Little is known about the particular climate in Lam Pa Chi Basin (Manton et al., 2001) which due to its Southwestern mountain range is supposed to differ from the typical either Pacific or Himalayan influenced Southeast Asian climate. It is influenced by the southwest monsoon during the period from May to October and also the tropical cyclonic storms from the South China Sea at the end of the rainy season from September to October (Biltonen et al., 2003). According to the Köppen classification, the LPCRB belongs to the Aw group, with hot tropical climate (with average temperatures of all months above 18°C) including wet summers and relatively dry winters. 

Temperatures in the hottest month, April, reach an average temperature of 32°C while December is  the coldest with an average of 25°C.


According to the precipitation data available (3 stations) the annual precipitation ranges from 990 to 1180 mm. Almost 85% of the total precipitation falls during the wet season from May until November. During the rainy season heavy rain events occur causing one of the main environmental problems in the region: soil erosion. Figure 6 shows the inter-annual variation of monthly precipitation and discharge for the period 1967-2013 at the three stations. For instance at the station 47161 located in the center of the basin at 110 m.a.s.l., it can be seen that May, September and October are the months with the highest precipitation with average values of 160, 203 and 261 mm, respectively, while December until February are the driest months with average values under 15 mm.


For comparison, the average values for precipitation and discharge for Thailand are shown in the following figure:


This shows that the Lam Pa Chi river basin is exposed to a particular climate compared to the Thai mean, with two monsoon peaks, one in May and one in October. Mean rainfall is higher for entire Thailand during the whole year compared to Lam Pa Chi, only in October the rainy season by far exceeds the Thai mean. Consequently, discharge also differs with two peak flow seasons in May and October.


References and further reading:

Chanket, U., Mongkolsawat, C. (2009) An analysis of multi-temporal satellite data for land cover change and its impact on soil erosion over the upper namphong watershed, Northeast Thailand. 30th Asian Conference on Remote Sensing 2009, ACRS 2009, Beijing.

Henderson, G. S., Rouysungnern, S. (1985) Erosion and sedimentation in Thailand." Symposium on effects of forest land use on erosion and slope stability, 1984, Honolulu: 31-39.

Ishikawa, R. et al. (2006) Genetic erosion from modern varieties into traditional upland rice cultivars (Oryza sativa L.) in Northern Thailand, Genetic Resources and Crop Evolution 53(2): 245-252.

Jantawat, S. (1985) An overview of soil erosion and sedimentation in Thailand, Soil erosion and conservation: 10-14.

Krishna Bahadur, K. C. (2009) Mapping soil erosion susceptibility using remote sensing and GIS: A case of the Upper Nam Wa Watershed, Nan Province, Thailand, Environmental Geology 57(3): 695-705.

Lal, R. (2001) Soil degradation by erosion, Land Degradation and Development 12(6): 519-539.

LDD (2000) Soil Erosion in Thailand. Land Development Department, Ministry of Agriculture and cooperatives.

Meier, G., Zumbroich, T., Roehrig, J. (2013) Hydromorphological assessment as a tool for river basin management: The German field survey method, Journal of Natural Resources and Development 3: 14-26.

Morgan, R. P. C. (2009) Soil Erosion and Conservation, Wiley.

Morgan, R. P. C., Morgan, D. D. V., Finney, H. J. (1984) A predictive model for the assessment of soil erosion risk, Journal of Agricultural Engineering Research 30(C): 245-253.

Nontananandh , S., Changnoi, B. (2012) Internet GIS, based on USLE modeling, for assessment of soil erosion in Songkhram watershed, Northeastern of Thailand, Kasetsart Journal - Natural Science 46(2): 272-282.

Paiboonsak, S., Chanket, U., Mongkolsawat, C., Yommaraka, B., Wattanakit, N. (2005) Spatial modeling for soil erosion risk in upper Chi basin, Northeast Thailand, 26th Asian Conference on Remote Sensing, ACRS 2005 and 2nd Asian Space Conference, ASC, Ha Noi.

