Assessing the characteristics of extreme floods in Nepal
<p>This study examines the characteristics (magnitudes, trends, and frequency of occurrences) of extreme floods in Nepal, a country that is at significant risk from floods. Daily discharge data from 1980 to 2015 of three gauging stations (Chisapani of Karnali Basin, Devghat of Narayani Basin,...
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Copernicus Publications
2024-11-01
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| Series: | Proceedings of the International Association of Hydrological Sciences |
| Online Access: | https://piahs.copernicus.org/articles/387/3/2024/piahs-387-3-2024.pdf |
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| author | A. Bhattarai U. Bhattarai U. Bhattarai K. R. Maharjan L. P. Devkota L. P. Devkota |
| author_facet | A. Bhattarai U. Bhattarai U. Bhattarai K. R. Maharjan L. P. Devkota L. P. Devkota |
| author_sort | A. Bhattarai |
| collection | DOAJ |
| description | <p>This study examines the characteristics (magnitudes, trends, and frequency of occurrences) of extreme floods in Nepal, a country that is at significant risk from floods. Daily discharge data from 1980 to 2015 of three gauging stations (Chisapani of Karnali Basin, Devghat of Narayani Basin, and Chatara of Koshi Basin) were used to assess the largest 1 % of flows, the annual top five high flows, and floods of different return periods (2-, 5-, 10-, 20-, and 100-year). In addition, temporal trend analysis of the flood peaks was carried out using the Mann–Kendall test and Sen's slope estimates. Results show that the magnitudes of the largest 1 % flows range from 6310 to 17 900, from 6967 to 12 100, and from 6080 to 9610 m<span class="inline-formula"><sup>3</sup></span> s<span class="inline-formula"><sup>−1</sup></span> at Chisapani, Devghat, and Chatara, respectively. The monsoon, especially from mid-June to early September, consistently witnesses over 90 % of 1 % extreme flows, with August registering more than 51 % of these occurrences. July and August combine for 81 % of the top five flow events, predominantly in August. Despite insignificant flow changes at a 95 % confidence level, extreme floods (2-, 5-, 10-, 20-, and 100-year return periods) are concentrated heavily in July and August, with August's second fortnight recording the most flood events. This assessment emphasizes July and August as critical months for extreme floods, aiding Nepalese authorities in planning dynamic resource allocation, disaster response, and effective flood management.</p> |
| format | Article |
| id | doaj-art-0d6a2fbb408543d08b73ab8fdb5bc08c |
| institution | Kabale University |
| issn | 2199-8981 2199-899X |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Proceedings of the International Association of Hydrological Sciences |
| spelling | doaj-art-0d6a2fbb408543d08b73ab8fdb5bc08c2024-11-18T10:19:22ZengCopernicus PublicationsProceedings of the International Association of Hydrological Sciences2199-89812199-899X2024-11-013873810.5194/piahs-387-3-2024Assessing the characteristics of extreme floods in NepalA. Bhattarai0U. Bhattarai1U. Bhattarai2K. R. Maharjan3L. P. Devkota4L. P. Devkota5Water Modeling Solutions Pvt. Ltd. (WMS), Kathmandu, 44600, NepalWater Modeling Solutions Pvt. Ltd. (WMS), Kathmandu, 44600, NepalInstitute for Life Sciences and the Environment, University of Southern Queensland, Toowoomba, Queensland 4350, AustraliaWater Modeling Solutions Pvt. Ltd. (WMS), Kathmandu, 44600, NepalWater Modeling Solutions Pvt. Ltd. (WMS), Kathmandu, 44600, NepalNepal Academy of Science and Technology (NAST), Kathmandu, 44600, Nepal<p>This study examines the characteristics (magnitudes, trends, and frequency of occurrences) of extreme floods in Nepal, a country that is at significant risk from floods. Daily discharge data from 1980 to 2015 of three gauging stations (Chisapani of Karnali Basin, Devghat of Narayani Basin, and Chatara of Koshi Basin) were used to assess the largest 1 % of flows, the annual top five high flows, and floods of different return periods (2-, 5-, 10-, 20-, and 100-year). In addition, temporal trend analysis of the flood peaks was carried out using the Mann–Kendall test and Sen's slope estimates. Results show that the magnitudes of the largest 1 % flows range from 6310 to 17 900, from 6967 to 12 100, and from 6080 to 9610 m<span class="inline-formula"><sup>3</sup></span> s<span class="inline-formula"><sup>−1</sup></span> at Chisapani, Devghat, and Chatara, respectively. The monsoon, especially from mid-June to early September, consistently witnesses over 90 % of 1 % extreme flows, with August registering more than 51 % of these occurrences. July and August combine for 81 % of the top five flow events, predominantly in August. Despite insignificant flow changes at a 95 % confidence level, extreme floods (2-, 5-, 10-, 20-, and 100-year return periods) are concentrated heavily in July and August, with August's second fortnight recording the most flood events. This assessment emphasizes July and August as critical months for extreme floods, aiding Nepalese authorities in planning dynamic resource allocation, disaster response, and effective flood management.</p>https://piahs.copernicus.org/articles/387/3/2024/piahs-387-3-2024.pdf |
| spellingShingle | A. Bhattarai U. Bhattarai U. Bhattarai K. R. Maharjan L. P. Devkota L. P. Devkota Assessing the characteristics of extreme floods in Nepal Proceedings of the International Association of Hydrological Sciences |
| title | Assessing the characteristics of extreme floods in Nepal |
| title_full | Assessing the characteristics of extreme floods in Nepal |
| title_fullStr | Assessing the characteristics of extreme floods in Nepal |
| title_full_unstemmed | Assessing the characteristics of extreme floods in Nepal |
| title_short | Assessing the characteristics of extreme floods in Nepal |
| title_sort | assessing the characteristics of extreme floods in nepal |
| url | https://piahs.copernicus.org/articles/387/3/2024/piahs-387-3-2024.pdf |
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