WHO WE ARE
The Harris-Galveston Subsidence District (HGSD) is a special-purpose district created by the Texas Legislature in 1975 to regulate groundwater withdrawal in Harris and Galveston counties to end subsidence. It is the first district of its kind, governed by an appointed Board of Directors, and self-funded through permit fees. HGSD has been internationally recognized for its adaptive management strategy and approach to groundwater regulation, advanced science and research, dedication to regional collaboration, and award-winning water conservation programs.
WHAT WE DO
In this region, groundwater withdrawals have led to subsidence, or the land sinking. To prevent further subsidence, reliance on groundwater must be reduced. HGSD applies a science-based Regulatory Plan that establishes guidelines for groundwater withdrawals through a well-permitting process to reduce reliance on groundwater. The Regulatory Plan is an adaptive management strategy that is regularly reviewed using the best available data to ensure it is effective in preventing further subsidence. The District also provides water conservation tools and resources to further reduce reliance on groundwater.
WHY IT’S IMPORTANT
HGSD takes great pride in the progress already achieved; however, there is still much work to do to reduce reliance on groundwater and prevent further subsidence. As Texas’s Gulf Coast population grows, the demand for water increases. Our goal is to support this growth by protecting our groundwater resources through effective groundwater regulations backed by the best available science, equipping our communities with water conservation tools and resources, and collaborating with local, state, federal, and international entities to ensure a sustainable water future free from the impacts of subsidence.
Interactive Subsidence Maps
The Harris-Galveston Subsidence District maintains Global Positioning System (GPS) monitoring stations in Harris, Galveston, Fort Bend, and surrounding counties. These sites are being cooperatively run and operated by the following agencies:
The District works with the University of Houston to process the data collected from GPS stations to measure subsidence. For detailed information on the processing methodology, please click here.
This data is used to map the latest subsidence rates and is published in an Annual Groundwater Report each spring.
The District’s Science & Research Program utilizes several scientific methods, technologies, and techniques to measure and monitor subsidence, including satellite remote sensing. Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing technique that uses satellite-based radar images to measure land surface movement by comparing images collected at different times, offering higher spatial resolution than other satellite technologies.
Combining InSAR technology and GPS data, the District created this interactive map to provide a more comprehensive view of subsidence in our region.
- The InSAR data is used to visualize changes in the land surface over time to see whether the surface is moving toward the satellite (uplift) or away from the satellite (subsidence).
- The GPS station data is used to determine the station’s position on the ground and to provide accurate measurements of localized changes. You can click on each GPS station on the map to view specific data for that station, including the years of monitoring and the total amount of subsidence recorded.