Geology

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Depth to Gravel Layer Mapping to determine Potential Areas of Artificial Groundwater Recharge in Patan Area
(Department of Geology, 2012) Maharjan, Ganga Ram
Groundwater has been extensively used in Kathmandu Valley through dug wells, ponds and dhunge dharas (stone spouts) since ancient period. Shallow groundwater was tapped through dug wells and dhunge dharas. Rapid urbanization and increasing demand have however put enormous stress on the traditional water supply system especially as current municipal water supply barely fulfills 25% of the demand. Even in those days, recharge ponds were made and water was brought from the valley rims through long canals to recharge the system. Local geology and the geomorphologic factors influencing the infiltration and recharge rates. Points located on terraces have relatively higher infiltration rates than those located on low lands due to high water level in lowlands which rejects rainwater recharge. The areas around Jawalakhel, Gabahal, Kumaripati and Lagankhel in Patan show immense potential for rainwater recharge. As dug wells and shallow tube wells have higher recharge rates than the pits and infiltrometers due to their access directly to the aquifer horizons, dug wells would be good structures for recharging shallow groundwater even in places lies in Kalimati Formation. More than 50% of the study area is high recharge potential area which mostly covers in the Southern and Western part of the study area according to the geology, topography and infiltration rate of the region. The percentage of coarse material is about 90% at Lagankhel area especially Patan Hospital periphery and infiltration rate is 1.2 cm/min which is relatively higher than other study area. It is concluded that Lagankhel area is more feasible than others.
Estimation of Dynamic and Liquefaction Properties by Shear Wave Velocity
(Department of Geology, 2009) Gautam, Suman
The analysis of foundation vibrations and geotechnical earthquake engineering problems in civil engineering requires characterization of dynamic soil properties using geophysical methods. Dynamic structural analysis of the superstructures also requires knowledge of the dynamic response of the soilstructure, which in turn relies on dynamic soil properties. Geophysical methods are often used to characterize the dynamic soil properties of the subsurface. This method requires a borehole through which a sensing probe is lowered at known level. Source near the borehole is generated artificially with the help of wooden plank and hammer. The seismogram obtained from computer aided system is used to determine shear wave velocity and compressive wave velocity which is further used to calculate dynamic parameters such as Poisson’s ratio, dynamic shear modulus, dynamic elastic modulus and predominant period etc. Ground water table is very close to ground surface and the soil is mainly fine to coarse sand with some intermittent layers of cohesive soils meaning that the soil is very liable to liquefaction. Liquefaction resistance is assessed in terms of cyclic stress ratio and in terms of factor of safety both of which show that the liquefaction potential of the site is very high mainly near shallow depth less than 10m.
Geological Study of the Mardi River Section from Upallo Dip to Ramche, Lesser Himalaya, Western Nepal
(Department of Geology, 2014) Neupane, Amit
Geological mapping and petrographic study were carried out along the Mardi River from the Dip to Ramche. The area is covered by the rocks of the Lesser Himalaya in the south and the Higher Himalaya in the north separated by the Main Central Thrust (MCT). The Kuncha Formation consists of chlorite-phyllite and metasandstone, which is underlain by the Fagfog Quartzite. The Fagfog Quartzite consists of white quartzite and two band of amphibolite intrusion, above this lies the Marble and Schist having medium grained garnet. The Black Schist and Quartzite lies over the Marble and Schist. All these terminate over the garnet and kyanite bearing schist and gneiss namely the Kyanite banded Gneiss. The lower boundary of the formation is supposed to be the Main Central Thrust (MCT). Hence in the area the Lesser Himalaya contains four units and the Higher Himalaya contains one unit. The biotite grade zone starts from the Dip, lowest part of the area which is underlain by the garnet zone. The garnet grade zone starts from the Saiti Ghatta Khola and terminates in the MCT, from that kyanite grade zone is initialized. The foliation in the area mostly dips towards NE except in the areas of local folding. Foliation is less prominent and usually parallel and sub parallel to the bedding. The area contains folds, thrust, stretching lineation and boudinage in the lesser Himalaya rocks. From the petrographic study, it is depicted that the metamorphism in the area is the inverse prograde type. The higher grade metamorphic mineral is found stratigraphically high.
