Browsing by Author "Wurbs, Ralph A."
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Item Comparative Evaluation of Generalized River/Reservoir System Models(Texas Water Resources Institute, 2005-04) Wurbs, Ralph A.This report reviews user-oriented generalized reservoir/river system models. The terms reservoir/river system, reservoir system, reservoir operation, or river basin management "model" or "modeling system" are used synonymously to refer to computer modeling systems that simulate the storage, flow, and diversion of water in a system of reservoirs and river reaches. Generalized means that a computer modeling system is designed for application to a range of concerns dealing with river basin systems of various configurations and locations, rather than being site-specific customized to a particular system. User-oriented implies the modeling system is designed for use by professional practitioners (model-users) other than the original model developers and is thoroughly tested and well documented. User-oriented generalized modeling systems should be convenient to obtain, understand, and use and should work correctly, completely, and efficiently. Modeling applications often involve a system of several simulation models, utility software products, and databases used in combination. A reservoir/river system model is itself a modeling system, which often serves as a component of a larger modeling system that may include watershed hydrology and river hydraulics models, water quality models, databases and various software tools for managing time series, spatial, and other types of data. Reservoir/river system models are based on volume-balance accounting procedures for tracking the movement of water through a system of reservoirs and river reaches. The model computes reservoir storage contents, evaporation, water supply withdrawals, hydroelectric energy generation, and river flows for specified system operating rules and input sequences of stream inflows and net evaporation rates. The hydrologic period-of-analysis and computational time step may vary greatly depending on the application. Storage and flow hydrograph ordinates for a flood event occurring over a few days may be determined at intervals of an hour or less. Water supply capabilities may be modeled with a monthly time step and several decade long period-of-analysis capturing the full range of fluctuating wet and dry periods including extended drought. Stream inflows are usually generated outside of the reservoir/river system model and provided as input to the model. However, reservoir/river system models may also include capabilities for modeling watershed precipitation-runoff processes to generate inflows to the river/reservoir system. Some reservoir/river system models simulate water quality constituents along with water quantities. Some models include features for economic evaluation of system performance based on cost and benefit functions expressed as a function of flow and storage.Item Comparative Evaluation of Methods for Distributing Naturalized Streamflows from Gaged to Ungaged Sites(Texas Water Resources Institute, 1999-08) Sisson, Emery; Wurbs, Ralph A.The investigation documented by this report consists of identifying, developing, and evaluating alternative approaches for estimating sequences of monthly naturalized streamflows at ungaged sites based on known naturalized flows at gaged locations. The ultimate product of the study is a recommended set of flow distribution methodologies for incorporation into the Water Rights Analysis Package (WRAP) model (Wurbs 1999). The objectives of the investigation are: * To analyze relationships between flows from different subwatersheds of river basins and the watershed characteristics governing these relationships * To evaluate alternative methodologies and associated parameters for transposing flows from gaged to ungaged locations * To develop a recommended set of procedures for transposing flows from gaged to ungaged locations for incorporation into WRAPItem Evaluation of Storage Reallocation and Related Strategies for Optimizing Reservoir System Operations(Texas Water Resources Institute, 1988-08) Carriere, Patrick E.; Wurbs, Ralph A.Statement of the Problem Rapid population and economic growth combined with depleting groundwater reserves are resulting in ever increasing demands on surface water resources in Texas, as well as elsewhere. The climate of the state is characterized by extremes of floods and droughts. Reservoirs are necessary to control and utilize the highly variable streamflow. Due to a number of economic, environmental, institutional, and political considerations, construction of new reservoir projects is much more difficult now than in the past. Consequently, optimizing the beneficial use of existing reservoirs is becoming increasingly more important. Reservoir operation is based on the conflicting objectives of maximizing the amount of water available for conservation purposes and maximizing the amount of empty space available for storing future flood waters to reduce downstream damages. Common practice is to operate a reservoir for either flood control only, conservation only, or a combination of flood control and conservation with separate pools designated for each. The conservation and flood control pools, or vertical zones, in a multipurpose project are fixed by a designated top of conservation (bottom of flood control) pool elevation. Conservation pools may be shared by various purposes, such