R. Sivakumar

Comparison of in-Situ Hyperspectral and Landsat ETM+ Data for Chlorophyll-a Mapping in Case-II Water (Krishnarajapuram Lake, Bangalore)

Water quality of inland water bodies is most important for humankind as it has direct impact on health, environment, agriculture etc. Estimation of chlorophyll-a (Chl-a) content provides phytoplankton concentration, a measure of water quality. The estimation of Chl-a using laboratory method consumes chemicals and takes long time. On the other hand, spectral reflectance methods viz. in-situ hyperspectral spectroradiometer measurements and satellite remote sensing are less expensive and provide results faster. The laboratory and spectroradiometer methods require somebody to sail into the lake to collect samples or measure the spectral reflectance, whereas the satellite remote sensing collects data from space, provides more samples and synoptic coverage. The aim of this study is to estimate the chlorophyll-a concentration using in-situ hyperspectral spectroradiometer data and Landsat-7 Enhanced Thematic Mapper (ETM+) data, compare the results and map chlorophyll concentration of the lake with suitable data. The relation between band reflectance ratios and measured values of Chl-a was established using regression analysis. That relation was used to map the Chl-a concentration of the lake. It was found that spectroradiometer data provided better correlation with measured values of Chl-a than Multispectral data. As satellite data provide full coverage, mapping of Chl-a concentration of lake was done with it.

Evaluation of physical and morphometric parameters for water resource management in Gad Watershed, Western Ghats, India: an integrated geoinformatics approach

The selected study area is a coastal watershed which receives high rainfall in the monsoon season. During this period, most of the water input to the watershed drains to the Arabian Sea without any adequate use due to the rugged topography of the watershed. Hence, an attempt has been made to assess the physical properties specifically morphometric parameters of the Gad watershed using geoinformatics techniques along with field evidence for understanding the relationship between fluvial landforms and hydro-physical parameters in the region. Morphometric parameters have been analyzed and integrated with physical parameters like topography, rainfall, soil, land use–land cover, geology, and geomorphology for evaluating the potential water resource availability in the Gad watershed. The results of the study have shown that there is high surface water availability in the watershed with very low water retaining capacity, mainly in the upper region of the watershed due to presence of basaltic bedrock and steep slopes. Based on this work, a water resource management plan has been suggested at a subwatershed level which established on the physical properties and morphological characteristics of the study area.

Assessment of morphometric parameters for the development of Relative Active Tectonic Index and its significant for seismic hazard study: an integrated geoinformatic approach

Earthquake is a geological natural hazard which is shaking of earth’s surface due to seismic activity. The Himalayan region and quaternary geological surface of Indian sub-continent had experienced several earthquakes in the recent geological period due to reactivation of existing faults. Surface drainage system and its morphometric characteristics are controlled by subsurface geo-structural features and active tectonic process which have greater impact on seismic activity. Thus, the present study focuses on the analysis of morphometric parameters for the development of Relative Active Tectonic Index (RATI) and its significant for seismic hazard assessment using geoinformatics. The different morphometric parameters have been analyzed and geospatial databases have been generated. The RATI has been estimated by considering higher priority tectonic influencing parameters based on Principal Component Analysis (PCA) methods and the output has also been integrated with thematic and seismological databases to understand its significance for seismotectonic activity. The result shows that the very high and high Relative Active Tectonic Index are observed in greater and lesser Himalayan sequence, where frequency of earthquake and its magnitudes are also high. The anomalous nature of drainage network, compressed meander in youthful stage, presence of high resistance rocks, structural control on drainage network, relief steepness, and v-shaped narrow valley are the indicator of active tectonics and seismic activity in this region. Even though the foothills micro-basin shows moderate or low Relative Active Tectonic Index, morphometric analysis depicts that it is highly elongated in nature with significant surface tilt and have a greater influence of tectonic deformation. In addition, the continuous stress from Main Frontal Thrust has a significant role for the landscape upliftment and seismic activity in this region. The micro-basin which is located in the quaternary alluvial surface, has not produced any major earthquake in the past, but has greater influence on tectonic activity and may produce earthquake in the future.

