PHÂN VÙNG Ô NHIỄM NƯỚC TRONG CÔNG TRÌNH THỦY LỢI BẮC HƯNG HẢI

Abstract

Within researc scope of the project "Research on solutions to reduce water pollution in Bac Hung Hai irrigation system" implemented by the Institute for Water and Environment, the authors have surveyed 83 rivers and canals, consulted with irrigation operation units in combination with laboratory analysis to assess water pollution. The discussion of the results of water quality monitoring and synthesizing from 2005 to 2016 has evaluated the water pollution indicators in BHH irrigation work, including COD, BOD₅, NH₄⁺, NO₂^-, PO₄^3- and Coliform. After more than 10 years, COD content increased 8.6 times, NH₄⁺ content increased 2.48 times; PO₄^3- content increased 4.15 times and Coliform content increased 91.6 times. The heavy metals (As, Cr, Pb, Cd) although not exceeded Vietnamese Nation Standards (QCVN) but tended to increase over the years. The results of water pollution zoning of 83 rivers and canals based on water quality indexes (WQI), field descriptions of color, smell and extent of life of species in rivers and canals show that all the rivers have been contaminated on different levels, of which 19/83 rivers and canals are very severely polluted, 21/83 rivers and canals are severely polluted, 23/83 rivers and canals are moderately polluted and 20/83 rivers and canals are slightly polluted. At the same time, the analysis also shows the causes of water pollution and the impacts of water pollution on socio-economic development and people's life in the region. The research results are the scientific basis for the Water Resources Directorate to coordinate with localities in implementing measures to reduce water pollution in BHH irrigation work under the provisions of the Law on Irrigation and to serve the sustainable agricultural development.