Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geolog... more Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
An analogy between submarine channels and fluvial rivers has existed for long, especially on the ... more An analogy between submarine channels and fluvial rivers has existed for long, especially on the basis of planform and morphometry. Underlying this broad resemblance are the minute disparities that shape and control these systems. In order to observe and quantify the variations between submarine channels and subaerial rivers, we present a first-ever geomorphometric investigation of one single system, where the fluvial river is compared with its offshore counterpart from source-to-sink. With exhaustive data from the submarine fan, parameters like longitudinal profile, width, sinuosity, slope and planform of the Indus Fan channel-levee complex (CLC) are estimated and compared on the basis of the same parameters estimated for the fluvial Indus River. Our new data analyses offers key insights into the variable geomorphometric patterns prevalent from the source of the Indus River until the margins of the submarine Indus Fan. Channel width and sinuosity vary from high-to-low downstream in the submarine system and from low to high in the fluvial basin. Characteristic depositional features of either system are mutually exclusive. Longitudinal profiles of the submarine fan and the river basin do not conform-principally due to the difference in intensity of erosional and depositional processes active in both regions. These differences are primarily attributed to a single-point (canyon-fed) distributary flow and a multi-point (tributary-fed) cumulative flow source system, and density contrasts between river flows and turbidity currents. By quantifying this variation, our attempt is to dissuade the long-standing morphometric analogy between fluvial rivers and submarine channels.
The Indus basin—one of the largest fluvial-controlled landscapes of the world, provides a major a... more The Indus basin—one of the largest fluvial-controlled landscapes of the world, provides a major agro-economic resource base while showcasing unique morphometry along its course. However, despite its large socioeconomic relevance in South Asia, a distinct account of morphometric variations down its course still remains elusive. Here, for the first time a quantitative demarcation of the Indus basin into—upper, middle, and lower basin is proposed based on analyses of critical morphometric parameters (viz. gradient/river length ratio, elevation-relief ratio, channel width, sinuosity, and slope). Geostatistical and hydrological operations performed on digital elevation models, suggest that the highest and lowest relief sectors are tectonically more stable than the middle relief sector, inferred from a convex hypsometric curve. Elevation-relief ratio for the basin indicates tectonic stability with ~ 31% of remnant rock still in place. Cross-sectional transects also demonstrate anomalous patterns that deviate from predictive characteristics of youthful, mature, and senile stages of river development. All parameters are spatially coalesced to provide a first-ever holistic morphometric account of the Indus basin while describing fine-scale planform variations of the spectacular dynamics of this enormous river basin.
Since the advent of the United Nations Convention on the Law of the Sea (UNCLOS), coastal countri... more Since the advent of the United Nations Convention on the Law of the Sea (UNCLOS), coastal countries have recognised the opportunity of extending their jurisdiction along the natural prolongation of their continental landmass – granting them an unprecedented thrust of economic empowerment. States that ratify UNCLOS are mandated to scientifically establish the continuity of their continental margins, beyond 200 nautical miles (nm). As a prelude to this, coastal states are required to demarcate their maritime boundaries – an exercise often complex and seldom free from disputes with adjoining or opposite states. Two noteworthy decisions in the case of India-Bangladesh and Bangladesh-Myanmar maritime delimitation resulted in the inception of a new terminology in maritime history-the 'grey area', a state of ambiguity that continues to exist even after three years of adjudication. This article draws attention to the causative circumstances that led to the development of such a scenario; its ramifications in terms of overlapping rights; while suggesting possible propositions for conflict resolution.
