Technical Memorandum Report No. 40
James E.T. Moncur
At present most water planning and forecasting done by the Oahu Board of Water Supply is based on projections of population and per capita water “demand”. It is not population per se, however, which determines demand for water. Rather, price, income, demographic aspects, and the interrelated economic activities underlie the water use patterns of the region’s population. The latter of these attributes is the subject of input-output analysis. A recently completed input-output model for the State of Hawaii is adapted to serve as a water supply planning device. Although proper water use data is not now available for most significant water-using sectors, some rough estimates, borrowings from other states, and a few outright guesses serve to illustrate and interpret the model. An extensive and rather general set of computer programs is a major product of the project. These programs churn out four basic input-output tables–a transactions matrix, a direct requirements matrix, a direct + indirect requirements matrix, and a direct + indirect + induced requirements matrix–given the direct requirements matrix and the final demand levels. Standard income and employment multipliers are produced. Finally, water sector subroutines calculate a gross water use interactions matrix and several measures of direct and of direct + indirect water use coefficients and multipliers.