Development and Validation of the Texas Best Management Practice Evaluation Tool (TBET)

Authors: White, Michael; Harmel, Daren; HANEY, RICHARD

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2012
Publication Date: 12/1/2012
Citation: White, M.J., Harmel, R.D., Haney, R.L. 2012. Development and Validation of the Texas Best Management Practice Evaluation Tool (TBET). Journal of Soil and Water Conservation. 67(6):525-535.

Interpretive Summary: Conservation planners need more effective tools to assess the effect of adding conservation practices on agricultural fields. The Texas Best management practice Evaluation Tool (TBET) is a simplified model based tool which predicts runoff, sediment, and nutrient losses from fields in Texas. This tool was successfully tested with measured field data. TBET is being used by state conservation planners throughout Texas, allowing improved conservation practice selection and evaluation.

Technical Abstract: Conservation planners need simple yet accurate tools to predict sediment and nutrient losses from agricultural fields to guide conservation practice implementation and increase cost-effectiveness. The Texas Best management practice Evaluation Tool (TBET), which serves as an input/output interpreter and vastly simplified interface for the Soil and Water Assessment Tool (SWAT), was developed to predict mean annual runoff, sediment, N, and P losses from agricultural fields in Texas under a variety of management scenarios and conservation practices. TBET was developed to provide a scientific basis for decision-making, evaluation, and reporting in state and federal conservation programs. A rigorous, data intensive calibration and validation process was employed in TBET development. First, hydrology outputs were calibrated with basin scale streamflow data from 20 USGS sites. Then, runoff, sediment, total N, and total P outputs were calibrated and validated with measured field scale data (260+ site years). Even without calibration, TBET was able to make “good” to “very good” predictions of mean annual runoff and total P losses according to commonly applied model evaluation methods. Calibrated TBET predictions of sediment and total N losses were not as accurate but were still “satisfactory.” These much improved results relative to those of often applied tools such as P Indices are very encouraging since the design goals of simple operation and accurate predictions for diverse Texas conditions with only readily available inputs were certainly met. Thus, TBET meets an important need by providing accurate, science-based estimates of conservation practice benefits at the field scale and allows improved conservation practice selection and cost-effectiveness.