as water supply, hydroelectric power, and recreation, which involve both complementary and conflicting interactions. Public needs and objectives and numerous factors affecting reservoir operation change over time. An increasing necessity to use limited storage capacity as effectively as possible warrants periodic re-evaluations of operating policies. Reallocation of storage capacity between purposes represents a general strategy for optimizing the beneficial use of limited storage capacity in response to changing needs and conditions. A storage reallocation between flood control and conservation purposes typically involves a permanent or seasonal change in the designated top of conservation pool elevation. Reallocations between conservation purposes can be achieved by various modifications of operating policies. Although given relatively little consideration in the past, storage reallocations will likely be proposed more frequently as demands on limited resources increase. Scope of Study This report documents an investigation of: (1) the potential of storage capacity reallocation and other related modifications in operating policies as management strategies for optimizing the beneficial use of existing reservoirs in Texas and (2) modeling capabilities for formulating and evaluating such changes to operating policies. In general, storage reallocations can involve a variety of types of reservoir use. The present study focused primarily on flood control and water supply. Multiple purpose reservoir operations involving hydroelectric power were also investigated. Both permanent conversion of storage capacity between purposes and seasonal rule curve operations were addressed. Buffer pool operations were also considered. Multiple reservoir system operation was a major emphasis of the study. The literature was reviewed and several reservoir management agencies contacted to (1) identify experiences in studying and/or implementing storage reallocations and (2) evaluate the state-of-the-art of associated modeling and analysis capabilities. The feasibility of seasonal rule curve operation depends upon the seasonal characteristics of the various factors affecting reservoir operation. Precipitation, streamflow, reservoir evaporation, water demands, and reservoir storage content data for Texas were analyzed to identify seasonal characteristics. A 12-reservoir system operated by the U.S. Army Corps of Engineers and Brazos River Authority provided a case study for evaluating the potential for storage reallocations and related operating strategies. This system, located in the Brazos River Basin, is considered representative of major reservoirs in Texas. The existing operating policies and possible modifications were investigated. The case study includes (1) flood control storage frequency and conservation drawdown frequency analyses based on the results of monthly hydrologic period-of-record simulations of reservoir system operations and (2) firm yield and reliability analyses. The generalized computer programs HEC-3, HEC-5, STATS, and MOSS-IV, and several utility software packages were used in the modeling study. Simulation of reservoir system operations was based on an 85-year sequence of monthly hydrologic data. The case study provides a preliminary assessment of the viability of permanent storage conversions and/or adoption of seasonal rule curve operations as potential reservoir management strategies. The objective is to evaluate storage reallocation potentialities in general, not develop detailed reallocation plans. The case study is basically a reconnaissance-level hydrologic analysis of reservoir operations. The monthly period-of-record simulations provide a reasonably precise analysis of water supply considerations. However, the daily hydrologic data required for detailed analysis of flood control operations were not included in the study. Reallocation of reservoir storage capacity involves complex institutional, financial, economic, legal, political, and technical considerations not addressed in the case study. However, the hydrologic analyses provide a good starting point for determining what types of reallocation strategies and modeling approaches might be potentially effective and whether more detailed studies are worthwhile. Organization of the Report Chapter 2 is a general discussion of reservoir operation and institutional and technical aspects of storage reallocation and a review of reallocations which have been implemented or proposed throughout the nation. Chapter 3 addresses the seasonality of the hydrologic factors pertinent to seasonal rule curve operation in Texas. Chapter 4 reviews state-of-the-art modeling capabilities and describes the computer models adopted for use in the case study. The Brazos River Basin case study is presented in chapters 5 through 8. Study results are summarized, and conclusions are presented in chapter 9.Item Fundamentals of Water Availability Modeling with WRAP(Texas Water Resources Institute, 2005-04) Wurbs, Ralph A.Item Hydrologic and Institutional Water Availability in the Brazos River Basin(Texas Water Resources Institute, 1988-08) Walls, W. Brian; Carriere, Patrick E.; Bergman, Carla E.; Wurbs, Ralph A.Statement of the Problem Effective management of its surface water resources is essential to the continued growth and prosperity of the state of Texas. Rapid population and economic growth combined with depleting ground water reserves are resulting in ever-increasing demands being placed