Past And Present Hydrogeology Of The Atacama Desert, Northern Chile: Human And Natural System Interactions
This work focuses on the past and present hydrogeology of northern Chile from 19[MASCULINE ORDINAL INDICATOR]S to 23[MASCULINE ORDINAL INDICATOR]S and on the research processes itself. Chapter 2 is a study of the landscape evolution and paleohydrology of the northern portion of the Chilean forearc basin. During the Late Miocene and Early Pliocene, before the forearc basin was deeply incised, a lake existed in the western part of the forearc basin. New 40Ar/39Ar ages of volcanic ashes intercalated with lake and overlying fluvial deposits indicate that lacustrine deposition had begun by 10.86 ± 0.04 Ma, and the final stage of canyon incision occurred after 3.04 ± 0.03 Ma. The existence of a large, deep lake is consistent with, but not conclusive evidence for, a wetter than modern climate in the catchment region during the Late Miocene. Chapter 3 presents an interdisciplinary hydro-economic aquifer model. This single-cell model incorporates groundwater outflows such as flow to rivers, wetlands and springs, that depend on the water table elevation. These outflows are modeled as providing economic, social and environmental benefits. The model is applied to a case history of groundwater extraction in the Ojos de San Pedro region. Chapter 4 is a case study of a cross-disciplinary, intercultural research team that studied a water resource system in northern Chile. Such teams are necessary to solve many complex problems including how to manage scarce water resources. This study focuses on the interaction between cross-disciplinary diversity and cultural diversity during group integration. Results showed that translation served as a facilitator to cross-disciplinary integration of the research team. Cross-disciplinary barriers were found to be more difficult to overcome than intercultural barriers. Chapter 5 presents a steady-state numerical groundwater model developed and calibrated using USGS MODFLOW-2005 based on subsurface geological and hydrological information, stream gauging data, and human water use. This model encompassed the Loa River topographic basin and part of the Altiplano Plateau. Model results indicate that groundwater flow to the region's rivers has likely decreased by ~20% due to human groundwater extraction. Hypothetical lower aquifer pumping scenarios produced reductions in simulated groundwater flow to the rivers and head drawdowns.
Walter,Michael Todd; Allred,Shorna Broussard; Reinfelder,Ying Fan
Ph.D. of Geological Sciences
Doctor of Philosophy
dissertation or thesis