5. Conclusion

• The LWCI enables us to examine the relation between the satellite data and the ground truth data owing to its characteristic of physical quantites.
• The TM channels used for LWCI calculation are channel 4 and 5, which are not susceptible to influences from the atmospheric noise. Therefore, LWCI is suitable for the comparison of seasonal fluctuation of vegetation condition.
• Regional water condition map can be create using multi-temporal LWCI images. This map may supply the approach to understand water environmental changes in the tropical monsoon forest such as defoliation, evapotranspiration so on that correspond to its phonological dynamics.
• Integrating various kinds of GIS data such as DEM and satellite LWCI image, it is possible to conduct environmental gradient analysis of a target area to get useful information about the landuse (e.g. vegetation type, planted species, etc.).

Acknowledgements
This work was performed on the subject of environmental change analysis with forest monitoring information by the cooperative system for supporting priority research of Japan Department and National Research Council of Thailand for collaboration and the data providing.

References

• Boyd, D.S.,Foody, G,M.,Curran,P.J.,Lucas,R.M.,and Honzak, M., 1996.An assessment of radiance in Landsat TM middle and thermal infrared wavebands for the detection of tropical forest regeneration. Int.J.Remote Sensing,17,pp.249-261.
• Raymond Hunt, Jr.E.,Barrett,N.R.Park,S.N.,1987.Measurement of Leaf Relative Water Content by Infrared Reflectance. Remote Sensing of Environment,22,pp.429-435.
• Inoure, Y.,1993.Non-destructive Estimation of Water Status of Intact Crop Leaves Based on Spectral Reflectance measurements, Jpn.j.Crop Sci.,62(3),pp.462-469.
• Sawada H.,H.Saito, Y. Hirata and G.Takao., 1995. Characteristics of seasonal changed of forest observed by satellites, Proceedings of the international workshop on "The Changes of Tropical Forest Ecosystems by EL Nino and Others". Pp-241-246.

Fig.1 The spectral reflectance curve of the leaves exposed to the water stress and non stress.
---- RWC (Relative water content)=99.2%, -Rwc=12.2%
(Inoue,et al, 1993, material: peanut)



Fig.2 Seasonal Change Images of LWCI in Kanchana Buri



Fig.3 Comparison of LWCI with Meteorological Data in Seasonal Change



Legend: LWCI Change Pattern Class(e.g. H.M.L. means high LWCI value in the early, middle value in the middle, low value in the last stage)



Fig.5 The Study Area is geographically divided into 3 Watersheds



Fig.6 Correlation between Water Availability Classes and Elevation at the 3 Watersheds

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