Remotely India: Bundelkhand Mafic Dikes and Quartz Veins

Remotely India #14

Do you see anything striking (pun intended) about this geologic map of the Bundelkhand craton?

Source: Sarada Mohanty 2023- Proterozoic Basins of the Bundelkhand Craton

Notice that the green lines are predominantly oriented in a NW-SE direction. The pink lines are predominantly striking NE-SW. These are magmatic and fluid intrusions into the Bundelkhand granitic crust. The green lines represent mafic dikes (Mg and Fe rich basaltic magma), and the pink lines represent quartz veins. 

The Bundelkhand craton is an Archean age block of continental crust. Like other Archean age terrains, it has a long history of magmatism, volcanism, and sedimentation. The oldest rocks, a suite of granitic rocks going by the term 'tonalite–trondhjemite–granodiorite', and associated volcanics and chemical sediments are as old as 3.4 billion years. Through the Archean the crust grew by repeated injections of magma. Voluminous magmatism petered out by around 2. 4 billion years ago with the formation of the Bundelkhand granodiorite batholith, an enormous subsurface body of congealed magma. Granodiorite is a calcium feldspar bearing variant of granite. This younger rock type covers most of the surface area of this terrain.

Geologic activity continued for hundred of millions of years after the emplacement of this batholith with the intrusion of these impressive dike swarms and quartz vein clusters.

Staying true to the objective of this series on Indian geology as seen from satellite imagery, the emphasis here will be on the field features of these intrusive bodies.

Giant Quartz Veins:

Locality- Northeast of Mauranipur, Uttar Pradesh.

The quartz vein stands out as a high long ridge. Steep sided blocks of quartz make up the spine of the ridge. Weathered boulders shed from the quartz vein have formed the surrounding slopes. This distinctive landform is instantly recognizable in the imagery as you explore this region.  

Locality: Southeast of Mohangarh, Madhya Pradesh.

Here you can observe the intrusive relationship between the giant quartz vein and the older Bundelkhand granite (BG) which crops up as low hills made up of a light toned fractured rock. The linear vein can be traced cutting across the host rock.

Locality: Southeast of Mauranipur, Uttar Pradesh.

At this location you can observe an unusual feature. Two quartz veins have split to form a tuning fork shaped geomorphic feature.

These quartz veins intruded the crust around 2.15 to 2 billion years ago. The quartz crystals contain bubbles of gas and minuscule amounts of liquid trapped inside them. They inform us about the temperature and pressure during precipitation of the crystals and about the salinity of the fluid. There are also tiny crystals of other hydrous minerals like chlorite and epidote found inside the quartz. These reveal the source of the fluid. Such studies conducted by Duttanjali Rout and colleagues identify two distinct sources of fluids involved in the formation of these veins. A hot moderate salinity fluid derived from the Bundelkhand granodiorite mixed with meteoric water percolation downwards through fractures. The deeper fluids were sourced from not more than 5 km in the subsurface.

A drop in the temperature and pressure of the rising silica saturated fluid as it encountered the colder meteoric water resulted in decrease of silica solubility and the precipitation of quartz. The giant quartz veins are the product of a vigorous Proterozoic geothermal system that lasted tens of millions of years. The researchers have drawn a comparison with Broadlands-Ohaaki geothermal system in Northland, New Zealand, and the Kakkonda geothermal system in NE Japan. Both are in granitic terrains and could be loose analogs for the processes in operation during the formation of the Bundelkhand quartz veins.  

There are differences in what we can observe in these ancient and modern systems. In the Proterozoic example, the surface expression of the silica rich geothermal system, the hot springs and geysers, have long since eroded away. We can study only the subsurface plumbing system. In the modern settings, the surface processes are apparent and the underground patterns of fluid flow have to be inferred. 

Mafic Dikes:

Locality- Northeast of Lalitput, Uttar Pradesh,

A NNW-SSE trending dike is exposed near Tera village. The surface expression of mafic dikes is very different from the quartz veins. The dikes weather away faster and are exposed as low relief hills with extensive boulder fields derived from the weathering of the dolerite rock. In the satellite imagery, you can see the dark toned nature of the boulders hinting at its mafic composition. Due to the spread of boulders around the dike, the width of the intrusion appears far more that its true width. 

Locality- Mahoba , Uttar Pradesh

An ENE-WSW trending mafic dike is surrounded by Mahoba town. As with the NW-SE trending cluster, these E-W trending intrusions also appear as dark toned low relief boulder strewn hills.

Locality- Mahoba, Uttar Pradesh.

This is a synoptic view of the E-W trending dike, captured by ISRO Cartosat. The white rectangle in the lower left of the image is the bounding area covered by the previous imagery. It is quite an extensive intrusion, and to the eastern end it can be seen cutting across outcrops of the Bundelkhand granite. 

Geochronologic work on these mafic dikes shows that the NW-SE trending dike swarm intruded around 1.9 to 1.8 billion years ago. The E-W trending group of dikes are much younger, dated to about 1.1 billion years ago. 

The geochemistry of these dikes point to an upper mantle source of the magma. The dikes are a variety of thoeliitic basalt, not too much different from the basalts of the Deccan Traps in Maharashtra. Unlike the shallow sourced fluid of the quartz veins, the source magma of the dikes was generated at least 50 km down in the mantle lithosphere.

The crisscrossing lines you see on a geologic map of the Bundelkhand craton are a record of geologic activity that continued long after voluminous granitic magmatism ended. In rare exposures, mafic dikes are seen cutting across quartz veins, indicating that they are the younger of the intrusives. Most of the geochronology data collected so far supports this field observation. Studies of the spatial patterns of the dikes and quartz veins too hint that they represent two independent deformation events. The formation of both these systems required extensive fracturing and faulting  of the crust by extensional forces. Geologists are still working out the reasons for these crustal disturbances. 

In the case of the quartz veins, the fracture systems tapped relatively shallow sources of heat and fluids. In the subsequent reactivation of the crust, much deeper fracture systems cutting across the crust tapped upper mantle sources of heat,  providing conduits for the passage of mafic magma to shallower crustal levels. 

These deep crust penetrating fractures and Proterozoic mafic dike swarms tell another story about the strength of the crust and the advent of plate tectonics, but that is fuel for another post!

I am having fun resurrecting my Remotely India series. Stay in touch for more explorations of Indian geology on this blog.

Remotely India: Chittagong Tripura Fold Belt

Remotely India #13

Did you know that the easternmost part of the Bengal delta is being compressed into folded hill ranges? These go by the name Chittagong Tripura Fold Belt (CTFB), also referred to by geologists as the Outer Indo Burman (Myanmar) Ranges.

