Water Availability Modeling System Research Articles

Water Rights Analysis Package Modeling System

The water rights analysis package simulates surface water development, allocation, management, and use and performs reliability and frequency analyses of simulation results. The computer modeling system facilitates assessments of hydrologic and institutional water availability and reliability in satisfying requirements for reservoir storage, water supply diversions, environmental instream flows, and hydroelectric energy generation. Reservoir system operations for flood control can be simulated. Capabilities are also provided for tracking salinity concentrations. Basin-wide impacts of water resources development projects and management practices are modeled. The modeling system is generalized for application anywhere, with input datasets being developed for particular river systems of concern. The water availability modeling system maintained by the Texas Commission on Environmental Quality and routinely applied by the professional water management community consists of the water rights analysis package and simulation input datasets for all of the river basins of Texas. Model-users modify the input datasets as appropriate to evaluate alternative water use scenarios, development projects, and management strategies of interest. This paper explores concepts and methodologies incorporated in the water rights analysis package and other comparable modeling systems, implementation of water availability modeling in Texas, and contributions to effective water management.

Monthly river flows in Texas for natural and developed conditions

River flow characteristics and computational methods for converting sequences of monthly flows between natural and regulated conditions are explored based on experience in assessing water availability throughout the state of Texas in the United States. Diverse climate, hydrology, economic development, and water management practices across the state combined with continual population growth and implementation of a statewide water availability modeling system makes Texas an excellent case study of stream flow characteristics and modeling and analysis methods that are relevant worldwide. Stream flow is extremely variable, subject to severe multiple-year droughts, intense floods, seasonality, and continuous fluctuation. The effects of population and economic growth, water resources development and management, and climatic variability on river flows vary with different conditions found across the state. The modeling system provides capabilities for adjusting observed river flows to represent natural conditions, simulating regulated flows representing specified conditions of development, and performing statistical frequency and reliability analyses.

Environmental flow requirements in a water availability modeling system

Abstract The Texas Water Availability Modeling (WAM) System consists of the generalized Water Rights Analysis Package (WRAP), which is applicable for river systems located anywhere, and WRAP input datasets for the river basins of Texas. The WRAP/WAM system has been applied for over a decade in planning studies and administration of a water rights allocation system. Environmental flow standards for selected river systems in Texas have recently been established through a legislatively mandated process based on flow regimes with subsistence, base, pulse, and overbank flow components that describe the magnitude, frequency, duration, and timing of flows required to maintain sound ecosystems. WRAP and WAM capabilities for integrating environmental flow requirements in water allocation and associated water availability modeling have been greatly expanded as necessary to implement the new environmental flow standards. The modeling system and lessons learned in its implementation in Texas are relevant elsewhere.

Sustainable Statewide Water Resources Management in Texas

AbstractKey integrated components of the Texas sustainable water management enterprise include a regional and statewide planning process, water rights permit system and other water allocation mechanisms, process for establishing environmental flow standards, and water availability modeling system. These statewide endeavors mandated by the Legislature are implemented by a water management community comprised of state, local, and federal agencies, private industry, stakeholders, interests groups, consulting engineering firms, and university researchers. Texas is a large state with a rapidly growing population, declining groundwater supplies, intensifying demands on limited surface water resources, extreme hydrologic variability including severe droughts, and very diverse climate, geography, economic development, and water management practices. The Texas experience is illustrative of fundamental concepts and issues involved in state-level efforts to achieve sustainable water management.

Institutional and Hydrologic Water Availability in Texas

The Water Availability Modeling (WAM) System created and maintained by the Texas Commission on Environmental Quality (TCEQ) and its partner agencies and contractors consists of the generalized Water Rights Analysis Package (WRAP) developed at Texas A & M University, which may be applied anywhere in the world, and WRAP input datasets for the 23 river basins of Texas. WRAP is designed for assessing river/reservoir system reliabilities in meeting water supply, hydroelectric power, environmental flow, flood control, and reservoir storage needs. The Texas WAM System supports regional and statewide planning, administration of water allocation systems, and other water resources management endeavors. Activities of numerous water management entities operating 3,435 reservoirs and other facilities in accordance with treaties between the United States and Mexico, five interstate compacts, two water right permit systems with 6,000 active permits, and other institutional arrangements are simulated. The modeling system contributes greatly to water management in Texas and continues to be expanded to address additional water management issues. The Texas experience in implementing the WAM System illustrates key aspects of evaluating water availability from institutional as well as hydrologic perspectives.

