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To access the closeness of DEMs topography with the real field elevation, we evaluated the vertical accuracy of eight different freely accessible DEMs across different physiographic regions and the river basins of Nepal. Results revealed that MERIT DEM (90 m resolution) with RMSE of 9 m was found to be superior to other DEMs in Nepal's low-lying Terai plains where the elevation range lies between 59 m-721 m. In High mountains (515 m-5202 m) and High Himalayas (2150 m-8749 m) with higher elevation, SRTM90m with RMSE 260 m and 323 m respectively, outperformed all its counterpart. Meanwhile, in Siwalik and the middle mountains, both SRTM90m and HYDROSHEDS exhibited almost similar RMSE of 106 m indicating their compatible uses in these regions. Meanwhile, the accuracy assessment across different river basins of Nepal discerned that the accuracy of SRTM90m was above others in larger river basins like Koshi (RMSE 224 m), Narayani (RMSE 215 m) and Karnali (RMSE 265 m) where the range of elevation is greater. In the smaller to medium-sized basins like Kankai, Kamala, Bagmati, West Rapti and Babai, HYDROSHEDS was found preferable along with SRTM90m. Based on different error statistics, the rankings are given to each DEM in order of their accuracy. [ABSTRACT FROM AUTHOR]

Streamflow alteration is one of the most noticeable effects of changes in rainfall patterns (both intensity and amount) in the Himalayan region. Additionally, the impact of climate change on the localized rainfall patterns is particularly significant, which is more crucial in the Himalayas. This study carries out a comprehensive analysis on temporal variability of the rainfall and its relation to streamflow in a typical mountain river basin, located in the southern aspect of central Himalayas. The primary objective of this study is to analyze seasonal and annual rainfall trends across rain gauge stations within the selected Kali Gandaki (KG) River Basin. Monthly rainfall data were used to examine the rainfall and streamflow trends. Mann-Kendall (MK) trend test, Sen's slope, and sequential MK (SQMK) analysis were employed to evaluate monotonic trends on homogenized time series data. Our findings revealed the formation of an anticlockwise hysteresis loop between streamflow and rainfall within the catchment. Understanding the relationship between streamflow and rainfall would provide a foundation for effective water resources management. [ABSTRACT FROM AUTHOR]

Notably, IMERG Early and Late products reveal a similar level of extreme precipitation detection, inferring the use of these products for a rapid assessment of extreme precipitation events. The extreme precipitation detection is "True" when both SPEs and rain gauge observations show a daily rainfall >=1mm, while it is "False" when SPEs detect rain during non-rainy days based on rain gauge observations. This paper illustrates the importance and applicability of satellite-based precipitation estimates to diagnose the hydrometeorological hazards in quasi-real-time and provides a baseline in early disaster preparedness for decision-makers in the Nepal Himalaya. [Extracted from the article]

Depleting fossil fuels and global commitments to reducing emissions have emphasized the necessity of exploring alternative resources to produce chemical fertilizer, specifically urea. This study presents a novel approach to producing eco-friendly urea in Nepal, utilizing municipal solid wastes in combination with hydroelectricity which provides solutions to three major problems namely waste management, surplus hydroelectricity utilization, and reduction of urea imports. The results obtained from the process simulation models developed in the Aspen Plus software reveal that approximately 661 metric tonnes per day of environmentally friendly urea can be produced by harnessing 740 and 220 metric tonnes per day of organic waste and combustible waste respectively, alongside the integration of an additional power supply of 230 MW. Sensitivity analysis on organic waste composition exhibits a constrained effect on the urea yield, whereas alterations in the carbon content of combustible waste exert a comparatively significant influence. The Monte Carlo financial risk assessment substantiates the profitable economic feasibility of the proposed production system, exhibiting a minimal investment risk. The cost of electricity emerges as the predominant factor in determining the levelized cost of urea and hence lowering the electricity prices specifically for urea production is recommended, whereas the waste cost exerts a relatively marginal influence. Additionally, the aggregate carbon dioxide emissions originating from the proposed plant amount to approximately 32.74 kg per metric tonne of urea, signifying a 29 times reduction in emissions when compared with fossil fuel-based urea production. • Cleaner way of producing urea utilizing municipal solid waste and hydroelectricity. • Process simulation models for all stages of production are developed in Aspen Plus. • 661 TPD urea produced utilizing 962 TPD waste and 230 MW of electricity. • The proposed system is financially attractive with minimal investment risk. • Electricity price highly influences the cost of urea production. [ABSTRACT FROM AUTHOR]