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1
Tamrakar, Naresh Kazi, and Ramita Bajracharya. "Basinal and planform characteristics of the Kodku and the Godavari Rivers, Kathmandu, Central Nepal." Bulletin of the Department of Geology 15 (January 21, 2013): 15–22. http://dx.doi.org/10.3126/bdg.v15i0.7414.
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The rivers of the Kathmandu Basin are vulnerable to flash floods and disturbances caused by anthropogenic as well as climatic changes. Two southern tributaries of the Bagmati River: the Kodku and the Godavari Rivers, have been considered for their (i) watershed-scale geomorphic parameters such as relative relief, drainage texture and stream order, (ii) stretchscale planform parameters such as sinuosity (K), meander belt width (Wblt), meander wavelength (Lm) and radius of curvature (Rc), and (ii) longitudinal profiles and slopes. Both Kodku and the Godavari Rivers are elongate basins with wide ranges of the watershed-scale parameters. The Godavari River is longer, larger and more sinuous compared to the Kodku River. The development of the patterns of the fifth order main stem stretches of both rivers with respect to the stream slopes, and asymmetric patterns of the meander loops indicate anomalous growth of the river stretches. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7414 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 15-22
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Pandey, Vishnu Prasad, Dibesh Shrestha, Mina Adhikari, and Shristi Shakya. "Streamflow Alterations, Attributions, and Implications in Extended East Rapti Watershed, Central-Southern Nepal." Sustainability 12, no. 9 (May 8, 2020): 3829. http://dx.doi.org/10.3390/su12093829.
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Streamflow alteration and subsequent change in long-term average, seasonality, and extremes (e.g., floods and droughts) may affect water security, which is a major concern in many watersheds across the globe. Both climatic and anthropogenic activities may contribute to such changes. Therefore, this study assesses: (i) Streamflow and precipitation trends to identify streamflow alterations in the Extended East Rapti (EER) watershed in central-southern Nepal; (ii) relationship of the alterations to climatic and anthropogenic sources; and (iii) implications of streamflow changes to the socio-environmental system. The trends in streamflow were analyzed for pre-and post-1990 periods considering the abrupt shift in temperature trend in 1990. Results showed a general decreasing trends in discharge post-1990 in the EER watershed. Human activities have significantly contributed in altering streamflow in the EER. Human-induced streamflow alterations have affected the water availability, food security, river health, aquatic biodiversity, and groundwater abstraction in the EER watershed.
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Tamang, Niraj Bal, Naresh Kazi Tamrakar, Milan Magar, and Mahesh Raut. "Fluvial morphology and sediment transport of the Malekhu Khola, Central Nepal Lesser Himalaya." Bulletin of the Department of Geology 18 (January 23, 2017): 35–48. http://dx.doi.org/10.3126/bdg.v18i0.16455.
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Areas near the rivers and streams have been widely used for settlement, development works and agriculture due to availability of the resources such as water, aggregates and comparatively easier terrain. It is very important to understand prevailing fluvial conditions for sustainable output. The fluvial conditions of the Malekhu Watershed including the river characteristics, sediment transport and sediment dynamics were studied. Ten river transects and the corresponding segments of the Malekhu Khola were surveyed for cross-sections and longitudinal profiles. Samples were collected in each of the transects and were analysed for suspended sediment concentration. The riverbed sampling was made using Wolman’s pebble count for establishing grain size distribution. Manning’s roughness coefficients were determined to estimate discharge. The study shows that the Malekhu Khola is a sixth order stream. It has been classified into A4-, B4- and C4-type streams. The hypsometric analysis of the Malekhu Watershed shows that it is in mature stage of erosion. Sediment grain size slightly increases downstream but sorting remains extremely poor to moderately poor. The Malekhu Khola shows eroding tendency at 1.2 km, 16.6 km and 20 km from the origin and brings larger particles only during high flow period at the remaining transects. Mean Suspended Sediment Concentrations (SSC) for the Malekhu Khola was 72.14 mg/L, and it increases with increasing discharge and increasing watershed area and is related to velocity of the river, mining activities and local tributaries.Bulletin of the Department of Geology, Vol. 18, 2015, pp. 35-48
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Tamang, Niraj Bal, and Naresh Kazi Tamrakar. "Morphology and dynamics of the Malekhu Khola, Dhading district, central Nepal." Journal of Nepal Geological Society 50, no. 1 (December 21, 2016): 133–42. http://dx.doi.org/10.3126/jngs.v50i1.22873.
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Rivers have always been an indispensable part of the human civilization. They play a vital role in daily life purposes to big engineering constructions such as dams, reservoirs or hydropower projects. It is mandatory to understand the morphology and dynamics of the river before initiating any projects for easier planning and to prevent possible damage to structures. The Malekhu Khola area is one of the potential areas for urbanization and has already been undergoing development of settlement and other infrastructures. This paper describes the morphology and dynamics of the Malekhu Khola to classify and characterize the river's behavior and competency. The Malekhu Khola is a sixth-order river having its total length of 24.83 km, watershed area of 101.28 km2 and the average gradient of 0.041 m/m. Various morphological parameters were measured with the aid of topographic maps, aerial photographs and Geographic Information System (GIS). The hydraulic parameters, channel sediment and slopes were measured at 10 different transects sites through field surveys. The river was classified using the Rosgen's Level II criteria. The river reaches have been classified as A4-, B4- and C4-type streams. A4- and B4-type streams are moderate-gradient gravelly and low sinuosity rivers whereas C4-type streams are low-gradient gravelly meandering river. The Malekhu Khola gradually changes from A4- to B4-type streams up to 12 km downstream, and then to C4-type stream further downstream, but B4-type streams reappear within the distance of 15 km to 19 km from the origin. This study presents temporal changes in river channel, and flow competence and aggrading/degrading potential evaluation of the Malekhu Khola.
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Paudel, Shambhu, Prabhat Pal, and Harish Singh Dhami. "Restructuring Integrated Watershed Management Models for the Federal Democratic Regime of Nepal." Journal of Forest and Natural Resource Management 1, no. 1 (February 10, 2019): 69–76. http://dx.doi.org/10.3126/jfnrm.v1i1.22654.
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Recent political envision has redesigned the administrative units of Nepal into federal states with the aim of decentralizing the power to ensure the process of rapid sustainable development. As a consequence, all the public service agencies need to restructure their delivery units for achieving goals targeted by the newly adopted administrative regime plan. With the aim of recommending the best watershed management models for this changing context, this paper aims to review existing watershed management models applied in different continents like European union, African union and the United States where they have already adopted this watershed management plans into their federal states or countries union successfully. Although they are geographically distinct and economically advanced, the major approach adopted is a river basin approach with the clear legislative framework. This approach is highly succeeded between interstate (or between member countries) because of political or interstate commitments for the common pool resource water. Clear policies and commitments between member countries or interstate greatly improved the function of this mechanism. With the light of those experiences in the field of watershed management plan adopted in federal or union countries, river based integrated management plan balancing efforts between interstates seems best models in the world, and is also proposed for the new federal republic of Nepal.
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Dahal, Ngamindra, Uttam Shrestha, Anita Tuitui, and Hemant Ojha. "Temporal Changes in Precipitation and Temperature and their Implications on the Streamflow of Rosi River, Central Nepal." Climate 7, no. 1 (December 28, 2018): 3. http://dx.doi.org/10.3390/cli7010003.
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Nepal has experienced recent changes in two crucial climatic variables: temperature and precipitation. Therefore, climate-induced water security concerns have now become more pronounced in Nepal as changes in temperature and precipitation have already altered some hydrological processes such as the river runoff in some river systems. However, the linkage between precipitation patterns and streamflow characteristics are poorly understood, especially in small rivers. We analysed the temporal trends of temperature, precipitation, and extreme indices of wet and dry spells in the Rosi watershed in Central Nepal, and observed the temporal patterns of the streamflow of the Rosi river. We also examined the linkages between the average and extreme climate indices and streamflow. We found that the area has warmed up by an average of 0.03 °C/year, and has seen a significant decline in precipitation. The dry spell as represented by the maximum length of the dry spell (CDD) and the magnitude of dryness (AII) has become more pronounced, while the wet spell as represented by the number of heavy rainfall days (R5D) and the precipitation intensity on wet days (SDII) has diminished significantly. Our analysis shows that recent changes in precipitation patterns have affected the streamflow of the Rosi river, as manifested in the observed decline in annual and seasonal streamflows. The decrease in the availability of water in the river is likely to have severe consequences for water security in the area.
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Tamrakar, Naresh Kazi, and Dharmendra Khakurel. "Lithologic and morphometric characteristics of the Chure River Basin, Central Nepal." Bulletin of the Department of Geology 15 (January 21, 2013): 35–48. http://dx.doi.org/10.3126/bdg.v15i0.7416.
