Journal of Xi'an University of Architecture & Technology ISSN No : 1006-7930 Disaster Risk Reduction and Modification Strategy for Settlement Pattern in the Context of Flood-2018: Thrissur District K.V. Vishruth Doctoral Student, School of Planning and Architecture, University of Mysore, Mysuru-570006. Karnataka. Bigith v.b Doctoral Student, School of Planning and Architecture, University of Mysore, Mysuru-570006. Karnataka. Dr. H.S. Kumara Associate Professor, Urban and Regional Planning, School of Planning and Architecture, University of Mysore, Mysuru-570006. Karnataka Abstract The geographical location, weather pattern and high population density of Kerala makes it prone to severe natural as well as human- induced disasters which can be countered only through organised mitigative actions. The State of Kerala is prone to a lot of natural hazards such as coastal erosion, flood, drought, lightening, landslide and earthquake. Almost all districts of Kerala are multi-hazard prone. In Kerala lightning, landslides (debris flows) and floods are the most commonly occurring natural hazards. The selection and implementation of flood mitigation measures that comprises of structural and non-structural measures is a complex process. This paper examines the factors that had lead to the occurrence of flood in Thrissur district of kerala,India and methods to be adopted in the future to avoid the severity due to flood. Based upon the study conducted all local bodies in the district is divided into various zones and various flood reduction strategies are discussed. These findings point to the importance of tailoring government policies and programs to the specific context in which flood mitigation occurs. Keywords: Human-induced disasters ,Natural hazards, Multi-hazard prone, Flood mitigation. Volume XIII, Issue 4, 2021 Page No: 623 Journal of Xi'an University of Architecture & Technology ISSN No : 1006-7930 1.Introduction Climate Change is significantly increasing the likely hood of compound hazards and cascading impacts on society (Glasser 2019). The Inter-governmental Panel on Climate Change (IPCC 2018) determined that the planet is likely to warm by 1.5°C (the lower limit set in the Paris Climate Agreement)as early as 2030 and highlighted the enormous challenge of preventing further warming. Various studies based on hydrologic models report the impact of climate change on water resources (e.g., Querner, 1997;Wilkinson& Cooper, 1993). It is likely that with climate change flooding events will increase in frequency and inten-sity. Globally, the risks posed by floods are expected to increase because of the combination of climate change (Collins et al.,2014; Bloschl et al.,2015) and changing land use sand land cover (Wheater and Evans, 2009; Pattison and Lane, 2012).Climate change is increasing the frequency of many sudden-onset hazards. As EASAC (2018) points out: The number of floods and other hydrological events have quadrupled since 1980 and have doubled since 2004.Climatological events, such as extreme temperatures, droughts, and forest fires, have more than doubled since 1980. Meteorological events, such as storms, have doubled since 1980. Sharmila and Walsh (2018), suggesting that climate change is shifting tropical cyclones into new areas of Eastern Australia, where many structures have not in the world. More than half of global flood damages occur in Asia. (T. Tingsanchali,2012) Causes of floods are due to natural factors such as heavy rainfall, high floods and high tides, etc., and human factors such as blocking of channels or aggravation of drainage channels, improper land use, deforestation in headwater regions, etc. Floods result in losses of life and damage properties. The world’s river deltas and coastal cities are increasingly vulnerable due to pressures from climate change, relative sea level rise, and population growth (Mulder et al.,2009;Renaud et al.,2013). Therefore, in densely populated deltas and estuaries spatial planning is challenged to enable socio economic developments and well-designed water management to provide services such as flood risk management, fresh water supply, and good environmental conditions. Considerable efforts have been made to compare adap-tation approaches among different areas in the world. These comparisons focused on flood risk strategies (e.g.Wilby& Keenan 2012;Ward et al.,2013), climate proofing of coastal cities (Aerts et al.2013), vulnerability and adaptive capacity of deltas (Bucx et al.,2010), or deltaic tipping points (Kwadijk et al.,2010;Renaud et al.2013). In practice, the selection of which flood mitigation measures to implement is a complex process. Because of its jurisdiction over land use and its responsibility for local public infrastructure, municipal governments are often tasked with this decision (Carter, 2012; Berke et al., 2014). By adopting an intensive qualitative approach we are able to examine the decision-making process leading to flood mitigation. (Swanborn, 2010), This approach uniquely allows us to illuminate the considerations of municipalities as they choose