Take a look at the annotated satellite image below. The CTFB appears as a series of north south oriented ridges and valleys, extending from northern Tripura to south of Cox Bazaar in Bangladesh. 

Structurally they are made up of strata folded into anticlines (upwarps) and synclines (downwarps). To the east, they are separated from the inner Indo Burman (Myanmar) Ranges (IBR) by the north south trending Kaladan Fault. The Chittagong Coastal Fault marks the westernmost boundary of this fold belt, although the sedimentary pile below the sea bed of the Bay of Bengal to the west is also deforming. The 'deformation front' of this terrain is therefore further to the west of the Coastal Fault. 

As you might have guessed, these fold belts are a result of the Indian tectonic plate converging with Asia. But the nature of tectonic plate interaction is different from the plate collision that formed the Himalaya. In the case of the Himalaya, the continental crust of the Indian plate has collided with the continental crust of the Asia plate. The lower part of the Indian continental crust has slid under Tibet while thick slices of the Indian upper crust have been thrust up by faults to form the different geologic units of the Himalaya. 

Tracing the mountain arc southwards from its bend around Arunachal Pradesh, a different type of tectonic plate interaction is unfolding. In the Himalaya collision zone the more buoyant continental crust is sliding at a shallow angle underneath Tibet, a process known as underplating. In contrast, the Indian tectonic plate along this eastern convergence zone is made up of denser oceanic crust. As a result, along the zone of contact with Asia, this dense plate is subducting or taking a deep dive at a steeper angle into the mantle. 

Another difference apparent from the surface structure is the presence of both vertical and sideways movement of crustal blocks. This occurs because the Indian plate is pressing into Asia at an angle. Oblique convergence results in thrust faulting wherein rocks are moved up along east sloping fault planes. Collision at an angle also causes blocks to slide past each other along strike slip faults.  

The IBR is an older mountain chain formed by the subduction of the Tethyan oceanic crust underneath the Asia plate and the smaller Myanmar plate. This process, initiated in the Late Cretaceous around 100 million  years ago, eventually led to the formation of a complex fold belt by mid Miocene times (15-20 million years ago). 

This fold belt is made up of deep sea sediments and fragments of the Tethyan oceanic plate. These rocks were subjected to very high pressures during mountain building. Sheared and fractured rock units occur in a melange made up of dismembered blocks of varied rock types juxtaposed by faults. Heat and high pressure acting on rocks rich in aluminum, calcium, iron, titanium, and magnesium has resulted in the formation of deposits of exquisite gemstones such as jade, rubies, sapphires, spinel, and peridote. The IBR is studded with precious stones!

By Miocene (~20 million  years ago) the IBR had emerged above sea level as elevated ranges and had started eroding. Sediments shed from these hills were deposited in delta and shallow marine environments of the Bengal Basin to the west. During continued subduction of the Indian plate, between 2-4 million  years ago, this thin skin of the crust made up of about 5 km of sediment was scraped off, faulted, and crumpled up to form the CTFB. Geologists call these scraped off wedges of sediments that form along subduction zones as 'áccretionary prisms'. 

Further to the south, the Andaman Islands is also an accretionary prism formed along the plate junction between India and Asia.

The deformation of the CFTB diminishes from the east to the west. There are two distinct structural domains of this belt. To the east is a more tightly folded belt known as the Eastern Highly Compressed Fold Thrust Zone. Towards the west, is the more open Western Fold Thrust Zone. The emergent part of this fold belt is bounded to the west by the Chittagong Coastal Fault. However, geophysical studies show that the strata below the Bay of Bengal sea bed is also being warped and can be considered part of a westward growing CTFB.

The annotated satellite image below is a close up of the CTFB and the IBR. The black line is the Kaladan Fault separating the two, but even without my annotation, the two terrains have a distinctly different appearance. The older IBR have been more deeply dissected by streams. They have an etched faceted texture. To the west, the younger ranges of the CTFB have a more uniform even texture. 

Finally, I just wanted to put up a structural cross section of the CTFB. The folded and faulted nature of the sedimentary strata is apparent, as is the difference between the more tightly folded eastern zone compared with the more open western domain. Source: Md. Sakawat Hossian et.al. 2022: Lithosphere.

Scientists study terrains like the Chittagong Tripura Fold Belt to understand the mechanical response of the crust to different types of tectonic plate interactions. There is an economic incentive too. The IBR with its precious stone deposits has long been a target of exploration. In the CTFB natural gas seepage has been observed at many places. Geologists are interested in understanding the subsurface structure to target search for hydrocarbon accumulations.

As always, exploring Indian geology from satellite imagery is fun and a great learning experience for me. Stay tuned for more such stories!

Links: Europa Life, Moon Geology, Citizen Activism

Some readings I perused over the past couple of weeks.

1) Our picture of habitability on Europa, a top contender for hosting life, is changing. Jupiter's moon Europa has long been a contender for hosting life. But lately some scientists have expressed their doubts. Europa has an ocean beneath a 20 km icy crust. Geologists now think that the sea floor is not active. They simulated conditions which could generate shallow earthquakes leading to fault movement and exhumation of fresh rock. Reaction of sea water and freshly exposed rocks is necessary for chemical reactions that sustain life. Results suggest an inert sea floor. Another study implied no magmatism on Europa. Rising magma brings with it heat and chemicals. But, could these be transient conditions that we have caught? Maybe there is a cyclicity to Europa's energy flow. Some interesting thoughts in this article.

2) China's Moon atlas is the most detailed ever made. The Chinese Academy of Sciences has released a stunning 1:250,000 scale geologic map of the moon. A decade of research has revealed 17 rock types ( I used to think only basalt!), 81 basins, and 12,000 odd craters! Compiled from orbiting satellites and then sharpened using data from the two lander missions.

3) How Punekars fought for their hill, Vetal Tekdi, to save its ecology. My city Pune has a proud tradition of citizen activism. For the past few years citizens have vigorously protested a road planned along a forested hill slope. This hill has been a life saver for thousands of citizens as a recreation spot. It hosts rich biodiversity and is an important groundwater recharge zone. The Pune Municipal Corporation is insisting on building this road, despite their own reports admitting an adverse environmental impact, and pointing to at best a short term marginal improvement in traffic flow. The fight to save the hill goes back a couple of decades. Shobha Surin has done a good job summarizing this long battle in Question of Cities.   

Geological Contacts: Angular Unconformity Kaladgi Basin

 Remotely India Series #12

Through the Proterozoic Eon, beginning around 2 billion years ago,  extensional forces acting on continental crust opened up several sedimentary basins across what is now peninsular India. Crustal blocks subsided along faults and these depressions filled in with sediments deposited in fluvial and shallow marine environments. These basins were long lived, some lasting for more than a billion years. 

