Monitoring Land Use and Land Cover Changes in a Part of Central Himalaya-Contribution towards Regional and Global Environmental Study

D.P. Semwal and P. Pardha Saradhi
Department of Environmental Biology,
University of Delhi, India

Abstract

Anthopogenic activities in natural systems have resulted in large-scale changes in structure,composition and spatial distribution of vegetation patterns. The land use and cover change (LUCC) study under the International Geosphere Biosphere Program (IGBP) has taken many initiative in above context. Remote sensing data efficiently provides detailed information regarding forest cover,vegetation type and land use/land cover changes on regional scale. These were analyzed using Survey of India Topographical Map (1966), IRS-1A (1990) satellite data and ground truthing of study area (2001-2003) for a part of Okhimath Block, Garhwal Himalaya. The land use/land cover map were prepared in order to study land cover dynamics using large scale (1:50,000) map. Supervised and un supervised classification procedure adopted for digital classification satellite data. The results shows that forest records about 63% of the geographical area in which broad leaves/oak forests (25%) dominate the scene in 1996 while in 1990 satellite data having 22 per cent. It is followed by agriculture/settlement having 22% in 1996 and 24.5 per cent in 1990. The loss of vegetation cover was estimated to be 12.42 per cent approximately during 25 years. The investigations have provided an input to land hydrology and watershed based monitoring of the Himalayan region. The study also contributes towards solving global issues as there exists upstream-downstream relationship between the Himalaya and the Bay of Bengal.

Introduction

Huge pressure of growing population,increased demand for food, fuelwood and shelter combined with industrial activities have essentially led to drastic change in land use/land cover patterns. Information on existing land use/land cover, its spatial distribution and change are essential prerequisite for planning (Dhinwa et al., 1992) Land use planning and land management strategieshold key for development of any region (Anon, 1992). Land use data are needed in the analysisi of environmental process and problems that must be understood if living condition and standards are to be improved or remained at current level (Anderson et al., 1976). Space technology has emerged as an efficient and powerfool tool in providing reliable information on various natural resources of a region in a spatial format. Such spatial format is essential for planning (Roy et al., 1991, Joshi, et al., 2001). In the present study area, the degradation of land due to overgrazing/cutting, landslide etc. has been studied for both qualitative and quantitative features of different forest category Semwal and Bhatta (1994).

Remote Sensing tehchnology can play a vital role in providing accurate and reliable landscape detail with lower cost and lesser time compared to other methods. In the present study, IRS 1A digital data were used to delineate existing land use/land cover types for 1990 satellite data. The land use/land cover type maps were used ti study the environment change monitoring pattern and impact due to antrophogenic activity in a part of central Himalaya.

Vegetation covers monitoring using Remote Sensing Data

A better knowledge about forest implies information about their potential extension, composition and evaluation, including notably their rate of transformation to other uses. National inventories of appropriate design can provide such information. Resulting database should be periodically updated by adequate qualitative monitoring system.

There is a need to obtain reliable data about vegetation resources at regional and microlevel as well, which would help in planning forest management strategy for sustained yield and benefit for society. Ground surveys serving such end can be tedious and infrequent. A new tool for synoptic surveys is essential.

Satellite remote sensing is a timely technological development in view of serious pressures on natural resources. Launching of LANDSAT-1 bay NASA (USA) marked the beginning of satellite based remote sensing. Subsequent milestones were marked by improvement in spatial and spectral resolution in LANDSAT-TM, SPOT of France, IRS-1A, B, C, and D of India. Special resolution provided scope to identify vegetation types with subtle spectral differences, the increased spatial resolution enhanced mapping capabilities on larger scale i.e., upto 1:50,000 scale on case of LANDSAT-TM and IRS-1A and 1:25,000 using SPOT-1. taking optical remote sensing data in temperate region is constrained by perpetual cloud cover. Microwave remote sensing with the ability to penetrate cloud is promising. Programmes of European Space Agency (ERS-1), Canada (RADARSAT) and US (Shuttle Imaging Radar experiments) have proved their potential in catering to this need. [Burns G.S. and Joyce A T (1982), Estates J E, Stow D and Jenson J R (1982), Jensen J R (1986)].

Study Area

Location: The study area lies in the hilly country of District Rudraprayag. The whole area falls between 30o 30’-30o 45’N Latitude and 79o 0’-79o15’E Longitude and covers an area of about 700sq.km. (Fig.1). the altitude ranges from 1200m to 3500m (Kedarnath Peak). The present study area consist most part of the Kedarnath Wild Life Sanctuary and adjacent conservation areas of Ukhimath Block, located in Rudraprayag district of Uttranchal. The study is well known for its floral and faunal diversity, important for a large number of rare and threatened species. The study area is bounded by Madhamaheshwar river in the east, Mandakini river in the west, alpine region of chamoli district in the north and Augustmuni block in the south. The study area is shown in figure 1.

Geology: the central sector of the Himalaya comprising Nepal, Kumaon and Garhwal is collectively reffered as Central Himalaya. Thus, Indian Central Himalaya extends from the Kali river in east separating Nepal and Tons Bhabhar valley in the west separating it from the North West Himalayan sector. The whole region comprises of five well defined physiographic belts, each being a distinct geological unit. These belts from south to north are identified as: Tarai and Bhabhar; The Siwaliks; The Lesser Himalaya; The Graet Himalaya and the Tethys and Tibetan Himalaya. The various lithounits i.e., purple slates, lime stones, conglomerate and quarzites are involved in the formation of the Lesser and Great Himalayan belt. By the study of sedimentary structures, stratigraphic setup and the various lithounits, it has been concluded that these rocks were deep marine to shallow marine in nature.

