Open Access Digital Repository of Ministry of Earth Sciences, Government of India

Observed trends and changes in daily temperature and precipitation extremes over the Koshi river basin

Shrestha, AB and Bajracharya, SR and Sharma, AR and Duo, C and Kulkarni, A (2017) Observed trends and changes in daily temperature and precipitation extremes over the Koshi river basin. International Journal of Climatology, 37 (2). pp. 1066-1083.

[img] PDF
Observed trends and changes.pdf - Published Version

Download (62MB)


The Koshi river basin is a sub-basin of the Ganges shared among China, Nepal, and India. The river system has a high potential for investment in hydropower development and for irrigation in downstream areas. The upper part of the basin contains a substantial reserve of freshwater in the form of snow and glaciers. Climate variability, climate change, and climate extremes might impact on these reserves, and in turn impact on systems that support livelihoods, such as agriculture, biodiversity and related ecosystem services. Climatological variability and trends over the Koshi river basin were studied using RClimDex. Daily temperature data (20 stations) and precipitation data (50 stations) from 1975 to 2010 were used in the analysis. The results show that the frequency and intensity of weather extremes are increasing. The daily maximum temperature (TXx) increased by 0.1 °C decade−1 on average between 1975 and 2010 and the minimum (TNn) by 0.3 °C decade−1. The number of warm nights increased at all stations. Most of the extreme temperature indices showed a consistently different pattern in the mountains than in the Indo-Gangetic plains, although not all results were statistically significant. The warm days (TX90p), warm nights (TN90p), warm spell duration (WSDI), and diurnal temperature range (DTR) increased at most of the mountain stations; whereas monthly maximum and minimum values of daily maximum temperature, TX90p, cool nights (TN10p), WSDI, cold spell duration indicator (CSDI), DTR decreased at the stations in the Indo-Gangetic plains, while the number of cold days increased. There was an increase in total annual rainfall and rainfall intensity, although no clear long-term linear trend, whereas the number of consecutive dry days increased at almost all stations. The results indicate that the risk of extreme climate events over the basin is increasing, which will increase people's vulnerability and has strong policy implications.

Item Type: Article
Additional Information: Copyright of this article belongs to the Authors. International Journal of Climatologypublished by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
Uncontrolled Keywords: climate extremes; Koshi basin; temperature; precipitation; climate indices
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 21 Dec 2017 10:03
Last Modified: 21 Dec 2017 10:03

Actions (login required)

View Item View Item