Sedimentation was not continuous.  Pulses of sediment deposition were punctuated by long periods of non deposition. Tectonic movements deformed early deposited piles of sediment. They were uplifted and an extensive basin wide erosional surface formed.

There was then a renewed phase of basin development. Sediment of these successor basins were deposited on tilted and folded older strata. Commonly, these younger packages of sediments are relatively undeformed. They are preserved as mesas and plateaus made up of flat lying strata. This discordance in attitude between two sets of strata separated by a widespread erosion surface is known as an angular unconformity.

In this post I will highlight an angular unconformity from the Kaladgi Basin from north Karnataka, south India. I have used high resolution imagery from Indian Space Research Organization's Cartosat.  Imagery is available for browsing and download from ISRO's Bhuvan 2D web maps.

The first image shows the area around Ramdurg village. The multi-stage history of the basin is readily apparent. The light colored strata exposed along narrow ridges are folded, while the rust brown hills are made up of undeformed sediments. The light toned strata are quartzites of the Bagalkot Group. The brown sandstone which rest on the Bagalkot quartzites are the Badami Group. Standard annotations show the varying dip and strike of the folded Bagalkot sediments. The white cross in grey circle denotes horizontal Badami strata. 

Kaladgi Basin history has become clearer based on recent geochronologic work by Shilpa Patil Pillai, Kanchan Pande, and Vivek S.Kale. They infer that basin initiation occurred around 1.4 billion years ago. Sedimentation of the Bagalkot Group terminated by 1.2 billion years ago. Movement along major WNW-ESE and tranverse NNE-SSE to NE-SW trending faults deformed the Bagalkot sediments into a series of folds around 1.1 billion years ago. This was followed by uplift and erosion of these folded sediments. Deformation was accompanied by low grade metamorphism of these rocks.

The basin floor subsided again around 900 million years ago initiating deposition of the Badami Group of sediments. The famous cave temples of Badami have been cut out from the lower part of the Badami sedimentary sequence.

The next imagery is a good example on how to recognize the relative timing of deformation events. Arrows point to fracture sets in the Bagalkot quartzites. These lineaments do not extend into the Badami sediments implying that fracturing occurred during an earlier phase of deformation. 

Let's look at a location that shows the angular discordance between the Bagalkot and Badami sediments. This is near Shirur town, north of Badami.  The lighter toned steeply tilted Bagalkot sediments outcrop as E-W trending narrow ribbons, north of Budanagad village. The brown colored Badami sediments form a more extensive plateau. Since these strata are horizontal, the traces of bedding planes form concentric bands mimicking contour lines. 

The final location is just south of Ramdurg village. The unconformity here is a little harder to decipher, but you can make out the tilt of the light colored Bagalkot quartzites, annotated by the standard notation of strike and dip. The quartzites form triangular facets sloping eastwards. Like the previous example, the concentric bands of brown in the adjacent hill indicates that this is the overlying horizontally disposed Badami sandstone.

Many Proterozoic basins of India contain such unconformity bounded sequences. Some more classic examples come from the Chattisgarh, Cuddapah, and Vindhyan basins. These sequences from different basins were not deposited synchronously. Each basin has it own trajectory of sedimentation, deformation, and erosion. 

Detailed field mapping, supplemented by absolute dating of rocks wherever possible, is elucidating the complex poly-phase history of Indian Proterozoic sedimentary basins in the context of global continental breakup and reassembly. For arm chair geologists and enthusiasts, easily available web mapping technology makes it possible to join in the excitement of teasing out these terrain's many secrets hiding in plain sight.

Geological Contact: Sirohi Fold Belt And Erinpura Granite

One of  my favorite courses during graduate work in Pune was geological Remote Sensing. We focused a lot on visual interpretation of aerial photographs and satellite imagery. Lab work meant hours of poring over different areas of India and making preliminary geology maps based on observations of the landforms and rock structures visible from space. The rock composition, structure, and weathering patterns controls the surface expression of geological units. These are manifest on satellite imagery and on aerial photographs as differences in tone, texture, structural styles, and relief. 

I came across a nice example of the juxtaposition of two distinct geologic rock units just northeast of the town of Sirohi in Rajasthan. 

These two terrains made up of the Erinpura Granite and the Sirohi Group sediments are easily recognizable. 

The terrain west of the yellow line and isolated ribbons between the purple lines is made up of layered metamorphosed sedimentary rocks of the Sirohi Group. These sediments were deposited on the Erinpura Granite basement around 850 million years ago. Hard rock layers form northeast southwest oriented ridges with intervening valleys underlain by a softer lithology.  The texture appears fine and the ridge and valley terrain has a substantial vegetation cover. The rock layers can be traced as a series of folds. The Sirohi Group sediments were deformed and metamorphosed by 820 million years ago.

The Erinpura Granite represents magmatism that occurred around 900 million years ago.  Occurring mostly east of the yellow line, the granite also forms enclaves (orange outline) in the fold belt.

The granite appears as a light toned surface. It is massive body of rock, lacking the layering seen in the western sedimentary basin. The landform is a low elevation plain as compared to the Sirohi rocks.The rock has a coarse granular texture. Its surface has scant vegetation. Several lineaments (dark colored lines) are seen crisscrossing the granite body. These are fractures and dikes. Shrubs and trees growing along the fractures and dikes give them a darker appearance and make them stand out against the lighter granite body. The fracture sets have also controlled the local drainage. Several streams can be seen flowing along straight courses.

Below are two close up images of the contact zones between the two terrains. 

At this scale you can appreciate why the granite as a coarser texture in the synoptic imagery. The fracture systems has broken the granite in to a blocky surface. 

In this image below the Erinpura Granite occurs as an enclave surrounded by Sirohi metasedimentary rocks. 

And finally, a close up of structure controlled drainage in the Eripura Granite terrain. The fir tree like pattern, known as trellis drainage,  is due to streams flowing along orthogonal fracture sets. 

Geology mapping done. Now to visit Rajasthan for a field check! 

LInks: India Aquifers, Early Bipedalism, Mars Geology

 Here are some interesting articles I read recently.

1) Mapping India's Aquifers.  Indian agriculture depends heavily on groundwater. To understand and manage this resource we need a good idea of the nature and extent of aquifers. Subodh Yadav, Joint Secretary, Department of Water Resources, River Development and Ganga Rejuvenation, Ministry of Jal Shakti, has written an informative article on the National Aquifer Mapping Program. Detailed reports are available to the public through the Central Ground Water Board, Aquifer Information and Management System page. Mapping and report availability is still work in progress.

