Journal of Environment Sciences

Relation between Modis-based Aerosol Optical Depth and Particulate Matter in Kathmandu using Regression Model

Saurav Timilsina — 2023-07-14

Ambient fine Particulate Matters have been linked to various adverse health outcomes. Exposure to the high level of such particles would increase the risk of premature death, especially for people with weak immune systems, such as children and elder people. This research derives the relation between particulate matter and AOD from the Regression model on the seasonal (Pre-monsoon season (March 2020) and winter season (December 2019) basis of Kathmandu. Here two models have been developed one linear single-variable regression model and the other multivariable regression model. For the multivariable regression model, meteorological factors like Wind speed, Temperature, and Relative Humidity were adopted from the underground and the Planetary boundary layer height was simulated from WRF. Particulate matter (PM_2.5) was adopted from the US Embassy air quality station and MODIS Level 2 AOD having 10 km resolution was analyzed for regression modeling. The linear single variable and linear multivariable regression model were developed seasonally one from December 1^st to December 31^st, 2019 (winter season) and the other from March 1^st to March 31^st, 2020 (Pre-monsoon season) using Python. The seasonal correlation coefficient of these two models was obtained. In both seasons, the multivariable linear regression model showed a good correlation between AOD and Particulate Matter R² (Pre-monsoon) = 0.72657, R² (winter) = 0.4687) compared to the single variable regression model having R² (Pre-monsoon) = 0.45, R² (winter) = 0.133). In both these regression models using the evaluated regression coefficients, two seasonal equations were derived from which Particulate Matter can be estimated.

Sidewalk Landscape Structure to enhance Pedestrian Thermal Comfort in Kathmandu Metropolitan City

Arpana Shakya — 2023-07-14

The thermal comfort of pedestrians in the outdoor spaces of urban areas has deteriorated due to the urban densification. The street being a major outdoor space that can promote physical activity, and especially with the emerging concept of walkable cities, thermal comfort in streets should be given utmost importance. Thermal comfort for pedestrians is the absence of any sense of discomfort when interacting with the outdoor thermal environment. This paper aims to evaluate the effectiveness of various landscape measures (trees and pavements) to enhance pedestrian thermal comfort on sidewalks. The study has adopted the quantitative approach and used the simulation and questionnaire survey as methodological tools to meet its objectives. The study was conducted on both sidewalks of Durbarmarg, one of the dense and busy streets of Kathmandu. The microclimatic modeling software ENVI-met 5.03 lite was used for the simulation. The results of the simulation showed that increasing the leaf area density (LAD), tree canopy size and height can reduce the air temperature by 0.2°C and Mean radiant temperature by 4.86°C. Among the various pavement materials in various scenarios for the simulation, the light concrete pavement showed the highest decrease in terms of the air temperature (0.579°C) however the mean radiant temperature was highest (7.22°C) for the same material. Hence, high reflective surfaces reduce the surface /air temperature but it increases the mean radiant temperature and hence they might not be appropriate for the thermal comfort of pedestrians. The paving materials which showed a decrease in both air temperature and mean radiant temperature were porous concrete, flagstone, and brick pavers. The study concludes that proper selection of pavement materials and high leaf area density of trees can enhance the thermal comfort for pedestrians on the sidewalks of Kathmandu.

Floristic Composition, Diversity and Carbon Stock Along Altitudinal Gradient in Hasantar Community Forest, in Nagarjun Municipality, Kathmandu District

Pranil Pradhan — 2023-07-14

This study has attempted to estimate above and below ground biomass along altitudinal gradient and examined the relation between carbon stock and diversity indices. The study area was categorized into three sections based on the elevation interval of 200m ranging from 1300m to 1900m. Vegetation sampling was performed in 33 circular plots, each of 500m² and was selected based on systematic random sampling. Phyto-sociological parameters and above and below ground biomass and total carbon stock were calculated for each section of the study area. Carbon stock showed negative and insignificant relation with species evenness (r=-0.24, P= 0.17) and positive but insignificant relation with species richness (r=0.17, p=0.34) and Simpson’s index of dominance (r=0.18, P=0.31). However, humped shaped and statistically insignificant (P=0.93) relationship was observed between Shannon diversity index and carbon stock. This research results provide baseline information for the management of Hasantar community forest.