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The Chure River Basin (CRB) is a small basin (width 5.75 km, length 9.74 km, perimeter 32.35 km and area 35.23 km2) with three sub-watersheds, and is crossed by the Tribhuvan Highway that may be threatened by riverine and allied processes. The geology and morphometry of the basin were studied to search for status of the basin development andriver dynamism. The Chure River is a sixth order river fed by rainstorm, and has length ratio of 2.79, indicating nearly three times the average length of its fifth order segment, showing notable competency. The mean bifurcation ratio of the Chure River is 3.20, showing immature nature of the CRB. Drainage texture (DT) varies from moderate (0.64–0.96) to very fine (0–0.32). The Chure River is sinuous (K =1.18).The relative relief (RR) is moderately low (15–30) to moderately high (120–240) and dissection index (DI) is moderate (0.2–0.3) to high (0.3–0.4). The CRB carries varied lithology; gravelly to coarse sandy and medium sandy and muddy, from the north to the south extension of the basin. Fine to very fine DT found in large areas because of loosely consolidated and soft lithology. Even where rocks are stiff, the presence of discontinuity has perhaps influenced the DT. Very fine to fine DT coupled with elongate nature of the basin (as indicated by low value of form factor, 0.37) is vulnerable to greater competency of the river during high rainfall.RR slope and DI are found to be high in the cliff- forming lithology (stiff and well cemented), and low in other areas. High dissection, high slopes and high relief show active and immature nature of the CRB, indicating susceptibility of further incision of the Siwalik Hills and aggravation of erosion and slope movements by the immature rivers in the CRB. Presence of knick points along the river profile reflects affinity of the river to incision. The sinuosity, radius of curvature, and bifurcation ratio, all indicate immaturity of the basin. The hypsometric analysis indicates inverse relationship between the elevation and the cumulative %area, showing active erosional condition of the basin. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7416 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 35-48
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Tamrakar, Naresh Kazi, Ramita Bajracharya, Ishwor Thapa, Sudarshon Sapkota, and Prem Nath Paudel. "Morpho-hydrologic parameters and classification of the Kodku River for stream stability assessment, southern Kathmandu, Central Nepal." Bulletin of the Department of Geology 16 (October 11, 2013): 1–20. http://dx.doi.org/10.3126/bdg.v16i0.8880.
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The Kodku River Corridor is one of the most potential corridors for future development of roads that would link the southern remote areas of the Kathmandu Valley to the inner core areas. River stability is of great concern as the unstable segment of river may pose threat on infrastructures, and adjacent cultivated lands and settlement areas. In this light, the preliminary assessment of the Kodku River as a part of the stability assessment was undertaken. The broad level geomorphic and hydrologic parameters, and Level I and II classifications of the river were made to assess for stability condition.The Kodku River is a fifth order stream, extending for about 15.86 km and its watershed covering an area of 35.67 sq. km. The relative relief is extremely high to low, and diminishes with change of landforms from steep terrain in the southern part to the gentle sloped terraces in the northern part of the watershed. Drainage texture is fine to very coarse, from the southern to the norther parts of the watershed. All the stream segments are sinuous (K = 1.2) whereas the Arubot Segment is the highly meandering (1.7). Both meander wavelength and belt width increase with increasing stream order. Five types of valleys have been distinguished; I, II, IV, VI, and VIII type valleys. Based on valley type distribution, channel pattern, shape and channel slope, the stream segments have been classified using Level I assessment as ‘B’ type, ‘C’ type and ‘Aa+’ type streams. The ‘B’ type streams are all located in the third order segment. Except the ‘Aa+’ type stream, all the fifth and fourth order stream segments belong to ‘C’ type streams. Width/Depth ratio varying between 10.5 and 29.5 indicates laterally unstable channel segments. The bank height ratio, which varies between 1.6 and 2.4, indicates moderate incision and shows vertical instability of streams. The Badikhel Segment is relatively more entrenched (1.7) while the Taukhel Segment is the least entrenched (7.1). Since Entrenchment Ratio exceeds 1.6, the stream segments are considered to have moderate to low entrenchment. Based on the bed material load, the Kodku River is a gravelly mixed-load river, in which pebbles to silt/clay occur. Level II classification distinguishes three-types of streams; ‘B4c” type (Badikhel Segment), ‘C6c’ type (Taukhel Segment), and ‘C4c” type (Arubot, Thaiba and Harisidhi Segments). The ‘B4c’ type stream has tendency of vertical instability. The ‘C6c” and ‘C4c” type streams have shallow and wide meandering channels with well developed flood plains and lateral bars, and reflect tendency of lateral instability.DOI: http://dx.doi.org/10.3126/bdg.v16i0.8880 Bulletin of the Department of Geology Vol. 16, 2013, pp. 1–20
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Ha, S. R., and D. Pokhrel. "Water quality management planning zone development by introducing a GIS tool in Kathmandu valley, Nepal." Water Science and Technology 44, no. 7 (October 1, 2001): 209–21. http://dx.doi.org/10.2166/wst.2001.0427.
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This research was conducted to identify the critical pollution (BOD, TN, TP) areas and to develop the priority mitigation zone for the Bagmati River pollution in the Kathmandu valley, Nepal. A GIS tool was used to define and identify the critical pollution areas and sources. Pollution source information such as population, livestock, industry and land use were collected on the basis of the individual village boundary. The industrial, land use and living pollution were aggregated by the GIS overlay analysis capability to obtain the combined pollution load within the watershed. Priority areas for the mitigation of the pollution were defined considering the pollution loading rate, distance of stream from pollution source, and political, religious, and touristic values of the area. This research noticed that Kathmandu, Lalitpur and Bhaktapur municipalities are the major polluting areas and living beings are the major factors of Bagmati River pollution. Delivery ratio for the watershed was found to vary from 40-69% for BOD and nitrogen but the delivery of phosphorus was exceptionally high (92% at Gaurighat and 77% at Chovar) due to cremation activity of the Hindu religion on the riverbanks. Thus, the priority areas for the mitigation of the carbonaceous and nutrient source pollution were identified. At present the land use and industry impaired a very low contribution compared to the huge pollution load from the municipalities to the river system.
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Sah, Kamal, and Sushil Lamichhane. "GIS and Remote Sensing Supported Soil Erosion Assessment of Kamala River Watershed, Sindhuli, Nepal." International Journal of Applied Sciences and Biotechnology 7, no. 1 (March 26, 2019): 54–61. http://dx.doi.org/10.3126/ijasbt.v7i1.23307.
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This study analysed the situation of water-induced soil erosion in Kamala River watershed of Sindhuli, Nepal covering 23,194.33 hectares of land, extending from 85°58'11.6"E to 86°18'16.8"E longitude and 26°56'45.9"N to 27°5'44.4"N latitude. Revised universal soil loss equation was applied in GIS environment using the satellite-based data, field measurements, surveys and lab analysis. R factor predicted from the average annual precipitation. K factor based on the soil texture and organic carbon content. LS factors derived from the DEM of 20m resolution. C factor derived from the NDVI value extracted from Landsat 8 OLI imagery of the pre-monsoon season. P factor assigned according to the land cover of the study area. The study explored the massive diversity of erosion rates even within the narrow span of a landscape in the Churia range of the Himalayan foothills. As predisposed by the diversity of terrain and vegetation cover, and aggravated further by the dominance of silts in the texture of soils, soil erosion rate has been found to vary and noticeably occur in higher ranges of severity. Overall, total potential of soil loss in the watershed was 1.460 million tons/ year, out of which only 0.297 million tons of soil was estimated to be actually eroded from the watershed in the existing conditions. Conservation measures are advisable in the areas having severe soil loss. The resulting soil erosion rate map can be a guideline for developing sustainable land management strategy in the concerned and similar lower foothills of Himalayan mountain landscapes.
Int. J. Appl. Sci. Biotechnol. Vol 7(1): 54-61
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Howell, Jocelyn, Doug Benson, and Lyn McDougall. "Developing a strategy for rehabilitating riparian vegetation of the Hawkesbury-Nepean River, Sydney, Australia." Pacific Conservation Biology 1, no. 3 (1994): 257. http://dx.doi.org/10.1071/pc940257.
