Soil erosion is a major issue, causing the loss of topsoil and fertility in agricultural land in mountainous terrain. Estimation of soil erosion in Nepal is essential because of its ...agriculture-dependent economy (contributing 36% to national GDP) and for preparing erosion control plans. The present study, for the first time, attempts to estimate the soil loss of Nepal through the application of the Revised Universal Soil Loss Equation (RUSLE) model. In addition, it analyzes the effect of Land Use and Land Cover (LULC) and slope ( β ) exposition on soil erosion. Nation-wide mean annual soil loss of Nepal is estimated at 25 t ha−1 yr−1 with a total of 369 million tonnes (mT) of potential soil loss. Soil erosion based on the physiographic region of the country shows that the Middle Mountains, High Mountains, High Himal, Chure, and Terai have mean erosion rates of 38.0, 32.0, 28.0, 7.0, and 0.1 t ha−1 yr−1. The soil erosion rate by basins showed that the annual erosions of the Karnali, Gandaki, Koshi, and Mahakali River basins are 135, 96, 79, and 15 mT, respectively. The mean soil erosion rate was significantly high (34 t ha−1 yr−1) for steep slopes (β > 26.8%) and the low (3 t ha−1 yr−1) for gentle slopes (β < 5%). Based on LULC, the mean erosion rate for barren land was the highest (40 t ha−1 yr−1), followed by agricultural land (29 t ha−1 yr−1), shrubland (25 t ha−1 yr−1), grassland (23 t ha−1 yr−1), and forests (22 t ha−1 yr−1). The entire area had been categorized into 6 erosion classes based on the erosion severity, and 11% of the area was found to be under a very severe erosion risk (> 80 t ha−1 yr−1) that urgently required reducing the risk of erosion.
Himalayan glaciers, in general, are shrinking and glacial lakes are evolving and growing rapidly in number and size as a result of climate change. This study presents the latest remote sensing-based ...inventory (2017) of glacial lakes (size ≥0.0036 km2) across the Nepal Himalaya using optical satellite data. Furthermore, this study traces the decadal glacial lake dynamics from 1977 to 2017 in the Nepal Himalaya. The decadal mapping of glacial lakes (both glacial-fed and nonglacial-fed) across the Nepal Himalaya reveals an increase in the number and area of lakes from 1977 to 2017, with 606 (55.53 ± 16.52 km2), 1137 (64.56 ± 11.64 km2), 1228 (68.87 ± 12.18 km2), 1489 (74.2 ± 14.22 km2), and 1541 (80.95 ± 15.25 km2) glacial lakes being mapped in 1977, 1987, 1997, 2007, and 2017, respectively. Glacial lakes show heterogeneous rates of expansion in different river basins and elevation zones of Nepal, with apparent decadal emergences and disappearances. Overall, the glacial lakes exhibited ~25% expansion of surface areas from 1987 to 2017. For the period from 1987 to 2017, proglacial lakes with ice contact, among others, exhibited the highest incremental changes in terms of number (181%) and surface area (82%). The continuous amplified mass loss of glaciers, as reported in Central Himalaya, is expected to accompany glacial lake expansion in the future, increasing the risk of glacial lake outburst floods (GLOFs). We emphasize that the rapidly increasing glacial lakes in the Nepal Himalaya can pose potential GLOF threats to downstream population and infrastructure.
What are the main morphological factors that control the heterogeneous responses of debris-covered glaciers to climate change in the southern central Himalaya? A debate is open whether thinning rates ...on debris-covered glaciers are comparable to those of debris-free ones. Previous studies have adopted a deterministic approach, which is indispensable, but is also limiting in that only a few glaciers can be monitored. In this context, we propose a statistical analysis based on a wider glacier population as a complement to these deterministic studies. We analysed 28 glaciers situated on the southern slopes of Mt. Everest in the central southern Himalaya during the period 1992–2008. This study combined data compiled by three distinct studies for a common period and population of glaciers for use in a robust statistical analysis. Generally, surface gradient was the main morphological factor controlling the features and responses of the glaciers to climate change. In particular, the key points that emerged are as follows. 1) Reduced downstream surface gradient is responsible for increased glacier thinning. 2) The development of supraglacial ponds is a further controlling factor of glacier thinning: where supraglacial ponds develop, the glaciers register further surface lowering. 3) Debris coverage and thickness index were not found to be significantly responsible for the development of supraglacial ponds, changes in elevation, or shifts in snow line altitude.
•Downstream surface gradient is the main factor controlling changes in mass balance, surface, SLA, pond density.•Reduced downstream surface gradient is responsible for increased glacier thinning.•Where supraglacial ponds develop the glaciers register further glacier thinning.•Debris coverage and thickness were not found significantly responsible for changes in glacier elevation.