Paiboonvorachat, C., Oyana, T. J.  (2011) Land-cover changes and potential impacts on soil erosion in the nan watershed, Thailand, International Journal of Remote Sensing 32(21): 6587-6609.

Pensuk, A., Shrestha, R. P. (2010) GIS application for assessing the effects of land use change on surface runoff and soil erosion in phatthalung watershed, Southern Thailand, 31st Asian Conference on Remote Sensing 2010, ACRS 2010, Hanoi.

Plangoen, P., Babel, M. S., Clemente, R. S., Shrestha, S., Tripathi, N. K. (2013) Simulating the impact of future land use and climate change on soil erosion and deposition in the Mae Nam Nan sub-catchment, Thailand, Sustainability (Switzerland) 5(8): 3244-3274.

Renard, K. G., Foster, G. A., Weesies, G. A., McCool, D. K., Yoder, D. C. (1997) Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE), USDA Agriculture Handbook, Agricultural Research Service (USDA) 703: 404 pp.

Sang-Arun, J., Mihara, M., Horaguchi, Y., Yamaji, E. (2006) Soil erosion and participatory remediation strategy for bench terraces in northern Thailand, Catena 65(3): 258-264.

Shrestha, D. P., Suriyaprasit, M., Prachansri, S. (2014) Assessing soil erosion in inaccessible mountainous areas in the tropics: The use of land cover and topographic parameters in a case study in Thailand, Catena 121: 40-52.

Sriboonlue, V., Trelo-Ges, V., Pilawut, S., Khetkratok, N. (2004) Crop furrow erosion assessment in field crop plots in northeast Thailand, Transactions of the American Society of Agricultural Engineers 47(2): 419-425.

Sthiannopkao, S., Takizawa, S., Homewong, J., Wirojanagud, W. (2007) Soil erosion and its impacts on water treatment in the northeastern provinces of Thailand, Environment International 33(5): 706-711.

Turkelboom, F., Poesen, J., Ohler, I., Ongprasert, S. (1999) Reassessment of tillage erosion rates by manual tillage on steep slopes in northern Thailand, Soil and Tillage Research 51(3-4): 245-259.

Turkelboom, F., Poesen, J., Ohler, I., Van Keer, K., Ongprasert, S., Vlassak, K. (1997) Assessment of tillage erosion rates on steep slopes in northern Thailand Catena 29(1): 29-44.

Turkelboom, F., Poesen, J., Trébuil, G. (2008) The multiple land degradation effects caused by land-use intensification in tropical steeplands: A catchment study from northern Thailand, Catena 75(1): 102-116.

Weterings, R. (2011) A GIS-based assessment of threats to the natural environment on Koh Tao, Thailand, Kasetsart Journal - Natural Science 45(4): 743-755.

Wijitkosum, S. (2012) Impacts of land use changes on soil erosion in Pa Deng sub-district, adjacent area of Kaeng Krachan National Park, Thailand, Soil and Water Research 7(1): 10-17.

Wischmeier, W. H., Smith, D. D. (1978) Predicting Rainfall Erosion Losses - A Guide to Conservation Planning, 1st ed, Agriculture Handbook, ARS & USDA: 69 pp.

Ziegler, A. D., Giambelluca, T. W. (1997) Simulation of runoff and erosion on mountainous roads in northern Thailand: A first look, Proceedings of the 1997 5th Scientific Assembly of the International Association of Hydrological Sciences, IAHS, Wallingford, United Kingdom Rabat, Morocco, IAHS Press.

Ziegler, A. D., Giambelluca, T. W., Sutherland, R. A. (2001) Erosion prediction on unpaved mountain roads in northern Thailand: Validation of dynamic erodibility modelling using KINEROS2, Hydrological Processes 15(3): 337-358.

Ziegler, A. D., Giambelluca, T. W., Sutherland, R. A. (2001) Acceleration of Horton overland flow and erosion by footpaths in an upland agricultural watershed in northern Thailand, Geomorphology 41(4): 249-262.

FaLang translation system by Faboba