Woody species diversity and assemblage in different forest management stands of central Nepal

Pradeep Ghimire — 2023-07-14

Various forest management strategies are in place for the conservation of forest ecosystems across the globe. Nepal is also implementing different forest management and restoration practices and has various impacts on vegetation characteristics. This study aims to compare the richness and diversity of woody plant species, and variability in abundance of woody species assemblages in different forest management stands, viz. restored stands inside Buffer Zone Community Forest (BZCF), natural stands of BZCF and core stands of Parsa National Park. Thirty sampling plots of 30 m × 30 m were laid on each stand, maintaining at least 50 m distance between the plots, where woody plant species having height 1.5 cm was identified and their DBH measured. Species composition was assessed comparing Importance Value Index (IVI) of woody plant species across the forests. Similarly, species diversity and structural diversity across stands were determined using Shannon Diversity index and basal areas of the plant species were calculated. The study showed Shorea robusta and Lagerstroemia parviflora with highest frequency (>80%) in all the sites, and the species diversity was highest in the core stands inside the national park followed by the natural stands of BZCF, and the restored stands of BZCF. Basal area of overall species and density of S. robusta were, however, highest on the restored stands of BZCF, whereas overall density was highest in the natural stands of the BZCF. The study revealed that the forest management practices need improvement in enhancing the plant species diversity of the ecosystems. We recommend to assess the functional attributes of the different forest management stands to evaluate the effectiveness of forest management strategies.

Flood Loss Assessment - A Case Study of Dordi Basin, Gandaki, Province

Satyam Kumar Chaudhari — 2023-07-14

Hydropower plants are a quintessential source of clean and economical energy, serving as the primary preference for renewable energy technologies for many governments owing to their unparalleled ability to deliver dependable baseload power with negligible fluctuation. However, despite their numerous benefits, the construction and operation of these plants pose a significant threat to the population living in the river basin and the equipment involved. The damage caused by flooding can have devastating and long-lasting impacts on the area, leading to severe economic losses and a prolonged period of recovery. In the case of the Dordi Rural Municipality, a study was carried out, which revealed that the Upper Dordi Hydropower Plant Headwork and Super Dordi Hydropower Plant inlet were ravaged by a ruinous flood, which resulted in the loss of twenty million equipment and eleven workers die. The cause of the flood was attributed to the upstream landslide blockage, which eventually led to the sudden bursting of the blockage and subsequent flooding. While the compensation of the workers was provided by the District Administration Office, Lamjung, and Dordi Rural Municipality through their incurrence policy, the study underscores the urgent need to establish a highly frequent flood warning system to alert the hydropower station and the local community. Additionally, the scouring and deposition process in the river channel was observed in detail, and the data analysis indicates no significant relationship between discharge and rainfall, emphasizing the importance of proactive measures to prevent future flooding events.

Wildlife restoration in Nepal: tracking the conservation translocations in the country

Chandra Mani Aryal — 2023-07-14

Negative consequences of human impacts on biodiversity are undisputable and inadequate efforts in managing biodiversity have been realized across the globe. The present biodiversity crisis, including burgeoning effects of climate change, therefore, has warranted restoration actions in place. Conservation translocation, one of the effective measures of restoration, involves the individuals of species deliberate movement from one habitat to another, particularly animal species. Nepal has been practicing the conservation translocations for more than four decades. However, details of conservation translocation events and outcomes are not well documented. This article aims to explore the status and issues of conservation translocation in Nepal. For the purpose, we reviewed seven protected area management plans and nine species conservation action plans available in public domain along with related peer reviewed journal articles. We documented the conservation translocation of Blackbuck, Gharials, Swamp deer, Greater One Horned Rhino, Elongated tortoise, Narrow Headed Soft Shell Turtle, Wild Water Buffalo and Vulture. Adoption of feeble adaptive management framework and ad hoc approach of wildlife translocation has left many rooms for improvement in the translocation strategies of Nepal. This is largely exemplified by the improvement required in Vulture Breeding Center, Swamp deer and Wild water buffalo translocations to Chitwan National Park, and Blackbuck translocation to Bardia National Park. For many species, data and information are limited to evaluate the wildlife restoration outcomes independently.

Impacts of Earthquake and Earthquake-induced Disasters on Community Forests in Nepal

Man Kumar Dhamala — 2023-07-14

Managing the commons is a challenging issue during crisis such as earthquakes. We considered four community forests, two from Gorkha and one from each of Dolakha and Sindupalchowk districts that were major earthquake affected areas. The study made use of ecological and socioeconomic survey techniques to assess the impacts of earthquake on community forests and management status of those forests. We calculated density of seedling, sapling and tree species and diameter size distribution of trees. We also analysed the forest status changes before and after the earthquake events and distribution of timber and fire wood in the community forest user groups. Seedling, sapling and adult trees number wise regeneration status of trees was good in all the studied forest whereas DBH size class diagram were bell shaped indicating unsustainable regeneration. Most of the respondents reported poor forest management after the earthquake and wood distribution has drastically increased after the earthquake 2015. From this study it is recommended that community forest management practices should be resilient to disasters and prepare alternative solutions to lower the pressure on forest products so as to maintain sustainable regeneration of forest trees and regular supplies of resources in future.

