A thesis submitted in partial fulfillment of the requirements for the degreeof Master ofEngineeringinWater Engineering and Management

Thesis (M. Eng.) - Asian Institute of Technology, 2013

With growing water demand and shortage of water from past few decades, monitoring and preserving quality of water has become a key point in management of water resources. The condition of water bodies is getting worst especially in region where, high land usesalterationand increasing population. In the present study 21 water quality parametersfrom 18 water quality monitoring station were analyzed to investigate the spatial and temporalvariability in particular with change in LULC,for 17 years (1994-2010) in the Mun River Basin, Thailand. Pearson correlation and multiple regression models were developed in SPSS to establish relationship between Land use and Water quality of the basin from1995 to 2010.Hydrologic model HSPF was chosen to simulate the stream flow and sediment transport for different land use scenario within the basin. The result shows the spatialheterogeneity of physio-chemical and biological characteristics of water in the Mun river basin. The change in land use heavily impacted the water qualityof upper and middle Munbasinby excess nutrient and solids with highest nutrient loadingrate whereas,lower Mun mainly affected by NH₃and heavy metals. Trend analysis of the parameters reveals that around 13 parameters are showing increasing trend, with pH, TS,Total-Coli, and most of the heavy metals increased the recommended drinking water limitsby WHO and PCD.Mostof the parameters displayhigh concentration during the dry season except metals like Manganese and Copper. Land use change analysis between 1995-2010 showsrapid increase in urban areas from 0.2 % to 7% andforest area from 14 % to 20%with decrease in land under agriculture from 82% to 67%with slight deforestation activities found between 2005 and 2010 in middle and lower Mun basin. Pearson correlation and multiple regression model indicated that BOD in the basin is closelyrelated with forest areawith R²>50%, p<0.05 followed by urban area. Nutrient mainly related to urban runoff and high fertilizer and pesticide use by agriculture and pasture land. While deforestation activity mainly affects the TS, SS and TDS concentration in middle Mun. Hydrologic model HSPF developed for the basin indicates increase in percent deviation of flow with observed flow for land use scenario developed for 2030.Where more deviation was especially during high flow years. Results clearly indicate that there is huge impact of LU change on WQ of Mun basin