Regional Evaluation of Ground-water and Surface Water Interactions: Preliminary Method Development and Analysis

Berg, Richard C.; Keefer, Donald A.; Demissie, Misganaw; Ramamurthy, Ganapathi

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Description

Title

Regional Evaluation of Ground-water and Surface Water Interactions: Preliminary Method Development and Analysis

Author(s)

• Berg, Richard C.
• Keefer, Donald A.
• Demissie, Misganaw
• Ramamurthy, Ganapathi

Issue Date

1997

Keyword(s)

• ground-water
• surface water
• stream discharges

Abstract

• A methodology has been developed for classifying ground-water and surface water interactions using a combination of small-scale map data (1:250,000) and existing data on stream discharges. Information from statewide maps of soils, geologic materials, and land surface topography was combined and used to define unique hydrogeologic settings, or terranes. A new map was developed that includes 11 different hydrogeologic terranes. Separately, a statewide map of watershed boundaries (developed from 1:24,000 data) was overlaid with a map and database of U.S. Geological Survey stream gaging stations. Low-flow data (area-normalized Q90 values) from the gaging station database were used to identify four different Q90 groupings. A modified watershed map was developed by reclassifying the statewide watershed map according to these new Q90 groups, resulting in a low-flow map with more than 200 watersheds. The hydrogeologic terrane map was then combined with the modified watershed map, and a preliminary analysis was conducted of the combined data. This analysis indicates that, in general, low-flow rates in the defined watersheds are most closely related to soil hydraulic characteristics and less closely related to the presence of an aquifer within 50 feet of the land surface, the landscape position, or the slope of the land surface. Although these observations may be considered obvious, to our knowledge such observations have never been made on the basis of statewide data nor with the data sets used for this study. This research suggests that our general approach can be valuable for defining functional relationships between hydrogeologic settings and streamflow characteristics. Moreover, several areas of additional research were identified during the data analysis that could enhance the utility of this approach in future efforts.
• A methodology has been developed for classifying ground-water and surface water interactions using a combination of small-scale map data (1:250,000) and existing data on stream discharges. Information from statewide maps of soils, geologic materials, and land surface topography was combined and used to define unique hydrogeologic settings, or terranes. A new map was developed that includes 11 different hydrogeologic terranes. Separately, a statewide map of watershed boundaries (developed from 1:24,000 data) was overlaid with a map and database of U.S. Geological Survey stream gaging stations. Low-flow data (area-normalized Q90 values) from the gaging station database were used to identify four different Q90 groupings. A modified watershed map was developed by reclassifying the statewide watershed map according to these new Q90 groups, resulting in a low-flow map with more than 200 watersheds. The hydrogeologic terrane map was then combined with the modified watershed map, and a preliminary analysis was conducted of the combined data. This analysis indicates that, in general, low-flow rates in the defined watersheds are most closely related to soil hydraulic characteristics and less closely related to the presence of an aquifer within 50 feet of the land surface, the landscape position, or the slope of the land surface. Although these observations may be considered obvious, to our knowledge such observations have never been made on the basis of statewide data nor with the data sets used for this study. This research suggests that our general approach can be valuable for defining functional relationships between hydrogeologic settings and streamflow characteristics. Moreover, several areas of additional research were identified during the data analysis that could enhance the utility of this approach in future efforts.

Publisher

Illinois State Water Survey

Series/Report Name or Number

ISWS Miscellaneous Publication MP-181

Type of Resource

text

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http://hdl.handle.net/2142/49877

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