Faculty Publications
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Item In order to study sediment travelling paths across shoreline in different seasons, sediment samples were collected normal to the shoreline along three profiles, separated by 220m from Surathkal beach near Karnataka Regional Engineering College (K.R.E.C.), Karnataka. The sediments were analysed for their grain size characteristics (statistical parameters) and sediment trend matrix was prepared. By using sediment trend matrix, sediment travelling paths were drawn. It has been found that during premonsoon, sediments were moving predominantly towards offshore region, resulting in erosion. Sediments were moving predominantly towards shore and build-up of beach takes place during the post monsoon season.(Sediment trend matrix analysis along shore normal transects off Surathkal beach, Karnataka) Rao, S.; Shirlal, K.G.; Rao, N.B.S.2003Item Coastal vulnerability assessment of the future sea level rise in Udupi coastal zone of Karnataka state, west coast of India(2009) Dwarakish, G.S.; Vinay, S.A.; Natesan, U.; Asano, T.; Kakinuma, T.; Venkataramana, K.; Pai, B.J.; Babita, M.K.Udupi coast in Karnataka state, along the west coast of India, selected as a study area, is well known for sandy beaches, aquaculture ponds, lush greenery, temples and major and minor industries. It lies between 13°00?00?-13°45?00? north latitudes and 74°47?30?-74°30?00? east longitudes, the length of the coastline is 95 km, and is oriented along the NNW-SSE direction. It is vulnerable to accelerated sea level rise (SLR) due to its low topography and its high ecological and touristy value. The present study has been carried out with a view to calculate the coastal vulnerability index (CVI) to know the high and low vulnerable areas and area of inundation due to future SLR, and land loss due to coastal erosion. Both conventional and remotely sensed data were used and analysed through the modelling technique and by using ERDAS Imagine and geographical information system software. The rate of erosion was 0.6018 km2/yr during 2000-2006 and around 46 km of the total 95 km stretch is under critical erosion. Out of the 95 km stretch coastline, 59% is at very high risk, 7% high, 4% moderate and 30% in the low vulnerable category, due to SLR. Results of the inundation analysis indicate that 42.19 km2 and 372.08 km2 of the land area will be submerged by flooding at 1 m and 10 m inundation levels. The most severely affected sectors are expected to be the residential and recreational areas, agricultural land, and the natural ecosystem. As this coast is planned for future coastal developmental activities, measures such as building regulation, urban growth planning, development of an integrated coastal zone management, strict enforcement of the Coastal Regulation Zone (CRZ) Act 1991, monitoring of impacts and further research in this regard are recommended for the study area. © 2009 Elsevier Ltd. All rights reserved.Item Quantifying aquifer properties and freshwater resource in coastal barriers: A hydrogeophysical approach applied at Sasihithlu (Karnataka state, India)(2012) Vouillamoz, J.-M.; Hoareau, J.; Grammare, M.; Caron, D.; Nandagiri, L.; Legchenko, A.Many human communities living in coastal areas in Africa and Asia rely on thin freshwater lenses for their domestic supply. Population growth together with change in rainfall patterns and sea level will probably impact these vulnerable groundwater resources. Spatial knowledge of the aquifer properties and creation of a groundwater model are required for achieving a sustainable management of the resource. This paper presents a ready-to-use methodology for estimating the key aquifer properties and the freshwater resource based on the joint use of two non-invasive geophysical tools together with common hydrological measurements.
