Posts Tagged ‘Landsat’
Landscape & Ecology in the Nilgiri Hills: A Spatial Exploration
View form Mettupalayam train station looking north to the slopes of the Nilgiri Hills. The famous Nilgiri Mountain railway steam engine is warming up for the morning ride up to Conoor. Thirty minutes later it took Lenny, Merrick and me up the hill. (Composite digital image taken in July 2009).
The Nilgiri Hills are an important range in the Western Ghats range. The broader Nilgiris area, located at the tri-junction of Tamil Nadu, Kerala and Karnataka, contains a variety of contrasting ecosystems and have the largest elevated plateau area in the Western Ghats. The Nilgiri Hills have been designated a “biosphere reserve” and include key protected areas including Silent Valley, Mukkurthy, Mudumalai and Bandipur National Parks (see the Keystone Foundations’ page for details). The Nagarhole, Wayanad and Satyamangalam forests adjoin the Nilgiris and thus it represses a vast protected area. Several important groups of people have lived in the hilly area prior to colonization by the British in the early 19th Century. The town of Ooty (Udhagamandalam) became the summer capital of the Madras Presidency and was the largest, most cosmopolitan hill station in southern imperial India. Many of the early scientific investigations of Western Ghats flora and fauna were conducted in the Nilgiris and adjoining areas. In fact, according to Paul Hocking, the leading authority on the area, the Nilgiris are said to be one of the most studied areas in Asia (see his interview in One Earth Foundation).
I’ve had a chance to visit the Nilgiris on several occasions since my first trip in the early 1990s. Initially I went on behalf the PHCC to make contact with individuals and groups working on conservation issues. On the first visit I had the opportunity to interact with Richard Radcliffe, a key figure in the post independence conservation movement in the Nilgiris. Later I returned on my own to work on recording landscapes as part of my ongoing Western Ghats documentation project. Most of the landscapes in this post are from those visits. On a recent trip to Silent Valley and Ooty (see previous blog post) I was immersed in the area’s ecology and landscapes and decided to work with some of the spatial data that I have gathered from various web portals.
My interest in the cartography of the Nilgiri Hills was sparked by an exquisite early 20th Century wall map in the Nilgiri Library. Roughly two meters wide it depicted relief, land use, hydrology, settlements, transport and other key elements. It was most likely a Survey of India product reflecting the high-end cartography that they made available to the public in an age before digital mapping and map restrictions related to security. There are few maps (and almost none that are publically available of the Western Ghats ranges) that come close to the science and art in those early SOI maps. I looked for it on this trip but the wall map has apparently been put away and is not publicly displayed anymore.
Two of the attached maps below utilize the 30 m SRTM Digital Elevation Model released by NASA/USGS in 2014 (Bhuvan also has DEMs available but they have voids and gaps that make it difficult to get a seamless base layer)(see announcement). The attached maps also highlight land cover data from the Western Ghats Biodiversity portal courtesy of my friend Prabhakar and his colleague J.P. Pascal (French Institute Pondicherry). The two NASA Landsat images look at the same area in 1973 and 2014. This provides a visual overview of changes similar to what I did in my “Land Cover Changes in the Palani Hills: A Preliminary Visual Assessment” blog post from April 2014. The issue of land cover changes, as evidenced in satellite imagery and terrestrial photos, continues to be an issue that I am interested in investigating using GIS and photo documentation.
Nilgiri Hills relief & elevation map (click twice on image for larger 150 DPI A3 version).
Cairn Hills Shola in the Nilgiri Hills (left side of image) with adjoining eucalyptus plantations and former grasslands converted to agricultural plots. (Digital image, June 2006)
Emerald Reservoir, one of several large hydroelectric projects in the upper Nilgiri Hills. Tea is grown in the foreground, whereas further back there are large non-native timber (eucalyptus) plantations. The monsoon mist hides the protected grasslands and sholas of Mukkurthy National park. (Digital image, June 2006).
Toda home near Avalanche in the south-western Nilgiri Hills. Note the large shola in the background. The grasslands here have been converted into vegetable plots. (Digital image, June 2006).
Looking south, south-west from the Western Catchment area in Mukkurthy National Park towards Bangittapal. This part of the Nilgiris -known as the Kundhas- has some of the most dramatic scenery in the entire Western Ghats. As is evident in the picture, Mukkurthy supports significant areas of montane grasslands interspersed with shola pockets and lone Rhododendron trees. After hydroelectric dams were built here in the 1960s the Western Catchment area became a popular site for Hindi and Tamil film makers. It is now off limits to movie makers and the general public and is protected for its biodiversity (notably Nilgiri tahr as well as large predators such as tigers). It took me significant time and effort to obtain the permissions to visit and make these few photographs (taken during a very short ½ day visit in January 1995).(120 film image scanned)
Devil’s Gap at Western Catchment. Here granite cliffs drop precipitously into the Nilambur Valley in Kerala. A chasm is hidden along the line of shola vegetation parallel to the cliff. With the montane grasslands, Rhododendron trees and cliffs in the background, Devil’s Gap makes for a most unusual Western Ghats landscape. I find similarities between this site and Devil’s Kitchen in the Palani Hills. At Devil’s Kitchen the encroaching plantations have obliterated the feel of the grasslands surrounding wind-sculpted sholas growing around the deep, hidden gorges. Taken on T-max 100 film using a Fujica 6×9 120 fixed lens camera. (January 1995).
