PALEOHYDROLOGIC MODELING OF THE VIABILITY OF SPRING DISCHARGE FOR PREHISTORIC SETTLEMENTS: A MULTIPLE-SCALE AND MULTI-TEMPORAL HYDROLOGIC SYSTEMS APPROACH, CANYON OF THE ANCIENTS NATIONAL MONUMENT, SOUTHWEST COLORADO

This NSF biocomplexity study attempts for the first time to model the paleohydrology and viability of spring discharge related to prehistoric settlements in the Canyon of the Ancients National Monument, Colorado. Specifically, the intent is to understand and model the lagged response of ground-water resources in the study area to changes in climate and the broad impact of those changes on human occupation. This will be accomplished by understanding and modeling both the modern hydrologic and paleohydrologic systems of the coupled human/natural landscapes from A.D. 600 through 1300.

Multiple-scale, multi-temporal mathematical models simulating the relationships between environmental variables such as frequencies of climatic variations, hydrogeology, and ground-water systems are used to predict paleohydrologic spring discharge. Prediction of the paleohydrologic spring discharge rates are 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.

Results showed that although climate driven, the amount of drinking water available at any given time period corresponds proportionately to the effective extent of the aquifer recharge area. The resulting, delayed ground-water flow response is the direct function of the hydrogeologic characteristics of the aquifer being used by the prehistoric settlements. In most spring locations, some spring flow existed throughout both the wet and dry periods, therefore, suggesting that other cultural variables were also important for depopulating the CANM region.