Relationship between land use and water quality in a small watershed in South Korea

摘要

Recent research and monitoring undertaken by various institutions have emphasizednmeasurements of river-water quality. Based on the results, government agencies have setnguidelines to improve river-water quality management. However, the relationship betweennwater quality and land use/land cover (LULC) has not been examined closely in South Koreanto date. This study investigated this relationship in the Imgok River watershed. For this study,nthe relationship between water quality parameters, e.g. metallic ions, biological oxygen demandnand chemical oxygen demand (BOD and COD), NH3, NO3 and PO4 levels and land-use typesn(abandoned mine land, forest/grassland, agricultural, livestock and residential areas) wasnexamined by correlation analysis with significant level ( p , 0.05) and principal componentnanalysis (PCA). Applying PCA to water quality parameters according to land-use coverage,nthe principal component impacting river water quality were found to be the pH, metallic ions,nBOD, PO4, COD and total suspended solids (TSS) for abandoned mine land (AML) coverage;nBOD, NO3 and PO4 for forest/grassland areas; TSS, NO3, and PO4 for agricultural land; BOD,nCOD, NH3 and NO3 for livestock coverage; and BOD, COD, NH3 and PO4 for residential areas. Fornthe AML, the pH exhibited a significant negative correlation with other water quality parametersnat the significant level ( p , 0.05). Grassland showed significant positive correlations of BOD withnvalues of 0.837 NO3 and 0.514 PO4. In agricultural land, TSS had a significant negative correlationnwith value of 20.772 PO4. For livestock coverage, BOD had significant positive correlations withnvalues of 0.865 COD, 0.629 NH3, 0.709 NO3 and 0.472 TSS. In residential areas, COD wasnsignificantly positively correlated with values of 0.988 BOD and 0.856 PO4, and TSS was highlynpositively correlated with value of 0.810 NO3 but highly negatively correlated with value ofn20.702 PO4. Based on the above, LULC is a significant factor to influence on river water qualitynand this relationship should be based on the management plan for river water quality control.nFuture work will be conducted to take more samples in the entire river and season, to run waternquality model and to choose a new method for better analysis and more accurate relationshipnbetween land-use and water quality.