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Situated on the southeastern coast at 34�S 151�E, Sydney was established in 1788 as Australia's first permanent European settlement. Clearing of natural vegetation and environmental degradation associated with the country's largest population concentration over the past 200 years have severely affected the nearby Hawkesbury-Nepean River. A strategy for rehabilitation of the riparian vegetation to conserve and enhance the natural conditions remaining along the river, with particular emphasis on habitat and natural biodiversity, has been developed. The study area encompassed the most modified part of the river, where it passes alternately through 80 km of sandstone terrain, where the natural vegetation of waterside scrub backed by open-forest remains largely unchanged, and 135 km of floodplain terrain, where most of the indigenous tall open-forest has been cleared and associated wetlands have been greatly modified. Indigenous riparian zone vegetation was recognized as critical to the maintenance of river health, providing a reservoir of biodiversity as a major value, upon which other values, including enhancement of water quality, bank stablility and erosion control, depend. As 47 per cent of study area riverbank was found to have less than 25 per cent tree cover, the strategy recommended that all remnant native vegetation and remnant native trees along the river be protected and that a substantial long-term aim should be the establishment of a 50-metre wide strip of native riparian forest vegetation on each bank along the full length of the river, to be linked ultimately with other areas of natural vegetation on the floodplain. To provide practical resources for revegetation, the strategy assembled a botanical database, including maps showing present tree cover and the past extent of floodplain vegetation types, descriptions and locations of sites where significant native riparian vegetation remains, ecological information on approximately 300 locally indigenous riparian and wetland plant species, guidelines on selection of appropriate species, replanting methods and determination of priorities at both site and landscape scale.
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Pangali Sharma, Til Prasad, Jiahua Zhang, Narendra Raj Khanal, Foyez Ahmed Prodhan, Lkhagvadorj Nanzad, Da Zhang, and Pashupati Nepal. "A Geomorphic Approach for Identifying Flash Flood Potential Areas in the East Rapti River Basin of Nepal." ISPRS International Journal of Geo-Information 10, no. 4 (April 8, 2021): 247. http://dx.doi.org/10.3390/ijgi10040247.
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Basin geomorphology is a complete system of landforms and topographic features that play a crucial role in the basin-scale flood risk evaluation. Nepal is a country characterized by several rivers and under the influence of frequent floods. Therefore, identifying flood risk areas is of paramount importance. The East Rapti River, a tributary of the Ganga River, is one of the flood-affected basins, where two major cities are located, making it crucial to assess and mitigate flood risk in this river basin. A morphometric calculation was made based on the Shuttle Radar Topographic Mission (SRTM) 30-m Digital Elevation Model (DEM) in the Geographic Information System (GIS) environment. The watershed, covering 3037.29 km2 of the area has 14 sub-basins (named as basin A up to N), where twenty morphometric parameters were used to identify flash flood potential sub-basins. The resulting flash flood potential maps were categorized into five classes ranging from very low to very high-risk. The result shows that the drainage density, topographic relief, and rainfall intensity have mainly contributed to flash floods in the study area. Hence, flood risk was analyzed pixel-wise based on slope, drainage density, and precipitation. Existing landcover types extracted from the potential risk area indicated that flash flood is more frequent along the major Tribhuvan Rajpath highway. The landcover data shows that human activities are highly concentrated along the west (Eastern part of Bharatpur) and the east (Hetauda) sections. The study concludes that the high human concentrated sub-basin “B” has been categorized as a high flood risk sub-basin; hence, a flood-resilient city planning should be prioritized in the basin.
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Tiruwa, Durga Bahadur, Babu Ram Khanal, Sushil Lamichhane, and Bharat Sharma Acharya. "Soil erosion estimation using Geographic Information System (GIS) and Revised Universal Soil Loss Equation (RUSLE) in the Siwalik Hills of Nawalparasi, Nepal." Journal of Water and Climate Change 12, no. 5 (January 27, 2021): 1958–74. http://dx.doi.org/10.2166/wcc.2021.198.
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Abstract Soil erosion is one of the gravest environmental threats to the mountainous ecosystems of Nepal. Here, we combined a Geographic Information System (GIS) with the Revised Universal Soil Loss Equation (RUSLE) to estimate average annual soil loss, map erosion factors, compare soil erosion risks among different land use types, and identify erosion hotspots and recommend land use management in the Girwari river watershed of the Siwalik Hills. The annual soil loss was estimated using RUSLE factors: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover crops (C), and conservation practices (P), and erosion factors maps were generated using GIS. Results indicate highest total erosion occurring in hill forests (13,374.3 t yr–1) and lowest total erosion occurring in grasslands (2.9 t yr–1). Hill forests showed high to very severe erosion due to steepness of hills, open forest types, and minimal use of conservation practices. Also, erosion hotspots (>15 t ha–1 yr–1) occurred in only 4.2% of the watershed, primarily in steep slopes. Overall, these results provide important guidelines to formulate management plans and informed decisions on soil conservation at local to regional levels. While the study is the first effort to assess soil erosion dynamics in the Girwari river watershed, potential for application in other basins largely exists.
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Sapkota, Sudarshon, and Naresh Kazi Tamrakar. "Bank erosion and lateral instability hazard status of Kodku Khola, southeast Kathmandu, central Nepal." Journal of Nepal Geological Society 50, no. 1 (December 21, 2016): 95–103. http://dx.doi.org/10.3126/jngs.v50i1.22869.
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The northward flowing fifth order Kodku Khola confluences with the Manahara River in the southeast of Kathmandu, and has about 16.49 km stretch with 35.67 sq km watershed area. Many large civil engineering structures such as irrigation cannels, bridges, highways and roads are under construction, and are located along and around the river in the urbanizing Kodku Khola valley. Some sections of the river are of high erosion potential due to various reasons. Many human activities together with natural processes have led to bank erosion and channel shifting of the Kodku Khola. Thus, study of the river bank erosion and lateral instability is of great concern as unstable segments of the river may pose threat on civil engineering structures and adjacent agricultural lands. The river bank hazard potential and its variations were assessed in terms of its bank erosion and lateral instability (BELI) hazard indices by considering four parameters namely, bank erosion hazard index (BEHI), near bank stress index (NBSI), lateral instability hazard index (LIHI), and anthropogenic disturbance factors (ADF). For this, thirty nine locations were surveyed throughout the river and assessed the BELI hazard levels. This paper evaluated the BELI hazard levels and channel shifting condition of the Kodku Khola.
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Yamaha, Tomom, Hideako Motoyama, and Kadcha Bdr Thapa. "Mass Balance Study of a Glacier System from Hydrological Observations in Langtang Valley, Nepal Himalaya." Annals of Glaciology 6 (1985): 318–20. http://dx.doi.org/10.3189/1985aog6-1-318-320.
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Hydrological and meteorological observations of river runoff, precipitation and air temperature were conducted 27 August to 26 October 1982, in Langtang Valley, Nepal Himalaya, whereby the mass balance of the glacier system there was estimated. Observed values suggest that (1) all glacier ablation and rainwater in the subwatershed of Langtang Valley drain into the river with the runoff coefficient of 1; (2) ablation of the glacier system can be estimated simply using a degree-day factor of 10 mm/degree-day; and (3) precipitation is considered uniform over the whole watershed. Assuming that the suggested phenomena persist throughout the year, records of monthly precipitation and monthly mean temperature in this valley, indicate that annual accumulation and ablation in the glacier system amount to 2000 ± 200 mm, respectively.
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Yamaha, Tomom, Hideako Motoyama, and Kadcha Bdr Thapa. "Mass Balance Study of a Glacier System from Hydrological Observations in Langtang Valley, Nepal Himalaya." Annals of Glaciology 6 (1985): 318–20. http://dx.doi.org/10.1017/s0260305500010788.
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Hydrological and meteorological observations of river runoff, precipitation and air temperature were conducted 27 August to 26 October 1982, in Langtang Valley, Nepal Himalaya, whereby the mass balance of the glacier system there was estimated. Observed values suggest that (1) all glacier ablation and rainwater in the subwatershed of Langtang Valley drain into the river with the runoff coefficient of 1; (2) ablation of the glacier system can be estimated simply using a degree-day factor of 10 mm/degree-day; and (3) precipitation is considered uniform over the whole watershed. Assuming that the suggested phenomena persist throughout the year, records of monthly precipitation and monthly mean temperature in this valley, indicate that annual accumulation and ablation in the glacier system amount to 2000 ± 200 mm, respectively.
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Bajracharya, Sagar Ratna, Narendra Raj Khanal, Pashupati Nepal, Sundar Kumar Rai, Pawan Kumar Ghimire, and Neera Shrestha Pradhan. "Community Assessment of Flood Risks and Early Warning System in Ratu Watershed, Koshi Basin, Nepal." Sustainability 13, no. 6 (March 23, 2021): 3577. http://dx.doi.org/10.3390/su13063577.
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Nepal is highly vulnerable to flood-related disasters which cause considerable loss of lives and property. The vulnerability of communities to flood-related hazards can be reduced by proper planning, preparedness, and responses using various structural and nonstructural measures. The community-based flood early warning system is one such tool that enables local communities to enhance their resilience to flooding risks. This paper highlights the efficacy of the community assessment of flood risks and early warning systems. Using qualitative and quantitative methods, this paper evaluates the progress of a community-based flood early warning system implemented in the Ratu River—a small tributary of the Koshi River. The establishment of a community network in 2015 was instrumental in the dissemination of flood early warning information and in building local capacities to understand the risks and take timely action. The flood early warning resulted in awareness-raising, strengthened upstream–downstream linkages, and resulted in a greater willingness among communities to help each other prepare for flood disasters in the Ratu watershed.