2) Is Sahelanthropus the earliest biped? A good article by Brian Handwerk on the many questions spawned from a recent analysis of a 7 million year old femur fossil. Fossil remains named Sahelanthropus tchadensis were found nearly 20 years ago in Chad, and various studies have come to conflicting conclusions on whether Sahelanthropus could walk on two legs. Bipedalism is considered to be one of the key traits distinguishing members of the human branch from other apes and so there is a vital interest in understand the timing and circumstances of its evolution. 

3) Ground Penetrating Radar images from Mars Perseverance Rover. The indefatigable Mars Rover loaded with geological instruments is currently exploring the edge of the Jezero Crater on Mars. Here, rivers emptied into a large lake depositing sediment and building a delta. The first radar images show inclined sedimentary layers which could be the classic sign of a delta architecture or something else, scientists suspect. Read on! By Holly Ober, University of California, Los Angeles.

Remotely India: Structural Control On Drainage

 Remotely India #10

Check out this amazing example of fracture controlled stream flow. Follow blue arrows.

The stream originates on the steep west facing slopes of Tamhini Ghat (west of Pune) and flows a north westerly course in a NW-SE trending fracture, then makes an abrupt left turn and flows south west into a NE-SW trending fracture. It then exhibits a number of right angle turns. Finally, it turns sharply and flows north along a N-S trending fracture before joining the larger Kundalika river near Mhasewadi.

This area comprising the edge of the Deccan Volcanic Plateau and the coastal plain has been shattered by several fracture systems which formed due to tensile forces affecting the western margin of India during and post Deccan volcanism.

Take some time looking at this image above. You will see scores of small streams flowing along fractures and making sharp turns at fracture intersections. The geomorphology of this part of the Deccan Volcanic Province is a joy to explore.

The Lost Rivers Of The Harappan Civilization- Remote Sensing Analysis

A lot of ink has been spent of this topic, both in the scientific literature as well as in popular books about the Harappan Civilization. The focus of many of these efforts has been on locating the "Vedic Saraswati", a river mentioned in the Rig -Ved. It is described as occupying the region between the Yamuna and the Sutlej and has been identified by many workers as the present day Ghaggar-Hakra.

Settlements of the Harappan Civilization were spread out over quite a large area in northwest India. Hence, it is necessary to map in detail the broader once existing hydrologic networks to assess the relationship between settlements and patterns of water availability and water use. This study uses remote sensing data and image processing techniques to unearth some of the buried paleo-river networks of this region of northwest India.

Twenty eight years of Landsat 5 imagery totaling 1711 multi-spectral images was bulk processed. This use of data covering multiple dates in a year allowed the investigators to reduce visibility issues related to shifting land use and cultivation, changing moisture patterns and variable cloud cover. 8000 km of paleo-river channels were mapped, some identified in previous studies, but many recognized anew.

The paper describes the various image processing techniques used to tease out the spectral signatures of the buried rivers. Don't be alarmed by words like Normalized Difference Vegetation Seasonality Index (NDVSI), Principal Component Analysis and the Tasselled Cap Transform.  One can understand the final interpretations without getting into the details of these techniques. Let me give a brief idea though.

These are techniques has increase the contrast between vegetation, soils with different moisture levels and bare terrain. For example, due to stronger water flow the river channel itself and the levees it builds contain coarser sediment as compared with the adjoining floodplains. These coarser sediment contain less organic matter and are less fertile. Less vegetation grows on the buried channels and levees than on the more fertile fine grained floodplain sediment. This contrast shows up well on data processed using NDVSI which essentially maps the vigor of vegetation. This technique was useful in delineating channels in the northern part of the study area.

The southeast part of the study area is more arid and has less changes in vegetation across the landscape. Here, the Tasselled Cap Transform was more useful in identifying river channels. This techniques organizes the spectral information into several (usually three) main axis or bands of information. One axis contains data variability of reflectance of bare terrain (mineral mixtures). The second contains variability in greeness (vegetation), and the third contains variability of wetness (water and soil moisture). Again, to give an example, this southeast region is fed by rivers draining Aravalli limestones. The calcium carbonate leached away from the rock is precipitated along river channels as a chalky mineral deposit. Buried channels show up as ribbons of  bright reflectance in  the Tasseled Cap Transform brightness band. Imagery of the dry months shows these channels more clearly, since in the wet months, increased soil moisture reduces the contrast of calcium carbonate rich sediment.

A judicious use of such techniques thus enabled the researchers to identify buried networks with different vegetation, soil moisture and mineral brightness properties. 

A map of the interpreted buried rivers is posted below.

Source: Hector A. Orengo and Cameron A. Petrie 2017

Of importance is a critique of some previous studies which attempted to highlight the spatial relationship between river channels and archaeological sites (emphasis mine):

The data provided by these analyses are also important in contextualising previous studies in which palaeo-rivers have been dated using the distribution of known archaeological sites. Notwithstanding the positional accuracy of these locations (see [10,63,64]), which would severely hamper their use for validation purposes, the results for the northern sector of the study area (Figure 3) suggest that proximity to the river might not be a good indication of contemporaneity as the fields close to the river channel might not have been the most productive in agricultural terms. Sites with an agricultural orientation might have preferred to occupy elevations above flooding level in the finer sediment accumulation area. Flooding events and changing river courses could also have had an important effect in the preservation of archaeological sites eroding and burying those that were locatedin the path of new courses or in their sediment accumulation areas.

In addition to these factors, the scale at which these correlations between specific palaeo-channels and settlement locations have usually been published (e.g., [30] (pp. 359–387), [31] (Figure 4.2)]) do not allow the accurate correlation between the two elements. The use of large area (small scale in a geographic sense) site distribution maps for these correlations results in a visual association between the shape of the palaeo-river and the line formed by the grouping of sites, but at these scales the sites could be aligned to a number of palaeo-channels given the number of rivers and the parallel morphology of the drainage in the Sutlej-Yamuna interfluve revealed here. This analysis thus suggests that at these scales it is not possible to co-relate lineal distribution of archaeological sites to any particular palaeo-river that we have documented. The results from previous studies reconstructing the chronology of the hydrological system using the position of archaeological sites and vice versa(e.g., [24,25], [30] (pp. 359–384), and [31]) are, therefore, considered unreliable.

..and

Given the complexity of the hydrological system, the variety in the climatic and weather system of this region, and the diversity of ways that ancient populations are likely to have obtained water, it is unwise to use the date of occupation at specific settlements to date when specific channels carried water. It is essential to date the different palaeo-courses independently to properly reconstruct the evolution of hydrological networks over long periods. The chronologically consistent reconstruction of this palaeo-river network would allow the testing of different hypothetical scenarios of water availability through the use of network analysis in combination to hydrological analysis.

Interesting work. Open Access.