upon the surface water resources. The climate of the state is characterized by extremes of floods and droughts. Reservoirs are necessary to control and utilize the highly variable streamflow. Numerous reservoirs have been constructed to facilitate management of the water resources of the various river basins of the state. Effective control and utilization of the water resource supplied by a stream/reservoir system requires an understanding of the amount of water which can be provided under various conditions. Estimates of reservoir yield are a key element in practically all studies and decisions involving development and management of surface water supplies. Yield is defined as the amount of water which can be supplied by an unregulated stream, reservoir, or multiple reservoir system during a specified period of time. The stochastic nature of streamflow must be reflected in methods for quantifying yield. The approaches for expressing yield which traditionally have been used in water supply planning and management are firm yield and, to a lesser extent, reliability. Firm yield is the estimated maximum release or withdrawal rate which can be maintained continuously during a repetition of the hydrologic period-of-record. A number of definitions of reliability are cited in the technical literature. A common definition is that reliability is the percentage of time that a stream/reservoir system is able to meet a specified demand. Precise textbook definitions of firm yield and reliability can be formulated for a simple river basin with one reservoir and one water user. However, in actual practice, for a complex multiple reservoir, multiple user system, firm yield and reliability must be defined in terms of the basic assumptions and approaches used in handling various complicating factors. Water supply planning and management involves complex institutional, environmental, hydrologic, and physical systems. Streamflow, reservoir sedimentation, evaporation, water demands, and other variables pertinent to yield determinations are highly stochastic. Measured historical data is limited in extent and accuracy. The future is always uncertain. Mathematical models only approximate the complexities of reality. Consequently, reservoir yield studies necessarily involve uncertainties and approximations. The availability of water to particular users depends upon legal rights and contractual commitments as well as physical facilities and hydrologic conditions. Reservoir yield is subject to institutional as well as hydrologic constraints. Evaluation of the relationships between water rights and reservoir yield is particularly important at this time in Texas with the recent completion of the water rights adjudication process. Scope of the Study The objective of the study documented by this report was to evaluate and improve state-of-the-art capabilities for estimating reservoir yield. Institutional as well as hydrologic aspects of water availability were investigated. Evaluation of increases in yield achieved by multiple reservoir system operation, rather than separate operation of individual reservoirs, was a major emphasis of the study. The river basin was viewed as an integrated system. The hydrologic and institutional availability of water was investigated for a case study reservoir system. However, the study approach and computer programs used are generally applicable to any reservoir system. Study findings have pertinent implications for water resources management throughout Texas and elsewhere as well as for the specific river basin studied. Water availability is dependent upon institutional constraints and capabilities. The study included a review of water law and other institutional aspects of surface water management in Texas. A literature review was made assessing modeling capabilities for estimating reservoir yield. The reservoir system simulation models HEC-3 and HEC-5 were adopted for use in the case study. These generalized computer programs provide comprehensive capabilities for analyzing the hydrologic aspects of reservoir system operations, but lack the capability to simulate water rights priorities. Consequently, a generalized water rights simulation computer program was developed in conjunction with the study. Other computer programs were used for developing input data and analyzing output from the HEC3, HEC-5, and water rights models. A system of twelve reservoirs in the Brazos River Basin provided a case study. Nine multiple purpose flood control and conservation reservoirs are owned and operated by the Fort Worth District (FWD) of the U.S. Army Corps of Engineers (USACE). The Brazos River Authority (BRA) has contracted for most of the water supply storage capacity of the nine federal projects. The BRA owns and operates three other conservation reservoirs. In addition to the 12-reservoir USACE/BRA system, Hubbard Creek Reservoir, owned by the West Central Texas Municipal Water District, was modeled in detail because of its relatively large storage capacity. The numerous other smaller reservoirs in the basin were considered primarily from the perspective of approximating their impacts on the 12 USACE/BRA reservoirs. Individual reservoir and system firm yields were computed based on alternative conditions of reservoir sedimentation and alternative assumptions regarding multiple reservoir and multiple user interactions. The sensitivity of firm yield estimates to these and other factors was evaluated. A series of yield analyses were