Based on Nemerow index method,27 typical cities all over China were chosen for the analysis of the present situation and spatio-temporal variation regulation of urban surface water. The results showed that TP,NH3-N,CODCr,BOD5 and CODMnwere major factors exceeding the standards and NH3-N was the most serious,and the water was mainly affected by nitrogen,phosphorus and organic pollution. Water quality in North China area was poorer. Water quality in Northwest,Northeast,East China,South China,Central China and Southwest area was better and their ratio of good quality was over 50%. Water quality in built up area was better than that of the unbuilt up area. Water quality of the state-controlled sections was relatively good. The pollution of typical cities surface water quality alleviated from 2012 to 2014,and the proportion of cities with low-quality water had decreased by 11%. In Northwest and Northeast,most cities did not show clear seasonal characteristics due to low population density,relatively slow economy development and relatively stable water quality. In the vast East China region,water quality did not show obvious quarterly fluctuations. In Central China and North China,water quality showedrelatively clear seasonal characteristics due to the influences of climate and rainfall.
Nemerow index method
water quality evaluation