Geological, Engineering Geological and Geotechnical Studies of the Upper Trishuli – 2 Hydroelectric Project Rasuwa, Central Nepal
(Department of Geology, 2012) Shrestha, Kedar
The Upper Trishuli – 2 Hydroelectric Project is located on the northern part of Rasuwa District, Central Nepal. Geographically, the study area extends from longitude 85° 17' 44" E to 85° 20' 37" E and latitude 28° 07' 36" N to 28° 10' 06" N. Its estimated capacity is 100 MW with net head of about 98 m. The study is concerned with geological, engineering geological and geotechnical studies of the Upper Trishuli – 2 Hydroelectric Project. The rocks of the area belong to the Ranimatta Formation, Midland Group of Lesser Himalayan succession. They comprise quartzite, phyllite and schist. Most of the area comprise higher proportion of quartzite than that of phyllite The foliation plane of the area is along (020° to 040°) with dip amount of (45° to 30°). All the hydraulic structures lie within the bedrock. The structures like desander basin and powerhouse are underground. The headrace tunnel alignment passes through two passive faults namely, Syo Khola Fault and Gre Khola Fault. Adjusted RMR and Q ranges from 46 to 64 and 1.68 to 8.66 respectively. Generally, rocks belong to poor to fair rock class. Geotechnical studies include preliminary stress analysis and rock support design along the underground structures. Average in-situ deformation modulus ranges from 6.7865 to 22.719. Vertical and horizontal stress as well as horizontal to vertical ratio ranges from 0.74-3.9394, 1.5029-5.7050 and 0.623-3.262 respectively. Damage index varies from 0.0367 to 0.1158. Support design for construction of the headrace tunnel based on different system suggests the combination of local to systematic bolting and reinforced shotcrete as per requirement. Geophysical survey shows the thickness of alluvial and colluvial overburden ranges from 15 m to 60m. Construction material can be extracted from 14 sites while 4 sites are suitable for muck disposal.
Geology and Mineral Resources of the Bandipur Area, Lesser Himalaya, Central Nepal
(Department of Geology, 2011) Maharjan, Naresh
The present study was carried out around the Bandipur-Hilekharka-Keshavtar areas, west of Muglin, Central Nepal, Lesser Himalaya in an attempt to draw the stratigraphic set up, tectonic structures and mineral resources of the area. It consists of the rocks of the Nawakot Complex. The Fagfog Quratzite is the oldest unit of Lower Nawakot Group which is followed by the Dandagaon Phyllite, Nourpul Formation and Dhading Dolomite in successively higher positions and the Benignat Slate of Upper Nawakot Group but the Malekhu Limestone is missing in the study area. Based on lithology and environment of deposition, Nourpul Formation has been mapped into four members as Purebensi Quartzite, Amdanda Phyllite (laminated phyllile) and Labdi Khola Carbonate (observed in LabdiKhola areas) and Bandipur Slate (observed in Bandipur areas). The monotonous sequence of Carbonaceous Phyllite, well exposed on LabdiKhola-Mastipur section, poorly resembles with Benighat Slate of the type locality. Different types of erosional and tectonic structures are mapped in the study area. The Dadagaon Phyllite shows a broad inlier around Chipleti area and a small elliptical outlier of Purebensi Quartzite is mapped in Hilekharka area. A prominent thrust contact is mapped in between Dhading Dolomite and Nourpul Formation continuously around Chandrakot, Ripthok, Tilahar, Takmare and Kamalbari areas which is named as Jal Bhanjyang Thrust in present study. Two major folds viz. Bandipur Syncline and Hilekharka Anticline are also observed in the territory. Different types of sedimentary structures like ripple marks; mudcracks and graded beddings show the right side up sequence of the different units. A large number of tight isoclinal folds with folded quartz veins are observed in the Carbonaceous Phyllite of Benighat Slate. The rock units of the area consist of pelitic, psammatic and calcareous metasediments up to chlorite/sericite grade of metamorphism. Basic plutonic rocks are intruded in the upper part of Nourpul Formation which is sill like in nature and mappable in the field. Different types of both metallic and non-metallic minerals are found in the study area. Among them, copper deposit of Bhut Khola, hematite of Labdi Khola, roofing quality slate of the Bandipur and graphite deposit of Ghumaune-Labdi section are the potential resources of the area.