History Of India Land Use Changes- 1880 To 2010

Notable Effort:

In India, human population has increased six-fold from 200 million to 1200 million that coupled with economic growth has resulted in significant land use and land cover (LULC) changes during 1880–2010. However, large discrepancies in the existing LULC datasets have hindered our efforts to better understand interactions among human activities, climate systems, and ecosystem in India. In this study, we incorporated high-resolution remote sensing datasets from Resourcesat-1 and historical archives at district (N = 590) and state (N = 30) levels to generate LULC datasets at 5 arc minute resolution during 1880–2010 in India. Results have shown that a significant loss of forests (from 89 million ha to 63 million ha) has occurred during the study period. Interestingly, the deforestation rate was relatively greater under the British rule (1880–1950s) and early decades after independence, and then decreased after the 1980s due to government policies to protect the forests. In contrast to forests, cropland area has increased from 92 million ha to 140.1 million ha during 1880–2010. Greater cropland expansion has occurred during the 1950–1980s that coincided with the period of farm mechanization, electrification, and introduction of high yielding crop varieties as a result of government policies to achieve self-sufficiency in food production. The rate of urbanization was slower during 1880–1940 but significantly increased after the 1950s probably due to rapid increase in population and economic growth in India. Our study provides the most reliable estimations of historical LULC at regional scale in India. This is the first attempt to incorporate newly developed high-resolution remote sensing datasets and inventory archives to reconstruct the time series of LULC records for such a long period in India. The spatial and temporal information on LULC derived from this study could be used by ecosystem, hydrological, and climate modeling as well as by policy makers for assessing the impacts of LULC on regional climate, water resources, and biogeochemical cycles in terrestrial ecosystems.

See this comparison

Source: Tian et al. 2014

The massive increase in cropland density over the Indo-Gangetic plain and the diminishing of forest over the Himalayan belts, Central India and Western Ghats is brought out starkly. The forests of the north east though appear to be in a better shape somewhat than other parts of India.

The paper makes a good point that deforestation was higher during colonial times and early days of Independence. The British saw forests as a resource to be exploited, a legacy that continued  after Independence as well. Post 1980's, Forest protection policies did put the brakes on massive deforestation. This however hides some details. Two year surveys of forest cover and forest health by Forest Survey of India reveals that denser canopy forests are being degraded, prime forest land continues to be diverted for development, and the band aid and balancing the book trick that is known as compensatory afforestation is not always meeting its goals and occasionally ends up causing more damage to the environment.

The article comes with lots of details about methodology used and a good reference list.

Open Access

Assessment Of India Coastal Erosion

Some data points on changes in India's coastline due to erosion and accretion over 15 years (1989-91 to 2004-2006)

Assessment of coastal erosion along the Indian coast on 1 : 25,000 scale using satellite data of 1989–1991 and 2004–2006 time frames 

The  long  stretch  of  coastline  on  either  side  of the Indian  peninsula  is  subjected  to  varied  coastal  processes  and  anthropogenic  pressures,  which  makes  the coast vulnerable to erosion. There is no systematic inventory  of  shoreline  changes  occurring  along  the  entire  Indian coast  on 1:25,000  scale, which is required for  planning  measures  to  be  taken  up  for  protecting the coast at the national level. It is in this context that shoreline  change  mapping  on  1:25,000  scale  for  the entire Indian coast based on multi-date satellite data in GIS  environment  has  been  carried  out  for  1989–1991 and  2004–2006  time  frame.  The present  communication discusses  salient  observations  and  results  from  the shoreline   change inventory.   The   results   show   that 3829 km (45.5%) of the coast is under erosion, 3004 km (35.7%)  is  getting accreted, while  1581 km (18.8%)  of the coast is more or less stable in nature. Highest percentage  of  shoreline  under  erosion  is  in the Nicobar Islands (88.7), while the percentage of accreting coastline  is  highest for  Tamil  Nadu  (62.3)  and Goa  has the highest   percentage   of   stable   shoreline   (52.4).   The analysis shows that the Indian coast has lost a net area of  about  73 sq.km  during  1989-1991  and  2004–2006 time  frame.   In Tamil Nadu,   a   net  area   of  about 25.45 sq.km has increased due to accretion, while along the Nicobar Islands  about  93.95 sq. km  is  lost  due  to erosion.  The  inventory  has  been  used  to  prepare a Shoreline Change Atlas of the Indian Coast.

Background geological processes keep reshaping coastlines, but this short time frame assessment seems to have captured several anthropogenic disturbances. And one big natural event- the 2004 Indian Ocean tsunami appears to have caused considerable erosion in the Andaman and Nicobar Islands.

Cartosat 1 DEM- Two Strike Slip Faults

My two favorite strikes slip faults in India as rendered by Cartosat 1 Digital Elevation Model-

1) Yamuna Left Lateral Fault-

Source: Cartosat 1 DEM National Remote Sensing Center, ISRO

You can see that the Siwalik hills are breached by the Yamuna and dislocated in a left lateral sense, i.e. one would have to turn left to follow the narrow marker rock bed across the fault.

From a previous post on this fault-

Miocene onwards a thick wedge of fluvial sediments filled up a foreland basin that formed in front of rising thrust sheets uplifted along the active Main Boundary Thrust (MBT). That phase ended about 0.5 to 1 mya.

This fluvial wedge over the last half a million years has been deformed into the Siwalik mountains. These mountains form broad synclines and tight anticlines cut by north dipping thrust faults, a result of the continuing compression of the sediment wedge. The southernmost of these thrusts which brings into tectonic contact the anticlinal Frontal Range of the Siwaliks over the alluvial plains in called the Himalayan Frontal Thrust (HFT).

The HFT is broken into segments and the amount of displacement along these segments or thrust blocks is unequal. For example the blocks west of the Yamuna and east of the Ganga have moved southwards with an opposite sense of movement relative to the central block known as the Dun block. To view this, turn on labels and pan southeastwards in embeddable map below until the town of Haridwar where the Ganga enters the plains.

Thus the Yamuna fault has a left lateral sense of movement while the Ganga fault has a right lateral sense of movement. These faults can be thought of as lateral ramps of the HFT accommodating the displacement caused by the southwards movement of the HFT blocks. 

Structural considerations indicate that during the last 0.5 my there has been about 8 km of displacement along the Yamuna and Ganga faults, a slip rate of approx. 16 mm year. - See more at: http://suvratk.blogspot.in/2010/12/remotely-india-3-left-lateral-yamuna.html#sthash.H9K4tfrI.dpuf

 Miocene onwards a thick wedge of fluvial sediments filled up a foreland basin that formed in front of rising thrust sheets uplifted along the active Main Boundary Thrust (MBT). That phase ended about 0.5 to 1 mya.

