Relationship between river water quality and land

Authors: Md Mezbaul Bahar Hiroo Ohmori Masumi Yamamuro

Publish Date: 2008/02/28

Volume: 9, Issue: 1, Pages: 19-26

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Abstract

In this study the relationship between water quality as represented by major inorganic ion concentrations and land use characteristics is examined for a small river basin which runs through the urbanizing area of central Japan Water samples were taken from 24 sites at base flow and analyzed and the proportions of the various land uses associated with the respective drainage basins were calculated using a digital landuse map scale 125000 The electrical conductivity EC of the water ranged from 845 to 600 μS cm−1 Ca2+ and Na+ were the major cations accounting for 77 of all cations Among the anions HCO3 − was dominant 56 followed by Cl− 24 SO4 2− 13 and NO3 − 7 Applying principal component analysis to land use in the drainage basin yielded three principal components The first principal component expressed the degree of occupation by residential areas the second indicated the degree of urban developing area ie fastdeveloping and industrial areas and the third showed the degree of coverage with farmland and green space The residential area showed significant positive correlations with K+ Mg2+ Ca2+ NO3 − HCO3 − EC and TMI total major ions Urban developing area showed significant positive correlations with Ca2+ Cl− HCO3 − EC and TMI as well as weak negative correlations with NO3 − and SO4 2− Industrial area showed weak positive correlations with Na+ and Cl− and a moderate negative correlation with NO3 − Farmland showed significant positive correlations with NO3 − and SO4 2− these ions are present due to fertilizers and the biological activity of plants Forest area is inversely related to almost all ions indicating the need for this form of land use in order to maintain river water qualityThe authors would like to thank the Environment Section of Kashiwa City Hall Chiba Prefecture Japan for providing the drainage area map of Ohori River and its tributaries The authors are grateful to Dr Yasushi Agata for his help during the field surveys and GIS analysis Financial support from ADBJSP during this study is gratefully acknowledged

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