Assessment of the Impact of Climate Variability and Change on the Reliability, Resiliency and Vulnerability of Complex Flood Protection Systems

An original modeling framework (DYHAM) for assessment of climate variation and change impacts on the performance of complex flood protection system has been developed and tested using the Red River basin (Manitoba) as a case study. Modeling framework allows for 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. Floods in the Red River basin generally occur in spring when the increase in temperature initiates snowmelt that usually coincides with heavy rain. In this study more than 90% of floods (at Shellmouth reservoir on the Assiniboine River and at Ste. Agathe on the Red River) generated using three different climate models started earlier in March and April. We conclude that the increase in temperature from climate variation and change results in an earlier flood starting time in the Red River basin. The DYHAM 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.https://ir.lib.uwo.ca/wrrr/1000/thumbnail.jp

A Spatial Fuzzy Compromise Approach for Flood Disaster Management

Natural disasters affect regions with different intensity and produce damages that vary in space. Topographical features of the region; location of properties that may be exposed to the peril; level of exposure; impact of different mitigation measures; are all variables with considerable spatial variability. A new method for evaluation of disaster impacts has been presented in this report that takes into consideration spatial variability of variables involved and associated uncertainty. Flood management has been used to illustrate the utility of proposed approach. Floodplain management is a spatial problem. Representation of flood damage mitigation alternatives and objectives in space provides a better insight into the management problem and its characteristics. Protection of a region from floods can be achieved through various structural and non-structural measures. Comparison of different measures and evaluation of their impacts is based on the multiple criteria. If they are described spatially, decision-making problem can be conceptualized as spatial multi criteria decision-making (MCDM). Tkach and Simonovic (1997) introduced spatial Compromise Programming (SPC) technique to account for spatial variability in flood management. Some of the criteria and preferences of the stakeholders involved with flood management are subject to uncertainty that may originate in the data, knowledge of the domain or our ability to adequately describe the decision problem. The main characteristic of flood management is the existence of objective and subjective uncertainty. Fuzzy set theory has been successfully used to address both, objective and subjective uncertainty. Bender and Simonovic (2000) incorporated vagueness and imprecision as sources of uncertainty into multi criteria decision-making in water resources. In this report a new technique named Spatial Fuzzy Compromise Programming (SFCP) has been developed to enhance our ability to address the issues related to uncertainties in spatial environment. A general fuzzy compromise programming technique, when made 2 spatially distributed, proved to be a powerful and flexible addition to the list of techniques available for decision making where multiple criteria are used to judge multiple alternatives. All uncertain variables (subjective and objective) are modeled by way of fuzzy sets. In the present study, fuzzy measures have been introduced to spatial multi criteria decision-making in the GIS environment in order to account for uncertainties. Through a case study of the Red River floodplain near the City of St. Adolphe in Manitoba, Canada, it has been illustrated that the new technique provides measurable improvement in flood management. Final results in the form of maps that shown spatial distribution of the impacts of mitigation measures on the region can be of great value to insurance industry.https://ir.lib.uwo.ca/wrrr/1004/thumbnail.jp

Role of Remote Sensing in Disaster Management

The objective of this report is to review the existing satellites monitoring Earth’s resources and natural disasters. Each satellite has different repeat pass frequency and spatial resolution (unless it belongs to the same series of satellites for the purpose of continuation of data flow with same specifications). Similarly, different satellites have different types of sensors on-board, such as, panchromatic, multispectral, infrared and thermal. All these sensors have applications in disaster mitigation, though depending on the electromagnetic characteristics of the objects on Earth and the nature of disaster itself. With a review of the satellites in orbit and their sensors the present work provides an insight to suitability of satellites and sensors to different natural disasters. For example, thermal sensors capture fire hazards, infrared sensors are more suitable for floods and microwave sensors can record soil moisture. Several kinds of disasters, such as, earthquake, volcano, tsunami, forest fire, hurricane and floods are considered for the purpose of disaster mitigation studies in this report. However, flood phenomenon has been emphasized upon in this study with more detailed account of remote sensing and GIS (Geographic Information Systems) applicability. Examples of flood forecasting and flood mapping presented in this report illustrate the capability of remote sensing and GIS technology in delineating flood risk areas and assessing the damages after the flood recedes. With the help of a case study of the Upper Thames River watershed the use of remote sensing and GIS has been illustrated for better understanding. The case study enables the professionals and planning authorities to realize the impact of urbanization on river flows. As the urban sprawl increases with the increase of population, the rainfall and snow melt reaches the river channels at a faster rate with higher intensity. In other words it can be inferred that through careful land use planning flood disasters can be mitigated.https://ir.lib.uwo.ca/wrrr/1002/thumbnail.jp

