Technical Reports Document Library

This report summarizes the activities and data collected during the 2001 field operations of the Edwards Aquifer Precipitation Enhancement Program. This was the third year of a program conducted by Weather Modification Inc. (WMI) of Fargo, North Dakota, for the Edwards Aquifer Authority (the Authority) of San Antonio, Texas. The program was funded by the Edwards Aquifer Authority, the Texas Natural Resources Conservation Commission, and the Texas Department of Agriculture, with the sole intent being enhancement of precipitation through cloud seeding. The project area covered 6.37 million acres across south Texas, including all or parts of the following 12 counties: Bandera, Bexar, Blanco, Caldwell, Comal, Guadalupe, Hays, Kendall, Kerr, Medina, Real, and Uvalde. Seeding operations were conducted 24 hours-a-day, seven days a week from April 15 through September 15.

The facilities and procedures for this project were as follows: One C-band weather radar, computers, and a communications system were set up at the centrally located Hondo Regional Airport in Hondo, Texas, to monitor storms and control aircraft. The radar operated continuously throughout the five-month period. The storms, as detected by radar, were posted on the WMI Internet Home Page at 15-minute intervals, thus allowing remote near real-time viewing of operations. Two specially equipped cloud seeding aircraft were dedicated to the project; both were stationed in Hondo. On August 13, 2001, a hangar containing one of the aircraft caught fire and was destroyed, along with the aircraft. A replacement aircraft arrived at Hondo on August 14. Both aircraft were relocated to the Castroville Airport, 15 miles east of Hondo, on the morning of August 14.

High yield formulations of silver-iodide pyrotechnics and acetone solutions were used to generate high concentrations of very fast acting ice-nuclei. High performance aircraft crewed by experienced pilots and directed by experienced radar meteorologists treated developing regions of the storms by direct injection with the seeding agents.

The 2001 field program successfully achieved its objective, to seed those cells thought to have the potential to produce precipitation. During the five-month project, the two aircraft safely completed 58 flights totaling 152 hours 58 minutes. A total of 21.7 kg of seeding agent was dispensed in the form of 834 ejectable flares and approximately 82.8 gallons of silver iodide – acetone solution, which was burned in wing-tip generators.

This final report for 2001 provides a general overview of the program and describes the methodology used. Pictures, tables, graphs, and references are used to summarize the operational activities. All of the project’s radar data, meteorological data, and reports (weekly operations summaries and monthly reports) have been recorded onto CD-ROM and are available to the Authority.