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Watershed-Scale Hydrogeologic Analysis and Paleohydrologic Modeling With Applications for Predicting Abandonment of Prehistoric Settlements, Mesa Verde Region, Southwest Colorado. Kenneth E. Kolm and Schaun M. Smith, Washington State University and Colorado School of Mines
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Watershed-Scale Hydrogeologic Analysis and Paleohydrologic Modeling With Applications for Predicting Abandonment of Prehistoric Settlements, Mesa Verde Region, Southwest Colorado Kenneth E. Kolm and Schaun M. Smith, Washington State University and Colorado School of Mines Y. Eugene Yan, Argonne National Laboratory NSF Biocomplexity Conference April 2003
ACKNOWLEDGEMENTSNational Science Foundation Biocomplexity Grant #0119981“Coupled Human/Ecosystems Over Long Periods, Mesa Verde Region Prehispanic Ecodynamics” Dr. Timothy Kohler – PI Dr. Kenneth Kolm - Co-PI Dr. Robert G. Reynolds - Co-PI Dr. Mark Varien - Co-PI
RESEARCHPURPOSE AND OBJECTIVES • Perform hierarchical analysis of environmental system, including watershed-scale hydrogeologic & hydrologic systems. • Develop conceptual and mathematical models of the hydrologic system.
RESEARCHPURPOSE AND OBJECTIVES (cont.) • Model lagged response of water resources to historic and prehistoric (AD 600-1300) climatic changes and environmental stresses. • Develop understanding of impacts to prehistoric settlements by coupling human and hydrologic systems modeling and analysis.
Mesa Top Environment Canyon Rim - K Dakota & Burro Canyon Ss/Water Supply/Gw Discharge Sleeping Ute Tertiary Intrusion Sage/Yellow Jacket Settlement Site Eolian Deposits/Farming/Infiltration/Gw Recharge
Upper Canyon Rim Environment Eolian/Farming/Gw Recharge K Dakota & Burro Canyon SSAquifer Water Supply/Gw Discharge/Springs & Seeps Colluvium J Morrison Units Settlement/Sage Alluvium Pinyon/Juniper Scrub
Lower Canyon Environment Sleeping Ute Tertiary Intrusion J Morrison Units McElmo Creek J Junction Creek Ss J Entrada & Navajo Aquifer Few Settlements Pinyon/Juniper Scrub
TWO BROAD HYPOTHESES • Prehistoric (AD 600-1300) groundwater quantities were controlled by long-term lagged hydro-geologic response, not by direct climate forcing. • This lagged hydrogeologic response to prehistoric climatic changes significantly contributed to depopulation of the Mesa Verde region by reducing the drinking water supply.
SITE-SPECIFIC HYPOTHESES • As the sole variable, climate forcing is not system-limiting. Van West 1994, has shown soil moisture was adequate for sustaining agriculture during prehistoric time periods. • Infiltration functions of eolian deposits are not system limiting. Size of local recharge areas for groundwater subsystems is limiting variable. • Lagged hydrogeologic response is directly related to hydrologic properties of Dakota and Burro Canyon SS. Variability of prehistoric water supply will not match frequency of climatic cycles.
RESEARCH APPROACH 1). Conceptualize and characterize the modern hydrologic system, using integrated, multidisciplinary hierarchical systems analysis. 2). Develop solid and mathematical models to visualize and quantify the modern hydrogeology and hydrologic system on a watershed-scale, and on selected site-specific areas. 3). Test mathematical models by incorporating known hydrologic system stresses which occurred within historic times.
RESEARCH APPROACH (cont.) 4). Develop scenarios of the paleohydrologic system based on paleoclimate records (such as tree ring data) for identifying the relative roles of climate and human-induced stresses. 5). Compare the dynamics of the paleohydrologic system with the cultural activities, population shifts, and abandonment of cultural centers.
BIOCOMPLEXITY LOGIC DIAGRAM FOR CHARACTERIZING ECOSYSTEM Problem Definition: Systems Scale Sustainability Citizen Input Basic Data Gathering and Preparation: Surface, Geomorphic, and Geologic Characterization Atmospheric System Surface Water System and Components Hillsides Channels Lakes and Reservoirs Valley Bottoms and Wetlands Structure and Function Physical Chemical Citizen Involve-ment Ground Water System and Components Unsaturated Zone Saturated Zone Recharge and Discharge Storage and Movement Structure and Function Physical Chemical Geomorphologic System Structure and Function Physical Chemical Biological Terrestrial Ecosystem Aquatic Ecosystem Socioeconomic System Citizen Decisions (after Kolm and Langer, 2000) Decision Support System
Upper Canyon Rim Environment Conceptual Model Climate: Precip/ET Eolian/infiltration/Gw Recharge K Dakota & Burro Canyon SSAquifer Water Supply/Gw Discharge/Springs & Seeps Colluvium Settlement Location Alluvium Pinyon/Juniper Scrub
Hovenweep Canyon and SpringConceptual Model Climate: Precip/ET Mesa Top Infiltration/GwRecharge Gw Discharge/Springs & Seeps Phreatophytes (ET) K Dakota & Burro Canyon Ss Aquifer Gw Flow System
General Hydrogeologic & Hydrologic System Conceptual Model Mesa Top Canyon Rim Lower Canyon
Preliminary 3-D Block Model – Bedrock (w/o Quaternary) K Dakota Aquifer K Mancos Sh J Junction Creek Ss & N Aquifer Tertiary Intrusion J Morrison Units 400 meter resolution
Preliminary 3-D Block Model – Bedrock (w/Quaternary) K Dakota Aquifer Q Eolian Recharge Zone K Mancos Sh J Junction Creek Ss Tertiary Intrusion & N Aquifer J Morrison Units Q Alluvium 400 meter resolution
EXPECTED RESULTS • Hierarchical Systems Analysis of Watersheds - approach transferable to any Colorado Plateau watershed • Couple GMS, Hydrogeologic Solid Block Model, and Mathematical Models - intigration of systems analysis w/3-D hydrogeologic block models, and steady-state modern system models • Paleohydrologic System Mathematical Models - series of transient models as snapshots through prehistoric time using paleoclimate records (tree-ring, paleo-jet streams) • Correlate groundwater models with locations of settlements spatially and temporally
SUMMARY OF PROGRESS TO DATE • Continued analysis of surface, geomorphic, geologic and hydrogeologic data on watershed-scale. • Continued development of 3-dimensional hydrogeologic solid block models (regional and site-specific). • Continued development of modern hydrologic system conceptual models.
SUMMARY OF PROGRESS TO DATE (cont.) • Continued development of modern steady-state mathematical groundwater flow system models. • Conceptualization of prehistoric human settlements placed in landscape based on hydrologic system analysis.
Why Did They Leave? Lowry Settlements
Why Did They Leave? Hovenweep Tower Dakota Aquifer Phreatophytes/Spring
Questions ? Hey, where’s everybody going?