Importance of calibration for mathematical modeling of self-purification of lotic environments

Abstract

Aim To demonstrate the importance of calibration in mathematical modeling of self-purification in lotic environments, this study simulated the behavior of various parameters in a river with average annual flows between 4.0 and 32.0 m3.s-1, in a segment downstream from the entry of treated wastewater from a sewage treatment station (average monthly flow of 2.1 m3.s-1). Methods Numerical solution by finite difference of the advection-diffusion equation was used to study the dispersion and to quantify and monitor the evolution over time of the parameters DO, BOD5, Ptotal, NH3, NO3- and the levels of the heavy metals cadmium, chromium, copper, lead and zinc. The longitudinal behavior of the water quality parameters simulated by calibrating the state variables was compared with the behavior of the same parameters simulated via state variables available in the literature. The sensitivity of the state variables was also analyzed. Results The calibration process led to good fits between the simulated and actual data for all the parameters analyzed. On the other hand, the comparison of the water quality model using calibrated state variables with the model based on state variables obtained in the literature revealed inconsistencies regarding the parameters DO, Ptotal, ammonia, nitrate and all the heavy metals. Conclusions Considering the wide threshold ranges of the state variables in the literature and the dearth of studies on calibrating the coefficient of decay and quantifying the release of heavy metals by bottom sediment, this study can serve as a base for future investigations in lotic environments with similar hydraulic and water quality characteristics.

Calibration of mathematical water quality modeling in a river basin under critical conditions

“…Due to scarcity of studies on the Lambari River and the difficulty in comparing the calibrated coefficients obtained in this body of water, the present study compared these coefficients with other studies and, preferably, with those that presented similarly in the flow of the river (2.64 m 3 /s) during the dry season. In this way, Salla, Fernandes, Pereira, Silva Jhunior, and Lima (2016) simulated in a water course with domestic sewage discharge with pollutant load close to the present study and adopted the same values of the literature range in the Uberabinha River, in Minas Gerais for parameters k N,oa , k N,ai , and k P,oi . By observing the coefficients calibrated by Salla et al (2016), there are similarities for k N,ai , k N,in , and k P,oi , in which the values obtained by the authors were k N,ai = 0.40 to 0.90 day −1 ; k N,in = 0.00 to 0.05 day −1 ; and k P,oi = 0.00 to 0.80 day −1 .…”

Utilisation des services écosystémiques pour la définition de seuils de rejets des eaux usées industrielles. Vers un outil d’aide à la décision pour les entreprises.

“…De nombreux modèles existent pour représenter le fonctionnement des écosystèmes : SIMCAT, TOMCAT, QUAL2E, QUASAR, POLMOD.PEST, RIVE, SENEQUE parmi d'autres (Whitehead et al, 1997 ;Pykh, Malkina-Pykh, 1997 ;Tabuchi et al, 2012). Mais ces modèles ne prennent pas tous en compte les mêmes paramètres pour la mise en équation des procédés de transformation, ni les mêmes procédés et, dans l'ensemble, il n'y a pas de prise en compte des composés chimiques, métaux… Par rapport aux paramètres ceux -ci sont nombreux et peuvent varier dans des fourchettes importantes, ce qui peut entrainer des résultats de simulation relativement éloignés des valeurs réelles (Salla et al, 2016). Cela nécessite, si l'on veut obtenir des résultats plausibles de les caler à partir de mesures réalisées sur le cours d'eau que l'on veut étudier (Salla et al 2015).…”

Дослідження Процесів Самоочищення Правих Приток Річки Свічі Басейну Дністра

“…У наукових працях багатьох учених (Arkhypova & Pernerovska, 2015;Korchemlyuk, 2015;Karpets, 2014;Proskurnyn, 2015;Malovanyy et al, 2016;Oshurkevych-Pankivska, 2016;Jakubínský, 2014;Salla, 2016;Swain & Sahoo, 2017;Zaharia, 2017) та ін. досліджено фізичні, хімічні та біологічні процеси, що відбуваються у водних екосистемах.…”