Extensions to the Water Rights Analysis Package Modeling System

Abstract

The Water Rights Analysis Package (WRAP) simulates management of the water resources of a river basin or multiple-basin region under a priority-based water allocation system. The model facilitates assessments of hydrologic and institutional water availability and reliability in satisfying requirements for instream flows, water supply diversions, hydroelectric energy generation, and reservoir storage. Basin-wide impacts of water resources development projects and management practices are modeled. The Texas Commission on Environmental Quality (TCEQ), its partner agencies, and contractors implemented a statewide Water Availability Modeling (WAM) System based on WRAP during 1997-2003 pursuant to comprehensive water management legislation enacted by the Texas Legislature in 1997. Expanded modeling capabilities developed since implementation of the Texas WAM System are designed to support a broader range of decision support needs as well as better address issues identified during implementation of the WAM System. Recent extensions to WRAP involve adding (1) conditional reliability modeling capabilities, (2) daily time step features including flow forecasting and routing, (3) features for simulating flood control operations, and (4) a salinity simulation component. WRAP Modeling System The WRAP model simulates capabilities of river/reservoir systems in meeting specified water management/regulation/use requirements for given sequences of naturalized streamflows and reservoir net evaporation rates. Water management is combined with natural hydrology. Water managers are concerned with future not past hydrologic conditions. However, since the future is unknown, historical hydrology is typically used to capture the hydrologic characteristics of a river basin. In WRAP terminology, water use requirements and reservoir and river system operating strategies are called water rights. The water management/use scenario might be actual current water use, projected future conditions, the premise that all permit holders use their full authorized amounts, or some other scenario of interest.