Effect of land use on water quality: A case study in Trang Watershed

Abstract

            This research study existing condition and investigate the factors affecting the DO and BOD level in Trang watershed. Result found that most dominant land use type was agriculture (73%). During year 2003 to 2010, the area of urban, industry, water body and other have been increased indicated urban expansion. While, agricultural land has been decreased and possibly converted to urban or other land. Surprisingly, the area of forest land has been increased (1.66%) in a significant manner indicating the good reforestation activities in the watershed. Water quality of Trang watershed in year 2011 was within water quality standard class 3. Result found that the correlation between DO and BOD with changing in land use types can be evaluated by simple linear regression analysis and pearson correlation coefficient (r_xy). Factors affected on DO in Trang watershed are percentage of forest, agriculture, urban, industry, others land use, percentage development land use (PDLU), population density, temperature and electric conductivity respectively. Meanwhile, the BOD is affected by percentage of urban, industry, and EC respectively. The predicted model of DO and BOD could be accepted. It indicated that DO and BOD can be estimated by multiple linear regression analysis in Trang watershed. Therefore, higher percentages of developed land include industrial, urban, agricultural, cause water quality degradation. In the other hand, expansion of forest areas leads to improve water quality.

Keywords: DO and BOD, Land use, percentage of developed land use (PDLU)