Dynamics of Nonpoint Source Pollutant Loadings from Agricultural Watershed : A Case Study in Paddy-farming Area with 122 Drainage Water Outfalls Exactly Identifiable

概要

論文の詳細を見る
Paddy farming is the cause of water pollution in many parts of the Asian monsoon district. As a primary study for strategically managing river water quality on a watershed scale, the dynamics of nonpoint source pollutant loadings from paddy farming area are examined for a selected agricultural watershed where a river runs through and rice paddies take greater part of the farmland. A total of 122 outfalls at which drainage (irrigation runoff) waters enter the river are exactly identifiable along the whole course of the river. Results of the detailed surveys of drainage waters, conducted at typical stages in an indigenous calendar of paddy farming practice (CPFP) in an irrigation season as well as at a few stages in the off-season, are analyzed. Major findings are as follows. (1) Any of the COD_<Mn>, NO_3-N, T-N and T-P loadings totalized over all the outfalls is maximized in puddling and transplanting with basal fertilizer application. (2) The concentrations of NO_3-N and T-N, averaged over all the outfalls, are rather low during the irrigation period of mid April to early September. Nevertheless the loading amounts of them remain high during the same period, relatively closely correlating with the amount of outfall discharge. (3) Topdressing the paddies in the booting stage of rice causes a distinguishable extra load of NO_3-N. (4) The dynamics of the COD_<Mn> and T-P loadings are totally different from those of the NO_3-N and T-N loadings, taking straightforward declines from their maximums or being significantly restricted by their concentrations rather than by outfall discharges.

Dynamics of Nonpoint Source Pollutant Loadings from Agricultural Watershed : A Case Study in Paddy-farming Area with 122 Drainage Water Outfalls Exactly Identifiable

スポンサーリンク

概要

著者

関連論文

スポンサーリンク