1 / 47

Groundwater as an Ecosystem Resource

Groundwater as an Ecosystem Resource. Jean M. Bahr University of Wisconsin - Madison. Groundwater as a resource for people. Groundwater also supports a variety of aquatic ecosystems. Stream baseflow. Discharge to wetlands. Figures from USGS Circular 1139.

sammy
Download Presentation

Groundwater as an Ecosystem Resource

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Groundwater as an Ecosystem Resource Jean M. Bahr University of Wisconsin - Madison

  2. Groundwater as a resource for people

  3. Groundwater also supports a variety of aquatic ecosystems Stream baseflow Discharge to wetlands Figures from USGS Circular 1139

  4. An Environmental Citizens Organizationdedicated to the preservation of Florida's springs Evidence of increasing public concern Waterkeepers of Wisconsin (WOW) opposes any taking of spring wateror any other ground water reserves that feedWisconsin headwaters, lakes, rivers and streams. Save Our Springs of North East Texas

  5. 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 Complex flow paths resulting from surface-water groundwater interactions

  6. Current and Former Students • Susan Swanson • Steve Domber • Laura Parent • Dawn Chapel • Kristin Anderson • Abby Kurz • Jeff Wilcox • Shaili Pfeiffer • Hilary Gittings Geology 729 Classes

  7. EPA WATER & WATERSHEDS PROJECT TEAM R-82801001-0

  8. Major Springs Near Madison WI Frederick springs (Pheasant Branch) Culver springs (Token Creek) Nine Springs

  9. One of the Nine(+) Springs Frederick Springs Outlet from ponds at Culver springs

  10. High Capacity Wells Circles proportional to pumping From K. Bradbury WI Geol. & Nat. History Survey

  11. Composite cone of depression in the sandstone aquifer Drawdowns in feet From K. Bradbury WI Geol. & Nat. History Survey

  12. 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?

  13. County-scale groundwater flow model coarse scale, poor match to measured streamflow Figure from K. Bradbury WI Geol. & Nat. History Survey

  14. Initial Conceptual Model Domestic wells From K. Bradbury WI Geol. & Nat. History Survey

  15. relatively undisturbed wetlands Sue Swanson

  16. Three possible sources for spring flow Glacial Deposits Upper Bedrock Deep Bedrock

  17. Sediment and water samples Gaging of streams and springs

  18. Bedrock drilling Straddle packer testing Borehole flowmeter logging

  19. Preferential flow zones in shallow bedrock spring boils

  20. Lower Kv needed to match 60 ft head drop across shale Results of adding a high permeability layer to the telescoped flow model: Good match to heads, flows and groundwater age estimates

  21. Similar high permeability zones identified near the other majors springs ?

  22. Conclusions • Spring location controlled by hydrostratigraphy + paleotopography • High permeability layer in shallow bedrock necessary to match observed spring and streamflow

  23. Implications for mitigating effects of urbanization • Limited localized effects of municipal pumping • Critical to maintain recharge in nearby areas

  24. upland sedge fen marsh Vegetation Patterns in Cherokee Marsh Abby McDermott Kurz

  25. Vegetation sampling to quantify diversity Study transect consisting of hand augered wells

  26. Stratigraphy determined from vibracore samples

  27. Four water types based on major ions and other parameters

  28. Interpretation Strong Discharge Weaker discharge, some local recharge Regional discharge blocked by silt loam

  29. Interpretation supported by isotope sampling following summer storms Rain water

  30. 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

  31. Swamp white oak savannah along the lower Wisconsin River Shaili Pfeiffer

  32. Sauk City Dam Inundation Frequency Cambell Bottoms Wisconsin River

  33. Study Site Upper Terrace 500 m Lower Terrace Lake Nested wells Well and multilevel Only multilevel Stage gauge Upper Savanna Lower Savanna River Bank River

  34. Miniature Multilevels Auger Drilling

  35. Comparison of Major Ion Facies Bluff GW River Recent recharge 25% GW+ 75% recharge

  36. Stable Isotopes, June 2000

  37. Stable Isotope Groups

  38. Stable Isotope Profile, June 2000

  39. June 2000 Calcium Isotopes

  40. June 2000 Flooding Calcium Sodium

  41. Conceptual Model as Basis for a Numerical Model

  42. Simulated Flow Paths

  43. June 2000 Calcium Nitrate-N

  44. 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

  45. Some 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

More Related