Distribution of Lightning Accidents in Sri Lanka from 1974 to 2019 Using the Desinventar Database

Home , 2019 in Sri Lanka, Districts of Sri Lanka, Kalutara, Kalutara District, Kegalle District, Kurunegala

International Journal of Geo-Information

Article Distribution of Lightning Accidents in Sri Lanka from 1974 to 2019 Using the DesInventar Database

Mahesh Edirisinghe * and Uruvitiya Gamage Dilaj Maduranga

Department of Physics, University of Colombo, Colombo 00300, Sri Lanka; [email protected] * Correspondence: [email protected]

Abstract: The reported lightning accidents that are available in the DesInventar database—which consist of 549 deaths, 498 injured people, 39 destroyed houses, and 741 damaged houses—were analyzed in terms of their geographical and temporal variation. The average lightning flash densities were calculated using zonal statistics using the geographic information system (GIS), referring to the respective raster maps generated based on Lightning Imaging Sensor (LIS) data from the Tropical Rainfall Measurement Mission (TRMM) Satellite. Hence, the variations of the lightning accidents— monthly and climate season-wise—in response to the lightning flash density were also reported. The calculated average lightning flash density in Sri Lanka is 8.26 flashes km−2 year−1, and the maximum average lightning flash density of 31.33 flashes km−2 year−1 is observed in April in a calendar year. April seems to be more vulnerable to lightning accidents, as the maximum number of deaths (150 deaths) and injuries (147 injuries) were recorded in this month. Most of the high-risk lightning accident regions that were identified in Sri Lanka are well known for agricultural activities, and those activities will eventually create the platform for lightning victims. In Sri Lanka, in a year, 12 people were killed and 11 people were injured, based on the reported accidents from 1974 to Citation: Edirisinghe, M.; 2019. Conversely, a substantial increase in the number of deaths, injuries, and incidents of property Maduranga, U.G.D. Distribution of damage has been observed in the last two decades (2000–2019). On average, for the period from 2000 Lightning Accidents in Sri Lanka to 2019, 18 people were killed and 16 people were injured per year. Furthermore, considering the from 1974 to 2019 Using the DesInventar Database. ISPRS Int. J. population of the country, 0.56 people per million per year were killed, and 0.51 people per million Geo-Inf. 2021, 10, 117. https:// per year were injured due to lightning accidents based on the reported accidents from 1974 to 2019. doi.org/10.3390/ijgi10030117 Moreover, for the 2000–2019 period, these estimated values are significantly higher; 0.86 people per million per year were killed, and 0.77 people per million per year were injured. Academic Editors: Wolfgang Kainz and Milan Konecny Keywords: lightning; lightning accidents; lightning hazards; lightning risk; lightning safety; lightning flash density; disaster management; disaster preparedness; disaster mitigation; DesInventar Database Received: 16 December 2020 Accepted: 24 February 2021 Published: 27 February 2021 1. Introduction Publisher’s Note: MDPI stays neutral Lightning is an electrical discharge which is mostly due to an inter-cloud, intra-cloud, with regard to jurisdictional claims in or cloud to ground electrical imbalance. It is spectacular, but it is also dangerous. The published maps and institutional affil- high values of current and relevant energy of a lightning flash are potent enough to kill iations. people and animals, and destroy property. There are about eight million lightning flashes a day all over the world, and an infrequent 0.2–0.8 people per million per year are killed by lightning in some geographical locations [1,2]. Furthermore, some of the people affected by lightning accidents may experience a variety of injuries, including severe burns, cardiac Copyright: © 2021 by the authors. arrest, or other symptoms, which may last for a longer period. Licensee MDPI, Basel, Switzerland. A comprehensive study about regional lightning activities is an essential requirement This article is an open access article to mitigate the lightning hazards of a country by identifying the highly lightning-active distributed under the terms and seasons and regions of that country. Detailed studies have been conducted concerning conditions of the Creative Commons Attribution (CC BY) license (https:// the awareness and lightning safety of the community, and it is important to conduct creativecommons.org/licenses/by/ awareness programs, and to make people aware of lightning hazards and the safety 4.0/). methods available for the public community [3,4]. Many countries collect lightning data

ISPRS Int. J. Geo-Inf. 2021, 10, 117. https://doi.org/10.3390/ijgi10030117 https://www.mdpi.com/journal/ijgi ISPRS Int. J. Geo-Inf. 2021, 10, 117 2 of 22

by using lightning locating systems and satellites, etc., and these data are used to analyze parametric information of lightning [5–7]. Moreover, lightning activities are not evenly distributed worldwide, and about 70% occur in the tropics, mostly over the land [8]. The characteristics and distribution of lightning flashes over Sri Lanka have been studied by researchers using the Lightning Imaging Sensor (LIS) data from Tropical Rain- fall Measurement Mission (TRMM) of National Aeronautics and Space Administration (NASA) [6,7,9–13]. Furthermore, as reported in [6], the lightning activities over Sri Lanka are gradually increasing. Moreover, lightning activities and the respective lightning safety levels have been analyzed over the places which are vulnerable to lightning incidents in Sri Lanka [6,7]. The information reported by these studies is critical to enhance the awareness of the lightning safety of the community, and to take appropriate actions to mitigate lightning hazards effectively. People living in developing countries in South Asia are vulnerable to lightning damage, and—in the Sri Lankan context—it is one of the severe natural hazards which cause impairments to property and people [14,15]. In general, antennas, wired network systems, etc. create an easy path for lightning strikes, and some activities—such as swimming, fishing, and walking in the open area during fatal lightning strikes—will increase the tendency of being victims of lightning hazards. Furthermore, Sri Lanka is experiencing several types of natural hazards, such as floods, strong winds, drought, heavy rain, and lightning, etc. [15,16]. As has been reported in previous studies, as a tropical country, hazards due to lightning have been identified as one of the dominant natural hazards in Sri Lanka [6,7,10–12,14–16]. However, due to a lack of detailed information on the distribution of lightning accidents in Sri Lanka, estimating the lightning hazard levels and performing a risk assessment in Sri Lanka are at a primary level. Many countries have already reported their lightning hazard information, such as how many people get killed or injured in a year due to lightning, and related statistical information [1,2]. However, in Sri Lanka, these estimations are yet to be reported, and one of the objectives of this study is to obtain a thorough statistical overview of lightning accidents in Sri Lanka. This paper reveals an analysis of lightning accidents in Sri Lanka from 1974 to 2019, with special attention to the geographical and temporal distribution of deaths, injuries, and property damage (residential houses) in Sri Lanka that occurred due to lightning. Moreover, the study has been extended in order to analyze the variations of lightning accidents monthly and climate season-wise, in response to the respective average lightning flash density of Sri Lanka in each month. The regional characteristics of lightning accidents in response to the respective average lightning flash density of each district were also analyzed. The lightning flash data available from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measurement Mission (TRMM) of NASA were used to generate the respective raster maps using geographic information systems (GIS), and the relevant average lightning flash densities were calculated using zonal statistics.

2. Data Collection The Disaster Management Centre (DMC) and the Department of Meteorology are the two organizations which are responsible for documenting weather-related hazards, deaths, and casualties in Sri Lanka. The database named the ‘Disaster Inventory System’ (DesInventar) is a database available from the Disaster Information Management System, which is maintained by the Disaster Management Centre (DMC), which includes the numerical details of the deaths, injuries, destroyed and damaged houses, and affected people, etc. in Sri Lanka [16,17]. The Disaster Management Centre (DMC) collects all of the information related to every disaster which occurs in Sri Lanka, such as animal attacks, floods, strong winds, fire, drought, heavy rain, and lightning, etc. They collected information about disasters from 1974 to 2006, with the aid of recorded information from several state organizations and published newspapers, etc. The relevant information after 2006 was collected using reported information with a certification of accuracy by the relevant regional officers in the area. Furthermore, the data possession phenomenon ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 3 of 25

ISPRS Int. J. Geo-Inf. 2021, 10, 117 mation about disasters from 1974 to 2006, with the aid of recorded information from sev-3 of 22 eral state organizations and published newspapers, etc. The relevant information after 2006 was collected using reported information with a certification of accuracy by the relevant regional officers in the area. Furthermore, the data possession phenomenon in dif- ferentin different sectors of sectors state organizations of state organizations has been hasestablished been established all over the all country, over the with country, diverse with arrangementsdiverse arrangements and formats. and Th formats.is detailed This information detailed was information deposited was into deposited the DisInventer into the databaseDisInventer by the database Disaster Management by the Disaster Centre Management (DMC) in Centre Sri Lanka. (DMC) For inthis Sri study, Lanka. detailed For this informationstudy, detailed on lightning-related information on incidents lightning-related from 1974 incidents to 2019, from which 1974 were to 2019,extracted which from were theextracted aforementioned from the database, aforementioned was used database, [16,17]. was used [16,17]. 3. Data Analysis 3. Data Analysis The geographical and temporal distributions of lightning deaths, injuries, and houses The geographical and temporal distributions of lightning deaths, injuries, and houses that were destroyed and damaged due to lightning activity were analyzed from 1974 to that were destroyed and damaged due to lightning activity were analyzed from 1974 to 2019 in Sri Lanka using ArcGIS 10.1 software. 2019 in Sri Lanka using ArcGIS 10.1 software. Sri Lanka, an island in the Indian Ocean, consists of nine provinces; they are further Sri Lanka, an island in the Indian Ocean, consists of nine provinces; they are further subdivided into 25 Administrative Districts (ADs), and each district is divided into several subdivided into 25 Administrative Districts (ADs), and each district is divided into several subdivisions named ‘Divisional Administrative Secretaries’. Altogether, the country is subdivisionsdivided into named 331 Divisional ‘Divisional Secretariat Administrative Divisions Secretaries’. (DSD). Figure Altogether,1 shows the the country geographical is di- videddistribution into 331 ofDivisional the existing Secretariat Provinces Divisi andons Administrative (DSD). Figure Districts1 shows (ADs)the geographical in Sri Lanka. distributionThe distribution of the existing of lightning Provinces accidents—such and Administrative as lightning Districts deaths, (ADs) injuries, in Sri and Lanka. damage The to distributionproperty—was of lightning analyzed acci ondents—such the level of theas existinglightning districts deaths, in injuries, the county. and damage to property—was analyzed on the level of the existing districts in the county.

FigureFigure 1. Existing 1. Existing provinces provinces and and administrative administrative districts districts (AD1-AD25) (AD1–AD25) in Sri in SriLanka. Lanka.

