HYDROLOGIC SYSTEMS-BASED GROUNDWATER MODELING FOR DETERMINING SUSTAINABILITY OF DRINKING WATER SUPPLIES IN ANCIENT COMMUNITIES

Research is currently on-going which attempts to understand the relationship between prehistoric settlement populations and their drinking water supplies, predominantly spring discharge, in the Canyon of the Ancients National Monument, Colorado. Steady-state and transient ground-water flow models have been developed to simulate paleohydrologic ground-water resources of the coupled human/natural landscapes in the 7th through 13th centuries. The purpose this paper is to present the methodology developed, and to compare simulated drinking water supplies with ancient Puebloan population distributions of three archaeologically significant villages.

Hydrologic Systems Analysis was used to establish surrogate model parameters due to the lack of spatial and temporal engineering data. Model sensitivity analysis was performed using ranges of values for recharge, hydraulic conductivity, and specific yield to effectively constrain mathematical model inputs. Statistical error analysis was applied to reduce surrogate parameter value uncertainty. Graphical correlations of the simulated spring discharge rate curves were compared to the prehistoric human populations spatially and temporally on the landscape. These geoarchaeological data were then used to determine the sustainability of drinking water supplies in ancient communities from A.D. 600 through A.D. 1300.

Results relating sustainability of drinking water supplies to ancient Puebloan population distribution are compared for three archaeological sites including Sand Canyon Pueblo Ruin, Yellow Jacket Pueblo Ruin, and Lowry Pueblo Ruin. Hydrologic Systems-based groundwater modeling in conjunction with sensitivity and statistical error analysis proved significant in reducing uncertainty in these comparisons and in adding validity to conclusions.