The Indus fan in the Arabian Sea is the second largest submarine fan in the world after the Benga... more The Indus fan in the Arabian Sea is the second largest submarine fan in the world after the Bengal fan. Despite being an extensive physiographic and sedimentary feature, detailed mapping of the channel systems is very limited. Identification of five unreported deep sea channels using multibeam swath bathymetry data (collected by NCAOR) led to the outset of this study. Based on this survey in conjunction with the global seafloor topography data, here we present a GIS approach to report a " Projected Channel System " (PCS). Identification of the PCS is dependent on the calculation of flow direction. The values of flow direction raster range from 1 to 128, where 1 represents east; 4 depicts south; 16 is west and north is shown as 64. Subsequent calculation of flow accumulation and ordering of streams helped in marking major and minor streams. The method has successfully captured channel systems belonging not just to Indus drainage basin but several others, in an area of 3.03 x 10 6 km 2. Data from previously published channel systems – belonging to the Indus system were used to validate the results. Average offset distance between previously identified channels and PCS channels was ~10 km, indicating a reasonably good overlap.
Multibeam swath bathymetry survey was carried out
in the middle Indus fan region in the eastern A... more Multibeam swath bathymetry survey was carried out in the middle Indus fan region in the eastern Arabian Sea. Using high-resolution bathymetry data, major morphological features such as the Raman seamount and the Laxmi ridge have been mapped. This study also reveals the presence of sinuous channel systems, continuing towards the distal fan. Though there are several reports on the presence of channels in different regions of the Indus fan, we report here the presence of active channels to the east of the Laxmi ridge. The total length of all channels along the channel axis is about 915 km. The individual spreads of the channels vary from 189.8 to 1980.5 m. Most of the channels are shallow with the average depth measuring about 60 m. The longest channel is about 256.3 km long, 702 m wide and about 57 m deep. The channels observed are similar to the land-based fluvial channels. The channels identified are highly sinuous in nature, their meanders and cut-off meanders are similar to the characteristics of fluvial channels. In general, average channel course in the study area is more than twice the straight course.
The identification of temporal change in the extent
of coral reefs and mangroves patches along th... more The identification of temporal change in the extent of coral reefs and mangroves patches along the Narara and Kalubhar islands was performed using multi-temporal data from 1999 to 2010 (LISS III and LISS IV (MX)). For extracting coral reefs, the reflectances of the feature were studied and using a few sample locations identified by seatruthing, the reflectances of the corals were observed in different bands. Since these values were not normally distributed, it was considered best to use the modal value of the dataset. The final range was taken as ±1 from the mode, which was used for the extraction of coral pixels. The findings suggested that the coral cover depleted from 19.35 to 9.11 km2 in the study area. The second objective of extracting the mangroves was accomplished by employing the technique of Principal Component Analysis (PCA). This technique gave better results as it not only identified the mangrove swamps but also differentiated between the dense and sparse. The greatest variance in the dataset could be identified by this method, thereby making it easier to outline the variations existing within the mangroves. The findings highlighted that out of the total area mangroves covered 38.81 km2 in 2010 while in 1999, they covered only 30.69 km2 ascertaining the impact of mangrove restoration projects functioning in the area.
Extracting high-quality building footprints is a basic requirement in multiple sectors of town pl... more Extracting high-quality building footprints is a basic requirement in multiple sectors of town planning, disaster management, 3D visualization, etc. In the current study, we compare three different techniques for acquiring building footprints using (i) LiDAR, (ii) object-oriented classification (OOC) applied on high-resolution aerial photographs and (iii) digital surface models generated from interpolated LiDAR point cloud data. The three outputs were compared with a digitized sample of building polygons quantitatively by computing the errors of commission and omission, and qualitatively using statistical operations. These findings showed that building footprints derived from OOC gave highest regression and correlation values with least commission error. The R 2 and R values (0.86 and 0.92, respectively) imply that the footprint areas derived by OOC matched more closely with the actual area of buildings, while a low commission error of 24.7% represented a higher number of footprints as correctly classified.
