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Optimal Allocation of Waste Loads in a River with Probabilistic Tributary Flow Under Transverse Mixing
Author(s) -
Li Shiyu,
Morioka Tohru
Publication year - 1999
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143099x121472
Subject(s) - tributary , environmental science , wastewater , hydrology (agriculture) , drainage basin , mixing (physics) , water quality , flow (mathematics) , environmental engineering , pollutant , hydraulics , volumetric flow rate , geology , geotechnical engineering , mathematics , engineering , geography , ecology , mechanics , physics , cartography , geometry , quantum mechanics , aerospace engineering , biology
A model is proposed for the optimal allocation of waste loads in a river basin, taking into account transverse mixing resulting from the confluence of tributaries with different pollutant levels and the variation of river flow rates. The model is stated as the minimization of cost of wastewater treatment in the whole river basin, subject to the satisfaction of environmental standards imposed for the river quality at water intakes along the river. The flow rate of the river system is regarded as a random variable in the model and constraints on water quality levels are expressed in a probabilistic form. The model is applied to a river with three tributaries joining at one point. The frequency of flow rate of the river system is approximately represented by that of flow rate groups obtained by using statistical methods.
Results of the model application show that the priority of wastewater treatment shifts from one tributary subbasin to another when environmental standards are changed, reflecting the effect of transverse mixing in the mainstream. Water quality violations caused by flow rate groups are discussed in the study.