This fluvial wedge over the last half a million years has been deformed into the Siwalik mountains. These mountains form broad synclines and tight anticlines cut by north dipping thrust faults, a result of the continuing compression of the sediment wedge. The southernmost of these thrusts which brings into tectonic contact the anticlinal Frontal Range of the Siwaliks over the alluvial plains in called the Himalayan Frontal Thrust (HFT).

The HFT is broken into segments and the amount of displacement along these segments or thrust blocks is unequal. For example the blocks west of the Yamuna and east of the Ganga have moved southwards with an opposite sense of movement relative to the central block known as the Dun block. To view this, turn on labels and pan southeastwards in embeddable map below until the town of Haridwar where the Ganga enters the plains.

Thus the Yamuna fault has a left lateral sense of movement while the Ganga fault has a right lateral sense of movement. These faults can be thought of as lateral ramps of the HFT accommodating the displacement caused by the southwards movement of the HFT blocks.

Structural considerations indicate that during the last 0.5 my there has been about 8 km of displacement along the Yamuna and Ganga faults, a slip rate of approx. 16 mm year.

The Digital  Elevation Model also brings out beautifully the Quaternary alluvial fans with tiers of river terraces deposited in the valley between the Siwaliks and the Lesser Himalayas and the intricate drainage on the southern slopes of the Siwalik frontal range.

2) Gani Kalava Fault-

This too has a left lateral movement and has a prolonged history of being reactived during different phases of sedimentation in the Proterozoic Cuddapah Basin of south India.  I  did my M.Sc dissertation on this area, concentrating on the asymmetric anticline with a gentler dipping southern limb and a nearly vertical dipping northern limb located south of Gani village.

Source: Cartosat 1 DEM, National  Remote Sensing Center, ISRO

From a previous post on this fault-

The feature is an ENE plunging asymmetric anticline with spectacular dip slopes of quartz arenites making up the southern limb of the fold and left-lateral movement along a regional fault steepening the northern limb of the fold. There is some copper mineralization along the fault. The Cuddapah basin is an intra-cratonic basin which was filled up in several depositional mega cycles. Sections of two of these mega cycles are exposed in this area. The older mega cycle comprising the Cuddapah subgroup is exposed in the core of the anticline. An angular unconformity separates the older cycle from the younger Kurnool cycle (sub group) which is exposed along the limbs.

Brown arrows shows the offset marker beds (grey arrows show sense of movement) of the oldest sedimentary formation of the Cuddapah basin, the early Proterozoic Gulcheru Quartzites and Vempalle limestones of the Papaghani Group. These lie unconformably on the Archean Peninsular  Gneiss which is the fawn colored peneplain in the left part of the DEM. The very distinct dip slopes of  the Gani anticline (south of Gani village) are made up of a much younger sedimentary unit, the Banganpalle  Quartzites of the Kurnool Group. They were deposited in energetic shallow seas, forming a vast sand shelf, wherein waves and currents winnowed out unstable minerals, leaving behind a nearly pure well sorted and rounded quartz sand. The quartz grains are polycyclic, meaning they show evidence of being derived by weathering of older sandstones, the most likely source being the Gulcheru Quartzites.

Remember this is a Digital Elevation Model,  same color means the same altitude range and not mineral composition.

Free Download- Cartosat 1 India 1 Arc Sec Digital Elevation Model

I've been writing periodic updates on Bhuvan and have been critical about some of its features before. Today I sing its praise.

Bhuvan is the Indian Space Research Organization's web mapping portal. It was  launched with much hype in 2009, touted by the media as a Google Earth killer.  That it hasn't turned out to be. Google Earth /Maps is still the most used application for browsing imagery and exploring the world's surface.

This need not have been portrayed by the media as a Google versus Bhuvan competition. I always felt Bhuvan would offer real value by making available India specific natural resources and earth science datasets to overlay imagery. That in fact is the direction Bhuvan has been evolving for the past few years.

Bhuvan now offers a variety of  India datasets for overlay, analysis and download. I have been playing around with the Digital Elevation Model (DEM) derived from Cartosat 1 stereo imagery. The DEM is available as 1 degree tile corresponding to the Survey of India topo map sheets. The interface  to  select and download the DEM is easy to use. Technical documentation of the DEM is also available. Spatial resolution is 1 Arc Sec, which corresponds to around 30 meters. The vertical margin of  error is about 8 meters. Analysis shows that the Cartosat DEM compares well with other widely used DEM such as SRTM (90 m res) and ASTER (30 m res).

Below is  a Digital Elevation Model of the Nallamalai Hills in Andhra Pradesh with a 0.5 deg graticule overlain. I've generated this representation in Manifold GIS. The geological terrain is part of the Proterozoic Cuddapah Basin. Remember, the color scheme assigned to the DEM is not demarcating different rock types but elevation ranges. However, as a nod to the prominent geological feature that I wanted to highlight, I have assigned a color of the common rock in outcrop. These are the Bairenkonda Quartzites and Sandstones of the Nallamalai Group which form folded ridges, part of the Nallamalai fold belt. The green low relief areas are mostly underlain by shales and limestones.

And check out the drainage in color black (lowest elevation). You can make out the drainage divide between the Godavari and Krishna basins. In the upper right part of the image, streams are draining north towards the Godavari river. In the left lower part of the DEM, streams are flowing south towards the Krishna river.

Source: Cartosat 1 DEM, National Remote Sensing Centre, ISRO

I'm planning to tell more stories about Indian geology using these DEM 's. For that I  have to thank ISRO for making this dataset available.

Hyperspectral Remote Sensing- Open Access Papers In Current Science

Current Science has a special section (open access) on Hyperspectral  Remote Sensing with papers on applications in geology, soil mapping, glacial dynamics, forestry and planetary sciences. Hyperspectral Remote Sensing involves measuring the energy from visible and infrared spectrum at very narrow intervals or channels. For example, the Hyperion sensor collects spectral information in 220 spectral bands from between the 0.4 to 2.5 µm (micrometer) bandwidth with a 30-meter ground resolution. This means scientists can use this data to identify surface objects with subtly different spectral properties. I've written about the applications of hyperspectral remote sensing in geology in an earlier post on the use of this technique in Afghanistan.

