Flooding in Sri Lanka-
A common occurrence during
Monsoon seasons

Heavy thunderstorms hit northern Sri Lanka between 22 and 23 December 2018 bringing more than 250mm of rain to the Mullaitivu and Kilinochchi districts (Figure 1) (ReliefWeb, 2018; FloodList, 2019). This is widely reported as being the highest amount of rainfall recorded in a single day in these districts since 1983 (ReliefWeb, 2018). Within Mullaitivu district, Mannkulam division received 365.1mm of rain within 24 hours on 22 December 2018 (Flood List, 2019). To put the significance of this into context, the average annual rainfall in the Mullaitivu district is 1,340mm (Pirateeparajah, 2015).

Figure 1 (Left): 24-hour rainfall accumulation and distribution across Sri Lanka on 22 December 2018 (Data source: Pmm.nasa.gov, 2019). Figure 2 (Right): Number of damaged houses in each district division in Sri Lanka due to the floods in December 2018. Darker shades of purple show the highest number of damaged houses in any district – a total of 1,681 houses in Mullaitivu were reported damaged. (Data source: Disaster Management Centre, 2019)

Figure 3: Number of individuals affected in each district division in Sri Lanka due to the floods in December 2018. The darkest shade of orange represents a maximum of 40,000 individuals. (Data source: Disaster Management Centre, 2019)

The total rainfall within these two days accounts for 25% of the annual total and 50% of the average total rainfall for the Northeast monsoon season (Department of Meteorology, 2018). As of 6 January 2019, more than 123,000 people were affected, with two deaths reported (ReliefWeb, 2019). Kilinochchi and Mullaitivu suffered the greatest losses (Figures 2 and 3) as these two districts are amongst the least developed in Sri Lanka and the least prepared for such natural catastrophes.

Sri Lanka Monsoons

Sri Lanka has two distinct monsoon seasons and commonly experiences seasonal flooding due to extreme rainfall. However, different regions are likely to be flooded in each season. In general, the western and southern provinces are more susceptible to flooding during the Southwest monsoon, which occurs between May and September annually, while the northern and north-central provinces are more likely to be flooded during the Northeast monsoon, which happens between December and February each year (Ministry of Disaster Management, 2018). In addition to the monsoon seasons, tropical cyclones and tropical depressions form frequently in the Bay of Bengal during the summer months and bring high levels of precipitation to Sri Lanka.

May 2016 and May 2017 floods in Sri Lanka

Figures 4 and 5: Rainfall accumulation across 24 hours in Sri Lanka on 25 May 2016 (left) and 26 May 2017 (right) obtained using NASA satellite data. Therefore, there may be a difference between the reported data from ground monitoring systems and these satellite images. (Data source: Pmm.nasa.gov, 2019)

Sri Lanka has experienced several notable flood events in recent years, with the 2016 floods perhaps the most significant from an insurance perspective given the impact to livelihoods and properties around the capital city of Colombo. In May 2016, a tropical storm hit Sri Lanka and resulted in floods and landslides in 22 of the 25 districts. The Kelani Ganga (Kelani River) is one of the main river basins in Sri Lanka and flows through the centre of Colombo. The Kelani catchment experienced a total of 350mm of precipitation across a three-day period (15 to 17 May 2016). The torrential rain caused inundation, destroyed industrial and residential infrastructures and resulted in 104 fatalities.

During the event more than 4,000 houses were damaged and 620 houses were completely destroyed (OCHA, 2016). More than 340,000 people were affected during this event, which is three times as many as during the flooding that occurred in Kilinochchi in December 2018 (ReliefWeb, 2016). The southern districts were the worst hit given the spatial pattern of precipitation (Figures 4 and 5). These include highly populated areas such as Colombo and Gampaha. The economic damage to households was estimated as close to LKR 56 billion (USD $310 million) (Ministry of National Policies and Economic Affairs, Ministry of Disaster Management, 2016).

Torrential rain during the same monsoon season caused flooding in Sri Lanka a year later (May 2017). It affected at least half a million people and resulted in 140 deaths with widespread losses in Colombo, Gampaha, Kalutara, Galle and Matara. Due to the level of flooding in and around Colombo being less than the previous year (i.e. May 2016), the economic damage was lower, estimated at around LKR 29.05 billion (USD $160 million).

Sri Lanka’s National Insurance Trust Fund (NITF) operates a nationwide disaster relief programme – National Natural Disaster Insurance Scheme (NNDIS) - helping low income homeowners and microenterprises recover from natural disasters such as flooding. The NNDIS scheme is predominantly focused on supporting those in informal or semi-permanent houses, many of whom live within the floodplain of rivers such as the Kelani Ganga. These types of villages were among the worst affected during the 2016 and 2017 floods.

The NITF estimated that the total claims from the May 2016 floods amounted to approximately LKR 17 billion (USD $93 million), while the May 2017 floods had claims totalling to an estimated LKR 4 billion (USD $21 million). The May 2016 event also impacted many leading private insurance and reinsurance companies as the flooding in Colombo affected extensive industrial assets, whereas the 2017 flooding was predominantly in urban and suburban districts (Reuters, 2017).

Figure 6 (Left): An extract of the JBA 1-in-50-year Sri Lanka 30m River Flood Map. The area illustrated is Gampaha, Sri Lanka. (JBA Risk Management Limited™). Figure 7 (Right): The same area shown in Figure 6 based on obtained satellite imagery after the May 2016 flooding in Gampaha city, Sri Lanka. The extent of flooding observed in Gampaha is comparable to the JBA Sri Lanka 30m flood map. (Source: ReliefWeb, 2016).

