Sensitivity of the Red River Basin Flood Protection System to Climate Variability and Change

An original modeling framework for assessment of climate variation and change impacts on the performance of complex flood protection system has been implemented in the evaluation of the impact of climate variability and change on the reliability, vulnerability and resiliency of the Red River Basin flood protection system (Manitoba, Canada). The modeling framework allows for an evaluation of different climate change scenarios generated by the global climate models. Temperature and precipitation are used as the main factors affecting flood flow generation. System dynamics modeling approach proved to be of great value in the development of system performance assessment model. The most important impact of climate variability and change on hydrologic processes is reflected in the change of flood patterns: flood starting time, peak value and timing. The results show increase in the annual precipitation and the annual streamflow volume in the Red River basin under the future climate change scenarios. Most of the floods generated using three different climate models had an earlier starting time and peak time. The assessment of the performance of Red River flood protection system is based on the flood flows, the capacity of flood control structures and failure flow levels at different locations in the basin. In the Assiniboine River Basin, higher reliabilities at downstream locations are obtained indicating that Shellmouth reservoir plays an important role in reducing downstream flooding. However, a different trend was identified in the Red River Basin. The study results show that flood protection capacity of the Red River infrastructure is sufficient under low reliability criteria but may not be sufficient under high reliability criteria.     

Selecting risk levels in chance-constrained reservoir operation modeling: A fuzzy set approach

Many modifications, extensions, discussions, and evaluations of chance-constrained reservoir operating models have been reported in the technical literature. Lack of economic data and the fact that the establishment of acceptable risk levels in these types of models involves a human factor with all its vagueness of perception, subjectivity, and attitudes may not permit proper application of either reliability or multiobjective programming approaches. This paper presents a unique methodology for handling a practical problem of selecting risk levels in chance-constrained reservoir operation modeling. The proposed methodology is based on fuzzy set theory. Two types of fuzzy sets are used in the formulation of the reservoir long-term planning model, one for constraints and one for the objective function. An iterative solution algorithm for deriving an optimal decision using fuzzy set operations and the chance-constrained approach is developed and presented. A practical application of the approach demonstrates the feasibility and efficiency of both the proposed approach and its iterative search procedure for selecting risk levels in chance-constrained reservoir modeling.     

The Value of Considering Autocorrelation Between Inflows in the Stochastic Planning of Water Resource Systems

Reliability programming formulations offer a family ofexplicit stochastic models for planning the operationof complex water resources systems. These models usecumulative probability distributions of the sum ofinflows to characterize their variability in theplanning period. Applicability of these models for avariety of problems has been limited, mainly due tothe assumption of independence between inflows indifferent time periods that leads to the derivation ofconservative operating policies. This paper presentsthree new approaches to overcome this limitation. Theperformance of the proposed approaches is demonstratedthrough comparison of the operating policies derivedfrom these approaches and the Independent Approach. Operational planning of the Manitoba Hydro energygeneration system, a predominantly hydro-based utilitycompany in Manitoba (Canada), is used as the case study.     

A Combinatorial Procedure to Determine the Full Range of Potential Operating Scenarios for a Dam System

Traditional dam safety assessment tends to place the focus on estimating the probabilities of failure for the system based on a few subjectively-chosen operating scenarios. The techniques used to assess these systems rely on linear chains of events and are incapable of considering component interactions, feedbacks and non-linear behaviour. This paper uses a systems approach to develop a new technique that puts possibilities first and is capable of generating an exhaustive list of potential component operating state scenarios for the system. The scenarios can then be simulated using a Monte-Carlo approach to determine a wide range of system behaviour (outcomes) for each scenario, taking into account component interactions and feedbacks. A component operating states database is presented where the system can be broken down into various levels of detail and the operating states and causal factors for each component can be defined. The Cartesian product of each operating state set is used to derive the full range of potential operating scenarios, with each scenario consisting of a single operating state for every component in the system. The list of scenarios can be used as an input to a simulation model which can then be run many times for each scenario, using Monte-Carlo inputs which vary the timing and severity of events as well as the inflows. The approach for automated scenario generation is demonstrated on a simple and complex representation of a hydropower system and the scenarios are generated and counted. Results show that increasing system complexity results in exponentially increasing numbers of potential operating scenarios, with the simple system having a total of 1.1?×?10⁶ operating states in comparison to the complex system which has 1.83?×?10²⁷. The approach presented in this paper (a) reduces the subjectivity associated with traditional dam safety assessments through automated scenario generation, and (b) improves the ability to understand component interaction and feedbacks by describing a Monte Carlo simulation approach which can be used for scenario simulation. By understanding how the system responds to the full range of potential operating conditions, dam owners and asset managers can make informed decisions relating to the improvement of operating strategies and implementation of system upgrades.