In Ina temporal a temporal distribution, distribution, the the lightning lightning accidents accidents were were analyzed analyzed annually annually and and sea- sea- sonally.sonally. The The results results were were used used to to identify identify the the maximum maximum and and minimum minimum regions andand periodsperi- odswhich which have have recorded recorded lightning lightning accidents accidents within within the the considered considered period period in in Sri Sri Lanka. Lanka. 4. Results 4. Results By analyzing the availability of 46-year data from 1974 to 2019, the geographical and temporal distribution of the recorded lightning accidents in Sri Lanka are presented together with their respective statistics. All of the administrative districts (ADs) are represented by relevant numbers (from AD 1–AD 25), as stated in Figure1.

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4.1. Temporal Distribution of the Lightning Accidents Due to the location of the country as an island in the equatorial and tropical zones, the Sri Lankan climate experiences vibrant variations during the 12 months in a year. According to the rainfall profile of Sri Lanka, there are four climate seasons, which classified as two monsoon seasons and two inter-monsoon seasons. The two monsoon seasons are named SWM-southwest monsoon season (May–September) and NEM-northeast monsoon season (December–February), whereas the two inter-monsoon seasons are distinguished as FIM-first inter-monsoon season (March–April) and SIM-second inter-monsoon season (October–November). Table1 shows the recorded number of deaths, injuries, destroyed houses, and damaged houses due to lightning activity in each AD during all four climate seasons, from 1974 to 2019. Figure2 shows the distribution of the deaths and injuries due to lightning accidents in Sri Lanka during all four climate seasons, from 1974 to 2019. Figure3 shows the distribution of damaged houses and destroyed houses due to lightning accidents in Sri Lanka during all four climate seasons, from 1974 to 2019. Stated below are the important observations that were extracted by referring to Figures2 and3.

Table 1. Lightning accidents in the administrative districts of Sri Lanka for all four climate seasons, from 1974 to 2019.

FIM SWM SIM NEM

District Deaths Deaths Deaths Deaths Injuries Injuries Injuries Injuries District Number Houses Damaged Houses Damaged Houses Damaged Houses Damaged Houses Destroyed Houses Destroyed Houses Destroyed Houses Destroyed

AD 1 Kandy 10 13 0 5 11 19 0 28 4 5 0 11 2 1 0 2 AD 2 Matale 4 7 0 2 2 1 0 1 1 0 0 0 0 0 0 0 AD 3 Nuwara Eliya 3 3 0 0 4 1 0 0 2 3 0 9 0 0 0 1 AD 4 Ampara 4 4 0 0 9 3 0 2 7 12 0 4 0 0 0 0 AD 5 Batticaloa 4 1 0 0 5 0 1 1 8 5 0 7 0 3 1 6 AD 6 Trincomalee 1 0 0 0 4 5 0 6 1 0 0 0 2 0 0 0 AD 7 Anuradhapura 8 1 0 15 15 16 0 1 7 0 0 0 1 2 0 0 AD 8 Polonnaruwa 15 64 0 0 19 3 4 0 3 5 3 2 3 3 0 1 AD 9 Jaffna 3 2 0 0 6 3 0 3 5 3 0 2 0 0 0 0 AD 10 Kilinochchi 1 0 0 0 5 13 1 4 1 0 0 0 1 0 0 0 AD 11 Mannar 1 2 0 2 0 0 1 2 0 1 0 0 0 0 0 0 AD 12 Mullaittivu 1 1 0 3 3 4 0 0 1 0 0 1 0 0 0 0 AD 13 Vavuniya 3 2 0 0 4 2 0 10 0 0 0 0 0 0 0 0 AD 14 Kurunegala 12 10 0 11 13 3 1 14 5 0 6 15 1 1 0 2 AD 15 Puttalam 11 4 0 6 2 2 0 6 12 12 0 22 1 0 1 3 AD 16 Kegalle 20 5 2 47 9 34 1 113 9 10 1 117 1 2 0 3 AD 17 Ratnapura 22 16 0 8 9 6 0 21 14 7 1 6 2 7 0 1 AD 18 Galle 12 13 0 7 4 21 0 14 5 0 0 6 6 2 0 1 AD 19 Hambantota 6 3 1 5 5 2 0 12 5 3 1 10 0 0 0 0 AD 20 Matara 13 0 0 2 0 4 0 6 2 3 0 6 2 12 0 0 AD 21 Badulla 10 6 1 25 7 3 1 5 6 13 0 6 2 4 0 1 AD 22 Moneragala 15 7 0 7 16 5 0 5 2 7 0 10 2 1 0 0 AD 23 Colombo 2 3 0 2 5 2 1 3 3 0 3 2 8 1 0 0 AD 24 Gampaha 10 16 0 7 13 1 1 16 5 1 0 10 3 2 0 0 AD 25 Kalutara 13 13 2 5 13 12 2 2 7 1 2 37 10 5 0 3 Total 204 196 6 159 183 165 14 275 115 91 17 283 47 46 2 24 ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 5 of 25

AD 16 Kegalle 20 5 2 47 9 34 1 113 9 10 1 117 1 2 0 3 AD 17 Ratnapura 22 16 0 8 9 6 0 21 14 7 1 6 2 7 0 1 AD 18 Galle 12 13 0 7 4 21 0 14 5 0 0 6 6 2 0 1 AD 19 Hambantota 6 3 1 5 5 2 0 12 5 3 1 10 0 0 0 0 AD 20 Matara 13 0 0 2 0 4 0 6 2 3 0 6 2 12 0 0 AD 21 Badulla 10 6 1 25 7 3 1 5 6 13 0 6 2 4 0 1 AD 22 Moneragala 15 7 0 7 16 5 0 5 2 7 0 10 2 1 0 0 AD 23 Colombo 2 3 0 2 5 2 1 3 3 0 3 2 8 1 0 0 AD 24 Gampaha 10 16 0 7 13 1 1 16 5 1 0 10 3 2 0 0 ISPRS Int. J. Geo-Inf. 2021, 10, 117 5 of 22 AD 25 Kalutara 13 13 2 5 13 12 2 2 7 1 2 37 10 5 0 3 Total 204 196 6 159 183 165 14 275 115 91 17 283 47 46 2 24

Figure 2. Lightning accidents in Sri Lanka during all four climate seasons, from 1974 to 2019 (a) number of deaths; ISPRSFigure Int. J. Geo-Inf. 2. Lightning 2020, 9, xaccidents FOR PEER in REVIEW Sri Lanka during all four climate seasons, from 1974 to 2019 (a) number of deaths; (b6) of 25 (b) number of injuries. number of injuries.

Figure 3. Lightning accidents in Sri Lanka during all four climate seasons, from 1974 to 2019: (a) number of damaged Figure 3. Lightning accidents in Sri Lanka during all four climate seasons, from 1974 to 2019: (a) number of damaged houses;houses; ( (bb)) number number of of destroyed destroyed houses. During the ﬁrst inter-monsoon season, from 1974 to 2019, there were 22 deaths; Moreover, in AD 3, AD 4, AD 5, AD 6, AD 8, AD 9, AD 10, and AD 13, there were no 20 deaths were recorded in AD 17 and AD 16, respectively, and the maximum number recorded incidents regarding destroyed and damaged houses due to lightning activities in the first inter-monsoon season during the considered period. In the southwest monsoon season, from 1974 to 2019, the maximum number of deaths—19 deaths—was recorded in AD 8, and the second maximum of 16 deaths due to lightning accidents was recorded in AD 22. There were no deaths recorded in AD 11 and AD 20 for this season. Furthermore, the maximum and second maximum of 34 and 21 injuries due to lightning accidents were recorded in AD 16 and AD 18, respectively, and there were no injuries recorded in AD 11 and AD 5 in the southwest monsoon season during the considered period. There were 113 houses damaged in AD 16, and four destroyed houses were recorded in AD 8 during the southwest monsoon season from 1974 to 2019, whereas, in both AD 3 and AD 12, there were no recorded events of destroyed and damaged houses. During the second inter-monsoon season, from 1974 to 2019, 14 deaths and 12 deaths were recorded in AD 17 and AD 15, respectively, and the maximum number of lightning injuries was recorded in AD 21, with a maximum record of 13 injuries followed by 12 injuries in AD 4 and AD15. The maximum number of damaged and destroyed houses due to lightning accidents in this season was recorded in AD 16 and AD 14, with 117 damaged houses and 6 destroyed houses, respectively. Moreover, AD 2, AD 6, AD 7, AD 10, AD 11, and AD 13 had no recorded incidents regarding destroyed and damaged houses due to lightning accidents. A maximum number of 10 deaths, and a second maximum of eight deaths were recorded in AD 25 and AD 23, respectively, during the northeast monsoon season, with a maximum record of 12 injuries recorded in AD 20. The maximum number of six damaged houses due to lightning accidents was recorded in AD 5 in this season. Meanwhile, only two administrative districts (AD 5 and AD 15) recorded destroyed houses in this season. In AD 2, AD 4, AD 9, AD 11, AD 12, AD 13, and AD 19, there were no recorded incidents regarding lightning accidents for people or houses in the northeast monsoon season during the considered period.

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of lightning injuries was recorded in AD 8, with a maximum record of 64 injuries. The maximum number of both destroyed and damaged houses due to lightning was recorded in AD 16 during this season. Moreover, in AD 3, AD 4, AD 5, AD 6, AD 8, AD 9, AD 10, and AD 13, there were no recorded incidents regarding destroyed and damaged houses due to lightning activities in the ﬁrst inter-monsoon season during the considered period. In the southwest monsoon season, from 1974 to 2019, the maximum number of deaths—19 deaths—was recorded in AD 8, and the second maximum of 16 deaths due to lightning accidents was recorded in AD 22. There were no deaths recorded in AD 11 and AD 20 for this season. Furthermore, the maximum and second maximum of 34 and 21 injuries due to lightning accidents were recorded in AD 16 and AD 18, respectively, and there were no injuries recorded in AD 11 and AD 5 in the southwest monsoon season during the considered period. There were 113 houses damaged in AD 16, and four destroyed houses were recorded in AD 8 during the southwest monsoon season from 1974 to 2019, whereas, in both AD 3 and AD 12, there were no recorded events of destroyed and damaged houses. During the second inter-monsoon season, from 1974 to 2019, 14 deaths and 12 deaths were recorded in AD 17 and AD 15, respectively, and the maximum number of lightning injuries was recorded in AD 21, with a maximum record of 13 injuries followed by 12 injuries in AD 4 and AD15. The maximum number of damaged and destroyed houses due to lightning accidents in this season was recorded in AD 16 and AD 14, with 117 damaged houses and 6 destroyed houses, respectively. Moreover, AD 2, AD 6, AD 7, AD 10, AD 11, and AD 13 had no recorded incidents regarding destroyed and damaged houses due to lightning accidents. A maximum number of 10 deaths, and a second maximum of eight deaths were recorded in AD 25 and AD 23, respectively, during the northeast monsoon season, with a maximum record of 12 injuries recorded in AD 20. The maximum number of six damaged houses due to lightning accidents was recorded in AD 5 in this season. Meanwhile, only two administrative districts (AD 5 and AD 15) recorded destroyed houses in this season. In AD 2, AD 4, AD 9, AD 11, AD 12, AD 13, and AD 19, there were no recorded incidents regarding lightning accidents for people or houses in the northeast monsoon season during the considered period.