Springs are primary water sources for drinking and sanitation in rural households of mountainous areas and are ecologically important as they provide habitat to diverse macroinvertebrate assemblages. ...This study assesses the spring sources to clarify concerns about the quality and safety of this water used for human use, as well as the condition of the biological habitat in the Jhimruk River Watershed (JRW), Nepal. Spring sources were mapped and samples of water and benthic macroinvertebrates were analyzed during the pre- and post-monsoon seasons. One hundred and two springs were documented with their characteristics. Field assessment shows that the discharges of more than 90% of the springs have decreased in the last 10 years which has increased the water stress for drinking water sources and for sanitation for communities in the region. Except for pH, EC, and total hardness, all other measured physicochemical parameters were below the WHO and National Drinking Water Quality Standards of Nepal, currently indicating no threat to consumer’s health. Water quality index scores indicate the water from the springs is excellent in the post-monsoon and excellent to good in the pre-monsoon seasons. Low seasonal chemical variability observed with a higher spatial difference, driven by the geology. We documented 38 macroinvertebrates families in the post-monsoon and 32 families in the pre-monsoon season. Macroinvertebrate richness total and Ephemeroptera-Plecoptera-Trichoptera (EPT) was greater in flowing springs compared to stagnant springs which were numerically dominated by Chironomidae. Discharge rate, elevation, EC, and nitrate concentrations were the main influencing factors shaping macroinvertebrate assemblages in the springs. We emphasize that actions must be implemented to conserve the societal and ecological value of Himalayan springs.
Enflamed CO2 emissions from cement production in Nepal Thakuri, Sudeep; Khatri, Singh Bahadur; Thapa, Sabita
Environmental science and pollution research international,
12/2021, Letnik:
28, Številka:
48
Journal Article
Recenzirano
Cement industry is one of the main contributors to greenhouse gas (GHG) emissions, specifically carbon dioxide (CO
2
). This paper presents the cement production and the CO
2
emissions from the ...cement industry in Nepal. We compute emissions for the process-related, combustion-related (fuel use), and electricity-related activities during the cement production. We used eight emission factors (EFs) for the process-related, two EFs for the combustion or fuel-related, and two for the electricity-related activities using the previous researches. We computed the emissions as a product of the activities and the EFs. The estimated CO
2
emission in 2019 from the cement production is 3.45 ± 0.50 million metric tons (mMt) for Nepal. In 2019, the emissions are 1.87 ± 0.16 mMt from the process-related, 1.52 ± 0.34 mMt from the combustion-related, and 0.062 ± 0.004 mMt from the electricity use activities during the cement production in Nepal. Cumulative CO
2
emission was 22.73 ± 3.82 mMt from 1987 to 2019. Per capita CO
2
emission is 0.12 mMt for Nepal in 2019. Nepal contributes about 0.06% CO
2
emission from cement production to the global CO
2
emission (2.08 Gt) from the cement industry. By evaluating per capita gross domestic product (GDP) (from 1987/1988 to 2019/2020) and the human development index (HDI) (from 1990 to 2019) with the cement production, the result shows that cement production increases significantly (
p
< 0.01) with an increase in the GDP and the HDI. We emphasize that the study’s outputs are directly relevant to the country’s emission inventory, mitigation planning, and developing a strategy for cleaner production.
This study explores the link between area increase of Imja Tsho (Lake) and changes of Imja Glacier (area ~25km2) under the influence of climate change using multitemporal satellite imagery and local ...climate data. Between 1962 and 2013, Imja Lake expanded from 0.03±0.01 to 1.35±0.05 km2 at a rate of 0.026±0.001 km2 a-1. The mean glacier-wide flow velocity was 37±30ma-1 during 1992–93 and 23±15ma-1 during 2013–14, indicating a decreasing velocity. A mean elevation change of –1.29±0.71ma-1 was observed over the lower part of the glacier in the period 2001–14, with a rate of –1.06±0.63ma-1 in 2001–08 and –1.56±0.80ma-1 in 2008–14. We conclude that the decrease in flow velocity is mainly associated with reduced accumulation due to a decrease in precipitation during the last few decades. Furthermore, glacier ablation has increased due to increasing maximum temperatures during the post-monsoon months. Decreased glacier flow velocities and increased mass losses induce the formation and subsequent expansion of glacial lakes under favourable topographic conditions.
