Purushottam Adhikari, G. Srivastava, R. Mehrotra, Drona Adhikari, Keshav Shrestha, D. Uhl, K. Paudayal
Leaves of Terminalia (Combretaceae) and Daphnogene (Lauraceae) are described from the lower member of Lower Siwalik of Chatara- Barahakshetra area, eastern Nepal. The habit, habitat and present day distribution of the comparable extant taxa indicates the existence of tropical to sub-tropical evergreen to semi evergreen forest with humid climate in the area during the deposition of the Siwalik sediments. Bulletin of Department of Geology, vol. 20-21, 2018, pp: 21-28
{"title":"Leaf Impressions of Terminalia (Combretaceae) and Daphnogene (Lauraceae) from the Middle Siwalik of the Chatara-Barahakshetra Area, Eastern Nepal","authors":"Purushottam Adhikari, G. Srivastava, R. Mehrotra, Drona Adhikari, Keshav Shrestha, D. Uhl, K. Paudayal","doi":"10.3126/BDG.V20I0.20719","DOIUrl":"https://doi.org/10.3126/BDG.V20I0.20719","url":null,"abstract":"Leaves of Terminalia (Combretaceae) and Daphnogene (Lauraceae) are described from the lower member of Lower Siwalik of Chatara- Barahakshetra area, eastern Nepal. The habit, habitat and present day distribution of the comparable extant taxa indicates the existence of tropical to sub-tropical evergreen to semi evergreen forest with humid climate in the area during the deposition of the Siwalik sediments. Bulletin of Department of Geology, vol. 20-21, 2018, pp: 21-28","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130503634","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}
Palynological study from the Dharmasthali Formation exposed in the northern part of Kathmandu valley revealed the composition of forest vegetation that were growing in middle Pleistocene (780 kyrs BP) in this area. In a total fifteen samples were collected from the 46 m exposed section for the palynological study. The profile can be divided into two zones on the basis of pollen assemblages. The lower part (DF-I) is dominated by Pteridophyte spores such as Lygodium, Polypodium, Cyathea and Pteris. The dominance of Pteridophytes indicate that the forest floor was moist and humid. The tree pollen consists of Abies, Pinus, Quercus, Podocarpus and Alnus. Other Gymnosperms such as Picea and Tsuga were represented by very low percentage. Poaceae and Cyperaceae show their strong presence indicating grassland and wetland conditions around the depositional basin. In the upper zone (DF-II) there is increase of Gymnosperms such as Picea and Abies. The subtropical Gymnosperm Podocarpus decreased while Tsuga completely became absent in this zone. Cold climate preferring trees such as Cedrus, Betula, Juglans and Ulmus appeared first time in this zone. The climate became even colder and drier in the upper part of the section. Near water plants such as Cyperaceae and Typha show their dominance in this zone. The plant assemblages from bottom part of the Dharmasthali Formation indicate warm climate condition which was becoming colder after 780 kyrs towards the top part of the sequence. Bulletin of Department of Geology, vol. 20-21, 2018, pp:37-48
{"title":"Vegetation and Climate Around 780 Kyrs BP in Northern Kathmandu Valley, Central Nepal","authors":"S. Humagain, K. Paudayal","doi":"10.3126/BDG.V20I0.20722","DOIUrl":"https://doi.org/10.3126/BDG.V20I0.20722","url":null,"abstract":"Palynological study from the Dharmasthali Formation exposed in the northern part of Kathmandu valley revealed the composition of forest vegetation that were growing in middle Pleistocene (780 kyrs BP) in this area. In a total fifteen samples were collected from the 46 m exposed section for the palynological study. The profile can be divided into two zones on the basis of pollen assemblages. The lower part (DF-I) is dominated by Pteridophyte spores such as Lygodium, Polypodium, Cyathea and Pteris. The dominance of Pteridophytes indicate that the forest floor was moist and humid. The tree pollen consists of Abies, Pinus, Quercus, Podocarpus and Alnus. Other Gymnosperms such as Picea and Tsuga were represented by very low percentage. Poaceae and Cyperaceae show their strong presence indicating grassland and wetland conditions around the depositional basin. In the upper zone (DF-II) there is increase of Gymnosperms such as Picea and Abies. The subtropical Gymnosperm Podocarpus decreased while Tsuga completely became absent in this zone. Cold climate preferring trees such as Cedrus, Betula, Juglans and Ulmus appeared first time in this zone. The climate became even colder and drier in the upper part of the section. Near water plants such as Cyperaceae and Typha show their dominance in this zone. The plant assemblages from bottom part of the Dharmasthali Formation indicate warm climate condition which was becoming colder after 780 kyrs towards the top part of the sequence. Bulletin of Department of Geology, vol. 20-21, 2018, pp:37-48","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128294062","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}