Here is a short excerpt from that post on the utility of hyperspectral imaging for mineral identification:

For the map of Afghanistan, the USGS used a sensor known as HyMap imaging spectrometer loaded aboard an aircraft. It collected spectral data covering 128 bands of 15-20 nm  (nanometer) bandwidth in the 0.4 to 2.5 µm (micrometer) range i.e the visible and the near infrared spectrum with a 5 meter ground resolution. Minerals have distinctive absorption signatures,  meaning that when sunlight strikes the surface of the earth the O-H or C-O3 or Si-O2 or Fe-OH bonds in the mineral absorb energy at a distinct wavelength, each covering a very narrow portion of the spectrum . Because conventional multispectral sensing collects energy averaged over a  broad interval it cannot discriminate between individual minerals. Hyperspectral sensing is fine grained enough (15-20 nm bandwidth) to be able to resolve the distinctive absoption signatures of several minerals.

here is the list of papers in Current Science-

Preface
Advances in spaceborne hyperspectral imaging systems
Hyperspectral image processing and analysis
Algorithms to improve spectral discrimination from Indian hyperspectral sensors data
Hyperspectral remote sensing of agriculture
Hyperspectral remote sensing: opportunities, status and challenges for rapid soil assessment in India
Monitoring of forest cover in India: imaging spectroscopy perspective
Hyperspectral remote sensing and geological applications
Snow and glacier investigations using hyperspectral data in the Himalaya
Simulating the effects of inelastic scattering on upwelling radiance in coastal and inland waters: implications for hyperspectral remote sensing
Hyperspectral remote sensing of planetary surfaces: an insight into composition of inner planets and small bodies in the solar system

 

Are Himalayan Glaciers Retreating?

Open Access in Current Science- A remote sensing survey of 2018 glaciers across the Himalayan arc for the time period 2001 -2010 was carried out. Change in snout position was compared. The majority of glaciers over the last ten years show stable snout positions. About 12% show retreat and only 0.9% show advancement. Himalayan glaciers are retreating though. Studies that cover larger time periods have shown that studied glaciers have been in retreat over all of the last century with the largest retreats from the mid 1970's to the late 1990's. Glaciers have been naturally shrinking since the last Ice Age ended with few reversals such as the younger Dryas and the Little Ice Age, but the past 100 years or so are of interest to us due to the impact of anthropogenic global warming.

Glacial retreat may have slowed down in the last decade and no doubt given the complex response of ice masses to their situation in a particular topographic setting and temperature changes such variations in rates of change of glacier decay will continue as the earth warms. Besides, as other water experts have pointed out , the big problem with interpreting the true significance of Himalayan glacier behavior is the lack of crucial baseline data for a) the amount of snowfall in the various Himalayan glacial source areas and b) much of the reporting of changes in glaciers present area changes and not changes in volume. The volume of ice corresponds to the volume of water held, so any assessment of damage to north Indian river supply must study volume change of ice as glacial melt contributes substantially to Himalayan river water flow. Furthermore, such data if it does exist and that collected in the future must be made public to be examined by as many experts as needed and not kept secret as has been the case with Himalayan river water data in the past. So, a lot more work in terms of basic data gathering needs to be done. 

In any case such larger scale studies are useful pointers to regional trends and for pinpointing areas deserving more detailed studies.

Abstract:

The Himalayan mountain system to the north of the Indian land mass with arcuate strike of NW–SE for about 2400 km holds one of the largest concentration of glaciers outside the polar regions in its high-altitude regions. Perennial snow and ice-melt from these frozen reservoirs is used in catchments and alluvial plains of the three major Himalayan river systems, i.e. the Indus, Ganga and Brahmaputra for irrigation, hydropower generation, production of bio-resources and fulfilling the domestic water demand. Also, variations in the extent of these glaciers are understood to be a sensitive indicator of climatic variations of the earth system and might have implications on the availability of water resources in the river systems. Therefore, mapping and monitoring of these fresh  water resources is require d for the planning of water resources and understanding the impact of climatic variations. Thus a study has been carried out to find the change in the extent of Himalayan glaciers during the last decade using IRS LISS III images of 2000 /01/02 and 2010/11. Two thousand and eighteen glaciers representing climatically diverse terrains in the Him a-laya were mapped and monitored. It includes glaciers of Karakoram, Himachal, Zanskar, Uttarakhand, Nepal and Sikkim regions. Among these, 1752 glaciers (86.8%) were observed having stable fronts (no change in the snout position and area of ablation zone), 248 (12.3%) exhibited retreat and 18 (0.9%) of them exhibited advancement of snout. The net loss in 10,250.68 sq km area of the 2018 glaciers put together was found to be 20.94 sq km or 0.2% (2.5 % of 20.94 sq km).

Paranoia Over Google Mapping Tools Persists In Indian Officialdom

sigh... I keep writing about this only partly as comedy.. but mostly in frustration...

From an article in the Hindu about the recently held "mapathon"contest organized by Google.

As Delhi Police investigates whether Google violated rules in holding a competition that asked users to add information about their local areas for its online map, the U.S. Internet giant on Saturday said it had responded to queries raised by Survey of India more than 10 days back and hasn’t heard from it yet. (emphasis mine)

Apparently, the Survey of India and the Defence establishment is worried that such initiatives will have grave security repercussions.  The problem is that Google has been asking users to add information about their local areas for its online map for several years now. I just don't comprehend how a mapping contest wherein lots of enthusiasts add places of interest on a map within a short span of time becomes a greater security threat than an individual using Google Maps on any other day of the year.

more from this article in the Economic Times... But on behalf of the Surveyor General of India Swarna Subba Rao, his deputy major general R C Padhi told the three ministries that Mapathon was "not in accordance with the national Mapping Policy 2005 and map restriction policies issued by the defence ministry from time to time", sources said.

Added a senior defence officer, "Such activities can have serious security repercussions in case mapping of restricted areas is undertaken by members of the general public."

The words "general public" come out of the mouths of our officials with such contempt and suspicion. These archaic mapping policies which restrict the "general public" from mapping certain areas have long been rendered meaningless by the many roving eyes that hover above the earth. I am sure the government understands this.. but relinquishing control over anything has always been hard for Indian officialdom.

The exceedingly vast majority of people using Google applications to map India don't want to harm India.

Those who do... might I remind the Indian Government that the terrorists who attacked Mumbai on November 26 2008 did not wait for a mapping contest to survey the city.

ISRO Plans New High Resolution Remote Sensing Satellite

...but will the public have easy access to the data?

Something this article does not address. India's remote sensing program is no doubt a great science and technology success and the imagery and digital data is being used by scientists for research and natural resource management.

Where India and ISRO are falling short is the continued denial of the best quality images to the public at large.  Bhuvan - ISRO's  answer to Google Maps - launched a few years ago is still serving images of India which are frustratingly inadequate for users who have by now become accustomed to razor sharp quality images of their cities and countryside from Google Maps and Google Earth.

The remote sensing satellite Cartosat-2 series has been imaging India using a panchromatic sensor at a 0.8 meter resolution since 2007.  In July 2011 India announced a new Remote Sensing data policy which allowed distribution of 1 meter resolution imagery without additional security checks. The previous policy did not allow unrestricted access to imagery finer than 5.8 meters. The policy change should ideally have resulted in image streaming applications like Bhuvan to present much sharper images of India. Almost two years since we are still getting a grainy view of India from Bhuvan.  Is the new policy not extendable to open access image streaming applications? If so, why not? Pointing to reasons of national security does not make sense since fine resolution imagery is already available through applications like Google Maps to users in India.