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Bhattarai, Tara Nidhi. "Flood Events in Gangapur Village, Banke District: An Example of Climate Change-induced Disaster in Nepal." Journal of Institute of Science and Technology 19, no. 1 (November 8, 2015): 79–85. http://dx.doi.org/10.3126/jist.v19i1.13832.
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Climate change impacts in Nepal have resulted, among others, localized downpour which may trigger severe flooding and associated disasters in some parts of the country, particularly in the southern slope of the Siwalik. The purpose of this investigation was to evaluate the consequences of climate change impacts in the Dhondra River watershed that covers southern slope of the Siwalik and northern part of the Terai plane in Banke district, western Nepal. For the purpose, a field investigation was carried out and it indicated that Ward Nos. 5 and 6 of Gangapur Village Development Committee (VDC) were inundated in 2000 due to the blockade of the Singhya River by the deposition of flood-driven sediments brought by the Dhondra River. Consequently, about 305 families were completely displaced due to the inundation in and around their home and farmlands. The flood was resulted due to a localized torrential rainfall in Dhondra River's upper reaches in the Siwalik area. Following the year 2000, the Dhondra River started depositing sandy sediments in and around the confluence point with the Singhya River during each monsoon seasons. This paper briefly summarizes the causes of the disaster and its consequences to the displaced people, and surrounding geo-environment.Journal of Institute of Science and Technology, 2014, 19(1): 79-85
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Prajapati, M., and L. Joshi. "Incentive scheme for improving water and watershed management in Bhaktapur, Nepal." Nepal Journal of Environmental Science 2 (December 8, 2014): 51–56. http://dx.doi.org/10.3126/njes.v2i0.22742.
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Fresh water is becoming scarce in many parts of the world. Deteriorating ecosystems, increasing population, changing lifestyles have intensified fresh water scarcity in many urban areas. Using Mahadev Khola watershed as a case, the present study investigates the reasons for decreasing fresh water availability in Bhaktapur municipality. Perceptions of water services among both upstream and downstream communities were collected; data of water supply and time series GIS data of land use change were analyzed. Growth in human population, urbanization, haphazard extraction of water in upstream and downstream areas, pollution of river, and damaged water pipes have led to reduction in fresh water availability in the municipality. Fresh water supply can be improved by implementing a carefully designed integrated water management master plan that incorporates ways to address all the causes of water scarcity. The master plan of Bhaktapur municipality could include an incentive mechanism, such as Payment for Ecosystem Services (PES), in which downstream consumers (municipality population, farmers and industries) provide financial and/or non-financial rewards to the upstream communities for protecting and managing forest ecosystem for water-conserving activities and for not applying hazardous agrochemicals in their fields.
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Bhattarai, Bikas Chandra, and Dhananjay Regmi. "Impact of Climate Change on Water Resources in View of Contribution of Runoff Components in Stream Flow: A Case Study from Langtang Basin, Nepal." Journal of Hydrology and Meteorology 9, no. 1 (August 30, 2016): 74–84. http://dx.doi.org/10.3126/jhm.v9i1.15583.
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Observation and model-based studies suggest substantial hydrological flow pattern changes in mountain watershed where hydrology is dominated by cryospheric processes (IPCC 2007). The response of cryospheric processes to warming climate in mountain areas can be analysed by examining the responses in the seasonal and annual hydrologic regimes of rivers where snowmelt contributes significantly to the runoff. This study is carried out in Langtang basin, which aims to assess the impact of potential warming on snowmelt contribution and river discharge utilizes a Snowmelt Runoff Model (SRM), which is one of a very few models in the world today that requires remote sensing derived snow cover data as a model input. In this study, snow cover and hydrometric data were derived from Moderate Resolution Imaging Spectro-radiometer (MODIS) snow product and Snow and Glacier Hydrological Unit (SGHU) of Department of Hydrology and Meteorology, Government of Nepal. The model is calibrated for the year 2006 and validated in 2005. Different climatic scenarios are used (only change in temperature) to run the model in order to understand the impact of changing climate on runoff component and river discharge. In 2006, snow and glacier melt component contributes 35% in winter, 18% in summer and 19% annually in the stream flow. In this study, model predicts that snow and glacier melt contribution in stream flow will increase approximately at the rate of 2% in winter, 5% in summer and 4% in annual flow per 1°C temperature rise. Due to increase in snowmelt contribution, river discharge will also increase at the rate of 2% in winter, 6% in summer and 5% in annual flow under the projected temperature rise of 1°C.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.74-84
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Rai, Rythum, and Naresh Kazi Tamrakar. "Streambank Erosion Susceptibility Index and Flood-prone Area Mapping along the Karra River, Hetauda, Central Nepal Sub-Himalaya." Transactions on Machine Learning and Artificial Intelligence 7, no. 6 (January 8, 2020): 11–20. http://dx.doi.org/10.14738/tmlai.76.7238.
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The Karra River, one of the major tributaries of the Rapati River, is the 5th order stream that extends for about 21.91 km length in 92 sq. km. of watershed area. It is situated in the southern region of the Hetauda City, which is under the rapid development as a settlement and industrial area. The Karra River area is frequently impacted by streambank erosion and flooding during the heavy rainfall in monsoon due to loosely consolidated sedimentary terrain of the Upper Siwalik Subgroup and the unconsolidated Late Quaternary Deposits, which are vulnerable to erosion. Morpho-hydraulic parameters and stream cross-sectional characteristics and parameters of streambank erosion susceptibility index (SESI) rating system were assessed along the Karra River at 19 transects. The rating of the SESI are based on bank angle, bank height ratio, root depth ratio, root density, surface protection, bank materials and characteristics of stratification. The flood-prone area map was prepared based on the morpho-hydraulic parameters of the stream based on the maximum bankfull depth. The ER and W/D ratio were estimated to determine the affinity of flooding and lateral instability of the stream. Near Bank Stress Index and SESI dealt with streambank erosion potential were assessed to estimate the streambank erosion rate.
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Tamrakar, Naresh Kazi, Ramita Bajracharya, Sudarshon Sapkota, Ishwar Thapa, Prem Paudel, and Niraj Bal Tamang. "Riverbank erosion potential and channel stability status of the Kodku River, southern Kathmandu Basin, Central Nepal." Bulletin of the Department of Geology 17 (June 8, 2015): 1–41. http://dx.doi.org/10.3126/bdg.v17i0.12723.
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The Kodku River is a southern tributary of the Manahara River and extends for about 15.86 km with 35.67 sq. km of watershed area. It is quite a potential linkage between the hilly, southern Kathmandu and the urban, inner Kathmandu. The river corridors are frequently subject to bank erosion, slope movements and flash flooding. Riverbank erosion is an important cause of toe erosion of slopes causing landslides and also posing threat on the infrastructures. Stream channel stability is crucial to understand overall river stability. Recognition of existing stability condition of river is to understand nature and behavior of the river, and is important in many ways: (a) to recognize the bank erosion and lateral instability hazard, (b) to develop infrastructure along or nearby the river corridor, (c) to start on where to restore the river, (d) to develop reservoir and exploit natural resources, and (e) to develop safe settlement areas. The Kodku River is a gravelly mixed-load meandering river. Level II classification distinguishes the Badikhel Segment as a ‘B4c’ type stream, the Taukhel Segment as a ‘C6c’ type, and the fifth order segments such as the Arubot, Thaiba and Harisidhi Segments as ‘C4c’ type streams. The ‘B4c’ type stream is entrenched and somewhat laterally confined by steep valley slopes and terrace landforms. It has the highest unit stream power (16.64 Nm/ s/m2), high potential of bed material scouring and tendency of vertical instability. The ‘C6c’ type stream is a meandering stream with shallow channel and wide valley. The ‘C4c’ type streams have shallow and wide meandering channels with well developed flood plains and lateral bars, and have the least unit stream power (in Harishiddi Segment 0.11N-m/s/m2), low potential of river bed material erosion but have tendency of lateral instabilities. The bank erosion hazard map indicates that the upper third order stretch and few downstream stretches lie in low hazard zone, but the overall areas of the Harisidhi Segment, Gwarko, Imadol and some other areas lie in high to very high hazard zone because of devegetation, modification of channels and other anthropogenic activities in addition to the weak nature of the bank materials.DOI: http://dx.doi.org/10.3126/bdg.v17i0.12723Bulletin of the Department of Geology, Vol. 17, 2014, pp. 1-41
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Kayastha, Nagendra, Umesh Singh, and Krishna Prasad Dulal. "A GIS Approach for Rapid Identification of Run-of-River (RoR) Hydropower Potential Site in Watershed: A case study of Bhote Koshi Watershed, Nepal." Hydro Nepal: Journal of Water, Energy and Environment 23 (August 21, 2018): 48–55. http://dx.doi.org/10.3126/hn.v23i0.20825.