Drona Adhikari, Keshav Shrestha, Purushottam Adhikari, K. Paudayal, L. Paudel
Geological mapping was carried out in the Chatara–Barahakshetra area of east Nepal. The Siwalik of the Chatara–Barahakshetra area is divided into the Lower Siwalik and the Middle Siwalik. Each unit is further subdivided into lower and upper members. The Central Churia Thrust is overturned in the study area. Highly deformed Siwalik contain several outcrop-scale as well as a large-scale folds. Bulletin of Department of Geology, vol. 20-21, 2018, pp: 49-58
{"title":"Geological Study of Chatara–Barahakshetra Section, Sunsari-Udayapur District, Eastern Nepal","authors":"Drona Adhikari, Keshav Shrestha, Purushottam Adhikari, K. Paudayal, L. Paudel","doi":"10.3126/BDG.V20I0.20723","DOIUrl":"https://doi.org/10.3126/BDG.V20I0.20723","url":null,"abstract":"Geological mapping was carried out in the Chatara–Barahakshetra area of east Nepal. The Siwalik of the Chatara–Barahakshetra area is divided into the Lower Siwalik and the Middle Siwalik. Each unit is further subdivided into lower and upper members. The Central Churia Thrust is overturned in the study area. Highly deformed Siwalik contain several outcrop-scale as well as a large-scale folds. Bulletin of Department of Geology, vol. 20-21, 2018, pp: 49-58","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"2140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130005147","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}
Population growth and intense agricultural activities in Nepal has caused substantial increase in demand for fresh water. As there is limited access to surface water in most parts of the country, groundwater and springs are the principal water sources for irrigation and drinking purposes in the Terai and hilly region, respectively. The present study carries out the water quality analysis of 30 spring samples in the Badigad Catchment from Gulmi and Baglung Districts. The study was made to analyse suitability of spring waters of the Badigad Catchment for irrigation and drinking purposes. The physiochemical parameters were analysed using standard methods in the site and laboratory. Average value for pH of the sample was 7.8 with conductivity value ranging from 630 to 1500 micro Siemens/cm. The bicarbonate alkalinity ranges from 140 to 350 mg/L, indicating a medium salinity hazard in the catchment. The water in the catchment was found to be moderately hard with an average of 75mg/L CaCO3 hardness. Nitrate, sulphate, ammonia, chloride, fluoride and sodium absorption ratio were found to be <0.1mg/L, <1mg/L, <1.5mg/L, 3mg/L, 1mg/L and <2, respectively in all samples. Iron content in the water was also below the permissible limits in some samples and not available in some samples. Thus, the spring water in Badigad Catchment is suitable for drinking and irrigation purposes. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 67-74
{"title":"Water quality of springs in Badigad Catchment, Western Nepal","authors":"Jivan Bhusal, P. Gyawali","doi":"10.3126/BDG.V18I0.16458","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16458","url":null,"abstract":"Population growth and intense agricultural activities in Nepal has caused substantial increase in demand for fresh water. As there is limited access to surface water in most parts of the country, groundwater and springs are the principal water sources for irrigation and drinking purposes in the Terai and hilly region, respectively. The present study carries out the water quality analysis of 30 spring samples in the Badigad Catchment from Gulmi and Baglung Districts. The study was made to analyse suitability of spring waters of the Badigad Catchment for irrigation and drinking purposes. The physiochemical parameters were analysed using standard methods in the site and laboratory. Average value for pH of the sample was 7.8 with conductivity value ranging from 630 to 1500 micro Siemens/cm. The bicarbonate alkalinity ranges from 140 to 350 mg/L, indicating a medium salinity hazard in the catchment. The water in the catchment was found to be moderately hard with an average of 75mg/L CaCO3 hardness. Nitrate, sulphate, ammonia, chloride, fluoride and sodium absorption ratio were found to be <0.1mg/L, <1mg/L, <1.5mg/L, 3mg/L, 1mg/L and <2, respectively in all samples. Iron content in the water was also below the permissible limits in some samples and not available in some samples. Thus, the spring water in Badigad Catchment is suitable for drinking and irrigation purposes. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 67-74","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132102130","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}
