Predicts drought: Modeling system monitors soil moisture

A Texas Agricultural Experiment Station researcher is near completion of a computer modeling system that could help farmers, ranchers and forestland managers minimize the effect of drought and guard against forest and range fires.

With Texas having endured multi-billion dollar losses from drought and wildfires throughout the 1990s, Dr. Raghavan Srinivasan has led efforts to develop a drought warning and monitoring system. The system indexes soil moisture data recorded from 200 weather stations throughout Texas.

The drought monitoring system utilizes remote sensing data derived from Next Generation Weather Radar (NEXRAD), a satellite called the Advanced Very High Resolution Radiometer (AVHRR), NOAA weather feeds, and other satellites. The satellites can track weather patterns, as well as moisture and vegetation readings on various Texas rangeland.

Perhaps the biggest advantage is the information is accessible 24 hours a day via the World Wide Web, providing real-time information to county officials, agricultural producers and others.

“This system will primarily allow farmers, ranchers and forest managers to identify within (approximately 6.2 square miles) whether there is sufficient moisture to plant. Using maps generated by the program, users can determine the degree of drought stress on grazing lands and forests and the risk of forest and grass fires.

“Or (land managers) can compare recent rainfall with historical conditions to help plan for the upcoming growing season,” Srinivasan said.

“For irrigated agriculture, producers can use the new system to decide how much irrigation water is needed by thirsty crops. More importantly, (this system) can help prevent huge costs incurred by farmers, whether due to irrigation costs, fertilizer costs, etc. This system could also be a valuable tool for county officials in determining whether to enforce burn bans.”

In 1998, the Texas Legislature designated funds for increased research and projects to help better manage water and monitor drought as part of the Texas Water Initiative. The drought monitoring project is a partnership made up of several state agencies, which include the Texas Agricultural Experiment Station, Spatial Sciences Laboratory at Texas A&M, the Blacklands Research and Extension Center in Temple — which is part of the Texas A&M University System — the Texas Forest Service, and the Texas Water Resources Institute.

Currently, the monitoring system can only be used at the county level.

“Every five counties is using just one weather station,” Srinivasan said.

For now, county officials are relying on the Keetch-Byram Drought Index (KBDI) monitored by the Texas Forest Service in deciding to implement burn ban declarations. However, the installation of new weather stations at various points across the state will allow more precise monitoring data in specific locations.

“Land use and weather information help us can to better monitor drought,” Srinivasan said. And monitoring soil moisture with a soil moisture index is just one part of the research.

“We want to gather soil moisture indices just like we use in the Palmer Drought Index,” he said. “We want to develop weekly drought indices. We are using real-time land use data, which indicates if a certain piece of land is being used for agricultural purposes, for forestry, or it's simply non-farmed rural land, etc. We now want to propose compiling a soil moisture index to more accurately monitor drought conditions.”

Dr. Travis Miller, Extension program leader for soil and crop sciences at Texas A&M, said the monitoring system will be a more efficient and accurate tool to monitor drought. He said most states in the U.S. report weather conditions and drought conditions using weather conditions derived from eight to 10 weather reporting districts.

“We currently accumulate and summarize weather information in 10 districts, which average more than 26,000 square miles in size,” Miller said. “In some of these districts, only two effective weather stations are used to extrapolate data. This gives us a very ineffective means of assessing moisture conditions and issuing drought declarations necessary for water conservation plans.

“What Dr. Srinivasan is working on is real-time data on a very detailed scale so that we can watch drought conditions develop and develop strategies with respect to agricultural science and government policy to assist people of the state affected by drought conditions.”

To learn more about the monitoring system, go to the Web at

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