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A new Geographical Information System (GIS) approach is proposed to assess primary potential hydropower site, explicitly identifying highly possible hydropower locations spatially, over a large area in a short time. The results from this approach were validated with an existing hydropower site in the Bhote Koshi catchment in Nepal. Altogether 885 number of searches made along the river streams each covered a circular area of radius 10 km, with distance between headwork and power houses of 500 m intervals, thus, identified 297 highly potential sites out of total 2655 during evaluation. The results indicate that, 52 sub-catchments have potential areas and seven specific hydropower locations overlapped with existing hydropower projects. This approach is suitable for initial screening only and the produced results significantly facilitate further in-depth feasibility study to engineering and economic analysis for hydropower potential of the basin. HYDRO Nepal JournalJournal of Water, Energy and Environment Issue: 23Year: 2018
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Shrestha, U. S. "Land Use and Land Cover Classification from ETM Sensor Data : A Case Study from Tamakoshi River Basin of Nepal." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (November 28, 2014): 943–48. http://dx.doi.org/10.5194/isprsarchives-xl-8-943-2014.
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The mountain watershed of Nepal is highly rugged, inaccessible and difficult for acquiring field data. The application of ETM sensor Data Sat satellite image of 30 meter pixel resolutions has been used for land use and land cover classification of Tamakoshi River Basin (TRB) of Nepal. The paper tries to examine the strength of image classification methods in derivation of land use and land classification. Supervised digital image classification techniques was used for examination the thematic classification. Field verification, Google earth image, aerial photographs, topographical sheet and GPS locations were used for land use and land cover type classification, selecting training samples and assessing accuracy of classification results. Six major land use and land cover types: forest land, water bodies, bush/grass land, barren land, snow land and agricultural land was extracted using the method. Moreover, there is spatial variation of statistics of classified land uses and land cover types depending upon the classification methods. <br><br> The image data revealed that the major portion of the surface area is covered by unclassified bush and grass land covering 34.62 per cent followed by barren land (28 per cent). The knowledge derived from supervised classification was applied for the study. The result based on the field survey of the area during July 2014 also verifies the same result. So image classification is found more reliable in land use and land cover classification of mountain watershed of Nepal.
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Tamrakar, Naresh Kazi, and Binod Karki. "Geomorphometric properties and variability of sediment delivery ratio and specific sediment yield among sub-basins of the Karra River, Hetauda, central Nepal Sub-Himalaya." Journal of Nepal Geological Society 59 (July 24, 2019): 19–37. http://dx.doi.org/10.3126/jngs.v59i0.24983.
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Geomorphometric properties of watershed-scale are often calculated to characterize drainage basins morphology for evaluating their geomorphic status of basin development. More recently these properties have widely been applied in inferring the sediment delivery ratio and sediment yields of the basin to estimate and know sediment erosion status of drainage basin with the help of morph metric data. In fact, sediment delivery ratio (SDR) and specific sediment yield (SSY) of the basins depend not only on watershed properties but also indirectly on other factors such as climate, hydrology, land use and geology, which can be of low variation for a small watershed. The aims of the present study were to compute some of the geomorphometric parameters of the Karra River Basin (KRB), located in Hetauda, Makawanpur District, Central Nepal, to compare some of these among the sub-basins with varying geology, touse some of parameters in estimating sub-basin-wide SDR and SSY using empirical equations and to infer geomorphic development and erosion status of the basin. Based on hypsometric analysis, the southern sub-basins with mainly gravelly terrain are mostly of mature to unstable phase, whereas the northern sub-basins with bedrocks of the Lower and the Middle Siwalik Subgroups are of Monadnock phase to mature stage of basin development. Sediment delivery ratio (SDR) and specific sediment yield (SSY) estimated for the southern sub-basins of the KRB are relatively lower compared to those estimated for the northern sub-basins. Considering the geology of the KRB and hypsometric integral, although the SDR and SSY of the southern sub-basins are lower compared to the northern sub-basins, the southern sub-basins are vulnerable to erosion because of their unstable geomorphic development stage and pervasive distribution of unconsolidated weak sediments having high erodibility.
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Bhandari, Bharat Prasad, and Subodh Dhakal. "Decadal Evolution of Landslides in the Siwalik Zone: a Case Study of Babai Watershed, Nepal." Journal of Institute of Science and Technology 26, no. 1 (June 18, 2021): 57–62. http://dx.doi.org/10.3126/jist.v26i1.37864.
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The Siwalik zone of the Nepal Himalaya is highly sensitive to landslides. The study of landslides in the catchment scale gives the basic concept of the overall landslides of the typical zone. In this study, the decadal evolution trend of the four largest landslides of the Babai River watershed was evaluated. The Landsat, Sentinel-2, and Google Earth imageries were used to obtain the physical data of the landslide from 2010 to 2019. The area, total length, and width of scar toe, and the body of landslides were obtained from the images. The rainfall data of two stations was used to evaluate the role of rainfall in the landslide development and evolution process. The trend of rainfall and area of landslides was not the same but the development process of all four landslides was more or less similar. The area of landslides fluctuated till 2014 but suddenly increased after 2015. The landslide area was highest in 2017 and moderately changed in 2018 and 2019. The landslides showed dynamic behavior in a decade with their typical expanding, widening, and reducing characters.
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Khanna, Sabita Aryal, Kundan Lal Shrestha, Ramesh Kumar Maskey, Alaka Lamsal, Keshab Pyakurel, Manisha Poudyal, Manish Ranjit, Drishtant Karki, Ranjan Aryal, and Ashish Shrestha. "Integrated Water Resource Management (IWRM): A Case Study of Durlung Watershed, Bagmati Zone, Nepal." Hydro Nepal: Journal of Water, Energy and Environment 18 (March 15, 2016): 47–54. http://dx.doi.org/10.3126/hn.v18i0.14645.
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Water in Nepal is a key strategic natural resource, which has the potential to lead the all round development and economic growth of the country. Integrated Water Resource Management (IWRM) is a holistic management approach, integrating land water interaction, socio economic groups, upstream downstream relations, indigenous knowledge, and institutions built up, along the temporal dimensions based on an agreed set of principles. It is a bottom-up decentralized approach for the management of water resources. IWRM is a challenge to conventional practices, attitudes and professional certainties. It confronts entrenched sectoral interest & requires that the water resources are managed holistically for the benefits of all.The broad objective of the multidisciplinary study was to assess the possibilities of Human Dimensions of water resource development and its management. Water resource accounting is done by the collection of water resources data through participatory group formation. Scientific data of hydro and metrological stations was also acquired. Hydrological modeling tools were also used. Feasibility of hydropower plant and potential of power production in the basin was readily estimated.Total daily discharge of the Durlung Watershed was estimated on an average of 157 Million Liters. Rivers of the watershed are turbulent, unsteady & flowing with very high current, which can be utilized by local people for low cost drinking water, tourism, irrigation & hydropower generation. Micro-hydropower production possibilities in Ratan and Deuta rivers have shown multidimensional positive impacts on socio-economic development of the region. Level of community partnership in IWRM and synchronization with the local, district & national level institutional framework for Basin Management was observed to be satisfactory. Participatory research was carried to identify water resource base with school & community partnership. Community motives, their difficulties and gaps in community level organization were identified. For capabilities of community to take over the responsibilities of IWRM concept, there is a lot more need of training and capacity building for now. HYDRO Nepal Journal of Water Energy and EnvironmentVolume- 18, 2016, JanuaryPage -47 to 54
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Karki, Swarup Singh, and Naresh Kazi Tamrakar. "Fluvial morphology and dynamics of the Godavari Khola, southeast Kathmandu, Central Nepal." Bulletin of the Department of Geology 19 (December 1, 2016): 15–28. http://dx.doi.org/10.3126/bdg.v19i0.19990.
