Faculty Publications
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Item Utility of Landsat Data for Assessing Mangrove Degradation in Muthupet Lagoon, South India(Elsevier, 2018) Subbarayan, S.; Jegankumar, R.; Selvaraj, A.; Jacinth Jennifer, J.; Kulithalai Shiyam Sundar, K.S.S.Mangrove swamps and forests are an essential interface of the coastal zone that provide various ecological and economic services contributing to coastal protection and carbon credits. The ever-changing land use along the coastal tract, especially saltpans and agricultural activities in the mangrove habitats, contribute to the reduction of mangrove swamp sprawl and degrade the mangrove forest. Remote sensing techniques are routinely used to provide spatial-temporal information on mangrove ecosystem distribution, species identification, health status, and population. By adopting supervised classification techniques using the capabilities of indices such as the Normalized Difference Water Index (NDWI) and the Normalized Difference Vegetation Index (NDVI), we attempt to map the spatio-temporal variations of the Muthupet Lagoon regions. The increase of land use changes in the vicinity of the Muthupet Lagoon drastically decrease the freshwater flow and create significant impacts on the mangrove habitat. The study described herein documented degradation of 40.3. ha of dense mangroves from 2013 to 2016, 135.5. ha from 2008 to 2013, and 166. ha from 1999 to 2008 due to high salinity, coastal erosion, and the intrusion of saltpans, aquaculture farmlands, and other human activities. The area of sparse mangroves increased by 38.2. ha between 2013 and 2016, by 42.7. ha from 2008 to 2013, and by 191.3. ha from 1999 to 2008 due to prominent restoration activities. © 2019 Elsevier Inc. All rights reserved.Item Monitoring Spatial and Temporal Scales of Shoreline Changes in the Cuddalore Region, India(Elsevier, 2018) Subbarayan, S.; Kulithalai Shiyam Sundar, K.S.S.; Vishnuprasath, S.R.Coastal zones are constantly undergoing changes in shape and environment due to natural processes and anthropogenic interventions. The study of shoreline change has become a matter of great concern in recent years. The measurement of shorelines is a key factor in coastal zone construction. A shoreline change study was carried out for a 33-km stretch of the Cuddalore coast between Gadilam and the Vellar River. Satellite images (2000, 2005, 2010, and 2015) were taken as an input dataset in a GIS platform. Automatic shoreline delineation was attempted by a masking technique using ENVI software. In this study, the modification of normalized difference water index (MNDWI) method extracted the raster shoreline-based contrast value of coastal pixels and thresholding techniques for segmenting water and land regions. DSAS software and reference digitized shoreline boundary data were used for the analysis of shoreline changes. End point rate (EPR) and net shoreline movement determination showed the northern part of the Uppanar River mouth under erosion (region A to C and E) and sediment deposition at an accretion rate of 7.6. m/year from EPR and 114. m from NSM. The maximum shoreline erosion rate was -. 3.8. m/year from EPR and -. 57. m from NSM. From these attempts and results, a methodical approach for detection and monitoring of shoreline changes on spatial and temporal scales of interest have been suggested. © 2019 Elsevier Inc. All rights reserved.Item Assessing Coastal Aquifer to Seawater Intrusion: Application of the GALDIT Method to the Cuddalore Aquifer, India(Elsevier, 2018) Subbarayan, S.; Kulithalai Shiyam Sundar, K.S.S.; Sivaranjani, S.Similar to many other parts of the world, water demand has been increasing in coastal areas due to industrial development, urbanization, population growth, agriculture, and tourism. As these demands are met from groundwater, the underground aquifers show rapidly increasing trends of depletion concomitant with seawater intrusion (SWI), which in turn is becoming a major environmental issue. In this chapter, vulnerability to seawater intrusion in the Cuddalore coastal aquifer is assessed by using the GALDIT method. This ranking- and weight-driven approach, based on various aquifer characteristics of the region, helped to determine the level of salt water intrusion in each distinct hydrological setting. Results of the study have shown that the area near the coast has been highly affected by SWI. Higher SWI in industrialized and urbanized areas is observed, suggestive of anthropogenically enhanced vulnerability. About 9.97% of the study area falls into the high vulnerability region, and the very low vulnerability region comprises 22.03% of the study. © 2019 Elsevier Inc. All rights reserved.Item Assessing Coastal Aquifer to Seawater Intrusion: Application of the GALDIT Method to the Cuddalore Aquifer, India(Elsevier, 2019) Subbarayan, S.; Kulithalai Shiyam Sundar, K.S.S.; Sivaranjani, S.Similar to many other parts of the world, water demand has been increasing in coastal areas due to industrial development, urbanization, population growth, agriculture, and tourism. As these demands are met from groundwater, the underground aquifers show rapidly increasing trends of depletion concomitant with seawater intrusion (SWI), which in turn is becoming a major environmental issue. In this chapter, vulnerability to seawater intrusion in the Cuddalore coastal aquifer is assessed by using the GALDIT method. This ranking- and weight-driven approach, based on various aquifer characteristics of the region, helped