4.2. Monthly Variation of Lightning Accidents Previous studies have shown that, in Sri Lanka, the maximum number of lightning activities occur in April, followed by the months of March, May, September, and October, which have more accidents than the other months in the year [7,10–12]. Table2 shows the monthly variation of the number of deaths, injuries, destroyed houses, and damaged houses due to lightning accidents in Sri Lanka from 1974 to 2019.

Table 2. Monthly variations of lightning accidents in Sri Lanka, from 1974 to 2019.

Number of Houses Number of Deaths Number of Injuries Month Destroyed Damaged No. % No. % No. % No. % January 14 2.6 3 0.6 0 0.0 2 0.3 February 14 2.6 32 6.4 0 0.0 11 1.5 March 54 9.8 49 9.8 2 5.1 14 1.9 April 150 27.3 147 29.5 4 10.3 145 19.6 May 91 16.6 96 19.3 10 25.6 151 20.4 June 22 4.0 12 2.4 1 2.6 26 3.5 July 16 2.9 15 3.0 1 2.6 11 1.5 August 18 3.3 16 3.2 0 0.0 24 3.2 September 36 6.6 26 5.2 2 5.1 63 8.5 October 62 11.3 51 10.2 8 20.5 150 20.2 November 53 9.7 40 8.0 9 23.1 133 17.9 December 19 3.5 11 2.2 2 5.1 11 1.5 Total 549 100 498 100 39 100 741 100 ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 7 of 25

4.2. Monthly Variation of Lightning Accidents Previous studies have shown that, in Sri Lanka, the maximum number of lightning activities occur in April, followed by the months of March, May, September, and October, which have more accidents than the other months in the year [7,10–12]. Table 2 shows the monthly variation of the number of deaths, injuries, destroyed houses, and damaged houses due to lightning accidents in Sri Lanka from 1974 to 2019.

Table 2. Monthly variations of lightning accidents in Sri Lanka, from 1974 to 2019. Number of Number of In- Number of Houses Month Deaths juries Destroyed Damaged No. % No. % No. % No. % January 14 2.6 3 0.6 0 0.0 2 0.3 February 14 2.6 32 6.4 0 0.0 11 1.5 March 54 9.8 49 9.8 2 5.1 14 1.9 April 150 27.3 147 29.5 4 10.3 145 19.6 May 91 16.6 96 19.3 10 25.6 151 20.4 June 22 4.0 12 2.4 1 2.6 26 3.5 July 16 2.9 15 3.0 1 2.6 11 1.5 August 18 3.3 16 3.2 0 0.0 24 3.2 September 36 6.6 26 5.2 2 5.1 63 8.5 October 62 11.3 51 10.2 8 20.5 150 20.2 November 53 9.7 40 8.0 9 23.1 133 17.9 ISPRS Int. J. Geo-Inf. 2021, 10, 117 December 19 3.5 11 2.2 2 5.1 11 1.5 7 of 22 Total 549 100 498 100 39 100 741 100

Figure4 illustratesFigure a graphical 4 illustrates overview a graphical of the overview monthly of variation the monthly of the variation information of the information tabulated 180 intabulated Table2. 180 in Table 2.

Figure 4. FigureMonthly 4. Monthly variation variation of lightning of lightning accidents acci indents Sri Lanka in Sri from Lanka 1974 from to 2019.1974 to 2019.

4.3. Geographical4.3. Distribution Geographical of LightningDistribution Accidents of Lightning Accidents Table3 shows theTable total 3 numbershows the of total lightning number accidents of lightning in all ac 25cidents administrative in all 25 administrative districts districts (ADs) in Sri Lanka,(ADs) from in Sri 1974 Lanka, to 2019, from whereas 1974 to Figure 2019,5 whereasshows the Figure total number5 shows ofthe lightning total number of light- accidents by theirning percentage accidents variationby their percentage for all 25 ADs variat forion the for same all 25 period. ADs for the same period. As indicated in Table 3 and Figure 5, 47 deaths was recorded in the Ratnapura district Table 3. Recorded number of lightning(AD 17) accidents and 43 in deaths each administrative was recorded district, in the fromKalu 1974tara todistrict 2019. (AD 25), i.e., 8.6% and 7.8% Number of Number of Number of Houses District District Deaths Injuries Destroyed Damaged Number No. % No. % No. % No. %

AD 1 Kandy 27 4.9 38 7.6 0 0.0 46 6.2 AD 2 Matale 7 1.3 8 1.6 0 0.0 3 0.4 AD 3 Nuwara Eliya 9 1.6 7 1.4 7 17.9 10 1.3 AD 4 Ampara 20 3.6 19 3.8 0 0.0 6 0.8 AD 5 Batticaloa 17 3.1 9 1.8 2 5.1 14 1.9 AD 6 Trincomalee 8 1.5 5 1.0 0 0.0 6 0.8 AD 7 Anuradhapura 31 5.6 19 3.8 0 0.0 16 2.2 AD 8 Polonnaruwa 40 7.3 75 15.1 0 0.0 3 0.4 AD 9 Jaffna 14 2.6 8 1.6 0 0.0 5 0.7 AD 10 Kilinochchi 8 1.5 13 2.6 1 2.6 4 0.5 AD 11 Mannar 1 0.2 3 0.6 1 2.6 4 0.5 AD 12 Mullaittivu 5 0.9 5 1.0 0 0.0 4 0.5 AD 13 Vavuniya 7 1.3 4 0.8 0 0.0 10 1.3 AD 14 Kurunegala 31 5.6 14 2.8 7 17.9 42 5.7 AD 15 Puttalam 26 4.7 18 3.6 1 2.6 37 5.0 AD 16 Kegalle 39 7.1 51 10.2 4 10.3 280 37.8 AD 17 Ratnapura 47 8.6 36 7.2 1 2.6 36 4.9 AD 18 Galle 27 4.9 36 7.2 0 0.0 28 3.8 AD 19 Hambantota 16 2.9 8 1.6 2 5.1 27 3.6 AD 20 Matara 17 3.1 19 3.8 0 0.0 14 1.9 AD 21 Badulla 25 4.6 26 5.2 2 5.1 37 5.0 AD 22 Moneragala 35 6.4 20 4.0 0 0.0 22 3.0 AD 23 Colombo 18 3.3 6 1.2 4 10.3 7 0.9 AD 24 Gampaha 31 5.6 20 4.0 1 2.6 33 4.5 AD 25 Kalutara 43 7.8 31 6.2 6 15.4 47 6.3 ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 8 of 25

respectively from the overall point of view. During the period from 1974 to 2019, only one death happened in the Mannar district (AD 11). Furthermore, within the considered period, the maximum and second maximum of the injuries due to lightning accidents were recorded in the Polonnaruwa district (AD 8) and Kegalle district (AD 16), i.e., 15.1% and 10.2% respectively. There were two administrative districts (AD 11 and AD 13) with a minimum number of lightning injuries during the period from 1974 to 2019, with less than 1% in each district. There were 280 houses (37.8%) damaged due to lightning accidents in the Kegalle district (AD 16), and the minimum number of houses (three) damaged due to lightning accidents was recorded in the Polonnaruwa district (AD 8) and the Matale district (AD 2). Moreover, the maximum number of destroyed houses (seven) due to lightning accidents was recorded in the Nuwara Eliya (AD 3) and Kurunegala (AD 14) districts. Although some damaged houses were recorded due to lightning activity in almost all of ISPRS Int. J. Geo-Inf. 2021, 10, 117 the administrative districts, there were no destroyed houses recorded in twelve of the8 Ad- of 22 ministrative Districts (AD 1, AD 2, AD 4, AD 6, AD 7, AD 8, AD 9, AD 12, AD 13, AD 18, AD 20, and AD 22).

FigureFigure 5. 5. VariationsVariations of of the the lightning lightning accidents in all 25 administ administrativerative districts (ADs) in Sri Lanka, from 1974 to 2019.

