Faculty Publications

Now showing 1 - 4 of 4

Geomorphological behaviour of Sasihithlu, Mangalore coast, west coast of India
(2011) Nagaraj, G.; Karjagi, A.; Kumar, M.; Dwarakish, G.S.
Beach geomorphological studies have been carried out with help of conventional methods and remote sensing techniques. Conventional methods include beach profile surveys and beachwidth measurements whereas remote sensing techniques involved in utilization of satellite images, digitization and analyses. Beach profile surveys and beachwidth measurements are carried out at monthly intervals over a period of one year (September 2009 to September 2010) to understand dynamics of sediment along the coastal segment of 7km at Sasihithlu, north off Mangalore coastline. Six locations are selected based on their significant site characteristics along the coastal segment. It is observed erosion with steeper slopes during the monsoon and simultaneously deposition with flat and wider exposed slopes during the fair weather season. But the more drastic and dramatic changes are observed in the vicinity of Mulki-Pavanje rivermouth, since the rivers Mulky and Pavanje bring any kind of sediments irrespective of seasons. Because of this the profiles alter dramatically in the vicinity of rivermouth. It is estimated that the Sasihithlu beach has experienced a net loss of about 2515m 3/m, a net gain of about 3525m 3/m and hence a gain of about 1010m 3/m sediments in an annual cycle. Addition to conventional methods, remote sensing analysis is also carried out to detect the influence of rivers and their flow on rivermouth system in recent decades (1988-2009) with the help of satellite images and GIS tools. It is observed that the shifting tendency of rivermouth either south or north irrespective of seasons. However a detailed investigation on shoreline pattern showed a clear indication of shifting shoreline towards south. Therefore present study suggests to construct coastal protection structures on either side of the rivermouth, through that the damage to the property could be minimized. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Seawalls: Performance and their failure analysis along Southern Karnataka, West Coast of India
(2012) Rao, S.; Hegde, A.V.; Dwarakish, G.S.; Janardhan, J.; Venkat Reddy, D.
Beach erosion is a major problem along the south west coast of India. The beach erosion particularly along the south Karnataka coast is due to, 1) direct attack of waves in an open coast, which might have been intensified in some areas due to wave refraction, 2) erosion at river mouths where one or two rivers together join the sea. The coastal protection works adopted along the South Karnataka coast are mainly the seawalls. However, some portions of these seawalls have been damaged either partially or fully. A critical study shows that these failures are due to the scouring at the toe structure. Scouring causes the failure of the seawall due to loss of support. A calculated risk may be taken to design the seawall without taking scour depth into account but provide for adequate maintenance in case scour occurs and partial failure of the seawall takes place. © 2012 Cafet-Innova Technical Society. All rights reserved.
Shoreline analysis using Landsat-8 satellite image
(Taylor and Francis Ltd., 2021) Yadav, A.; Dodamani, B.M.; Dwarakish, G.S.
The shoreline is a boundary between wet and dry part of the beach, and it is dynamic in nature. Natural and human factors are always influencing shoreline configuration. One of the important natural events which are responsible for the shoreline configuration along the Karnataka coast is southwest monsoon, and hence there is a change in shoreline position between pre- and post-monsoon. For the present research work, Karwar beach with two beaches, Rabindranath Tagore beach and Devabagh beach along Karnataka coast, West coast of India were selected as study area. Landsat-8 satellite images for the years 2013–2017 were used in the present study and processed for May and October of every year, using ERDAS imagine 2014 and ArcGIS 10.3 tools to generate shoreline configuration maps. Finally, the comparison was made between 2013 and 2017 years, and the results indicate that the Devbagh beach during pre-monsoon season has an average shoreline change rate of ?7.54 m/yr (EPR) and ?5.57 m/yr (LRR) and during post-monsoon season it is 0.34 m/yr (EPR) and ?0.46 m/yr (LRR). Similarly, Rabindranath Tagore beach during pre-monsoon seasons has an average shoreline change rate of 0.004 m/yr (EPR) and 1.67 m/yr (LRR), and in post-monsoon season, it is ?5.77 m/yr (EPR) and ?6.55 m/yr (LRR) respectively. The total uncertainty error was estimated and found to be (Formula presented.) 5.00 m/yr. © 2018 Indian Society for Hydraulics.
Effect of disturbed river sediment supply on shoreline configuration: A case study
(Taylor and Francis Ltd., 2022) Yadav, A.; Dodamani, B.M.; Dwarakish, G.S.
The magnitude of river sediment supply and its distribution play a significant role in coastal sediment dynamics, especially in erosion and deposition. Due to the construction of the dam, obstruction in the natural flow of water occurs, and part of the sediment is trapped. In the present study, the Kali river catchment and its river-mouth at Karwar, Devbagh, and Ravindranath Tagore beaches are considered as the study area, to assess the impact of dams on coastal processes. Landsat data for 42 years, from 1975 to 2017, were collected and analyzed using DSAS, an ArcGIS extension. The sediment yield estimated at the Kali river basin outlet, without the dam is 4.19 t/ha/yr and with the dam, it is estimated to be 1.42 t/ha/yr. Similarly, for the Aghanashini river basin outlet, the sediment yield was found to be 4.58 t/hr/yr. From the results of shoreline analysis, it is found that after the construction of the dam, Devbagh beach is under erosion at the rate of ?0.93 m/yr End Point Rate (EPR) and ?0.47 m/yr Linear Regression Rate (LRR). Ravindranath Tagore beach also has undergone erosion, which is ?0.75 m/yr (EPR) and ?0.97 m/yr (LRR). Further, both the beaches have been changed to the erosion zone. © 2021 Indian Society for Hydraulics.

Faculty Publications

Browse

Filters

Settings

Sort By

Results per page

Search Results