Comparison of modelling approaches to estimate trapping efficiency of sedimentation basins on peatlands used for peat extraction

Abstract

Peatlands on which there is vacuum peat harvesting must be drained to allow peat extraction. Peat erosion due to mechanical tilling, vacuum harvest and rain can generate large suspended sediment concentrations that must be reduced before reaching the receiving waters. In this study, six sedimentation basins were monitored over one or two ice-free seasons, resulting in seven basin-years time series, to estimate their trapping efficiency. Using these data, two modelling approaches were first applied to predict the seasonal trapping efficiency of the basins, namely the Brown equation and a multilinear regression model (MLR). Secondly, an additional approach based on the hydrodynamic model MOHID was used to compute the trapping efficiency of one of the basins for a single rain event. The Brown equation, used worldwide in agricultural sedimentation pond, proved to be less efficient in predicting the trapping efficiency of the basins (r = 0.67, p = 0.1, leave-one-out RMSE = 47.2%) than a MLR model using the volume of the basin, the surface of the harvested catchment and the Von Post decomposition degree of the peat as predictors (r = 0.87, p = 0.01, leave-one-out RMSE = 31.6%). The deterministic MOHID model was capable of reproducing high flow suspended sediment concentration at the basin outlet, based on measured settling velocity distribution of the peat through ViCAs protocol, but requires a good description of the settling velocity distribution across multiple hydrological conditions to simulate the suspended sediment concentrations over a full season in order to compute trapping efficiency. The results presented here provide new insights on eroded peat modelling and could lead to better design formulas for basin conception.

Study of the hydrological impact of the growth of a residential neighborhood on urban drainage – A case study at the city of Macaé, Rio de Janeiro, Brazil

“…The MOHID platform has several computational resources to model hydrodynamics, hydrology, substance transport, considering the phenomena of interest to researchers, and with the possibility of adopting different formulations depending on the application. More specifically, dealing with the case of interest for this study, MOHID LAND can be used to simulate surface runoff and water infiltration into the soil (Junior, Costa & Rodrigues, 2016;Simionesei et al, 2016;Campos et al, 2017;Paiva et al, 2017;Garneau, Duchesne & St-Hilaire, 2019;Junior et al, 2019).…”

Validation of the 3D-MOHID Hydrodynamic Model for the Tagus Coastal Area

“…The versatility and flexibility of the MOHID Water eases its implementation in any type of system and to accomplish different modelling requirements depending on the objectives of the work to be performed. Indeed, in the last four years the MOHID Water was applied in multiple studies worldwide, namely in Canada [13], Colombia [14,15], Brazil [16], Argentina [17,18], Uruguay [19], Holland [20], France [21], Spain [22], Croatia [23], Australia [24,25], Malaysia [26] and Korea [27]. In Portugal, this model has been implemented in the entire Portuguese coast [28][29][30] and in all main estuaries [31][32][33][34][35].…”