scholarly journals Deterministic and Stochastic Principles to Convert Discrete Water Quality Data into Continuous Time Series

Author(s):  
Danieli Mara Ferreira ◽  
Marcelo Coelho ◽  
Cristovão Vicente Scapulatempo Fernandes ◽  
Eloy Kaviski ◽  
Daniel Henrique Marco Detzel

Abstract Limited water quality data is often responsible for incorrect model description and misleading interpretation in water resources planning and management scenarios. This study compares two hybrid strategies to convert discrete concentration data into continuous daily values for one year in different river sections. Model A is based on an autoregressive process, accounting for serial correlation, water quality historical characteristics (mean and standard deviation) and random variability; the second approach (model B) is a regression model, based on the relationship between monitoring flow and concentrations, plus an error term. The generated series (here referred to as synthetic series) are propagated in time and space by a full deterministic model (SihQual), that solves the Saint-Venant and advection-dispersion-reaction equations. Results reveal that both approaches are appropriate to reproduce the variability of biochemical oxygen demand and organic nitrogen concentrations, leading to the conclusion that the combination of deterministic/empirical and stochastic components are compatible. A second outcome arises from the comparison of results in different time scales, supporting the need for further assessment of statistical characteristics of water quality data - which relies on monitoring plans. Nonetheless, the proposed methods are suitable to estimate multiple scenarios of interest in water resources planning and management.

1985 ◽  
Vol 17 (6-7) ◽  
pp. 879-890 ◽  
Author(s):  
Edwin E. Herricks

With increased emphasis on environmental quality objectives in water resources planning and management, past practices of simply considering water quality as the only environmental quality objective are inappropriate. Expanded environmental quality objectives include maintenance of high quality aquatic habitat. Water resource systems must provide both physical and chemical conditions appropriate for the propagation and maintenance of healthy diverse aquatic communities. Managing water resources to provide high quality habitat involves planning to meet both water quality and water quantity objectives. Existing technology based water quality controls and stream based water quality criteria can now be supplemented by aquatic habitat management. An approach to aquatic habitat management is illustrated by use of the Incremental Methodology developed by the U. S. Fish and Wildlife Service. The Incremental Methodology uses measures of aquatic habitat to assess instream flows required for by aquatic life. Thus the range of environmental quality objectives in resources planning and management is expanded by application of these methods to include aquatic habitat as well as water quality management. Methods used to determine instream flow needs for rivers in Illinois are reviewed, and the use of this information in developing regulations limiting water extraction for off stream use are described. Aquatic habitat based management is shown to provide workable methods to meet expanded environmental quality objectives in water resources planning and management.


1984 ◽  
Vol 16 (5-7) ◽  
pp. 33-39
Author(s):  
S J Hugman

Mozambique lies on the south-east coast of Africa. Its Independence, in 1975, was particularly difficult and severely disrupted the economy. All its major rivers rise in neighbouring countries and several, in particular those from South Africa and Swaziland, are already heavily used before crossing the border. Since 1977 the National Water Directorate has been responsible for management and development of water resources. The Directorate includes a hydrology department which maintains field-teams throughout the country. Virtually no water quality data are available from before 1972, when irregular sample collection began. Since Independence, sampling has continued but the Directorate has redefined the objectives of the programme to obtain maximum benefit from very limited resources. These objectives were chosen for economic, hydrological and political reasons. The long-term objectives are to provide the data required for agricultural and industrial development projects, to manage and maintain the quality of Mozambique's water resources, and to meet international obligations. In practice, the capacity of the hydrological service is insufficient to meet these objectives. The targets for the existing programme were therefore chosen to satisfy the most important objectives and to be feasible with present resources. The routine programme is being completely operated by technicians who have no more than nine years schooling.


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