| IRS Data Benefit Natural Resources Studies
The December 1995 launching of India's IRS-1C satellite has particular importance for forestry, agriculture and mineral specialists.
By Laura Lang On a per square kilometer basis, using remotely-sensed satellite data can be several orders of magnitude cheaper than using airborne imagery for mapping projects or mapping by foot, say experts. Because satellite data offers such a cost-effective approach, the U.S. Environmental Protection Agency is using data from India's IRS-1B satellite to identify and characterize environmental conditions in areas of southwest Colorado where natural resources are often damaged by contamination from abandoned or inactive mines, gravel mining and road construction and other activities. "The IRS data showed us the right study areas and has the right spectral bands available for vegetation classification," explains Jim Russell, a mineral specialist who worked on the EPA study throughout 1995.
In the EPA study Russell used four spectral bands of the IRS-1B, approximately equivalent to Thematic Mapper (TM) bands 1,2,3 and 4, with a spatial resolution of 36 meters and PC-based TERAVUE to create large-scale vegetation maps of the region. Generating HSI (Hue, Saturation, Intensity) transformed images from bands 4,3 and 1 produced the best classification results. Other techniques, such as the use of optimized RGB color images or Krosscolor images (a bi-spectral imaging and display technique used in TERAVUE), were also used.
The EPA study found the broad-scale remotely sensed data a useful tool for recognizing how individual activities like mining can compound to cause large-scale damage to a region's natural resources. Data from this project is being used to identify high-priority areas for focused evaluation.
Figures 2 and 3 target areas of agricultural uses shown as circles of center pivot irrigation from ground water and rectangles, furrow and flood irrigation from surface water. Any changes in irrigation patterns will be readily recognized on the satellite image. Qualitative changes in the near-stream, riparian vegetation indicate more wide-spread, basin-wide changes in the natural system. Road construction, urbanization, and rangeland management can result in either an increase or decrease in flow and sediment deposition. Vegetation changes and unstable hydrologic patterns can be correlated using remotely sensed images.
Additional research is being done with Digital Elevation Models and IRS data to associate vegetative communities with elevation, slope and aspect, says Russell. From Whence It Came
IRS data is captured by India's series of remote sensing satellites, the most recent of which, IRS-1C, was launched in December. India's orbiting IRS satellites are part of a constellation of eight presently planned by India's Department of Space (DOS) to provide a wide range of imagery over the next 10 years.
Meeting these goals will make India's constellation the world's largest serving the commercial market-a move setting the country's program apart from programs in France, Japan or the U.S. "India is emerging as an important source for viable satellite data. Their products are making the entire industry more competitive," explains Al Watkins, vice president of programs for EOSAT, the exclusive worldwide distributor of IRS data in Lanham, Md.
India's experimentation with remote sensing started in the late 1960s when its scientists used surveys taken with orbiting satellites launched by other countries for crop monitoring. Information from these surveys, obtained with infrared scanners, multispectral scanners, and radiometers, was backed by ground truth measurements, so regional and national planners could better evaluate crop yields, map soil salinity and alkalinity and monitor water pollution and deforestation.
In 1979, India took steps toward developing its own remote sensing program when, in cooperation with the U.S., it established a Landsat ground receiving station at the National Remote Sensing Agency in Hyderabad. The station became a training ground for the nation's scientists, who soon staffed the newly formed National Natural Resources Management System (NNRMS) and the Regional Remote Sensing Service Centres (RRSSCs). The country's scientists learned to interpret and analyze remotely sensing data in preparation for launching and operating their own satellites, Bhaskara 1 (1979) and Bhaskara 2 (1981).
The Bhaskara satellites carried a two-band TV camera system, one in visible and one in infrared, and a three-frequency passive microwave radiometer system. They offered a resolution of about 1 km. Data from these satellites was used to study resources relating to forestry, hydrology, large water bodies and geology. By the mid-1980s, India was well on its way to developing the India Remote Sensing (IRS) Satellite system, which continues to operate successfully and provide imagery to buyers worldwide. IRS-1A was launched in 1988, and an identical follow-on satellite, IRS-1B, was launched in 1991. Both satellites are equipped with sensors that acquire multispectral data with 36.25m and 72.5m spatial resolution. IRS-P2 was launched in 1994 with the same 36.25m sensor. The images from these satellites are comparable to ones obtained with the multispectral sensors on the French SPOT and American Landsat satellites, says EOSAT's Terry Lehman, director of applications and business development. Growing Room?
India's own domestic programs for sustainable resource development drive and support development of its satellite remote sensing program. Application centers located throughout the country receive and process imagery for a range of projects boosting productivity of farms, improving the supply of water to humans and managing forests.