The Malekhu Khola is rich in sediments which are widely exposed along its banks. In recent years, river mining sites have been established and mining has been carried on to produce aggregates to meet a small portion of the market demand. Because the riverbank deposits are of heterogeneous composition, quality of the aggregate from such deposits is of main issue. This study therefore, aims to evaluate quality of river sediment to know its suitability for aggregate as raw material for various uses, and the volume of the deposit. Field observation and intensive laboratory works were carried out to evaluate aggregates. The samples of aggregates were analyzed for texture, composition, durability and physical and mechanical properties. Majority of the aggregate particles were found metamorphic rocks of the Lesser Himalaya like quartzite, schist, marble, metasandstone, amphibolites, gneiss and granite, etc. Most of the deposits were matrix-supported and the matrix was basically sandy. The majority of clasts showed bladed to disc, and were generally rounded to sub rounded. The sediment size ranged from granule to upto boulder but the modal size was of cobble grade. While tested for gradation, the coarse aggregates ranged from uniform to gap graded categories. In terms of shape, workability of aggregate was found satisfactory. Aggregate samples possessed low Water Absorption Value (0.53–1.08%) and thus low effective porosity. Aggregate Impact Value (13.40–15.70%) and Aggregate Crushing Value (17.50–19.67%) showed good soundness. Los Angeles Abrasion Value (37.00–48.40%) showed the consistent hardness of each of the samples. The low range of Sodium Sulphate Soundness Value (1.37–2.16%) indicated good resistance of aggregates against chemical weathering and frosting. The aggregates were also resistant to slaking as indicated by very high range of Slake Durability Strength Index (98.67–99.72%). Comparing with the existing Nepal Standard (NS), British Standard (BS) and American Standard of Testing Material (ASTM), the studied samples were suitable for concrete structures and unbound pavements. Six different localities were considered in the study area to estimate for resource of aggregates. The total volume of the deposits was estimated to be 392273 cubic meter. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 49-58
{"title":"Qualitative and quantitative assessment of gravel deposits between Aaptar and Malekhu, Central Nepal for aggregates","authors":"Sunu Dawadi","doi":"10.3126/BDG.V18I0.16456","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16456","url":null,"abstract":"The Malekhu Khola is rich in sediments which are widely exposed along its banks. In recent years, river mining sites have been established and mining has been carried on to produce aggregates to meet a small portion of the market demand. Because the riverbank deposits are of heterogeneous composition, quality of the aggregate from such deposits is of main issue. This study therefore, aims to evaluate quality of river sediment to know its suitability for aggregate as raw material for various uses, and the volume of the deposit. Field observation and intensive laboratory works were carried out to evaluate aggregates. The samples of aggregates were analyzed for texture, composition, durability and physical and mechanical properties. Majority of the aggregate particles were found metamorphic rocks of the Lesser Himalaya like quartzite, schist, marble, metasandstone, amphibolites, gneiss and granite, etc. Most of the deposits were matrix-supported and the matrix was basically sandy. The majority of clasts showed bladed to disc, and were generally rounded to sub rounded. The sediment size ranged from granule to upto boulder but the modal size was of cobble grade. While tested for gradation, the coarse aggregates ranged from uniform to gap graded categories. In terms of shape, workability of aggregate was found satisfactory. Aggregate samples possessed low Water Absorption Value (0.53–1.08%) and thus low effective porosity. Aggregate Impact Value (13.40–15.70%) and Aggregate Crushing Value (17.50–19.67%) showed good soundness. Los Angeles Abrasion Value (37.00–48.40%) showed the consistent hardness of each of the samples. The low range of Sodium Sulphate Soundness Value (1.37–2.16%) indicated good resistance of aggregates against chemical weathering and frosting. The aggregates were also resistant to slaking as indicated by very high range of Slake Durability Strength Index (98.67–99.72%). Comparing with the existing Nepal Standard (NS), British Standard (BS) and American Standard of Testing Material (ASTM), the studied samples were suitable for concrete structures and unbound pavements. Six different localities were considered in the study area to estimate for resource of aggregates. The total volume of the deposits was estimated to be 392273 cubic meter. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 49-58","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132257114","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}
