Crustal Geophysics and Geochemistry Science Center

Handcart Gulch — Integrated Headwaters Research on Hydrogeologic and Geochemical Processes and Monitoring of Environmental Change

Research Overview

Numerous alpine watersheds in the intermountain west are found in geologically complex settings characterized by a number of water quantity and quality issues. These high altitude areas are critical headwater regions at the top of the hydrologic cycle where groundwater is recharged, ecosystems are sustained, and sensitivity to climate change is high, particularly for the mid-latitudes. The overarching research goal is to better understand hydrogeological processes and to measure and monitor environmental change. One of several unique aspects of Handcart Gulch is that there are numerous groundwater wells, one at the Continental Divide, used to measure time-series water level and temperature data. This website describes completed, current, and proposed future research in headwaters regions of the southern Rocky Mountains. Research in Handcart Gulch started in 2003 and has been supported by the U.S. Geological Survey, Mineral Resources, National Cooperative Geologic Mapping, Toxics Substances Hydrology, and Mendenhall Postdoctoral Fellowship Programs. Four deep boreholes were originally donated to the U.S. Geological Survey and then supplemented with nine additional holes. The research described here has been done in cooperation with the U.S. Forest Service, the Colorado Geological Survey, and the University of Colorado, Boulder.

Figure 1. Diagram of mountain flow hydrologic system - click on image for large version.

Figure 1: Illustration of typical mountainous terrain, showing components of the hydrologic cycle as it pertains to the occurrence, storage, and flow of mountain surface and groundwaters. Precipitation that falls within the watershed divides (PPTin) is included in water-budget calculations for individual watersheds. Total stream flow (TSF) to the mouth (TSFmouth) of the main stream is composed of baseflow (BF) and overland flow (OF). Water leaves the watershed primarily by evapotranspiration (ET) and groundwater outflow (GO). Groundwater flow occurs parallel to the cross-section and out of the watershed, and also down gradient, toward the reader. The water table (WT) largely mimics topography, and smooth groundwater flow lines illustrate continuous flow, whereas jagged lines illustrate tortuous flow controlled by discrete features, such as fractures and faults. An active flow zone is indicated where most groundwater is locally driven by extreme to high, mountainous hydraulic gradients, over human time scales. Flow that may be driven regionally, over geologic time scales, possibly recharging the Earth's upper crust, is also illustrated. [Click on image for large version.]

Figure 2. Handcart Gulch Geology - click on image for large version

Figure 2: Simplified geologic map (modified from Lovering, 1935), block diagram, and cross section of the Handcart Gulch study area draped on a digital elevation model showing the location of the research wells. Also shown is a geological conceptual model in cross section depicting the major features that might control the ground-water flow system and associated contaminant sources. [Click on image for large version.]

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