Keywords

13.1 Introduction

Flood occurs worldwide in var locations and in diverse magnitude, and thus this widespread hazard plays a marked and significant role in shaping the environment, economy, and society. Heavy rainfall, uneven distribution of rainfall, improper drainage system, decreasing and decaying of wetlands, etc. are often get aggravated together with the uncontrolled urban population growth and density leads to urban flood. Flood is a widespread devastating phenomenon as it affected more than 2 billion people worldwide between 1998 and 2017; loss of life, damages of property, and health hazards are the immediate effects of such incidences. Worldwide, people belong to low-lying areas and floodplains are the most vulnerable, but the urban areas are not an exception to fetch such incidences for diverse reasons. Urban flooding is considered as a type of pluvial flooding caused by surface run-off, and thus this concept is different from fluvial or coastal flooding. The physical characteristics and concrete infrastructure of the urban area and the rate of urbanization are the factors that increase the chances of water logging problem in a larger scale and enhance the occurrences flood. The flood management especially in urban areas is often becoming very challenging and a tough mission for the urban planners and policy-makers because it must enclose the wellbeing of the inhabited people, maximize the use of resources along with the minimization of human and economic loss and damages caused by the flood. Recently, the geospatial technology coupled with the Remote Sensing (RS), Geographic Information System (GIS) and Global Positioning System (GPS) has become the dominant and solution tool for flood mitigation and management. The vulnerability, risk proneness, flood-affected zones, and attainable areas could easily be found out and mapped through the GIS. Moreover, the advancement from optical to microwave remote sensing has developed in this field, which provides the all-weather capable data for mapping and analysis of flood hazard. The quantification and reduction of the damages, precaution and assessment of flood, identification of vulnerable areas and prediction of such events through the RS and GIS helps to minimize the harmful effects of flood and superior management can be provided with the diverse applicable ways by geospatial technology. Furthermore, the troubles of socio-economic motion together with transport and communication, contamination of drinking water, unavailability of food and loss of property, aftermath illness along with the structural damages are the consequences of urban flood (Hewitt and Burton 1971). The urban area located in the flat surface or low-lying terrain often have to adjust with the poorly build drainage and sewerage system which often have been blocked by disposed municipal waste. The unplanned or poorly planned urbanization makes the densely concentrated inhabitants vulnerable to urban flood, and therefore the damages become extrapassionate and complex to manage (Jha et al. 2011). Urbanization often found in turn of the switch of wetland, natural vegetation, agricultural land to build up setting, structure and infrastructural enlargement (Adoeye et al. 2009), which has a strong connection with the occurrence of urban flood. Thus, many factors are responsible for the occurrence of urban flood, such as duration and intensity of precipitation, clearance of natural vegetation, land use pattern, natural, quasi-natural and man-made impediments. All of these enhances the occurrence of flood, its frequency, duration of stay, magnitude, inundation and areal expand which are needed to judge for the mitigation and management, and the application of geospatial technology is the key apparatus for such effort. Different statistical and geospatial techniques have been successfully used for qualitative and quantitative analysis of urban flood to uncover the vulnerable and risk proneness, and thus it contributes a lot in the planning and formulation of appropriate flood management strategies. The magnitude of urban flood can be reduced if adequate emergency prevention, preparedness, response,and sustainable recovery measures are implemented in a timely manner.

