Environmental Flows in Water Availability Modeling

Abstract

The Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) System created pursuant to the 1997 Senate Bill 1 consists of the Water Rights Analysis Package (WRAP) and WRAP datasets for all of the river basins of Texas. The Texas Instream Flow Program was created by the Texas Legislature with its 2001 Senate Bill 2. The 2007 Senate Bill 3 established a new regulatory approach to provide for environmental flow needs of the river systems of Texas with flow standards developed through a stakeholder process culminating in TCEQ rulemaking. TR-440 explores recently expanded WRAP/WAM modeling capabilities for modeling environmental flow requirements established through the Senate Bill 3 process and evaluating their impacts on other water rights. The Brazos WAM is used as a case study to illustrate both daily and monthly modeling capabilities. The datasets developed for the case study are not designed for direct application in the water rights permitting process but rather to develop, test, and demonstrate recently expanded capabilities for modeling environmental flows.