Another water quality parameter DO was also analyzed,
but the variation trend was not obvious. This was
probably because that DO content was not only influenced
by temperature, river runoff, but also by conditions
of water exchange and biological activities (Zhang
et al. 2007b); the organic matters transported from land
to river by precipitation were assimilated by aerobic organisms
using DO. Therefore, DO could not reflect the
relationship between water quantity and water quality
well. Prathumraana et al. (2008) also reported that DO
had weak correlations with river runoff.