Statistical analyses on the effects of air temperature fluctuations on river water qualities

✍ Scribed by Noriatsu Ozaki; Takehiko Fukushima; Hideo Harasawa; Toshiharu Kojiri; Katsunori Kawashima; Miyuki Ono

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 196 KB
• Volume: 17
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.1437

✦ Synopsis

Abstract

In order to gain an insight into the effects of air temperature on river water quality, data were statistically analysed using meteorological and river water quality data. Two types of data set were used for river water temperature. One type involved five sampling points within different rivers where water temperature data were obtained daily, and the other involved 82 sampling points located within 27 rivers where water temperature and other water quality data were obtained monthly. Influential factors for different time scales were investigated. From the analyses, the gradient of water temperature to air temperature considered on a daily scale was 0·1–0·5 °C °C^−1^ and was influenced by the hydrological scale of the river basin. The gradient observed using an annual scale was 0·5–1·5 °C °C^−1^ and was supposed to be influenced by solar radiation. Under the condition that solar radiation is constant, the gradient on an annual scale was predicted to be less than unity (0·5–0·85 °C °C^−1^). As for the other indices, from the analysis on an annual scale, an increase in air temperature resulted in an increase in biological oxygen demand and suspended solids, and a decrease in dissolved oxygen in almost all rivers. Based on the results, it was suggested that global warming has a deteriorating effect on river water quality. Copyright © 2003 John Wiley & Sons, Ltd.