This article describes how the concept of Tourism Carrying Capacity (TCC) has shifted from a uni-dimensional approach to incorporating environmental, social and political aspects. This shift is ...demonstrated by a study of a large, internationally popular protected area used by trekkers, the Mt. Everest Region, where qualitative data collected from visitors was combined with environmental modeling using a participatory framework. Tourist satisfaction showed positive margins for further tourist industry expansion, but current environmental conditions limit growth and further development. Space and time dimensions were also considered. We observed that the limits on growth and further development can be manipulated, with a certain degree of flexibility, through investments and regulatory measures. We hypothesized that TCC can play an important role in the management of protected areas only if it is viewed as a systematic, strategic policy tool within a planning process rather than as a unique, intrinsic number that is not modifiable. We conclude that to translate the strategy into action using standard measures, further investigation is needed to balance the various TCC components as a part of a decision-making framework that includes the integration of different cultural approaches and policy needs.
•We examine both Social and Environmental Carrying Capacities in a protected area.•We contribute to revive the present debate on growth limits in tourist destinations.•Tourism Carrying Capacity is a multi-dimensional, systematic, strategic policy tool.•The growth limit can be modified by management policies.•A protected area could present multiple growth limits both temporally and spatially.
Over the past two decades, we observed a substantial rise in ionic content that was mainly determined by the sulfate concentration at 20 remote high elevation lakes located in central southern ...Himalaya. At LCN9, which was monitored on an annual basis for the last 20 years, the sulfate concentrations increased over 4-fold. Among the main causes, we exclude a change in the composition of wet atmospheric deposition, as well as a possible influence of decrease in seasonal snow cover duration, which could have exposed larger basin surfaces to alteration processes. Glacier retreat likely was the main factor responsible for the observed increase of sulfate concentrations. We attribute this chemical changes mainly to the sulfide oxidation processes that occur in subglacial environments. Moreover, we observe that the weakened monsoon of the past two decades has only partially contributed to the lakes enrichment through runoff waters that are more concentrated in solutes or lowering the water table, resulting in more rock exposed to air and enhanced mineral oxidation.
This study provides a complete mapping (October 2008) of glacial lakes and debris-covered glaciers in the Mount Everest region. These types of analyses are essential in studies of the impact of ...recent climate change, and therefore the uncertainty of measurements is discussed with the aim of creating a reference study for use when glaciers and lakes are delineated using remote sensing imagery. Moreover, attention is focused on conditions related to the formation of lakes, which is the greatest evidence of the impact of climate change at high altitudes characterized by debris-covered glaciers. Regarding the formation process of supraglacial lakes, our findings confirm that the slope of the glacier where lakes are located is primarily responsible for the low flow velocity of this zone. Otherwise, this study is novel in its identification of a further boundary condition. The slope of the glacier upstream is able to influence both the low flow velocity and the high ablation rates at the glacier terminus. In fact, the imbalance between the two glacier zones generates the down-slope passage of debris, snow and ice. We found the slope of the glacier upstream to be inversely correlated with the relevant total surface of the lakes downstream. The multiple regression model developed in this study, considering the slopes of the two glacier areas distinctly, has been able to predict 90% of the supraglacial lake surfaces. Concerning the surfaces of lakes not directly connected with glaciers (unconnected glacial lakes), we found they are correlated with the dimensions of their drainage basin, whereas no correlation was found with the glacier cover in the basin. Considering that the evaporation/precipitation ratio at these altitudes is approximately 0.34, the evolution of these lakes appears to be a helpful sign for detecting the precipitation trend of these high-altitude regions.
►The glacier slopes upstream and downstream are able to predict 90% of the supraglacial lake surfaces. ►The evolution of lakes not directly connected with glaciers can be used as an helpful sign of the precipitation trend. ►The uncertainty of measurement when satellite imagery is used for mapping glacial lakes and glaciers is assessed in this study.
Availability and applications of open-source data for disaster risk reductions are increasing. Flood hazards are a constant threat to local communities and infrastructures (e.g., built-up environment ...and agricultural areas) in Nepal. Due to its negative consequences on societies and economic aspects, it is critical to monitor and map those risks. This study presents the open access earth observation (EO) data, geospatial products, and different analytical models available for flood risk assessment (FRA) and monitoring in Nepal. The status of flood risk knowledge and open-source data was reviewed through a systematic literature review. Multispectral optical data are widely used, but use of microwave data is extremely low. With the recent developments in this field, especially optical and microwave data, the monitoring, mapping, and modeling of flood hazards and risk have been more rapid and precise and are published in several scientific articles. This study shows that the choice of appropriate measurements and data for a flood risk assessment and management involves an understanding of the flood risk mechanism, flood plain dynamics, and primary parameter that should be addressed in order to minimize the risk. At the catchments, floodplains, and basin level, a variety of open data sources and models may be used under different socioeconomic and environmental limitations. If combined and analyzed further, multi-source data from different models and platforms could produce a new result to better understand the risks and mitigation measures related to various disasters. The finding of this study helps to select and apply appropriate data and models for flood risk assessment and management in the countries like Nepal where the proprietary data and models are not easily accessible.
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