Advancing the Unit Flood Response Approach for Urban Flood Management

Flooding is the most frequent natural disaster that causes significant, societal, economic, and environmental damage. The processes involved in flooding are shaped by spatial and temporal factors including weather patterns, topography and geomorphology. In urban setting, where landscapers are dynamic, land cover, green spaces, and drainage play a crucial role. Recognising flood source areas (FSAs) is pivotal for strategic flood risk management (FRM). Although FSA identification is not novel concept, recent advancements in flood modelling research, driven by technology and methodology improvements have extended beyond traditional methods. Emerging modelling approaches in FRM propose innovative methodologies for flood risk mitigation focusing on understanding and addressing flooding at its source. This thesis offers a review of current modelling approaches used to identify FSAs, specifically the Unit Flood Response (UFR) approach. The approach is a spatial prioritisation method for flood defences and mitigation. Traditionally, reliant on hydrological modelling and streamflow routing, this these instead uses rain-on-grid models (TUFLOW and HEC-RAS 2D) to assess the importance of model choice for the UFR approach for a catchment in the UK. The thesis further developed the UFR methodology by using a Hazard Index (HI) and Building Exposure Index (BEI) to show the significant differences between the model outputs, as well as emphasising on the computational costs associated with these methodologies. Additionally, recognising the important role of drainage systems in urban infrastructure, this thesis addresses the limited body of work available on drainage representation in flood models by introducing the Capacity Assessment Framework (CAF) to be used for drainage representation. By applying the CAF to assess and represent the drainage system in Leeds, the thesis draws a direct link between spatial prioritisation of flood defences and drainage system performance. The thesis introduces the application of the CAF outputs in flood models, demonstrating a more explicit representation of spatially varied drinage capacity. By comparing the national average removal rate (NARR) of 12 mm/hr with CAFderived rates, the significant of realistic drainage representation in flood models is highlighted. Lastly, the UFR approach coupled with 2D rain-on-grid modelling is used to investigate the impact of climate change and drainage representation in the Lin Dyke catchment. This approach considers three scenarios (Baseline, Baseline+Climate Change, and Baseline+Climate Change+Drainage) to establish hazard and building exposure indices. Results highlight the importance of incorporating climate change projections and drainage representation in the UFR methodology for a thorough urban flood risk assessment. In synthesis, this thesis investigates the multiple factors of flood risk management, offering insights and innovations across various dimensions. The Unit Flood Response (UFR) emerges as promising tools for identifying flood source areas (FSAs), emphasising the need for adaptive decision-making in flood risk management (FRM). Our investigation extends beyond affected areas, focusing on understanding, and addressing flooding at its source. Moreover, the introduction of the Capacity Assessment Framework (CAF) provides a novel methodology for representing drainage systems in flood models based on their realistic performance in urban environments. By incorporating realistic representations of spatially varied drainage capacities in flood models, this thesis highlightsthe importance of considering multiple factors in the assessment for effective urban flood risk management. As climate change and urban development exert increasing pressures, the findings in this thesis underscore the importance of integrating these factors into flood risk models to ensure resilience and relevance in the face of evolving challenge

Improving decision support system in identifying vulnerability rating and prioritizing the best interventions for sustainable watersheds in Pakistan, Nepal, and Sri Lanka