made from a strictly hydrologic perspective, without consideration of water rights. Yield analyses were then repeated incorporating water rights constraints. In addition to the firm yield simulations, a basinwide water rights analysis simulation study was performed. The simulations were based on monthly historical period-of-record hydrologic data. The modeling studies provided a basis for evaluating the hydrologic and institutional availability of water in the Brazos River Basin. Organization of the Report An overview of water law and institutions in Texas, from the perspective of surface water Management, is presented in Chapter 2. Surface water Management in the Brazos River Basin is described in Chapter 3. Chapter 4 is 8 discussion of reservoir system yield analysis models in general and the models used in the present study in particular. The Brazos River Basin simulation studies are documented by Chapters 5 through 9. Chapter 5 describes the compilation of basic data used in the study. A detailed hydrologic yield study is documented by Chapter 6. The analyses outlined in Chapter 6 were performed with HEC-3 and HEC-5 and are from a strictly hydrologic perspective, without consideration of water rights. The water rights analyses, utilizing the TAMU Water Rights Analysis Progra , are presented in Chapters 7 and 8. Chapter 7 discusses the results of a simulation of hydrologic and water rights aspects of surface water management in the basin. Firm yields constrained by senior water rights are documented in Chapter 8. Chapter 9 provides a critical evaluation, including sensitivity analyses, of the key factors affecting firm yield estimates. The study summary and conclusions are presented as Chapter 10.Item Natural Salt Pollution and Water Supply Reliability in the Brazos River Basin(Texas Water Resources Institute, 1993-08) Ganze, C. Keith; Saleh, Ishtiaque; Karama, Awes S.; Wurbs, Ralph A.The Brazos River Basin is representative of several major river basins in the Southwestern United States in regard to natural salt pollution. Geologic formations underlying portions of the upper watersheds of the Brazos, Colorado, Pecos, Canadian, Red, and Arkansas Rivers, in the states of Texas, Oklahoma, New Mexico, Kansas, and Colorado, are sources of salt emissions to the rivers. Millions of years ago, this region was covered by a shallow inland sea. The salt-bearing geologic formations were formed by salts precipitated from evaporating sea water. Salt springs and seeps and salt flats in upstream areas of the basins now contribute large salt loads to the rivers. The natural salt contamination significantly impacts water resources development and management. Water quality in the Brazos River is seriously degraded by natural contamination by salts consisting largely of sodium chloride with moderate amounts of calcium sulfate and other dissolved solids. The primary source of the salinity is groundwater emissions in an area of the upper basin consisting of the Salt Fork Brazos River watershed and portions of the adjacent Double Mountain Fork Brazos River and North Croton Creek watersheds. High salt concentrations significantly affect water management and utilization. Water in the three main stream reservoirs is unsuitable for municipal use without costly desalinization processes. The quality of the river improves significantly in the lower basin with dilution from good quality tributaries. Population and economic growth combined with depleting groundwater reserves are resulting in ever-increasing demands on the surface water resources of Texas and the Brazos River Basin. Effective management of the highly stochastic water resources of a river basin requires an understanding of the amount of suitable quality water which can be provided under various conditions. Reservoir system reliability analyses support planning studies and management decisions regarding (1) improvements in reservoir system operating policies, water rights allocations, and water supply contracts, (2) facility expansions and construction of new water supply projects, and (3) projects and strategies for dealing with salt pollution. Consideration of water quality as well as quantity is important in evaluating reservoir system reliability in the Brazos River Basin.Item Optimum Reservoir Operation for Flood Control and Conservation Purposes(Texas Water Resources Institute, 1985-11) Tibbets, Michael N.; Cabezas, L. Morris; Wurbs, Ralph A.Rapid population and economic growth in Texas is accompanied by increased needs for water supply and flood control. Depleting groundwater reserves are resulting in an increased reliance on surface water. The rising cost of fossil fuel during the 1970's has focused attention on increasing hydroelectric power generation. Instream flow needs for fish and wildlife habitat and maintenance of fresh water inflows to bays and estuaries have received increased attention in recent years. The climate of the state is characterized by extremes of floods and droughts. Reservoirs are necessary to control and utilize the highly variable streamflow. Due to a number of economic, environmental, institutional, and political factors, construction of additional new reservoir projects is much more difficult now than in the past. Consequently, optimizing the beneficial use of existing reservoirs is becoming increasingly more important. In addition to ever increasing water related needs, other factors affecting reservoir operation change over time as well. Watershed and flood