We applied the proposed methodology in an unconfined aquifer of a coastal sandy barrier in South-Western India. We jointly used magnetic resonance and transient electromagnetic soundings and we monitored rainfall, groundwater level and groundwater electrical conductivity. The combined interpretation of geophysical and hydrological results allowed estimating the aquifer properties and mapping the freshwater lens. Depending on the location and season, we estimate the freshwater reserve to range between 400 and 700 L m??'2 of surface area (A± 50%). We also estimate the recharge using time lapse geophysical measurements with hydrological monitoring. After a rainy event close to 100% of the rain is reaching the water table, but the net recharge at the end of the monsoon is less than 10% of the rain. Thus, we conclude that a change in rainfall patterns will probably not impact the groundwater resource since most of the rain water recharging the aquifer is flowing towards the sea and the river. However, a change in sea level will impact both the groundwater reserve and net recharge. © Author(s) 2012.Item Study on soil moisture retention function for the indian forested hillslope soils(Taiwan Geotechnical Society 43, Sec. 4, Keelong Rd, Taipei 106,, 2013) Prasanna, P.; Varija, K.; Kumar, P.Pedotransfer functions (PTFs) are one of the widely used tools to predict the soil water retention curves (SWRC). The objective of this study was to develop and validate point and parametric PTF models based on nonlinear regression technique using the different set of predictors such as particle-size distribution, bulk density, porosity and organic matter content. Soil samples were collected from different elevations at different depths in forested hillslope area of Pavanje river basin that lies in coastal area of Karnataka, India. The point PTF models estimated retention points at 33, 100, 300, 500, 1000, and 1500 kPa pressure heads and the parametric PTF models estimated the van Genuchten and Brooks-Corey retention parameters. The data were evaluated with the root mean square error (RMSE), mean error (ME), and coefficient of determination (R2) between the measured and predicted water contents. The prediction of soil water retention curve using PTFs by point estimation method for the sampled soils was relatively successful (best case R2 = 0.862). Further, a critical comparative analysis on the performances of point and parametric methods was done. It can be suggested to use the developed PTFs for the prediction of soil water retention curve for the loamy sand and sandy loam textured soils in this forest area of the coastal region in south western portion of India.Item Land use/land cover changes around Rameshwaram Island, east coast of India(National Institute of Science Communication and Policy Research, 2014) Gowthaman, R.; Dwarakish, G.S.; Sanilkumar, V.Land-use/land cover changes are studied using the Indian Remote Sensing satellite (IRS-1C, IRS-P6) Linear Image Self-scan Sensor (LISS) III data of 1998 and 2010. Coastal land use categories such as sand, vegetation, coral reef and water have been identified using interpretation keys. Results of land-use/land cover assessment based on visual interpretation are presented. The study indicates water body of 178 and 177 km2, sand features of 32 and 32 km2, vegetation of 28 and 35 km2 and coral reef of 5 and 6 km2 respectively. © 2014, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.Item Spatio-temporal precipitation variability over Western Ghats and Coastal region of Karnataka, envisaged using high resolution observed gridded data(Springer Science and Business Media Deutschland GmbH, 2017) Doranalu Chandrashekar, V.; Shetty, A.; Singh, B.B.; Sharma, S.Climatic changes in the recent decades have led to large variations in precipitation over the different geographical regions of the globe. Changes in precipitation pattern over the space and time can severely affect the country like India, which has a large spatio-temporal variability in the precipitation. Any shift in the mean precipitation pattern pose a challenge to economy, agricultural farming and the ecosystem of these regions. In the present study, we analyze the seasonal spatio-temporal variation in trends of long term (1901–2013) observed high resolution (0.25° × 0.25°) gridded daily precipitation data of the Indian Meteorological Department over Western Ghats and coastal region of Karnataka, vulnerable to the risks of climate change. Our analysis shows increasing trend in seasonal ratio of precipitation over the Southern coastal plains and the adjacent Western Ghats region during pre-monsoon (MAM) while the southern coastal plains show decreasing trend in monsoon period (JJAS). Daily intensity index of precipitation during monsoon shows increasing trend in northern plains with decreasing trend in the medium precipitation events. Our study finds that different topographic regions of Karnataka have different responses in the trends of precipitation, particularly the response of plains is quite different to that of the higher elevated Ghat region. © 2017, Springer International Publishing AG, part of Springer Nature.Item Trends in extreme rainfall over ecologically sensitive Western Ghats and coastal regions of Karnataka: an observational assessment(Springer Verlag service@springer.de, 2018) Chandrashekar, V.D.; Shetty, A.Rainfall is one of the pivotal climatic variables, which influence spatio-temporal patterns of water availability. In this study, we have attempted to understand the interannual long-term trend analysis of the daily rainfall events of ? 2.5 mm and rainfall events of extreme threshold, over the Western Ghats and coastal region of Karnataka. High spatial resolution (0.25° × 0.25°) daily gridded rainfall data set of Indian Meteorological Department was used for this study. Thirty-eight grid points in the study area was selected to analyze the daily precipitation for 113 years (1901–2013). Grid points were divided into two zones: low land (exposed to the sea and low elevated area/coastal region) and high land (interior from the sea and high elevated area/Western Ghats). The indices were selected from the list of climate change indices recommended by ETCCDI and are based on annual rainfall total (RR), yearly 1-day maximum rainfall, consecutive wet days (? 2.5 mm), Simple Daily Intensity Index (SDII), annual frequency of very heavy rainfall (? 