A look at remote sensing Its use in Nepal

SUVECHA PANT

The term "remote sensing" is now commonly used to describe the science of identifying, observing and measuring an object without coming into direct contact with it. Remote sensing technology began with the invention of the camera more than 150 years ago.

The idea and practice of looking down at the Earth’s surface emerged in the 1840s when pictures were taken from cameras secured to tethered balloons for purpose of topographic mapping. However, on a global scale, digital cartography or computer-assisted cartography came into existence in 1964 – which revolutionised modern remote sensing methods. Similarly, the research on Geographic Information Systems (GIS) started in the early sixties.

In Nepal, remote sensing was first used when the first aerial photograph of Sagarmatha was taken in 1933. For the last three decades, aerial photographs have been used for mapping and monitoring of natural resources.

The technology of remote sensing has great potential applications in Nepal since 80 percent of the total area is mountainous, characterised by difficult working conditions, inaccessibility and general scarcity of accurate maps. More than 50 percent of the land is used for agricultural production; the main economy of the rural people being agricultural based. During the last two decades, Nepal has relentlessly pursed an ambitious space technology programme of using satellite remote sensing (RS), GIS, Global Positioning Systems (GPS). Keeping with this outlook, in December 1984, the fifth Asian Conference on Remote Sensing (ACRS) was held in Kathmandu. Similarly, this year in November the twenty-third ACRS was also organised in Kathmandu bringing together experts from across the globe.

HMG, realising the importance of the technology for natural resource information extraction established the National Remote Sensing Centre (NRSC) in 1981. It was the first institution to apply efficient methods for identifying, classifying, monitoring and evaluating renewable resources of the country for all round development.

Since the existence of NRSC, achievements made were:

1) Marshyandi watershed study for the possibility of hydropower development

2) Terai deforestation study for sustainable development of Terai forests

3) Study of natural resources of Gulmi district

4) Crop yield forecasting of Bhakatpur district

5) Hydrological and geological mapping of Bagmati watershed

6) Estimation of national forest areas

7) Snow line survey and run off prediction

NRSC was merged in 1989 with the Forest Survey Division (FSD) of Forest Research and Survey Centre (FORESC) under the Ministry of Forest and Soil Conservation (MFSC) along with the Remote Sensing Section (RSS). At present, the main activity of FSD is to collect forest resource data using conventional as well as modern space technology (GIS/RS/GPS) and to provide information to the division/agencies under the MFSC for sustainable management and development of forest resources in Nepal. FSD is actively involved in a research project entitled "Himalayan deforestation and its impact on the atmospheric environment".

The overall objective of FSD is to provide information about forest resources in Nepal for improved decision-making, economically and environmentally sustainable use of forests. In the last few years, FSD has completed the following activities:

1) Study of Terai Forest Resources, using satellite data of 1991, aerial photos of 1990 and existing maps

2) Deforestation of 20 Terai districts from 1978 to 1991

3) Region-wise vegetation maps of the country

4) Study of detailed forest resources of Palpa, Nawal Parasi, Rupandehi, Kapilbastu, Makawanpur, Udaypur, Chitwanm and Dhankuta.

In 1989, the Asian Development Bank (ADB) provided technical assistance to the International Centre for Integrated Mountain Development (ICIMOD) for establishing a Mountain Environment and Natural Resources Information System (MENRIS), serving as a resource centre and application for the GIS/RS/GPS technology in eight member countries of the HKH (Hindu Kush Himalayas) Region. MENRIS has established an Environment and Information Assessment (EIA) unit within the MFSC. The EIA unit is also conducting a "Spatial framework for Kathmandu Valley" to develop a digital database on the Kathmandu Valley and assess the current environmental situation. The aim of the project is to prepare the baseline data using topographical maps, aerial photographs, cadastral survey data, satellite images, census surveys, socio economic surveys and other relevant information. The basic data layers will be elevation, drainage, geology, soils, settlements, land-use, different infrastructures and political boundaries.

Presently ICIMOD is using the GIS/RS/GPS technology in Bhutan, China, India and Nepal to revise land-use maps. In these countries, areas where land degradation is acute have been identified and assessed. In Nepal, ICIMOD has given special importance to research analysis of land use patterns, as agricultural land of high quality is scarce in the country. It has prepared land suitability maps of Nepal based on soil type, rainfall, temperature, altitude, and growing period. Areas with potential for growing rice and wheat are ranked according to their suitability. It has also prepared large-scale forest cover maps of the eastern part of the country, using aerial photographs combined with satellite data. The melting of snow and its impact on the flow of related river waters have also been studied using satellites.

The ICIMOD satellite research study of the Himalayas has found that snowmelt is one of the most complex phenomenon in the field of hydrology. Snow-covered watersheds in the Himalayas are very large, varying from about 610 to 6100 meters at altitudes from 2000 to 7000 meters and above. Snow depths vary widely, from a few centimetres to several metres within short distances.

RS/GIS/GPS technologies are essential and urgently needed for sustainable development and the proper utilisation of natural resources in Nepal. Remote sensing technology has made the earth a smaller place and lands that could never be explored due to inaccessibility can be now seen with great precision. It is certain that remote sensing is a technology that will prove to be valuable, and although Nepal has made some progress in its utilisation, it is yet to fully reap its benefits.

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