plain conditions are dynamic. Construction of numerous small flood retarding dams by the Soil Conservation Service and other entities in the watersheds of major reservoirs have reduced flood inflows to the reservoirs. Construction of numerous small ponds for recreation or watering livestock have also decreased reservoir inflows and yields. Increased runoff caused by watershed urbanization is significantly contributing to flooding problems in certain locations. The existing flood control reservoirs were planned and designed based on the expectation of ever increasing intensification of flood plain land use. However, the National Flood Insurance Program has resulted in zoning and regulation of 100-year flood plains. With stringent flood plain management, susceptibility to flooding could actually decrease over time as existing activities choose to leave the flood plain and regulation prevents other activities from moving into the flood plain. Reservoir sedimentation reduces available storage capacity. Construction of additional reservoirs, as well as other related types of projects such as conveyance facilities, flood control levees and channel improvements, and electric power plants, affect the operation of existing reservoirs. Technological advancements in hydrologic data collection, streamflow forecasting, system modeling and analysis, and computer technology provide opportunities for refining operating policies. Reservoir storage capacities and operating policies are generally established prior to construction and tend to remain constant thereafter. However, public needs and objectives and numerous factors affecting reservoir effectiveness significantly change over time. The increasing necessity to use limited storage capacity as effectively as possible warrants periodic reevaluations of operating policies. Operating procedures should be responsive to changing needs and conditions. Reallocation of storage capacity between flood control and conservation purposes represents one general strategy for modifying operating policies in response to changing needs and conditions. Reservoir operation is based upon the conflicting objectives of maximizing the amount of water available for conservation purposes and maximizing the amount of empty space available for storing flood waters. Conservation purposes include municipal, industrial, and agricultural water supply, hydroelectric power, recreation, and instream flow maintenance. Common practice is to operate a reservoir only for conservation purposes or only for flood control or to designate a certain reservoir volume, or pool, for conservation purposes and a separate pool for flood control. The conservation and flood control pools in a multiple purpose reservoir are fixed by a designated top of conservation (bottom of flood control) pool elevation. Planning, design, and operating problems associated with flood control are handled separately from those associated with conservation. Institutional arrangements are also based on separating flood control and conservation purposes. Increasing needs for providing water for various uses and reducing flood damages necessitate that limited reservoir storage capacity be used as beneficially as possible. Consequently, consideration of the interactions and tradeoffs between conservation and flood control operations is becoming increasingly more important. The traditional analysis methods and practices followed in planning and design of reservoir projects and during real-time operations have not really addressed the tradeoffs and interactions between flood control and conservation purposes. In general, expanded analysis capabilities are needed for periodically reevaluating the operating policies of existing reservoir systems. A particular need in this regard is for improved methods for evaluating the tradeoffs involved in reallocating storage capacity between flood control and conservation purposes.Item Reservoir Operation in Texas(Texas Water Resources Institute, 1985-06) Wurbs, Ralph A.Effective management of its surface water resources is essential to the continued growth and prosperity of the state of Texas. Rapid population and economic growth combined with depleting ground water reserves are resulting in ever increasing demands being placed upon the surface water resources. The climate of the state is characterized by floods and droughts. Reservoirs are necessary to control and utilize the highly variable streamflow. Numerous reservoirs have been constructed to facilitate management of the surface water resources of the various river basins of the state. The operation of these essential water control facilities is examined in this report. Reservoir operation is viewed here from the perspective of deciding how much water to store and to release or withdraw for flood control and various conservation purposes. The report is intended to provide a comprehensive, indepth description of how reservoirs are operated in TexasItem Reservoir/River System Reliability Considering Water Rights and Water Quality(Texas Water Resources Institute, 1994-03) Dunn, David D.; Sanchez-Torres, Gerardo; Wurbs, Ralph A.Effective management of the highly variable water resources of a river basin requires an understanding of the amount of suitable quality water that can be provided under various conditions within institutional constraints. Although much research has been reported in the published literature regarding modeling reservoir system operations and evaluating