Some important studies have been found describing the collision of urbanization and meteorological changes and its connection with the increasement of rainfall in urban area (Guhathakurata et al. 2011; Ghosh et al. 2009; De et al. 2005; De Roo 2000; Rao et al. 2004; Khole and Dey 2001; Roy et al. 2001; De and Rao 2004; Goswami et al. 2006; Sinha et al. 1999); rapport between urbanization and hydrological features like decrease in infiltration, incensement of runoff, increase the number and height of flood occurrence (Alaghmand et al. 2010). Some studies have found RS and GIS as very effectual in identifying the spatial section of flood management as it supplies adequate geographical information (Lowery et al. 1995; Smith 2001); GIS made the flood hazard identification, vulnerability assessment, monitoring and forecasting easier (Roy et al. 2001); while RS intended a synoptic attitude of spatial information, allocation and dynamism of hydrological episode employed to determine and monitor the flood, and quantification of the areal extend easily (Izinyon and Ehiorobo 2011). Currently, greater than 50% population of the world live in the urban area and this is going to accomplish two-thirds by 2050 (IFRC 2010; WHO 2010) and this could be very alarming so far the management of urban flood is concern. Furthermore, the urban flood is considered as dangerous catastrophic events across the globe and ranked as the commonest event with some serious consequences ranging from trivial to foremost accidental (Liu and Li 2017; Gharagozlou et al. 2011; Clement 2013; Ramlal and Baban 2008; Mark et al. 2004). Moreover, the flood risk is increasing with an escalation of hydrological and climatic variables (Masser 2001; Mathew et al. 2012;Messner and Meyer 2006; Mohit and Aktar 1998; Yi et al. 2010; Heywood et al. 1993; Huong and Pathiran 2013), thus and need of the hour is to reduce such urban flood risk in urban areas of the world. In most of the urban areas, the harsh nature of urban flood is exasperated by the predominantly occurred heavy rainfall; stumpy infiltration due to impervious facade, poor and unmaintained prior urban drainage infrastructure, accelerated surface runoff, and related inundation of low-lying areas (Liu and Li 2017; Few 2003; Chen et al. 2009; Fernandez and Lutz 2010). Such urban flood events are often amplified by the consequences of climate change and unplanned and extensive urban expansion, and therefore diverse techniques have to be employed for effective and efficient management. In this regard, the prologue exercise of geographical information systems (GIS) has improved the estimation of urban floods, identifying poor zones, finding risk-prone zones using diverse analysis and modelling of flood-causing essentials like precipitation, river discharge, drainage systems, depth of groundwater table, and slope to deal the perilous nature of urban floods for resilient management. Different aspects of urban flood elements have been analyzed using multi-criteria spatial analysis, overlay analysis, employment of different models using GIS techniques, and with the help of systematic integration of structural and non-structural events with the community level, flood risk can be lessened to some extent or to an acceptable level.

13.2 Common Concepts in Flood and Flood Management

The relevant and important terms that are closely associated with the urban flood and its management are mentioned in the form of a flowchart (Fig. 13.1).

Fig. 13.1
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Flowchart of concepts of flood management

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Flood hazard: In a specific time within an area, the occurrence of an urban flood event showing its potentiality and magnitude and the several factors dependent on it (Crichton 2002; Kron 2005; Dang et al. 2010). The frequency of occurrence, warning time, rate, and increase of water levels, flood depth, duration, velocity, etc. are very important in flood management.

Flood vulnerability: The physical, economic, social, environmental conditions that make the population more susceptible to urban flood hazard is known as flood vulnerability, which has been judged in numerous studies (Alcantara-Ayala 2002; Pelling 2003; ISDR 2004; Barroca et al. 2006; Adelekan 2011). This vulnerability should be studied as vulnerability indicators, susceptibility, exposer, and coping indicators (Weichselgartner 2001; Adelekan 2011) and such kind of information is paramount in determining the flood risk.

Flood risk: The hazards and its potential loss is generally amounted by the flood risk (Crichton 2002; Kron 2005) which signifies the overall effects of urban flooding including the treats of life, danger, evacuating of people, potential damages to the structure, buildings, social disruption, loss of production and community belongings, etc. Thus the flood risk is often expressed by the formula: Flood Risk = Flood hazard x Flood vulnerability (Dang et al. 2010; Karim et al. 2005; Kron 2005; Apel et al. 2009).

Flood damage: The impact of flood damage can be assessed by the amount of flood damage both in tangible and intangible form, which includes agricultural and environmental damages, business interruption, health, etc. (Pielke and Downton 2000; Munich and Topics 2005; Dutta et al. 2003).

Flood management: Urban flood has been gaining increased attention over the years because of the increased rate of urbanization and its connections with the hazards, and significant damages caused to populace, livestock, health, assets, bridges, buildings, communication, homes, and business (Ramlal and Baban 2008; Chen et al. 2009; Few 2003; Mark et al. 2004). In the developed countries, these hazards are devastating to the cities in diverse ways mostly due to notably extreme precipitation events coupled with dilapidated drainage system generated by over urbanization. The urban flood management reducing its potentiality includes proper and timely analysis of risk assessment employing interdisciplinary approaches with the help of RS and GIS (Barbosa et al. 2012; Chen et al. 2009). The application of RS and GIS techniques in all the four stages (Prediction, Preparation, Prevention and Mitigation and Damage Assessment) of flood management is incredibly effective and fruitful as it has updated and potential appliances.