In the present study an attempt has been made to identify the demand of each
household in the stu... more In the present study an attempt has been made to identify the demand of each household in the study area, in order to divide the villages into pockets of high, moderate and low priority for provision of electrification. This division is based on a “Priority Index” that has been designed in a manner to address the variations in electricity demand also considering the socio-economic background of the household dwellers. Parameters that were applied in order the assess the socio-economic status were, monthly income/ expenditure, rate of literacy, occupational structure, number of school going children, size of household and level of poverty i.e. identification of APL/BPL households. Out of these, the most significant contributors were included in the computation of a bias free Priority Index. The spatial division (as per priority) was helpful in proposing potential locations for the placement of new transformers, providing higher spatial coverage with planned energy allocation and minimized transmission loss. According to this methodology, a holistic categorization was achieved which closely identified the pockets needed to be given highest priority for providing electricity, without compromising on greatest spatial coverage. The average percentage of households that remained uncovered across the five villages studied was 9.68 % only, promising a reasonably high coverage.
The December 2004 Sumatra–Andaman earthquake emphasized consistent and comprehensive assessment o... more The December 2004 Sumatra–Andaman earthquake emphasized consistent and comprehensive assessment of areas that are prone to the hazard of Tsunami. It also focused attention on the hazards that could be posed by large subduction zone earthquakes and the Tsunamis that could be further generated. Due to the extremely high vulnerability in the Andaman Islands in South East India, it is essential for planners to develop a comprehensive a priori information database in order to minimize the impact of these destructive situations. A similar effort has been done in this study wherein the entire Andaman Islands have been assessed to target ‘‘Tsunami Hazard Vulnerable areas’’ in accordance with the maximum wave run-up heights and topography. These areas have been extracted from the total area keeping in mind the run-up wave heights on the very day of the Sumatra– Andaman earthquake, i.e., on December 26, 2004. Also, the topographic variations in the region have been studied to establish a relation between the vulnerability of an area and its topography. The hazard of Tsunami puts at threat, the lives of approximately 314,084 people over an area of 5,833.1 km2 in the Andaman Islands. Out of the total area, 708.8 km2 is the hazardous portion which is 12.1 %. The islands have experienced a total of 386 earthquakes (above 5.0 magnitude) from the time of Sumatra–Andaman Tsunami till the end of 2009. These statistics clearly indicate the need for hazard preparedness and planning in order to minimize impact during unfortunate circumstances. This study thus aims at the preparation of Tsunami Hazard Vulnerability Map for the Andaman Islands which can be further used by administrative and disaster mitigation organizations as and when required.
Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geolog... more Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
An analogy between submarine channels and fluvial rivers has existed for long, especially on the ... more An analogy between submarine channels and fluvial rivers has existed for long, especially on the basis of planform and morphometry. Underlying this broad resemblance are the minute disparities that shape and control these systems. In order to observe and quantify the variations between submarine channels and subaerial rivers, we present a first-ever geomorphometric investigation of one single system, where the fluvial river is compared with its offshore counterpart from source-to-sink. With exhaustive data from the submarine fan, parameters like longitudinal profile, width, sinuosity, slope and planform of the Indus Fan channel-levee complex (CLC) are estimated and compared on the basis of the same parameters estimated for the fluvial Indus River. Our new data analyses offers key insights into the variable geomorphometric patterns prevalent from the source of the Indus River until the margins of the submarine Indus Fan. Channel width and sinuosity vary from high-to-low downstream in the submarine system and from low to high in the fluvial basin. Characteristic depositional features of either system are mutually exclusive. Longitudinal profiles of the submarine fan and the river basin do not conform-principally due to the difference in intensity of erosional and depositional processes active in both regions. These differences are primarily attributed to a single-point (canyon-fed) distributary flow and a multi-point (tributary-fed) cumulative flow source system, and density contrasts between river flows and turbidity currents. By quantifying this variation, our attempt is to dissuade the long-standing morphometric analogy between fluvial rivers and submarine channels.
