but the state has enough water resources to supply all consumptive water requirements for all projected economic activities to the year 2020.