to determine the level of salt water intrusion in each distinct hydrological setting. Results of the study have shown that the area near the coast has been highly affected by SWI. Higher SWI in industrialized and urbanized areas is observed, suggestive of anthropogenically enhanced vulnerability. About 9.97% of the study area falls into the high vulnerability region, and the very low vulnerability region comprises 22.03% of the study. © 2019 Elsevier Inc. All rights reserved.Item Utility of Landsat Data for Assessing Mangrove Degradation in Muthupet Lagoon, South India(Elsevier, 2019) Subbarayan, S.; Jegankumar, R.; Selvaraj, A.; Jennifer, J.; Kulithalai Shiyam Sundar, K.S.S.Mangrove swamps and forests are an essential interface of the coastal zone that provide various ecological and economic services contributing to coastal protection and carbon credits. The ever-changing land use along the coastal tract, especially saltpans and agricultural activities in the mangrove habitats, contribute to the reduction of mangrove swamp sprawl and degrade the mangrove forest. Remote sensing techniques are routinely used to provide spatial-temporal information on mangrove ecosystem distribution, species identification, health status, and population. By adopting supervised classification techniques using the capabilities of indices such as the Normalized Difference Water Index (NDWI) and the Normalized Difference Vegetation Index (NDVI), we attempt to map the spatio-temporal variations of the Muthupet Lagoon regions. The increase of land use changes in the vicinity of the Muthupet Lagoon drastically decrease the freshwater flow and create significant impacts on the mangrove habitat. The study described herein documented degradation of 40.3ha of dense mangroves from 2013 to 2016, 135.5ha from 2008 to 2013, and 166ha from 1999 to 2008 due to high salinity, coastal erosion, and the intrusion of saltpans, aquaculture farmlands, and other human activities. The area of sparse mangroves increased by 38.2ha between 2013 and 2016, by 42.7ha from 2008 to 2013, and by 191.3ha from 1999 to 2008 due to prominent restoration activities. © 2019 Elsevier Inc. All rights reserved.Item Monitoring Spatial and Temporal Scales of Shoreline Changes in the Cuddalore Region, India(Elsevier, 2019) Subbarayan, S.; Kulithalai Shiyam Sundar, K.S.S.; Vishnuprasath, S.R.Coastal zones are constantly undergoing changes in shape and environment due to natural processes and anthropogenic interventions. The study of shoreline change has become a matter of great concern in recent years. The measurement of shorelines is a key factor in coastal zone construction. A shoreline change study was carried out for a 33-km stretch of the Cuddalore coast between Gadilam and the Vellar River. Satellite images (2000, 2005, 2010, and 2015) were taken as an input dataset in a GIS platform. Automatic shoreline delineation was attempted by a masking technique using ENVI software. In this study, the modification of normalized difference water index (MNDWI) method extracted the raster shoreline-based contrast value of coastal pixels and thresholding techniques for segmenting water and land regions. DSAS software and reference digitized shoreline boundary data were used for the analysis of shoreline changes. End point rate (EPR) and net shoreline movement determination showed the northern part of the Uppanar River mouth under erosion (region A to C and E) and sediment deposition at an accretion rate of 7.6m/year from EPR and 114m from NSM. The maximum shoreline erosion rate was −3.8m/year from EPR and −57m from NSM. From these attempts and results, a methodical approach for detection and monitoring of shoreline changes on spatial and temporal scales of interest have been suggested. © 2019 Elsevier Inc. All rights reserved.Item Assessing the impact of damage and government response toward the cyclone Gaja in Tamil Nadu, India(Elsevier, 2021) Devanantham, D.; Subbarayan, S.; Jennifer, J.J.; Kulithalai Shiyam Sundar, K.S.S.; Singh, L.; Sankriti, R.The cyclone is one of the most frequently occurring natural disaster in all tropical countries that interrupts the socioeconomic development. In India, the rate of cyclone occurrence has increased by almost 30%. Tamil Nadu state, India, becomes one of the most cyclone-prone regions in the country. Severe cyclonic storm Gaja made landfall on 16th November 2018 in Nagapattinam district in Tamil Nadu. It had sustained wind speeds of 100-110 km/h with gusts of up to 120 km/h. The storm brought a significant amount of rainfall of about 140-170 mm. According to the reports, 45 people lost their lives, and 76, 290 people were evacuated from low-lying areas and sheltered in 300 relief centers. In this study, we have discussed strategies on the response after the event, preparedness, relief, recovery operations, rehabilitation, reconstruction, violent conflicts, economic sustainability, infrastructure development, livelihood, and the cause for severe damage and resilience. © 2021 Elsevier Inc. All rights reserved.Item Assessing the impact of 2018 tropical rainfall and the consecutive flood-related damages for the state of Kerala, India(Elsevier, 2021) Kulithalai Shiyam Sundar, K.S.S.; Deka, P.C.; Subbarayan, S.; Devanantham, D.; Jacinth Jennifer, J.Flood is the relatively high flow in the river, markedly than the usual resulting in the inundation of low land. Usually, river floods when the river can no longer contain its discharge from its catchments. Flood is the costliest as well as a common natural disaster