Looking north to Devil’s Gap from the escarpment at Western Catchment in Mukkurthy National Park. Note the undulating hills supporting montane grasslands free of non-native timber plantations. As seen in the maps below, there are few areas left in the Nilgiri Hills where this once dominant vegetation still exists. Significant work is now being conducted by the Tamil Nadu Forest Department and NGOs to protect and restore montane grasslands in the Nilgiris. (Taken on Kodak T-max 100 film using a Fujica 120 6×9 fixed lens camera in January 1995).
Looking south from Masinagudi to the Nilgiri Plateau. (Digital image, June 2006)
Nilgiri Hills Vegetation & Land Cover Map (click twice on image for larger 150 DPI A3 version)
1973 Landsat image of Nilgiri Hills (click twice on image for larger 150 DPI A3 image)
2014 Landsat Nilgiri Hills map (click twice on image for larger 150 DPI A3 image)
REFERENCES
Chhabra, Tarun. The Toda Landscape: Explorations in Cultural Ecology. New Delhi: Oriental Black Swan/Harvard, 2015. Print.
Hockings, Paul. Encyclopedia of the Nilgiri Hills: Parts 1 & 2. New Delhi: Manohar, 2012. Print.
Lakshumanan, C. et al. “Landuse/Land cover dynamics study in Nilgiris district part of Western Ghats, Tamil Nadu.” International Journal of Geomatics and Geosciences. Volume 2, No. 3 2012. Web.
Lockwood, Ian. “Into the Blue Mountains on Steam Power.” Ian Lockwood Blog. 7 September 2009. Web.
Lockwood, Ian. “Land Cover Changes in the Palani Hills: A Preliminary Visual Assessment.” Ian Lockwood Blog. 4 April 2014. Web.
Lockwood, Ian. “Landscape and ecology in India’s Western Ghats: A Personal Odyssey.” Asian Geographic. July 2008. Print & Web.
Nalina, P. et al. “Land Use Land Cover Dynamics of Nilgiris District, India Inferred From Satellite Imageries.” American Journal of Applied Sciences. 11 (3) 455-461, 2014. Web.
Satish, K.V. et al. “Geospatial assessment and monitoring of historical forest cover changes (1920–2012) in Nilgiri Biosphere Reserve, Western Ghats, India.” Environmental Monitoring Assessment. 12 August 2014. Web.
Walker, Anthony R. The Toda of South India: A New Look. Delhi: Hindustan Publishing Corporation, 1986. Print.
Varma, Kalyan. “Revisiting Nilgiris’ Peaks and Passes.” Kalyan Varma Website. 7 August 2009. Web.
Sahyadri Revealed
Four part Landsat study of the Sahyadris based on imagery collected in February 2014.
The northern portion of the Western Ghats have a unique volcanic geology that makes them quite different from the southern ranges. The Sahyadris include the ranges extending from the Goa-Karnataka-Maharashtra tri-junction to their northern most point at the Tapti River (in Gujarat). The term “Sahyadri” is also widely used to describe the whole Western Ghats chain but geographically and geologically it is a segment of the larger heterogeneous assemblage called the Western Ghats.
Konkan Kada views on Harishchandragad looking south and north-west into the sunset. This is surely one of the most dramatic and breathtaking views in the Sahyadris. I led a group of MUWCI students and faculty members her in January of 2004 and we spent a spectacular evening sleeping out on the edge of these cliffs.
Scenes from Torna and Rajgad forts. Torna was the first major Sahyadri fort that we took an expedition to (left and right images). We returned a year later to explore the neighboring Rajgad (center image).
My personal interest in the Western Ghats was nurtured in the southern-most ranges and it took me several years to finally spend time in the hills and mountains that gave the Western Ghats their name. It is in the Sahyadris that dramatic traps, (i.e. ghats or steps) fall from the Deccan Plateau to the lower Konkan plains that border the Arabian Sea. This is an area with a fascinating geological history associated with the period of volcanism that created the Deccan Plateau and may be associated with the extinction of the dinosaurs (see links below).
During the three years that my wife and I were working at the Mahindra United World College of India I had a chance to get to know parts of the Sahyadris intimately. In 2002 when we started work the college was still relatively new and there was limited knowledge on campus about the hiking/outdoors opportunities in the area. Over my three years there I recruited a diverse collection of students, teachers and friends and set out to learn as much as possible about the landscape, ecology and culture of the Sahyadris. We used Harish Kapadia’s Trek the Sahyadris as a bible and followed it to as many of the nearby locations as we could.
Three different MUWCI hikes starting in Torna (top) in 2002 and continuing to Rajgad (2003) and Nane Ghat (2004). There are several distinguished faculty members seen here including Harendra Shukla, Karl Mossfeldt, Sandy Hartwiger, Anne Hardy, Andrew Mahlstedt and Beatrice Perez Santos. Students include Nicolas, Foong, Andree, Sadia, Tanya and several other wonderful hiking companions.