water supply reliabilities, relatively little work has addressed integration of water rights and salinity considerations in comprehensive water availability studies. However, from a practical water management perspective, these are the controlling factors in many river basins in Texas and elsewhere. The study documented by this report provides expanded capabilities for modeling and analysis of reservoir/river system reliability, with a focus on institutional (water rights) and water quality (salinity) considerations. Population and economic growth combined with depleting ground water reserves are resulting in ever increasing demands on the surface water resources of Texas. Water rights and salinity represent two particularly important considerations in management and utilization of the surface water resources of the state. With the recent implementation of a prior appropriation permit system, water rights have become a key aspect of reservoir/river system management. Natural salt pollution is also a controlling constraint in utilization of the waters of a number of major river basins in Texas and neighboring states. Surface water law in Texas developed historically over several centuries. Claims have been recognized to water rights granted under Spanish, Mexican, Republic of Texas, and United States, as well as State of Texas, laws. Early water rights were granted based on various versions of the riparian doctrine. A prior appropriation system was later adopted and then modified. An essentially unmanageable system evolved, with various types of water rights existing simultaneously and with many rights being unrecorded. The Water Rights Adjudication Act of 1967 merged the riparian water rights into the prior appropriation system. The allocation of surface water now has been consolidated into a unified permit system. The water rights adjudication process required for transition to the permit system was initiated in 1968 and was completed in the late 1980s. About 7,700 active permits are now in effect for use of the waters of the 15 major river basins and eight coastal basins of the state. Applications for additional new permits or modifications to existing permits can be submitted to the Texas Natural Resource Conservation Commission at any time. Applications are approved only if unappropriated water is available, existing rights are not impaired, a beneficial use is contemplated, water conservation will be practiced, and the water use is not detrimental to the public welfare. Water quality in several major river basins in the Southwestern United States is seriously degraded by natural salt contamination. The salt, which consists largely of sodium chloride, originates from geologic formations underlying portions of the upper watersheds of the Arkansas, Canadian, Red, Brazos, Colorado, and Pecos Rivers in the states of Kansas, Colorado, Oklahoma, New Mexico, and Texas. Millions of years ago, this region was covered by a shallow inland sea. The salt-bearing geologic formations were formed by salts precipitated from evaporating sea water. Salt springs and seeps and salt flats in the upper portions of the river basins now contribute large salt loads to the rivers. The natural salt pollution significantly impacts water resources development and management. The Brazos River Basin provides a case study for the research. A water supply reliability study was performed for a system of 12 reservoirs owned and operated by the Brazos River Authority and U.S. Army Corps of Engineers. The evaluation of the water supply capabilities of the 12-reservoir system reflects the facts that: (1) over a thousand entities, owning about six hundred reservoirs, hold permits to use the waters of the Brazos River and its tributaries and (2) much of the streamflow is unsuitable for most beneficial uses much of the time due to excessively high salt concentrations. The Brazos River Basin illustrates a general situation which is characteristic of other major river basins as well. A significant need exists for improving modeling and analysis capabilities for performing comprehensive water availability studies. Reservoir/river system reliability analyses support planning studies and management decisions regarding (1) improvements in reservoir system operating policies, water rights allocations, and water supply contracts, (2) facility expansions and construction of new water supply projects, and (3) projects and strategies for dealing with salinity. Formulation and implementation of innovative management strategies for operating reservoir systems, allocating water between multiple uses and users, and minimizing the adverse impacts of natural salt pollution require that a river basin be treated as an integrated system.Item Water Rights Analysis Package (WRAP) Model Description and User's Manual(Texas Water Resources Institute, 1996-10) Dunn, David D.; Wurbs, Ralph A.The evolution of the Water Rights Analysis Package (WRAP) is outlined in the "Model Development Background" section of Chapter 1 of this report. The model was developed in conjunction with a series of university research projects sponsored by the Texas Water Resources Institute, U.S. Geological Survey, Brazos River Authority, Texas Advanced Technology Program, Texas Water Development Board, and Texas Natural Resource Conservation Commission. W. Brian Walls, David D. Dunn, Anil R. Yerramreddy, and Gerardo Sanchez-Torres addressed various aspects of model develop- ment and application in their thesis and