Abstract
Several natural disasters such as lightning, flood, fire, epidemics, and landslides frequently occur in the Himalayan region, of Nepal. The altitude of this region ranges from 59 m to “8848.86 m”—the height of Mount Everest—along with a distance of just 160 km. As a result, there is a considerable (i.e., nearly 95°C) variation in temperature in the region. Moreover, Nepal has a heterogeneous topography. All these features influence various natural disasters including lightning activity. This paper is aimed at analyzing the variations of lightning within and across the years from January 2011 to December 2021—a total of 11 years. For this, the data were taken from the Disaster Risk Reduction (DRR) portal of the Ministry of Home Affairs (MOHA). The analysis showed that there were no lightning events in November, and the lightning density was higher in the premonsoon period of study in this region. It also showed that the number of injured people is about thrice the death of the people due to the lightning. The null occurrence of lightning in November in the Himalayan region is a contribution novel to this field.
1. Introduction
The country of the Mount Everest, Nepal, lies in the northern hemisphere of latitude 26.37°N to 30.45°N and longitude 80.066°E to 88.2°E in a Himalayan region. The altitude of the country ranges heterogeneously from 59 m to 8848.86 m. The land of the lowest altitude lies in the Terai while that of the highest altitude (i.e., Mount Everest) lies in the Himalayan region. The air distance between them is about 160 km, and the temperature difference is about 95°C. Due to the variation of temperature in a short range of distance, there is the diversity in climate and the variation of weather phenomena [1, 2]. Water naturally flows from high altitude to low altitude with high speed due to the vast difference in altitude within the short range of distance. This causes frequent disasters such as floods and landslides resulting in the loss of human lives and cattle with the destruction of physical properties of billions of dollars [3].
In the case of lightning, various scholars, such as Malan [4], Rakov and Uman [5], and Mac Gorman and Rust [6], have explained that huge energy is released even if it is a more common natural activity in the atmosphere. The primary source of lightning is the cumulonimbus which produces thunderstorms, and it produces the energy and the power in the order of more than a hundred megawatts. They also reported that more than 24000 people were globally affected by lightning. The number of injured people due to this phenomenon of lightning was more than the casualties. Even Rakov and Uman [5] mentioned that thunderstorms produce within a minute more than 100 lightning flashes globally. Besides human casualties, the death of animals and sophisticated parts of electronic, military, and medical equipment can be destroyed by radiation produced due to lightning. Similarly, the communication and transmission lines get affected by electromagnetic radiation due to direct or indirect strikes of lightning. Gomes et al. [7] explained that besides the direct and indirect strike of the lightning, there may be death or injury to the people depending on the various factors. These factors may be the distance, step potential, current magnitudes, and so on. They also reported that the lightning causes harm to the human beings and domestic animals when they are in open agricultural fields and take shelter under tall trees to avoid the rain. Barros and Lang [8] reported that the effect of lightning in the Himalayan region is not well documented due to various factors even though the lightning signatures of the region are of very much interest to the scientific community of the world. Gomes [9] reported that lightning is taken as a disaster because of the geological scenario in the context of Sri Lanka in the mountainous region, and casualties of people are not reported accurately due to the scattered information on the Himalayan region.
Berger [10] has classified lightning into cloud-to-cloud and cloud-to-ground discharges. The author has further categorized the latter into positive and negative lightning. Moreover, Krehbiel [11] has added the types of lightning: if the positive charge transfers from the cloud to the ground, that is called positive lightning; and if the negative charge of the cloud transfers to the ground, that is called negative lightning. In the thunderstorm, the tripole charge structure in which positive and negative charges are equal in number lies at the upper and central part of the cloud, respectively; some pocket positive charge remains at the bottom part of the thunderstorm [12, 13]. Uman [14] explained that positive lightning discharge is stronger than the negative lightning discharge, and Rakov and Uman [5] added the same argument showing that the phenomena occur due to charge transfer so that high current flow in the positive lightning results in the temperature up to 30,000 K. Baral and Mackerras [15], Adhikari et al. [16], and Adhikari [17] reported that more positive lightning occurs in the hill and mountainous region.
2. Methodology
There are different methods of measuring the phenomenon of lightning such as photography, electric field measurement, magnetic field measurement, and acoustic measurements. The radiations of various wavelengths and DC to gigahertz frequencies were produced due to the phenomenon of lightning discharge. However, for the current research paper, the data were taken from a secondary source, namely, the Disaster Risk Reduction (DRR) portal of the Ministry of Home Affairs (MOHA). The lightning activities from January 2011 to December 2021 were analyzed in terms of their inter- and intra-annual variations and their distribution over Nepal’s hill and mountainous region.
