Evaluation of Subsidence Impacts on Flooding in the Spring Creek Watershed
As the Subsidence District moves forward with the Joint Regulatory Plan Review, the District is working in collaboration with the Harris County Flood Control District (HCFCD) on a study to better understand the impact of subsidence on the watershed scale.
The goal of the study is to evaluate how subsidence impacts flood risk along Spring Creek. Study findings will provide an important perspective on subsidence impacts related to non-coastal flooding, the benefits of future groundwater conversion within the District, and regional groundwater management decisions.
What is the Spring Creek Watershed?
Spring Creek runs along the northwestern border of Harris County, separating it from Montgomery and Waller Counties. According to the HCFCD, the Spring Creek watershed covers over 284 square miles, with over 225 acres of the watershed located within Waller and Montgomery Counties. Spring Creek has a natural channel with limited conveyance and a larger natural floodplain than other streams in Harris County.
There are numerous parks and protected greenways along the creek, providing an opportunity for recreation as well as preservation of the riparian areas along the creek. The watershed also includes portions of the recharge zone for the Chicot aquifer, which is an important groundwater source for our region.
The study area for this project focused on the entire Spring Creek watershed for hydrology, and on the mainstem of Spring Creek from the Waller County line to its confluence with the West Fork of the San Jacinto River for hydraulics and changes in flood risk. Exhibit 1 shows the limits of the Spring Creek watershed, and the limits of the hydraulic study.
Spring Creek Study Details
The study will develop a method to incorporate subsidence into the existing terrain for two subsidence scenarios (in addition to current conditions), develop hydrologic and hydraulic modeling for each subsidence scenario, quantify impacts of subsidence to riverine flood risk and economic impacts for each scenario, and prepare documentation of the study.
The subsidence scenarios that are being evaluated will approximate the following:
- full implementation of the HGSD 2013 Regulatory Plan and maintain current supply diversification in Montgomery County; and
- full implementation of the HGSD 2013 Regulatory Plan and increased reliance on groundwater in Montgomery County.
The Spring Creek watershed is largely undeveloped, with the exception of the City of Tomball, the Woodlands Township, and the Magnolia, Spring and Kingwood areas. However, the Spring Creek Watershed is currently undergoing development, and the study will differentiate between the increases in flood risk attributable to subsidence from the increases attributable to projected future development across the watershed.
The project deliverables will include a comprehensive report that will document the objectives, approach, assumptions, methodology, and results. Accompanying map exhibits will be developed to depict change in flood risk along the main stem of Spring Creek. In addition, an ArcGIS story map will be developed to provide an executive summary of the project, using maps and tables to depict the results.
Project Team
- Michael Baker International, with Seagull PME, 5engineering, University of Houston
- INTERA