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The Godavari Khola flowing from the south to the north contributes the Hanumante Khola, which is one of important tributaries of the Bagmati River, flowing from the eastern part of the Kathmandu Basin. Recently, the Godavari Khola has been suffering from human encroachments due to rapid urbanization. Studying nature and dynamics of the stream are important works if the stream has to be made less affected and well managed. The present study aims to establish fluvial morphology and stability status of the Godavari Khola. For these purposes, the watershed was analysed for morphometric parameters and planform fluvial morphology, and thirteen representative segments were surveyed from upstream to downstream of the Godavari Khola for recording and analysing sediment properties, stream cross-sections and profiles, and hydraulic parameters, river dynamics and stability.The Godavari River is a fifth order stream, the two upstream segments of which are bedrock channels, and the rest of the segments are alluvial channels. The segments are classified into six kinds such as C4-, C5-, B3-, B4-, E4- and F4-type streams. The upstream segments are of B4-, B3- and ‘F4’-types which show entrenched, steep, gravel to cobble grade streams. The downstream segments are of C4-, C5-, E4- and F4-types showing non-entrenched to low entrenched streams with gentle slopes, high sinuosity and gravel to sand grade bed materials. The stability status of the Godavari Khola shows that the stream segments 1, 2, 11 and 13 lie in the degrading condition whereas the remaining nine segments lie in the aggrading condition. Because of the huge width/depth ratio in majority of the downstream channels, bank erosion is relatively prone in the downstream segments of the Godavari Khola, whereas bed incision is prone in segments 11 and 13.Bulletin of the Department of Geology, Vol. 19, 2016, pp. 15–28
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Lamichhane and Shakya. "Integrated Assessment of Climate Change and Land Use Change Impacts on Hydrology in the Kathmandu Valley Watershed, Central Nepal." Water 11, no. 10 (October 2, 2019): 2059. http://dx.doi.org/10.3390/w11102059.
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The population growth and urbanization are rapidly increasing in both central and peripheral areas of the Kathmandu Valley (KV) watershed. Land use/cover (LULC) change and climate variability/change are exacerbating the hydrological cycle in the KV. This study aims to evaluate the extent of changes in hydrology due to changes in climate, LULC and integrated change considering both factors, with KV watershed in central Nepal as a case study. Historical LULC data were extracted from satellite image and future LULC are projected in decadal scale (2020 to 2050) using CLUE-S (the Conversion of Land Use and its Effects at Small regional contest) model. Future climate is projected based on three regional climate models (RCMs) and two representative concentration pathways (RCPs) scenarios, namely, RCP4.5 and RCP8.5. A hydrological model in soil and water assessment tool (SWAT) was developed to simulate hydrology and analyze impacts in hydrology under various scenarios. The modeling results show that the river runoff for RCP4.5 scenarios is projected to increase by 37%, 21%, and 12%, respectively, for climate change only, LULC only, and integrated changes of both. LULC change resulted in an increase in average annual flow, however, a decrease in base-flow. Furthermore, the impacts of integrated changes in both LULC and climate is not a simple superposition of individual changes.
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Singh, Achyut Man. "An Environmentally Friendly Integrated Development Approach for Nepal (Experiences from Irrigation Sector Projects)." Hydro Nepal: Journal of Water, Energy and Environment 20 (January 27, 2017): 31–40. http://dx.doi.org/10.3126/hn.v20i0.16486.
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Nepal has distinctly three ecological regions: (i) high mountain, (ii) mid-hills, and (iii) terai with their varying climatic and physiographic features. The experiences gathered from Irrigation Sector Projects implemented under various donor agencies such as the World Bank (WB), Asian Development Bank (ADB), and UN/ILO have shown that successful irrigation projects must be defined and planned according to specific ecological regions and pertinent to the local environment. An integrated development approach considers the land use, roads, market, and other economic activities as they relate to prospects for poverty alleviation. Land evaluation and subsequent land use planning according to the soil, climate, land profile, and suitability of agriculture practices should be considered in the development works to ensure true benefit to the rural populations. The integrated approach as such will provide long term sustainability through environmentally sound practices. This approach has been widely applied in the European countries, Korea, Japan, and Sri Lanka.This paper primarily focuses on the irrigation and development approaches most suitable to Nepal’s three ecological regions. High mountain regions should be developed with pasture land, horticulture, organic vegetable farming, and tourism. Irrigation technology in these areas should be simple pipe conveyance, and tank irrigation. In the mid-hills horticulture on the sloping terrain and cereal crops in the river valleys with other diversified cropping systems should be applied. The Terai region is the ‘Bread Basket’ of Nepal, and has high potential for diversified agriculture and industrial development.For development in these regions to succeed, road networks and transportation facilities are essential to economic growth. Road transportation maximizes opportunity for tourism and other economic activities. Development work must be planned in an integrated approach, which should be based on appropriate land use patterns for environmentally sustainable practices. An ideal solution would be to envision the watershed as the unit for eco-friendly sustainable development planning involving all the stakeholders under the watershed purview. As an example, the principles of Integrated Water Resources Management Planning (IWRMP), and Integrated Watershed Management Plan (IWMP) have been successfully applied in the USA and Australia (Box 1). It has illustrated that vegetative covered catchment stores large amount of rain water, increases groundwater table, reduces erosion of soil, and lastly decreases the intensity of flood hazard. Whereas, the naked catchment areas are highly erodible, does not store rain water, susceptible to high erosion and landslides, and increases the flood intensity by three fold than a vegetative covered one. The vegetative cover increases the water resources availability for over all development for agriculture. HYDRO Nepal JournalJournal of Water Energy and EnvironmentIssue: 20Page: 31-40
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Pathak, Mahesh. "Application of GIS and Remote Sensing for Hydropower Development in Nepal." Hydro Nepal: Journal of Water, Energy and Environment 3 (May 26, 2009): 42–45. http://dx.doi.org/10.3126/hn.v3i0.1920.
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Nepal is endowed with abundant water resources from the availability point of view. Hydropower is considered as a viable means of economic growth for the country's overall development. The river and physiographic characteristics of Nepal offer immense possibilities for the development of hydropower schemes of different scales, and various national and international agencies have expressed keen interest. On the other hand, Nepal's biodiversity resources, a fragile landscape, scattered settlement patterns and natural resource based rural livelihoods are directly affected by hydropower development. Use of recent information about place, people and scientific analysis is crucial for addressing the environmental and socio-economic impacts of development activities. Geographic Information System (GIS) and Remote Sensing (RS) technology have the capabilities to create, update and manage recent information about the earth's surface and its integration with socio- economic information; but these technologies have not been used properly for the hydropower development sector in Nepal. This paper is about the application of GIS and Remote sensing technology to make the hydropower development environment friendly and to create less impact upon the rural livelihood. Key words: GIS, Remote Sensing, hydropower, watershed management, Nepal doi: 10.3126/hn.v3i0.1920 Hydro Nepal Journal of Water, Energy and Environment Issue No. 3, July 2008. Page: 42-45
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Basnet, P., M. K. Balla, and B. M. Pradhan. "Landslide hazard zonation, mapping and investigation of triggering factors in Phewa lake watershed, Nepal." Banko Janakari 22, no. 2 (December 1, 2013): 43–52. http://dx.doi.org/10.3126/banko.v22i2.9198.
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The landslide triggering factors were investigated followed by the thematic maps and landslide distribution map prepared and classified using the GPS and GIS Softwares like CartaLinx, ArcView and ERDAS IMAGINE in Sarangkot and Kaskikot Village Development Committees, Kaski district. In analytical hierarchy process, the factors for zonation were compared by Couple Comparison Method and their weights were determined using Arithmetic Mean Method and earned weight values of each factor. The landslide hazard zonation model was employed to prepare landslide hazard zonation map of the study area, and then classified into five relative hazard classes using the equal interval classification method. Finally, the landslide hazard zonation map was crossed with the landslide distribution map and the model applicability was confirmed by determining the per hazard class percent of area covered by the landslide. In the land hazard zonation map, 0.44% of the study area was in very low hazard, 2.11% in low hazard, 54.92% in moderate hazard, 21.34% in high hazard and 21.19% in very high hazard area. The major portion of the study area was on the moderate zone whereas the least portion was on the very low hazard zone. In the study area, most of the high and very high hazard class areas were found occupying the areas closer to the linear triggering factors like presence of linement and fault, presence of motorable road and presence of rivers and streams. The landslide density of the study area was found to be 0.44 per km2 indicating the higher hazard susceptibility of the area.DOI: http://dx.doi.org/10.3126/banko.v22i2.9198Banko Janakari: A Journal of Forestry Information for NepalVol. 22, No. 2, 2012 November Page: 43-52 Uploaded date: 12/1/2013
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Bhandari, Bharat Prasad, and Subodh Dhakal. "Compositional analysis and phase relations of soil mass from the active landslides of Babai River watershed, Siwalik zone of Nepal." Engineering Geology 278 (December 2020): 105851. http://dx.doi.org/10.1016/j.enggeo.2020.105851.
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Emerman, Steven H., Janae R. Nelson, J. Kade Carlson, Tracy K. Anderson, Anusha Sharma, and Basanta R. Adhikari. "The effect of surface lithology on arsenic and other heavy metals in surface water and groundwater in Mustang Valley, Nepal Himalaya." Journal of Nepal Geological Society 47, no. 1 (June 30, 2014): 1–21. http://dx.doi.org/10.3126/jngs.v47i1.23100.