Quantification of Geomorphic Indices for Identifying Water Retaining Problem in Basaltic Terrain and Preparation of Water Resource Management Plan Through Integrated Remote Sensing and GIS Techniques

Water is an essential resource for the existence of life on earth. The storage capacity of the water depends on the physiography, soil, slope and geomorphic characteristics of the region. The analysis of geomorphic indices can signify the relationship between topographic characteristic and water retaining capacity which helps in identifying the water shortage problem and its solution. Most of the coastal watersheds in Deccan trap region in India face water scarcity problem during non-monsoonal season as they are covered mostly by basaltic hard rock terrain which is less porous in nature. The main focus of the present research is the analysis of geomorphic indices to address the water retaining problem and to suggest water resource management plan through integrated Remote Sensing and GIS techniques. To achieve this goal, the spatial data has been collected from different sources which is incorporated with field observation data. The thematic databases such as geology and geomorphology have been prepared to understand the topographical characteristic of the study area. The various geomorphic indices have been quantified with the help of satellite image and ASTER GDEM in GIS platform. The comparative geomorphic indices curves have been prepared to understand the topographic and geomorphic factors for addressing the water recharge problems. The analysis of geomorphic indices shows that the water retaining capacity is very low in the Upper gad and Janvali sub-watershed due to the influence of hard (Basaltic) rock, steep slope and has greater structural control. Further, hard rock terrain, rugged topography and surface roughness have been observed during field study which has great influence on water retaining capacity. The suitable artificial recharge techniques have also been suggested for sustainable development of water resource in the study area.

Identification of Geomorphic Anomaly and Morphotectonic Signature to Study the Seismotectonic Activity and Its Impact on Infrastructure Development Through Integrated Remote Sensing and GIS Techniques

The anomalous nature of basin morphological characteristics produces significant geomorphic anomaly which is the indicator of seismotectonic activity. In recent years, the increasing frequency of earthquakes and subsequent damages to infrastructures in Indian sub-continent reveal to study the seimotectonic earthquake. Hence, the present research focuses to identify the geomorphic anomaly and morphotectonic signature to study the seismotectonic activity and its impact on infrastructure development through integrated remote sensing and GIS techniques. The various geomorphic indices have been computed and superimposed curves have been analysed to identify the geomorphic anomaly. Also, the morphotectonic features have been recognized by analysing satellite images and field observation data to find out the active tectonic signature. Finally geomorphic anomaly and morphotectonic signature have been integrated to study the seismotectonic activity and compared with existing infrastructures to understand its seismic vulnerability. The analysis reveals that the neotectonic deformations, drainage anomaly, elongated basin, tilted surface and structural influence are the major geomorphic anomaly and significant evidences for seismotectonic activity in the study region. The various morphotectonic signatures such as narrow valley, knick point, alluvial terraces, triangular facets, river meander in resistance surface and uplifted topography are the great signatures of seismotectonic activity. The various infrastructures such as heritage, educational, private, administrative, residential buildings, communication bridges and roads have been developed in various towns which are associated with significant geomorphic anomaly and morphotectonic features are more vulnerable during seismic activity. Also, the seismic retrofitting techniques have been suggested for existing infrastructures to protect them during seismic activity.

Earthquake hazard assessment through geospatial model and development of EaHaAsTo tool for visualization: an integrated geological and geoinformatics approach

An earthquake is a natural phenomenon which is very frequent in Himalayan region in India. In southern peninsula India, the spatial occurrence of earthquake is irregular, whereas the northeastern, the north and the northwestern Himalayan parts of India are subjected to regular occurrences of earthquakes as they mark the boundary of the Eurasian and the Indian Plate. Hence, it is important to study and develop spatial model and information tool to understand the seismic phenomenon. The geoinformatic technique plays a significant role in the analysis of geodatabase to study the natural disaster and hazard assessment. The main aim of the present study is to develop geospatial model based on earthquake hazard assessment tool (EaHaAsTo) through integrated geological and geoinformatic techniques to better understand the earthquake occurrences zones. The spatial and non-spatial data were collected and integrated in a GIS to prepare geospatial databases. The thematic and quantitative databases were generated, and analysis was carried out to understand the seismic characteristics of the study area. The geospatial model was developed by integrating thematic databases and geospatial analyzed using weighted linear combination method. Finally, the GIS based on customized EaHaAsTo was developed to visualize the output of the model in qualitative and quantitative forms.