City Flood Research Articles

Factors responsible for temporal and spatial variations in water and sediment discharge in Ramganga River, Ganga Basin, India

The Ramganga River flows from the mountainous regions of Kumaon Himalayas, through the forests of Jim Corbett National Park and the Ganga flood plains. It is the first major tributary of the Ganga River, carrying high sediment load causing frequent floods in major cities of Uttar Pradesh. The water discharge of the river is controlled by glacial melt as well as precipitation, making it a perennial river. This study is on the temporal and spatial variation of water discharge and sediment flux of the Ramganga River and identifies the factors which control them. In this study, 84 samples were collected from different locations over the 642 km stretch of the river and its major tributaries to observe the temporal and spatial variation of suspended matter in river water. In addition, daily water flow and sediment concentration data of two locations, e.g. Bareilly and Dabri, for a duration of 10 years were used to understand the variation in those parameters over an extended time period. An attempt was also made to relate meandering to the change in water discharge and sediment flux in the Ganga flood plains. Human activities also contribute to the sediment concentration. The results of this study showed that a significant amount of water flow and sediment flux (>75 %) were attributed to the monsoon months. However, in 2009, the results were not similar to other years, probably because of low rainfall due to the occurrence of an El Nino.

Real-Time Assessment of the 16 September 2015 Chile Tsunami and Implications for Near-Field Forecast

The magnitude 8.3 earthquake in central Chile on 16 September 2015 and the resulting tsunami severely affected the region, with 15 deaths (ONEMI in Monitoreo por sismo de mayor intensidad. (In Spanish) [Available at: http://www.onemi.cl/alerta/se-declara-alerta-roja-por-sismo-de-mayor-intensidad-y-alarma-de-tsunami/], 2015), over one million evacuated, and flooding in nearby coastal cities. We present our real-time assessment of the 2015 Chile tsunami using the Short-term Inundation Forecasting for Tsunamis system, and post-event analyses with local community models in Chile. We evaluate three real-time tsunami sources, which were inverted at the time that the first quarter-, half-, and full-wave passed the first tsunameter (DART 32402, located approximately 580 km north–northwest of the epicenter), respectively. Measurement comparisons from 26 deep-ocean tsunameters and 38 coastal tide stations show that good model accuracies are achieved for all three sources, particularly for the local sites that recorded the most destructive waves. The study highlights the forecast speed, time and accuracy dependence, and their implications for the local forecast capability. Our analyses suggest that the tsunami’s main origination area is about 100–200 km long and 100 km wide, to the north of the earthquake epicenter along the trench and the total estimated tsunami wave energy is 7.9 × 1013 J (with 13 % uncertainty). The study provides important guidelines for the earliest reliable estimate of tsunami energy and local forecasts. They can be obtained with the first quarter-wave of tsunameter recording. These results are also confirmed by a forecast analysis of the 2011 Japan tsunami. Furthermore, we find that the first half-wave tsunameter data are sufficient to accurately forecast the 2015 Chile tsunami, due to the specific orientation between the nearest tsunameter and the source. The study also suggests expanding the operational use of the local community models in real time, and demonstrates the applicability of the model results for ‘‘all-clear’’ evaluations, search and rescue operations, and near-real-time mitigation planning in both near and far fields.

Cameroonian Urban Floodwater Retaliations on Human Activity and Infrastructural Developments in Channel Flood Ways of Kumba

In Cameroonian cities, floods from solid pollutant barriers constitute environmental hazards of new distinct dimension, nature and characteristics. This study examines geographical settings provoking floods in cities and the way it affects the population. It suggests appropriate policy mitigation options. Primary and secondary data collected through fieldwork and documentary sources were treated. Findings show that national and local rules and legislation are weakly applied exposing urban natural floodway to varied forms of human colonisation activities. These urban stream flood ways that ought to be downstream water evacuation role players reversed into inhabited neighbourhoods of diverted water. Human activities and infrastructural urban inputs that unconsciously imposed directional dictates unto urban stream flow have become self-made victims of wicked egocentrism over urban stream channels. As nature is permanently in a state of dynamic re-equilibration the urban stream waters have in retaliation taught its trouble givers a disproportionately unequal negative response in enormous fatalities for the humans who dare to resist its floods and abandonment for those who have been repeatedly humbled by its floods. The response from this no man’s land of aborted human conquest requires comprehensive and multidimensional environmental management in stream-bordered urban built.

