A parsimonious dynamic model for river water quality assessment

Abstract

Water quality modelling is of crucial importance for the assessment of physical, chemical, and biological changes in water bodies. Mathematical approaches to water modelling have become more prevalent over recent years. Different model types ranging from detailed physical models to simplified conceptual models are available. Actually, a possible middle ground between detailed and simplified models may be parsimonious models that represent the simplest approach that fits the application. The appropriate modelling approach depends on the research goal as well as on data available for correct model application. When there is inadequate data, it is mandatory to focus on a simple river water quality model rather than detailed ones. The study presents a parsimonious river water quality model to evaluate the propagation of pollutants in natural rivers. The model is made up of two sub-models: a quantity one and a quality one. The model employs a river schematisation that considers different stretches according to the geometric characteristics and to the gradient of the river bed. Each stretch is represented with a conceptual model of a series of linear channels and reservoirs. The channels determine the delay in the pollution wave and the reservoirs cause its dispersion. To assess the river water quality, the model employs four state variables: DO, BOD, NH(4), and NO. The model was applied to the Savena River (Italy), which is the focus of a European-financed project in which quantity and quality data were gathered. A sensitivity analysis of the model output to the model input or parameters was done based on the Generalised Likelihood Uncertainty Estimation methodology. The results demonstrate the suitability of such a model as a tool for river water quality management.

A new unconditionally stable and consistent quasi‐analytical in‐stream water quality solution scheme for CSTR‐based water quality simulators

“…The use of analytical solutions for simple water quality problems is common [ Ciaponi et al ., ; Loucks et al ., ; Socolofsky and Jirka , ; Wallis , ; Mannina and Viviani , ; Willems , ]. The novelty of our quasi‐analytical approach lies in the fact that it is extended to account for pollutant interactions and that it is the first to analytically integrate the QUAL‐2E transformation equations in a dynamic system in the context of improving the stability and consistency of CSTR‐based QUAL‐type in‐stream water quality simulators.…”

Impact of Global Warming on Dissolved Oxygen and BOD Assimilative Capacity of the World’s Rivers: Modeling Analysis

“…Because they are limited to a small number of parameters, parsimonious models often provide a means to draw broad general conclusions that can be very difficult to identify with more realistic but highly parameterized models [21] and, in some cases, they can also be preferable for practical model applications [22][23][24]. This follows the tradition of using parsimonious models to understand major facets of the dissolved oxygen problem [2-4] as well as other water-quality problems [22,25].…”

Stochastic Modeling for Coliform Count Assessment in Ground Water

“…Goodness of fit of the models are tested in Table ( we accept the null hypotheses and conclude that the models fit well for the data. Table ( 10) summarizes the proportion of variance in the response variable that can be accounted for by the explanatory variables. Table ( Tables (12) and (13) present the illustration of model validation for well and bore well water sources respectively using 10 % of the collected data.…”