Land use land cover change and its implication on water fowl diversity: A case study of Taudaha Lake, Kathmandu, Nepal

Ananta K. Karki — 2023-07-14

The wetlands of Nepal are well known for unusually rich biodiversity. Taudaha is famous for winter migrant water fowls as far as from Siberian. The natural form of Taudaha has been neglected and it is surrounded by concrete homes instead of trees and paddy field. Land use change is often regarded as one of the main reasons for habitat degradation and subsequent decrease in migratory birds’ population. This article aims to quantify the land use change scenario in and around the lake area using GIS tool. Google images from February 2004 and April 2022 were obtained from “Google Earth Pro” software and used to prepare the land use map by using “QGIS 3.12” software. The cultivated land covered about 73.42% of the total study area followed by settlement (8.61%), vegetation (8.02%) and the lake (9.95%) itself in 2004. But 18 years later, in the year 2022, Taudaha is gradually surrounded by urban areas. The cultivated land has been changed to be settlement areas. The cultivated land has decreased for construction of houses, hotels and resorts. Human activities in hotels and resorts near the lake area have caused distraction to migratory birds visiting the lake. This is causing degradation of habitat of the migratory bird species. Literatures showed the declining number of migratory bird species visiting the lake areas during winter.

Estimation of soil erosion using the Revised Universal Soil Loss Equation (RUSLE) in Relation to Landslides in Mid-hills of Nepal

Lalit Pathak — 2023-07-14

An attempt has been made in this research to assess soil erosion and its spatial distribution by the revised universal soil loss equation (RUSLE) model at Rangun Khola Watershed, western Nepal. The erosion factors were acquired from multiple sources (Satellite images, ALOSPALSAR DEM, SOTER soil database, Esri 2020 land cover map, rainfall database of DHM) and an integrated analysis was carried out in raster format of GIS. A landslide inventory was generated on the basis of satellite images and past literature to validate soil erosion intensity in the area. The result map of the RUSLE model was categorized into six levels based on the erosion severity, and 9.06 % of the area was found to be under extremely severe soil erosion risk (> 80 ton ha^”1year^”1) indicating urgent consequences. The frequency ratios for each level of potential erosion susceptible to landside exhibited a linear relationship depicting reasonable and satisfactory level of agreement between the landslide event/location data and the erosion map that validates the model result. The result of this study will be helpful to detect the sensitive zones presenting a priority of protection and offer valuable information that aids decision-makers and user agencies in creating adequate conservation planning programs to stop soil erosion and maintain the natural balance.

Land Use and Cover Change Detection in Shankharapur Municipality, Kathmandu Using Spectral Indices

Rabin Shakya — 2023-07-14

The surging increase of the urban population has been accompanied by a sharp increase in urban built-up areas. The growth of population contributing to rapid expansion of built-up area in recent decades has caused a substantial Land Use Land Cover (LULC) change across Nepal and in particular Kathmandu Valley (KV). In this study, a Normalized Difference Vegetative Index (NDVI) and Normalized Difference Built-up Index (NDBI) was applied to three Landsat imagery collected over time (2002, 2013, and 2022) and one Sentinel-2 imagery that provided recent and historical LULC conditions for, Shankharapur municipality that lies in the eastern part of Kathmandu. The three-land use land cover categories were identified and mapped from the value of NDBI and NDBI. We found that over a period of 20 years (from 2002 to 2022), the Shankharapur municipality has lost 14.64% and 25.97% of its forests and sparse vegetation, and increase in the settlement/open land by 5.48% and 226.73% as indicated by NDVI and NDBI for Landsat imagery respectively. The increase in settlement/open land can be summed to the augmented activities like constructing new building and increase forest and land defragmentation including construction of road and land planning to fulfill the demand of influx of people after the earthquake of 2015. The results of NDVI and NDBI from Sentinel-2 imagery also support the increase in settlement/open land and decrease in forest and sparse vegetation. Also, agriculture cover increased by 4.25 sq.km between 2002 to 2013 and increased by 4.85 sq.km. from 2013 to 2022 as indicated by NDVI derived from Landsat imagery. However, the significant amounts of losses of forest and sparse vegetation during 20 years have been absorbed by the expanding urbanized areas and agriculture land as more land is subjected to the built-up and land planning along with the wood-logging as a result of aftermath of the earthquake, 2015, where population has increased by 19.4 % in the span of 10 years from 2011 to 2021 and is never retreating in terms of changing land cover. Therefore, such trends if unchecked can result in loss of biodiversity and ecosystem services associated with deteriorating conditions for human well-being.