Table 3. Recorded numberAs indicated of lightning in Tableaccidents3 and in Figureeach administrative5, 47 deaths wasdistrict, recorded from 1974 in the to 2019. Ratnapura district (AD 17) and 43 deaths was recorded in the Kalutara district (AD 25), i.e., 8.6% and 7.8% Number of Number of Number of Houses District respectively from the overall point of view. During the period from 1974 to 2019, only oneDistrict death happenedDeaths in the MannarInjuries district (ADDestroyed 11). Furthermore, Damaged within the considered Number period, the maximumNo. and% second No. maximum % ofNo. the injuries% dueNo. to lightning% accidents were recorded in the Polonnaruwa district (AD 8) and Kegalle district (AD 16), i.e., 15.1% and AD 1 Kandy10.2% respectively. 27 There4.9 were 38 two administrative7.6 0 0.0 districts 46 (AD 116.2 and AD 13) with a AD 2 Mataleminimum number 7 of lightning1.3 injuries8 1.6 during the0 period0.0 from3 19740.4 to 2019, with less than AD 3 Nuwara1% in each Eliya district. 9 There1.6 were 2807 houses1.4 (37.8%)7 damaged17.9 10 due to1.3 lightning accidents in the Kegalle district (AD 16), and the minimum number of houses (three) damaged due to AD 4 Amparalightning accidents 20 was recorded3.6 19 in the3.8 Polonnaruwa 0 district0.0 (AD 6 8) and0.8 the Matale district AD 5 Batticaloa(AD 2). Moreover, 17 the maximum3.1 9 number1.8 of destroyed2 5.1 houses14 (seven)1.9 due to lightning AD 6 Trincomaleeaccidents was recorded 8 1.5 in the Nuwara5 1.0 Eliya 0 (AD 3)0.0 and Kurunegala6 0.8 (AD 14) districts. Although some damaged houses were recorded due to lightning activity in almost all AD 7 Anuradhapuraof the administrative 31 districts,5.6 there19 were3.8 no destroyed 0 0.0 houses16 recorded2.2 in twelve of the AD 8 PolonnaruwaAdministrative Districts 40 7.3 (AD 1,75 AD 2,15.1 AD 4, AD0 6, AD 0.0 7, AD 3 8, AD 0.4 9, AD 12, AD 13, AD 18, AD 20, and AD 22). AD 9 Jaffna 14 2.6 8 1.6 0 0.0 5 0.7 AD 10 Kilinochchi4.4. Statistical Analysis 8 of 1.5 the Lightning13 Accidents2.6 1 2.6 4 0.5 AD 11 MannarIn order to present 1 a0.2 general 3 overview 0.6 of the1 lightning2.6 accidents4 0.5 recorded in Sri Lanka from 1974 to 2019, a comprehensive statistical analysis was carried out. Tables4 and5 AD 12 Mullaittivu 5 0.9 5 1.0 0 0.0 4 0.5 show the respective statistics of the monthly variation of lightning accidents—covering AD 13 Vavuniyadeaths, injuries, and 7 property1.3 damage—calculated4 0.8 0 from0.0 the recorded10 1.3 incidents in Sri Lanka AD 14 Kurunegalafrom 1974 to 2019 31 whereas 5.6 Tables14 A1 and2.8 A2 show 7 the17.9 respective 42 statistics5.7 at the district level. As indicated in Table4, the maximum number of deaths was recorded in April, AD 15 Puttalam 26 4.7 18 3.6 1 2.6 37 5.0 with an average of 3.26 deaths, followed by 1.98 deaths in May, whereas in January and February it was 0.30 deaths, which are the lowest. As per the information stated in Table4 , in general, there could be at least one death due to lightning accidents in March, April, May, October, and November. Moreover, a maximum number of injuries was recorded in

April, with an average of 3.20 injuries, followed by 2.09 injuries in May; in January, there were 0.07 injuries at the lowest. Furthermore, it can be stated that there was at least one injury due to lightning accidents in March, April, May, and October. ISPRS Int. J. Geo-Inf. 2021, 10, 117 9 of 22

Table 4. Statistics of the monthly variations of deaths and injuries in Sri Lanka due to lightning, from 1974 to 2019.

Number of Deaths Number of Injuries Month Standard Standard Average Maximum Minimum Average Maximum Minimum Deviation Deviation January 0.30 2 0 0.66 0.07 2 0 0.33 February 0.30 4 0 0.84 0.70 16 0 2.93 March 1.17 8 0 1.90 1.07 13 0 2.64 April 3.26 29 0 4.83 3.20 61 0 9.31 May 1.98 10 0 2.34 2.09 17 0 4.03 June 0.48 4 0 0.98 0.26 2 0 0.61 July 0.35 5 0 0.90 0.33 10 0 1.49 August 0.39 3 0 0.83 0.35 6 0 1.20 September 0.78 7 0 1.49 0.57 11 0 1.73 October 1.35 16 0 2.72 1.11 13 0 2.71 November 1.15 10 0 1.89 0.87 11 0 2.17 December 0.41 4 0 0.88 0.24 3 0 0.79

Table 5. Statistics of the monthly variations of property damage in Sri Lanka due to lightning, from 1974 to 2019.

Number of Houses Destroyed Number of Houses Damaged Standard Standard Average Maximum Minimum Average Maximum Minimum Deviation Deviation January 0.00 0 0 0.00 0.04 1 0 0.21 February 0.00 0 0 0.00 0.24 8 0 1.20 March 0.04 1 0 0.21 0.30 4 0 0.81 April 0.09 2 0 0.35 3.15 38 0 8.00 May 0.22 5 0 0.81 3.28 84 0 12.82 June 0.02 1 0 0.15 0.57 12 0 2.20 July 0.02 1 0 0.15 0.24 5 0 0.82 August 0.00 0 0 0.00 0.52 14 0 2.23 September 0.04 1 0 0.21 1.37 29 0 4.95 October 0.17 5 0 0.77 3.26 83 0 0 November 0.20 3 0 0.58 2.89 64 0 10.20 December 0.04 2 0 0.29 0.24 6 0 0.97

As indicated in Table5, throughout the study period, the average number of destroyed houses in any month is insigniﬁcant, with a maximum calculated value of 0.22, whereas the average number of damaged houses is approximately three damaged in April, May, October, and November. The calculated statistical overview of the recorded lightning accidents in terms of annual variation is shown in Table6. Accordingly, for the study period from 1974 to 2019 (46 years), the average number of deaths and injuries in a year could be reported as 11.93 (maximum = 68, minimum = 0, and standard deviation = 11.28) and 10.83 (maximum = 67, minimum = 0, and standard deviation = 12.22), respectively. However, the average number of deaths in a year from 2019, for the last 40 years, 30 years, 20 years, and 10 years, could be reported as 12.90, 15.73, 18.40, and 23.20, respectively, whereas the average number of injuries could be reported as 11.53, 13.57, 16.50, and 18.00. Furthermore, the average number of destroyed houses due to lightning in a year for the study period from 1974 to 2019 is 0.85 (maximum = 6, minimum = 0, and standard deviation = 1.62) whereas the average number of damaged houses is 16.11 (maximum = 245, minimum = 0, and standard deviation = 46.00). ISPRS Int. J. Geo-Inf. 2021, 10, 117 10 of 22

Table 6. Statistical overview of the lightning accidents reported in Sri Lanka, from 1974 to 2019.

Nature of Accidents Range Statistics Number of Deaths Number of Injuries Number of Houses Destroyed Number of Houses Damaged Mean 11.93 10.83 0.85 16.11 1974–2019 Maximum 68 67 6 245 (46 years) Minimum 0 0 0 0 Standard Deviation 11.28 12.22 1.62 46.00 Mean 12.90 11.53 0.98 18.50 1980–2019 Maximum 68 67 6 245 (40 years) Minimum 0 0 0 0 Standard Deviation 11.73 12.78 1.70 48.96 Mean 15.73 13.57 1.27 23.83 1990–2019 Maximum 68 67 6 245 (30 years) Minimum 2 0 0 0 Standard Deviation 12.25 13.76 1.87 55.67 Mean 18.40 16.50 1.90 35.30 2000–2019 Maximum 68 67 6 245 (20 years) Minimum 5 0 0 0 Standard Deviation 13.22 15.27 2.02 65.67 Mean 23.20 18.00 2.00 57.30 2010–2019 Maximum 68 36 6 245 (10 years) Minimum 9 7 0 0 Standard Deviation 16.33 10.07 2.21 88.43

As reported in [18], the population of Sri Lanka was 20.36 million in 2012, and with the reported population growth rate of 0.7%, the population of Sri Lanka would be 21.38 million by 2019. Therefore, by considering the average number of deaths reported in this study during the period from 1974 to 2019, in Sri Lanka, 0.56 people per million per year were killed by lightning, whereas 0.51 people per million per year were injured. However, by considering the reported accidents from 2000 to 2019, 0.86 people per million per year were killed, and 0.77 people per million per year were injured, which is a significant increase. Table7 shows the seasonal variations of the lightning accidents in Sri Lanka that occurred, covering all four climate seasons from 1974 to 2019, whereas Figure6 illustrates the graphical overview of the same, as generated by referring to Table1. According to previous studies, the seasonal variation of the lightning activities shows that the maximum lightning activities happen in the ﬁrst inter-monsoon season, followed to a greater extent by the second inter-monsoon season than the other two seasons [7,10–12]. The variation pattern observed in this study for the lightning accidents in Sri Lanka, as shown in Table7 and Figure6, is also overlaid with the aforementioned seasonal variation pattern of the lightning activities. The calculated statistics of the seasonal variations of lightning accidents in Sri Lanka, from 1974 to 2019, are tabulated in Table8.

Table 7. Seasonal variations of lightning accidents in Sri Lanka, from 1974 to 2019.

Number of Number of Number of Houses Deaths Injuries Destroyed Damaged No. % No. % No. % No. % FIM 204 37.2 196 39.4 6 15.4 159 21.5 SWM 183 33.3 165 33.1 14 35.9 275 37.1 SIM 115 20.9 91 18.3 17 43.6 283 38.2 NEM 47 8.6 46 9.2 2 5.1 24 3.2 ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 12 of 25

Deaths Injuries Destroyed Damaged No. % No. % No. % No. % FIM 204 37.2 196 39.4 6 15.4 159 21.5 SWM 183 33.3 165 33.1 14 35.9 275 37.1 SIM 115 20.9 91 18.3 17 43.6 283 38.2 NEM 47 8.6 46 9.2 2 5.1 24 3.2

Table 8. Statistics of the seasonal variations of lightning accidents in Sri Lanka, from 1974 to 2019. Deaths Deaths Injured Houses Destroyed Damaged Houses Deaths Injured Houses Destroyed Damaged Houses

Mean 2.22 2.13 0.07 1.73 0.80 0.72 0.06 1.20 Maximum 29 61 2 38 10 17 5 84 FIM

Minimum 0 0 0 0 0 0 0 0 SWM Standard Deviation 3.80 6.89 0.29 5.83 1.54 2.25 0.39 6.36 Mean 1.25 0.99 0.18 3.08 0.44 0.56 0.01 0.25 Maximum 16 13 5 83 14 32 2 11 SIM SIM Minimum 0 0 0 0 0 0 0 0 NEM StandardISPRS Deviation Int. J. Geo-Inf. 20212.33, 10, 117 2.44 0.68 11.56 1.40 3.21 0.17 1.28 11 of 22

Figure 6. Graphical overview of the seasonal variations of lightning accidents in Sri Lanka, from Figure 6. Graphical overview of the seasonal variations of lightning accidents in Sri Lanka, from 1974 to 2019. 1974 to 2019.

