**5.3 Water rights analysis package (WRAP) modeling system**

Development of WRAP at Texas A&M University began in the late 1980's sponsored by a cooperative research program of the U.S. Department of the Interior and Texas Water Resources Institute (TWRI). WRAP has been greatly expanded since 1997 under the auspices of the Texas Commission on Environmental Quality (TCEQ) in conjunction with implementing a statewide Water Availability Modeling (WAM) System (Wurbs, 2005b). The Texas Water Development Board, USACE, and other agencies have also sponsored improvements to WRAP. The software and documentation (Wurbs 2009, 2010, 2011a, 2011b; Wurbs and Hoffpauir 2011) are available at the website in Table 1.

WRAP is generalized for application to river/reservoir systems located anywhere in the world, with model-users developing input datasets for the particular river basins of concern. For studies in Texas, publicly available TCEQ WAM System datasets are altered as appropriate to reflect proposed water management plans of interest, which could involve changes in water use or reservoir/river system operating practices, construction of new facilities, or other water management strategies. The WAM System consists of the generalized WRAP along with input datasets for the 23 river basins of Texas that include naturalized stream flows at about 500 gauged sites, watershed parameters for distributing these flows to over 12,000 ungauged locations, 3,450 reservoirs, water use requirements associated with about 8,000 water right permits reflecting two different water right systems, two international treaties, and five interstate compacts. WRAP is applied routinely with the WAM System input datasets for the individual river basins by water management agencies

to the 1970's. The USBR has been a primary sponsor of continued model improvements at Colorado State University. MODSIM has been applied in studies of a number of river systems in the western U. S. and throughout the world by university researchers in collaboration with various local, regional, and international water management agencies. The software, users manual, tutorials, and papers describing various applications are

MODSIM provides a graphical user interface and a general framework for modeling. A river/reservoir system is defined as a network of nodes and links. The objective function (Equation 1) consists of the summation over all links in the network of the flow in each link multiplied by a priority or cost coefficient. The objective function coefficients are factors entered by the model-user to specify relatively priorities that govern operating decisions. The coefficients could be unit monetary costs or more typically numbers without physical significance other than simply reflecting relative operational priorities. An iterative algorithm deals with nonlinearities such as evaporation and hydropower computations. The network flow programming problem is solved for each individual time interval. Thus,

Monthly, weekly, or daily time steps may be adopted for long-term planning, medium-term management, and short-term operations. A lag flow routing methodology is used with a daily time step. The user assigns relative priorities for meeting diversion, instream flow, hydroelectric power, and storage targets, as well as lower and upper bounds on the flows and storages computed by the model. Optional capabilities are also provided for simulating

Development of WRAP at Texas A&M University began in the late 1980's sponsored by a cooperative research program of the U.S. Department of the Interior and Texas Water Resources Institute (TWRI). WRAP has been greatly expanded since 1997 under the auspices of the Texas Commission on Environmental Quality (TCEQ) in conjunction with implementing a statewide Water Availability Modeling (WAM) System (Wurbs, 2005b). The Texas Water Development Board, USACE, and other agencies have also sponsored improvements to WRAP. The software and documentation (Wurbs 2009, 2010, 2011a, 2011b;

WRAP is generalized for application to river/reservoir systems located anywhere in the world, with model-users developing input datasets for the particular river basins of concern. For studies in Texas, publicly available TCEQ WAM System datasets are altered as appropriate to reflect proposed water management plans of interest, which could involve changes in water use or reservoir/river system operating practices, construction of new facilities, or other water management strategies. The WAM System consists of the generalized WRAP along with input datasets for the 23 river basins of Texas that include naturalized stream flows at about 500 gauged sites, watershed parameters for distributing these flows to over 12,000 ungauged locations, 3,450 reservoirs, water use requirements associated with about 8,000 water right permits reflecting two different water right systems, two international treaties, and five interstate compacts. WRAP is applied routinely with the WAM System input datasets for the individual river basins by water management agencies

decisions are not affected by future inflows and future decisions.

salinity and conjunctive use of surface and ground water.

**5.3 Water rights analysis package (WRAP) modeling system** 

Wurbs and Hoffpauir 2011) are available at the website in Table 1.

provided at the website in Table 1.

and consulting engineering firms in regional and statewide planning studies, administration of the water right permit system, and other water management activities.

WRAP simulates water resources development, management, regulation, and use in a river basin or multiple-basin region under a priority-based water allocation system. In WRAP terminology, a water right is a set of water use requirements, reservoir storage and conveyance facilities, operating rules, and institutional arrangements for managing water resources. Stream flow and reservoir storage is allocated among users based on specified priorities, which can be defined in various ways. Simulation results are organized in optional formats including entire time sequences, summaries, water budgets, frequency relationships, and various types of reliability indices. Simulation results may be stored as DSS files accessed with HEC-DSSVue for plotting and other analyses (Hydrologic Engineering Center, 1995, 2009).

WRAP modeling capabilities that have been routinely applied in the Texas WAM System consist of using a hydrologic period-of-analysis of about 60 years and monthly time step to perform water availability and reliability analyses for municipal, industrial, and agricultural water supply, environmental instream flow, hydroelectric power generation, and reservoir storage requirements. Recently developed additional WRAP modeling capabilities include: short-term conditional reliability modeling; daily time step modeling capabilities that include flow forecasting and routing and disaggregation of monthly flows to daily; simulation of flood control reservoir system operations; and salinity simulation.