Quantification of watershed vulnerability rating and prioritization of the best watershed management intervention is always a challenge for multidisciplinary experts in developing consensus. Consequently, the lack of a decision support system (DSS) negatively affects the adoption of promising interventions leading to reduced watershed communities’ resilience to climate change. Therefore, a DSS has been developed to integrate local multi-disciplinary knowledge in identifying the watershed vulnerability ratings and prioritizing the best site-specific watershed management interventions. The DSS developed was applied to selected watersheds using 25 local experts each in Pakistan, Nepal, and Sri Lanka. The results showed the DSS is conveniently applicable and effective in developing consensus among multidisciplinary experts. The DSS recommended that the best interventions for the selected watersheds should primarily reduce the existing accelerated land and water degradation through engineering and biological actions, namely the control the rainwater run-off losses through appropriate harvesting systems and their subsequent efficient utilization for improving food security, climate change resilience and livelihood of vulnerable watershed communities. The DSS developed can be helpful in developing local adaptation plans and strengthening the policy support for promoting sustainable watersheds in Pakistan, Nepal, and Sri Lanka. However, the system needs further refinement through the incorporation of the design, specifications and costing of the interventions and making the data acquisition and analysis automatic using an online electronic system for quicker results and appropriate resource allocation for stimulated adoption.Quantification of watershed vulnerability rating and prioritization of the best watershed management intervention is always a challenge for multidisciplinary experts in developing consensus. Consequently, the lack of a decision support system (DSS) negatively affects the adoption of promising interventions leading to reduced watershed communities’ resilience to climate change. Therefore, a DSS has been developed to integrate local multi-disciplinary knowledge in identifying the watershed vulnerability ratings and prioritizing the best site-specific watershed management interventions. The DSS developed was applied to selected watersheds using 25 local experts in Pakistan, Nepal, and Sri Lanka. Results showed that DSS is conveniently applicable and effective in developing consensus among multidisciplinary experts. The DSS recommended that the best interventions for the selected watersheds should primarily reduce the existing accelerated land and water degradation through engineering and biological actions. These actions may include controlling the rainwater run-off losses through appropriate harvesting systems and their subsequent efficient utilization for improving food security, climate change resilience and livelihood of vulnerable watershed communities. The DSS developed can be helpful in developing local adaptation plans and strengthening the policy support for promoting sustainable watersheds in Pakistan, Nepal, and Sri Lanka. However, the system needs further refinement through the incorporation of the design, specifications and costing of the interventions and making the data acquisition and analysis automatic using an online electronic system for quicker results and appropriate resource allocation for stimulated adoption

HYDROLOGIC MODELING AT UNGAUGED LOCATIONS IN SUPPORT OF THE DEVELOPMENT OF A VULNERABILITY RANKING PROTOCOL SYSTEM FOR ROAD-STREAM CROSSING INFRASTRUCTURE

Recent tropical storms that have resulted in flood events with large economic impacts in the Northeastern US have catalyzed efforts to understand the complex interactions between human and natural systems. Specifically, the resilience of our transportation infrastructure to climate and the impact of our transportation systems on the aquatic environment are of significant interest on both the local and regional scales to state and federal agencies. It is important that new, innovative approaches be developed that consider both the robustness of our infrastructure today and its ability to cope with forecasted extremes due to climate change. Because few streams are gauged to record their flows, road-stream crossings are almost always designed without adequate knowledge of what floods flows that will occur in the future. Hydrologic predictions at these ungauged locations are difficult and few techniques exist that can accurately estimate extreme flows without long-term precipitation and streamflows records. Robust analysis using either statistical or physically based models within a multi-model framework is a useful approach in quantifying the degree of uncertainty and variability across models at these ungauged, road-stream crossing locations. This paper reviews background information associated with the development of a hydrologic vulnerability protocol system for road-stream crossings currently being piloted in the Deerfield River basin, focused primarily on predicting flows in ungauged basins and estimating flood flows for current and future climate scenarios. Finally, a framework for a decision support tool is discussed within the context of providing hydrologic flood predictions at road-stream crossings within an online interactive map interface

A review of modelling methodologies for flood source area (FSA) identification

Flooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises

Water Allocation Challenges in Rural River Basins: A Case Study from the Walawe River Basin, Sri Lanka

