Fort Hood BRASS


Fort Hood is a 217,000 acre United States Army base located in Bell and Coryell Counties of Central Texas. Fort Hood is the only post in the United States capable of stationing and training two Armored Divisions.

Training conditions and wildfire risk are directly related to the state and condition of the vegetation within the Fort Hood military base. Dense stands of perennial grasslands are preferred for reducing erosion; however, these plant communities pose a high potential for wildfire risk during dry, windy weather conditions. It is estimated that approximately 30-days of military training time is lost annually to wildfire related activities. Monitoring vegetation and fire conditions are of key importance to the sustainability of training activities that occur within the Fort Hood military base.

The objective of the vegetation and fire monitoring system is to inventory, monitor, evaluate, and integrate land condition trends and capabilities with Fort Hood training requirements to enhance, improve, repair, and sustain training land management on the installation. Texas Agrilife Research has entered into a 4-year agreement with Fort Hood to develop this system using a viable Phytomass Plant Growth model (PHYGROW) and a Burning Risk Advisory Support System (BRASS).  

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Texas Agrilife Research began its involvement with Fort Hood in 2003 under the leadership of Wayne Hamilton in the Department of Ecosystem Science and Management.  The initial work efforts included a vegetation inventory analysis as it relates to sustainable livestock stocking rate recommendations for the installation.

Texas Agrilife Research contracted with the Department of Defense in 2007 to develop the vegetation and fire monitoring system for the Fort Hood Military Reservation.

Field Data Collection

Field collected vegetation data is necessary to parameterize and validate the PHYGROW growth model.  The PHYGROW sample points have been distributed across the landscape based on unique plant communities.  The plant communities were established using a combination of unique spectral characteristics of the vegetation obtained from satellite imagery, unique ecological sites, and major land use areas of the base.  For the initial field data collection at each sample point, the species composition, litter production, and herbaceous production parameters are determined along a permanent transect.  At subsequent annual validation samples, litter and herbaceous production are determined using 1/4 meter quadrats and oven dry weights at 10 plots along the transect.

PHYGROW field sampling began in summer 2006 when an initial 121 sites were sampled.  The majority of these sites (116) match the Land Condition Trend Analysis (LCTA) points where a history of sample data has been established by the Natural Resources Conservation Service (NRCS).  An additional 63 sites were added in summer 2007 that were selected using a Most Similar Neighbor (MSN) analysis of 2006 data.  Field work completed during summer 2007 produced second year validation samples of 114 sites and first year samples of 62 sites.  Work efforts during years 2006 and 2007 yielded a total of 184 sample locations on Fort Hood. Subsequent field work efforts in 2008 and 2009 have yielded third year validation samples at each of the 184 sample locations on the base.

Sampling Points

Field Identification

Landscape Modeling

The BRASS decision support tool provides a continuous means for Fort Hood resource managers to assess vegetation and weather to support decisions related to prescribed burning and/or the risk of wildfire. The BRASS system is composed of two main components, the PHYGROW growth model and the PHYRESIM burning model.  PHYRESIM was developed from a software toolkit called Firelib, which is the same toolkit that drives the highly respected BEHAVE burning application. Firelib was developed by the US Forest Service as a toolkit to build custom BEHAVE type applications.

The PHYGROW model is a near-real time plant growth model that is updated daily utilizing current and forecasted weather conditions from the National Oceanic and Atmospheric Administration (NOAA).  A PHYGROW model has been calibrated for each of the major plant communities and ecological sites within the base, which will continuously monitor vegetation production and fuel load conditions. 

In order to distribute the modeled point data across the landscape, a methodology developed by the US Forest Service has been implemented called Most Similar Neighbor (MSN).  First, a landscape map of plant communities is developed within a Geographic Information System (GIS) using available resources such as ecological site maps derived by the Natural Resource Conservation Service (NRCS), plant communities derived from classification of remotely sensed satellite imagery, and supplemental field collected data.  Advanced image processing software (i.e. ERDAS, ENVI, and IDRISI) has facilitated the development of plant community polygons from multispectral satellite imagery.  Next, the necessary PHYGROW and BRASS field sample data is collected for a minimum of one polygon within each unique plant community.  The field collected dataset is then distributed across the landscape by matching similar non-sampled plant community polygons as determined by the MSN analysis with field sample data collected within the sampled polygons.

Vegetation Classes

Vegetation conditions on Fort Hood are constantly changing due to controlled burns and wildfires, training activity, and restoration practices such as brush clearing and reseeding.  Therefore, the MSN polygons will be continuously updated to reflect the most currently available base conditions using remotely sensed satellite imagery.  Significant disturbances within the plant communities due to training activity and restoration practices can be detected using higher resolution satellite imagery such as 10 and 20-meter SPOT or 30-meter LANDSAT obtained during key times of the year.

The PHYGROW output is integrated with the fire behavior model, PHYRESIM, to provide a continuously updated fire risk map for an area. PHYGROW outputs current live herbaceous moisture, live herbaceous production, 1-hr. fuel accumulation, live wood moisture, and live wood production to the PHYRESIM subsystem on a daily basis.  PHYRESIM coordinates the fuel moisture stick model and PHYGROW outputs with NOAA current and forecasted weather data to produce a 7 day forecast updated at 6 hour intervals.  Changing weather conditions and fluctuating plant communities create dynamic BRASS 30-minute burn area, flame length, spread rate, and fuel moisture outputs. This data can be used to a priori select areas with adequate fuel-load and appropriate weather conditions for a prescribed burn, as well as, determine wildfire risk conditions.

Burn Area

Product Delivery

The final delivery for this 4-year project is termed BRASS-MIL (Burning Risk Advisory Support System for Military Training Lands).  The product will utilize the vegetation and fire modeling outputs described above to develop real-time 30 and 60-minute burned area polygons on a computer system located in the range area control room at Fort Hood. 

The product works in conjunction with the Graphic Fire Desk (GFD) to produce a seamless process for visualization of fire spread down range.  The system also works as a reporting tool for historical fire locations.  The technology parallels the Range Facility Management Support System (RFMSS) to assist in determining which active ranges are affected by fire and who needs to be evacuated.

Fire conditions can also be assessed for any point on the base via the internet to assist controlled burn crews, fire fighters, and other groups associated with the ranges that do not have direct access to the Fort Hood Control Room.  Additional range information such as vegetation production, drought prediction, and historical ranking is also delivered through the internet.  The BRASS-MIL system also captures two 10-meter SPOT images each year which are used for ground cover change detection, vegetation trends, and can indicate areas for vegetation management programs.

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