Surface Water Management in Ghana

If adequate measures are not taken to protect the water bodies in Ghana, the rivers will dry up and those left will be highly polluted and the country will have to import drinking water from the neighbouring countries and from abroad for human consumption. Also, lots of lives and property would be lost through flooding in most cities in every rainy season if certain habits like building on water ways and dumping of rubbish into drains are not discouraged.

Flood Modeling and Simulation using iRIC: A Case Study of Kabul City

In Afghanistan, floods are common and measures must be taken to protect people and property from damage. There is, however, a lack of detailed observations and research on this subject in this area. Therefore, flood simulation models are needed to identify flood-prone areas. In this study, International River Interface Cooperative (iRIC) program that is river flow and riverbed variation analysis software with several solvers has been used. Nays2DFlood solver that simulates 2dimenstional plane flow has applied to a past flood in Kabul city. River discharge from two inflow points and averaged precipitation from three rain gauges at the time of flooding given as input to the model including DEM (Digital Elevation Model) data. The iRIC was confirmed as a 90-m grid digital elevation model to determine the position of streamlines correctly. However, the highest flood depth was overestimated because the 90-m grids were too coarse to detect the slight slope of the riverbed in some areas. Then the elevation of the riverbed modified using data acquired from Google Earth, and the simulation results improved. Moreover, it was found that river water rather than rainfall was the main cause of the flooding.

余姚城北圩区布置及排涝泵站规模研究

余姚市遭遇2013年“菲特”台风特大洪灾后，为提高中心城区防洪排涝能力，分片实施中心城区围圩电排工程，但在规划方案制定过程中，由于未能充分考虑本区域的历史排水习惯，以及协调好圩区建设和城市建设的矛盾，致使规划方案未能全面保护受灾区域，并导致工程实施困难。本次研究针对滨海城市感潮河网地区，建立流域洪水模拟数学模型，从保护对象的完整性、工程实施的可行性以及工程实施的防洪排涝效益三个角度出发，对余姚城北圩区布置及排涝泵站规模进行优化调整，最终选取在工程可行性、城市景观、防汛调度、工程投资等方面均较优的方案作为城北圩区布置推荐方案，确保余姚城区防洪排涝工程建设的顺利进行和中心城区的防洪排涝安全。 In order to improve the ability of the central city flood control and drainage after “Fitow” typhoon in Oc-tober, 2013, the plan of slice implementation of urban district pumping stations was suggested in the Yuyao City. Since it did not consider the regional history of drainage conventions and coordinate the contradiction of water conservancy and urban construction, the plan is failed to fully protect the affected area which leads very difficult for project implementation. This research takes the coastal tidal river network area as example and establishes a flood simulation model to improve the polder area layout and drainage pumping station scale in the north district of Yuyao city. From the implementation of protecting integrity, engineering feasibility, flood control and drainage efficiency, the polder area layout scheme is ultimately selected by considering urban landscape and project investment factors, which the flood con-trol and drainage engineering would be constructed smoothly in the Yuyao city.

Back to the future: assessing the damage of 2004 Dhaka flood in the 2050 urban environment

AbstractPlanning to make a city flood resilient needs proper assessment of future conditions. Urban growth models are being used as a planning tool for city development. Within the project Collaborative Research in Flood Resilience in Urban Areas (CORFU), flood management strategies suitable for cities with varied geographic and socio‐economic conditions have been developed. In the paper, we adopted urban growth model to project the possible future conditions of Dhaka City, the rapidly developing capital of Bangladesh. Bangladesh lies in the delta of the Himalayan Mountain range and experiences frequent flooding. In 2004 an extreme nationwide flood event occurred, which caused major damage to Dhaka City. If the same event were to occur in 2050, it can be expected that the damage would increase significantly. Through the application of the urban growth, hydraulic and damage assessment models, we were able to determine the damage that can be expected to happen in 2050. The paper also describes the key factors that are important to determine this impact and the associated uncertainties.

