Groundwater as an Ecosystem ResourceGroundwater as an

Ecosystem Resource

Jean M. Bahr

University of Wisconsin - Madison

Jean M. Bahr

University of Wisconsin - Madison

Groundwater as a resource for people

Groundwater also supports a variety of aquatic ecosystems

Figures from USGS Circular 1139

Stream baseflow

Discharge to wetlands

An Environmental Citizens Organizationdedicated to the preservation of Florida's springs

Waterkeepers of Wisconsin (WOW) opposes any taking of spring water or any other ground water reserves that feed

Wisconsin headwaters, lakes, rivers and streams.

Save Our SpringsSave Our Springsof North East Texasof North East Texas

Evidence of increasing public concern

Three Case Studies• Effects of urbanization on springs and

wetlands near Madison WI• Subsurface controls on vegetation patterns in

an “undisturbed” wetland

• Groundwater discharge patterns in a riparian wetland along the lower Wisconsin River

Importance of characterizing hydrostratigraphy Importance of characterizing hydrostratigraphy

Complex flow paths resulting from surface-water groundwater interactions

Complex flow paths resulting from surface-water groundwater interactions

• Susan Swanson • Steve Domber• Laura Parent• Dawn Chapel• Kristin Anderson• Abby Kurz• Jeff Wilcox• Shaili Pfeiffer• Hilary Gittings

Current and Former Students

Geology 729 Classes

EPA WATER & WATERSHEDS

PROJECT TEAMR-82801001-0

Major Springs Near Madison WI

Culver springs (Token Creek)

Nine Springs

Frederick springs (Pheasant Branch)

One of the Nine(+) Springs

Frederick Springs

Outlet from ponds at Culver springs

High Capacity Wells

Circles proportional to pumping

From K. BradburyWI Geol. & Nat. History Survey

Composite cone of depression in the sandstone aquifer

Drawdowns in feet From K. BradburyWI Geol. & Nat. History Survey

Questions and Concerns• How has municipal pumping affected

spring flow and diffuse discharge to wetlands?

• What is the impact of reduced recharge that accompanies suburban development?

• What strategies are available to maintain and restore springs and wetlands in an urbanizing region?

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County-scale groundwater flow model

coarse scale, poor match to measured streamflow

Figure from K. BradburyWI Geol. & Nat. History Survey

Granite

Mt Simon &Eau Claire sandstones

Eau Claireshale

Sandstone& dolomite

BlueMounds

Mt Horeb VeronaMadisonGlacial deposits

sandstone aquifer

water table

citywell

Hydrogeologic Cross Section

Domestic wells

Initial Conceptual Model

From K. BradburyWI Geol. & Nat. History Survey

relativelyundisturbed

wetlands

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Sue Swanson

Three possible sources for spring flow

Glacial Deposits Upper Bedrock

Deep Bedrock

Jan-99 Feb-99 Mar-99 Apr-99 May-99 Jun-99 Jul-99 Aug-99 Sep-99 Oct-99D ate

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cfs

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No site-specific rainfall data

vegetation built up behind weir

immediate response to rainfall due to surface runoff into spring pool

Gaging of streams

and springs

Sediment and watersamples

Bedrock drilling

Straddle packer testing

Borehole flowmeter

logging

spring boils

Preferential flow zonesin shallow bedrock

Results of adding a high permeability layer to the telescoped flow model:

Good match to heads, flows andgroundwater age estimates

Lower Kv neededto match 60 ft headdrop across shale

?