Modeling river/reservoir system management with the expanded WRAP

The Water Rights Analysis Package (WRAP) is a generalized modeling system for simulating water resources development, management, allocation, and control in river basins located anywhere in the world. WRAP is used to assess reliabilities in meeting water supply, hydroelectric power, and environmental instream flow needs. Capabilities for tracking salinity, assessing short-term reliabilities, and simulating reservoir operations for flood control were recently added. The modeling system continues to be expanded to address a broadening range of applications with major new modeling capabilities being released during 2009–2010. The Texas Water Availability Modeling (WAM) System consists of the generalized WRAP and input datasets for the 23 river basins of Texas. The Texas WAM System supports regional and statewide planning, administration of a water allocation permit system with over 8,000 active permits, and other water resources management functions. Activities of an array of water management entities operating 3,435 reservoirs and other facilities in accordance with various water allocation systems and other institutional arrangements are modeled.

Condensing Water Availability Models to Focus on Specific Water Management Systems

The Texas Water Availability Modeling System is routinely applied in administration of the water rights permit system, regional and statewide planning, and an expanding variety of other endeavors. Modeling water management in the 23 river basins of the state reflects about 8,000 water right permits and 3,400 reservoirs. Datasets are necessarily large and complex to provide the decision-support capabilities for which the modeling system was developed. New modeling features are being added, and the different types of applications are growing. Certain applications are enhanced by simplifying the simulation input datasets to focus on particular water management systems. A methodology is presented for developing a condensed dataset for a selected reservoir system that reflects the impacts of all the water rights and accompanying reservoirs removed from the original complete dataset. A set of streamflows is developed that represents flows available to the selected system considering the effects of all the other water rights in the river basin contained in the original complete model input dataset that are not included in the condensed dataset. The methodology is applied to develop a condensed model of the Brazos River Authority reservoir system based on modifying the Texas Water Availability Modeling System dataset for the Brazos River Basin. Citation: Wurbs RA, Kim TJ. 2010. Condensing water availability models to focus on specific water management systems. Texas Water Journal. 1(1):20-32. Available from: https://doi.org/10.21423/twj.v1i1.1380.

Methods for Developing Naturalized Monthly Flows at Gaged and Ungaged Sites

The state of Texas recently implemented a water availability modeling (WAM) system to support water management activities in its 23 river basins. Hydrology is represented in the modeling system by sequences of naturalized streamflows at all pertinent locations for each month of a several decade long period of analysis. Flows at stream gaging stations are adjusted to remove the effects of historical water resources development and use. The resulting naturalized flows are distributed to numerous ungaged sites of interest in modeling water management. Methods are incorporated into the WAM system for converting gaged flows to naturalized flows and transferring the flows from gaged to ungaged locations. Flow naturalization adjustments consist primarily of removing the effects of historical reservoir storage and evaporation, water supply diversions, and return flows from surface and groundwater supplies, and in some cases other considerations. The WAM system includes several alternative methods for distributing sequences of monthly naturalized flows from gaged to ungaged locations. The option most often used is based on the Natural Resource Conservation Service curve-number-based rainfall-runoff relationship. The methodologies for developing naturalized flows at gaged and ungaged sites incorporated in the Texas WAM system are generally applicable for similar modeling applications in other places.

Incorporation of Climate Change in Water Availability Modeling

The state of Texas recently implemented a water-availability modeling (WAM) system to support planning and regulatory activities. River basin hydrology is represented in the WAM system by sequences of historical monthly naturalized streamflows and net reservoir evaporation rates. This paper describes a case study investigation of the potential effects of climate-change on assessments of water-supply capabilities and focuses on whether and how climate change considerations should be incorporated in the WAM system. A modeling approach was adopted to explore the impacts of climate change on hydrologic and institutional water availability for the numerous water users who depend on supplies provided by the 118,000 km2 Brazos River Basin. Analyses of historical naturalized streamflows indicate hidden but significant multiple-year cycles but no long-term trends during the twentieth century. A climate model and watershed hydrology model are used to adjust the WAM system hydrology to reflect anomalous climate duri...

Texas Water Availability Modeling System

A water availability modeling system was implemented during 1997–2004 by the Texas Commission on Environmental Quality and its contractors, in collaboration with the water management community, under a mandate provided by comprehensive water management legislation enacted by the Texas legislature in 1997. The availability and reliability of water resources are assessed based on simulating river/reservoir system management and water allocation practices using sets of historical naturalized monthly streamflow sequences to represent basin hydrology. The prior appropriation water rights permit system and other institutional mechanisms for allocating streamflow and reservoir storage resources among numerous water users are considered in detail in evaluating basinwide impacts of water management decisions. The generalized modeling system and lessons learned in its implementation in Texas are applicable to river basin management throughout the world.