Coastal infrastructure: a typology for the next century of adaptation to sea‐level rise

Categorizing the choices in coastal infrastructure that are available to policy makers will allow for comparisons of their potential impacts on ecosystems and of their value in preparation for long‐term sea‐level rise. Although similar approaches have been described elsewhere in different policy contexts, this article focuses on evaluating physical infrastructure types – including hybrid structures that combine landforms with concrete and steel elements –based on historical differences in engineering practices. Such structures can be optimized for different phases of coastal adaptation and can provide multiple benefits (eg supporting ecosystems as well as minimizing flooding in coastal cities). Key factors in a geomorphological, ecological, and land‐use context must be taken into account when selecting various infrastructure strategies, to ensure that they function as intended. The San Francisco Bay region provides an example of how this typology can be applied to help policy makers choose more successful strategies as coastal areas plan for sea‐level rise.

City Blueprints: baseline assessments of water management and climate change in 45 cities

Climate change and urbanization are among the most significant trends of the twenty-first century, affecting global natural resources such as water, economic development and human well-being. The growth of the world population will be absorbed by the cities. The necessity of cities adapting to these trends calls for radical changes in urban water management. In this paper, baseline assessments, i.e., City Blueprints, have been carried out for 45 municipalities and regions in 27 countries, mainly in Europe. The assessments showed that cities vary considerably with regard to their water management. This is also captured in the Blue City Index® (BCI), the arithmetic mean of 24 indicators comprising the City Blueprint®. Theoretically, the BCI has a minimum score of 0 and a maximum score of 10. The actual BCIs in the 45 cities and regions varied from 3.5 (Kilamba Kiaxi in Angola) to 8.5 (Helsingborg in Sweden). The BCI was positively and significantly correlated with the gross domestic product per person, the ambitions of the local authorities regarding water management, the voluntary participation index and governance indicators according to the World Bank (2013). The study also demonstrated a very significant correlation between the BCI and the University of Notre Dame Global Adaptation Index. The impacts of water scarcity and floods in cities are discussed. It is concluded that cities in transitional and developing countries are particularly at risk.

CIMAHI RIVER BENCHMARKING FLOOD ANALYSIS BASED ON THRESHOLD OF TOTAL RAINFALL

Flood in Cimahi city coming from the overflow of Cimahi river is a disaster that often occur in the middle Cimahi and extends downstream region namely Bandung Regency which is still included in the Cimahi Watershed. Flood in Cimahi can earlier be estimated when the design intensity of rainfall determined and calculate the flow of the river from upstream to downstream.The purpose of this study was to determine total rainfall that caused the peak river discharge of Cimahi river in upper and middle cross section and could easily received. The method used in this study is an early warning flood with benchmarking discharge based on rainfall-runoff models in the Cimahi watershed derived from unit hydrograph synthetic Nakayasu of Cimahi river. The results obtained from this study is the peak discharge of the Cimahi river upstream at Q= 1.41 m3 / s and in the middle of the cross section of Q = 2.12 m3 / s. Based on the measurements obtained bankfull discharge Cimahi river upstream cross section of 191.8 m3 / s and bankfull discharge in the middle cross section is 556.26m3 / s. With the drainage coefficient of Cimahi city based on land use obtained 0,57, then obtained a threshold total rainfall causes of flooding in the upper and middle is respectively as high as 239 mm and 460 mm. Threshold of Rainfall, bankfull discharge and Cimahi river cross section in this research integrated on the map namely Benchmarking Flood Diagram of Cimahi City that can be published to stakeholders and the public.

