International Journal of River Basin Management ISSN: 1571-5124 (Print) 1814-2060 (Online) Journal homepage: http://www.tandfonline.com/loi/trbm20 A Brief review of flood forecasting techniques and their applications Sharad Kumar Jain, Pankaj Mani, Sanjay K. Jain, Pavithra Prakash, Vijay P. Singh, Desiree Tullos, Sanjay Kumar, S. P. Agarwal & A. P. Dimri To cite this article: Sharad Kumar Jain, Pankaj Mani, Sanjay K. Jain, Pavithra Prakash, Vijay P. Singh, Desiree Tullos, Sanjay Kumar, S. P. Agarwal & A. P. Dimri (2018): A Brief review of flood forecasting techniques and their applications, International Journal of River Basin Management, DOI: 10.1080/15715124.2017.1411920 To link to this article: https://doi.org/10.1080/15715124.2017.1411920 Accepted author version posted online: 07 Dec 2017. Published online: 22 Jan 2018. Submit your article to this journal Article views: 21 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=trbm20 INTL. J. RIVER BASIN MANAGEMENT, 2018 https://doi.org/10.1080/15715124.2017.1411920 A Brief review of flood forecasting techniques and their applications Sharad Kumar Jaina, Pankaj Manib, Sanjay K. Jaina, Pavithra Prakashc, Vijay P. Singhd, Desiree Tullose, Sanjay Kumara, S. P. Agarwalf and A. P. Dimrig aNational Institute of Hydrology, Roorkee, India; bNational Institute of Hydrology, Regional Center, Patna, India; cPostdoctoral Researcher, University of California, Davis, USA; dTexas A and M University, College Station, Texas, USA; eOregon State University, Corvallis, OR, USA; fIndian Institute of Remote Sensing, Dehradun, India; gJawaharlal Nehru University, New Delhi, India ABSTRACT ARTICLE HISTORY Flood forecasting (FF) is one the most challenging and difficult problems in hydrology. However, it is Received 14 August 2016 also one of the most important problems in hydrology due to its critical contribution in reducing Accepted 22 November 2017 economic and life losses. In many regions of the world, flood forecasting is one among the few KEYWORDS feasible options to manage floods. Reliability of forecasts has increased in the recent years due to Flood forecasting; models; the integration of meteorological and hydrological modelling capabilities, improvements in data uncertainty; updating; collection through satellite observations, and advancements in knowledge and algorithms for applications analysis and communication of uncertainties. The present paper reviews different aspects of flood forecasting, including the models being used, emerging techniques of collecting inputs and displaying results, uncertainties, and warnings. In the end, future directions for research and development are identified. 1. Introduction and consequences of ageing flood management infrastructure Among all observed natural hazards, water-related disasters are profound, as demonstrated in the United States (ASCE are the most frequent and pose major threats to people and 2013), resulting in flood infrastructure that does not provide socio-economic development (Noji and Lee 2005, ICHARM the intended level of protection and/or is subject to failure 2009). Over the period of 1900-2006, floods accounted for without major and costly maintenance. Furthermore, struc- about 30% of the total number of natural disasters, claiming tural measures are designed for specific flood events (i.e. more than 19% of the total fatalities and more than 48% of the 1% annual exceedance (country specific)), which is proble- total number of people affected (ICHARM 2009). ICHARMv matic because channel modifications, land use and climate (2009) also reports that water-related disasters account for change have resulted in nonstationarity and increasing about 72% of the total economic damages caused by natural hydrologic uncertainty, making the likelihood of floods less disasters, out of which 26% of all the damages are attributed predictable. As a result, structural measures are always subject to floods. These losses are expected to escalate in the future to residual risk. due to climate change, land use change, deforestation, rising As a result, experts (Gleick 2003, Brooks et al. 2009, sea levels, and population growth in flood-prone areas, caus- Opperman 2014) have called for transitioning from structural ing the number of people vulnerable to flood disasters glob- flood measures to non-structural flood protection measures ally to increase to two billion by 2050 (Bogardi 2004, that reduce exposure to floods, including regulation of land ICHARM 2009, Vogel et al. 2011). use and flood forecasting, among others, in flood-prone Development of optimal flood forecasting and viable flood areas that are already occupied. Non-structural measures pro- risk management systems have