This paper introduces an intuitive, multicriterion decision making aid utilizing Q-analysis, a technique based in algebraic topology and set theory. This aid ranks twenty-five alternative plans for the water resource management and flood control of the Santa Cruz River Basin. These twenty -five plans have been described in terms of thirteen weighted criteria. Q-analysis is used to investigate a series of binary matrices formed over a range of threshold levels (TLs), indicating different levels at which the plans satisfy the criteria. A computer package performs both Q-analysis and slicing over the TL range. A short discussion concerning additional information that can be drawn from the multicriterion Q-analysis has also been included.

An investigation of salt build -up in two saline discharge lakes was conducted during 1979 in Puerto Peñasco, Mexico. Salt water was discharged to the smaller, deeper Lake I from a shrimp aquaculture prototype at an average rate of 70 liters per second. Water flowed to Lake II through a short channel, and exited the system through either evaporation or infiltration into the underlying sandy soil. In an attempt to differentiate between the evaporation and infiltration terms in the water budget, salt-budget equations have been derived for the two-lake system. These equations have been approximated in a series of monthly time steps, using averages of weekly salinity and water level measurements. Due to imprecision in the data, meaningful results have been obtained only for Lake II. The average calculated infiltration rate is 0.015 meters per day, and calculated evaporation rates show good correspondence with pan evaporation records for a station 2 kilometers away from the lakes. Examination of the salt budget equations shows that, under steady-state conditions, the ultimate salinity is finite. Thus, the maximum expected salinity of a lake may be calculated from worst-case (summertime) values of lake volume, inflow, evaporation, and salinity of incoming water.

Water Yield improvement opportunities were estimated for National Forest lands in Arizona. The land base available for treatment was reduced in a stepwise manner to account for administrative, climatic, and ownership constraints. Research relationships were built upon, and then applied to the remaining land base to project water yield estimates. A continuum of management prescriptions was then displayed to show the range of opportunities. Only the chaparral, ponderosa pine, and mixed conifer types show opportunities of significance. Water yield increases can be realized principally from conversion of chaparral to grass and could add an additional 25 to 70 thousand acre-feet. The ponderosa pine zone could add an additional 15 to 30 thousand acre-feet with intensive management by reducing stocking levels on the commercial National Forest lands. Little opportunity exists within the mixed conifer zone and increases would amount to less than 10 thousand acre -feet. Annual contributions of National Forest lands are likely to range from 40 thousand to 100 thousand acre feet; this will be highly variable depending upon precipitation quantities.