Infrastructures such as road, building, cannals, dam, bridges and so on lie on geological bases. Durability of the structures demands detail study of rocks in microscopic level. Such study helps to give knowledge about strength and physical properties of rocks, and their usefulness as construction materials. Index properties are the basic parameters to be found out before the developent of engineering structures, and are governed by the texture of the rock such as grain interlocking, crystallinity, shape factor, grain size homogeneity, grain orientation, micro fractures, etc. Textural study of the samples gave the micropetrographic quality index ranging from 0.05 to 49, grain size homogeneity from 0.06 to 0.74, interlocking index ranging from 7 to 92% and texture coefficient ranging from 1.08-1.97. Micropetrographic index has great influence on porosity and point load strength index. Siliceous rocks having high texture coefficient are mechanically sound. When homogeneity in grain size, shape and orientation increases, texture coefficient tends to diminish. Therefore, texture coefficient is an important variable. Dry density of samples ranges from 2309 to 3224 kg/m3, porosity from 0.08 to 8.91% and point load index from 0.26 to 13.13 MPa. Water Absorption Value (WAV) is entirely below 2% except for the slates indicating that most of the rocks have low effective porosity. Strength of rocks varies from very low to very high. Considering the texture and index properties, the rock types suggested for the construction aggregates are quartzites of the Nourpul Formation, the Fagfog Quartzite, and the Chisapani Quartzite, and psammitic schist of the Robang Formation. The quartzite samples from the Fagfog and the Norpul Formations are useful for silica sources. Siliceous dolomite ‘Np3’ of the Nourpul Formation and dolomite ‘Ml1’ of the Malekhu Limestone also show good interlocking, high density and high strength. Bulletin of the Department of Geology Vol. 18, 2015, pp. 1–14
{"title":"Texture and index properties of rocks from Malekhu-Thopal Khola area, Central Nepal Lesser Himalaya","authors":"Prayag Maharjan","doi":"10.3126/BDG.V18I0.16453","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16453","url":null,"abstract":"Infrastructures such as road, building, cannals, dam, bridges and so on lie on geological bases. Durability of the structures demands detail study of rocks in microscopic level. Such study helps to give knowledge about strength and physical properties of rocks, and their usefulness as construction materials. Index properties are the basic parameters to be found out before the developent of engineering structures, and are governed by the texture of the rock such as grain interlocking, crystallinity, shape factor, grain size homogeneity, grain orientation, micro fractures, etc. Textural study of the samples gave the micropetrographic quality index ranging from 0.05 to 49, grain size homogeneity from 0.06 to 0.74, interlocking index ranging from 7 to 92% and texture coefficient ranging from 1.08-1.97. Micropetrographic index has great influence on porosity and point load strength index. Siliceous rocks having high texture coefficient are mechanically sound. When homogeneity in grain size, shape and orientation increases, texture coefficient tends to diminish. Therefore, texture coefficient is an important variable. Dry density of samples ranges from 2309 to 3224 kg/m3, porosity from 0.08 to 8.91% and point load index from 0.26 to 13.13 MPa. Water Absorption Value (WAV) is entirely below 2% except for the slates indicating that most of the rocks have low effective porosity. Strength of rocks varies from very low to very high. Considering the texture and index properties, the rock types suggested for the construction aggregates are quartzites of the Nourpul Formation, the Fagfog Quartzite, and the Chisapani Quartzite, and psammitic schist of the Robang Formation. The quartzite samples from the Fagfog and the Norpul Formations are useful for silica sources. Siliceous dolomite ‘Np3’ of the Nourpul Formation and dolomite ‘Ml1’ of the Malekhu Limestone also show good interlocking, high density and high strength. Bulletin of the Department of Geology Vol. 18, 2015, pp. 1–14","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132660548","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}