We first focused on the great and lesser-known Maratha forts(Tikona, Lohgad, Torna, Rajgad, Rajmachi, Harishchandragad, Ratangad etc.). Notable peaks near the campus were climbed, explored and camped on. Towards the end of my stay we started to explore the numerous Buddhist rock cut caves that the area is blessed with. I was a keen bird watcher but it was the Sahyadris where I was inspired to study and photograph the snakes and amphibians that we encountered (mostly on our campus, an din our home during the monsoon). Interactions with notable Pune naturalists like Ashok Captain, Vivek Gaur Broome, Ashish Kothari, Sunita Rao, Pankaj Sekhsaria, Reiner Hoerig, Erach Bharucha and others helped further my interest in the area. Through a fortuitous meeting with the state minister of education I was able to get a full set of Survey of India 1:50,000 and 1:25,000 maps of our Sahyadris area stretching from Nashik down to Mahabaleshwar for the college. As I had in the other areas of the Western Ghats, I worked to document the landscapes with medium format cameras, shooting mainly in black & white (see the High Range Photography album “Sahyadris“). I also shot color slide film (not scanned yet) and color print film on a small Olympus stylus. It’s these snapshots, originally scanned in Pune, that accompany this article.
Looking east over the Paud Valley showing the distinctive conical hill above the MUWCI campus taken from a high point that was known to students as Mt. Wilkinson (after the first MUWCI Head of School). This was taken in May after one of the first pre-monsoon showers. From February-May the hills experience fires set by grazers and farmers in the valleys. The landscape makes an amazing recovery in the monsoon months but the fire encourages deflected succession such that forests have a hard time recovering on open slopes.
The landscape of the Sahyadris is something special to behold and it changes dramatically between the dry, scorched months of the Indian summer (March-June) to the lush, verdant months of the monsoon (June-October). During my three years I worked hard to understand the nuances of the landscape and the monsoon’s impact on it. By my final year I was able to plan several trips that provided ideal lighting conditions to do justice to the landscapes.
The NASA/USGS Landsat program has given me a chance to rediscover the Sahyadris through their amazing archive of multi-spectral imagery that is now publicly available. The escarpment of the ghats was always impressive and something I tried to find the right light to do justice to. However, seen from air or space the Sahyadris are something else. The series of maps in this post are taken from a pass of Landsat on February 23rd 2014. A few days later I was in the area participating in a conference in Mumbai and I happened the tiles in Earth Explorer when I was looked to better reconnect with the Sahyadris after a 10-year gap. The tiles have taken a good deal of processing using ArcMap to get them into their current view. I have added place names of some of the notable places that we took MUWCI hikes to. There are quite a few other points (such as the Buddhist caves, Koyna Sanctuary etc.) that didn’t make it onto these versions of the maps. Nevertheless, they should be of interest to my former students, colleagues and other fascinated by the Sahyadris.
The culminating exploratory trek that I took with a MUWCI group was to the remote fortress at Ratangad. It overlooks a steep drop to the Konkan plains and has a spectacular view north to Kalsubai, the highest peak in the Sahyadris. We had a small group for this trip – Asia, Andree and a visiting math teacher from the UWC in Trieste. A year earlier I had been on an equally rewarding trip with colleagues Bill and his fiancée Richa. We camped at the breathtaking Konkan Kada with a group of some of the most wonderful MUWCI students, including Sadia, Tanya, Apoorv, Nicolas and several others.
REFERENCES
Kapadia, Harish. Trek the Sahyadris, 5th Edition. New Delhi: Indus Publishing Co. 2003. Print. Web Site.
Lockwood, Ian. “Sahyadris.” High Range Photography. 2005. Digital album on Web.
Lockwood, Ian. “Traversing the Sahyadris.” Sanctuary Asia. June 2005. Print (PDF).
Sheth, Hetu. “The Deccan: Beyond the Plumes Hypothesis.” Mantle Plumes. August 2006. Web.
MAPS
Sahyadris art ¼ : Showing the Malsej Ghats, Harishcandragad, Ratangad and Kalsubai sections of the Sahyadris.
Sahyadris Part 2/4: Showing Bhimashankar, Rajmachi and down to MUWCI.
Sahyadris Part ¾ : Showing the area from Lonavala and MUWCI down to Mahabaleshwar. This is the area that most MUWCI teachers and students became familiar with. Click on image for an A3 150 DPI version.
Sahyadris Part 4/4: Showing the area from Mahabaleshwar south to Koyna reservoir and lake. Mahabaleshwar is as far as we got during our time at MUWCI. Koyna is an important habitat for a range of wildlife including tigers, but it is under pressure from various development schemes and encroachment. Click on image for an A3 150 DPI version.
Land Cover Changes in the Palani Hills: A Preliminary Visual Assessment
1973 Landsat map of the High Range, Anaimalai and Palani Hills. (February 1973)
41 years later….Landsat view of the same area (February 2014)
I continue to be interested in themes of change in the southern Western Ghats (and Sri Lanka) and am now working to better measure and detect land cover change using Geographic Information Systems (GIS) and temporal satellite data gathered by the USGS/NASA Landsat satellites. My interest in the area has grown out of a deeply personal engagement with the landscape over the last few decades. It started on childhood walks with my parents, was excited by explorations with friends in school and then developed in more systematic photo-documentation trips as an adult. In recent years teaching and family commitments have kept me from visiting the field as much as I would like. My interest in using GIS as a tool for teaching and learning has brought me back in touch with the Western Ghats, but this time through the lenses and sensors of distant earth observing satellites. In the last year I have been working with the latest Landsat 8 imagery and am thoroughly impressed with the quality of the imagery that is now publically available. This has led me to look back through NASA’S archives to find old imagery to conduct change detection with. This post highlights preliminary comparison of Landsat mages from 1973 and 2014.