The Indus basin—one of the largest fluvial-controlled landscapes of the world, provides a major a... more The Indus basin—one of the largest fluvial-controlled landscapes of the world, provides a major agro-economic resource base while showcasing unique morphometry along its course. However, despite its large socioeconomic relevance in South Asia, a distinct account of morphometric variations down its course still remains elusive. Here, for the first time a quantitative demarcation of the Indus basin into—upper, middle, and lower basin is proposed based on analyses of critical morphometric parameters (viz. gradient/river length ratio, elevation-relief ratio, channel width, sinuosity, and slope). Geostatistical and hydrological operations performed on digital elevation models, suggest that the highest and lowest relief sectors are tectonically more stable than the middle relief sector, inferred from a convex hypsometric curve. Elevation-relief ratio for the basin indicates tectonic stability with ~ 31% of remnant rock still in place. Cross-sectional transects also demonstrate anomalous patterns that deviate from predictive characteristics of youthful, mature, and senile stages of river development. All parameters are spatially coalesced to provide a first-ever holistic morphometric account of the Indus basin while describing fine-scale planform variations of the spectacular dynamics of this enormous river basin.
Since the advent of the United Nations Convention on the Law of the Sea (UNCLOS), coastal countri... more Since the advent of the United Nations Convention on the Law of the Sea (UNCLOS), coastal countries have recognised the opportunity of extending their jurisdiction along the natural prolongation of their continental landmass – granting them an unprecedented thrust of economic empowerment. States that ratify UNCLOS are mandated to scientifically establish the continuity of their continental margins, beyond 200 nautical miles (nm). As a prelude to this, coastal states are required to demarcate their maritime boundaries – an exercise often complex and seldom free from disputes with adjoining or opposite states. Two noteworthy decisions in the case of India-Bangladesh and Bangladesh-Myanmar maritime delimitation resulted in the inception of a new terminology in maritime history-the 'grey area', a state of ambiguity that continues to exist even after three years of adjudication. This article draws attention to the causative circumstances that led to the development of such a scenario; its ramifications in terms of overlapping rights; while suggesting possible propositions for conflict resolution.
The Indus fan in the Arabian Sea is the second largest submarine fan in the world after the Benga... more The Indus fan in the Arabian Sea is the second largest submarine fan in the world after the Bengal fan. Despite being an extensive physiographic and sedimentary feature, detailed mapping of the channel systems is very limited. Identification of five unreported deep sea channels using multibeam swath bathymetry data (collected by NCAOR) led to the outset of this study. Based on this survey in conjunction with the global seafloor topography data, here we present a GIS approach to report a " Projected Channel System " (PCS). Identification of the PCS is dependent on the calculation of flow direction. The values of flow direction raster range from 1 to 128, where 1 represents east; 4 depicts south; 16 is west and north is shown as 64. Subsequent calculation of flow accumulation and ordering of streams helped in marking major and minor streams. The method has successfully captured channel systems belonging not just to Indus drainage basin but several others, in an area of 3.03 x 10 6 km 2. Data from previously published channel systems – belonging to the Indus system were used to validate the results. Average offset distance between previously identified channels and PCS channels was ~10 km, indicating a reasonably good overlap.
Multibeam swath bathymetry survey was carried out
in the middle Indus fan region in the eastern A... more Multibeam swath bathymetry survey was carried out in the middle Indus fan region in the eastern Arabian Sea. Using high-resolution bathymetry data, major morphological features such as the Raman seamount and the Laxmi ridge have been mapped. This study also reveals the presence of sinuous channel systems, continuing towards the distal fan. Though there are several reports on the presence of channels in different regions of the Indus fan, we report here the presence of active channels to the east of the Laxmi ridge. The total length of all channels along the channel axis is about 915 km. The individual spreads of the channels vary from 189.8 to 1980.5 m. Most of the channels are shallow with the average depth measuring about 60 m. The longest channel is about 256.3 km long, 702 m wide and about 57 m deep. The channels observed are similar to the land-based fluvial channels. The channels identified are highly sinuous in nature, their meanders and cut-off meanders are similar to the characteristics of fluvial channels. In general, average channel course in the study area is more than twice the straight course.
