1. 1820 m 3 km 1980 1997 JVC 2003 2004 2009 2. 1121 km 1914 km 2 600 m 1/5001/600 2 31
地域学研究 第 28 号 2015 図 1. ファーン川流域の概要と水質調査地点 Figure 1. Topography and distribution of check points for water quality in the Fang river basin. 32
2.1 : 250,000 Geological mapfederal Institute for Geosciences and Natural Resources, Germany, 1976. Figure 2. Geological map of the Fang river basin. Compiled from Federal Institute for Geosciences and Natural Resources, Germany, 1976. 33
28 2015 m 2000 m 107 2010 256 McQuistan 2004 Cl, NO 2, Ca, Br, NO 3, SO 4 TOA-DKK IA-200 IA-300HCO 3 Hardness CaMg2009 Hardness of watermg LCamg L 2.5 Mgmg L 4.1 128 2011 12 0 mm Tanaka et al. 20132012812 mm 2014 4. 3. 2009 2011 12 201281 12 EC ph TOA-DKK WM-22EPEC, ph COD Li, Na, NH 4, K, Mg, CaPO 4, F, 3 1 3a EC 57mS/m 40mS/m 2009 EC Ca 2 Mg 2 EC 34
Point # Name Lat. Lon. 1. Table 1. Results of water quality in the Fang river basin Distance km Date Temp. C ph EC COD TH ms/mmg/l mg/l Mae Fang Luang 19.597 99.184 12.4 2011/12/25 17.0 7.5 5.9 6.0 34.4 Huai Pong 19.616 99.513 17.2 2011/12/25 18.1 7.8 6.7 6.5 38.1 Ngaen Ngum 19.649 99.152 28.0 2011/12/25 19.3 7.9 13.9 8.0 81.1 Ai 19.681 99.150 32.4 2012/8/9 25.2 7.8 25.7 2.0 149.3 t1 Sai Khao Huai Sai 19.684 99.154 33.3 2012/8/9 25.1 7.8 17.8 13.0 108.0 Ban Ai Dam 19.687 99.153 33.4 2012/8/9 25.8 7.8 26.9 5.0 156.2 Si Dong Yen 19.706 99.147 35.9 2012/8/9 26.1 8.2 36.5 7.0 238.4 Huai Phai 19.734 99.143 39.6 2011/12/27 19.7 8.3 40.1 6.5 249.5 t2 Tha Nam Mae Thalop 19.736 99.149 40.8 2012/8/9 26.3 7.9 23.3 13.0 San Sai 19.909 99.220 76.6 2011/12/27 19.5 8.2 29.2 8.5 168.8 t3 Pong Nam Ron Nam Mae Chai 19.946 99.165 77.9 2012/8/9 25.5 8.1 5.5 15.0 26.0 Tha Mai Liam 20.021 99.354 112.5 2012/8/9 27.4 7.9 15.1 13.0 78.1 Point # Li Na NH 4 K Mg 2 Ca 2 PO 4 3 F Cl NO 2 unit: mg/l 0.001 1.88 0.00 1.50 3.07 8.73 0.00 0.00 0.69 0.00 0.00 0.00 3.96 26 0.002 2.52 0.00 1.45 3.39 9.69 0.00 0.00 0.00 0.00 0.00 0.00 3.09 34 0.003 2.48 0.00 1.43 5.40 23.60 0.00 0.00 0.55 0.00 0.00 0.00 4.38 68 0.000 2.54 0.00 1.99 6.85 48.50 0.00 0.00 2.58 0.00 0.00 2.73 5.70 128 t1 0.000 2.85 0.04 2.49 5.98 33.40 0.00 0.00 1.69 0.00 0.00 0.94 4.46 96 0.005 2.44 0.00 1.81 7.24 50.60 0.00 0.00 2.64 0.00 0.00 2.73 5.63 136 0.010 3.42 0.00 2.32 11.80 76.00 0.00 0.00 3.98 0.00 0.00 4.42 7.80 188 0.014 1.97 0.00 1.54 13.10 78.30 0.00 0.00 2.91 0.00 0.00 5.43 4.07 220 t2 0.014 3.56 0.00 2.99 8.79 53.10 0.00 0.00 4.23 0.00 0.00 3.93 5.16 144 t3 0.004 3.13 0.00 1.94 1.53 8.56 0.00 0.30 0.77 0.00 0.00 0.75 2.34 28 0.000 4.34 0.00 4.31 4.59 23.70 0.00 0.01 4.66 0.00 0.00 2.83 3.35 68 Br NO 3 SO 4 2 HCO 3 Point # Li Na NH 4 K Mg 2 Ca 2 PO 4 3 F Cl NO 2 unit: meq/l 0.00 0.08 0.00 0.04 0.25 0.44 0.00 0.00 0.02 0.00 0.00 0.00 0.08 0.52 0.00 0.11 0.00 0.04 0.28 0.48 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.68 0.00 0.11 0.00 0.04 0.44 1.18 0.00 0.00 0.02 0.00 0.00 0.00 0.09 1.36 0.00 0.11 0.00 0.05 0.56 2.42 0.00 0.00 0.07 0.00 0.00 0.04 0.12 2.56 t1 0.00 0.12 0.00 0.06 0.49 1.67 0.00 0.00 0.05 0.00 0.00 0.02 0.09 1.92 0.00 0.11 0.00 0.05 0.60 2.52 0.00 0.00 0.07 0.00 0.00 0.04 0.12 2.72 0.00 0.15 0.00 0.06 0.97 3.79 0.00 0.00 0.11 0.00 0.00 0.07 0.16 3.76 0.00 0.09 0.00 0.04 1.08 3.91 0.00 0.00 0.08 0.00 0.00 0.09 0.08 4.40 t2 0.00 0.15 0.00 0.08 0.72 2.65 0.00 0.00 0.12 0.00 0.00 0.06 0.11 2.88 t3 0.00 0.14 0.00 0.05 0.13 0.43 0.00 0.02 0.02 0.00 0.00 0.01 0.05 0.56 0.00 0.19 0.00 0.11 0.38 1.18 0.00 0.00 0.13 0.00 0.00 0.05 0.07 1.36 Br NO 3 SO 4 2 HCO 3 EC Ca 2 Mg 2 35 Ca 2 Mg 2 121 3a limestone area
28 2015 3. Figure 3.Change of water quality along main stream of the Fang river. EC EC 3at1, t2, t3 EC 36 2012 8 3 4