The maps included in this post look at the block of the southern Western Ghats just below the Palghat gap where significant features illustrate momentous changes in the landscape over the last forty years. Both sets of images were collected in February, a time of the year when it is dry and there are cloud free days in the southern Western Ghats. The first image, however, was taken 42 years before the 2nd and thus offers a unique opportunity to compare the land cover changes in these hill areas. My particular interest here is the western plateau of the Palani Hills. This is an area that many generations of KIS students know well from the hiking program that took us to places like Vembadi Peak, Berijam Lake, Vandarvu and the Ibex Cliff area. Starting in the 1960s and 70s these areas experienced intensive silviculture based on the earlier designation of montane grasslands being “wastelands.” Few KIS students and faculty members appreciated that they were witness to a radical ecological reworking of the landscape. The net result has been a significant change in the ecology and landscape of the area. Vast areas of the shola/grasslands systems in the Vembadi-Berijam-Vandaravu area have experienced significant changes.
It is a complicated mosaic of vegetation, ecosystems and issues that is now in place on the upper plateau of the Palani Hills. As the 2014 Landsat 8 image illustrates, most of the Vembadi-Berijam-Vandaravu area is covered by non-native tree plantations but there are important sholas that thrive between them. Several invasive species are spreading beyond plantation boundaries and threaten the remnant grasslands. In some areas shola species are regenerating in and amongst non-native plantation species. Some feel that this will eventually give way to mixed forests of shola species and dying plantations. Logging of planation species has been largely curtailed though there is a move afoot in the Forest Department to remove exotic species. Much of the upper plateau area is of limits because of forestry rules that have sought to limit the impact of tourists and agricultural communities in the reserve forest (RS) zone. A Kodaikanal National Park is in the pipeline and its notification and boundary lines are expected in the near future. Nevertheless, human communities are pushing into outer areas as the township of Kodaikanal and its satellite communities expand. Gaur (Bos gaurus) populations are on the rise, felt mostly in urban areas rather than remote areas!
Looking south over the 2,000 meter high Eravikulam plateau from Kattu Malai. The sunrise highlights the extensive “downs” of the shola/grasslands complex that is uniquely preserved in this magical National Park. Anai Mudi’s distinctive hat profile is on the right horizon while the edges of the Palalni Hills are on the far left. My father Merrick and cousin Anna are at the edge taking in an unforgettable Western Ghats experience.
One feature that has remained relatively constant has been the shola/grasslands mosaic that makes up Kerala’s Eravikulam National Park and Tamil Nadu’s Grasshills (part of the Anaimalais Tiger Reserve). Comparing both the 1973 and 2014 maps shows that these areas of montane grasslands, interspersed with sholas, have stayed roughly the same. This perhaps is no accident since Eravikulam and Grasshills have both enjoyed protection in the midst of the flurry of tree planting in the adjoining ranges. The grasslands show up particularly well and contrast with the neighboring shola vegetation. This is most likely the result of winter frost that has dried out much of the exposed grass (and thus is not photosynthesizing).
Eravikulam will feature in a series of upcoming posts tentatively entitled the High Range Diaries but I have included a few images from my visits and explorations of the area in the 1990s.
View of Anai-Mudi & the Eravikulam plateau from the east. Note how the lowland tropical rainforest has been cut back to make room for tea estates. Anai-Mudi is on the left and the sheer granite cliffs that protect the park are obvious. These same cliffs provide a home for the most secure population of Nilgiri tahr. This was taken with my friend Rahul Madura on an Enfield tour of the area. Scanned from two 35mm color negatives. (December 1994)
Pine plantation in the Palani Hills near to Poondi.
The classic tourist view: looking west over Berijam Lake from the fire tower view point. In this image, the arm of Mathikettan Shola is clearly distinguishable from the uniform, tall eucalyptus plantation (extreme left and right). These trees were planted on montane grasslands in the 1960s and 70s in a program to increase biomass for fuel and tanning purposes. With the existing Landsat imagery it is difficult to distinguish shola patches from such evergreen plantations. This makes accurate classification at this sale challenging. In the future, as the resolution of the satellite imagery improves, remotely sensed multi-spectral imagery should be able to make this distinction.
Index map for hill ranges of the southern Western Ghats using recent Landsat 8 multi spectral imagery.
FURTHER REFERENCES
Be sure to read Farshid Ahrestani’s article “To cut or not to cut” published by Conservation India last month. It looks at the dilemma of what to do with the huge amount of non-native tree plantation biomass in the Palanis and other Western Ghats ranges. We visited Eravikulam together, through the good offices of KN Chengappa and Tata Tea, in 1993 and continue to share a passion for conservation issues in the Palanis and neighboring ranges. One of ours tasks is to collect historical imagery of the hill ranges and use these to cross reference with contemporary imagery to illustrate change at a terrestrial level (as is done in his article).
For information about interpreting false color satellite imagery, see Hollis Riebeek’s excellent article on the Earth Observatory website.
