1.1. Background

UNEP Environment Assessment Programme for Asia and the Pacific (UNEP/EAP-AP) has been involving in the macro scale land cover assessment and monitoring of selected countries in the Asia-Pacific region. The prime goal of the ongoing Land Cover Assessment and Monitoring Project is to prepare a wall-to-wall map of the region and to monitor the changes across time. In the first phase, major land cover types at a scale of 1: 1 million were identified and monitored by using time series NOAA AVHRR 1 km resolution data. Until now, the project has completed analysis of twelve countries in South and South- east Asia including Bangladesh, Cambodia, I.R. Iran, Lao P.D.R., Malaysia, Mongolia, Myanmar, Nepal, Pakistan, Philippines, Thailand and Vietnam. The study aims to produce reliable and harmonized land cover data, utilizing same classification system, same methodology and same data sources for all the countries in the region.

The second part of the Land Cover Assessment and Monitoring Project is to identify areas undergoing major land cover transformations (called "hot spots") and investigate those areas in detail by using high resolution satellite data such as, SPOT, Landsat, IRS, etc. With the help of high-resolution satellite data, it is possible to identify the nature and extent of land cover transformations in greater detail. The driving forces responsible for the changes can also be identified. The use of remote sensing technology for providing such an information, in a regular basis helps policy makers and planners to formulate effective land use planning for sustainable development based on informed decision making.

Through monitoring, three 'hot spot' areas such as Oudomxay province in Northern Laos, Mekong Delta in Southern Vietnam and Loei province in Northern Thailand were identified for detailed investigation. In case of Oudomxay province, the prime objective was to investigate in detail the pattern and magnification of shifting cultivation activities and their change behavior relating with bio-physical and socio-economic variables of the province. In case of Mekong Delta, the principal objective was to investigate in detail, how agricultural practices such as cropping pattern, cropping intensity, crop types, etc. are changing during the recent past. In case of Loei province, the objective was to investigate in detail how forest lands are converting to other land use types such as crop lands, orchards, commercial plantations, etc.

The output of the project contributes and fits in the overall framework of environmental assessment of UNEP/EAP-AP (Fig. 1.1), the ultimate goal of which is to help formulate appropriate legislation and action plans.

(Source: Surendra Shrestha, UNEP/EAP-AP )

1.2. Rationale of the Project

Uncontrolled land cover transformation is one of the major environmental problems in the Asia and Pacific region. Conversion of forests to other land uses is the major type of land cover transformation in the region. Timely and accurate information of such transformation is vital for global change monitoring, resource allocation at the national/international level and also for the informed decision making. This ultimately contributes towards the ecologically sustainable development of the region.

NOAA AVHRR data was found to be very useful for the assessment and monitoring land cover transformation at a macro scale for the twelve Asian countries explained earlier. The harmonization of land cover categories was adopted in the interpretation of satellite data necessary for a comprehensive regional resource assessment and information aggregation. Major land cover types were enumerated as evergreen forest, deciduous forest, mangrove forest, scrubs land, agricultural land, and water bodies. Site specific land categories like marshlands along the Mekong Delta in Vietnam and variations among agricultural practices in Bangladesh were separately noted.

In the process of monitoring land cover dynamics, it was ascertained that shifting cultivation continues to play a dominant role in forest type conversion among the countries being investigated under this exercise. The typical transformation from one type of vegetation to another, especially in the increasing proportion of open woodlands and dry deciduous group from the original evergreen or semi-evergreen type is apparent. Yet, the expansion of originally recognized scrub land that denotes mostly the presence of crop cultivation became the main feature of land degradation. Intensification and diversification of agricultural practices is also prominent in the region.

Such macro-scale landscape modifications as discerned in the time series analysis of AVHRR data subsequently lead to increased attention for a deeper investigation of the area. With the analysis of 1985-1986 and 1992-1993 NOAA AVHRR 1 km resolution satellite data, three "hot spot" areas were identified in three Asian countries (Oudomxay province in Northern Laos, Mekong Delta in Southern Vietnam and Loei province in Northern Thailand).

The prime objective of this exercise is to investigate in detail the pattern and magnification of land use conversion, their change behavior and relating the change with bio-physical and socio-economic variables of the area. The use of high resolution satellite data and other forms of field information are being contained in this second phase of the overall Land Cover Assessment and Monitoring Project activities. The output of this exercise intends to serve as an early warning system for preventive measures in such areas exhibiting major land transformation or active deforestation. The general approach used for the analysis is, multi-temporal monitoring and multi-level resource assessment (see Figure 1.2).