GPS Measurement Method
. Using dual-frequency, full-wavelength GPS instruments (with geodetic antennas), data is collected at 30-second intervals and averaged over 24 hours.
Transition from Conventional Surveying to GPS Technology
Stable borehole extensometers (described subsequently) were equipped with GPS antennas mounted to the inner pipe to measure subsidence and act as stable benchmark.
Conventional Measurement Method
The traditional method used to measure changes in land surface elevation consisted of the establishment of permanent benchmarks that include precise elevations and coordinates for each point.
Can I buy groundwater credits somewhere else?
It is possible to purchase credits on the open market. The District maintains a list of organizations/individuals who have notified the District of their willingness to sell their credits to a third party. The District does not participate in the resale of credits. Please contact the District at 281-486-1105 or info@subsidence.org if you would like more information on credit transfer and purchase.
What is a disincentive fee?
If you are unable to meet the required conversion to alternative water, then you may be subject to a disincentive fee. See our schedule of fees for the current disincentive fee rate.
Can I combine Series A and B groundwater credits?
Yes, as long as the groundwater credits are valid and have not expired, they can be combined.
Can I use Series A groundwater credits?
Valid Series A groundwater credits may be used until expired.
Can I buy Series A groundwater credits?
Although the District no longer issues Series A groundwater credits, there are entities that are willing to sell their A groundwater credits, please contact the District if you would like information on those entities that have notified the District that they are willing to sell their A credits.
Are there currently different types of credits to sponsor?
No, currently each sponsorship (which includes one student in the school program and all of the other aspects of the program) issues 84,000 in Series B groundwater credit which can be used for up to 30% of the permittees total water demand and expires 20 years from issue date.
Are there different types of credits?
Yes, historically the District has issued Series A credits which could be used for 100% of a permittee total water demand and expired 40 years from the date of issue. After an evaluation of the credits potential impact on the District’s mission to prevent future subsidence in 2001, the District discontinued issuing Series A groundwater credits and replaced them with the Series B groundwater credits.