INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 5, No 3, 2015

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1 INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 5, No 3, 2015 Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN Landuse/Landcover Mapping of Dhansiri (South) River Basin, Assam using Remote Sensing and GIS Plabita Barman, Dulal C.Goswami Department of Environmental Science, Gauhati University, Guwahati, Assam plabita.barman@gmail.com ABSTRACT Landuse/Landcover (LULC) mapping is an important input for planning, programming and implementing any land management activity. It is considered an essential element for modeling and understanding the earth as a system. This paper presents the landuse/landcover pattern of Dhansiri (south) River Basin of Assam. Multi temporal remote sensing data (LANDSAT ETM 1999 and IRS LISS III 2008) in GIS has been used to analyze and interpret the landuse/landcover changes between the years 1999 and The results show the pattern of change in landuse/landcover and the factors underlying it during the study period. The land use/land cover of the area has been classified into thirteen major types which are further categorized under five major groups. During the study period 1999 to 2008, significant area changes are observed in respect of agriculture and settlement landuse/landcover groups. Under agriculture landuse/landcover group, the area covered by agricultural land which mainly includes croplands has significantly decreased. These can be attributed to the increasing demand on land for settlement owing to growing population in the basin area. Keywords: Landuse, Landcover, GIS, Remote Sensing, Dhansiri River basin. 1. Introduction Knowledge of landuse and land cover is important for many planning and management activities and is considered an essential element for modeling and understanding the earth as a system. Land cover and land use maps are presently being developed from local to national to global scales. The term land cover is defined as observed physical features on the Earth s Surface. When an economic function is added to it, it becomes Land Use (FAO, 2005). Land is the most valuable natural resource on which all human activities are based. Land use/land cover (LULC) changes play a major role in the study of global change. Land use/landcover and human/natural modifications have largely resulted in deforestation, biodiversity loss, global warming and increase in natural disasters such as flooding (Reis 2008). Rapid land use/cover change is dynamic, widespread and an accelerating process, mainly driven by natural phenomena and anthropogenic activities, which in turn drive changes that impact humans (Mundia et al.2009). Information on landuse and landcover is therefore a prerequisite for planning, programming and implementing any natural resource management scheme. Landuse/ landcover inventories are assuming increasing importance in various resource sectors like agricultural planning, settlement surveys, environmental studies and operational planning. Its knowledge helps to bridge the gap in better understanding of relationship between cropland, forestland, settlement, wetlands etc. with the morphology of the river flowing through the area (Kotoky et al. 2012). Consequently, quantifying and understanding the extent and spatial distribution of LULC is of crucial importance to the study of environmental change at various scales (Phukan et al. 2013). Remote sensing and GIS has been proved to be an efficient tool for mapping and quantifying the spatial extent of Submitted on January 2015 published on February

2 landuse/ landcover for any area. The prerequisite for any resource management plan is a solid, dynamic, user friendly, spatial database. Application of remote sensing and GIS technology provides the solution in cost and time effective manner. 2. Study area Figure 1: Location Map of Dhansiri (South) River Basin, Assam The Dhansiri River Basin lies between latitudes N and N and longitudes E and E. The catchment area of the basin is approximately 10,305 sq.km. lying partly in the state of Assam and partly in Nagaland. The part of the river basin lying in Assam is considered for the present study (fig1).the part of the river basin that lies in Nagaland is covered by mountains and hill ranges, and partly by flat alluvial tract of the Brahmaputra Valley. The lower Dhansiri river basin comprises of unconsolidated sediments of Recent to sub- Recent age overlain by alluvial deposits of the Pleistocene age occurring along the foothills. The river basin falling within south-west monsoonal regime, receives a mean monsoon rainfall of mm and the average annual rainfall in the basin is mm. The monsoonal rainfall mainly concentrated mainly within a period of five months, usually from May to September, causes heavy landslides in the mountainous upper catchment areas and flash floods in the lower part of the basin. The total population in the Dhansiri watershed estimated as per 1991 census is 10, 24,733. Agriculture and forest comprise an important component under landuse in the watershed. 3. Material and methods Multi temporal Satellite images Landsat ETM 1999 and IRS LISS III 2008 were used for analyzing the landuse/landcover of the study area. Landsat ETM 1999 satellite data were downloaded from GLCF website and IRS LISS III satellite data from Bhuvan website. Classification of satellite images for generating thematic layers showing different landuse/landcover classes has been done using visual interpretation in ArcGIS 9.3 software. The different landuse/landcover patterns have been interpreted on the basis of texture, tone International Journal of Geomatics and Geosciences 475