13.3 Flood Management with the Application of RS and GIS

RS and GIS can provide information about predicted flood events in order to facilitate early prediction and planning and to build up an improved management system. Thus, effective and efficient planning with the help of some models and methods by using geospatial techniques for urban flood management was well adopted in some urban areas of the world. Some of the models like, WetSpa, HYDROTEL, LISFLOOD, TOPMODEL, SWAT, (Wang et al. 2011; De Smedt et al. 2000; Fortin et al. 2001; De Roo et al. 2000; Quinn et al. 1991; Arnold et al. 1998; De Smedt et al. 2002); Digital Elevation Model (DEM) and hydrological models were increasing popularity as these models include the data of land use and land cover, river discharge, rainfall amount, rainfall frequency, surface roughness, spatial and temporal information, etc. Some have used multispectral RS data for employing GIS-based models like Normalized Difference Vegetation Index (NVDI), DEM (Townsend and Walsh 1998; Konadu and Fosu 2009); while several studies worked on different GIS-based hydrological models (De Roo et al. 2000; De Smedt et al. 2000; Usul and Tarun 2006; Batelaan et al. 2007; Chormanski et al. 2008; Stancalie et al. 2009; Kabir et al. 2011) in a more simplified manner to predict flood. The application of geospatial technology in urban flood management is grouped into a single frame (Fig. 13.2).

Fig. 13.2
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Application of geospatial techniques for flood management

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13.3.1 Flood Hazard Mapping

The identification of potential urban flood-prone area, risk-prone area and probable threat area is very essential in flood management, and this helps the planner, government, and even Non-Governmental Organizations (NGOs) to concentrate on the priority areas, allocating resources in proper areas. In this regard, the application of geospatial technology have proved powerful in predicting potential flood risk, vulnerability, and hazard (Islam and Sado 2000; Brivio et al. 2002; Hardmeyer and Spencer 2007; Singh and Sharma 2009; Stancalie et al. 2009; Konadu and Foshu 2009; Davor et al. 2016; Farnandez and Lutz 2010; Joy et al. 2019; Patel and Srivastava 2013; Singh and Kanga 2017; Sowmya et al. 2015) as the maps provide simplified information on the flood depth, velocity, direction of flow, inundated area, etc. The season wise (dry and wet) analysis of remote sensing-based satellite data can easily be comparable with the flood inundation models (Samarasinghea et al. 2010) and hydrological models, and helps to validate the accurate information of flood simulation and flood risk mapping in any urban area. The application of recent RS data like Landsat Enhanced Thematic Mapper Plus (ETM + ) and ERS (European Space Agency) SAR(Synthetic Aperture Radar) imageries to recognize and categorize the flood depth, flooded zones, and non-flooded areas (Sanyal and Lu 2004; 2005; Solheim et al. 2001) helps to predict floods (Ramlal and Baban 2008; Correia et al. 1999) and build up urban flood resilient strategies.

13.3.2 Mapping of Urban Features

As the anthropogenic inputs are very prompt in urban areas and have a larger contribution in occurrence of flood, various factors including urban growth scenarios are needed to consider, and this is the importance of geospatial technology. Urbanization enhances the trend of urban flood and it is anticipated that more than five billion people athwart the globe will inhabit the mega urban areas by the year 2025, which could aggravate the occurrences of urban flood (Masser 2001; Sorensen et al. 2016; Fernandez and Lutz 2010). Therefore, worldwide urban planner, civil engineers, architects, scientist, and environmentalist come forward together for updated and sustainable city planning to reduce the diverse effects of dissimilar hazards like urban flood and other issues. In this context, the geospatial technology easily pointed out the complex network of urban infrastructure, both natural and man-made features using various RS-GIS methods. Similarly, the changes of Land Use Land Cover (LULC) have some serious and valuable non-stop and indirect contributions in the discrepancy and disruption of hydrological cycle and which awkwardly later causes urban flood (Dai et al. 2001; Correia et al. 1999; Betel and Moghanm 2011; Weng 2001; DeVantier and Feldman 1993), and this could be addressed by the application of geospatial technology. Moreover, the spatio-temporal changes of urban expansion can be studied using this technology, which is very effective and necessary to formulate resilient flood management plans. Moreover, it is imperative to note that geospatial technology helps in site selection for waste disposal, location of wetlands, concentration of build up areas and ground water assessment (Dai et al. 2001; Chen et al. 2009; Correia et al. 1999) and facilitate new avenues in building 3D urban mapping models (Esri 2014) for appropriate urban ecosystems environment, urban land use planning, natural hazards identification, etc.