Urban Resilience to Flooding in Asia's Vulnerable Cities: Shanghai, Dhaka, Tokyo, and Taipei

Most of flooding hotspots by 2025 will be located in Asian nations (United Nations 2012). Damages from flooding will increase in correlation with increasing urbanization, risk, exposure, and vulnerability in Asia. Currently, four Asian cities, Shanghai, Dhaka, Tokyo, and Taipei, are the most vulnerable cities to flooding. In Shanghai or Dhaka, approximately 50% of its land is in flood-prone areas, the highest vulnerability to floods among coastal cities. Tokyo is one of the most populous urban agglomeration in Asia, with a population of over 37 million. Extensive urbanization in Tokyo suffers from severe damages once flooding occurs. In Taipei, flood-prone areas account for approximately 41% of its total land area in an extreme weather scenario. How and what planners can do to reduce the impact of flooding is an important consideration. Similarly, how governments prepare and plan for a resilient city should be a priority for many policy makers. In the future, rather than strengthening and rebuilding costly structures, Asian cities should focus on land-use and environmental planning for resilience as well as strengthening their organizations and funding to reduce disaster risk, maintain up-to-date risk and vulnerability assessment. Urban policies should include environmentally responsible development in the face of continued population and economic growth, and being resilient regarding natural disasters. Asian cities can adopt a growth management policy to direct development away from flooding hotspots. Urban regeneration policy should require developers to improve storm sewers, water retention ponds, and permeable surfaces. Planning more space for rivers, more constructed wetlands, and more ecological ponds to accommodate water is important. Cities can promote an actuarially fair flood insurance program which can reflect actual flood risks. A bottom-up community resilience plan would assist achieving urban resilience in Asian cities. Most important is the need of a strong political commitment and leadership to initiate and implement urban policies toward resilience. In doing so, urban resilience can be achieved in Asian cities.

Performance of Permeable Block Pavements in Accelerated Pavement Test and Rainfall Simulation

As industrialization advances, the increase in impermeable areas in urban regions has changed the water circulation system. Hence, many environmental issues such as heat islands and city floods have arisen. To solve this issue, related research with a high budget allocation is currently being carried out. A method of addressing this issue is to utilize permeable block pavements. The bearing capacity and hydrological efficiency of permeable block pavement with different base types was evaluated in this study using two accelerated pavement testings (APTs). Rutting was evaluated by performing a comparative analysis in each permeable block pavement. Furthermore, the hydrological characteristics were reviewed through a rainfall simulation experiment. The results of APT show that performance of permeable block pavements varies depending on the base type and traffic volume. Based on the result, it was demonstrated that the permeable block pavement is applicable for a vehicle road as well as the sidewalk. In addition, it was demonstrated that this pavement can improve the water circulation system.

Climate change adaptation: use and value of a climate buffer area

Most climate researchers agree that the changing world climate may irrevocably threaten life on our planet. It is no coincidence that water is involved in climate change, because the earth surface and atmosphere largely consist of water in different physical states and dimensions. Climate change becomes visible in less predictable and more severe weather conditions, like excessive rainfall and wind. These show up with a higher frequency and intensity, even in areas that never before experienced them. Seasonal patterns may fade or deepen and become more irregular. More sustainable human behaviour may on paper reduce the pace of or even reverse climate change. Widespread lack of such behaviour by a growing world population consciously replicating western-style consumerism makes it unlikely that real progress occurs in the foreseeable future. Comparable to an area like transport, only technical solutions may help to relieve the pressure. Water management has been used to allow humans to live safely on land for thousands of years. Many of the current water management systems are not up to the task anymore. Flooding of villages and cities is a growing global problem. Replacing out-dated systems is time consuming and very expensive, while political will seems hard to mobilize. But, if frequency and intensity of precipitation will stay at a higher level in future, cautious action is needed to prevent disasters. This paper will discuss a Dutch plan for a multifunctional area that would allow management of excessive water volumes. Adding a water retention area leads to higher investment costs, but benefits like enhanced protection may outweigh these higher costs. Given the unknown future risk and cost of flooding, damage costs may be much higher than assumed. From a no-regret perspective, it is wise to carry out projects, which currently have a (slightly) negative benefit-cost ratio. Keywords buffering, climate change, economic valuation, rainfall Language: en

Quantification of non-stormwater flow entries into storm drains using a water balance approach