dissertation research as graduate students in the Civil Engineering Department at Texas A&M University. The revised October 1996 as well as the original March 1993 editions of this report document a modeling package consisting of three computer programs called WRAP2, WRAP3, and TABLES. The October 1996 edition of the software and documentation reflect the following revisions to the March 1993 version. * A watershed flow option has been added to WRAP2 and WRAP3 to supplement the control point approach for defining the location of system components and inputting naturalized streamflows. Flows at water right locations are computed as a function of the flows at control points provided as input. A flexible methodology is incorporated in the model that allows streamflows at water rights sites to be expressed as a function of control point flows optionally using information ranging from simple drainage area ratios to more complex relationships. * Dimension limits were changed to increase the maximum number of control points from 50 to 200. The maximum number of water rights and reservoirs was decreased from 2,000 to 1,700. The new watershed flow option allows up to 200 water rights sites in addition to the control point locations. Any of the dimension limits can be easily changed in the future as needed for particular applications. * Minor revisions to program TABLES include adding means in most of the tables and refining several headings. * Numerous minor refinements were made throughout this report to update or clarify the presen- tation. * "Appendix G: Guidelines for Developing WRAP Input" is a new addition to the report.Item Water Rights Analysis Package (WRAP) Modeling System Reference Manual(Texas Water Resources Institute, 2003-08) Wurbs, Ralph A.The Texas Water Resources Institute (TWRI), and many other agencies and organizations, have worked with Ralph Wurbs over the years to develop WRAP (the Water Rights Analysis Package). The WRAP model simulates management of the water resources of a river basin, or multiple-basin region, under a priority-based water allocation system. The model facilitates assessment of hydrologic and institutional water availability/reliability for existing and proposed requirements for water use and management. Basin-wide impacts of water resources development projects and management strategies may be evaluated. The software package is generalized for application to any river/reservoir/use system, with input files being developed for the particular river basin of concern. The model is documented by reference and users manuals that may be downloaded from this site along with the software. WRAP is incorporated in the Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) System.Item Water Rights Analysis Package (WRAP) Modeling System Users Manual(Texas Water Resources Institute, 2005-04) Wurbs, Ralph A.Item Water Rights Analysis Package (WRAP) Reference Manual(Texas Water Resources Institute, 2003-03) Wurbs, Ralph A.The Texas Water Resources Institute (TWRI), and many other agencies and organizations, have worked with Ralph Wurbs over the years to develop WRAP (the Water Rights Analysis Package). The WRAP model simulates management of the water resources of a river basin, or multiple-basin region, under a priority-based water allocation system. The model facilitates assessment of hydrologic and institutional water availability/reliability for existing and proposed requirements for water use and management. Basin-wide impacts of water resources development projects and management strategies may be evaluated. The software package is generalized for application to any river/reservoir/use system, with input files being developed for the particular river basin of concern. The model is documented by reference and users manuals that may be downloaded from this site along with the software. WRAP is incorporated in the Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) System.Item Water Rights Analysis Package (WRAP) Users Manual(Texas Water Resources Institute, 2003-03) Wurbs, Ralph A.The Water Rights Analysis Package (WRAP) is documented by a Reference Manual and this Users Manual. The Reference Manual explains WRAP capabilities and methodologies. This Users Manual provides the operational logistics for applying the model. The Users Manual describes the organization of input and output files and the content and format of input records.Item The Water Rights Analysis Package Users Manual, Version 2.0(Texas Water Resources Institute, 2003-08) Wurbs, Ralph A.The Texas Water Resources Institute (TWRI), and many other agencies and organizations, have worked with Ralph Wurbs over the years to develop WRAP (the Water Rights Analysis Package). The WRAP model simulates management of the water resources of a river basin, or multiple-basin region, under a priority-based water allocation system. The model facilitates assessment of hydrologic and institutional water availability/reliability for existing and proposed requirements for water use and management. Basin-wide impacts of water resources development projects and management strategies may be evaluated. The software package is generalized for application to any river/reservoir/use system, with input files being developed for the particular river basin of concern. The model is documented by reference and users manuals that may be downloaded from this site along with the software. WRAP is incorporated in the Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) System.