With 903 million people, the country ranks second only to China among the world's most populous. To feed its population, more than 75 percent of India's workers engage in farming, generating about one-third of the value of the country's annual domestic product. However, the crop yield in India is one of the lowest in the world. Most farms are very small, and can be wiped out by drought or disease.
To help its farmers protect their fields of rice, wheat, sugarcane, cotton and jute (a plant byproduct used for weaving) and domesticated animals, India's national resource agencies use IRS satellite imagery to provide early warnings to farmers of diseases or drought conditions. Issuing bimonthly bulletins is proving extremely useful in drought management in the districts used for a drought-management pilot project last year; the capability is now being extended nationally. The imagery also helps the government predict crop acreage and yield estimates.
A national project to bring potable water to every village in India uses satellite imagery to locate underground water resources that could be tapped for local drinking water. Success rates with this approach are 88-95 percent compared to a 45 percent success rate using only conventional water-location procedures.
Another important application for satellite imagery in India is forestry management. Forests make up about 23 percent of India's land, but environmentalists say an optimal level would be 30 percent. Satellite imagery shows growing cities and farms have taken a toll. From 1974 to 1982 India's closed forest cover fell from 14 percent to 11 percent of the total land area. The Forest Survey of India now maps the country's forests on a biannual basis using IRS satellite imagery. These data help experts determine forest management plans to expand forest lands throughout the region and improve the health of individual stands used to produce commercial forestry by-products, such as charcoal, fruits and nuts, fibers, oils, gums, and resins.
Along with the shrinking of India's forests, satellite imagery shows the mushrooming urban sprawl. Land use maps have been developed for India's major cities, including Bombay, Calcutta, Madras and Ahmedabad for use by city planners. A specific example of satellite data being used for city planning was the recent survey for aligning the proposed ring road for the Bangalore Development Authority using satellite and ground-based data.
A national mapping project for land cover and land use using digital and visual surveying is underway to help the government balance the needs of farming, forestry and urban development. This project will map the entire country identifying 24 land use categories on a 1:250,000 scale. Future Directions
The progress of India's remote sensing satellite program indicates the country plans to remain at the forefront of providing commercial satellite imagery to users throughout the world, providing an alternative source for quality satellite data. India launched IRS-1C in late 1995, and plans are in the works to launch 1D in 1997. These satellites carry some of the highest resolution multispectral and panchromatic sensors to date. IRS-1C has a four-band multispectral scanner with a spatial resolution of approximately 23m, panchromatic sensors with spatial resolution of 6m, and a 780km Wide Field Sensor (WiFS) with a spatial resolution of 188m. Until this wide-field sensor, when people needed to look at a wide area, they used the Advanced Very High Resolution Radiometer (AVHRR) with a much lower resolution of 1km or 4km. In addition to improved spatial resolution, these satellites offer more frequent visits, stereo viewing and onboard recording capabilities.
The availability of data from IRS-1C and 1D, due to their inherently better resolution and infrared sensors, broadens the applications for using data in regional studies and abroad. For example, these sensors will provide information on water stress and pest infestation to improve India's agricultural management practices.
Other satellites from India, called the P Series (P2, P3, and P4), have payloads targeted to specific Earth observation needs, such as high-resolution sensors for cartographic applications, an ocean color instrument for oceanography and commercial fishing, and a specific payload to study the environment.
India is also extending the number of ground stations able to receive and process imagery from the IRS constellation through its agreement with U.S.-based EOSAT. EOSAT's ground facility in Norman, Okla., the same station collecting data from the U.S. Landsat satellites, was the first outside of India to receive IRS data in 1994. In 1995, EOSAT signed letters of intent for IRS reception in Europe, Japan, Australia and Thailand. Conversations are underway with several other ground stations to arrange for receiving, processing and archiving data, says the company.
EOSAT plans to incorporate portable ground stations to receive signals in other areas of the world. The advantage of these mobile units is they can be moved from region to region as required. In addition, tape recorders on 1C and 1D-a technical first for India's satellites-will save data captured over areas without an international ground reception station so worldwide imagery will be available. Broadening Their Reach
India's DOS is cooperating with international technology leaders in the private sector to make its IRS data more widely available. A 1995 agreement between EOSAT and Antrix Corp. Ltd. (India), the commercial marketing arm of India's DOS, provides for the commercial distribution of IRS data over the next 10 years. Under the agreement, EOSAT is the exclusive worldwide marketing agent for IRS data and will sell the data through its international data distribution network. Notes EOSAT's Watkins: "Partnerships like this-between government and industry-are helping the commercial remote sensing industry grow and better serve the needs of government and private users of this data." It will also ensure that product development, data pricing and availability will remain in sync with the needs of a growing market. About the Author:
Laura Lang is a freelance writer based in Ramona, Calif. She may be reached at 619-789-2989 (phone) or 619-789-5405 (fax). Back |