Table 8. TheStatistics maximum of the number seasonal of variations deaths of(204 lightning deaths; accidents average in = Sri 2.22, Lanka, maximum from 1974 = to29, 2019. minimum = 0, and standard deviationHouses = 3.80)Houses and injuries (196 injured people; averageHouses = 2.13,Houses Deaths Injured Deaths Injured maximum = 61, minimumDestroyed = 0, and Damagedstandard deviation = 6.89) was recordedDestroyed in the firstDamaged Mean inter-monsoon2.22 season 2.13 during 0.07 the considered 1.73 period, with0.80 37.2 % 0.72 deaths and 0.06 39.4 % in- 1.20 Maximum 29 61 2 38 10 17 5 84 jured people from the overall point of view. TheFIM second maximum of the deaths (33.3 %) SWM Minimum 0 0 0 0 0 0 0 0 Standard Deviationand injuries3.80 (33.1 6.89 %) was recorded 0.29 in the 5.83 southwest monsoon 1.54 season. 2.25 However, 0.39 the max- 6.36 Mean imum number1.25 of 0.99 destroyed 0.18 houses (173.08 houses; average =0.44 0.18, maximum 0.56 = 5, 0.01 minimum 0.25= Maximum 0, and standard16 deviation 13 = 0.68) 5 and damaged 83 houses (283 14 houses; 32 average = 2 3.08, maxi- 11 SIM NEM Minimum mum = 83,0 minimum 0 = 0, and 0 standard deviation 0 = 11.56) was 0 recorded 0 in the second 0 inter- 0 Standard Deviation 2.33 2.44 0.68 11.56 1.40 3.21 0.17 1.28 monsoon season, with 43.6 % and 38.2 %, respectively, from the overall point of view.

The maximum number of deaths (204 deaths; average = 2.22, maximum = 29, minimum = 0, and standard deviation = 3.80) and injuries (196 injured people; average = 2.13, maximum = 61, minimum = 0, and standard deviation = 6.89) was recorded in the ﬁrst inter-monsoon season during the considered period, with 37.2% deaths and 39.4% injured people from the overall point of view. The second maximum of the deaths (33.3%) and injuries (33.1%) was recorded in the southwest monsoon season. However, the maximum number of destroyed houses (17 houses; average = 0.18, maximum = 5, minimum = 0, and standard deviation = 0.68) and damaged houses (283 houses; average = 3.08, maximum = 83, minimum = 0, and standard deviation = 11.56) was recorded in the second inter-monsoon season, with 43.6% and 38.2%, respectively, from the overall point of view. Noticeably, the minimum number of deaths (47 deaths; average = 0.44, maximum = 14, minimum = 0, and standard deviation = 31.40), injuries (46 injured people; average = 0.56, maximum = 32, minimum = 0, and standard deviation = 3.21), destroyed houses (2 houses; average = 0.01, maximum = 2, minimum = 0, and standard deviation = 0.17), and damaged houses (24 houses; average = 0.25, maximum = 11, minimum = 0, and standard deviation = 1.28) due to lightning accidents occurred in the northeast monsoon season, with 8.6%, 9.2%, 5.1%, and 3.2%, respectively, within the considered period. Figure7 shows the annual variation of the lightning accidents in Sri Lanka, from 1974 to 2019. According to Figure7, the maximum number of 68 people died due to lightning accidents in 2012, and the maximum number of 67 people were injured due to lightning accidents in 2008. A maximum of six houses were destroyed due to lightning activity in 2016 and 2018. Furthermore, a maximum of 245 houses were damaged due to lightning activity in 2019, and the second maximum of 199 damaged houses was recorded in 2018 within the considered period. ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 13 of 25

Noticeably, the minimum number of deaths (47 deaths; average = 0.44, maximum = 14, minimum = 0, and standard deviation = 31.40), injuries (46 injured people; average = 0.56, maximum = 32, minimum = 0, and standard deviation = 3.21), destroyed houses (2 houses; average = 0.01, maximum = 2, minimum = 0, and standard deviation = 0.17), and damaged houses (24 houses; average = 0.25, maximum = 11, minimum = 0, and standard deviation = 1.28) due to lightning accidents occurred in the northeast monsoon season, with 8.6 %, 9.2 %, 5.1 %, and 3.2 %, respectively, within the considered period. Figure 7 shows the annual variation of the lightning accidents in Sri Lanka, from 1974 to 2019. According to Figure 7, the maximum number of 68 people died due to lightning accidents in 2012, and the maximum number of 67 people were injured due to lightning accidents in 2008. A maximum of six houses were destroyed due to lightning activity in

ISPRS Int. J. Geo-Inf. 2021, 10, 1172016 and 2018. Furthermore, a maximum of 245 houses were damaged due to12 lightning of 22 activity in 2019, and the second maximum of 199 damaged houses was recorded in 2018 within the considered period.

FigureFigure 7. Annual 7. Annual variation variation of of the the lightning lightning acci accidentsdents inin Sri Sri Lanka, Lanka, from from 1974 1974 to 2019.to 2019.

FigureFigure 8 8shows shows the the cumulative cumulative numbernumber of of lightning lightning accidents accidents reported reported in Sri in Lanka, Sri Lanka, fromfrom 1974 1974 to to2019. 2019. As As can can be be seen seen in in Figure8 ,8, other other than than the the destroyed destroyed number number of houses, of houses, the numbers of deaths, injuries, and damaged houses have shown an incremental trend, the numbers of deaths, injuries, and damaged houses have shown an incremental trend, moving towards 2019 from 1974. Moreover, according to Figure8, it can be observed that movingthe reported towards accidents 2019 from during 1974. the Moreover, last 20 years accord (2000–2019)ing to Figure are signiﬁcantly 8, it can be higher observed than that thethose reported reported accidents from 1974 during to 1999 the (26 last years). 20 ye Accordingly,ars (2000–2019) as indicated are significantly in Figure9, higher for the than thosestudy reported period from considered—from 1974 to 1999 1974 (26 toyears). 2019—67.03% Accordingly, of the deaths,as indicated 66.27% in of Figure the injuries, 9, for the ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER97.44% REVIEW of the destroyed houses, and 95.28% of the damaged houses were reported during14 of 25 study period considered—from 1974 to 2019—67.03 % of the deaths, 66.27 % of the injuries,the 97.44 last 20% yearsof the (from destroyed 2000 to houses, 2019). and 95.28 % of the damaged houses were reported during the last 20 years (from 2000 to 2019).

FigureFigure 8. Cumulative 8. Cumulative lightning lightning accidents accidents in Sri in Sri Lanka, Lanka, from from 1974 1974 to to 2019: 2019: ( (aa)) number number of deaths;deaths; ( b(b)) number number of of injuries; injuries; (c) number(c) numberof destroyed of destroyed houses; houses; (d) number (d) number of damaged of damaged houses. houses.

Figure 9. Cumulative lightning accidents (in %) in Sri Lanka, from 1974 to 2019.

With regard to the reported lightning accidents, there was a significant increase in the number of deaths, injuries, and property damage in the last two decades. This could be due to the population growth of Sri Lanka during the last few decades, and urbanization. On the other hand, even though there were no incidents recorded on the number of destroyed houses in most of the years in the past, few incidents were recorded in recent years that caused houses to be destroyed. As the population grows, unused landmasses in the country are dwindling at a rapid rate due to the demand for cultivation or housing projects. This could have been a possible reason for such an increase in lightning accidents. However, it is important to mention that the population growth rate has been on a decline since 1974 [18]. Therefore, further investigations are recommended in this regard. Tall buildings and metal structures could be the more dominant constructions at present than in the past, due to urbanization. Furthermore, the usage of sensitive household electrical and electronic devices has increased rapidly with urbanization during the last few decades in the country. Therefore, the tendency of lightning accidents happening to household equipment could have also been increased. Moreover, without having properly coordinated lightning protection systems, they may be vulnerable lightning accidents from

ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 14 of 25

ISPRS Int. J. Geo-Inf. 2021, 10, 117 13 of 22 Figure 8. Cumulative lightning accidents in Sri Lanka, from 1974 to 2019: (a) number of deaths; (b) number of injuries; (c) number of destroyed houses; (d) number of damaged houses.

FigureFigure 9. 9. CumulativeCumulative lightning lightning accidents accidents (in (in %) %) in in Sri Sri Lanka, Lanka, from from 1974 1974 to to 2019. 2019.

WithWith regard regard to thethe reportedreported lightninglightning accidents, accidents, there there was was a signiﬁcanta significant increase increase in thein thenumber number of deaths, of deaths, injuries, injuries, and and property property damage damage in the in last the two last decades. two decades. This could This becould due beto due the populationto the population growth growth of Sri Lanka of Sri duringLanka during the last the few last decades, few decades, and urbanization. and urbaniza- On tion.the otherOn the hand, other even hand, though even there though were there no incidentswere no incidents recorded recorded on the number on the of number destroyed of destroyedhouses in houses most of in the most years of inthe the years past, in fewthe incidentspast, few wereincidents recorded were inrecorded recent yearsin recent that yearscaused that houses caused to behouses destroyed. to be Asdestroyed. the population As the grows,population unused grows, landmasses unused in landmasses the country inare the dwindling country are at adwindling rapid rate at due a rapid to the rate demand due to for the cultivation demand for or cultivation housing projects. or housing This projects.could have This been could a have possible been reason a possible for such reason an for increase such an in increase lightning in accidents.lightning accidents. However, However,it is important it is important to mention to mention that the that population the population growth growth rate has rate been has onbeen a decline on a decline since since1974 [197418]. Therefore,[18]. Therefore, further further investigations investig areations recommended are recommended in this regard. in this Tallregard. buildings Tall buildingsand metal and structures metal structures could be could the more be the dominant more dominant constructions constructions at present at present than in than the inpast, the duepast, to due urbanization. to urbanization. Furthermore, Furthermore, the usage the usage of sensitive of sensitive household household electrical electrical and andelectronic electronic devices devices has has increased increased rapidly rapidly with with urbanization urbanization during during the the last last few few decades dec- adesin the in country.the country. Therefore, Therefore, the tendencythe tendency of lightning of lightning accidents accidents happening happening to householdto house- holdequipment equipment could could have alsohave been also increased.been increa Moreover,sed. Moreover, without without having properlyhaving properly coordinated co- ordinatedlightning lightning protection protection systems, systems, they may they be vulnerablemay be vulnerable lightning lightning accidents accidents from a directfrom lightning hit, a side ﬂash, and a step potential rise, or due to a high induced voltage on the relevant low-voltage transmission lines.