The image below of a portion of Pune city is the best resolution available via Bhuvan and it means that tens of millions of potential users will stay away and use Google instead.

Hyperspectral Mapping Of The Geology Of Afghanistan

This post submitted to the Accretionary Wedge # 48 hosted by Earth-like Planet. The theme is "Geoscience and Technology" and this post is on the use of multi and hyperspectral remote sensing for geological mapping.

Coinciding with the 40th anniversary of the Landsat series of remote sensing satellites, two maps of the surface distribution of several distinctive minerals covering a large portion of Afghanistan has been released by the USGS.

 Source: USGS Pub A

These maps have been prepared by processing the reflectance properties of surface materials captured by sensors aboard a plane. Conventional satellite mapping like that prepared from Landsat data does the same thing but it generally captures less information. For example, most conventional commercial satellites will capture reflected energy in the visible and the near infra red portion of the spectrum in 4 - 7 bands.

This type of remote sensing of the reflected and emitted energy from surface material is termed multispectral sensing. Recently, new satellites have started capturing hyperspectral data. Here, the energy from the visible to infrared spectrum is collected at very narrow intervals or channels. For example, NASA's Hyperion sensor aboard the EO-1 satellite is capable of collecting spectral information in 220 spectral bands from between the 0.4 to 2.5 µm (micrometer) bandwidth with a 30-meter ground resolution.

Catching Illegal Mining In Goa Using Google Earth

Ogle Earth points to the use of open access tools like Google Earth to alert us to the possibility of illegal mining. From their blog:

There is a juicy scandal unfolding in India’s smallest and richest state, Goa, where the State Assembly’s Public Accounts Committee (PAC) has prepared a report indicting ruling Congress Party politicians for benefiting from illegal mining in the state. Illegal mining is estimated (by the Hindustan Times) to have cost Goa over USD 600 million over the past five years in lost tax revenues, turning this into a whopper of a story.....

...India’s national Directorate of Mines and Geology has now also taken an interest in the mine, ordering it to immediately cease production until it is investigated. An article by Goa’s Herald spells it out for us:

Tarcar has cheated the government by avoiding huge amounts of export duty by under-invoicing of his exports.

When presented with evidence of massive ore dumps that could not have been produced within quota, his mining company contended that these were from earlier activities. Google Earth’s imagery from 2003 effectively catches the company in a lie.

Check out the imagery here. No open pit mines in 2003. The 2011 imagery shows large open pit mines.

These ores are part of the rich iron ore belt of Goa. They are Precambrian Banded Iron Formations generally thought to be of sedimentary origin and are associated with medium and high grade meta-sedimentary rocks of the Archean schist terrain that makes up large portions of south India.

Indian Remote Sensing Data Policy Has Been Updated

A country that has launched ten remote sensing satellites has finally decided to share some of its riches with the true custodians of that data - its citizens.

The Government of India recently announced its new data policy for the management and dissemination of satellite remote sensing data. Of most interest to users is that data upto 1 meter resolution will be disseminated to all users on a "non-discriminatory basis". Previously only government users had easier access to 1 meter resolution images. Only data upto 5.8 meter resolution was being distributed to private users without permissions and security clearances.  With this new policy, the 1 meter data is still going to be pre-screened by the government to mask sensitive areas, but no further permissions will be required.

This policy although an improvement is still restrictive. If you are a private user or a private company and want data better than one meter taken from foreign or Indian satellites you will need to be approved by the government if you want to buy this best data in India. Several foreign satellites and the Indian Cartosat -2A and 2B collect sub-meter images. Data purchase in India is from the National Remote Sensing Centre.

You can of course purchase data of India taken from foreign satellites outside India also, which was one of the arguments that restrictions of any kind just don't make any sense.

What does this mean for different users of satellite data?

1) If you are a professional user of satellite images and are working with the Indian government then not much. You always had easy access to high resolution data.

2) If you are a private user or a private company then you will find ordering 1 meter resolution images easier. No further screening of your application will be necessary and you should be able to get hold of the data quicker than before.

3) For the casual user- Will Bhuvan - ISRO's flagship web mapping application - start streaming 1 meter resolution images of India?  Until now because of policy restrictions it could stream only 5.8 meter resolution images at best. This affects the non-professional user, people who are currently going to Google Maps or Google Earth for browsing images of India. If Bhuvan starts streaming 1 meter resolution images will more people move from Google to Bhuvan?

I doubt it. Google is streaming superb high resolution images of India and it may even release - or already has - sub- meter images which Bhuvan will be unable to do due to restrictions on dissemination of data better than one meter. Besides there is the problem of usability and performance. I am not very impressed with Bhuvan. The image loading is slow. The one advantage that Bhuvan had claimed over Google was India specific additional layers on natural resources. Yet I found that rendering of these layers is non-optimal and geo-processing tasks are not compatible with all browsers. In short, Bhuvan still has the look of an unfinished product. As far as popular usage of satellite images goes, Google has a substantial hold on Indian users and it looks like it will stay that way.

Does The Indian Govt Prefer Google Over Bhuvan?

From a note in Geospatial World I learn that the Election Commission (EC) of India might be using Google satellite images as a background layer on which to placemark the locations of polling booths along with relevant information. The project will be initiated in the state of Bengal.

If this report of using Google is true, I am curious to know why the EC chose Google over Bhuvan which also serves out satellite images and is advertised by the Indian Space Research Organization (ISRO) to be customizable to incorporate the kind of functionality the EC wants.

Is it because - a) the EC was not aware of Bhuvan and its capabilities? In that case, ISRO has not done a good job of educating potential users about Bhuvan.

Or is it because - b) the Application Programming Interface i.e. the programming tools that allow developers to customize the application is not good enough?

Or is it because - c) Data policy restricts even government departments from accessing very high resolution imagery (1 meter) from Indian satellites for web applications, even internal ones like the proposed polling booth app. Government users may obtain without clearances high res images of a pre-defined extent i.e. images of one particular geographic area, but is a high res seamless image stream available to them through  Bhuvan?

Currently the data policy allows only imagery of resolution 5.8 meters and coarser to be released free of clearances in the public domain. Due to this policy Bhuvan can only stream images of 5.8 meters and coarser to the general public. The policy is supposed to be up for a review this year.

Whatever the reasons, it's a shame that Bhuvan and high resolution imagery captured by Indian satellites is being kept away from being utilized in innovative applications.

The government and ISRO need to introspect.