You are here:
WATERSHED BOUNDARY CONDITIONS FOR GLOBAL CHANGE IMPACT ANALYSIS
Citation:
Schade*, T G. AND M. Hanfler. WATERSHED BOUNDARY CONDITIONS FOR GLOBAL CHANGE IMPACT ANALYSIS. Presented at ASCE/EWRI World Water and Environmental Resources Congress 2003, Philadelphia, PA, June 23 - 26, 2003.
Impact/Purpose:
To inform the public
Description:
The US Global Change Research Program (USGCRP) studies (among other issues) the impact of global change on water quality. This field study evaluates the impact of global changes (land-use change and climate change) on source water quality. Changes in source water quality change the cost of drinking water treatment. Obvious changes to the upstream environment such as land development or natural resource production effect source water quality. Other changes that happen at a global scale, such as atmospheric warming or drought frequency alter the hydrologic cycle through atmospheric or groundwater processes which, in turn, may impact source water quality.
Using data from two carefully selected watershed sites, this study weighs the relative merit of land-use practices as a means to mitigate impact to source water from the large-scale atmospheric changes. This paper will present a unique framework for the site selection process. The goal of this process was to find sites for which we could define a "boundary" condition. "Boundary" in our context means more than the areal extent of the watershed; we need to define the boundary of the model state for some set of hydrologic parameters in time and space.
The site selection process proceeded in two phases. The goal of the first phase was to find several watersheds that have long-term historical flow data. Because the data that we collect will only include time from the present forward, these larger watersheds provide the nesting that we will need to simulate or extrapolate results back in time. In the first phase, we looked at USGS streamflow data for all of the monitored points in the Ohio River Basin. From this set of points we set a series of criteria for the sites including: period of record, size of tributary area, etc. This data is available from the USGS, and it is basically an office exercise.
For the second phase of the site selection task, we selected the most appropriate USGS sites based on the physical properties that we had from remote sensing, topographic maps and geologic studies. We went into the field to investigate each of these large watersheds looking for 40- to 200-acre study sites where the land will be developed soon. We selected two study sites that meet all of our criteria, one in Greenville, PA and one in Marysville, OH.
Preliminary data from these sites will be presented in the context of source water protection for the drinking water supply of Pittsburgh, PA and for Columbus, OH.