Inverse Drought Risk Modelling of the Upper Thames River Basin

This report aims to present an alternate approach to climate change impact mod- elling of water resources. The focus of the project is on the analysis of existing water resources management guidelines specifically targeting critical hydrologic events (ex- treme droughts in this case). The critical hydrologic events are converted to their corresponding meteorologic conditions via use of an appropriate hydrologic model (continuous based hydrologic model for drought analysis). The local climatic signal is generated by use of a non-parametric weather generator linked to outputs from a global circulation model for three climate scenarios, and their corresponding fre- quency curves generated. Then, a critical hydrologic event of interest is selected, its corresponding meteorological condition obtained, and its frequency of occurrence for each climate scenario determined. It is noted that all climate change scenarios showed less frequent occurrence of extreme droughts. However, potentially severe droughts are still possible (with a chance of 1 in 10 any given year, sometime less) in the basin; this coupled with the fact that drought damage assessments are non existent in the basin suggests that new or improved drought management guidelines should be investigated. Based on the analysis presented, recommendations are made for future work to in- clude: (i) drought impact studies (where impacts to agriculture, recreation, wetlands, reservoir operation, ground water withdrawal and streamflow quality are assessed); (ii) definition of local drought triggers (including guidelines on subwatershed scale, as well as monitoring how drought triggers change over time); (iii) water quality man- agement (setting in place practises that enhance water quality over short and long term); (iv) education programs (to bring up to date knowledge in science to all who stand to be adversely impacted by drought).https://ir.lib.uwo.ca/wrrr/1015/thumbnail.jp

City of London: Vulnerability of Infrastructure to Climate Change. Background Report #2: Hydraulic Modeling and Floodplain Mapping