This dissertation evaluates the water allocation challenges in the rural river basins of the developing world, where demands are growing and the supply is limited. While many of these basins have yet to reach the state of closure, their water users are already experiencing water shortages. Agricultural crop production in rural river basins of the developing world plays a major role in ensuring food security. However, irrigation as the major water consumer in these basins has low water use efficiency. As water scarcity grows, the need to maximize economic gains by reallocating water to more efficient uses becomes important. Water allocation decisions must be made considering the social economic and environmental conditions of the developing world. The purpose of this dissertation is to identify water allocation strategies that satisfy the above conditions, in the example of the Walawe River basin in Sri Lanka. In this dissertation three manuscripts are presented. The first manuscript takes a broad view of the current water allocation situation. The second manuscript develops a methodology to analyze water allocation under a priority-based approach with the use of network flow simulation techniques. The third manuscript analyzes the water supply-demand situation in the basin under future climatic conditions. The major findings of this study suggest that: (1) while up to 44% of water is still available for use, seasonality of inflows, poor water management, physical infrastructure deficiencies, and other socio-economic factors contribute to the irrigation deficits in the Walawe basin; (2) prioritizing irrigation over hydropower generation increases supply reliability by 21% in the Walawe irrigation system IRR 1. The corresponding annual loss in power output in less than 0.5%. Prioritizing the left bank irrigation area in system IRR 2 increases the economic gains from crop yields by US $1 million annually; (3) an increase of water use efficiency between 30-50% in agriculture can mitigate all water deficits in agriculture, urban water supply and industrial sectors; (4) the predicted 25% increase of rainfall over the Walawe basin in the 2050\u27s allows for 43% increase in hydropower generation (with changes to power generation mode) and 3-16 % reduction in irrigation requirements; (5) network flow simulation techniques can be successfully used to evaluate different demand management strategies and improvements to the priority-based water allocation method

On the application of dynamical measures of hydrologic response to prediction and similarity assessment in watersheds

The Prediction in Ungauged Basins (PUB) initiative set out to improve the understanding of hydrological processes with an aim of improving hydrologic models for application in ungauged basins. With a majority of basins around the world essentially ungauged, this suggests the need to shift from calibration-based models that rely on observed streamflow data to models based on process understanding. This is especially important in natural infrastructure planning projects such as investments in the conservation of wetlands across the watershed, where the lack of streamflow data hinders the quantification of their benefits (such as flood attenuation), resulting in a difficulty in prioritization. This research sought to contribute to this growing body of literature by (a) developing visual tools and metrics for assessing flow dynamics and flood attenuation benefits of wetlands in relation to their position in the watershed, (b) examining distribution-based topographic metrics in regard to their efficacy in predicting hydrologic response and providing a methodology for examining other metrics in future studies, (c) building robust functional forms for two important catchment metrics: the width function and hypsometric curve, and (d) devising a hierarchical clustering approach to assess hydrological similarity and find analogous basins that is computationally efficient and has a potential for large-scale applications. Taken together, this study paves the way toward an analytical formulation of the geomorphological instantaneous unit hydrograph (GIUH) that can be used to assess the hydrological behavior in ungauged or data-scarce basins

Science and innovation for catchment management: report of scientific workshop May 2019

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This report represents an overview of the participation, activities and conclusions at a Scientific Workshop, held at Warwick Conferences at the University of Warwick, UK from 8th to 10th May, 2019. The workshop was convened by the India-UK Water Centre and led by Mr Ant Parsons (ALP Synergy Ltd) and Dr Kapil Gupta (IIT Bombay). The three-day workshop aimed to explore and build on existing knowledge and research to enhance collaboration and identify pathways to impact (including relevant NERC-MoES Science), identify gaps in research and innovation that are constraining sustainable catchment management, explore innovative approaches to monitoring and management, and consider the potential for SMART Rivers as part of integrated catchment management. The aims of the workshop were met by bringing together early career researchers, seasoned professors and experienced professionals from India and the UK, who covered a wide range of topics across the themes of climate, water quality, water quantity, and land and catchment management. The following report outlines some common challenges, cross-cutting themes and activities required for improving catchment management, potential solutions to catchment management and shares some of the ideas for new collaborative projects that were developed. The report is intended for the workshop participants, India-UK Water Centre members and stakeholders

Adaptation strategies of dam safety management to new climate change scenarios informed by risk indicators

