The Study on Water Quality of the Return Flow in Lower Tap Salao Irrigation Project Hungspreug N. 1 Chooaksorn W. 2 and Sudcha P. 3 Department of Environmental Science, Faculty of Science and Technology, Thammasat University, Patumtanee, Thailand

Purpose Determine and compare water quality of the irrigation canal and drainage canal in Sakaekrang river basin, Thailand Department of Environmental Science, Thammasat University

Water degradation was clearly caused by agriculture sources (non-point sources). Introduction Department of Environmental Science, Thammasat University

Introduction (cont’) Irrigation canals Irrigated area Drainage canals Water Quality ?

In 1993, in USA 65 % of rivers suffered the impacts from non-point source pollution. (US Department of Pollution Control, 2002). In Thailand non-point sources pollution is the cause of severe water pollution. (Simachaya, 2000) Introduction (cont’) Department of Environmental Science, Thammasat University

Methodology Department of Environmental Science, Thammasat University

Study Area Southern Tap Salao in with part of Tab Salao irrigation project in the upper central part of Thailand. covering 14,000 ha. The water supply to this irrigation project came from the upstream Tab salao reservoir. Department of Environmental Science, Thammasat University

Southern Tap Salao irrigation project

Sampling Stations 45 water quality sampling stations. irrigation canal 22 stations drainage canal 23 stations collected samples during January 19 th -22 rd, 2007 Department of Environmental Science, Thammasat University

Water Quality Sampling Stations Drainage canal stations Irrigation canal stations

Drainage canal stations

Parameters. pH Conductivity (EC) Temperature (Temp) Turbidity (Tur) DO BOD NO 3 – -N NH 3 + -N PO P TS TDS SS Department of Environmental Science, Thammasat University

Results Department of Environmental Science, Thammasat University

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH ECµm/cm Temp.°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverag e NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH Conductivityµm/cm Temperature°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

pH

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH EC µm/cm Temperature°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

Conductivity µm/cm

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH Conductivityµm/cm Temp°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

Temperature °C

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH Conductivityµm/cm Temperature°C TurNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

Turbidity NTU

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH Conductivityµm/cm Temperature°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

Dissolved Oxygen (DO) mg/l

ParametersUnit Irrigation canalsDrainage canals RangeAverageRangeAverage pH Conductivityµm/cm Temperature°C TurbidityNTU DOmg/l BODmg/l Department of Environmental Science, Thammasat University

Biochemical Oxygen Demand (BOD) mg/l

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverage NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

NO 3 -N mg/l NH 3 -N

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverag e NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

Phosphate Phosphorus (PO P) mg/l

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverag e NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

Total Solid (TS)

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverage NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

Total Dissolved Solid (TDS)

ParametersUnitIrrigation canalsDrainage canals RangeAverageRangeAverag e NO - 3 mg/l NH + 3 mg/l PO 4 3- mg/l TSmg/l TDSmg/l SSmg/l Department of Environmental Science, Thammasat University

Suspended Solid (SS)

Conclusion

The water quality in the irrigation canals was better than in drainage canals. Department of Environmental Science, Thammasat University

The water quality in the irrigation canal was classified as class 3 (medium clean) (1) consumption after treatment process. (2) agriculture Conclusion (cont’) Department of Environmental Science, Thammasat University

The water quality in the drainage canal was classified as class 4 (fairly clean) (1) consumption after special treatment process (2) industry Conclusion (cont’) Department of Environmental Science, Thammasat University

The water quality in the irrigation canal was not significant different from that in the drainage canal. Conclusion (cont’) Department of Environmental Science, Thammasat University

Water drained from Irrigated area which mostly claimed as non point sources pollutant somehow the irrigation area can acts as constructed wetland which can improve some water quality parameters. Department of Environmental Science, Thammasat University Conclusion (cont’)

Recommendation

Water qualities monitoring programme should be continued at certain sampling stations over a longer period. Recommendation Department of Environmental Science, Thammasat University

Acknowledgement Staff of southern Tap Salao irrigation project, Royal Irrigation Department. Department of Environmental Science, Thammasat University

Thank you for your attention.