3 and association. After interpretation and digitization of different landuse/landcover patterns of the area under study, attributes were added in the attribute tables of the respective thematic layers created for 1999 and 2008 satellite images. Attribute tables for two time periods were thus created to store the information such as area in square kilometers, name, and type of the various landuse/landcover categories etc. Area statistics of each landuse/land cover class were derived from these attributes tables. Ground checks were also made for confirmation of the results obtained for different land use characteristics. 4. Results and discussions The land use/land cover classes are evaluated from satellite imageries of 1999 and The landuse/landcover (lulc) classes have been classified into thirteen lulc types which have been grouped under five major landuse/landcover groups. Area calculation for each lulc type has been done using the calculate geometry tool in ArcGIS 9.3. The landuse/land cover map of 1999 is presented in fig.2 and the area under each lulc type is presented in table 1. Figure 2: Landuse/ Landcover Map of 1999 International Journal of Geomatics and Geosciences 476

4 Table 1: Landuse/Landcover Statistics of Landsat Imagery(1999) LULC LULC Class Area in Sq Km % of Total Area Group Agriculture Agricultural land Shifting cultivation Tea plantation Vegetated bar Forest Dense forest Open forest Degraded forest Settlement Rural settlement and homestead garden Urban settlement Industrial area Water body River Wetland Sandbar Sandbar The landuse/landcover map of 2008 is presented in fig.3 and the area under each lulc type is presented in table 2. Table 2: Landuse/Landcover Statistics of LISS III Imagery (2008) LULC Group Agriculture Area in Sq Km % of Total Area LULC Class Agricultural land Shifting cultivation Tea plantation Vegetated bar Dense forest International Journal of Geomatics and Geosciences 477

5 Forest Open forest Degraded forest Settlement Rural settlement and homestead garden Urban settlement Industrial area Water body River Wetland Sandbar Sandbar Figure 3: Landuse/Landcover Map of 2008 International Journal of Geomatics and Geosciences 478

6 The changes in the different landuse/landcover classes are also evaluated from the differences in the areas under each lulc classes for 1999 and 2008 thematic layers and the results presented in table3. Table 3: Changes in Landuse/Landcover Types of 2008 and 1999 LULC Group Agriculture LULC Class Area in Sq Km % of Total Change Area Sq.km % Agricultural land Shifting cultivation Tea plantation Vegetated bar Forest Dense forest Open forest Settlement Degraded forest Rural settlement and homestead garden Urban settlement Industrial area Water body River Wetland Sandbar Sandbar It has been observed from table 3 that areas under agricultural land have decreased from 19.43% in 1999 to 16.83% in This can be related to an increase in area under rural settlement and homestead garden and urban settlement from 15.33% and 0.27% in 1999 to International Journal of Geomatics and Geosciences 479