Geology and Structure of the Kota-Baidi Area, Tanahu District, Central Nepal, Lesser Himalaya
(Department of Geology, 2011) Limbu, Deo Kumar
The study area is a part of the Lesser Himalaya, central Nepal along the Kota-Baidi area of the Tanahu District. The aim of the study was to prepare a detailed geological map of the area in the scale of 1:25,000. The study area consists of both the rocks of Upper and Lower Groups of the Nawakot Complex, their age ranging from Late Precambrian to Early Paleozoic. The rocks of the Lower Nawakot Group consist of the Nourpul Formation and the Dhading Dolomite whereas the Upper Nawakot Group consists of the Benighat Slate and the Robang Formation. The Malekhu Limestone is missing in the area and the Benighat Slate is not found in normal stratigraphic position which is thrust over the younger sequence, the Robang Formation. The Nourpul Formation consists of mixed type of metasedimentary rocks like shale, mudstone, phyllite, metasandstone, dolomite and quartzite. Occasionally these rocks consist of sedimentary structures like mudcracks and ripple marks pointing right-way-up of the beds. Stratigraphically, the Nourpul Formation is followed upwards by the Dhading Dolomite. It consists of ridge forming stromatolitic dolomite with subordinates of phyllites and quartzites. The well developed columnar stromatolites of this formation show the beds to be in the normal position. The Benighat Slates is characterized by the monotonous sequence of grey to dark grey slate and phyllite with or without calcareous deposits. Based on the calcareous nature, a separate member has been mapped within the Benighat Slate as the Jhiku Carbonates. The youngest sequence of the area is mapped as the Robang Formation, consisting of intercalation of phyllite, metasandstone and quartzite with several bands of metabasites. The whole study area lies in the core of megasyncline which is named as Kota-Baidi Syncline. It is a tightly strike-out syncline whose trend and plunge is about 277°/17°. Another significant local fold is mapped as Makre Anticline whose trend and plunge is found to be 284°/8°. Two major thrust structures of the area are the Main Boundary Thrust (MBT) in the south and the Chherenga Khola Thrust, nearly parallel to the MBT, in the north. The MBT can be easily demarcated in the field based on lithology and topography whereas the Chherenga Khola Thrust is recognized only on the basis of abrupt change in lithological formations. Numerous mesoscopic folds and faults in different orientations, sedimentary structures, quartz veins, boudinages and pockets of several minerals are also recorded in the field.
Geology, Mining and Processing of Okhare Limestone Deposit, Hetauda Central Nepal
(Department of Science and Technology, 2008) Banjade, Bharat
The purpose of the study is to clarify the regional geology around Okhare Limestone Deposit, to evaluate the quality and reserve of Okhare deposit, and having a general understanding of mining and processing of Limestone by HCIL. About 59 km 2 area was mapped during the fieldwork. Three limestone deposits was studied during this work: Okhare, Bhainse and Majuwa. Okhare and Bhainse belongs to the Okhare-Kitni range of Bhainsedobhan Marble and Majuwa Limestone belongs to the Jhiku Bed of Benighat Slate. The study area is separated by two thrusts MBT and MT and divided into three tectonic zones. Southern part of the area consists of sedimentary rocks of Siwalik Group, which followed to the north by low-grade metamorphic rocks of Midland Group and around Bhainse area, northern part of the study area, medium to high - grade metamorphic rocks of Bhimphedi Group are exposed. The general trend of the rocks of the study area is NW-SEwith dip amount being around 40 0 –75 0 . The area is of high tectonic activity because of the presence of MBT, MT, numerous folds, faults and landslides in the area. Okhare Limestone Deposit is a sedimentary-metamorphic deposit showing well developed crystals of calcite presenting as a outlier at the top of the Chattre Bhanjyang hill. Okhare deposit consists of light to dark-grey, medium to coarse-grained Limestone bands which vary in the content of Cao% and Sio . Phyllitic Limestone is its notable characteristic.Phyllite is present as spot, lenses within the bed and coatings on the bedding plane looking phyllitic bed. The strike of the bed is NWW–SEE and average dip amount being45 0 2% with 46.5% of Cao and 1.30% of Mgo with the hill slope of 50-75 . Reserve of the deposit was estimated by cross-sectional method.Total reserve is 15.33 million ton with 13million ton at 85% recovery factor. The ratio of volume of Limestone to waste is 1:0.32. Area above 1900m (above sea level) of the area is proposed for mining with the area of1,90,000 sq.m. This deposit is not yet been worked. Okhare deposit will be worked by opencast method with bench cut as quarrying method. 5m height and 20–25m width benches with at least two quarry face will be made for quality control. Drilling, blasting and loading are main works in mining. Limestone is processed from mine to packing unit as cement through Primary Crusher,Secondary Crusher, Mixing Hopper, Grinding Mill, Blending Silo, Rotary Kiln, Clinker Silo, Cement Mill Silo and Packing Unit.
