Development of a Geospatial Approach for Assessing Groundwater Connectivity for Land Planning Activities

www.ruralgis.org

Understanding groundwater connectivity dynamics is important for:

Project Goals

Model Selection Criteria

Numerical Groundwater Model: MODFLOW

MODFLOW: Conservation of Fluid Mass

MODFLOW Grid Analysis

Data Requirements & Assumptions

Case Studies: Yakima River, Wapato, Washington Nisqually River, Yelm, Washington

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Site Location and Surface Hydrology

Surficial Geology

Slide 15

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Data Collection and Model Development

Data Collection and Model Development

Slide 19

2-Dimensional Perspective of Groundwater Flow Direction within Unconfined Aquifer

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3-Dimensional Perspective of Predicted Flow Paths

Limitations

Strength of modeling approach:

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Acknowledgements

References

Groundwater Modeling

System processes

Policy case study: Shorelands and Associated Wetlands

Considering all the factors

‘Grey Areas’

Associated Wetland assessment using MODFLOW

Case Study 1: Yelm, Thurston County, WA

Designated SMA Streams

Area of Interest and Local Wetlands

FEMA extents and NWI Wetlands

FEMA extents and NWI Wetlands

Are these ‘Associated Wetland’?

MODFLOW

Modeling Objectives

Data Collection

Public Data Resources

Define Conceptual Model Boundaries

Area of Interest - Yelm

Geologic Stratigraphy

Well Locations

Hydrogeologic Cross-Section

Hydrogeologic Cross-Section

Hydrogeologic Interpretation: Aquifers

Geologic Unit Representation within the model

Model Construction

Water Table Elevations

Boundary Conditions & Assumptions

Results: Projected Groundwater Flow Paths

Pathline Direction

Conclusions

Strengths & Limitations of Approach

Slide 59

Regional Stratigraphy

SMP Example: Yakima County– Current & Proposed Streams

Slide 62

Determination of Wetland Hydraulic Connectivity…Why?

Why model?

Numerical Groundwater Model