The Malekhu Khola is accessible and potential for the construction materials in today’s developing phase. The study mainly concerns with mining of construction aggregate and effect of indiscriminate mining from river and its basin area which may impose many harmful effects on environment. The objective of the study is to identify the condition of river using morphological and physical parameters, and to investigate the factors which are directly responsible for the environmental degradation. Such study of rivers in present context is essential as it provides insights of strength of the river. To examine the circumstance of river, the study was proceed by selecting the area into three reaches of each 500 m, and further each reaches are divided into six transects. Both reach-scale and transect-scale attributes were assessed. The scoring was done by adding all the attributes of the standard survey sheet. A cross-sectional study was carried out along 3 different stations, Reach 1 to Reach 3 from upstream to downstream. Various fluvial parameters and data from pebble count were used to calculate morphological parameter and grain size distribution. The channel sediments were found to be extremely poorly sorted, the distribution of grain size is varied from transect to transect, which might be the result of unplanned mining. All the result acquired from field study and satellite image confirms that the river is worsening day by day. The formation of pools and deposition of organic matter show that the river is not flowing in its natural way. After all the examination, it indicates that the Malekhu Khola is being violated by the human and mining activities, thus the river reclamation measure is required at abandoned mining sites to maintain the Malekhu Khola channel morphology and habitat of the river. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 59-66
{"title":"Alluvial mining and its impact on deterioration of physical health of Malekhu Khola, Central Nepal","authors":"J. Khanal","doi":"10.3126/BDG.V18I0.16457","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16457","url":null,"abstract":"The Malekhu Khola is accessible and potential for the construction materials in today’s developing phase. The study mainly concerns with mining of construction aggregate and effect of indiscriminate mining from river and its basin area which may impose many harmful effects on environment. The objective of the study is to identify the condition of river using morphological and physical parameters, and to investigate the factors which are directly responsible for the environmental degradation. Such study of rivers in present context is essential as it provides insights of strength of the river. To examine the circumstance of river, the study was proceed by selecting the area into three reaches of each 500 m, and further each reaches are divided into six transects. Both reach-scale and transect-scale attributes were assessed. The scoring was done by adding all the attributes of the standard survey sheet. A cross-sectional study was carried out along 3 different stations, Reach 1 to Reach 3 from upstream to downstream. Various fluvial parameters and data from pebble count were used to calculate morphological parameter and grain size distribution. The channel sediments were found to be extremely poorly sorted, the distribution of grain size is varied from transect to transect, which might be the result of unplanned mining. All the result acquired from field study and satellite image confirms that the river is worsening day by day. The formation of pools and deposition of organic matter show that the river is not flowing in its natural way. After all the examination, it indicates that the Malekhu Khola is being violated by the human and mining activities, thus the river reclamation measure is required at abandoned mining sites to maintain the Malekhu Khola channel morphology and habitat of the river. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 59-66","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128160256","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}