SCHOLARLY (and TECHNICAL) ARTICLES
Amaranth, Giriraj et. al. “Diagnostic analysis of conservation zones using remote sensing and GIS techniques in wet evergreen forests of the Western Ghats – An ecological hotspot, Tamil Nadu, India.” Biodiversity and Conservation. 12. 2331-1359, 2003. Print.
Joshi, Kumar P.K. “Vegetation cover mapping in India using multi-temporal IRS Wide Field Sensor (WiFS) data.” Remote Sensing of Environment. Volume 103 Issue 2. 30 July 2006. Web.2 April 2014.
Menon, Shally and Kamal Bawa. “Applications of Geographic Information Systems, Remote-Sensing, and a Landscape Ecology Approach to Biodiversity Conservation in the Western Ghats. Current Science. 73.2 (1997): 134-145. Web. 30 March 2014.
Nagendra, Harini and Ghate Utkarsh. “ Landscape ecological planning through a multi-scale characterization of patterns: Studies in the Western Ghats, South India. Environmental Monitoring and Assessment. 2003. Web. 30 March 2014.
Nagi, Rajinder. “Using the Landsat image services to study land cover change over time.” ARCGIS Resources. 13 May 2011. Web.
Prakasam, C. “Land use and land cover change detection through remote sensing approach: A case study of Kodaikanal taluk, Tamil Nadu.” International Journal of Geomatics and Geosciences. Vol 1, No 2, 2010. Web. 30 March 2014.
Mumbai Revisited: An Appreciation for Innovation, Creativity & Resilience
A view of greater Mumbai (Bombay) using an image gathered by the NASA and USGS Landsat 8 satellite on Sunday February 23rd, 2014. Gray areas are built up urban parts of the megalopolis. There are significant areas of “green space” in Mumbai’s hinterlands as revealed by the image. These areas, such as Borovali National Park and several mangrove-laced estuaries show up as red and deep red in this false-color image. The satellite is picking up 11 different multi-spectral layers of data-most of which are not visible to the human eye. The 5,4,3 band combination emphasizes vegetation by assigning the infrared band to the color red while leaving green and blue with their normal bands. Other notable features include the Bandra Sea Link, Chhatrapati Shivaji airport, Elephanta Island and numerous ships in the ocean. Click on image to see enlarged A3 version at 150 DP
Back at ASB, after the morning visit to Elephanta, I enjoyed three invigoration days of thought- provoking demonstrations, workshops, lectures, interactions and talks at the ASB Unplugged. The workshops were crowded with 400 or so participants from across the globe and we were joined by the ASB staff, students and staff. The three days were split between student demonstrations, classroom visits and then “hands-on” learning institutes. The first day was capped with a Tedx talk.
There were many personal outcomes that I got out of the conference: I relished learning about strategies for effectively integrating technology in my classroom, interacting with students about their personal application of technology in the DP and CAS programs and sitting in on several excellent interactive lectures by learned experts. It was difficult trying to choose from the myriad workshops but my choices of Larry Rosen’s Brain-Based Learning workshop and Suzie Boss’ Project-Based learning were just right for my own needs. It was good being part of a whole school team approach and the six of us OSC participants regrouped frequently to share learning and outcomes from various workshops. Our family friend Alok Parashar is ASB’s head of administration and we reminiscing about our years together on MUWCI’s distant hilltop. Interestingly, there were no geo-spatial workshops on offer and it appears to me that this is a key deficiency in the program that will perhaps offer an opportunity to address at the next conference. Thinking about this, I started the download of a Landsat compressed file of Mumbai (taken just five days earlier) from Earth Explorer on the first night. It has taken several hours of processing and has helped me rediscover this neck of India that I know well from a decade ago. The image above is the outcome of that process. I have also started working with several other cloud free images from the Pune, Nashik and Ratnagiri areas.
ASB is an impressive learning community and they are blessed with outstanding resources. Like anyone in Mumbai and other urban areas in India they face a challenge in the day-to-day reminder of extreme income disparities in society-something there are few quick fixes for. Perhaps what is most interesting to me is their singular focus on their mission and purpose. The focus on innovation and creativity at all levels of the school is something that many of us could learn from. The space and time given for students and teachers to apply learning in practical ways was energizing. ASB’s Superintendent, Craig Johnson, passionately articulated this in his welcome and concluding speeches. These were positive ideas to bring back with us to Colombo. What they didn’t have in Mumbai was the greenery, fresh air, island hospitality, spicy sambol and quiet neighborhoods that are a blessing to the OSC community and it was with happiness that I returned to my family in the eastern suburbs of Sri Lanka’s capital city!
Scenes from a taxi window: the Bandra Sea Link, Banyan (Ficus benghalensis) growing on a Colaba buildings, and a Fiat on the newly opened Eastern Expressway.
REFERENCES
Future Forwards Exploring Frontiers in Education at the American School of Bombay. Mumbai: ASB, 2013. Web Link.
Riebeek, Holli. “Why is that Forest Red and that Cloud Blue? How to Interpret a False-Color Satellite Image.” NASA Earth Observatory. 4 March 2014. Web. 5 March 2014.
Sundarban Revealed: A Spatial Appreciation
Landsat View of Sundarban. Click on image for full A3 100 dpi version.