in the world devastating both life and economy to a greater extent. The state of Kerala has faced an unprecedented rainfall followed by severe floods in August 2018 with a death toll for 504. Kerala is the southernmost narrow strip of the coastal territory that slopes down the Western Ghats to reach the Arabian Sea with 14 districts in the state. According to the Central Water Commission (CWC), the state received 2346.6 mm of rain from June to 19th of August, which is 42% more than the average rainfall. The state received a tremendous rainfall of 758.6 mm in the first 20 days of August which is 164% more than the actual rainfall. With the heavy rainfall all over the state, floods prevailed by the end of July. Once again a massive spell of rainfall happened at 8th and 9th of August which led to further flooding in Wayanad district. Due to the continuous rainfall from the first week of June to August, water levels were almost near the Full Reservoir Level. So, the water was released from several dams due to the heavy rainfall in the catchment. Another intense spell of rainfall took place by the 14th of August and continued till 19th of August resulting in the massive flood throughout the state affecting 13 of the 14 districts leading to the evacuation of about 3.4 million people to the 12, 300 relief camp across the state making the worst flood in the century. 2018 Kerala flood caused extensive damage to the crops, building, and infrastructure; its associated aftermath of the flood resulted in a huge loss to its economic, social, and natural environment, accompanied by the 331 landslides across 10 districts. After ravaging by the flood, the state has faced communicable diseases leptospirosis, chicken pox, hepatitis A, malaria, and dengue resulting in a death toll for 180. Thus, this paper is tried to understand the impact of the tropical rainfall followed by the devastating flood that occurred in the state of Kerala in August 2018 and to understand the impact on the socioeconomic disturbances, its resilience aftermath the flood. © 2021 Elsevier Inc. All rights reserved.Item Mapping of Flood-Inundated Urban Regions Using Sentinel-1 SAR Imagery for the 2018 and 2019 Kerala Floods(Springer Science and Business Media Deutschland GmbH, 2023) Kulithalai Shiyam Sundar, K.S.S.; Kundapura, S.Floods are a common natural calamity causing an immense impact on the natural and human ecosystems around the world. A combination of unfavorable meteorological, hydrological, and physical conditions causes it. The study area is the Vembanad Lake System in Kerala, India comprising six watersheds: Periyar, Muvattupuzha, Meenachil, Manimala, Pamba, and Achenkovil that drains into the lake. The state faced severe flooding in 2018 and 2019 due to torrential rainfall. Thus, this study focuses on assessing flood inundation mapping utilizing Sentinel-1 SAR imagery in Google Earth Engine (GEE) for 2018 and 2019 since it simplifies and streamlines the complicated and time-consuming pre-processing of Sentinel-1 SAR images. These images are pre-processed, and the flooded areas are delineated. Change detection by image ratio method is utilized to identify the flood inundated and the most frequently flooded areas. The results show that 4% and 3.21% of the entire region were flooded in 2018 and 2019, respectively. In addition, 14.7 Km2 of the urban area flooded in 2018, whereas 7.26 Km2 of urban land flooded in the 2019 floods. Hence, these inundation maps can be utilized for risk assessment and primary preventive measures. It also serves as a tool to warn the residents in that region about the hazards and the possibility of inundations at the time of heavy downpours in the future. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Mapping of 2018 Flood and Estimation of Future Flood Inundation Region for Vembanad Lake System in Kerala, India Using Sentinel-1 SAR Imagery(Springer Science and Business Media Deutschland GmbH, 2024) Kulithalai Shiyam Sundar, K.S.S.; Kundapura, S.Floods have claimed the lives of countless people and caused significant property damage, jeopardizing their livelihoods. The study area is the Vembanad Lake System in Kerala, India has faced severe flooding in 2018 due to torrential rainfall. Considering that Google Earth Engine (GEE) streamlines and simplifies the complex and time-consuming pre-processing of SAR images, this paper evaluates flood inundation mapping using Sentinel-1 SAR data for 2018. The flood inundation zone for the study is calculated using the Land Use Land Cover (LULC) map for 2018 and the forecasted LULC for 2035 and 2050. Hence, the research assesses the areas affected by floods in 2018 and those that may experience flooding of a similar degree in the near future. Thus, the extent of flood inundation during the 2018 floods and the potential flood inundation region for future LULC in 2035 and 2050 are determined. From the analysis, 14.7 km2 of built-up area was inundated during the 2018 floods. The 2018 flood event is used to quantify the flood that may inundate the future LULC in 2035 and 2050; it is found that the flood will affect about 19.87 km2 and 23.32 km2 of the built-up region, respectively. According to the study, the built-up area impacted by the flooding will increase by 34.99% and 58.4% from 2018 to 2035 and 2050, respectively. Examining the flood-prone areas and potential flood-affected areas in the future will be of great use to planners in their efforts to forewarn of an impending tragedy. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.