7 20.57% and 0.41% in 2008 respectively. The area under wetland class also shows a reduction from 0.68% in 1999 to 0.60 % in Though the change in area is negligible, however it can also be attributed to increase of settlement area in Area under tea gardens shows a positive change from 2.88% in 1999 to 3.05% in Tea is an important economic commodity and therefore a good sign from the point of view of economic development in the river basin. Since a part of the river basin lies in the hilly region, shifting cultivation is a major agricultural practice in the hilly terrain. For the Dhansiri river basin the area under shifting cultivation has been found to increase from 2.28% in 1999 to 3.3% in In the river basin the reserve forests found namely are Diphu, Dayang, Nambor and Rengma. A part of Kaziranga National Park also falls in the river basin. The areas under dense forest and open forest show decline from 50.74% and 5.59 % in 1999 to 46.73% and 4.78% in 2008 respectively. The area under degraded forest shows a positive change from 1.62% in 1999 to 2.25% in This shows that forest land degradation is taking place in the river basin to meet the needs of growing population for settlement and food production in the form of shifting cultivation. Thus decrease in forest area demands immediate attention of the concerned authorities as forests provide habitat for wild flora and fauna of that river basin. Water is one of the most indispensable natural resources. Waterbodies here include wetlands and rivers. Waterbodies covered only 0.81 % of the total area in the year 1999 which further decreased to 0.74% in The probable reason for this may be due to natural seasonal and annual variations coupled with the impact of prevailing unscientific landuse practices.. The area covered by sand bars in the lower part of the river is found to be almost same in both the surveyed years, namely 0.13% in 1999 and 0.14% in Conclusion Natural as well as socio-economic factors affect the land use/land cover pattern of a region. Increasing population and the growing demand for agricultural products is putting great pressure on land. Hence land is becoming a scarce commodity nowadays. Therefore information on land use/land cover and possibilities for their optimal use is essential for the selection, planning and implementation of land use schemes to meet the increasing demands for basic human needs and welfare (Uma et al. 2011). Using remote sensing data of 1999 and 2008 incorporated in GIS domain, landuse/landcover classes were evaluated for these years and changes that had occurred were detected. Thirteen major landuse/landcover classes have been identified in the river basin. During the period between 1999 and 2008, significant area change has been observed in agriculture and settlement landuse/landcover groups. Under agriculture landuse/landcover group, area in agricultural land which mainly includes croplands has significantly decreased. These can be attributed to demand in land for settlement owing increase in population in the basin area. The area under shifting cultivation shows a rising trend. This practice is the major cause of deforestation in the basin which is clear from the observed data showing decreased area under dense forest and open forest during the period of study. The area under degraded forest has increased which means that more and more forest lands have been cleared to bring under shifting cultivation and unplanned settlement. Thus the Dhansiri(S) river basin is under the grip of problems of deforestation and land degradation. One of the major causes of these land degradation and deforestation is shifting cultivation that has been practiced by the hill tribes of this region and increasing population growth. Shifting cultivation practice results in soil erosion and flood problems on the lower International Journal of Geomatics and Geosciences 480

8 reaches of the basin. Some of the important locations through which the Dhansiri River flows include the Dayang Reserve Forest, Garampani Wildlife Sanctuary, Nambor Reserve Forest and finally the Kaziranga National Park close to its confluence point with River Brahmaputra at Dhansirimukh in Golaghat district of Assam. 6. References 1. Kotoky P., Dutta M.K. and Borah G.C., (2012), Changes in land use and land cover along the Dhansiri river channel, Assam - A Remote Sensing and GIS approach, Journal Geological Survey of India, 79, pp Mundia Charles Ndegwa and MurayamaYuji, (2009), Analysis of Land Use/Cover Changes and Animal Population Dynamics in a Wildlife Sanctuary in East Africa, Remote Sensing, 1, pp ; doi: /rs Phukan P., Thakuriah G. and Saikia R, (2013), Land use Land Cover Change Detection Using Remote Sensing and GIS - A Case Study of Golaghat District of Assam, India, International Research Journal of Earth Sciences, 1(1), pp Reis Selçuk, (2008), Analyzing Land Use/Land Cover Changes Using Remote Sensing and GIS in Rize, North-East Turkey, Sensors, DOI: /s Uma J. and Mahalingam B., (2011), Spatio-Temporal and Landcover changes of Land use analysis using Remote Sensing and GIS: A case study of Kanchipuram District Coastal Stretch Tamil Nadu, International Journal of Geomatics and Geosciences, 2, pp International Journal of Geomatics and Geosciences 481