     

Integrated Reservoir Management System for Adaptation to Climate Change: The Nakdong River Basin in Korea

This study begins with the premise that current reservoir management systems do not take into account the potential effects of climate change on optimal performance. This study suggests an approach in which multi-purpose reservoirs can adapt to climate change using optimal rule curves developed by an integrated water resources management system. The system has three modules: the Weather Generator model, the Hydrological Model, and the Differential Evolution Optimization Model. Two general circulation models (GCMs) are selected as examples of both dry and wet conditions to generate future climate scenarios. This study is using the Nakdong River basin in Korea as a case study, where water supply is provided from the reservoir system. Three different climate change conditions (historic, wet and dry) are investigated through the compilation of six 60 years long scenarios. The optimal rule curves for three multi-purpose reservoirs in the basin are developed for each scenario. The results indicate that although the rule curve for large-size reservoir is less sensitive to climate change, medium or small-size reservoirs are very sensitive to those changes. We further conclude that the large reservoir should be used to release more water, while small or medium-size reservoirs should store inflow to mitigate severe drought damages in the basin.     

An Operational Model for Support of Integrated Watershed Management

This paper presents a computer simulation-based methodology for operational support of integrated water resources management. The methodology is based on the systems approach, and use of feedback to capture physical and socio-economic processes occurring within a watershed. The approach integrates well established simulation models of physical processes with simulation models that describe socio-economic processes. The proposed methodology is illustrated by the evaluation of risk and vulnerability to changing climatic and socio-economic conditions in the Upper Thames watershed (south-western Ontario, Canada).The model results indicate that flooding in the watershed will be more severe as a result of climate change, while low flows are expected to remain at their current level. The most significant socio-economic factor in the Upper Thames watershed is water availability, shown to become under climate change a limiting factor for future growth and development.     

Sensitivity of reservoir operation performance to climatic change

The potential impacts of changing climatic conditions on the operational performance of water resource systems was investigated in this paper. A multi-site streamflow generation model was used to synthesize potential monthly flow sequences reflecting two different sets of climatic conditions. The generated data were subsequently employed as input to a reservoir operation model that was used to determine the reservoir response to the inflow resulting from the implementation of the reservoir operating policy. The performance of an example reservoir system, the Shellmouth Reservoir located in the Canadian province of Manitoba, was evaluated and compared for the two sets of conditions. The operational performance was evaluated in terms of the reliability of the system for meeting the three purposes of the actual reservoir. The reservoir performance was determined to be sensitive to the inflow data. The results indicate that climatic change has potentially important implications for the operation of the example reservoir system.     

Analytical Support for Integrated Water Resources Management: A New Method for Addressing Spatial and Temporal Variability

This paper discusses the development of an analytical support system for implementation of the Integrated Water Resources Management (IWRM) process. The system integrates four analytical tools: (i) geographic information system; (ii) system dynamics simulation; (iii) agent-based model; and (iv) hydrologic simulation. The choice of tools is driven by their ability to (a) respond to the main requirements of the IWRM and (b) explicitly describe system behaviour as function of time and location in space. The system dynamics simulation captures temporal dynamics in an integrated feedback model that includes sectors representing physical and socioeconomic system components. Management policies established in the participatory decision making environment are easily investigated through the simulation of system behaviour. Agent-based model is used to analyze spatial dynamics of complex physical-social-economic-biologic system. The IWRM support system is tested using data from the Upper Thames River Watershed, Ontario, Canada, in collaboration with the Upper Thames River Conservation Authority.     

Two New Non-structural Measures for Sustainable Management of Floods

Abstract

Modern flood mitigation is increasingly non-structural. Well-established, traditional non-structural measures such as zoning, building codes, flood proofing, early detection and warning, emergency planning, flood insurance, etc., appear today as indispensable complements to structural engineering solutions. Advancement of computer sciences and communications provides an opportunity for further broadening of the context of non-structural flood mitigation. Two new concepts, a flood management virtual database and a flood management decision support system, are presented in the paper. Their benefits are demonstrated through the development of prototype systems for the Red River basin in Manitoba, Canada. First, it is shown that the Internet technology is mature enough to support the development of virtual database for a complex domain such as floodplain management. It is also quite clear that this mode of support has many advantages when compared to more traditional centralized database model. Secondly, we concluded that the decision support system approach provides an opportunity to meet the expressed needs of residents living in flood-prone areas for improvement in the flood management and a major change in the decision-making process. A decision support system is envisioned as a tool for analyzing alternative mitigation and recovery strategies. It is proposed in this work as a way of making flood management process more transparent and efficient in reducing future economic, environmental, and social flood damages.