USE OF SENSITIVITY ANALYSIS TO ESTABLISH RANGES OF SPRING DISCHARGE AND DRINKING WATER SUPPLY FOR PREDICTION OF PREHISTORIC SETTLEMENT POPULATIONS, CANYON OF THE ANCIENTS NATIONAL MONUMENT, SOUTHWEST COLORADO

This study attempts to model for the first time, spring discharge and drinking water supplies related to prehistoric settlement populations in the Canyon of the Ancients National Monument, Colorado. Steady-state and transient ground-water flow models have been developed to simulate the paleohydrologic ground-water resources of the coupled human/natural landscapes from A.D. 600 through 1300. Hydrologic Systems Analysis was used to establish surrogate model parameters due to the lack of engineering data.

A model sensitivity analysis was performed using ranges of recharge, hydraulic conductivity, and specific yield. Parameter sensitivity was used to effectively constrain the model into reasonable end-points. Estimation of the paleohydrologic spring discharge rates were then related to a direct response in prehistoric human settlement patterns as influenced by the viability of drinking water supplies over long periods of time.

Significant results illustrated that constraints of hydrogeologic parameters based initially on analysis of the natural landscape, followed by quantitative model sensitivity analysis, comparatively fell within reasonable ranges. Second, that the variation in parameter ranges directly corresponds to ranges of simulated spring discharge and subsequent prediction of prehistoric Puebloan populations subsisting on landscape from A.D. 600 through 1300.