Bulletin of The Department of Geology最新文献

{"title":"Dry season discharge and sediment yield of the northern tributaries of the Kathmandu Valley, Central Nepal","authors":"Rajkumar Lama, N. Tamrakar","doi":"10.3126/BDG.V19I0.19988","DOIUrl":"https://doi.org/10.3126/BDG.V19I0.19988","url":null,"abstract":"Population growth, urbanization and improper land use practice cause change in natural behavior of the river system. In this point soil erosion and sediment deposition in the river channel adversely bring environmental problems like variation in discharge, surface water physical quality, sediment transportation capacity, sediment yield and stream power. In lack of proper research and planning, disasters like flooding, failure of engineering structure, bank erosion and imbalance in aquatic ecosystem can be seen. To better understand the stream, present work was carried out to determine the discharge, sediment transportation capacity, sediments yield and stream power of northern major tributaries of the Bagmati River. Subsequent to this, relations between the two or more than two morpho-hydraulic parameters with the discharge and sediments load were evaluated.The northern Bagmati River basin occupies an area of 3750 sq. km and lies within 26°42’ and 27°50’ N latitude and 85°02’ and 85°58’ E longitude. The Bagmati River, non-glacial perennial river, consists of four main tributaries contributing from the northern part of the Bagmari River basin. They are the Manahara River, Bagmati River, Dhobi Khola and the Bishnumati River. The four major tributaries including the Bagmati River were upto sixth stream order. The study revealed that water discharge varied from 0.033 to 1.983 m3/s and the grain size distribution d50 ranged from 0.0002 to 0.0250 m. The study found that the suspended load for dry season varied from 5.93 to 916 mg/L and the bed load from 6 to 393711 tonnes/day. The total sediment yield ranged from 0.58 to 22029.64 tonnes/km2/day. The boundary shear stress and critical shear stress ranged from 0.03 to 30.87 N/m2 and 0.05 to 0.06 N/m2, respectively. The stream power per unit channel width was found to vary from 0.001 to 0.06 KNm/s/m2 for tributaries. Except at few sites, the rest of the sites of the studied river exhibit competency and good capability of sediment transport of the rivers. This study helps to implement proper engineering hydraulic practices around the river corridors.Bulletin of the Department of Geology, Vol. 19, 2016, pp. 29–44","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116660411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of aggregates from conglomerate beds of the Upper Siwalik Subgroup, Chure Khola area, Central Nepal Sub-Himalaya","authors":"Sunil Shanker Pradhananga, N. Tamrakar","doi":"10.3126/BDG.V19I0.19987","DOIUrl":"https://doi.org/10.3126/BDG.V19I0.19987","url":null,"abstract":"Durability of infrastructures demands detail study of rocks which helps to give knowledge on physical properties, strength and durability of rocks, and their usefulness as construction materials. A wide belt of conglomerates of the Upper Siwalik Subgroup (Pliocene to Lower Pleistocene) extends in the Chure Hills of Central Nepal. These conglomerates are mostly loosely consolidated, matrix-supported and containing clast of diverse composition. Because of haphazard mining of the riverbeds of the Chure and Dudhaura Kholas, the present study was carried out for evaluation of clasts from the conglomerates distributed at the hillslopes of the Chure Khola, as alternative sources mainly for unbound pavement. Stiffness and durability of clasts from conglomerates was tested for grading, shape indices, Water Absorption Value (WAV), specific gravity, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Los Angles Abrasion Value (LAV), Sodium Sulphate Soundness Value (SSSV) and Slake Durability Index (SDI). The suitability of clast from conglomerates for unbound pavement was finally evaluated for the sample for intended uses following specifications of British standard, ASTM standard and Nepal standard.The clasts of conglomerate beds are composed of quartzite, sandstone, siltstone, schist, marble, phyllite, granite, limestone and amphibolite. Among all those clasts, quartzite is dominant in all samples. The texture of clast is smooth and rough surface. Flakiness index (FI) and Elongation index (EI) indicate that aggregates possess only some flat and elongate grains and are good in workability. WAV