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Recent studies have shown that elevated groundwater as occurs even in Kathmandu and Pokhara Valleys in Nepal, two tectonic valleys well upstream of the floodplain of the Ganges River. Moreover, studies in both valleys showed surface water As to be statistically indistinguishable from groundwater As, which led to the fluvial recharge model in which elevated groundwater As results from losing streams with elevated As, which is a consequence of rapid erosion caused by a combination of monsoon climate, tectonic uplift and deforestation. The objective of this study was to further test the fluvial recharge model in Mustang Valley, the third major tectonic valley in Nepal Himalaya far upstream from the floodplain of the Ganges River. In May 2011 water samples were collected from 33 surface water sites (24 directly from streams and 9 from canals, pipes or taps fed by streams) and 24 groundwater sites (10 directly from springs and 14 from pipes or taps fed by springs). The WHO As Standard was exceeded in 47% of surface water samples and 79% of groundwater samples, including all nine functioning water taps in Lo-Manthang, the largest village. Separating samples into a high- As Region I (geometric mean As = 0.071 mg/L) and a low-As Region II (undetectable As for 85% of samples) showed that surface water As and groundwater As were statistically indistinguishable within each region. Only Region I receives overland flow from the exposed Mustang and Mugu Granites. The correspondence between groundwater As and watershed surface lithology is further evidence for the fluvial recharge model.
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Gurung, Pabitra, Luna Bharati, and Saroj Karki. "Impact of climate change and watershed interventions on water balance and crop yield in West Seti river sub-basin of Nepal." Journal of Hill Agriculture 6, no. 2 (2015): 219. http://dx.doi.org/10.5958/2230-7338.2015.00051.8.
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Dhital, Megh Raj. "Impact of July 2004 high-intensity rain on Hilepani-Jayaramghat-Diktel Environment-Friendly Road in East Nepal." Journal of Nepal Geological Society 34 (October 9, 2006): 81–94. http://dx.doi.org/10.3126/jngs.v34i0.31882.
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The high-intensity rain of 5-13 July 2004 activated numerous landslides, gullies, and debris flows in the watershed of the Dudh Koshi River in east Nepal. As a result, the Hilepani- Jayaramghat- Diktel Environment-Friendly Road was devastated. Apart from the rainfall, geological, geomorphic, land use, and road construction practices were other important factors leading to the disaster. Most of the damage was concentrated on concave slopes, whereas the ridges and convex slopes were relatively safe. The entire alignment was devoid of any breast or retaining walls necessary to protect the high, steep, and bare soil cut slopes, and it resulted in extensive cut slope failures. Similarly, side and cross drains were almost nonexistent. As a result, severe damage was seen at almost every gully crossing. There were very few gully protection structures (viz. check dams) and, like the retaining walls constructed below the road, they also suffered from poor construction quality and failed due to weak foundation and inadequate keying practices. Some of the most awkward structures were the loops founded on unstable slopes with high (up to 15 m) and robust gabion walls at the bends, and deep box cuts above them. In these circumstances, the concentrated runoff and subsequent debris flow from the box cut devastated the entire hairpin bend.
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Devkota, Dinesh Chandra, Kamal Thapa, and Bhaskar Kharki. "Economic analysis of ecosystem based adaptation and engineering options: A case study from Udayapur, Nepal." Nepal Journal of Environmental Science 3 (December 7, 2015): 35–42. http://dx.doi.org/10.3126/njes.v3i0.22733.
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Ecosystem services are vital to our well-being as they directly or indirectly support our survival and quality of life. But, the growing impact of climate change diminishes the benefit from ecosystem services. Therefore, identifying possible applicable adaptation options are inevitable to reduce the effect of climate change. The present research is based on a case study of Ksedi River watershed, Ajgada Village in Udaypur district of Nepal. The study demonstrates the comparison between different options to deal with flood and make a sound decision, based on economic rationale for long-term benefits. The present study compares ecosystem based adaptation options with engineering options using cost benefit analysis in order to protect village from flooding. Through stakeholder and expert consultations, ecosystem based adaptation options and economic options that are feasible in the village and catchment to mitigate the floods were listed. Economic analysis of these options and the different combinations were done using cost benefit analysis. Analysis was carried out for each of the different combination of options. Focus on ecosystem based adaptation options provide high benefit to cost return in terms of avoided damages and considering engineering options efficient in flood and erosion control in initial stage in spite of its high cost. The study suggests that reforestation in upland forest areas; plantation along riverbed and management of rangeland should be prioritized. Similarly, preparation of flood model, flood height damage curve and flood vulnerable maps specific to the site will help decision makers to implement site specific adaptation options.
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Maharjan, Manisha, Anil Aryal, Rocky Talchabhadel, and Bhesh Raj Thapa. "Impact of Climate Change on the Streamflow Modulated by Changes in Precipitation and Temperature in the North Latitude Watershed of Nepal." Hydrology 8, no. 3 (August 6, 2021): 117. http://dx.doi.org/10.3390/hydrology8030117.
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It is unambiguous that climate change alters the intensity and frequency of precipitation and temperature distribution at the global and local levels. The rate of change in temperature in the northern latitudes is higher than the worldwide average. The annual distribution of precipitation over the Himalayas in the northern latitudes shows substantial spatial and temporal heterogeneity. Precipitation and temperature are the major driving factors that impact the streamflow and water availability in the basin, illustrating the importance of research on the impact of climate change on streamflow by varying the precipitation and temperature in the Thuli Bheri River Basin (TBRB). Multiple climate models were used to project and evaluate the precipitation and temperature distribution changes in temporal and spatial domains. To analyze the potential impact of climate change on the streamflow in the basin, the Soil and Water Assessment Tool (SWAT) hydrological model was used. The climate projection was carried out in three future time windows. The result shows that the precipitation fluctuates between approximately +12% and +50%, the maximum temperature varies between −7% and +7%, and the minimum temperature rises from +0.7% to +5% in intermediate- and high-emission scenarios. In contrast, the streamflow in the basin varies from −40% to +85%. Thus, there is a significant trend in the temperature increase and precipitation reduction in the basin. Further, the relationship between precipitation and temperature with streamflow shows a substantial dependency between them. The variability in precipitation and streamflow is successfully represented by the water yield in the basin, which plays an important role in the sustainability of the water-related projects in the basin and downstream to it. This also helps quantify the amount of water available for hydropower generation, agricultural production, and the water ecosystem in the TBRB.
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Gyawali, Prakash, and Naresh Kazi Tamrakar. "Landslide susceptibility assessment of the Chure Khola Catchment area of the Siwalik region, Central Nepal." Journal of Nepal Geological Society 56, no. 1 (June 28, 2018): 19–30. http://dx.doi.org/10.3126/jngs.v56i1.22696.
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Landslide susceptibility analysis is carried out in the Chure Khola Catchment, between Amlekhganj and the Churia Mai Range of the Bara District, covering area of 20 sq. km. The catchment lies in the Siwalik Hills composing the Siwalik Group of rocks of Middle Miocene to Early Pleistocene age. Owing to the week and fragile geology, the Siwalik Hills are prone to the gully erosion, shallow landslide and debris flow, during the heavy rain storms in monsoon seasons. In the present study, landslide susceptibility assessment was carried out using two methods, rapid field-based assessment and statistical index methods. For the susceptibility mapping of the river bank slopes, field- based method was used. The seven parameters such as slope angle, slope material, reduction to groundwater, effect of drainage, effect of past failure, effect of vegetation cover and effect of land use were used to calculate the factor of safety in the field. The slope areas were classified as highly susceptible (FS<0.7), susceptible (0.7<FS<1), marginally stable (1<FS<1.2) and stable (FS>1.2) categories, and finally, a susceptibility map was prepared. For the total 4.179 sq. km area where rapid field-based assessment was carried out, the areas covered by highly susceptible, susceptible, marginally stable and stable zones are respectively, 21.56%, 22.11%, 17.37% and 38.95%. Among the highly susceptible and susceptible zones identified, 71% sites have experienced recent slope failures. Landslide susceptibility mapping of the whole catchment area was prepared using statistical index method, and considering seven causative parameters such as elevation, slope, slope aspect, curvature, river proximity, stream density and lithology, which were determined and prepared from DEM using Arc GIS. Eighty percent landslides were used as the training sample for the spatial analysis, whereas 20% landslides were used for the validation of the study. The landslide susceptibility map exhibits the areas covered by very high, high, moderate, low and very low susceptibility zones are 47.18%, 25.28%, 19.77%, 3.60% and 4.16%, respectively. Validity of the study was determined using Riemann Sums method. Success Rate Curve shows that 78.04 % of the areas lie under the curve. Evaluating susceptibility in small watershed is important to mitigate shallow landslide related problems and in rehabilitating forest areas in the Churiya Hills of Nepal.