Tesis por compendio[ES] Las grandes presas, así como los diques de protección, son infraestructuras críticas cuyo fallo puede conllevar importantes consecuencias económicas y sociales. Tradicionalmente, la gestión del riesgo y la definición de estrategias de adaptación en la toma de decisiones han asumido la invariabilidad de las condiciones climáticas, incluida la persistencia de patrones históricos de variabilidad natural y la frecuencia de eventos extremos. Sin embargo, se espera que el cambio climático afecte de forma importante a los sistemas hídricos y comprometa la seguridad de las presas, lo que puede acarrear posibles impactos negativos en términos de costes económicos, sociales y ambientales. Los propietarios y operadores de presas deben por tanto adaptar sus estrategias de gestión y adaptación a medio y largo plazo a los nuevos escenarios climáticos. En la presente tesis se ha desarrollado una metodología integral para incorporar los impactos del cambio climático en la gestión de la seguridad de presas y en el apoyo a la toma de decisiones. El objetivo es plantear estrategias de adaptación que incorporen la variabilidad de los futuros riesgos, así como la incertidumbre asociada a los nuevos escenarios climáticos. El impacto del cambio climático en la seguridad de presas se ha estructurado utilizando modelos de riesgo y mediante una revisión bibliográfica interdisciplinaria sobre sus potenciales efectos. Esto ha permitido establecer un enfoque dependiente del tiempo que incorpore la evolución futura del riesgo, para lo cual se ha definido un nuevo indicador que evalúa cuantitativamente la eficiencia a largo plazo de las medidas de reducción de riesgo. Además, para integrar la incertidumbre de los escenarios futuros en la toma de decisiones, la metodología propone una estrategia robusta que permite establecer secuencias optimizadas de implementación de medidas correctoras para la adaptación al cambio climático. A pesar de las dificultades para asignar probabilidades a eventos específicos, esta metodología permite un análisis sistemático y objetivo, reduciendo considerablemente la subjetividad. Esta metodología se ha aplicado al caso real de una presa española susceptible a los efectos del cambio climático. El análisis se centra en el escenario hidrológico, donde las avenidas son la principal carga a la que está sometida la presa. Respecto de análisis previos de la presa, los resultados obtenidos proporcionan nueva y valiosa información sobre la evolución de los riesgos futuros y sobre cómo abordarlos. En general, se espera un aumento del riesgo con el tiempo; esto ha llevado a plantear nuevas medidas de adaptación que no están justificadas en la situación actual. Esta es la primera aplicación documentada de un análisis exhaustivo de los impactos del cambio climático sobre el riesgo de rotura de una presa que sirve como marco de referencia para la definición de estrategias de adaptación a largo plazo y la evaluación de su eficiencia.[CAT] Les grans preses, així com els dics de protecció, són infraestructures crítiques que si fallen poden produir importants conseqüències econòmiques i socials. Tradicionalment, la gestió del risc i la definició d'estratègies d'adaptació en la presa de decisions han assumit la invariabilitat de les condicions climàtiques, inclosa la persistència de patrons històrics de variabilitat natural i la probabilitat d'esdeveniments extrems. No obstant això, s'espera que el canvi climàtic afecte de manera important als sistemes hídrics i comprometi la seguretat de les preses, la qual cosa pot implicar possibles impactes negatius en termes de costos econòmics, socials i ambientals. Els propietaris i operadors de preses deuen per tant adaptar les seues estratègies de gestió i adaptació a mitjà i llarg termini als nous escenaris climàtics. En la present tesi s'ha desenvolupat una metodologia integral per a incorporar els impactes del canvi climàtic en la gestió de la seguretat de preses i en el suport a la presa de decisions. L'objectiu és plantejar estratègies d'adaptació que incorporen la variabilitat dels futurs riscos, així com la incertesa associada als nous escenaris climàtics. L'impacte del canvi climàtic en la seguretat de preses s'ha estructurat utilitzant models de risc i mitjançant una revisió bibliogràfica interdisciplinària sobre els seus potencials efectes. Això ha permès establir un enfocament dependent del temps que incorpori l'evolució futura del risc, per a això s'ha definit un nou indicador que avalua quantitativament l'eficiència a llarg termini de les mesures de reducció de risc. A més, per a integrar la incertesa dels escenaris futurs en la presa de decisions, la metodologia proposa una estratègia robusta que permet establir seqüències optimitzades d'implementació de mesures correctores per a l'adaptació al canvi climàtic. A pesar de les dificultats per a assignar probabilitats a esdeveniments específics, esta metodologia permet una anàlisi sistemàtica i objectiva, reduint considerablement