5. 4.Ai Figure 4. Agricultural Dam at Ban Ai (point, main stream of the Fang river. 20 km Ca 2 Mg 2 EC 33 km 40 km 40 km EC Ca 2 Mg 2 3 b 37 3bCa 2 Mg 2 2011 Na Cl Na/Cl 5 3,, 2t1, t2na/cl1 : 1 Na 5Na Cl NaCl Na Na/Cl Na Cl NO 3 6.
28 2015 5. Figure 5.Relationship between sodium and chloride concentrations in the Fang river basin. 20112012 EC 20 km EC EC 33 km EC 38 EC Na/Cl 5 NaCl EC
NGO Link 20082013 JVC 2003 3NGO 29 ppjvc 2004 2 60 pp 2011 43: 29 38 2009 176 pp 2014 Braun, E. V., and Hahn, L. eds. 1976. Geological Map of Northern Thailand 1 : 250000, Sheet 2 (Chiang Rai), Federal Institute for Geosciences and Natural Resources, Germany. McQuistan, C. 2004. RRA Report on Mae Gok Watershed in Chiang Mai and Chiang Rai Provinces. 33 pp, Regional Environmental Technical Assistance 5771, Poverty Reduction & Environmental Management in Remote Greater Mekong Subregion Watersheds Project (Phase I). http:// www.mekonginfo.org/assets/midocs/0003143- inland-waters-rra-report-on-mae-gok-watershedin-chiang-mai-and-chiang-rai-provinces.pdf (last accessed 10 Jan 2015) Tanaka, Y., YANAGIBA, S., and Satoh, T. 2013. Geographical data book of the Fang River Basin 2011. 13 pp, Department of Geography and Institute for Applied Geography, Komazawa University. 39
28 2015 Surface Water Quality and its Formation Processes in the Fang River Basin, Northern Thailand Yasushi TANAKA*, Masahiro TAKAGI*, Tetsuo SATOH*, Survey Participants of Northern Thai Seminar, Komazawa University** We measured the surface water quality in the basin of the Fang River, which is one of the upper tributaries of the Mekong River in northern Thailand, and discussed its formation processes from the viewpoints of geology, current landuse and human impacts. The water quality along the main stream of the Fang River changes as follows: 1) At the farthest upstream segment (ca. 0 20 km from the headwaters area near Doi Wiang Pha), the river is a clear stream containing few dissolved ions. 2) In the segment from ca. 20 km to agricultural Dam point (ca. 33 km), hard water which includes rich calcium and magnesium ions flows into the main stream of the Fang River, bringing about the effect of limestone. Paleozoic limestone is widely overlaid on the left (west) side of the upstream of Fang River, and it is found that this is one of the keys to understanding the formation process of water quality in the watershed. The hard water has an effect on Electrical Conductivity (EC) as the value of EC suddenly grows in this segment. But this does not mean that the water is polluted. 3) At the agricultural Dam point, most of the main stream water is diverted, and therefore it resets the water quality of the main stream except the rainy season. 4) Between the downstream of the Dam point and Huai Phai point (ca. 40 km), almost all main stream water is formed by the runoff water from the neighboring limestone areas. As a result, EC and Total Hardness (TH) indicate the maximum value in this segment. 5) At the downstream from the ca. 40 km point, the main stream water is diluted by tributary flows that do not run through limestone areas. Therefore EC and TH values decrease as far as Tha Mai Liam point (ca. 100 km). Next, we examined human impacts on the water quality by use of relationship between sodium and chlorine ion concentrations. We detected a weak human signal between Ai point (ca. 32 km) and Tha Mai Liam point (ca. 100 km). But since its absolute values are not so large compared with ordinary river water quality of urban/suburban area, we estimated it will not have a bad influence on human life. * Department of Geography, Komazawa University ** Northern Thai Seminar, Komazawa University (Satsuki YANAGIBA, Shihori TOYOKURA, Mifuka ISHIKAWA, Tomoko KIYOTA, Masahiro ISEKI) 40