Soil type: Soil is a product of geological, chemical, biological and cultural interactions. The soils of this region vary according to aspect, altitude and climate. On the whoel soils of the Himalaya are young and thin. However, generally the soil is hill soil type (Raychoudhary, 1963) which is dark brown to brown at surface and brown to yellowish brown in the sub soil in nature and endodynomorphic.

Materials and Methods

Material: Survey of India Topographical Map in the scale of 1:50,000 were visually analysed/ interpreted. Base map of the study area were also consulted for ground truthing, on-screen visual interpretation and digital classification of satellite data. The computer system Windows 2000 and GIS Software ERDAS used for land use/land cover and forest types mapping.

Methodology: The work was divided into following distinct phases

Prefield: The base map showing drainage, roads, towns, and villages was prepared from the Survey of India topographical map. This phase conisted of delineation of land use/land cover types based on tonal and textural variation on the map which will later on help in identification of land uses features in 1990 satellite data. These major details have facilitated to match the features on the satellite images while classifying or interpreting them visually/digitally.

Preliminary Interpretation: A base map was prepared extracting its boundary from the Survey of India, topographical map at 1:50,000 scale showing important features. The boundaries of the forest vegetation within the extent of the study area were traced to prepare different themes. Visual interpretation technique was used to study existing topographical map on the basis of image characteristics. This technique was chosen to avoid problems of mis-classification of different land use/ land cover categories. The map feature were interpreted for land use classification using appropriate interpretation keys (Table 1) to enable direct comparison and detect change over a period.

Field Work: Reconnaissance visit in the study area has been made to acquaint, with the landscape. Relationship between ground features and their respective image/map elements were identified in satellite imagery. During the fieldwork sample plots were laid down in different vegetation types occurred in different altitude, aspect and site conditions. The sample plots were also selected on the basis of the degree of interferences of human activities surrounding the deforested area.

Post Field: The interpretation key was developed on the basis of tone, texture, pattern, association, location, shape, size and contours. The visual interpretation of Survey of India Topographical Map (1966) was carrier out, using the interpretation key (Table 1). The area of each land use category was measured using Tamaya Digitizing Area-Line Meter (PLANIX 5000).

The thematic maps generated from both SOI topographic maps and IRS 1A satellite data were imported, geo-referenced, digitized in GIS environment. Then the spatial and temporal analyses were done in the GIS environment for mapping, recognizing and evaluating the environment charges in the land use/land cover area through Overlay method/analysis. The methodology adopted in the present study is illustrated in the flow chart (Fig.2).

Results and Discussion

Area under major Land use/land cover categories was calculated for the year 1966 and 1990 (Fig. 3a and 3b). Forest areas have been categorized into three classes viz., Pine/Conifer, Broad leave/oak and scrub/alpine meadows. This information is extracted from 1966 and 1990 satellite imagery. Non-forest land includes agricultural land, barren land, habitation, water bodies and snow cover areas (Plate 1a & 1b). Around 12.42 percent of the total area has changed showing overall increase in agriculture/settlements; scrubland and show cover area. This was occurred at the cost of Conifer and Oak forest.

Changes in Forest cover: Forest area has decreased by 6.00percent of the study area; it is probably due to deforestation. Deforestation has arisen due to four principal causes, often in relationship with each other: excessive felling of trees for timber, fodder fire and clearance of land for agriculture/settlement area. Forest areas are mainly shifted towards agriculture and scrub/alpine meadows areas. Almost 4.00 percent of conifer forest area has converted into agriculture area is due to high commercial value of pine species. Another 1.15 percent of the forested land changed into scrub/alpine meadows area due increase in population and far fulfilling ever-increasing demand for food, fiber and shelter.

Changes in Agriculture land: A major factor responsible for the increase in agriculture land bas been the search of new agriculture/settlements sites, it is due to increasing population pressure. The forest land has decreased from 39.99 percent in 1966 to 33.99 percent in 1990 at the cost of increase in, agricultural/ settlements, scrub land and snow/cloud cover.

Changes in Scrub/alpine meadows: Significant (1.15 percent) increase was noticed in the area under scrub and alpine meadows. This is because of the cutting of Pine and Broadleaved forest. With increasing human pressure on land, the intensive felling has extended even those areas, which are under ecological stress leading to accelerated soil erosion and excessive land degradation.

Conclusion

The changes in land use/land cover were inferred from the differences between 1966 and 1990 status. Forestedland has decreased significantly due to land acquisition (For agricultural/settlements) by local people. Density of vegetation has decrease due to human interference and improper management by Forest Department. Agricultural/settlement areas have also increased at the expense of forestedland. Study has revealed that combine use of Survey of India toposheets, ground data and remotely sensed data could be conveniently used to detect the changes in land use/land cover. However, the accuracy of results depends on the individual accuracy level of the two different data sources and interpretation.

Acknowledgement

The first author is grateful to CSIR, HRDG, and Govt. of India for financial support in the form of Pool officer ship (SRA). I am thankful to all staff members of Pool Section of CSIR for their kind cooperation during the tenure.

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