Advertisement

Evaluation of Evapotranspiration in Forested Areas in the Mekong Basin Using GIS Data Analysis

  • Shinji Sawano
  • Norifumi Hotta
  • Hikaru Komatsu
  • Masakazu Suzuki
  • Tomoko Yayama

Abstract

We assessed evapotranspiration in the Mekong River basin with a focus on the distribution of forested areas using geographic information system (GIS) datasets. We developed a new model to estimate evapotranspiration, a major component of the forest water budget. The model calculates transpiration (including forest floor evaporation) and interception loss separately. Transpiration was calculated based on the Priestley-Taylor equation. Interception loss assumed a constant interception ratio. After clarifying distributions of climatic conditions and forested area in the basin, we calculated the evapotranspiration rate distribution. We then identified significant factors to consider in accurate estimation of evapotranspiration by comparing evapotranspiration rates based on the model and those based on the original form of the Priestley-Taylor equation. Consequently, we concluded that the contribution of evergreen and deciduous broadleaf forests in the southern part of the basin is one of the dominant components of evapotranspiration from the whole basin, because those forests are distributed in an area with high evaporative potential and the forests cover a large area. Furthermore, it is essential to evaluate the transpiration control of evergreen broadleaf forests in the lower part of the basin because of decreases in soil moisture during the dry season.

Keywords

Forested Area Mekong Delta Deciduous Broadleaf Forest Evergreen Broadleaf Forest Mekong River Commission 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Hansen MC, Defries RS, Townsend JRG, Sohlberg R (2000) Global land cover classification at 1 km spatial resolution using a classification tree approach. Int J Remote Sens 21:1331–1364CrossRefGoogle Scholar
  2. Kamoto M (2004) Challenges of the Mekong River Commission (in Japanese with English abstract). J Jpn Soc Hydrol Water Resour 17:181–199CrossRefGoogle Scholar
  3. Kazama S, Sawamoto M, Nawarathana NB (2001) Basic study on the evaluation of water resources in the Mekong River Basin (in Japanese with English abstract). Ann J Hydraulic Eng JSCE 45:19–24Google Scholar
  4. Kira T (1971) Seitaigaku kara mita shizen (in Japanese). Kawadeshobo, TokyoGoogle Scholar
  5. Kite G (2001) Modeling the Mekong: hydrological simulation for environmental impact studies. J Hydrol 253:1–13CrossRefGoogle Scholar
  6. Komatsu H (2005) Forest categorization according to dry-canopy evaporation rates in the growing season: comparison of the Priestley-Taylor coefficient values from various observation sites. Hydrol Process 19:3873–3896CrossRefGoogle Scholar
  7. Komatsu H, Hashimoto S, Kume T, Yoshifuji N, Hotta N, Suzuki M (2007) Seasonal trends in the solar radiation/net radiation ratio above a Cryptomeria japonica plantation forest. Bulletin of Tokyo University forest, acceptedGoogle Scholar
  8. Kondo J (1993) A new bucket model for predicting water content in the surface soil layer (in Japanese with English abstract). J Jpn Soc Hydrol Water Resour 6:344–349Google Scholar
  9. Kondo J (1994) Sekai no suimonkikou. In: Kondo J (ed) Mizukankyo no kishogaku. Asakurashoten, Tokyo, pp 308–322Google Scholar
  10. Kuraji K, Tanaka N (2003) Rainfall interception studies in the tropical rainforest J Jpn For Soc 185:18–28 (in Japanese with English abstract)Google Scholar
  11. Manabe S (1969) Climate and the ocean. 1: The atmospheric circulation and the hydrology of the Earth’s surface. Mon Weather Rev 97:739–774CrossRefGoogle Scholar
  12. Matsumoto J (1997) Seasonal transition of summer rainy season over Indochina and adjacent monsoon region. Adv Atmos Sci 14:231–245CrossRefGoogle Scholar
  13. Meeson BW, Corprew FE, McManus JMP, Myers DM, Closs JW, Sun KJ, Sunday DJ, Sellers PJ (1995) ISLSCP Initiative 1.Global data sets for land-atmosphere models, 1987–1988. Published on CD-ROM by NASA (USA_NASA_GDAAAC_ISLSCP_001.-USA_NASA_GDAAC_ISLSCP_005Google Scholar
  14. Mekong River Commission (2003) State of the basin report. Mekong River Commission, Phnom Penh. pp 185–204Google Scholar
  15. Nemani RR, Pierce L, Running SW, Goeard S (1993) Developing satellite-derived estimates of surface moisture status. J Appl Meteorol 32:548–557CrossRefGoogle Scholar
  16. Nishida K, Nemani RR, Glassy JM, Running SW (2003) Development of an evapotranspiration index from Aqua/MODIS for monitoring surface moisture status. IEEE Trans Geosci Remote Sensing 41:493–501CrossRefGoogle Scholar
  17. Otsuki K, Miura T, Takase K (1989) Evapotranspiration, vol 7. Evapotranspiration in largescale area (in Japanese). J JSIDRE 57:133–139Google Scholar
  18. Priestley CHB, Taylor RJ (1972) On the assessment of surface heat flux and evaporation using large-scale parameters. Mon Weather Rev 100:81–92CrossRefGoogle Scholar
  19. Sawano S (2003) Simple model for evaluating the evapotranspiration of a forested area in Japan (in Japanese). MS thesis. University of Tokyo, Tokyo, JapanGoogle Scholar
  20. Takase K, Sato K (1989) Evapotranspiration, vol 6. Evapotranspiration in crop land (in Japanese). J JSIDRE 57:75–80Google Scholar
  21. Tanaka K, Takizawa H, Tanaka N, Kosaka I, Yoshifuji N, Tantasirin C, Piman S, Suzuki M, Tangtham N (2003) Transpiration peak over a hill evergreen forest in northern Thailand in the late dry season: assessing the seasonal changes in evapotranspiration using a multilayer model. J Geophys Res 108:4533CrossRefGoogle Scholar
  22. Yatagai A, Yamazaki N, Horikama H, Takahashi K, Ueda H, Aonashi K, Sumi K, Takeuchi Y, Tada H (2000) About GAME reanalysis data (in Japanese). J Jpn Soc Hydrol Water Resour 13:486–495Google Scholar

Copyright information

© Springer 2007

Authors and Affiliations

  • Shinji Sawano
    • 1
  • Norifumi Hotta
    • 1
  • Hikaru Komatsu
    • 2
  • Masakazu Suzuki
    • 1
  • Tomoko Yayama
    • 1
  1. 1.Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
  2. 2.Institute of Industrial SciencesThe University of TokyoTokyoJapan

Personalised recommendations