Aggregate, the inert materials used in almost every field of modern development structures have great influence. Aggregates may look similar in appearance but they may carry different physical, mechanical and chemical properties and they may perform accordingly. End uses of aggregates are also determined by their performance. The Lesser Himalaya of the Malekhu- Thopal area comprises more than 14 formations having great potential of rock aggregates. The present study was carried out in order to reveal the toughness and soundness of each rock type of the Lesser Himalaya so that durability can be determined. Altogether 25 representative samples were tested to find porosity, specific gravity, dry density, uniaxial compressive strength (UCS), Los Angeles abrasion value (LAAV), aggregates impact value (AIV), sodium sulphate soundness Value (SSSV), ethylene glycol soaking value and water absorption value (WAV). Results were compared with standards of different specifications and recommended for wide range end uses. Rock mass rating of each formation was carried out and the value ranges from 36 to 82. Specific gravity ranges from 2.08 to 3.08 and the dry density ranges from 2.3 to 3.22 g/cm3. All the samples have porosity less than 2% except the samples of the Benighat Slate. UCS value ranges from 5.9 to 301.9 MPa. The LAAV of the sample lies between 19.6% and 47.5%. AIV is between 8.54% and 34.28%. The SSSV ranges from 2.35 to 26.06%. Ethylene glycol soak index is 2 of all samples signifying that proportion of swelling clays or low accessibility of ethylene glycol through the samples due to low porosity. WAV of all the samples is below 2% except the Benighat Slates which indicates that the aggregates have low effective porosity. The entire test shows that most of the sample meets different national and international standards and can be recommended for wide range of end uses. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 15–34
{"title":"Evaluation of strength and durability of rocks from Malekhu-Thopal Khola area, Central Nepal Lesser Himalaya for construction aggregates","authors":"K. Bista, N. Tamrakar","doi":"10.3126/BDG.V18I0.16454","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16454","url":null,"abstract":"Aggregate, the inert materials used in almost every field of modern development structures have great influence. Aggregates may look similar in appearance but they may carry different physical, mechanical and chemical properties and they may perform accordingly. End uses of aggregates are also determined by their performance. The Lesser Himalaya of the Malekhu- Thopal area comprises more than 14 formations having great potential of rock aggregates. The present study was carried out in order to reveal the toughness and soundness of each rock type of the Lesser Himalaya so that durability can be determined. Altogether 25 representative samples were tested to find porosity, specific gravity, dry density, uniaxial compressive strength (UCS), Los Angeles abrasion value (LAAV), aggregates impact value (AIV), sodium sulphate soundness Value (SSSV), ethylene glycol soaking value and water absorption value (WAV). Results were compared with standards of different specifications and recommended for wide range end uses. Rock mass rating of each formation was carried out and the value ranges from 36 to 82. Specific gravity ranges from 2.08 to 3.08 and the dry density ranges from 2.3 to 3.22 g/cm3. All the samples have porosity less than 2% except the samples of the Benighat Slate. UCS value ranges from 5.9 to 301.9 MPa. The LAAV of the sample lies between 19.6% and 47.5%. AIV is between 8.54% and 34.28%. The SSSV ranges from 2.35 to 26.06%. Ethylene glycol soak index is 2 of all samples signifying that proportion of swelling clays or low accessibility of ethylene glycol through the samples due to low porosity. WAV of all the samples is below 2% except the Benighat Slates which indicates that the aggregates have low effective porosity. The entire test shows that most of the sample meets different national and international standards and can be recommended for wide range of end uses. Bulletin of the Department of Geology, Vol. 18, 2015, pp. 15–34","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127068120","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}
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
{"title":"Fluvial morphology and sediment transport of the Malekhu Khola, Central Nepal Lesser Himalaya.","authors":"Nira Tamang, N. Tamrakar, M. Magar, M. Raut","doi":"10.3126/BDG.V18I0.16455","DOIUrl":"https://doi.org/10.3126/BDG.V18I0.16455","url":null,"abstract":"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","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132812168","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}
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
{"title":"Fluvial morphology and dynamics of the Godavari Khola, southeast Kathmandu, Central Nepal","authors":"S. Karki, N. Tamrakar","doi":"10.3126/BDG.V19I0.19990","DOIUrl":"https://doi.org/10.3126/BDG.V19I0.19990","url":null,"abstract":"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","PeriodicalId":356325,"journal":{"name":"Bulletin of The Department of Geology","volume":"70 5-6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132693269","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}
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