Morpho-hydrologic parameters and classification of the Kodku River for stream stability assessment, southern Kathmandu, Central Nepal (original) (raw)
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The Kodku River is a fifth order wadeable stream, extending for 16.12 km in the Kathmandu intermontane basin, with about mainly alluvial and subordinately bedrock channel, and is a potential corridor that would link the southern remote areas of Kathmandu to the inner urban areas. The broad level morpho-hydrologic parameters, river classification, and streambank erosion potential were assessed for streambank stability condition. The river has sinuous (K=1.2) to highly meandering (K=1.7) pattern. Meander wavelength (L m) and meander belt width (W blt) increase with increasing stream order. Based on valley type, channel pattern and channel slope (Level I classification), the stream segments have been classified as 'B' type, 'C' type and 'Aa+' type streams. Width/depth (W/D) ratio (10.5 and 29.5) is generally high. Stream segments have moderate to low entrenchment as Entrenchment Ratio exceeds 1.6. Based on the bed material load, the Kodku River is a gravelly mix...
Bulletin of the Department of Geology, 1970
Five representative segments of the river were surveyed in detail for evaluating its dynamics and stability condition. The first (downstream) to the fifth (upstream) segments are classified as 'F4', 'C4', 'C4', 'B4' and 'B4' streams characterised by gravelly substrates. All these streams are competent enough to transport their bed material (d 90) as shown by the exceeding dimensionless shear stress over critical dimensionless shear stress of the river segments. The existing depth and slope of the river is far enough to carry d 90 of the substrate grain size. Stream power of segments 1 to 5 are respectively, 622.6, 79.0, 146.6, 354.6 and 15617.0 KN/s. The 'B4' streams show greater stream power, i.e., transport capacity compared to 'F4' followed by 'C4' streams. Therefore, the 'B4 streams (3rd and 4th order streams) are potential to degradation, and the 'C4' and 'F4' (both 5th order) streams are potential to aggradation depending on river morphology and dynamics. Meander geometry of the Manahara River exhibit deviation of variables (meander wavelength vs channel width, and meander belt width vs channel width) from the stability, suggesting existence of instability to some extent in the river.
ijetrm journal, 2022
The Pantale Khola and the Thado Khola both are the fourth order streams originating from the Churia Hills and flowing on the gravelly terrain towards the north and ultimately mixing to the Rapati Nadi. The total area of the study area is 64 km 2. The fluvial condition of these streams originating from the Churia Hills along with their characteristics, sediment transport and sediment dynamics were studied. Geomorphic characterization of both the streams were accomplished using the help of topographic maps and satellite imageries. Five stream transects on each of the stream were surveyed for cross-sections and longitudinal profiles. Samples were collected from the thalweg of each transect for suspended sediment concentration and Wolman's pebble counting method was applied for establishing grain size distribution. The Rosgen classification of streams was applied to classify the stream reaches. Manning's roughness coefficient was calculated on the features as seen on the field and hence discharge was calculated. The streams have been classified as F4 type for the Pantale Khola and F4, F4b types for the Thado Khola. The bed load was calculated and hence total sediment load was also calculated. Both the streams show the eroding potential as found out from the stream power.
Basinal and planform characteristics of the Kodku and the Godavari Rivers, Kathmandu, Central Nepal
Bulletin of the Department of Geology, 2013
The rivers of the Kathmandu Basin are vulnerable to flash floods and disturbances caused by anthropogenic as well as climatic changes. Two southern tributaries of the Bagmati River: the Kodku and the Godavari Rivers, have been considered for their (i) watershed-scale geomorphic parameters such as relative relief, drainage texture and stream order, (ii) stretchscale planform parameters such as sinuosity (K), meander belt width (Wblt), meander wavelength (Lm) and radius of curvature (Rc), and (ii) longitudinal profiles and slopes. Both Kodku and the Godavari Rivers are elongate basins with wide ranges of the watershed-scale parameters. The Godavari River is longer, larger and more sinuous compared to the Kodku River. The development of the patterns of the fifth order main stem stretches of both rivers with respect to the stream slopes, and asymmetric patterns of the meander loops indicate anomalous growth of the river stretches. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7414 Bulletin o...
