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Four Band Multispectral Aerial Photography of Northern Thailand Watersheds.

Dr. Sathit Wacharakitti
Assistant Professor of Forestry and Remote Sensing,
Faculty of Forestry,
Bangkok 9, Thailand

Dr. Kaew Nualchawee
Assistant Professor of Computing and Remote Sensing Regional Computer Center,
Asian Regional Remote Sensing Center, Asian Institute of Technology,
P.O. Box 2754, Bangkok, Thailand


Naturally, airborne photography to be of maximum value for inventory purposes, because it possesses certain characteristics which will enable the greatest use and success in its interpretability. The multiband approach for airborne and spaceborne reconnaissance systems incorporates many of these necessary characteristics. This approach is based on the concept that unique photographic tones may only be resolved and identified by analysis of photos/or imagery which have been obtained in more than one spectral band. Moreover, multiband photography contains its practical advantage in providing greater amounts of information for use by the image analyst than would more commonly by available through conventional photographic missions

Northern Thailand watersheds are heavily deforested by shifting cultivators. This primitive slash and burn agriculture not caused only forest destruction but also ecological changes and environmental impact to highland and lowland area. Therefore, four band multispectral aerial photography project has been set up for taking the aerial photography of these watershed areas. Aerial photographs obtained from this mission are used land use classification and planning in the project areas.

Introduction

There are a number of hilltribes living in the significant watershed areas of northern Thailand. Most of these people practice shifting cultivation for their main source of income over the mountainous areas of the north. The primitive slash and burn agriculture not caused only forest destruction but also ecological changes and environmental impact to highland and lowland areas.

Because of the crucial importance of the northern highland areas as a watershed resource which affects much of the rest of the country, the special needs of the hilltribe people living in the area plus the cultivation of opium poppies, His Majesty the king has expended great effort t stimulate action in this vital area of the country. One example of such effort was the enhancement of the natural resource capability of the north as well as the promotion of the economic and social development of 350,000 hilltribe people living in Northern Thailand.

At present the Royal Norther Project covers 30 separate areas in several provinces in the north. In addition, there are a number of Government Departments and Agencies responsible for various activities in this region including the Royal Forest Department, Department of Public welfare, Office of Accerelated Rural Development, and Land Development Department. In November 4978, the Cabinet approved the Policy Guidelines for a Crop Replacement and Community Development effort which is coordinated by the Office of Narcotics Control Board. First priority is working in the Mae Chaem watershed and eventually this work will be extended into 5 other major watersheds and river basin areas in future years.

Because of the current as well as activities in the northern highlands, there is obvious need for a sound comprehensive survey of the area which is provided an accurate assessment of existing resources land use patterns and land capability and the extent of opium poppy cultivation to serve as a basis for future development work. Therefore, the Government of Thailand allocated the financial support for this purpose with the grant aid of 157,000 US dollars from UNDP for purchasing I2S Four Band Multispectral Camera, I2S Color Additive Viewer, Automatic Printer, Spectroradiometer, photographic films and other supplies. Therefore, the four band multispectral aerial photography project has been set up for taking the aerial photography of northern Thailand watersheds. Aerial photographs obtained from this mission are used for land use classification and land use planning in the project areas.

Objectives

The Fourth National Economic and Social Development Plan of the Royal Thai Government stresses the need to improve the management of basic resources and to rehabilitate environmental conditions. Particular emphasis is placed on the allocation and rehabilitation of land, forest and water resources to obtain maximum economic and social benefits with measures to be undertaken to check and limit the deterioration of these essential resources.

In line with the above national development goals, the project aims to achieve the following immediate objectives:
  1. To determine current land use patterns and land capability in 29 sub-watersheds of Northern Thailand, through the undertaking and photo-interpretation of an aerial photographic survey of the area using a four-band multispectral camera at a scale of 1:15,000.
  2. To provide the Government with detailed recommendations concerning appropriate future land use and land classification in the designated watershed areas.

      Aerial Photography Mission System

      After extensive consultations, both inside and outside the Royal Thai Government, it has been determined that a four-band multispectral camera is most appropriate to accomplish this purpose. Four –band I2S Multispectral Camera Mark I Model 500, with the focal length of 100mm was acquired, and Turbo Commander Model 690 A airplane was used for aerial photographic mission.

      This four-band multispectral aerial photography covering four bands of light spectrum including infrared, new and precise information can be gained on the natural resources of the areas such as soils, minerals, forest growth, water, agricultural crops and so on. In addition, through photo-interpretation, land use and land capability maps are complied which will allow for a national plan of action for developing highland areas. Besides these, this kind of aerial photography is linked with the LANDSAT Multispectral Scanning System. The utilization of both four-band multispectral aerial photos and satellite imagery are greatly beneficial to land use study and natural resource detection and classification.

      Location Of The Study Areas

      The aerial survey is flown by the Royal Thai Survey Department over the 6 major watershed; Mae Chaem, Mae Taeng, Mae Ngad, Mae Kok, Mae Ping and Mae Nan which approximately cover the area of 57, 100 sq.kilometers (covered 29 sub-watersheds) of upland and highland areas of Northern Thailand.

      The Project is started in November 1979, by taking the aerial photograph of Mae Chaem, Mae Taeng, Mae Ngad and part of the Mae Kok watershed areas. At present, 7000 four-band multispectral photographs area available to be used for study purposes of various fields. The project is ongoing and will be lasted in 1982.

      Photo-Interpretation And Land Use Map Compilation

      Photo-interpretation was performed on the four-band multispectral photographs of each sub-watershed or local project area. This photo-interpretation reports and map overlays are providing quantitative and qualitative information on the natural resources and land use in the designated areas. Ground surveys for data collection, such as forest productivity, land capability, socio-economic information, present use of land and so on was carried out in the areas being photographed with a view to facilitating subsequent photo-interpretation.

      Land use maps are complied on the overlays and detailed information concerning the areas and location of agricultural, forested and swidden areas are drawn and measured. Map overlays and detailed information on land capability and suitability for agriculture are also prepared.

      Moreover, land use planning and allocation of each project or sub-watershed area are designed by using factors of soils, elevation and slope, present use of land, socio-economic information and so on. Action field program is then implemented by applying these maps and information for local agricultural land and social-economic developments.

      Research and study of four-band structure characteristics in land use detection and classification are jointly carried out by the study team from National Research Council, Royal Forest Department, Land Development and Kasetsart University.

      Responsible Departments

      The four-band multispectral aerial photography of northern Thailand watersheds project is such a kind of integrated project that attempting to solve the problem on deforestation and simultaneously promote and improve social-economic of the normadic hilltribe people living on the high mountain. Therefore, there are several departments cooperated in this project; National Research Council is acting as the coordination agency with the aid of Royal Forest Department, Land Development Department, Agricultural Extension Department, Agricultural Economics Office, Mineral Resources Department, Royal Northern Development Project, Royal Thai Survey Department, Royal Thai Air Force, Chiang-Mae University and Kasetsart University. The project center is located at the Faculty of Forestry, Kasetsart University, Bangkok 9.

      References
      1. National Research Council, 1979. Aerial Survey of Northern Thailand Watersheds. A proposal submitted to UNDP National Research Council. 15 p.
      2. Wacharakitti, S. and K. Nualchawee, 1980. Four Band Multispectral Aerial Photography and Satellite Remote Sensing Technology in Land Use Planning. January 6-9, 1980. Chiangd-Mai, Thailand. 11 p.