been advocated as measures vide more reversible and less-expensive mechanisms to of flood preparedness (Arduino et al. 2005, WMO 2011a) reduce flood risk than structural actions (DiFrancesco and for a variety of reasons. Due to the uncertainties surrounding Tullos 2014). Hence, non-structural measures are equally the magnitude, timing and place of occurrence, geographical emphasized, while planning flood risk management systems extent, and geophysical interactions of floods, it is often not (WMO 2011b). This paradigm shift is necessarily synchro- possible to completely control them. As a result, complete nized with advancements in the instrumentation and remote protection from floods is not always considered as a viable sensing of the atmosphere and earth surface and in the fore- alternative (Moore et al. 2005). Traditional flood manage- casting of natural hazards. ment, primarily composed of structural protection measures Floods can be of many different types and scales and this (i.e. dams and levees), emphasizes modifying a flood’s charac- drives differences in the architecture and implementation of teristics to reduce the peak elevations and spatial extents. flood forecasting systems. For example, flood forecasting sys- Although structural measures (e.g. dams and embankments) tems have been implemented at global (Alfieri et al. 2013), reduce flood risk, they cannot completely eliminate it. In continental (Thiemeg et al. 2015), basin (Hopson and Web- addition, these measures are not feasible in some areas (i.e. ster 2010), and community scales. In addition, flood forecast- remote mountain areas), are not effective for all flood pro- ing systems have been implemented for different types of cesses (i.e. glacial lake outburst floods), and generate undesir- floods. Plate (2009) distinguished five different types of land- able environmental impacts (Tullos 2008). Moreover, the cost scapes with characteristic flooding behaviour: a) high CONTACT Sharad Kumar Jain [email protected] National Institute of Hydrology, Roorkee, India © 2018 International Association for Hydro-Environment Engineering and Research 2 S. K. JAIN ET AL. mountain ranges, which are mainly subject to flash floods and (HESS). However, these reviews are either outdated given the geophysical flows, b) foothill areas where floods are caused by rapid advancements made in FF or are narrowly focused on intense rainfalls and snowmelt, and where inundation is specific aspects of flood forecasting algorithms and models. widespread, c) large floodplains where velocities are low The objective of this review is therefore to provide a current, and floods occur because the landscape is unable to quickly concise, and comprehensive review of flood forecasting prac- pass all the incoming flows, d) urban areas where flooding tices targeting professionals seeking to implement and/or use is generated by inadequate sewer capacity and numerous bar- flood forecasting. riers to flow, and e) coastal areas where flooding is typically caused by cyclones and storm surges. These different flood 2. Elements of a flood forecasting (ff) system types require different architecture and implementation of FF. For example, flash floods are associated with spatially The purpose of a flood forecasting and warning system and/or temporally intense precipitation or by a sudden (FFWS) is to alert the general public and concerned auth- release of water due to dam breach and lake outburst. Flash orities of an impending flood as much in advance, and floods are not common but can have high societal impacts with as much reliability, as possible. The main components because of their heavy precipitation and rapid onset (within of an FFWS (Figure 1) include: (i) data (hydrological, a few hours of rainfall) (Doswell et al. 1996). Response time meteorological) collection and transmission; (ii) forecast- is thus very small; so flash flood forecasts are heavily depen- ing, which involves analysis of observations as well as pre- dent on real-time assimilation of precipitation data and fore- diction of future rainfall, water elevations and discharge casts, and yet flash flood predictions are still subject to for periods varying from a few hours to a few days important limitations (Kelsch 2001, Collier 2007, Hapuarach- ahead; and (iii) dissemination of information to user chi et al. 2011). Alternately, storm surge flooding, which agencies and communities. occurs during a storm, cyclone, or hurricane, produces a mas- Among the various products, the most useful outputs of sive wave of water that sweeps onto coastal areas. As a result FFWS are river elevations, inundation extent, and time of of the unique characteristics of storm surges, flood forecasting