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Mathematical modelling by convection-diffusion with reaction of organic pollution in the wadi Mouillah stream, north-western Algeria

Benadda Lotfi, Djelita Belkheir, Chiboub-Fellah Abdelghani

Journal of Water and Land Development

2022

no. 54

26--37

This work describes the behaviour of organic pollutants along the wadi Mouillah watercourse and its main tributaries and their impacts on the Hammam Boughrara dam, located in the NW of Algeria, in the Wilaya of Tlemcen. The use of a database relating to physico-chemical, biotic and hydrological variables, covering the period from January 2006 to December 2009, contributed to the understanding of the spatiotemporal evolution of each variable. The application of a mathematical model of the diffusion by convection-dispersion with a reaction on two characteristic parameters of organic pollution, the biochemical oxygen demand (BOD5) which records values above the norm, with peaks that can reach 614%, and total phosphorus (Ptot), which the concentration is always higher with maxima reaching 53 mg∙dm-3 favouring eutrophication; this made it possible with precision to synthesise the propagation of pollutants in the liquid mass. The results obtained on the waters of Wadi Mouillah are therefore of poor quality; there is a need to set up a rigorous water quality monitoring system, with water treatment and decontamination devices to preserve the water resources. This will allow to contribute to better management of water quality in terms of combating the spread of pollution. Therefore, they can be used to support decisions in the context of sustainable development.

Spatiotemporal Assessment of the Water Quality of the Hammam Boughrara Dam (North-West Algeria)

Djelita Belkheir, Benadda Lotfi

Journal of Ecological Engineering

2021

Vol. 22, nr 11

92--103

In this study, which contains a database covering the period from January 2008 to December 2010, on the water level of the Hammam Bougrara dam located in a semi-arid zone with moderate winter (western Algeria), we focused specifically on the mechanisms of eutrophication as well as the spatial and temporal variation of the physicochemical and biological characteristics of the reservoir. The diagnosis revealed high concentrations of certain elements such as P, PO4, NO3, NO2, NH4, Na+, Ca2+, Mg2+, K+, Cl-, HCO3 – and SO4–2, which characterizes highly mineralized waters with conductivities between 1100 and 1800 S/cm, therefore polluted and selenitic. These waters are rich in nutrients, such as phosphorus and with a slightly alkaline pH (between 7.1 and 9.1) favor the proliferation of organisms such as Chlorophyceae, Cyanophyceae and Diatomophycéeswhich together account 93 57% of the population of algae. This proliferation causes a decrease in transparency and dissolved oxygen which are also signs of eutrophication. This study will adopt a better methodological approach to reduce the number of stations and increase the sampling rate, for a thorough understanding of limnology operation of the dam to ensure its protection. Despite the very high phosphorus inlakes during those years, the symptoms of eutrophication in the reservoir (chlorophyll a.) They are far from achieving the expected levels of extreme loads on the flow-replies Vollenweider. This could be explained by the fact that, upon his arrival for restraint, ortho-phosphate is quickly rendered inaccessible due to algae efficient flocculation means of fine clay particles and a formation hydroxyapatite followed by precipitation. Consequently, one can conclude that it would be necessary to develop and deepen our knowledge of limnology of lakes and reservoirs in temperate climates, especially in arid and semi-arid areas, in order to embed processes in these lakes a general model describing the relationship load-response, similar to that of Vollenweider. The results could help set specific objectives to reduce phosphorus inputs depending on the intended use of the waters and allow better management of water quality in terms of trophic response and in the context of sustainable development and decision support.