3. Observation and Discussion
Nepal is one of the underdeveloped countries with the highest risk of disaster due to its geographical structure. The northern upper part of Nepal includes the rugged mountainous region covered by the high Himalayas, the lower southern part consists of plain Terai, and in between the two lies the hilly region. Disasters such as floods, landslides, thunderbolts, thunderstorms, and fires occur frequently in such a geographical structure [3, 18]. Fire in the dry season and flood in the rainy season are the disasters in the Terai belt of Nepal. The Terai region also consists of thick forests, and therefore, people suffer from the terror of wild animals. Landslides, floods, and epidemics in the rainy season are the main disasters in the hilly region while glacier lake outburst and avalanches are the potential disasters in the Himalayan region. However, thunderstorms and lightning phenomena occur all over the country irrespective of the particular region. In the Himalayan region, more than 250 animals were killed due to a single flash of lightning [19]. The phenomena of lightning in this geographical structure are very important. As mentioned earlier, the current, as well as temperature in the process of lightning, is very high, and within a very short time, it affects considerably. Here, the scenario of only the death of the human beings due to the natural disaster in Nepal during the studied period is shown in Table 1.
The death of people due to different disasters in Himalayan regions during the period is shown in Figure 1.
From January 2011 to December 2021, one thousand and fifty people were killed due to the lightning thunderbolt in Nepal but the number of injured people was about three times, that is, 2850. Even the loss of human beings was not exactly reported due to several reasons, then animals and the loss of properties were also not exactly collected. But the National Emergency Operation Center, Ministry of Home Affairs (NEOC, MOHA), reported the data in which the injured people and loss of property are presented here in Table 2. Among the disaster, lightning is one of them in Nepal and found that about 100 people on average lost their lives per annum and the injured number of people is about three times the death of the people. The number of the casualty of human beings, the number of lightning events, and several humans injured during this period are presented here. The bar diagram of the distribution of the lightning is expressed in Figure 2.
From 2011 to 2021, the number of incidents of the lightning phenomena and the number of injured and dead people were observed and analyzed the monthly distribution of the lightning within the period. As already mentioned, the data reported here is only the human loss and injured in the incidents of lightning. There is no mention of the death and injured number of animals or other exactly. There was a huge number of animals killed due to a single stroke in the high mountainous region [19]. In the mentioned period, one thousand and fifty people were killed due to the lightning thunderbolt in Nepal, and two thousand eight hundred and fifty were injured. In this period, the number of lightning incidents is two thousand four hundred and two. About 2400 people were killed annually in the world, but about more than 100 people on average were killed in Nepal only, as shown in Table 2 from the DRR portal. From 2012 to continue five years, 118, 147, 97, 103, and 118, respectively, were the number of people killed by it, indicating that lightning is the main disaster in Nepal. Since 2017, the casualty is going on decreasing order but the number of injured people is highly increased. It may be due to some awareness programs conducted in some local areas and the people know about how to survive the direct strike of the lightning. Not only the casualty of the people but there were also more incidents and the injured number was about three times of the casualty. The number of incidents and a number of dead and injured people due to lightning in twelve months with seasonal variations were observed and analyzed here which is shown in Table 3. The bar diagram of the monthly distribution of lightning during the period 2011 to 2021 is expressed in Figure 3.
The number of incidents, number of dead and injured people due to lightning events since 2011, and monthly distribution with seasonal variation of lightning were observed and analyzed here. From this data, there are no lightning events in November during this period of eleven years and the maximum lightning occurs during the premonsoon period. From this table, the maximum number of lightning incidents occurred in April, May, and June, in the premonsoon period, and the casualties, as well as the death of the people, were also high in the same period. The number of injured people in April in the premonsoon period is the maximum that can be seen in Figure 3. The number of injured people is about three times higher than the number of dead people on average, but in the premonsoon period, it is also very high. To observe the distribution of the lightning phenomena and severe thunderstorm over different regions, all over the country, the seventy-seven districts of Nepal are considered as a sample area. Again, the lightning phenomena were observed and analyzed in the data available on the DRR portal for seventy-seven districts. The observed data are presented here in Table 4, and the distribution of the lightning phenomena and severe thunderstorms over the seventy-seven districts of Nepal is represented by a bar diagram in Figure 4.
In our scenario, 48% of the population settled in the Terai region of altitudes 59 m to 600 m with only seventeen percent of the land area from east to west. On analyzing the above-observed data, in the high Himalayan region of an altitude of more than 5000 m, the fatalities are very rare due to both the reason of low population and low lightning flash density. The fatality rate is very low because it may be difficult to record and not approach the events. The main affected area due to lightning thunderstorms is in the central part of hilly mountains regions, which covers more than 68% of the total area, having altitude ranges from 600 m to 5000 m. This area of the mountainous region of very small breadth and is elongated from east to west as shown in Figure 5 using the software of ArcGIS mapping. Nepal is also shown in the inset of the map of Asia. The fatalities and injuries due to lightning thunderstorms over this area have both significantly higher populations and higher lightning flash density.
To observe the lightning distribution and severe thunderstorms over different districts of Nepal in different regions, it should be analyzed and have to determine the place at which the effect of lightning is more vulnerable all over the country. To determine the district-wise effect of thunderstorms all over the country, the incident of lightning events and the resultant human death and injuries were observed and analyzed. The number of human deaths and injuries due to lightning is represented in pie diagrams inside the map of Nepal by using the software of Arc map where the size of the pie diagram varies representing the variation in the number of lightning events as shown in Figure 6. The incident of lightning and the death of the people due to the lightning thunderstorm in the seventy-seven districts are presented here with the different colors in Figure 7 by using the software of Arc map.