Ongoing challenges

Sri Lanka’s population has been increasing steadily since the 1960s, from 9.8 million in 1960 to 21.4 million in 2016 (World Bank, 2019). Given Sri Lanka’s climate and the lack of flood protection for many of those living in unplanned, low-lying areas, flooding remains a clear and present danger across many parts of Sri Lanka. The number of annual flood events in Sri Lanka remains high and has been increasing over the years with 25 large floods having occurred between 2000 and 2013, affecting more than five million people. Given that the intensity and frequency of extreme weather events, such as heavy rainfall, looks set to increase in the near future (Handmer et al., 2012), these events will continue to pose a serious challenge to livelihoods.

Non-life insurance penetration currently remains very low in Sri Lanka – estimated in 2015 to represent around 0.62% of GDP (Oxford Business Group, 2017). Therefore, Sri Lanka’s National Natural Disaster Insurance Scheme (NNDIS) provides a positive initiative to help many recover from the effects of these devastating floods.

JBA Risk Management has nationwide return period flood maps for Sri Lanka at 30m resolution. Please get in touch for more information.

References 

Data.worldbank.org. (2019). The World Bank Data - Sri Lanka. [online] Available at: https://data.worldbank.org/country/sri-lanka [Accessed 10 Jan. 2019].

Disaster Management Centre (2019). Situation Report updated on 8th January 2019 at 1800hrs. [online] Available at: https://reliefweb.int/sites/reliefweb.int/files/resources/Situation_Report__on_2019__1546953481.pdf [Accessed 10 Jan. 2019].

Department of Meteorology. (2018). Climate of Sri Lanka. [online] Available at: http://www.meteo.gov.lk/index.php?option=com_content&view=article&id=94&Itemid=310&lang=en [Accessed 17 Jan. 2019].

FloodList (2019). Sri Lanka - Over 100,000 Affected by Floods After Days of Heavy Rain. [online] Available at: http://floodlist.com/asia/sri-lanka-floods-december-2018 [Accessed 10 Jan. 2019].

Handmer, J., Honda, Y., Kundzewicz, Z., Arnell, N., Benito, G., Hatfield, J., Mohamed, I., Peduzzi, P., Sherstyukov, B and Wu, S. (2012). Changes in Impacts of Climate Extremes: Human Systems and Ecosystems. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge.

Ministry of Disaster Management. (2018). Floods in Sri Lanka. [online] Available at: http://www.disastermin.gov.lk/web/index.php?option=com_content&view=article&Itemid=0&id=58&lang=en [Accessed 10 Jan. 2019].

Ministry of National Policies and Economic Affairs, Ministry of Disaster Management (2016). Sri Lanka Post-Disaster Needs Assessment. [online] Available at: http://documents.worldbank.org/curated/en/872611496221419957/pdf/115335-WP-PUBLIC-pda-2016-srilanka.pdf [Accessed 10 Jan. 2019].

Ministry of National Policies and Economic Affairs, Ministry of Disaster Management (2017). Sri Lanka Rapid Post Disaster Needs Assessment. [online] Available at: https://reliefweb.int/sites/reliefweb.int/files/resources/PDNA%20Sri%20lanka%202017-1.pdf [Accessed 10 Jan. 2019].

OCHA (2016). Sri Lanka: Floods and Landslides Situation Report No. 2 (as of 26 May 2016). [online] UN Office for the Coordination of Humanitarian Affairs. Available at: https://reliefweb.int/report/sri-lanka/sri-lanka-floods-and-landslides-situation-report-no-2-26-may-2016 [Accessed 10 Jan. 2019].

Oxford Business Group (2017). Sri Lanka 2017: Insurance. [online] Available at: https://oxfordbusinessgroup.com/overview/streamlining-market-steady-premium-expansion-continues-while-new-rules-are-expected-result-stronger [Accessed 15 Jan. 2019].

Pirateeparajah, N. (2015). Spatial and Temporal Variations of Rainfall in the Northern Province of Sri Lanka. Journal of Environment and Earth Science, [online] 5(15), pp.179-189. Available at: https://www.iiste.org/Journals/index.php/JEES/article/viewFile/25195/25799 [Accessed 14 Jan. 2019].

Pmm.nasa.gov. (2019). GPM Data Downloads | Precipitation Measurement Missions. [online] Available at: https://pmm.nasa.gov/data-access/downloads/gpm [Accessed 10 Jan. 2019].

ReliefWeb. (2018). Sri Lanka: Floods - Dec 2018. [online] Available at: https://m.reliefweb.int/disaster/47214/fl-2018-000425-lka [Accessed 10 Jan. 2019].

Reuters (2017). Fitch: Reinsurance Keeps Sri Lankan Insurers Afloat Amid Floods. [online] Available at: https://www.reuters.com/article/fitch-reinsurance-keeps-sri-lankan-insur/fitch-reinsurance-keeps-sri-lankan-insurers-afloat-amid-floods-idUSFit3h1Hdy [Accessed 10 Jan. 2019].

Standing Water Extent due to Flood on 16 May 2016 in Gampaha City of Sri Lanka as Observed by ALOS-2/PALSAR-2 RADAR Satellite. (2016). [pdf] Available at: https://reliefweb.int/map/sri-lanka/standing-water-extent-due-flood-16-may-2016-gampaha-city-sri-lanka-observed-alos [Accessed 10 Jan. 2019].

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