Geotechnical and Geophysical Investigations with Pga Estimation of the Kathmandu Fun Park Project, Thankot, Kathmandu, Nepal
(Department of Geology, 2014) Rijal, Ashim
This work focuses on the study of the foundation characteristics by geotechnical and geophysical investigations with PGA estimation of the Kathmandu Fun Park Project (KFPP) located in Thankot area, Kathmandu. To obtain information on subsurface material, velocity distribution and soil thickness seismic refraction survey was conducted using a 24 channel seismograph system by Oyo. Other soil properties were studied by in-situ Direct Cone Penetration Test (DCPT) and laboratory test of samples. The problem of ground shaking in the case of large earthquake near the Kathmandu valley is assessed in terms of synthetic peak ground acceleration (PGA) due to the lack of observed data. The present study provides tools for estimating geotechnical parameters from seismic wave velocity in the area where soil test are difficult to conduct. Fewer amounts of observed data and unavailability of instruments for undisturbed sampling have somehow affected this research work. Manual picking of travel time data from waveforms has affected the subsequent processing and interpretation of seismic refraction data. The study area comprises of colluvium deposits, mainly washout with high clay content. The high moisture content, low unconfined compressive strength and low bearing capacity of the soil are noteworthy. A modeled equation relating the P-wave velocity and porosity for the Lesser Himalayan colluvium soil has been established together with the material velocity. Similarly, the PGA distribution due to 1934 Taplejung, 1988 Udayapur and other two hypothetical earthquakes shows the PGA may exceed 150 gal for earthquakes greater than magnitude 8. However, the result shows the PGA hardly reach 15 gal for small but strong earthquakes. Moreover, the geotechnical parameters, specially moisture content, unconfined compressive strength, friction angle and porosity, show reasonably good correlation with seismic P-wave velocity. The single field measurement (i.e. seismic P-wave velocity) can serve the best for estimating other geotechnical parameters.
Hydrogeologic Assessment and Groundwater Reserve Evaluation in Parts of the Dun Valley Aquifers of Chitwan, Inner Terai
(Department of Geology, 2009) Neupane, Rajendra
The Chitwan Valley is one of the largest Dun Valleys in the Himalayan foothills. The Siwalik Domain was affected by neotectonic movement in the last 1.6 m.y. the stream impoundment of sizeable volumes of gravel filled up in the lakes forming intermontane flat stretches called Duns. The Dun gravels perhaps deposited in the late Pleistocene to very early Holocene about 22,000-7000 yr. B.P. Classification of river terraces in the study area are into six groups. Higher and highest terraces are related to during Pre-last interglacial time. Formation of many wetlands and oxbow lakes occurs in the flood plain of Khageri—Rapti— Narayani River. Westward shift of present Narayani River is clearly evidenced by the continuation of wetlands parallel to main river course. These depressions belong to an old abandoned channel revealed the ramification of Naryani in west Chitwan. The study area lies in the western part of the Valley and is covered with alluvial deposits. The grain size of the alluvium gradually decreases from the north to the south. In the sub-surface, clay, silt, sand and gravel layer with different proportion have been noticed, the sediments distribution is relatively homogeneous. Principal aquifer materials are sand, gravel, pebble; even cobble and boulder are found in unconfined and semi-confined or leaky aquifer condition. Annual Potential Evapotran spiration (PET) at Rampur (cropland surface) is 1.68 mm/day and that at Devghat (water surface) is 2.37mm/day are found. Annual precipitation recorded at Rampur station is 2214mm, area of recharge is about 70.8 km 2. . An average water table fluctuation in 98 dug wells over the study area is 2.21m. It ranges from 0.1 m to 6.85 m. Therefore estimation of total groundwater storage in the study area on both confined and unconfined condition is 87.31 MCM per year and potential recharge by applying Duba’s estimation is 48.60 MCM per year. The study area comprises single to multi layer aquifer horizons. The thickness of aquifer varies from 2m. to more than 30m.The potentiality of shallow and deep aquifer of the study area possess good . Geophysical Studies shows that the area bears a good groundwater potential for both shallow and deep aquifer. The deeper aquifers are recharged by the inflow of Narayani River and deep seepage losses by sedimentary rocks in Siwalik Region and shallow aquifers are recharged by annual precipitation.