5. Discussion This study was oriented towards the analysis of the distribution of lightning accidents in Sri Lanka, covering the period of 1974 to 2019. There were 549 deaths, 498 injured people, 39 destroyed houses, and 741 damaged houses recorded in total during the aforementioned 46-year period due to the lightning activities over the land area covered by the island. The aforementioned results of lightning accidents over Sri Lanka are vital to the identification of the high-risk periods in a calendar year, as well as hotspots, by using a spatiotemporal variation of lightning accidents over Sri Lanka. Figure 10 shows the spatial annual variation of the lightning flash density in Sri Lanka generated using GIS, and the recorded number of total lightning accidents in the percentage-wise distribution in the Districts and Provinces for the period from 1974 to 2019. The lightning flash data which was collected by the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measurement Mission (TRMM) of NASA, from 1998 to 2014, and were used to calculate the lightning flash density (flashes km-2 year−1) over Sri Lanka and the surrounding coastal belt, in a similar way to that used in previously reported studies [6,7,10,12]. The lightning flash density was presented by the respective 0.20 × 0.20 latitude and longitude grids. This shows a direct relationship between the lightning flash density and the recorded number of lightning accidents over Sri Lanka. As can be observed in Figure 10a,b, ADs with higher lightning flash densities are highly vulnerable to lightning hazards, whilst the provincial-wise view also shows the same trend, as illustrated in Figure 10c,d. Furthermore, according to Figure 10, the administrative districts and ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 15 of 25

a direct lightning hit, a side flash, and a step potential rise, or due to a high induced voltage on the relevant low-voltage transmission lines.

5. Discussion This study was oriented towards the analysis of the distribution of lightning accidents in Sri Lanka, covering the period of 1974 to 2019. There were 549 deaths, 498 injured people, 39 destroyed houses, and 741 damaged houses recorded in total during the aforementioned 46-year period due to the lightning activities over the land area covered by the island. The aforementioned results of lightning accidents over Sri Lanka are vital to the identification of the high-risk periods in a calendar year, as well as hotspots, by using a spatiotemporal variation of lightning accidents over Sri Lanka. Figure 10 shows the spatial annual variation of the lightning flash density in Sri Lanka generated using GIS, and the recorded number of total lightning accidents in the percentage-wise distribution in the Districts and Provinces for the period from 1974 to 2019. The lightning flash data which was collected by the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measurement Mission (TRMM) of NASA, from 1998 to 2014, and were used to calculate the lightning flash density (flashes km-2 year-1) over Sri Lanka and the surrounding coastal belt, in a similar way to that used in previously reported studies [6,7,10,12]. The lightning flash density was presented by the respective 0.20 × 0.20 latitude and longitude grids. This shows a direct relationship between the lightning flash density and the recorded number of lightning accidents over Sri Lanka. As can be observed in ISPRS Int. J. Geo-Inf. 2021, 10, 117 Figures 10a and 10b, ADs with higher lightning flash densities are highly vulnerable14 of 22 to lightning hazards, whilst the provincial-wise view also shows the same trend, as illustrated in Figures 10c and 10d. Furthermore, according to Figure 10, the administrative districtsprovinces and with provinces lower lightningwith lower ﬂash lightning densities flash are also densities show relatively are also lowshow numbers relatively of low numberslightning of accidents. lightning There accidents. was a maximum There was of 15.7%a maximum deaths, 18.9%of 15.7 injuries, % deat 28.2%hs, 18.9 destroyed % injuries, 28.2houses, % destroyed and 42.6% houses, damaged and houses 42.6 recorded% damage in thed houses Sabaragamuwa, recorded Northwest, in the Sabaragamuwa, Western, Northwest,and Sabaragamuwa Western, provinces,and Sabaraga respectively.muwa provinces, respectively.

FigureFigure 10. Annual 10. Annual variation variation of lightning of lightning flash ﬂash density density with with the recordedrecorded lightning lightning accidents accidents (in %)(in in%) Sri in Lanka, Sri Lanka, from from 1974 1974 to 2019:to 2019: (a) deaths (a) deaths and and injuries injuries according according to to districts; districts; ( (b) propertyproperty damage damage according according to districts;to districts; (c) deaths (c) deaths and injuriesand injuries accordingaccording to provinces; to provinces; (d) (propertyd) property damage damage according according toto provinces.provinces.

Similarly,Similarly, Figure Figure 1111 shows thethe spatialspatial variation variation of of the the lightning lightning flash flash density density in Sri in Sri Lanka,Lanka, and and the the recorded recorded numbernumber of of total total lightning lightning accidents accidents in the in percentage-wise the percentage-wise distri- dis- bution for all four climate seasons. Even though a higher lightning flash density dominated tribution for all four climate seasons. Even though a higher lightning flash density domi- in the first inter-monsoon season, together with a significant record of lightning accidents natedcompared in the to first the otherinter-monsoon three climate season, seasons, together lightning with accidents a significant were recorded record throughout of lightning accidentsthe country compared in all four to climate the other seasons. three Figure climate 12 showsseasons, the lightning spatial variation accidents of the were lightning recorded throughoutflash density thein country Sri Lanka, in all and four the climate recorded seasons. number Figure of total 12 deaths shows and the injuries spatial in variation the percentage-wise distribution during all 12 months, whereas Figure 13 shows the spatial variation of the lightning flash density in Sri Lanka and the recorded number of damaged properties. The statistical details of the lightning flash density in Sri Lanka—extracted from the

aforementioned raster maps using zonal statistics—are tabulated in AppendixA: Table A3, Table A4, Table A5, and Table A6. As stated in Table A3, the annual average lightning flash density of Sri Lanka is 8.26 flashes km−2 year−1 (maximum = 28.05, minimum = 0.84, and standard deviation = 3.88). As stated in Table A4, the highest lightning flash density of Sri Lanka is in April (average = 31.33 flashes km−2 year−1, maximum = 146.76, minimum = 0.02, and standard deviation = 23.31), whereas January recorded the minimum (average = 2.00 flashes km−2 year−1, maximum = 22.78, minimum = 0.00, and standard deviation = 3.84). As stated in Table A5, with regards to the climate seasons, the highest lightning flash density of Sri Lanka was reported in the first inter-monsoon season (average = 22.25 flashes km-2 year-1, maximum = 85.88, minimum = 0.79, and standard deviation = 15.09). Moreover, as stated in Table A6, the Kegalle district recorded the highest lightning flash density (average = 17.27 flashes km−2 year−1, maximum = 27.19, minimum = 7.53, and standard deviation = 3.39), whereas the Jaffna district recorded the lowest (average = 1.87 flashes km−2 year−1, maximum = 3.01, minimum = 0.84, and standard deviation = 0.45). The variations of the average lightning flash densities in terms of months, districts, and seasons are shown in Figure4, Figure5, and Figure7, respectively, together with all of the recorded lightning accidents. ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 16 of 25

of the lightning flash density in Sri Lanka, and the recorded number of total deaths and injuries in the percentage-wise distribution during all 12 months, whereas Figure 13 shows the spatial variation of the lightning flash density in Sri Lanka and the recorded number of damaged properties. The statistical details of the lightning flash density in Sri Lanka—extracted from the aforementioned raster maps using zonal statistics—are tabulated in Appendix A: Table A3, Table A4, Table A5, and Table A6. As stated in Table A3, the annual average lightning flash density of Sri Lanka is 8.26 flashes km-2 year-1 (maxi- ISPRS Int. J. Geo-Inf. 2021, 10, 117 mum = 28.05, minimum = 0.84, and standard deviation = 3.88). As stated in Table 15A4, of the 22 highest lightning flash density of Sri Lanka is in April (average = 31.33 flashes km-2 year-1, maximum = 146.76, minimum = 0.02, and standard deviation = 23.31), whereas January recordedFigure the 14 minimuma–d shows (average the district-wise = 2.00 flashes percentage km-2 year variation-1, maximum of the = total 22.78, lightning minimum ac- = cidents0.00, and reported standard in Srideviation Lanka from= 3.84). 1974 As tostated 2019. in It Table is a visual A5, with interpretation regards to ofthe the climate data summarizedseasons, the in highest Table3 .lightning The administrative flash density districts of Sri (ADs) Lanka in was the western reported and in southwesternthe first inter- regionsmonsoon in theseason country (average were = more22.25 proneflashes to km lightning-2 year-1, accidents maximum than = 85.88, the ADs minimum in the north= 0.79, andand northeastern standard deviation regions = during 15.09). theMoreover, considered as stated period. in Table A6, the Kegalle district rec- ordedThere the couldhighest be lightning many other flash reasons density which (average impact = 17.27 the aforementionedflashes km-2 year lightning-1, maximum acci- = dents27.19, in minimum addition = to 7.53, the and influence standard caused deviation by climate = 3.39), seasons whereas and the the Jaffna respective district regionalrecorded variationsthe lowest of (average the lightning = 1.87 flash flashes density, km-2 year together-1, maximum with the = geographical 3.01, minimum location. = 0.84, In and a recent stand- study,ard deviation it was reported = 0.45). that The there variations is an increasing of the average trend of lightning lightning flash activity densities in Sri Lanka, in terms with of 24months, lightning districts, flashes and more seasons every are year, shown with anin Figure increase 4, ofFigure flash 5, density; and Figure0.093 7, flashes respectively, km−2 pertogether year [ 6with]. all of the recorded lightning accidents.

FigureFigure 11. 11.Variation Variation of of the the lightning lightning flash flash density density with with the the recorded recorded lightning lightning accidents accidents (in (in %) %) in in Sri Sri Lanka, Lanka, from from 1974 1974 to to 2019,2019, for for all all four four climate climate seasons, season presenteds, presented district-wise: district-wise: (a) FIM(a) FIM deaths deaths and and injuries, injuries, (b) SWM (b) SWM deaths deaths and injuries, and injuries, (c) SIM (c) deaths and injuries, (d) NEM deaths and injuries, (e) FIM destroyed and damaged houses, (f) SWM destroyed and damaged houses, (g) SIM destroyed and damaged houses, and (h) NEM destroyed and damaged houses. It is a well-known fact that human activities in the open field are vulnerable to lightning accidents during a thunderstorm. On the other hand, paddy cultivation plays a dominant role in the crop cultivation of Sri Lanka. The two major paddy cultivation seasons are the Maha season and Yala Season. In general, the Yala season overlaps the first inter-monsoon and southwest monsoon rains. The Maha season commences with the beginning of the second inter-monsoon rains. According to this study, there is a high tendency of lightning accidents occurring in highly lightning-active periods, such as the first and second inter-monsoon seasons. Most of the administrative districts that were identified as the dominant lightning accident regions during the aforementioned two ISPRS Int. J. Geo-Inf. 2021, 10, 117 16 of 22

ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW inter-monsoon seasons are the well-known prominent districts that perform17 of the25 paddy cultivation of the country. Therefore, agricultural activities in rural areas may act as a dominant medium for lightning victims, which mostly could be due to either negligence of avoiding lightning accidents in the ﬁeld, or not following proper outdoor safety guidelines. SIM deaths and injuries, (d) NEM deaths andTherefore, injuries, ( farmerse) FIM destroyed who are engaging and damaged in paddy houses, cultivation (f) SWM in thedestroyed aforementioned and districts damaged houses, (g) SIM destroyed and damagedshould houses, completely and (h avoid) NEM ﬁeld destroyed activities and during damaged a thunderstorm. houses.