There is a forest at the northern end of the Bay of Bengal. It is a forest like no other and spread over a vast area where two of South Asia greatest rivers meet the sea after their long journey from the high Himalaya. The Sunderban is this vast, 10,000 square mangrove forest and it’s a place that in the 21st Century still embodies wilderness in its rawest, most beautiful and sometimes terrifying form. Political boundaries separate it between Bangladesh and India but once inside the maze of mangrove trees there are few signs of any human presence. The area hosts impressive plant and animal diversity and is well as one of the most secure locations for wild tigers to breed in.
For the last 40 years NASA satellite shave been imaging the Sunderban and the results have produced some of the most enigmatic images of the earth’s surface. With the Landsat data achieve now available for public use I have been exploring recent imagery from the Landsat 8 satellite. The data that I processed and displayed in the above image is very fresh- it was collected in late January and early February this year by Landsat 8. It’s given me a chance to virtually revisit a forest that was once a favorite place to go to for birding and photography expeditions.
Collage of 6×6 format black & white images from visits to the Sunderban in the late 1990s. Taken from my http://www.highrangephotography.com site.
FURTHER LINKS
Denzau, Gertrud et. al. Living with Tides and Tigers – The Sundarbans Mangrove Forest. Dhaka, 2009. Print. See Web link for book. This book is produced by the most authoritative people on the Bangladesh Sunderban. This include Rubaiyat and Elizabeth Mansur and their colleagues Dr. Gertrud Neumann-Denzau and Dr. Helmut Denzau. I had the privilege of interacting with them all on several memorable trips into the Sundarban.
Chakravortty, Somdatta. “Analysis of end member detection and subpixel classification algorithms on hyperspectral imagery for tropical mangrove species discrimination in the Sunderbans Delta, India.” Journal of Applied Remote Sensing. 7(1), August, 2013. Web.
Chowdhury, Biswajit Roy. The Sunderbans: A Photographic Field Guide. New Delhi: Rupa & Co., 2007. Biswajit is a good friend who published my early work on Nilgiri tahr in Environ magazine. He is involved in wildlife conservation matters from his base in Kolkata.
Kolkata Birds Lead by the energetic Sumit Sen there are excellent trip reports, images and resources on major birding sites in West Bengal and the North Eastern States.
Lockwood, Ian. “Bangladesh’s Declining Forest Habitat.” Sanctuary Asia. June 1998. Web. I wrote and photographed this with the idea of providing an overview of Bangladesh’s forest areas. The Sunderban features prominently in it.
Montgomery, Sy. Spell of the Tiger: Maneaters of the Sunderbans. New York: Houghton Mifflin 1995. Print.
NASA Earth Observatory. Sundarbans, Bangladesh. 15 October 2006. Web.
Sirajul Hussain Photography. (Facebook link) Siraj is an old friend who I exhibited with in Dhaka many years ago. He has some of the finest pictures of the Sunderban area.
The Guide Ltd. The best way to visit the Bangladesh Sunderban is with the family-run Guide Tours travel agency. Hasan Mansur and his family have been helping people to experience the Sunderban intimately for 20 or so years. I owe all of my best experiences there to them.
Note on etymology of Sundarban: there is some variation on the ways that Sunderban is spelt base on the source. The name can either be literally translated from Bengali as the “beautiful forest” or as a distinct name based on the dominant Sundari (Heritiera fomes) tree.
Explorations in Sri Lanka’s Dry Zone
Sigiriya from the south as seen from Pidruangala on a damp, monsoon-soaked morning.
In the last week of January OSC’s students and teachers fanned out across the length and breadth of Sri Lanka to learn outside to the traditional classroom walls. The focus of these trips was varied and encompassed a number of curricular goals, outdoor experiences, service opportunities and explorations of our host nation. There were a wide variety of transport methods: buses, vans, a flight north and even bicycles. Students explored ruins of past civilizations, surveyed coral life underwater, slept in tree houses, helped out in Tsunami-affected communities, sampled bird populations in a rainforest, tweeted about Jaffna’s recovery, abseiled off of waterfalls and much more. The outcome of students and teachers electrified by their learning was clear for all to see at the conclusion of the trips and has been evident as we reflect back on the experiences and learning.
This year aside from coordinating the program I led a small group of students on what I called an exploration of Sri Lanka’s dry zone ecosystems. I was supported by Marlene Fert and we had eleven Grade 10 & 11 students on the trip. My idea was to expose the group to sites that blend culture, history and ecology off the beaten tourist track. We were based in the shadow of the rock fortress at Sigiriya and port town of Trincomalee. Originally we had planned to visit Pigeon Island, but the stirred up seas from the tail end of the North East monsoon made this impossible. My family and I had made two trips in preparation for this study trip (see blog posts from April 2013 and October 2013) and I wanted to was provide a similar, yet climatically different WWW experience to the Sinharaja WWW trip. Ironically we experienced a good deal of rain in the dry zone, but never enough to negatively affect our plans.
Scenes from the dry zone int he wet season…Dehigaha Ela and Pidrangla
Back of Beyond’s properties at Dehigaha Ela and Pidruangala provided the perfect place to be based at. They are both situated in serene dry zone mixed evergreen and deciduous forests, they have super staff that provide a home-away-from-home atmosphere, the accommodation (some in trees or caves) is beautifully earthy and there is (thankfully) only intermittent cellphone connectivity! While there we took a day trip to Ritigala Strict Nature Reserve and a night walk in the Popham Arboretum. In Ritigala we explored the ruins of monastic communities and other evidence of past civilizations.