To make decisions about correcting illicit or inappropriate connections to storm drains, quantification of non-stormwater entries into storm drains was performed using a water flow balance approach, based on data analysis from 2008 to 2011 in a separate storm drainage system in a Shanghai downtown area of 374ha. The study revealed severe sewage connections to storm drains; meanwhile, misconnections between surface water and storm drains were found to drive frequent non-stormwater pumping discharges at the outfall, producing a much larger volume of outfall flows in a short period. This paper presented a methodology to estimate quantities of inappropriate sewage flow, groundwater infiltration and river water backflow into the storm drains. It was concluded that inappropriate sewage discharge and groundwater seepage into storm drains were approximately 17,860m3/d (i.e., up to 51% of the total sewage flow in the catchment) and 3624m3/d, respectively, and surface water backflow was up to an average 28,593m3/d. On the basis of this work, end-of-storm pipe interceptor sewers of 0.25m3/s (i.e., 21,600m3/d) would be effective to tackle the problem of sewage connections and groundwater seepage to storm drains. Under this circumstance, the follow-up non-stormwater outfall pumping events indicate misconnections between surface water and storm drains, featuring pumping discharge equivalent to surface water backflow; hence the misconnections should be repaired. The information provided here is helpful in estimating the magnitude of non-stormwater flow entries into storm drains and designing the necessary pollution control activities, as well as combating city floods in storm events.

The Cork City flood of November 2009: Lessons for flood risk management and climate change adaptation at the urban scale

Flood hazards are a pressing challenge in several Irish and European cities and their impacts seem likely to intensify as climate change brings sea level rise, changes in storm patterns and increases in rainfall. Drawing on the example of Cork City and the November 2009 flood in particular, this paper evaluates contemporary policy and decision-making responses to flood hazards to determine whether they are sufficient to address current and future flood risks and vulnerabilities. It is clear that current policy and practice remains heavily influenced by a risk management paradigm that emphasises physical exposure and largely ignores socio-economic vulnerability. Floods and the losses they induce are seen as identical while engineering and technological fixes are viewed as the optimal means of reducing future flood losses. This framing of flood hazards is shaped by several influences including the historic evolution of flood policy and current institutional structures. The November 2009 flood highlights the limits of current policy and practice. Recent changes in national and European policy may also prove to be ineffective in facilitating effective adaptation and further changes in policy and practice are likely to be required.

Flood loss assessment in the Kota Tinggi

Malaysia is free from several destructive and widespread natural disasters but frequently affected by floods, which caused massive flood damage. In 2006 and 2007, an extreme rainfall occured in many parts of Peninsular Malaysia, which caused severe flooding in several major cities. Kota Tinggi was chosen as study area as it is one the seriously affected area in Johor state. The aim of this study is to estimate potential flood damage to physical elements in Kota Tinggi. The flood damage map contains both qualitative and quantitative information which corresponds to the consequences of flooding. This study only focuses on physical elements. Three different damage functions were adopted to calculate the potential flood damage and flood depth is considered as the main parameter. The adopted functions are United States, the Netherlands and Malaysia. The estimated flood damage for housing using United States, the Netherlands and Malaysia was RM 350/m2 RM 200/m2 and RM 100/m2 respectively. These results successfully showed the average flood damage of physical element. Such important information needed by local authority and government for urban spatial planning and aiming to reduce flood risk.

Photovoltaic Generation Potential of Paraná State, Brazil – A Comparative Analysis with European Countries

The theme of sustainable development has increasingly impacted the spheres of Brazilian society and has contributed to greater awareness to the need of natural resources conservation as well as issues on how to continue promoting socio-economic development of regions. One of the key issues for sustainable development is the generation of electricity with more use of renewable sources and, therefore, less environmental degradation. In this scenario, historically, Paraná State of Brazil has been one of the largest producers of electricity in the country, almost entirely from hydraulic source, due to the large existing river basin in the state. However, the use of this source in Brazil is declining due to depletion of water potential and also the pressure of society with respect to environmental, social and economic impacts caused by damming of rivers and flooding of cities and areas to form large reservoirs. To overcome these limitations, other sources have been studied and used, such as biomass and wind. Photovoltaic generation has been contemplated in Brazilian government policies only to supply electricity with off-grid systems in remote locations. However, due to the recent Resolution 482/2012 of ANEEL (Brazilian Electricity Regulatory Agency), which establishes rules for micro and mini-generation of electricity, it is possible that consumers install grid connected photovoltaic systems up to 1 MWp, as have been widely used in the urban environment installed or integrated on roofs as a form of distributed generation, particularly in Europe, where counts with installed capacity in GW range, while in Brazil it counts only with a few MW. Given this new perspective of growth of the Brazilian photovoltaic electricity generation this paper presents the potential of solar photovoltaic power generation in Paraná State, Brazil, with a comparative analysis with the potential presented by some European countries. The presented solar and photovoltaic maps uses irradiation data obtained from SWERA project (Solar and Wind Energy Resources Assessment), which was coordinated in Brazil by National Institute for Space Research (INPE). The results of this analysis can contribute to development of public policies related to projects and researches in photovoltaic aiming to spread the use of this renewable energy source in Paraná.

