Drought characteristics over Nepal Himalaya and their relationship with climatic indices

Abstract

Understanding drought characteristics is vital for sustainable societal and ecosystem functioning, especially in ongoing climate change. The study investigates the drought characteristics over the Nepal Himalaya using the standardized precipitation index (SPI) based on monthly precipitation data from 220 ground stations between 1980 and 2016 at seasonal and annual timescales. The results show that occurrences of drought are more frequent after the 2000s, intensifying their severity and duration. The cumulative probabilities of short-term (SPI3) and long-term (SPI12) drought during the period 1980-2016 were 17.1% and 23.5%, respectively. The short-term drought over Nepal occurred with an average duration of 2.8 months and a severity of −4.3, whereas for long-term drought the duration and severity were 8.6 months and −13.9, respectively. Meanwhile, the seasonal drought shows that the spring and autumn drought events were slightly higher than summer and winter drought. The wavelet power spectrum shows the variability signals of winter, spring and summer drought were 2-8 and 8-16 years; however, the autumn drought index only varied at 2-8 years. The NINO3.4 is the primary controlling mode of variability for summer and annual drought, whereas the dipole moment index (DMI) is used for the autumn drought at an interannual timescale. The decadal variability of summer and annual drought is linked with the Pacific Decadal Oscillation, whereas winter and spring drought are linked to the Arctic Oscillation. Furthermore, the study contributes to the understanding of the drought characteristics and its controlling factors of variability over Nepal.

Interannual variability of spring fire in southern Nepal

“…Similarly, the area average interannual time series of the burned areas and in situ precipitation shows a significant negative correlation ( R = −0.75, p < 0.01; Figure 4a). During the fire season, the long dry spells can further exacerbate the fire burned areas; for example, the fire count and burned areas were higher than normal in the precipitation deficit year, that is, 2012, 2016, and 2019 (Hamal et al, 2020; Sharma et al, 2021). Moreover, a strong positive correlation of fire burned areas with the ERA5, and in situ surface air temperature (Figures 3b and 4b) indicates that high temperature can result in the dry condition that can initiate fire activities (Fang et al, 2021; Kim et al, 2020; Tang et al, 2021).…”

Drought variability, changes and hot spots across the African continent during the historical period (1928–2017)

“…This index has been used for different applications including climate research for different regions and seasons. Such studies include over Europe (e.g., Cammalleri et al, 2022; Lloyd‐Hughes & Saunders, 2002; Spinoni et al, 2014), Asia (e.g., Aadhar & Mishra, 2017; Sharma et al, 2021; Zhai et al, 2010), Northern America (e.g., Agnew, 2000; Sung & Stagge, 2022), South America (e.g., Sgroi et al, 2021; Zanvettor & Ravelo, 2000), Australia (e.g., Mpelasoka et al, 2008; Yildirim & Rahman, 2022) and Africa (e.g., Gader et al, 2022; Naumann et al, 2012; Ntale & Gan, 2003).…”

How resilient are waterways of the Asian Himalayas? Finding adaptive measures for future sustainability

“…Water resources are being depleted with increased water pollution in lakes, rivers, and groundwater aquifers (Pandit et al, 2014). The disparity in the volume of water released from the Himalayas between the monsoon and the dry season has led to extremes of high rainfalls, floods, and losses of infrastructure and lives, and also large‐scale crop failure and water scarcity due to prolonged droughts (Chinnasamy et al, 2015; Hamal et al, 2020; S. Sharma, Hamal, et al, 2021). Projections of future runoff tend to carry large uncertainty, which undermines system resilience and can have significant implications for water supply to downstream communities (Quincey et al, 2018).…”