13.3.3 Preparation of Hydrological Models

In most of the urban areas, the developmental works affect the hydrological setting and water system, and the parameters like rainfall amount, duration, frequency, infiltration, surface runoff, water discharge, water stagnation, inundation, water balance, etc. can effectively be incorporated in building hydrological models for urban flood management with the application of geospatial technology. Thus, with employment of advanced, affordable, available RS and GIS software, the planner can fruitfully develop the proficiency to manage, manipulate, analyze, and display spatial information of urban flood (Sample et al. 2001; Mark et al. 2001; Lekuthai and Vongvisessomjai 2001; Meyer et al. 1993; Tsihrintzis et al. 1996; Lee and Heaney 2003; Diaz-Nieto et al. 2008). The employment of such models helps to attenuate urban flood, quick assessment of sinks, and probable areas of urban flooding for building sustainable resilient strategies. In this regard, the open-source RS data, like Google Earth permits to be updated by the users which could be greatly applied in urban planning, land use planning, infrastructural planning, and fed into an integrated urban flood management plan as it depicts the ground-level scenario (Penanowski et al. 2007; Patterson 2007; Schumann et al. 2007; Liu et al. 2005; Smith and Lakshmanan 2006; Sheppard and Cizek, 2009; Whitmeyer 2012; Yu et al. 2008; Chien and Tan 2011; Yu and Gong 2012). Moreover, despite some challenges in the utilization of geospatial technology, many researchers, planners, and government officials are using this sophisticated technology, and thus it gained sombre attention from the users to analyze the miscellaneous and imperative spatial and geo-referenced datasets for the superior urban flood management integrating the local plans, diverse systems, and framework.

13.3.4 Flood Management Strategies

The flood management strategies, especially for the urban area has some solemn methodological consequences and steps to be followed. In this process, strengthening and improving the existing flood management infrastructure, proper planning, policies formation and community awareness, training, capacity building are considered as the pillars (Fig. 13.3).

Fig. 13.3
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Strategies of urban flood management

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It is also imperative to collect the historical records, secondary data, and information from various sources and websites about the flood occurrences; and for the minute observation of the flood scenario, primary survey needs to be completed for the statistical analysis of the ground level urban flood scenario of an urban area. The groundwater data have to be acquired from different sources, and groundwater zonation map, identification of the low-lying areas using Digital Elevation Model (DEM), flow direction map of running water, zonation of water inundation level, Land Use Land Cover (LULC) maps, etc. should be analyzed and mapped and finally statistical methods have been applied for hazard and risk zonation map of urban flood. Moreover, the post-incidence part is also important and the employment of geospatial techniques in all phases is becoming powerful for the formation of proper mitigation and to build up resilient strategies for superior management. The methodological steps that usually follows in the application of geospatial technology in urban flood risk assessment and monitoring the management is mentioned systematically in the form of a diagram (Fig. 13.4).

Fig. 13.4
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Application of geospatial technology in flood risk assessment for monitoring management

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A number of recommended measures for the formulation of flood management strategies as recognized in various studies in the context of Indian cities, in combination of the National Disaster Management Guidelines (2010) are grouped into a single window (Fig. 13.5).

Fig. 13.5
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Flood Management Strategies

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13.4 Conclusion

The urban flood occurred primarily due to long-term anthropological reasons and natural situation, still everywhere the anthropological causes are largely highlighted; but the physical settings, climatic conditions, geological, and geomorphological characteristics of the area is also responsible to large extent. The existing review works demonstrate how the urban flood be triggered according to the location, physical setting, and anthropogenic upshots, and all these are efficiently explained with the application of geospatial technology. This geospatial technology with the combination of RS and GIS techniques deals with the various aspects of flood issues and holds best to manage the urban flood by prevention, preparedness, and relief management. It also helps to take the appropriate, location-specific flood management strategies, and policies, and if the remedial measures are taken accurately, the effect of such disaster can straight forwardly be reduced and confined into a reduced amount of valuable hazard in near future. Furthermore, this geospatial technology is capable to update and amend the existing flood management system by supplementing or complementing with the combination of various mapping and employment of hydrological (WetSpa, HYDROTEL, LISFLOOD, TOPMODEL, SWAT, HEC-RAS etc.) and RS based models/methods (DEM, NVDI, NBCI, LULC etc.), and thus, this technology has enormous prospect in preparedness in flood proneness, risk assessment, and relief management of every urban spot. Finally, it reveals that the current review effort definitely helps to sketch future research on flood risk analysis and management matters, strategy building, and finding innovative approaches in any urban vicinity employing the geospatial technology.