la subjectivitat. Aquesta metodologia s'ha aplicat al cas real d'una presa espanyola susceptible a l'efecte del canvi climàtic. L'anàlisi se centra en l'escenari hidrològic, on les avingudes són la principal càrrega a la qual està sotmesa la presa. Respecte d'anàlisis prèvies de la presa, els resultats obtinguts proporcionen nova i valuosa informació sobre l'evolució dels riscos futurs i sobre com abordar-los. En general, s'espera un augment del risc amb el temps; això ha portat a plantejar noves mesures d'adaptació que no estarien justificades en la situació actual. Aquesta és la primera aplicació documentada d'una anàlisi exhaustiva dels impactes del canvi climàtic sobre el risc de trencament d'una presa que serveix com a marc de referència per a la definició d'estratègies d'adaptació a llarg termini i l'avaluació de la seua eficiencia.[EN] Large dams as well as protective dikes and levees are critical infrastructures whose failure has major economic and social consequences. Risk assessment approaches and decision-making strategies have traditionally assumed the stationarity of climatic conditions, including the persistence of historical patterns of natural variability and the likelihood of extreme events. However, climate change has a major impact on the world's water systems and is endangering dam safety, leading to potentially damaging impacts in terms of economic, social and environmental costs. Owners and operators of dams must adapt their mid- and long-term management and adaptation strategies to new climate scenarios. This thesis proposes a comprehensive approach to incorporate climate change impacts on dam safety management and decision-making support. The goal is to design adaptation strategies that incorporate the non-stationarity of future risks as well as the uncertainties associated with new climate scenarios. Based on an interdisciplinary review of the state-of-the-art research on its potential effects, the global impact of climate change on dam safety is structured using risk models. This allows a time-dependent approach to be established to consider the potential evolution of risk with time. Consequently, a new indicator is defined to support the quantitative assessment of the long-term efficiency of risk reduction measures. Additionally, in order to integrate the uncertainty of future scenarios, the approach is enhanced with a robust decision-making strategy that helps establish the consensus sequence of measures to be implemented for climate change adaptation. Despite the difficulties to allocate probabilities to specific events, such framework allows for a systematic and objective analysis, reducing considerably the subjectivity. Such a methodology is applied to a real case study of a Spanish dam subjected to the effects of climate change. The analysis focus on hydrological scenarios, where floods are the main load to which the dam is subjected. The results provide valuable new information with respect to the previously existing analysis of the dam regarding the evolution of future risks and how to cope with it. In general, risks are expected to increase with time and, as a result, new adaptation measures that are not justifiable for the present situation are recommended. This is the first documented application of a comprehensive analysis of climate change impacts on dam failure risk and serves as a reference benchmark for the definition of long-term adaptation strategies and the evaluation of their efficiency.Fluixá Sanmartín, J. (2020). Adaptation strategies of dam safety management to new climate change scenarios informed by risk indicators [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/157634TESISCompendi

A Morphometric Analysis of Ravi River Basin in Himachal Pradesh

Morphometric analysis of Ravi River basin in Himachal Pradesh is located in Kangra and Chamba Districts of State of Himachal Pradesh. Analysis of various morphometric attributes are done to understand the geomorphologic evolutionary stages of this basin. From the analysis it wasinferred that this basin in a matured stage. The morphometric analysis is carried out through measurement of linear, aerial and relief aspects of the basin and slope contribution to understand the run-off characteristics of the area and potentiality of basin corrosion. The measurement of various morphometric parameters namely stream order, stream length (Lu), mean stream length, bifurcation ratio, mean bifurcation ratio, drainage density, stream frequency and elongation ratio has been carried out. Structural and geomorphological features control the directions of flow of the tributaries. Drainage morphometric analysis gives overall view of the terrain information like hydrological, lithological, slope, relief, variations in the watershed, ground water recharge, porosity, soil characteristics, flood peak, rock resistant, permeability and runoff intensity and is useful for geological, hydrological, ground water prospects, civil engineering and environmental studies