lies below 3% and the dry density (2260kg/m3–2750kg/m3) of aggregates, coincides with the standard average value of ASTM Standard, British Standard and Nepal Standard. The ACV of the sample lies in the range 17% to 26% within the limit of ASTM standard, BS and Nepal Standard. The Los Angles Value of the sample lies in the range 34% to 44.60% and therefore, they can be used for base course and sub base course. SSSV for five cycles was calculated to be less than 10%. SDI after second cycle is very high (94.29%) and samples are durable in nature according to ASTM D4644- 87 Standard. All parameters show that the sample of the clast of conglomerate deposited along the Chure Khola are durable meeting all ASTM, British and Nepal Standard and thus are suitable unbound pavement.Bulletin of the Department of Geology,  vol. 19, 2016, pp. 1–14","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121545215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water Quality Index of southern part of the Kathmandu Valley, Central Nepal; evaluation of physical water quality parameters of shallow wells","authors":"Bimal Bohara","doi":"10.3126/BDG.V19I0.19989","DOIUrl":"https://doi.org/10.3126/BDG.V19I0.19989","url":null,"abstract":"Physical water quality of shallow groundwater of the southern part of the Kathmandu Valley was studied and analysed. Being the capital city of the country, the population is increasing day by dayand consequently the demand of water supply has also increased. Analyses reveal ranges of temperature to be 15.3–24.2 °C, pH to be 5.67–8.07, electrical conductivity to be (EC) 230–2860 μS/cm, and dissolved oxygen (DO) to be 0.09–9.1 mg/L in dry season whereas in wet season temperature, pH, EC and DO ranges are respectively 19.6–27.3 °C, 5.92–8.3, 183–3030 μS/cm and 0.19–7.9 mg/L. Water Quality Index (WQI) map shows that the upstream river areas contain good water quality than the downstream areas. The areas like Kalanki and Satdobato have poor water quality according to the guidelines of Nepal Drinking Water Quality Standard. Bulletin of the Department of Geology , Vol. 19, 2016, pp. 45–56","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123520013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Riverbank erosion potential and channel stability status of the Kodku River, southern Kathmandu Basin, Central Nepal","authors":"N. Tamrakar, R. Bajracharya, Sudarshon Sapkota, Ishwar Thapa, Prem Nath Paudel, Nira Tamang","doi":"10.3126/BDG.V17I0.12723","DOIUrl":"https://doi.org/10.3126/BDG.V17I0.12723","url":null,"abstract":"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/m 2 ), 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/m 2 ), 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.v17i0.12723 Bulletin of the Department of Geology, Vol. 17, 2014, pp. 1-41","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121217533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morpho-hydrologic parameters and classification of the Kodku River for stream stability assessment, southern Kathmandu, Central Nepal","authors":"N. Tamrakar, R. Bajracharya, I. Thapa, Sudarshon Sapkota, Prem Nath Paudel","doi":"10.3126/BDG.V16I0.8880","DOIUrl":"https://doi.org/10.3126/BDG.V16I0.8880","url":null,"abstract":"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","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"219 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123027523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rock Mass Rating and Geological Strength Index of rock masses of Thopal-Malekhu River areas, Central Nepal Lesser Himalaya","authors":"Jaya Singh, N. Tamrakar","doi":"10.3126/BDG.V16I0.8882","DOIUrl":"https://doi.org/10.3126/BDG.V16I0.8882","url":null,"abstract":"The rock slopes of the Thopal-Malekhu River areas, Lesser Himalaya, were characterized applying various systems of rock mass classification, such as Rock mass Rating (RMR) and Geological Strength Index (GSI), because the study area comprises well exposed rock formations of the Nawakot and Kathmandu Complexes, across the Thopal-Malekhu River areas. In RMR system, mainly five parameters viz. Uniaxial Compressive Strength (UCS) of rock, Rock Quality Designation (RQD), spacing of discontinuity, condition of discontinuity, and groundwater condition were considered. The new GSI charts, which were suitable for schistose and much disintegrated rock masses, were used to characterize rock slopes based on quantitative analysis of the