The identification of temporal change in the extent
of coral reefs and mangroves patches along th... more The identification of temporal change in the extent of coral reefs and mangroves patches along the Narara and Kalubhar islands was performed using multi-temporal data from 1999 to 2010 (LISS III and LISS IV (MX)). For extracting coral reefs, the reflectances of the feature were studied and using a few sample locations identified by seatruthing, the reflectances of the corals were observed in different bands. Since these values were not normally distributed, it was considered best to use the modal value of the dataset. The final range was taken as ±1 from the mode, which was used for the extraction of coral pixels. The findings suggested that the coral cover depleted from 19.35 to 9.11 km2 in the study area. The second objective of extracting the mangroves was accomplished by employing the technique of Principal Component Analysis (PCA). This technique gave better results as it not only identified the mangrove swamps but also differentiated between the dense and sparse. The greatest variance in the dataset could be identified by this method, thereby making it easier to outline the variations existing within the mangroves. The findings highlighted that out of the total area mangroves covered 38.81 km2 in 2010 while in 1999, they covered only 30.69 km2 ascertaining the impact of mangrove restoration projects functioning in the area.
Extracting high-quality building footprints is a basic requirement in multiple sectors of town pl... more Extracting high-quality building footprints is a basic requirement in multiple sectors of town planning, disaster management, 3D visualization, etc. In the current study, we compare three different techniques for acquiring building footprints using (i) LiDAR, (ii) object-oriented classification (OOC) applied on high-resolution aerial photographs and (iii) digital surface models generated from interpolated LiDAR point cloud data. The three outputs were compared with a digitized sample of building polygons quantitatively by computing the errors of commission and omission, and qualitatively using statistical operations. These findings showed that building footprints derived from OOC gave highest regression and correlation values with least commission error. The R 2 and R values (0.86 and 0.92, respectively) imply that the footprint areas derived by OOC matched more closely with the actual area of buildings, while a low commission error of 24.7% represented a higher number of footprints as correctly classified.
In the present study an attempt has been made to identify the demand of each
household in the stu... more In the present study an attempt has been made to identify the demand of each household in the study area, in order to divide the villages into pockets of high, moderate and low priority for provision of electrification. This division is based on a “Priority Index” that has been designed in a manner to address the variations in electricity demand also considering the socio-economic background of the household dwellers. Parameters that were applied in order the assess the socio-economic status were, monthly income/ expenditure, rate of literacy, occupational structure, number of school going children, size of household and level of poverty i.e. identification of APL/BPL households. Out of these, the most significant contributors were included in the computation of a bias free Priority Index. The spatial division (as per priority) was helpful in proposing potential locations for the placement of new transformers, providing higher spatial coverage with planned energy allocation and minimized transmission loss. According to this methodology, a holistic categorization was achieved which closely identified the pockets needed to be given highest priority for providing electricity, without compromising on greatest spatial coverage. The average percentage of households that remained uncovered across the five villages studied was 9.68 % only, promising a reasonably high coverage.
The December 2004 Sumatra–Andaman earthquake emphasized consistent and comprehensive assessment o... more The December 2004 Sumatra–Andaman earthquake emphasized consistent and comprehensive assessment of areas that are prone to the hazard of Tsunami. It also focused attention on the hazards that could be posed by large subduction zone earthquakes and the Tsunamis that could be further generated. Due to the extremely high vulnerability in the Andaman Islands in South East India, it is essential for planners to develop a comprehensive a priori information database in order to minimize the impact of these destructive situations. A similar effort has been done in this study wherein the entire Andaman Islands have been assessed to target ‘‘Tsunami Hazard Vulnerable areas’’ in accordance with the maximum wave run-up heights and topography. These areas have been extracted from the total area keeping in mind the run-up wave heights on the very day of the Sumatra– Andaman earthquake, i.e., on December 26, 2004. Also, the topographic variations in the region have been studied to establish a relation between the vulnerability of an area and its topography. The hazard of Tsunami puts at threat, the lives of approximately 314,084 people over an area of 5,833.1 km2 in the Andaman Islands. Out of the total area, 708.8 km2 is the hazardous portion which is 12.1 %. The islands have experienced a total of 386 earthquakes (above 5.0 magnitude) from the time of Sumatra–Andaman Tsunami till the end of 2009. These statistics clearly indicate the need for hazard preparedness and planning in order to minimize impact during unfortunate circumstances. This study thus aims at the preparation of Tsunami Hazard Vulnerability Map for the Andaman Islands which can be further used by administrative and disaster mitigation organizations as and when required.