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Kim, Dong Eun, Yeong Bae Seong, Kwang Hee Choi, and Byung Yong Yu. "Role of debris flow on the change of 10Be concentration in rapidly eroding watersheds: a case study on the Seti River, central Nepal." Journal of Mountain Science 14, no. 4 (March 30, 2017): 716–30. http://dx.doi.org/10.1007/s11629-016-4282-y.
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Bhatta, Binod, Sangam Shrestha, Pallav K. Shrestha, and Rocky Talchabhadel. "Modelling the impact of past and future climate scenarios on streamflow in a highly mountainous watershed: A case study in the West Seti River Basin, Nepal." Science of The Total Environment 740 (October 2020): 140156. http://dx.doi.org/10.1016/j.scitotenv.2020.140156.
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Higaki, Daisuke. "Erosion and sedimentation problems in Nepal from the viewpoint of morphological development." Journal of Nepal Geological Society 18 (December 1, 1998). http://dx.doi.org/10.3126/jngs.v18i0.32265.
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Three cases of disasters such as landslides, debris flows and unstable river courses are presented from the viewpoint of morphological development in Nepal. In the Tukuche village in the Higher Himalaya, shallow landslides occur in moraine deposits covered with recent fluvial deposits promoting bank erosion of the Kali Gandaki River. The slope towards the river bank composed of Quaternary glacial deposits should be noticed as landslide-prone areas in this region.
Alluvial fans are less developed and widths of river courses are larger on the rivers originating from the Upper Siwaliks than those from the Middle/Lower Siwaliks in the eastern Churia hills. Because material size produced from hill slopes is smaller in the former case than the latter case, less tractive force by river stream can transport river bed materials and erode river banks. Consequently, the river topography is altered dramatically. River course control works are very important for the former case.
Countermeasures for the torrents affected by debris flows in 1981 are also discussed in this paper. Distribution and volume of unstable deposits depend on the stage of morphological development of a torrent watershed. Analysis of morphological development was carried out on the basis of mapping and volume estimation of unstable deposits on the slopes and valley floors in two torrent watersheds of the Nallu Khola in the Mahabarat Range.
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Shrestha, Pramila, and Naresh Kazi Tamrakar. "Morphometry and geomorphic development of the Bagmati River Basin, Nepal Himalaya." Journal of Nepal Geological Society 46 (December 2, 2013). http://dx.doi.org/10.3126/jngs.v46i0.31582.
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Morphometric analysis of a watershed provides a quantitative description of the drainage system which is an important aspect of characterization of watershed. The analysis requires measurement of linear features, aerial aspects, gradient of channel network and contributing ground slopes of the drainage basin. The morphometric characteristics at the watershed-scale may contain important information regarding its formation and development because all hydrologic and geomorphic processes occur within the watershed. In this study morphometric property of the Bagmati River Basin (BRB) was investigated using different morphometric attributes and hypsometric analysis in order to investigate geomorphic development of the river basin, in an active tectonic zone. DEM has been prepared from the contour and spot height data using digital topographic maps of 1:25000-scale acquired from the Department of Survey, Nepal. The main stem Bagmati River is the eighth order perennial river that stretches for 206 km with an elongated catchment of area 3761 sq. km. It consists of 39 sub-basins of fourth order and higher. The study shows that the drainage system of the BRB is attaining a mature stage from a youth stage from lower order streams to the higher order streams in geomorphic development process. Some exceptions occurred at higher order stream segments, where drainage development seems to control by structure and lithology. According to the analytical results, erosional stage and level of tectonic activity of sub-basins differ from each other. Generally, the lithology and geological structure seems to control the drainage texture and relief of the BRB. The river system within the Kathmandu Valley is attaining maturity having meandering channels with wide flood plains, whereas rivers of the Lesser Himalaya and the Siwaliks are at youth stage with erosional potential. The downstream part of higher order stream segments are in mature stage having potential for lateral erosion and meander migration. Therefore, the Bagmati River stretch, especially the eight order one poses vulnerability to bank erosion.
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Thapa, Bhumika, Ramesh Raj Pant, Sudeep Thakuri, and Gregory Pond. "Assessment of spring water quality in Jhimruk River Watershed, Lesser Himalaya, Nepal." Environmental Earth Sciences 79, no. 22 (October 31, 2020). http://dx.doi.org/10.1007/s12665-020-09252-4.
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Adhikari, Sanot, Anup Gurung, Raju Chauhan, Deepak Rijal, Bhawani S. Dongol, Dibit Aryal, and Rocky Talchabhadel. "Status of springs in mountain watershed of western Nepal." Water Policy, December 8, 2020. http://dx.doi.org/10.2166/wp.2020.187.
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Abstract The study, conducted in western hilly areas of Nepal, inventoried and mapped over 4,222 springs from five different watersheds. The study showed that more than 50% of the spring sources were found under natural conditions, i.e., open spring whereas 15% of them were of pond type. Similarly, the other 15% spring was recorded as a concrete structure or tank while 1% was determined to be a well. Attempts were made to identify if a change in water discharge from springs relates to rainfall patterns. The inter-annual variability analysis shows a significant fluctuation suggesting variation in water discharge across spring sources. The lowest amount of yearly rainfall received in the river basin is governed by decreasing water flow from the springs in the upper and mid-hills of Nepal. Besides, the intra-annual variation (i.e., seasonal and concentrative nature of rainfall only during monsoon) leads to shortage of drinking water and other domestic purposes (e.g., cooking, cleaning) during the dry months of the year. This study, based on the estimation of discharge flow in these springs, revealed that about 70% were decreasing and, in particular, the flow over the recent ten years decreased significantly.
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Higaki, D., H. Yagi, K. Asahi, and N. Miyake. "Landslides on the late Quaternary deposits in the Bhote Koshi area, central Nepal." Journal of Nepal Geological Society 22 (December 1, 2000). http://dx.doi.org/10.3126/jngs.v22i0.32424.
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ABSTRACT
The origin and age of piedmont talus slopes and their relationship with present landslides are studied in the Bhote Koshi area of central Nepal. The talus slopes near Lamosanghu consist of 7-15 m thick boulder-rich colluvium overlying the Middle terrace deposits of the Sun Koshi River. The organic debris within these layers was dated 12,745±160 years BP (Nu-967) and 12,970±100 years BP (Beta-130478).The pollen analysis of the sediments revealed that a cool temperate to subalpine conifer forests existed in the adjacent area, and marshland was formed near the Sun Koshi River. According to the limited distribution of glacial landforms above 4.000 m in the upper Bhote Koshi watershed, the upper talus slope deposits had not originated from glaciation, but from frequent landslides on the higher slopes 12,000- 13,000 years ago, presumably during the latest Last Glacial time and the early Holocene.
The talus deposits were formed by block sliding on the alternating bands of phyllite and quartzite. On the other hand, near the Main Central Thrust, abundant groundwater is available to trigger present frequent landslides on the talus slopes.
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Thapa, P. B., and M. R. Dhital. "Landslides and debris flows of 19-21 July 1993 in the Agra Khola watershed of Central Nepal." Journal of Nepal Geological Society 21 (July 1, 2000). http://dx.doi.org/10.3126/jngs.v21i0.32143.
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High intensity rainfall of 19-21 July 1993 triggered off a large number of mass movements in the Agra Khola watershed of Central Nepal. It caused a heavy loss of human lives and property. Landslides were distributed mainly in the upper part of the watershed, especially in the vicinity of Chisapani, Chaubas, Dandabas, and Chhap. Main types of mass movement were rockslides, soils slides, and complex failures. About 51% of them were soil slides and 18% were rockslides. Among the rockslides, 4% were deep-seated rotational slides. Large deep-seated rockslides were common on the north-facing dip slopes, whereas shallow slides were observed on the counter dip slopes and in the area occupied by granite. Soil slides occurred on slopes covered by 1-6 m deep colluvium and/or residual soils. The highest percentage of landslides was found in the Kulikhani Formation and on slopes of 25°-45°. The material from landslides contributed to a huge amount of debris, which was deposited on cultivated land. The debris formed up to 5 m high terraces along the rivers. The upper reaches of the Agra Khola and Chalti Khola are the main hazardous areas.
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Yigez, Belayneh, Donghong Xiong, Baojun Zhang, Yong Yuan, Muhammad Aslam Baig, Nirmal Mani Dahal, Awoke Guadie, Wei Zhao, and Yanhong Wu. "Spatial distribution of soil erosion and sediment yield in the Koshi River Basin, Nepal: a case study of Triyuga watershed." Journal of Soils and Sediments, August 9, 2021. http://dx.doi.org/10.1007/s11368-021-03023-9.
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