Flood Risk Mapping for the City of Toronto

The city of Toronto has experienced many major floods over the past century: the flood following hurricane Hazel in October 15, 1954, the August 27, 1976 floods, the August 19, 2005, and the flooding of July 8, 2013. During the latest flooding, some parts of the City of Toronto received over 120mm of rain, while the monthly average for Toronto is 74.4mm. The impact was felt as 300,000 residents were affected by power outages. Other serious disruptions included flight cancellations, subway and other transportation closures. It was the most expensive disaster for the province of Ontario. According to the Insurance Bureau of Canada, the damage of the insured properties exceeded $850 million. This event renewed a debate on a number of issues, such as decaying infrastructure, insufficient flood management, and inadequate standards. Don River, the main river crossing the city, is wide but not deep enough, which together with sedimentation contributes to frequent flooding of surrounding areas. In addition, natural creeks have been buried in sewer pipes, thus losing the natural waterways towards the lake Ontario and forcing existing rivers and creeks to overflow their banks. While floodplain maps are generally available, the estimation of flood risk maps based on population, economic development, and critical infrastructure will enhance city's flood mitigation and preparedness planning. In this paper, we present an approach for determining spatial flood risk index map based on population vulnerabilities and terrain morphological characteristics using a geographic information system.

Climate Change Vulnerability and Adaptation in Metro Manila

Climate change and flooding in Asian cities pose great challenges to the environmental and human security of the population and their governance systems. This paper examines the intersections of ecological-environmental and social vulnerability and the adaptive responses of urban poor communities and commercial-industrial establishments in Metro Manila to floods and other climate change-related effects, such as storm surges and sea-level rise (SLR). These weaken the communities’ ecological-environmental systems, threaten the well-being and security of the people and strain the resources of city governments. Disaggregating the ecological-environment vulnerabilities of a city/community according to specific places/spaces (or place-based vulnerabilities) that lead also to variable patterns among different groups (e.g., gender, income group, sector) of adaptive responses to flooding. Drawing a systematic sample of urban poor households and industrial-commercial establishments along the Pasig-Marikina River Basin of Metro Manila, this study utilised household surveys, key informant interviews, focus group discussions (FGD) and secondary data sources, in analysing the sources of their vulnerability and adaptive responses. Existing studies generally focus on the vulnerability and adaptation of urban-rural populations and do not highlight the interaction of place-based vulnerabilities with sector-specific vulnerabilities that reconfigure flood impacts and responses among the urban poor communities and commercial-industrial establishments during and after floods. In particular, poor and female-headed households residing in highly degraded environments or places/spaces within and across urban poor communities suffered higher damages and losses compared to better-off households and establishments. The interaction of these drivers of vulnerability further heightens and compromises the environmental and human security needs of poor people, their communities and those in the private sector that local/national government agencies need to respond.

An Analysis on the Urban Flood Control

The urban flood control should be regulated according to the topography, rivers and the regional economics of the city. The regulating reservoirs will be built or rebuilt in the mountain area upstream; the flood would be drawn downstream through the diversion channel. The flood in city would be reduced. The program would to control the rivers in urban area, reduce the elevation of rivers downstream by the non-engineering measure in order to decrease the effect of the backwater. In this paper, we suggested that the program of artificial damaged embankment and the flood compensation foundation as the main measures for flood control in urban area. The safety of the urban area will be ensured by both engineering measures and non-engineering measures from the flood of the rivers.