Identification of mammalian indicators of climate in Chitwan Annapurna Landscape (CHAL) to assess climate change

Ranjana Regmi — 2023-07-14

The consequences of climate change on species and ecosystems are evident, and the landscape of Nepal does not remain unaffected. Himalayan region is climate sensitive, even a tiny fluctuation in climate can markedly affect numerous species and their habitats. Moreover, the Himalayan region is inhabited by some of the most threatened and endangered biodiversity on Earth, including habitat specialists and endemic species, which may accelerate the extinction of some species. Hence, species affected by climate change should be monitored and identified as faunal indicators of climate change in (Chitwan Annapurna Landscape) CHAL. For that, we compared studies conducted by the National Trust for Nature Conservation (NTNC) and World Wildlife Fund for Nature (WWF Hariyo Ban Program). First, we identified the common and overlapping species. Second, we identified the critical species for climate monitoring based on habitat range, elevation, role as habitat specialist/generalist, and impact observed in previous studies based on the species occurrence in that region. Species with a long-life span, specialist habitat type, and short home range are exposed to climate change for extended periods, making them more vulnerable as per the literature. In particular, our results demonstrate that the one-horned rhinoceros found in the lower belt of Nepal and snow leopard, and pika, being habitat specialists, with low reproductive rate and cannot tolerate change in temperature experience a high impact owing to climate change and can be used as indicators of climate change. In addition to that Assasames Monkey and elephant has medium impact and hence can be considered as the indicator to monitor climate change. However this study does not incorporate specific species-based study regarding the impact of climate change which is required to assess climate change sensitivity to facilitate global wildlife protection.

Assessing and Comparing Environmental Assessment Pathways in Nepal

Manoj Aryal — 2023-07-14

National Environmental Impact Assessment Guideline (NEIAG), 1993, is the major guiding legal document for the project level environmental assessment in Nepal which has provided the concrete methods for impact identification, prediction and evaluation for the proposals to be implemented. Environment Protection Act, 1997 (EPA-1997) and Environmental Protection Regulations, 1997 (EPR-1997) highlighted the categories and thresholds of the proposals requiring Initial Environmental Examination (IEE) and Environmental Impact Assessment (EIA), requirements of public hearing particularly for EIA, environmental monitoring by concerned ministries for IEE and Ministry of Environment (MoE) for EIA, Environmental Audit for EIA, punishments of five to twenty-fifty lakhs for implementing proposals without the approval of Environmental Assessment (EA) reports, timeline of fifteen days public notice, approval of IEE report within twenty-one days and sixty days for EIA report, provisions for Supplementary Environmental Impact Assessment (SEIA) and brief formats of the reports. Environment Protection Act, 2019 (EPA-2019) and Environment Protection Regulations, 2020 (EPR-2020) has advanced the existing provisions of EPA-1997 and EPR-1997. Brief Environmental Study (BES) has been added as a new project level environmental assessment required for the particular projects. EPA-2019 and EPR-2020 has empowered the provincial and local governments for conducting and approving the proposals to be executed in respective level of governments. Public hearing is made mandatory for all levels of environmental assessments. Proposals implemented without the approval and/or violating the provisions of approved reports are charged with the amount of fine up to five lakhs for BES, up to ten lakhs for IEE, and up to fifty lakhs for EIA. Requirement of Strategic Environmental Analysis (SEA) for plans, policies and programs is a new legal concept of environmental assessment at strategic level. The timeline for approval of Scoping Document (SD), Terms of Reference (ToR), BES and IEE report is within fifteen days of report submission, within sixty days of report submission for EIA report, submission of final BES, IEE and EIA report is mandatory within two years of SD and ToR approval and initiation of proposal implementation is within three years of EA report approval. The recent legal provisions also have provided room for updating of BES report, IEE report and Environmental Management Plan (EMP) as per the requirement of the proposal implementation. Blacklisting the consultants for not assuring the standards of reports as required by the government, detail formats of reports, language of the reports to be in Nepali language and alternative analysis of the mitigation measures for particular impact and suggestion of the best mitigation measures are some additional provisions in the newer legal provisions.