Figure 12.FigureVariation 12. Variation of the lightning of the ﬂash lightning density flas withh density the recorded with deathsthe recorded and injuries deaths (in and %) ininjuries Sri Lanka (in from%) in 1974 to 2019 forSri all 12Lanka months, from presented 1974 to 2019 district-wise: for all 12 ( amonths,) January, presented (b) February, district-wise: (c) March, (da) April,January, (e) May,(b) February, (f) June, (g(c)) July, (h) August,March, (i) September, (d) April, ( j()e October,) May, ( (fk) )June, November, (g) July, and (h (l)) August, December. (i) September, (j) October, (k) November, and (l) December.

ISPRS Int. J. Geo-Inf. 2020ISPRS, 9 Int., x FOR J. Geo-Inf. PEER2021 REVIEW, 10, 117 18 of 25 17 of 22

Figure 13.FigureVariation 13. of Variation the lightning of the ﬂash lightning density flas withh thedensity recorded with property the recorded damage property (in %) in damage Sri Lanka, (in from%) in 1974 Sri to 2019, for allLanka, 12 months, from presented1974 to 2019, district-wise: for all 12 (months,a) January, presented (b) February, district-wise: (c) March, ( (ad)) January, April, (e) ( May,b) February, (f) June, ((gc) July, (h) August,March, (i) September, (d) April, (j) October,(e) May, ( k(f)) November, June, (g) July, and ((lh) December.) August, (i) September, (j) October, (k) November, and (l) December. Moreover, the community should avoid outdoor activities during the thunderstorm Figure 14a–dseason shows as much the district-wise as possible, and percentage they should variation fix their of attention the total on lightning mitigating acci- lightning accidents. Continuous lightning awareness programs, together with possible mitigation dents reported in Sri Lanka from 1974 to 2019. It is a visual interpretation of the data sum- techniques and safety guidelines, should be held in all of the identified districts, and with the marized in Tablerelevant 3. The stakeholders. administrative Structural districts and human (ADs) protectionin the western techniques and andsouthwestern systems, lightning regions in the protectioncountry were in low more voltage prone power to lightning systems, insulation accidents coordination, than the ADs and in effective the north grounding and northeasternsystems regions should during be the the main considered objectives period. of the lightning safety awareness programs. As a There couldlong-term be many strategy, other itreasons is recommended which im thatpact these the aforementioned programs could be lightning incorporated acci- into the dents in additionschool to the curriculum. influence Moreover, caused by as anclimate effective seasons way ofand utilizing the respective the findings regional of this study variations of theas practicallightning measurements flash density, to together make inhabitants with the safe,geographical it is recommended location. In to incorporatea recent study, it thesewas reported findings forthat the there aforementioned is an increasing lightning trend safety of awarenesslightning programs,activity in and Sri to add Lanka, with 24 lightning flashes more every year, with an increase of flash density; 0.093 flashes km-2 per year [6].

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the same into the school curriculum in an appropriate manner. The Disaster Management Centre (DMC) and the Department of Meteorology of Sri Lanka can play an active role in this regard. On the other hand, a considerable number of awareness programs for students and lightning protection workshops for other stakeholders have been conducted in different regions in the country in the past [14]. Furthermore, it is highly recommended to increase public awareness about the importance of adopting the recently-updated lightning protection standards issued by the International Electrotechnical Commission (IEC) during the implementation of new construction projects to mitigate lightning hazards [19,20]. These standards are entwined with different disciplines, such as general principles of lightning activities, risk management, physical damages to structures and life hazards, and the protection of electronic systems from lightning. Moreover, the implemented thunderstorm warning systems based on IEC standards can be recognized as one of the crucial solutions to mitigate unexpected lightning accidents all over the country [21]. Moreover, the findings of this study may be useful for carrying out further investigations to distinguish physical damage (fire, explosion, mechanical damage, etc.) and the damage to electrical and electronic systems within a structure due to the lightning electromagnetic pulse (LEMP). In order to identify the lightning-active periods and areas which are more vulnerable to lightning accidents, studies should be extended to investigate additional effective precautions to ISPRS Int. J. Geo-Inf. 2020, 9, x FOR PEER REVIEW 19 of 25 mitigate lightning accidents. However, it is a must that the public should regularly practice ordinary safety guidelines to mitigate lightning hazards.

FigureFigure 14.14. DistributionDistribution ofof thethe lightninglightning accidentsaccidents inin thethe administrativeadministrative districtsdistricts ofof SriSri Lanka,Lanka, fromfrom1974 1974to to2019: 2019: ((aa)) deathsdeaths duedue toto lightninglightning strikes,strikes, ((bb)) injuriesinjuries duedue toto lightninglightning strikes,strikes, ((cc)) destroyeddestroyed houses houses due due toto lightninglightning strikes,strikes, andand ((dd)) damageddamaged houseshouses duedue toto lightninglightning strikes.strikes.

6. ConclusionsIt is a well-known fact that human activities in the open field are vulnerable to lightning accidents during a thunderstorm. On the other hand, paddy cultivation plays a dom- This paper reports a study carried out on the recorded number of lightning accidents inant role in the crop cultivation of Sri Lanka. The two major paddy cultivation seasons during the period from 1974 to 2019, which includes 549 deaths, 498 injured people, are the Maha season and Yala Season. In general, the Yala season overlaps the first inter- 39 destroyed houses, and 741 damaged houses. According to the geographical distribution monsoon and southwest monsoon rains. The Maha season commences with the beginning of the lightning accidents, during the period from 1974 to 2019, the maximum number of of the second inter-monsoon rains. According to this study, there is a high tendency of 47 deaths was recorded in the Ratnapura district (AD 17), and 43 deaths were recorded lightning accidents occurring in highly lightning-active periods, such as the first and sec- in the Kalutara district (AD 25), with 8.6% and 7.8%, respectively, from the overall point ond inter-monsoon seasons. Most of the administrative districts that were identified as of view, and just one death recorded in the Mannar district (AD 11), which was the the dominant lightning accident regions during the aforementioned two inter-monsoon minimum. Furthermore, the maximum number of 75 injuries due to lightning accidents seasons are the well-known prominent districts that perform the paddy cultivation of the was recorded in the Polonnaruwa district (AD 8), followed by 51 injuries in the Kegalle districtcountry. (AD Therefore, 16), with agricultural 15.1% and 10.2%,activities respectively. in rural areas The may maximum act as a number dominant of damages medium forfor houseslightning (280 victims, houses) which happened mostly incould the Kegallebe due to district either (ADnegligence 16), with of avoiding 37.8% during lightning the accidents in the field, or not following proper outdoor safety guidelines. Therefore, farm- ers who are engaging in paddy cultivation in the aforementioned districts should completely avoid field activities during a thunderstorm. Moreover, the community should avoid outdoor activities during the thunderstorm season as much as possible, and they should fix their attention on mitigating lightning accidents. Continuous lightning awareness programs, together with possible mitigation techniques and safety guidelines, should be held in all of the identified districts, and with the relevant stakeholders. Structural and human protection techniques and systems, lightning protection in low voltage power systems, insulation coordination, and effective grounding systems should be the main objectives of the lightning safety awareness programs. As a long-term strategy, it is recommended that these programs could be incorporated into the school curriculum. Moreover, as an effective way of utilizing the findings of this study as practical measurements to make inhabitants safe, it is recommended to incorporate these findings for the aforementioned lightning safety awareness programs, and to add the same into the school curriculum in an appropriate manner. The Disaster Management Centre (DMC) and the Department of Meteorology of Sri Lanka can play an active role in this regard. On the other hand, a considerable number of awareness programs for students and lightning protection workshops for other stakeholders have been conducted in different regions in the country in the past [14]. Furthermore, it is highly recommended to increase public awareness about the importance of adopting the re-

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considered period. According to the temporal variation of the lightning accidents, the maximum number of deaths (204 deaths) and injuries (196 injuries) was recorded in the first inter-monsoon season, and the minimum number of deaths (47 deaths) and injuries (46 injuries) was recorded in the northeast monsoon season during the period from 1974 to 2019. The maximum number of destroyed (17 houses) and damaged (283 houses) houses was recorded in the second inter-monsoon season. Furthermore, the maximum number of deaths (150 deaths) and injuries (147 injuries) due to lightning accidents was recorded in April. On the other hand, the maximum number of destroyed (10 houses) and damaged (151 houses) houses due to lightning activities was recorded in May. Moreover, as per the recorded data, the maximum number of 68 people died due to lightning accidents in 2012, and the maximum number of 67 people were injured in 2008. It was also observed that there is a relationship between the lightning flash density and the recorded number of lightning accidents over Sri Lanka, and higher lightning flash density in a particular area tends to lead to higher lightning hazards. Most of the areas that were identified as high-risk lightning accident regions are well known for agricultural activities, and those activities will eventually create the platform for lightning victims. Therefore, it is recommended that people should completely avoid field activities during a thunderstorm as much as possible, or they should regularly follow the lightning safety guidelines. Nevertheless, further studies are recommended in order to investigate additional effective precautions to mitigate lightning accidents. The results show that, on average, 11.93 people are killed and 10.83 people are injured in a year for the study period from 1974 to 2019. However, based on the reported accidents only for the period from 2000 to 2019, 18.40 people are killed and 16.50 people are injured per year. Furthermore, for the study period from 1974 to 2019, the average numbers of destroyed houses and damaged houses in a year were 0.85 and 16.11, respectively, whereas for the period from 2000 to 2019, these numbers increased to 1.90 and 35.30, respectively. For the study period considered from 1974 to 2019, according to the reported lighting accidents, there was a significant increase in the number of deaths, injuries, and property damage in the last two decades (2000–2019), and for said period, 67.03% of deaths, 66.27% of injuries, 97.44% of destroyed houses, and 95.28% of damaged houses were reported. According to the results of this study, it can be concluded that, for the period from 1974 to 2019 (46 years), in Sri Lanka, 0.56 people per million per year are killed, and 0.51 people per million per year are injured due to lightning. Nevertheless, as per the reported accidents from 2000 to 2019 (20 years), these estimated values are significantly higher: 0.86 people per million per year were killed, and 0.77 people per million per year were injured for this period.