Biodiveristy, both living and dead, seen on our visit.
A highlight was visiting two archeological sites that both host important Buddhist vadatages (relic houses) and other significant sacred ruins. Medirigiriya is an impressive site with nearly two thousands years of recorded history. It sits off the main Habarana- Polonnaruwa road and is free of tourists. North of Trincomalee is the ancient Jaffna kingdom port of Thiriyai with a very old and important Buddhist vadatage set on a low hillock amidst mixed evergreen and deciduous dry zone forests. Thiriyai was apparently it is the “Thalakori in the 2nd century AD map of Ptolemy” (Wikipedia). Images from these sites will be highlighted in an album in the next post.
WWW Dry Zone Explorations map #1 (with edits)
Here is the poster (below) that I put together for the WWW exhibition held on 20th February 2014. The Landsat imagery is much more recent (from the week after the trips came back).
WWW Exhibition Poster (originally A1 size with 300 DPI)/ Reduced to 72 dpi here.
FURTHER LINKS
Dammika, Ven. S. Sacred Island: A Buddhist’s Pilgrims’ Guide to Sri Lanka. 2007. Web. 7 February 2014 (see Medirigiriya Thiriyai)
Fernando, Nihal et al. Stones of Eloquence: The Lithic Saga of Sri Lanka. Colombo: Studio Times, 2008. Print.
Lankapura http://lankapura.com/ (a good site for historical images & maps of Sri Lanka)
Raheem, Ismeeth. Archaeology & Photography – the early years 1868 -1880. Colombo: The National Trust of Sri Lanka, 2010. Print.
Using Remote Sensing Imagery for Teaching & Learning in the IB
Colombo Landsat#1 (5,4,3 “infrared” false color view)(27 June 2013)
Several developments in data accessibility and technology have helped launch a popular revolution in the use of remote sensing technology. The Landsat program run by NASA and the USGS has had a series of satellites orbing the earth since 1973 and has recently put its entire 40-year archive in the public domain. What this means is that students, teachers, scientists and citizens can now access detailed imagery of anywhere in the world to analyze vegetation, land cover and change. This has interesting implications for teachers and students in the International Baccalaureate Diploma program.
Remote Sensing (RS) and Geographic Information Systems (GIS) is not formally a part of any IB Diploma subjects. Anyone pursuing geography at the tertiary level will have to have GIS skills, but this has not been incorporated into the teaching requirements. The Geography, Environmental Systems & Societies and Physics courses, all have opportunities to use these technologies to address key concepts and learning outcomes. In DP Geography GIS is a useful tool in building geography skills (core 1.0) and the Urban Environments option. I teach basic GIS skills to all of our Geography students for them to use in the Internal Assessment as well as areas of the core syllabus (populations in transition etc.). We are also working in the OSC Humanities department to introduce basic GIS mapping skills at an early age. Despite GIS & RS only playing a minor role in the syllabus, they are showing up in final assessments. The May 2012 IBDP Geography exam question, for example, featured a Landsat image of urban growth and sprawl in the Pearl River delta taken from the NASA Earth Observatory.
Colombo from Landsat 8 (6,5,4 “false color”)(27 June 2013)
Colombo from Landsat 7 (2000)
Colombo Band combinations with Landsat 8
This year we have acquired two Vernier ALTA II Reflectance Spectrometers. I was exposed to the use of these while at the JOSTI workshops at Thomas Jefferson School for Science & Technology last summer. A highlight for me -and I was the only participant – was taking the Remote Sensing workshop with Lisa Wu and Shawn Stickler. They run courses in Geosystems and Oceanography which both utilize GIS and RS applications. Students at TJ are actively involved in the design and usage of their data gathering equipment. One of them had completed impressive work in the Chesapeake Bay interpreting temporal data using Landsat images combined with ground truthing trips.
The Alta II meters are relatively simple gadgets that measure the reflectance of different colors from a given surface. The meter operates by shining a small LED light (from Deep Blue up to Deep Red and Infrared). A photo sensor records the amount of light bouncing back into the meter. The value that the meter gives is then divided by the particular color’s wavelength (in nm) minus the “dark value” (value of meter when no color buttons are pushed). So it does take some simple division to actually arrive at the reflectance percentage once you have your readings. These can be graphed (see jack example blow) and then compared to standard values. I ran an initial trial using mango (Mangifera zeylanica) and jack (Artocarpus heterophyllus) tree leaves. The next week our Grade 12 students conducted a similar test on a variety of surfaces as a part of their IB Group IV project. Reflectance is quite consistent for various species but there would be variations based on the age of leaf (which is why I took values for two different jack tree leaves). NASA has a helpful online spectral calculator for looking at reflectance values of different species in North America.
What is interesting is to use the reflectance meter to corroborate or ground truth reflectance values of surfaces that are visible in the Landsat satellite imagery. The normalized differential vegetation index (NDVI) has also become a standard test run using RS images. It measures a value of vegetation in a given area and this can then be compared to the same area at other times. The Earth Observatory has a clear explanation of the NDVI index. India’s Aligarh Muslim University also has an excellent article on reflectance that is worth looking up. In the coming months my students and I will be working to make clear linkages between Landsat imagery and the values that they are collecting in our area.
