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Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

Hydrological Processes

By:
, , , and
DOI: 10.1002/hyp.5953

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Abstract

18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times
Series title:
Hydrological Processes
DOI:
10.1002/hyp.5953
Volume
20
Issue:
8
Year Published:
2006
Language:
English
Publisher:
Wiley
Description:
20 p.
First page:
1753
Last page:
1772
Country:
United States
State:
Minnesota
Other Geospatial:
Shingobee River Headwaters Area
Online Only (Y/N):
N
Additional Online Files(Y/N):
N