100 mm), frequency of very heavy rainfall (? 65–100 mm), moderate rainfall (? 2.5–65 mm), frequency of medium rainfall (? 40–65 mm), and frequency of low rainfall (? 20–40 mm). Mann-Kendall test was applied to the nine rainfall indices, and Theil-Sen estimator perceived the nature and the magnitude of slope in rainfall indices. The results show contrasting trends in the extreme rainfall indices in low land and high land regions. The changes in daily rainfall events in the low land region primarily indicate statistically significant positive trends in the annual total rainfall, yearly 1-day maximum rainfall, SDII, frequency of very heavy rainfall, and heavy rainfall as well as medium rainfall events. Furthermore, the overall annual rainfall strongly correlated with all the rainfall indices in both regions, especially with indices that represent heavy rainfall events which is responsible for the total increase of rainfall. © 2018, Saudi Society for Geosciences.Item Prediction of wind-wave climate along Karnataka coast(Springer, 2021) Upadhyaya, K.S.; Rao, S.; Rao, M.Karnataka is a coastal state on the west coast of India along the Arabian Sea. The coast experiences a harsh wave climate during the southwest monsoons. Most of the coast is facing problems due to coastal erosion. Hence, in the present study, a numerical model has been set up using MIKE 21 Spectral Wave (SW) module to predict the wave climate. The wave climate along the Indian domain is simulated by wind speed datasets from Global Climate Model (GCM). Wind speed datasets from ERA-Interim is initially validated against in-situ measurement which had a correlation of 0.93. A hindcast study spanning 26 years based on 38 GCMs from different modelling institutes was performed. A comparison of wind speed datasets showed CMCC-CM RCP 4.5 wind projections were closer to ERA-Interim reanalyzed dataset and was used to predict the wave climate. The performance of the MIKE numerical model driven by CMCC-CM RCP 4.5 wind fields showed a correlation greater than 0.7 when validated against in-situ measurement. The numerical model simulations driven by wind speeds from CMCC-CM RCP 4.5 up to the year 2070 showed a gradual increase in the significant wave height which is indicative of the effects of climate change on the wave climate along the Karnataka coast. The projected significant wave height for 2070, when compared with the present wave climate, indicated an increase in the range of 10–21% at the six locations. The predicted wave pattern based on numerical simulations indicated a shift in the peak values in the monsoon month of June along the coast. The predicted wave parameters with a 10-year return period can be used for the design of coastal structures along the Karnataka coast. © 2021, Indian Academy of Sciences.Item Assessment of Bi-Decadal Groundwater Fluctuations in a Coastal Region Using Innovative Trends and Singular Spectrum Analysis(Springer, 2023) Krishnan, C.; Mahesha, A.Coastal areas are among the densely populated regions in the world with growing population and subsequent increasing demands for water. Understanding the long-term variations in available water resources aids in efficient water conservation, management and allocation strategies. The present study investigated the long-term trends in groundwater depths (GWDs) for pre-monsoon and post-monsoon seasons in the coastal district of Kollam during the period 1996∼2017, where groundwater is the primary source for domestic and agricultural uses during summer season. The trends examined using the modified Mann Kendall (mMK), innovative trend analysis (ITA) and Sen’s slope estimator indicated a decreasing pre-monsoon GWD trends at an average of −0.5m/decade in 63% of the wells, while increasing post-monsoon GWD trends at an average rate of +0.43m/decade in 72% of the wells at 5% significance level. The singular spectrum analysis (SSA) captured monotonic as well as non-monotonic trend trajectories for the GWDs. About 41% wells exhibited a correlation below — 0.5 (p<0.05) between post-monsoon GWDs and JJASO (June, July, August, September and October) rainfall totals. The increasing post-monsoon GWDs could be related to recent changes in the southwest monsoon patterns over the peninsular India. Adequate planning and management of existing water resources could impart better control on water conservation strategies under the scenario of climate change. © 2023, Geological Society of India, Bengaluru, India.Item Coastal vulnerability assessment for the coast of Tamil Nadu, India—a geospatial approach(Springer Science and Business Media Deutschland GmbH, 2023) Devanantham, D.; Subbarayan, S.; Kulithalai Shiyam Sundar, P.A coastal region is a section of land that borders a significant body of water, often the sea or ocean. Despite their productivity, they are sensitive to even little alterations in the outside environment. This study aims to develop a spatial coastal vulnerability index (CVI) map for the Tamil Nadu coast of India, which has diverse coastal and marine environments that are ecologically fragile zones. Climate change is expected to increase the intensity and frequency of severe coastal hazards, such as rising sea levels, cyclones, storm surges, tsunamis, erosion, and accretion, severely impacting local environmental and socio-economic conditions. This research employed expert knowledge, weights, and scores from the analytical hierarchy process (AHP) to create vulnerability maps. The process includes the integration of various parameters such as geomorphology, Land use and land cover (LULC), significant wave height (SWH), rate of sea level rise (SLR), shoreline change (SLC), bathymetry, elevation, and coastal inundation. Based on the results, the very low, low, and moderate vulnerability regions comprise 17.26%, 30.77%, and 23.46%, respectively, whereas the high and very high vulnerability regions comprise 18.20% and 10.28%, respectively. The several locations tend to be high and very high due to land-use patterns and coastal structures, but very few are contributed by geomorphological features. The results are validated by conducting a field survey in a few locations along the coast. Thus, this study establishes a framework for decision-makers to implement climate change adaptation and mitigation actions in coastal zones. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.