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Mapping
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A Comparison between ERS-1, JERS-1, and Radarsat Satellite Radar Images for Mapping Tropical Deforestation
Yourif Ali Hussin Belinda Arunarwati Agus Wuryanta
The International Intitutue for Aerospace Survey
And Earth Sciences (ITC)
7500 AA Enschede, The Netherlands
Fax: (31)(53)4874-399
E-mail: HUSSING@ITC.NL
Abstract
Forest resources are important socially, economically and environmentally, especially tropical forests which are the home to at least two-third of the world organism, a number that amount slightly close to 3 million species. Indonesia is one of countries having large tropical forests after Brazil and Zaire. The major part of the Indonesian land surface, i.e., 143 million ha (75%), has the status of forest land. For the management of this vast area, up to data information such as land use land cover change is important. Data on land cover change and land degradation processes are needed for land use planning and development of sustainable land use management. The extraction of information on land applications including land use mapping and monitoring. According to the international sustainable forest management for timber production. That is why there is an urgent need for data on actual tropical forest extent and land cover change. Since 1989, the Indonesian Government (i.e. Ministry of Forestry) ahs been doing an inventory of forest using aerial photography, Landsat and Spot satellite data. However, the current method largely failed to acquire data on yearly basis because of sever cloud cover. The main objective of this research work was to compare between the SAR images of ERS-1, JERS-1 and Radarsat satellite in mapping forest cover types in an area of Central Sumatra, Indonesia.
1.Introduction
It is generally recognized that forest resources should be sustainable managed to support the need of present and future generations. The capability of the land to produce in sustainable basis is, in one way or another affected by the different objectives of different people/actors. An illustration of these complex objectives are: farmers want to develop the area for food crops, loggers want to fell tree for timber, and environmentalist want conservation and protection. For these reasons, the problems on deforestation and environmental degradation as a results of the activities of the former actors (farmers and loggers) are become alarming.
Deforestation can be expressed by the rate of change of forest cove area caused by changing use of forest land. This leads to different causes of forest land change which could be an indication of different types of deforestation. In most cases, deforestation is caused by expansion of agricultural activities and other land use practices such the logging activity. According to the FAO, more than 80 percent of deforestation is attributed to agricultural expansion. Logging indirectly contributes to this major cause of deforestation by providing access to farmer through the constructions of timber extraction roads.
Indonesia, a part of Malaysian botanical region, is the richest rain forest in the world. The major part of Indonesian land has the status of forest land i.e. 143 million hectares or more than 75% of total land. To manage that forest land in sustainable way, the Government of Indonesia instigated the Consensus of Forest Land use or TGHK (Tata Guna Hutan Kesepakatan). The problem of condition is needed urgently to supply the decision makers' objectives in order to support the forest management of Indonesia.
Remote sensing is an important data source of spatial data. Remote sensing system are divided its active sensors (use their own energy), and passive sensors (use natural energy; sun energy). Radar is an active sensor which transmits and receive a microwave signal. Some advantages of the use of radar in remote sensing are: radar can be used during both day and night, all weather capability (cloud cover, rain, fog, atmospheric dust, etc.), and its energy have the ability to penetrate through some surgical features. Radar is expected to be used for a wide range of applications in forestry, such as: activities in forest management and surveillance, monitoring of deforestation, shifting cultivation, colonization settlements, and use change.
Nowadays, GIS is recognized as an important tool to analyze the spatial data. The objective of data analysis is to extract useful information to support the decision makers' objectives. Data from different sources should be combined and comprehensively analyzed to achieve a tangible result, problem due to complexities of different actors objectives over a certain piece of land is an indispensable aspect of monitoring and detection of the extent of deforestation.
Deforestation within classified area of TGHK may create some problem. Not very classified area of TGHK is allowed to be replaced by some other land use. For instance, the deforestation caused by conversion to rubber estate is not allowed within the protection forest, but it is allowed within the conversion forest. The problem due to the lack of useful information about deforestation make worst situation. Then, the need of reliable information about deforestation within different forest land use (TGHK), such as location, extent and types of deforestation, are becoming obviously important in order to monitor the deforestation occurring in relation to the TGHK.
Most of tropical countries use satellite imagery as a data source f their forest information. Landsat TM and SPOT satellite images are the important source. Problems due to lack of quality image as result of cloud cover occur in the tropical forest area like Sumatra island in Indonesia (Sumatra is notorious area for cloud cover. This problem can be solved with the use of radar images as data source. Several reference mention that radar had been used as an effective tool for detection the particular pattern of human activity such as logging, agriculture expansion, (shifting cultivation) and illegal settlement in the tropical forest which resulted to deforestation. The problem now is how to use the radar to overcome al of the former problem.
Geographical Information System (GIS) are computer based systems that are used and manipulate geographic information. Normally geographical data (location and their attributes) are very complicated, so the need to stable system to handle these data is crucial. For instance, to very complicated, so the need of stable system to handle these data is crucial. For instance, to integrate the radar data as one source of spatial data with the field data or other former information. GIS approach will be used to established methods to integrate and analyze that kind of spatial data. However, until recently, the application of GIS using input of radar data to monitor deforestation types within the classified area of TGHK might be considered is still in its early development. Types within the classified area of TGHK might be considered is still in its early development. Hence, contribution to this development through a series of research, becomes obviously important.
The main objectives of this research paper were: to investigation the possibility to detect, differentiate, and classify deforestation and its types using satellite radar data; to assess the accuracy of detection with the classified area of TGHK (Consensus of forest land use in Indonesia).
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