Vernier Alta II Reflectance Spectrometer with different surfaces (the sensor is underneath and the value on the screen is for the “dark value”)
Reflectance readings from two jack fruit leaves (one old and one new).
OSC students collecting reflectance data on a traditional tile at the craft village, The above image shows the meter over a mango leaf. The value is a dark value (here with considerable light pollution from outside).
If you are looking to access the Landsat Program the best point to start is the USGS Earth Explorer (this is better achieved using a browser enabled with Java). Earth Explorer has a wide range of spatial data available and it is worth exploring all the many different data sets. Another point to access basic spatial data from Landsat (without having to process it) is the Terralook site. You can also use the Glovis Site (that I had recommended in my post a year ago). When I am working with Landsat data I download full GeoTif files from Earth Explorer and then work with the different tiles using ArcCatalog and ArcView (Desktop). Having a fast Internet connection is essential for this. I have started a page on my Mango Wiki site to help my students access Landsat data and instructions that are available online. A very useful manual to have is Remote Sensing for Ecology and Conservation authored by Ned Horning and several others at the Center for Biodiversity & Conservation at the American Museum of Natural History. For a portfolio of images taken from space and clear explanation of the way satellites gather multi spectral data see Andrew Johnston’s Earth From Space (Smithsonian National Air and Space Museum, 2007). The Alta II reflectance spectrometer meter is available through Vernier in the US and comes with a manual of lessons plans. It does not plug into the Lab Quest devices that most science labs are using.
Using Landsat Imagery in the Western Ghats & Sri Lanka Biodiversity Hotspot
Annotated map of the southern Western Ghats created on ArcMap
In the last six months I have been spending significant amounts of my free time learning about the Landsat program and how to access and analyze their 40-year archive of data, which is now freely available. I was initially motivated by several mosaics of remote sensing imagery that I saw at ATREE’s Ecoinformatics lab, the IWMI GIS lab and MIRSAC in Aizawl. Then earlier in the year I was gifted a copy of Remote Sensing for Ecology and Conservation through a program run by the Natural History Book Shop (NHBS) in London. The book is the result of collaboration between NASA and members of the Center for Biodiversity & Conservation at the American Museum of Natural History. It gives a very thorough overview of using satellite imagery in aid of conservation goals and has proven to be an indispensible aid in helping me understand the uses and applications of remote sensing. My interest is in applying the data and analytical techniques in areas of the Western Ghats and Sri Lanka that I have worked in, photographed, written about and taken students to.
In July the Landsat program celebrated 40 years of earth observation and analysis. They have made almost the entire archive of spatial data available to the public through the USGS Glovis site. I have started downloading some of the tiles with the goal of looking at temporal changes in vegetation and land use in areas in the southern Western Ghats and Sri Lanka. One approach is to use a photo editing software package (Adobe Photoshop etc.) to analyze the images but I have been interested in GIS and analytical applications of the imagery. Since most of my work with GIS is based on ESRI’s Arc platform of software it seemed sensible to use Arc Map and the Spatial Analysis extension to work with the imagery. However, if you are just starting off there are now freeware options available in software such as Q-GIS. The Indian government has made archival remote sensing imagery, including multi-spectral files, available on its Bhuvan site. I have not yet had time to explore these options and have been focused on trying to learn how to import, mosaic and analyze the NASA Landsat data through ESRI’s software.
For educators, curious people and novices such as myself the internet has provided an easy way to access and learn how to use and analyze remote sensing data. There is a wealth of online tutorial information available for using the Landsat archive. NASA, of course, has numerous links and a good place to start is the Landsat homepage. There are also other data portals such as ArcGIS Online, the University of Maryland’s Global Land Cover Facility and USGS’s Earth Resources Observation & Science (EROS). I am regularly updating my GIS Links page on my Mangotree teaching Wikisite with links to tutorials etc. on remote sensing, Landsat etc.
This Image of the High Range, Anaimalais and Palani Hills was taken by Landsat 1 in July 1973. Water bodies such as the Vaigai dam and larger reservoirs in the High Range and Anaimalais are prominent. Overall levels of vegetation are generally high presumably because of the onset of the South West Monsoon in the previous month. The significant feature in this image is how wide spread montane grasslands are! In subsequent years these were largely converted to commercial plantations of non- native tree species. The image awaits further analysis to make quantifications of various land uses and changes.
As aspect of the Landsat archive that fascinates me is the opportunity to do temporal studies of changes in land use in areas that I have first hand knowledge of. As is well documented, significant changes have happened in the land use in critical areas in the Western Ghats and Sri Lanka biodiversity hotspot in the last 40 years. Forest loss is perhaps what first comes to mind. But perhaps more difficult to track has been the change of forest cover or vegetation type. For example large swathes of high-altitude grasslands were converted in the 1970s and 1980s to fuelwood plantations of monoculture species. Eventually we should be able to do detailed studies of vegetation changes in critical hill ranges such as the Nilgiris, Palanis, Anaimalais and High Range using some of the tools that are available on modern GIS software.
Sinharaja Rainforest Landsat view highlighting the thermal band and closed canopy evergreen rainforest within its boundaries.