between the type and extent of flood mitigation.External factors including environmental regulations, state and federal grant programmes, and third party collaborations also serve to both aid and hinder municipal implementation of flood mitigation. (M. Consoer and A. Milman, 2018 ). Structural measures are favoured in situations in which portions of adjacent residential areas are situated about the maximum flood level, or when it is important to protect land adjoining a river from inundations due to an existing flood risk (Ghanbarpour et al., 2013) . In flood mitigation strategy the rural and urban distinction is important because rural and urban areas experience climatic hazards differently (Lal et al.,2011; Hales et al.,2014) and the implementation challenges they encounter are unique to their differing contexts. Volume XIII, Issue 4, 2021 Page No: 624 Journal of Xi'an University of Architecture & Technology ISSN No : 1006-7930 2.Background of study Unusual high rainfall during the monsoon season caused severe floods in Kerala from 15 August 2018. According to the State government, one-sixth of the total population of Kerala had been directly affected by the floods and related incidents. The central government had declared it a Level 3 Calamity, or "calamity of a severe nature". Over 483 people died, approximately one million people were evacuated, mainly from Chengannur, Pandanad, Edanad, Aranmula, Kozhencherry, Ayiroor, Ranni,Pandalam, Kuttanad, Aluva, and Chalakudy,N.Paravur, Chendamangalam, Eloor and few places in Vypin Island. Thirty-five out of the fifty-four dams within the state were opened for the first time in history. All five overflow gates of the Idukki Dam were opened at the same time, for the first time in 26 years. Heavy rains in WayanadandIdukki have caused severe landslides and have left the hilly districts isolated. Kerala received heavy monsoon rainfall, which was about 256% more than the usual rain fall in Kerala (Rainfall data -2018,Meterological department), on the mid-evening of August 8, resulting in dams filling to capacity; in the first 24 hours of rainfall the state received 310 mm of rain. Almost all dams had been opened since the water level had risen close to overflow level due to heavy rainfall, flooding local low-lying areas. For the first time in the state's history, 35 of its 54 dams had been opened. Flood 2018 along with landslides caused several severe damages in Thrissur district including the death of 62 people. About 1, 37,932 houses were affected and 2, 49,886 peoples were made provision for stay at camp. Among 256 villages in Thrissur, 91 were severely affected and 140 were partially affected only 25 were left unaffected. Due to the flood of 2018 about 1073 public buildings were affected and 91438 open wells were polluted. For the purpose of cleaning 8466 squads were formed in the district (Flood Statics-2018, Revenue Department, Thrissur). Nearly 25% of the total area is affected by flood.The intensity of flood was severe at 2.5% of the total area. These area areas flooded beyond 3m depth. Chalakkudy,Kodungallur and some regions of Mukundapuram and Thalappilly taluks come under this category.Out of the total area of 3035sq.km of the district, 751 sq.km area is affected from flood. (Flood Survey,Town and Country Planning Department,Thrissur). 3.Profile of the District Thrissur which is the cultural capital of Kerala has derived its name from ‘Thrissivaperur’ meaning ‘the abode of Lord Shiva’. The religious, historical and archeological cultures are remarkable in the District and hence the development of tourism gets focused well.The District posseses excellent network of transportation system with good quality roads including National and State highways.Thrissur District is in the central region of Kerala state lying between 10°10’ and 10°46’ north latitude and 75°57’ and 76° 54’ east longitude. Figure 1.Location of Thrissur district Volume XIII, Issue 4, 2021 Page No: 625 Journal of Xi'an University of Architecture & Technology ISSN No : 1006-7930 The area of Thrissur District is bounded on the north by Malappuram and Palakkad District, south by Idukki and Ernakulam Districts, east by Palakkad District and Coimbatore District of Tamil Nadu and west by the Arabian Sea. The location of Thrissur district is shown in figure below. The land profile of the Thrissur District slopes down from the Western Ghats in the east to the Arabian Sea to the west forming three distinct natural divisions-the Highlands, the Midlands, the Coastal belt. 3.1.Demographical Profile Thrissur District has a land area of 7.8% of kerala’stoal land area. The population of Thrissur district is 31,21,200 which is 9.34% of the state Population. Out of the district population 14,80,763 are males and 16,43,437 are females. While comparing with population of other districts, Thrissur district stands in 4 th place. Comparison of Population between Thrissur District and Kerala state is given in table When we examine the population of last 3 decades, Thissur district shows a decreasing trend in the case of growth rate.