Preface

Areas of restricted water supply are increasing in most developing countries due to rapid increases in populations and remarkable industrial development. Especially in Asian countries, rapid development, and concomitant increases in population and poverty, have led to land use changes, including high levels of illegal logging and the conversion of forest areas into agricultural land for food security. This and other large-scale environmental changes have exacerbated problems such as flooding and droughts and increased the demand for water, even as the water-holding capacity of the terrain has declined as forests have been logged. In addition, it is predicted that the spatiotemporal distribution of precipitation will change in many areas, due to changes in the global climate, which could potentially increase damage caused by floods or drought. Japan, located in the Asian monsoon area, could have a strong influence on the possible solutions to such regional problems. Harmonization between conservation and the need for local inhabitants to utilize water and timber resources is an important issue that should be addressed cooperatively between Japan and other countries facing these problems.

Individual observational studies have been performed in various areas of the southeastern Asian tropical seasonal forest, including the Indochina peninsula. However, there are no data on the water cycle in forested areas, because observations were seldom conducted in Cambodia, which is located approximately in the central part of southern Indochina, before the early 2000s. Cambodia has developed rapidly recently, but remains a very valuable area with much standing forest on the plains of the lowlands. It is very likely that these are remnants of forests that were formerly distributed throughout the Indochina peninsula. In other areas that have already been developed, these forest remnants are often found in high, mountainous areas where land-use is difficult.

There are various types of forest in the Mekong River basin, from alpine to tropical seasonal forests. However, no previous study has examined the differences in the water cycles of different types (evergreen and deciduous) of tropical seasonal forest, although a recent study reported that differences in the seasonal variation in energy and water cycles between evergreen and deciduous forests are wider in tropical than in temperate areas. Therefore, to understand water cycle variation and to estimate the water resources in the Mekong River basin, in particular in lowland Cambodia, it is necessary to elucidate these phenomena based on long-term observational data. To this end, it is necessary to construct an observation system for detailed water cycle studies in evergreen and deciduous forest basins, and to connect this system with remote sensing and other local observation systems to construct an observation network for the whole tropical seasonal forest area.

The Forestry and Forest Products Research Institute and Laboratory of Forest Hydrology and Erosion Control Engineering, Graduate School of Agricultural and Life Sciences, University of Tokyo has built an infrastructure of comprehensive observation sites for evergreen, deciduous, and artificial forests to observe the variation in forest water cycles in the Mekong River basin of Cambodia and the Indochina peninsula.

Data from this system have been generated since 2003, and this website has published some of the findings. Furthermore, the website links to a site of the Sawada and Takeuchi Laboratory, Institute of Industrial Science, University of Tokyo, that contains the warning system to find the development activities and land cover changes in these forested areas. This aspect of the system is the result of the latest project by the Sawada and Takeuchi Laboratory, and applicants are able to use the system. Remote-sensing datasets resulting from the allied project that started in 2002 are also accessible. Although there are plans to accumulate more data from future investigations and observations, this webpage currently consists mainly of results from the latest project, which finished in 2011, with some additional results from earlier projects. We believe that this webpage will contribute to studies of variation in water cycles, forest conversation and management, and environmental preservation in the relevant regions.

The research projects for the products and data sets

"Establishment of the Integrated Forest Ecosystem Observation Sites and Network in the Lower Mekong" funded by the Ministry of Environment of Japan (2008-2011).
"Model development, simulation and assessment of the effects of human activities and natural change on the water resources in Mekong River basin (RR2002; 2002-2006)" funded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
"Assessment of the impact of Global-Scale change in water cycles on food production and alternative policy scenarios (2003-2007)" funded by Agriculture, Forestry and Fisheries Research Council Secretariat, Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan.

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