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Papers by Prerna Ramesh
in the middle Indus fan region in the eastern Arabian
Sea. Using high-resolution bathymetry data, major
morphological features such as the Raman seamount
and the Laxmi ridge have been mapped. This study
also reveals the presence of sinuous channel systems,
continuing towards the distal fan. Though there are
several reports on the presence of channels in different
regions of the Indus fan, we report here the presence
of active channels to the east of the Laxmi ridge.
The total length of all channels along the channel axis
is about 915 km. The individual spreads of the channels
vary from 189.8 to 1980.5 m. Most of the channels
are shallow with the average depth measuring about
60 m. The longest channel is about 256.3 km long,
702 m wide and about 57 m deep. The channels
observed are similar to the land-based fluvial channels.
The channels identified are highly sinuous in
nature, their meanders and cut-off meanders are similar
to the characteristics of fluvial channels. In general,
average channel course in the study area is more
than twice the straight course.
of coral reefs and mangroves patches along the Narara and
Kalubhar islands was performed using multi-temporal data
from 1999 to 2010 (LISS III and LISS IV (MX)). For
extracting coral reefs, the reflectances of the feature were studied
and using a few sample locations identified by seatruthing,
the reflectances of the corals were observed in different
bands. Since these values were not normally distributed,
it was considered best to use the modal value of the dataset.
The final range was taken as ±1 from the mode, which was
used for the extraction of coral pixels. The findings suggested
that the coral cover depleted from 19.35 to 9.11 km2 in the
study area. The second objective of extracting the mangroves
was accomplished by employing the technique of Principal
Component Analysis (PCA). This technique gave better results
as it not only identified the mangrove swamps but also
differentiated between the dense and sparse. The greatest variance
in the dataset could be identified by this method, thereby
making it easier to outline the variations existing within the
mangroves. The findings highlighted that out of the total area
mangroves covered 38.81 km2 in 2010 while in 1999, they
covered only 30.69 km2 ascertaining the impact of mangrove
restoration projects functioning in the area.
household in the study area, in order to divide the villages into pockets of high, moderate
and low priority for provision of electrification. This division is based on a “Priority
Index” that has been designed in a manner to address the variations in electricity demand
also considering the socio-economic background of the household dwellers. Parameters
that were applied in order the assess the socio-economic status were, monthly income/
expenditure, rate of literacy, occupational structure, number of school going children,
size of household and level of poverty i.e. identification of APL/BPL households. Out of
these, the most significant contributors were included in the computation of a bias free
Priority Index. The spatial division (as per priority) was helpful in proposing potential
locations for the placement of new transformers, providing higher spatial coverage with
planned energy allocation and minimized transmission loss. According to this methodology,
a holistic categorization was achieved which closely identified the pockets needed
to be given highest priority for providing electricity, without compromising on greatest
spatial coverage. The average percentage of households that remained uncovered across
the five villages studied was 9.68 % only, promising a reasonably high coverage.
total area keeping in mind the run-up wave heights on the very day of the Sumatra– Andaman earthquake, i.e., on December 26, 2004. Also, the topographic variations in the region have been studied to establish a relation between the vulnerability of an area and its topography. The hazard of Tsunami puts at threat, the lives of approximately 314,084 people over an area of 5,833.1 km2 in the Andaman Islands. Out of the total area, 708.8 km2 is the hazardous portion which is 12.1 %. The islands have experienced a total of 386 earthquakes (above 5.0 magnitude) from the time of Sumatra–Andaman Tsunami till the end of 2009. These statistics clearly indicate the need for hazard preparedness and planning in order to minimize impact during unfortunate circumstances. This study thus aims at the preparation of Tsunami Hazard Vulnerability Map for the Andaman Islands which can be further used by administrative and disaster mitigation organizations as and when required.
