Introduction

Introduction

During the initial phase of the Regional Groundwater Science Partnership, HARC held a series of introductory conversations with a variety of entities, such as community organizations, local groundwater districts, river authorities, subsidence districts, utility districts, local elected officials, chambers of commerce, and municipalities. Based on themes that emerged from those stakeholder conversations, theGroundwater Science Advisory Committee (SAC) developed a report1 (hereafter Review and Recommendations report) that reviewed a recently published technical memorandum prepared for the Lone Star Groundwater Conservation District (LSGCD) titled, “Subsidence Investigations – Phase 1 Assessment of Past and Current Investigations”. An important finding from the SAC’s Review and Recommendations report is that the current state of the science on the Jasper Aquifer supports that the aquifer is likely susceptible to compaction and that it is important to verify this conclusion with further study and monitoring. The technical memorandum Phase 1 report submitted to the Lone Star Groundwater Conservation District by its consultants included possible tasks for a Phase 2 study. The SAC’s Review and Recommendations report assessed these tasks and made recommendations for the proposed Phase 2 study.

The SAC supported several of the Phase 2 recommendations made by the District’s consultants, such as the installation of one or more borehole extensometers to measure compaction particularly in the Jasper Aquifer and further expanded on some items from that report. The SAC suggested that the integrated extensometer and Global Positioning System (GPS) system installed near Katy, TX by the US Geological Survey (USGS)and Fort Bend Subsidence District serves as a cost-effective model todifferentiate shallow and deep compaction within different aquifers. The SAC recommended assessing this approach for application in Montgomery County. The SAC made other specific recommendations for further study, such as incorporating Interferometric Synthetic Aperture Radar (InSAR) into the work in an integrated manner, expanding the GPS network into Montgomery County, and working with local entities familiar with GPS datasets, such as the Harris-Galveston Subsidence District, to establish a dense GPS network in Montgomery County. The SAC encourages decision-makers to work with area scientists and experts on data collection, data analysis, and regional studies.The SAC suggested the installation of at least twenty new continuous GPS stations co-located or closely spaced with Jasper Aquifer groundwater wells and regular water level monitoring. Within three years, residents and decision-makers would have new insights into ongoing subsidence. This methodology will commence a proper assessment of subsidence risks, if any, and help guide any remediation actions.

After the release of the SAC’s Review and Recommendations report, the Groundwater Research Consortium and several stakeholders expressed interest in detailed recommendations from the

1 Review and Recommendations on “Subsidence Investigations – Phase 1” Report, 2021, prepared for the Regional Groundwater Science Partnership, Houston Advanced Research Center, The Woodlands, Texas, 14 pp. www.harcresearch.org/research/rgwsp