Earth is a dynamic evolving system in surface. There are many cyclic processes acting on the surface of the earth. Even earth acts as a system. Fluvial process is one of the most powerful and dynamic agents of geomorphic agents. The fluvial landforms are very apparent compare to other agents such as wind, underground water, glacier and sea. Fluvial processes change rapidly when the earth landscape compared to other geomorphological processes. These processes are dynamic in nature due to natural phenomenon and human interference. This paper focuses on discussing fluvial processes and landforms of the Sai River. The paper also describes how the landforms of non-glacial rivers differ from the landforms of glacial rivers. A large number of the Himalayan watersheds which are densely populated are drained by the network of non-glacial fed rivers, due to anthropogenically accelerated climate change, the tributary rivers of these non-glacial watersheds are dying and their master rivers are dwindling steadily causing socioeconomic and environmental disruption in the region imposing a threat on the sustenance of mountain biodiversity, ecosystems and human civilization (Rawat et. al., 2020). The Sai is non-glacial fed river whose water level is decreasing every year. Therefore, the study focuses on the types of landforms created by the Sai River. The study analyses the identification and examination of river landforms with the help of GPS location and GIS maps. The river affects in three ways: Erosion, Transportation and Deposition. They are interrelated by vertical and horizontal erosion. In Present, fluvial processes and landforms of the Sai River have more impact by human activities such as channel modification, construction of dam, cannel, road, artificial levees. In the watershed area, the population lives parallel to the river. It is more useful for humans for agriculture, irrigation, water resources and fertile soil.
Rivers not only represent a vital resource for human activity but they are central to an understanding of geomorphology of most regions. A section of the river Subarnarekha (near Gopiballavpur) is considered for the study on bed and bank morphology associated with patterns of process and channel adjustment. The process-based study of alluvial channel has emphasized an alternative and smaller time and space scale for understanding alluvial channel dynamics. The sand-bed of river tract is complicated by the effects of significantly changing bed forms. However, the gravel bed of the river is lying below the depth of 1 meter from the top of the point bar sand bed which is often not mobile until discharges approach bank-full stage. The bank morphology reveals flood signatures of past events. The depositional activity of over bank flow on the floodplain is very different among the riverine system. The class of extreme events determines channel capacity, affecting channel pattern and more frequent events, although at times widely separated in time, controlled bed load movement and bed form adjustment. Variation of grain size is recorded from the outer bank to inner bank at the meandered section of Subarnarekha. Sand splays are significant feature on the over bank deposits particularly at the section of meandered banks. Bank margin cliffs are found on the older depositional bars at the curvature of the channel. All these modification of channel floor and channel bank are product of bank full discharge in the occurrences of floods. Repeated field survey, sediment grain size analysis, measurement of geomorphic features, satellite image analysis and analysis of discharge data reveal the above features of dynamic alluvial channel.
In the present research work, an attempt has been made to study the plan view of Tulsi and Bhogawati River. The study area forms a part of Tulsi channel from its dam to its confluence near Bid and a channel of Bhogawati from Radhanagari Dam to Prayag Chikhali of Kolhapur District. Channel in plan means, the various channel patterns of river i.e. straight, sinuous, meandering and braided. The study of river plan-form is significantly essential for river restoration and river conservation. Apart from hydrological events, unplanned agricultural activities and deforestation in the basin is extremely responsible in channel erosion and shifts in channel locations that is one of the causes for the variation in sinuosity index of the channel. River is generally controlled by geological characteristics of basin and its plan form, which equally influence on channel slope and shows the erosional or depositional signs of the river. Geomorphic characteristics and within channel variations are also influenced by the variability in river basin and its hydrology. The study of channel in section and channel in plan also predicts the future channel deposition and erosion. Therefore an attempt has been made to study the channel patterns and channel variability of Tulsi and Bhogawati River.