rock mass structure and surface condition of discontinuities. RMR ranged from 36 to 82 (poor to very good rock mass) and GSI from 13.5±3 to 58±3 (poor to good rock mass). Slates (of the Benighat Slate) are poor rock masses with low strength, very poor RQD, and close to very close spacing of discontinuity, and dolomites (Dhading Dolomite) are fair rocks with disintegrated, poorly interlocked, and heavily broken rock masses yielding very low RMR and GSI values. Phyllites (Dandagaun Phyllite), schist (Robang Formation) and quartzite (Fagfog Quartzite, Robang Formation and Chisapani Quartzite), dolomite (Malekhu Limestone), and metasandstone (Tistung Formation) are fair rock masses with moderate GSI and RMR values, whereas quartzose schist and gneiss (Kulekhani Formation) are very good rock masses having comparatively higher RMR and GSI. The relationship between GSI and RMR shows positive and good degree of correlation. DOI: http://dx.doi.org/10.3126/bdg.v16i0.8882 Bulletin of the Department of Geology Vol. 16, 2013, pp. 29-42","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132987665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geotechnical properties of construction aggregates from the Trishuli Ganga River, Galchi area, Central Nepal","authors":"Shailendra Shrestha, N. Tamrakar","doi":"10.3126/BDG.V16I0.8883","DOIUrl":"https://doi.org/10.3126/BDG.V16I0.8883","url":null,"abstract":"The Trisuli Ganga River is rich in sand and gravel which are widely exposed along its banks. In recent years, quarry sites have been established and the materials have been supplied to markets. Apart from it the Trishuli III hydroelectric project is going to be established and for which a huge amount of construction aggregates will be required. From the study of sand and gravel as construction aggregates, it is found that the major composition of the sediments are metamorphosed rocks of the Lesser Himalayan rocks like gneiss, schist, quartzite, metasandstone, slate, granite, phyllite, etc. The gradation of coase aggregates range from dense to gap graded categories. Sulphate soundness value (SSV) and Los Angeles value (LAV) are 1.33–2.28% and 29.9–36.4%, respectively. These ranges show ability of the aggregates to resist weathering and abrasion, and since these values lie within international specifications, the aggregates are suitable for various uses as; both asphaltic and concrete aggregates. Considering the fine aggregates, though they contain considerable amount of quartz grains, also contain exceeding amount of mica, and possesses poor workablity. Fineness modulus ranges between 6.07 and 7.63, and exhibit dominantly sand size. Reduction of mica and further analysis for alkali-silica reactivity will enhance for its potential use. DOI: http://dx.doi.org/10.3126/bdg.v16i0.8883 Bulletin of the Department of Geology Vol. 16, 2013, pp. 43-52","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130620389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toppling and wedge failures in Malekhu River area, Malekhu, Central Nepal Lesser Himalaya","authors":"N. Tamrakar, Jaya Singh, K. Bista, Prayag Maharjan","doi":"10.3126/BDG.V16I0.8881","DOIUrl":"https://doi.org/10.3126/BDG.V16I0.8881","url":null,"abstract":"A huge landslide was identified on the right bank of the Malekhu River at about 1 km upstream from the Malekhu Bridge of the Prithvi Highway, and was named Malekhu Landslide. The landslide area consists of quartzite with sericite partings, chlorite schist and amphibolite of the Robang Formation of the Kathmandu Complex. The landslide extends for about 200 m along the river bank slope and its crown and toe have elevation respectively of 429 m and 361 m a.s.l. The major portion of the hillslope has been altered by landsliding as evidenced from the different geometry of slopes consisting of very steep scarp slope, steep to moderate slope with toppled and wedge failure debris, and several wedges and gullies. The right-side up layers have an average dip direction of 167° and a plunge of 56-90°, whereas the overturned layers have an average dip direction and plunge of 316°/32°. The direction towards which the toppling had occurred is 167°. The overturned layers had rotated to 36°, during which the layer dip direction had rotated counterclockwise to an amount of 31° from the major direction of toppling, and this rotation should have occurred during sliding of the toppled block. The Malekhu Landslide is a complex landslide experiencing