in the middle Indus fan region in the eastern Arabian
Sea. Using high-resolution bathymetry data, major
morphological features such as the Raman seamount
and the Laxmi ridge have been mapped. This study
also reveals the presence of sinuous channel systems,
continuing towards the distal fan. Though there are
several reports on the presence of channels in different
regions of the Indus fan, we report here the presence
of active channels to the east of the Laxmi ridge.
The total length of all channels along the channel axis
is about 915 km. The individual spreads of the channels
vary from 189.8 to 1980.5 m. Most of the channels
are shallow with the average depth measuring about
60 m. The longest channel is about 256.3 km long,
702 m wide and about 57 m deep. The channels
observed are similar to the land-based fluvial channels.
The channels identified are highly sinuous in
nature, their meanders and cut-off meanders are similar
to the characteristics of fluvial channels. In general,
average channel course in the study area is more
than twice the straight course.
of coral reefs and mangroves patches along the Narara and
Kalubhar islands was performed using multi-temporal data
from 1999 to 2010 (LISS III and LISS IV (MX)). For
extracting coral reefs, the reflectances of the feature were studied
and using a few sample locations identified by seatruthing,
the reflectances of the corals were observed in different
bands. Since these values were not normally distributed,
it was considered best to use the modal value of the dataset.
The final range was taken as ±1 from the mode, which was
used for the extraction of coral pixels. The findings suggested
that the coral cover depleted from 19.35 to 9.11 km2 in the
study area. The second objective of extracting the mangroves
was accomplished by employing the technique of Principal
Component Analysis (PCA). This technique gave better results
as it not only identified the mangrove swamps but also
differentiated between the dense and sparse. The greatest variance
in the dataset could be identified by this method, thereby
making it easier to outline the variations existing within the
mangroves. The findings highlighted that out of the total area
mangroves covered 38.81 km2 in 2010 while in 1999, they
covered only 30.69 km2 ascertaining the impact of mangrove
restoration projects functioning in the area.
household in the study area, in order to divide the villages into pockets of high, moderate
and low priority for provision of electrification. This division is based on a “Priority
Index” that has been designed in a manner to address the variations in electricity demand
also considering the socio-economic background of the household dwellers. Parameters
that were applied in order the assess the socio-economic status were, monthly income/
expenditure, rate of literacy, occupational structure, number of school going children,
size of household and level of poverty i.e. identification of APL/BPL households. Out of
these, the most significant contributors were included in the computation of a bias free
Priority Index. The spatial division (as per priority) was helpful in proposing potential
locations for the placement of new transformers, providing higher spatial coverage with
planned energy allocation and minimized transmission loss. According to this methodology,
a holistic categorization was achieved which closely identified the pockets needed
to be given highest priority for providing electricity, without compromising on greatest
spatial coverage. The average percentage of households that remained uncovered across
the five villages studied was 9.68 % only, promising a reasonably high coverage.
total area keeping in mind the run-up wave heights on the very day of the Sumatra– Andaman earthquake, i.e., on December 26, 2004. Also, the topographic variations in the region have been studied to establish a relation between the vulnerability of an area and its topography. The hazard of Tsunami puts at threat, the lives of approximately 314,084 people over an area of 5,833.1 km2 in the Andaman Islands. Out of the total area, 708.8 km2 is the hazardous portion which is 12.1 %. The islands have experienced a total of 386 earthquakes (above 5.0 magnitude) from the time of Sumatra–Andaman Tsunami till the end of 2009. These statistics clearly indicate the need for hazard preparedness and planning in order to minimize impact during unfortunate circumstances. This study thus aims at the preparation of Tsunami Hazard Vulnerability Map for the Andaman Islands which can be further used by administrative and disaster mitigation organizations as and when required.