The main objective of the research project currently under way is to provide an engineering assessment of the vulnerability of London’s public infrastructure under projected rates of climate change with special emphasis on flooding. An original systematic procedure is used to gather and examine available data in order to develop an understanding of the relevant climatic effects and their interaction with municipal infrastructure. Assessment of climate change impacts on municipal infrastructure requires floodplain maps and inundation that will correspond to examined climate change scenarios. This report presents the results of hydraulic analyses used in floodplain mapping under changing climate. Combined, climate and hydrologic modeling, were used to generate input flow data for hydraulic modelling. Standard computer software HEC-RAS is used for hydraulic computation of water elevation. The existing HEC-RAS models of the Upper Thames River basin are not georeferenced and therefore they cannot be used for hydraulic modeling under climate change. Consequently, it was necessary to develop new HEC-RAS models for the rivers and creeks of London that were considered in this project. Geometric input data for new HEC-RAS models were created using HEC-GeoRAS software, which is an extension of ArcGIS computer package for spatial analysis. In the preprocessing phase the HEC-GeoRAS is used to create a digital terrain model from the contour lines shape file provided by the city of London. In the next step the following geometric data layers were generated: river center line, bank lines, flowpaths, cross sections, and bridges. Required attributes were assigned to each of the layers. In the last step of the pre-processing stage the input file for the HEC-RAS hydraulic analysis was prepared. The hydraulic analysis starts with the geometric data import, followed with the preparation of the hydraulic structures data and flow data. A very detailed quality control was performed on the cross sections data generated during the pre-processing phase. The roughness coefficient values were determined using the existing HEC-RAS models and aerial photography of the basin. Data on bridges, taken from the existing models and drawings were integrated with the rest of the data. Two climate scenarios (historic and wet) developed by climate and hydrologic modeling (Eum and Simonovic, 2009) were used and water surface elevation profiles were calculated for 100- and 250- year return periods. The computation results were used to assemble the HEC-RAS GIS export file for floodplain mapping. The Arc Map software package was used to create water surface GIS layer. Overlaying this layer with the terrain provided for calculation of floodplain boundaries and inundation depths. The floodplain maps generated using this process are used in vulnerability assessments of London’s public infrastructure to climate change currently in progress. The results of water surface profile computations are presented in tabular form for the 250- year flood under historic and wet climate scenarios. The final floodplain maps along Main Thames for both scenarios show minor deviation of the floodplain boundaries when compared with the existing floodplain lines. However, the water depth difference is up to 50 cm. The area upstream from the culvert on Pottersburg Creek (close to the intersection of Trafalgar St. and Clarke St.) is identified as critical due to the high extent of flooding. The flooding at this location is caused by insufficient culvert opening that creates a backwater effect. Areas of special concern are identified where the floodplain mapping results are not sufficiently accurate due to inaccuracies in the contour lines. The main recommendation based on the work presented in this report is that new georeferenced cross sections should be surveyed in order to increase the accuracy of the floodplain mapping process. The hydraulic analyses should be repeated with more accurate input data and the resulting floodplain maps should be revised accordingly.https://ir.lib.uwo.ca/wrrr/1031/thumbnail.jp

NDM-515: AN ORIGINAL MODEL OF INFRASTRUCTURE SYSTEM RESILIENCE

Infrastructure systems of transportation, water supply, telecommunications, power supply, etc. are not isolated but highly interconnected and mutually coupled. Infrastructure interdependences can increase system vulnerability and produce cascading failures at the regional or national scales. Taking the advantage of network theory structure analysis, this paper models street, water supply network, power grid and information infrastructure as network layers that are integrated into a multilayer network. The infrastructure interdependences are detailed using five basic dependence patterns of network fundamental elements. Definitions of dynamic cascading failures and recovery mechanisms of infrastructure systems are also established. The main focus of the paper is introduction of a new infrastructure network resilience measure capable of addressing infrastructure system as well as network component (layer) interdependences. The new measure is based on infrastructure network performance, proactive infrastructure network resistance capacity and reactive infrastructure network recovery capacity. With three resilience features and corresponding network properties develops paper, this the of dynamic space new quantitative measure -time resilience and a resilience simulation model resilience and network properties three dimensions of use for infrastructure network assessments. The resilience model is applicable to any type of infrastructure and its application can improve the infrastructure planning, design and maintenance decision making

A General Overview of Multi-objective Multiple-participant Decision Making for Flood Management

Decision-making problems in water resources are often associated with multiple objectives and multiple stakeholders. To enable more effective and acceptable decision outcome, it is required that more participation is ensured in the decision making process. This is particularly relevant for flood management problems where the number of stakeholders could be very large. Although application of multi-objective decision-making tools in water resources is very wide, application with the consideration of multiple stakeholders is much more limited. The solution methodologies adapted for multi-objective multi-participant decision problems are generally based on aggregation of decisions obtained for individual decision makers. This approach seems somewhat inadequate when the number of stakeholders is very large, as often is the case in flood management. The present study has been performed to have an overview of existing solution methodologies for multi-objective decision making approaches in water resources. Decision making by single and multiple stakeholders has been considered under both deterministic and uncertain conditions. It has been found that the use of fuzzy set theory to represent various uncertainties associated with decision making situations under multi-objective multiple-participant environment is very promising. Coupled with multi-objective methods (e. g. compromise programming and goal programming), fuzzy approach has also the ability to support group decisions, to reflect collective opinions and conflicting judgments.https://ir.lib.uwo.ca/wrrr/1003/thumbnail.jp