more than one mode of failure of which the most prominent one is the toppling. It is a kind of flexural toppling of passive mode and had already occurred and now is suspended. The second mode of failure is the wedge sliding. The kinematic analysis of discontinuities on the slope for evaluating possibility of landsliding has indicated that the wedge failure is potential due to the presence of a line of intersection produced by the discontinuity parallel to the foliation of the right-side up layers and the overturned layers. This suggests that the toppled blocks may further slide. It is required to protect the slope from landsliding as there have been extended two unpaved roads one along the crown and the other along the toe of the landslide, and due to existence of the Malekhu Bridge in the downstream stretch of the river. DOI: http://dx.doi.org/10.3126/bdg.v16i0.8881 Bulletin of the Department of Geology Vol. 16, 2013, pp. 21-28","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127768499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithofacies and depositional environment of the Siwalik Group in Samari-Sukaura River area, Central Nepal","authors":"Dev Kumar Syangbo, N. Tamrakar","doi":"10.3126/BDG.V16I0.8884","DOIUrl":"https://doi.org/10.3126/BDG.V16I0.8884","url":null,"abstract":"Thick sedimentary sequence deposited in the foreland basin of the Nepal Himalaya is represented by the Siwalik Group. The Siwalik Group is well exposed in the Samari-Sukaura River area. The present study is focused in southern portion of the MBT around the Samari-Sukaura area for its depositional environment. The Middle Siwaliks of the Sukaura Road sections is overlained by the Lower Siwaliks which is separated by the Karki Khola Thrust. Extension of the Lower Siwaliks in the Jyamire Khola and the Bundal Khola becomes wider in the eastern Zone. Repetition of the Lower Siwaliks along the southern margin of the MBT is recognized. Depending on lithofacies assemblage and facies analysis, the two broad facies assemblages FA1 and FA2 have been distinguished. FA1 shows SB, FF, LA, LS and CH architectural elements and is interpreted as a product of the fine-grained meandering river system. FA2 shows SB, FF, LA, DA and CH architectural elements and is interpreted as a product of sandy mixed-load meandering river system. DOI: http://dx.doi.org/10.3126/bdg.v16i0.8884 Bulletin of the Department of Geology Vol. 16, 2013, pp. 53-64","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129004491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Landslide susceptibility analysis using decision tree method, Phidim, Eastern Nepal","authors":"Chandra Prakash Poudyal","doi":"10.3126/BDG.V15I0.7419","DOIUrl":"https://doi.org/10.3126/BDG.V15I0.7419","url":null,"abstract":"The decision tree is one of the new methods used for the determination of landslide susceptibility in the study area. The Phidim area is selected for the application of this method. The total surface area is 168.07 sq. km, and is located at the eastern part of Nepal. There are total of 10 different data bases used for this study which are; geological formation, elevation, slope, curvature, aspect, stream power index, topographic wetness index, distance from drainage, lineaments, and slope length, and are considered as landslide conditioning factors. Geographical information system (GIS) is used as basic tools and ARC/View is used for the processing data analysis and final map preparation. For the decision tree analysis the PASW 18 (statistical tool) is used to generate values of each factor. According to the results of decision tree, two geological formations; stream power index and slope are found as the most effective parameters on the landslide occurrence in the study area. Using the predicted values, the landslide susceptibility map of the study area is produced. To assess the performance of the produced susceptibility map, the area under curve (AUC) is drawn. The AUC value of the produced landslide susceptibility map has been obtained as 95.9%. According to the results of the AUC evaluation, the produced map has showed a good performance. As to wrap up, the produced map is able to be used for medium scaled and regional planning purposes. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7419 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 69-76","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121921631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}