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From analyzing the observation data of seventy-seven districts, the lightning thunderstorm occurred maximum in Makawanpur district in which the number of lightning events is up to 157 incidents in this studied period, and in Jhapa district occurred 84 incidents with the second-highest rank. Similarly, the higher lightning events to the lower lightning events that occurred among the 77 districts were ranked that is also expressed in Table 4. Among the seventy-seven districts, two districts, Manang and Mustang, have no lightning phenomena during this studied period. Lightning injuries and deaths may not be accurately reported because lightning most often strikes not the large groups but only the individuals, and the information, therefore, is scattered and mostly uncounted. As already mentioned, the same scenario mostly can be seen in the mountainous Himalayan region like Nepal. Similarly, the three districts Dolpa, Rasuwa, and Humla have no casualties during this period even though there are some lightning events in a rank as shown in Table 4.
4. Result and Discussion
Lightning is one of the major disasters based on the casualty of the people, loss of domestic animals, causing fires in the huge jungle, and many more. Due to lightning hazards, there are so many direct and indirect effects, unknowingly damaging television, computer, radio, phone, refrigerator, electronic gazettes, various equipment, and medical equipment, causing a fire in building due to high voltage, etc. So it is very dangerous and people should take precautions about it. During the lightning, there is a huge amount of current and high temperature in a transient so it can damage and cause loss of huge property, domestic animals, and human beings; hence, it is taken as a disaster. The distribution of the lightning phenomena and severe thunderstorms over the seventy-seven districts of Nepal was observed and analyzed from the data available on the DRR portal. The number of incidents and number of dead and injured people due to lightning events are expressed with the interannual variations, represented in Figure 2. The distribution of the lightning phenomena and severe thunderstorms during the period of January 2011 to December 2021 observed that the number of injured people is about three times higher than the number of dead people on average, and this value is higher in the premonsoon period. More than 100 people lost their lives annually before 2016 and after then slightly decreased the number of casualties. But the number of events of lightning even increased after 2016 as well, but the death of people decreased and the number of injured people increased. Here, the number of injured people is generally linearly proportional to several incidents, but after conducting some awareness programs on the hazard area, then maybe the number of casualties decreased. It means the awareness program may be very useful, and it should be conducted not only for the layman but also for the electronic and electrical engineers, medical persons, technicians, etc.
The monthly distribution of the lightning phenomena was also analyzed during this period over the mountainous country, Nepal. The number of incidents, number of death, and number of injured people due to lightning events were expressed monthly with seasonal variation and analyzed as shown in Figure 3. During this period of eleven years, the weather phenomena are calm after the rainy season and there is no charge formation during this period; hence, there are no lightning events in November. During the premonsoon period, there are more sunny days which warm the air as well as the atmosphere. The more water drops evaporate from the earth’s surface and charge developed in the thunderstorm during this activity; hence, the maximum lightning occurs during the premonsoon period. About three months before the monsoon is the premonsoon period in which the maximum number of lightning occurred. The lightning events occurred maximum in April, May, and June, and the casualties were also in the same period. The lightning discharge phenomenon that occurred between the cloud and ground is called CG lightning. The charge of the cloud can transfer to the ground during this period, and hence, more observations of the lightning occurred.
5. Conclusion
Lightning is the main disaster in mountainous regions. In our scenario, the altitude of the country ranges heterogeneously from 59 m to 8848.86 m. The land of the lowest altitude lies in the Terai while that of the highest altitude lies in the Himalayan region. The air distance between them is about 160 km, and the temperature difference is about 95°C. Due to the variation of temperature in a short range of distance, there is the diversity in climate and the variation of weather phenomena. The heterogeneous rugged topographical features of Nepal influence the environment and frequently occur lightning. The number of incidents, number of dead and injured people due to lightning events since 2011, and monthly as well as annual distribution of lightning were observed and analyzed. There are no lightning events in November during this period of eleven years, and the maximum lightning occurs during the premonsoon period. The maximum number of lightning occurred in April, May, and June, and the casualties were also high. The number of injured people is found about three times higher than the number of dead people. The distribution of the lightning phenomena and severe thunderstorms over different regions of seventy-seven districts of Nepal is also observed and analyzed based on the data available on the DRR portal.
Data Availability
The author can provide the data and materials at any time for the journal or editors if required.
Ethical Approval
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Consent
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Conflicts of Interest
There is no conflict of interest.
Authors’ Contributions
All the material preparation, data collection and analysis, and preparation of the full manuscript were performed by a single author.
Supplementary Materials
The author provided the data of all seventy-seven districts, in rank, maximum lightning of 25 districts and minimum lightning of 21 districts, and maximum lightning in Makawanpur and Jhapa during this period, and their representation in the graph is submitted in the supplementary file. (Supplementary Materials)