Hydrogeological Study in Mid-Western Part Deukhari Dun Valley of Satbaria Region Dang District Mid Western Nepal
(Department of Geology, 2013) Singh, Uttam Raj
Not available
Landslide Susceptibility Mapping of the Ghurmi-Dhad Khola Area in Eastern Nepal Using Gis
(Department of Geology, 2011) Bijukchhen, Subeg Man
The present study focuses on preparation of landslide susceptibility maps of the Ghurmi-Dhad Khola area, eastern Nepal using Geographic Information System (GIS). The study area consists of 77 landslides covering an area of 2.069 km2. The parameters considered for the study are geology, distance from faults and folds, distance from drainage, rock and soil type, land cover, slope aspect, slope angle and altitude. The detailed geological map of the study area was prepared along with other thematic maps for the susceptibility analysis. The methods followed for the susceptibility analysis were the heuristic and bivariate methods. In heuristic method, index-based approach was used to assess the landslide susceptibility. According to the map, an area of 24.77% falls under the high susceptibility zone whereas 18.92% of area falls under medium susceptibility and 56.31% in the low susceptibility zone. In landslide susceptibility assessment carried out using the statistical-index approach of bivariate analysis method, 28.03% of area is considered high susceptible for landslides and 21.08% of area falls under medium susceptibility zone. An area of 50.89% lies in the safe zone i.e. the low susceptibility zone. The two susceptibility maps were identical and success rate of both the maps were above 80%. Similarly there was 80.19% agreement between the two landslide susceptibility maps prepared by two different methods.
Litho-Biostratigraphy of Siwalik Sediments in Arun Khola Area in Nawalparasi and Palpa Districts, Western Nepal.
(Department of Geology, 2014) Lamichhane, Yubaraj
The study area located in the Nawalparasi and Palpa District of Western Development Region of Nepal. The toposheet No 099-11, 099-12, 099-15 and 099-16 cover whole section of the study area. Geographically the study area extends from longitude 83 0 47’50”E to 83 0 58’11”E and latitude from 27 0 40’2”N to 27 0 44’55”N. The total area covered is 163 sq Km. This desertation is concerned with the lithological and biological study of the mentioned area. This area is lies in the Siwalik Group of the Nepal Himalaya. The lithology of that area is like as the other parts of the Nepal but the naming are in different aspect. The study area covers the detail study of the rock unit between the CCT and MBT. Lithilogically the area is classified as Arung Khola Formation, Binai Khola Formation, Chitwan Formation and Deorali Formation. The Arung Khola and Binai Khola Formation are further divided into three members as Lower, Middle, Upper respectively. In these rock units the grain size is of the formation are increasing from older to younger units. Study of thin section of various location shows that the sandstone is of the arkose, lithic arenite and feldspathic types. The climate of the Siwalik formations is sub humid to humid. Palynologcal study is main parts of this thesis. Many pollen samples prepared and analysis has been done. Altogether 22 taxa belonging to 14 families of plant are documented from the Arung Khola Formation. The Arung Khola Formation is deposited in shallow water depositional basin. These texa are warm loving. Plam are common in the studied sample sho the tropical to sub tropical climate. These pollen represent the age of Late Miocene to early playstocene and climate as sa humid and warm as experienced in Terai area of Nepal today. Geological map, cross-section, columnar section, thin section preparation, pollen sample preparation, Paleocurrent analysis were done during the lab work and disertation preparation time. The paleo current flow from the pebble imbrication is found as S56 0 W around the Khani Damar Area.
Morphotectonic and Paleoseismological Study around the Charnath Khola Area, Central Nepal
(Department of Geology, 2012) Shiwakoti, Indira
Not available
River Dynamics and Restoration Design of the Nakhu Khola
(Department of Geology, 2010) Maharjan, Binod
Available with full text
Role of Geological Structures and Clay Minerals in the Occurrence of Landslides Along Mugling- Narayanghat Highway Section
(Department of Geology, 2010) Neupane, Bhupati
Each year Mugling-Narayanghat Highway section suffers from numerous landslides and debris flow. Geological structures and clay mineral content in soils have been investigated to understand their roles in the occurrence of landslides along Mugling- Narayanghat Highway section. In this section 13 large landslides in the Lesser Himalaya and the Siwaliks were investigated in detail and mapped to prepare landslide distribution map. From the landslides 11 soil samples were collected in the field, sieved and the finer fraction was subjected to X-ray diffraction analysis. X-ray analysis reveals that illite, chlorite and kaolinite were the main clay mineral in the soil. The main finding of the study is that in addition to the role of geology, geological structures and human activities, clay mineral content, particularly Illite, has significant role for the observed activity of the landslides in the study area.

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