Similar high permeability zones identified near the other majors springs

Conclusions

• Spring location controlled by hydrostratigraphy + paleotopography

• High permeability layer in shallow bedrock necessary to match observed spring and streamflow

Implications for mitigating effects of urbanization

• Limited localized effects of municipal pumping

• Critical to maintain recharge in nearby areas

Vegetation Patterns in Cherokee Marsh

upland

sedgefen

marsh

Abby McDermott Kurz

Study transect consisting of hand augered wells

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1a/1b 1 2 3d/3 4 5 6

Well area

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mb

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ecie

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Vegetation sampling to quantify diversity

Stratigraphy determined from vibracore samples

Four water types based on major ions and other parameters

Interpretation

Strong Discharge

Weaker discharge, some local recharge

Regional discharge blocked by silt loam

Interpretation supported by isotope sampling following summer storms

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Fen Sedge Meadow Marsh

Rain water

Implications

Wetland types in glaciated terrains are influenced by hydrostratigraphy

Subsurface conditions affect water chemistry through controls on discharge and water rock interactions

Attempts to create fens in constructed wetlands may fail if subsurface conditions restrict groundwater discharge

Wetland types in glaciated terrains are influenced by hydrostratigraphy

Subsurface conditions affect water chemistry through controls on discharge and water rock interactions

Attempts to create fens in constructed wetlands may fail if subsurface conditions restrict groundwater discharge

Swamp white oak savannahalong the lower Wisconsin River

Swamp white oak savannahalong the lower Wisconsin River

ShailiPfeiffer

Wis

cons

in R

iver

Sauk City Dam

Cambell Bottoms

InundationFrequency

Nested wells Well and multilevelOnly multilevelStage gauge

Study Site Upper Terrace

Lower Terrace

Lake

Upper Savanna

Lower Savanna

River Bank

River

500 m

Auger Drilling

Miniature Multilevels

Comparison of Major Ion Facies

River

Recentrecharge

25% GW+75% recharge

Bluff GW

Stable Isotopes, June 2000

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2 H

Precipitation (Nine Springs)

Cambell Bottoms Sam ples

meteoricwater line

Stable Isotope Groups

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Distance from Cassell Rd (m)

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vati

on

(m

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LowerTerrace Lower Floodplain

LongLake W I River

Stable Isotope Profile, June 2000

June 2000

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vati

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Calcium

Isotopes

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Distance from Cassell Rd (m)

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230E

leva

tio

n (

m)

Upper Terrace Lower

Terrace Lower Floodplain

LongLake W I River

1 m g/l

26 m g/l

June 2000

Calcium

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Distance from Cassell Rd (m)

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210

215

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230E

leva

tio

n (

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Upper Terrace Lower

Terrace Lower Floodplain

LongLake W I River

1 m g/l

26 m g/l

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vati

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(m

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9.5 m g/l13.1 m g/l

1.7 m g/l

Flooding

Sodium

Conceptual Model asBasis for a Numerical Model

Simulated Flow Paths

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Distance from Cassell Rd (m)

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210

215

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230E

leva

tio

n (

m)

LongLake W I River

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Distance from Cassell Rd (m)

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210

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220

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230E

leva

tio

n (

m)

Upper Terrace Lower

Terrace Lower Floodplain

LongLake W I River

1 m g/l

26 m g/lCalcium

June 2000

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vati

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(m

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1 m g/l

9 m g/l Nitrate-N

Conclusions and Implications Conclusions and Implications

• Changes in flood frequency are dominant cause of degradation

• Temporal variations in groundwater discharge patterns can be tracked with geochemical signatures

• Loss of nitrate during groundwater discharge to riparian wetlands

• Preservation and restoration of riparian wetlands may limit nitrate export to the Mississippi River

• Changes in flood frequency are dominant cause of degradation

• Temporal variations in groundwater discharge patterns can be tracked with geochemical signatures

• Loss of nitrate during groundwater discharge to riparian wetlands

• Preservation and restoration of riparian wetlands may limit nitrate export to the Mississippi River

Some Concluding ObservationsSome Concluding Observations

• Hydrogeologists can and should play an increasing role in projects designed to restore and maintain critical ecosystems

• Interdisciplinary collaboration among physical, biological and social scientists is essential

• Hydrogeologists can and should play an increasing role in projects designed to restore and maintain critical ecosystems

• Interdisciplinary collaboration among physical, biological and social scientists is essential