Author Contributions: Conceptualization, M.E. and U.G.D.M.; Data curation, U.G.D.M.; Formal analysis, U.G.D.M.; Investigation, U.G.D.M.; Methodology, M.E. and U.G.D.M.; Resources, M.E.; Validation, M.E.; Visualization, M.E. and U.G.D.M.; Writing—original draft, U.G.D.M.; Writing— review and editing, M.E. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Informed Consent Statement: Not applicable. Data Availability Statement: Lightning accidents data are available at the DesInventar database maintained by the Disaster Management Centre (DMC), Colombo 07, Sri Lanka Sri Lanka (http://www. desinventar.lk:8081/DesInventar/main.jsp (accessed on 24 February 2021)). Lightning flash data are available at Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measurement Mission (TRMM) of NASA (https://lightning.nsstc.nasa.gov/data/data_lis.html (accessed on 24 February 2021)). Acknowledgments: The assistance provided by the Department of Physics, University of Colombo, is highly acknowledged. The authors are thankful to the Disaster Management Centre, Colombo 07, Sri Lanka, for providing the data in the DesInventar database. The assistance provided by Pradeep Kodippli and Mithma Gunasekera is also acknowledged. Conﬂicts of Interest: The authors declare no conﬂict of interest. ISPRS Int. J. Geo-Inf. 2021, 10, 117 20 of 22

Appendix A

Table A1. Statistical variations of the deaths and injuries in each administrative district of Sri Lanka due to lightning, from 1974 to 2019.

Number of Deaths Number of Injuries District District Standard Standard Number Average Maximum Minimum Average Maximum Minimum Deviation Deviation AD 1 Kandy 0.59 5 0 1.27 0.83 10 0 2.10 AD 2 Matale 0.15 3 0 0.60 0.17 6 0 0.93 AD 3 Nuwara Eliya 0.20 3 0 0.54 0.15 3 0 0.63 AD 4 Ampara 0.43 4 0 0.86 0.41 7 0 1.33 AD 5 Batticaloa 0.37 4 0 1.00 0.20 4 0 0.72 AD 6 Trincomalee 0.17 2 0 0.49 0.11 2 0 0.43 AD 7 Anuradhapura 0.67 6 0 1.37 0.41 6 0 1.29 AD 8 Polonnaruwa 0.87 5 0 1.51 1.63 62 0 9.15 AD 9 Jaffna 0.30 3 0 0.76 0.17 4 0 0.68 AD 10 Kilinochchi 0.17 2 0 0.49 0.28 11 0 1.64 AD 11 Mannar 0.02 1 0 0.15 0.07 2 0 0.33 AD 12 Mullaittivu 0.11 2 0 0.38 0.11 2 0 0.43 AD 13 Vavuniya 0.15 3 0 0.56 0.09 2 0 0.41 AD 14 Kurunegala 0.67 8 0 1.43 0.30 6 0 1.03 AD 15 Puttalam 0.57 5 0 1.11 0.39 5 0 1.02 AD 16 Kegalle 0.85 8 0 1.40 1.11 17 0 2.95 AD 17 Ratnapura 1.02 6 0 1.63 0.78 7 0 1.80 AD 18 Galle 0.59 4 0 1.05 0.78 17 0 2.76 AD 19 Hambantota 0.35 3 0 0.77 0.17 3 0 0.57 AD 20 Matara 0.37 7 0 1.16 0.41 12 0 1.89 AD 21 Badulla 0.54 6 0 1.17 0.57 13 0 2.07 AD 22 Moneragala 0.76 9 0 1.61 0.43 7 0 1.42 AD 23 Colombo 0.39 4 0 0.77 0.13 4 0 0.62 AD 24 Gampaha 0.67 4 0 1.03 0.43 10 0 1.63 AD 25 Kalutara 0.93 6 0 1.34 0.67 8 0 1.69

Table A2. Statistical variations of the property damage in each administrative district of Sri Lanka due to lightning, from 1974 to 2019.

Number of Deaths Number of Injuries District District Standard Standard Number Average Maximum Minimum Average Maximum Minimum Deviation Deviation AD 1 Kandy 0.00 0 0 0.00 1.00 15 0 3.14 AD 2 Matale 0.00 0 0 0.00 0.07 1 0 0.25 AD 3 Nuwara Eliya 0.15 4 0 0.67 0.22 9 0 1.33 AD 4 Ampara 0.00 0 0 0.00 0.13 1 0 0.34 AD 5 Batticaloa 0.04 1 0 0.21 0.30 6 0 1.17 AD 6 Trincomalee 0.00 0 0 0.00 0.13 6 0 0.88 AD 7 Anuradhapura 0.00 0 0 0.00 0.35 11 0 1.72 AD 8 Polonnaruwa 0.00 0 0 0.00 0.07 2 0 0.33 AD 9 Jaffna 0.00 0 0 0.00 0.11 2 0 0.43 AD 10 Kilinochchi 0.02 1 0 0.15 0.09 4 0 0.59 AD 11 Mannar 0.02 1 0 0.15 0.09 2 0 0.35 AD 12 Mullaittivu 0.00 0 0 0.00 0.09 4 0 0.59 AD 13 Vavuniya 0.00 0 0 0.00 0.22 2 0 0.59 AD 14 Kurunegala 0.15 5 0 0.76 0.91 23 0 3.49 AD 15 Puttalam 0.02 1 0 0.15 0.80 16 0 3.11 AD 16 Kegalle 0.09 1 0 0.28 6.09 110 0 20.98 AD 17 Ratnapura 0.02 1 0 0.15 0.78 11 0 2.33 AD 18 Galle 0.00 0 0 0.00 0.61 13 0 2.26 AD 19 Hambantota 0.04 1 0 0.21 0.59 14 0 2.21 AD 20 Matara 0.00 0 0 0.00 0.30 5 0 0.84 AD 21 Badulla 0.04 1 0 0.21 0.80 29 0 4.32 AD 22 Moneragala 0.00 0 0 0.00 0.48 11 0 1.92 AD 23 Colombo 0.09 3 0 0.46 0.15 3 0 0.56 AD 24 Gampaha 0.02 1 0 0.15 0.72 15 0 2.52 AD 25 Kalutara 0.13 2 0 0.40 1.02 21 0 3.80 ISPRS Int. J. Geo-Inf. 2021, 10, 117 21 of 22

Table A3. Statistics of the annual lightning ﬂash density, based on the 1998–2014 LIS Data from the TRMM Satellite.

Annual Lightning Flash Density (ﬂashes km−2 year−1) Average Maximum Minimum Standard Deviation 8.26 28.05 0.84 3.88

Table A4. Statistics of the monthly variations of the lightning ﬂash density, based on the 1998–2014 LIS Data from the TRMM Satellite.

(ﬂashes km−2 year−1) Month Average Maximum Minimum Standard Deviation January 2.00 22.78 0.00 3.84 February 4.61 65.88 0.00 7.62 March 14.35 85.67 0.00 12.23 April 31.33 146.76 0.02 23.31 May 9.93 58.20 0.00 6.76 June 3.74 57.27 0.00 5.29 July 2.08 25.16 0.00 2.60 August 6.66 59.61 0.00 7.37 September 6.55 49.55 0.00 5.78 October 12.87 59.77 0.00 8.60 November 6.09 45.64 0.00 6.47 December 2.20 20.44 0.00 2.75

Table A5. Statistics of the seasonal variations of the lightning ﬂash density, based on the 1998–2014 LIS Data from the TRMM Satellite.

(ﬂashes km−2 year−1) Climate Season Average Maximum Minimum Standard Deviation FIM 22.25 85.88 0.79 15.09 SWM 5.67 23.66 0.16 3.51 SIM 9.29 35.65 0.40 5.32 NEM 2.99 31.99 0.26 3.91

Table A6. Statistics of the variations of the lightning ﬂash density in each administrative district of Sri Lanka, based on the 1998–2014 LIS Data from the TRMM Satellite.

District (ﬂashes km−2 year−1) District Number Average Maximum Minimum Standard Deviation AD 1 Kandy 7.29 16.61 3.18 1.95 AD 2 Matale 8.38 10.47 6.45 0.74 AD 3 Nuwara Eliya 6.18 14.06 2.10 2.01 AD 4 Ampara 6.40 14.74 1.06 3.50 AD 5 Batticaloa 5.54 10.93 1.12 1.92 AD 6 Trincomalee 5.98 8.07 3.58 0.80 AD 7 Anuradhapura 8.00 11.73 5.12 1.08 AD 8 Polonnaruwa 8.81 13.93 5.48 1.06 AD 9 Jaffna 1.87 3.01 0.84 0.45 AD 10 Kilinochchi 3.46 6.54 1.87 1.03 AD 11 Mannar 5.93 9.83 1.51 1.78 AD 12 Mullaittivu 6.67 11.98 1.98 2.16 AD 13 Vavuniya 8.88 11.47 6.09 0.82 AD 14 Kurunegala 11.94 20.32 5.24 2.99 AD 15 Puttalam 5.73 10.95 2.51 1.42 AD 16 Kegalle 17.27 27.19 7.53 3.39 ISPRS Int. J. Geo-Inf. 2021, 10, 117 22 of 22

Table A6. Cont.

District (ﬂashes km−2 year−1) District Number Average Maximum Minimum Standard Deviation AD 17 Ratnapura 10.22 21.22 3.03 3.70 AD 18 Galle 10.82 16.58 4.73 1.83 AD 19 Hambantota 3.61 7.68 1.53 1.23 AD 20 Matara 5.27 11.28 1.77 1.80 AD 21 Badulla 8.45 14.84 3.36 1.63 AD 22 Moneragala 8.21 16.25 1.94 2.62 AD 23 Colombo 15.50 28.05 9.11 3.82 AD 24 Gampaha 16.74 27.94 5.72 3.21 AD 25 Kalutara 14.84 19.96 9.38 2.31

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