The Changes of Ion Concentrations in the Stream Water during Rainfall Events by Forest Road Construction

概要

論文の詳細を見る
Hourly samples during rainfall events were collected at survey points A and B, on mountainous watersheds unaffected by a forest road, and C, affected by the forest road, in order to examine the effect of forest road construction on water quality in a stream. The constituents analyzed are cations Na^+, K^+, Mg^<2+>, Ca^<2+> and anions SO_4^<2->, NO_3^-, Cl^-, F^-. The relationship between the ion concentration and rainfall is affected more by the interval of an antecedent rain event than rainfall. Anions increase more than cations. This is remarkable at the survey point C, which is affected by the forest road. In the relationship between the ion concentration and discharge, Ca^<2+>, Mg^<2+>, Na^+, K^+, Cl^-, SO_4^<2-> and F^- concentrations decrease with an increase of discharge, however the NO_3^- concentration shows an opposite trend. At each of the survey points, most ion concentrations fall in the order of A>C>B but NO_3^- concentration shows the order of B>C>A. Cl^-, SO_4^<2-> and F^- concentrations, when affected by an interval of an antecedent rain event, appear higher at the survey point C than at the survey points A and B. The SO_4^<2-> concentration, mainly originating from the geological material, is regarded as an index expressing the effect of the forest road construction.
日本雨水資源化システム学会の論文