No abstract

Medium resolution satellite data, such as Sentinel-2 of the Copernicus programme, offer great new opportunities for the agricultural sector, and provide insights on soil surface characteristics and their management. Soil monitoring requires a high-quality dataset of uncovered and plastic covered agricultural soil. We developed a methodology to identify uncovered soil pixels in agricultural parcels during seedbed preparation and considered the impacts of clouds and shadows, vegetation cover, and artificial covers, such as those of greenhouses and plastic mulch films. We preserved the spatial and temporal integrity of parcels in the process and analysed spectral anomalies and their sources. The approach is based on freely available tools, namely Google Earth Engine and R Programming packages. We tested the methodology on the northern region of Belgium, which is characterised by small, fragmented parcels. We selected a period between mid-April to end-May, when active agricultural management practices leave the soil bare in preparation for the main cropping season. The spectral angle mapper was used to identify soil covered by non-plastic greenhouses or temporary soil covers, such as plastic mulch films. The effect of underlying soil on temporary covers was considered. The retrogressive plastic greenhouse index was used for detecting plastic greenhouses. The result was a high quality dataset of potential bare uncovered agricultural soil that allows further soil surface characterisation. This offered an improved understanding of the use of artificial covers, their spatial distribution, and their corresponding crops during the considered period. Artificial covers occurred most frequently in maize parcels. The approach resulted in precision values exceeding 0.9 for the detection of temporary covers and non-plastic greenhouses and a sensitivity value exceeding 0.95 for non-plastic and plastic greenhouses.

A mesophilic anaerobic digester, followed by a psychrophilic aerobic post-treatment, was used to treat food waste (FW) with different proportions of fruit and vegetable waste (FVW). Two types of FW were used: low fruit and vegetable mix (LFV, with 56.5% of FVW) and high fruit and vegetable mix (HFV, with 78.3% of FVW). The anaerobic digester fed with LFV failed at an organic loading rate of 1.6 g VS.L.d (volatile fatty acid (VFA) = 6000 mg.L) due to high ammonia (reaching 3000 mg.L). It was shown that, in an unstable anaerobic environment, ammonia is highly correlated ( r = 0.77) with VFA and is negatively correlated with volatile solids, total solids, and chemical oxygen demand (COD) removal rates ( r = 0.88, r = 0.71, and r = 0.91, respectively). In contrast, the anaerobic digester fed with HFV exhibited a stable performance (VFA = 1243 mg.L), with limited ammonia accumulation (940 mg.L). Methane generation was affected by the FVW content and reached 531 ml CH.g VS (CH = 52%) with LFV feed and 478 ml CH.g VS (CH = 57.4%) with HFV. The overall TS, VS and COD removal rates (all ranging between 94% and 97%), were closely similar for LFV and HFV. Accordingly, the aerobic post-treatment seems to compensate for the reduced performance of the disturbed anaerobic system fed with LFV.

No abstract

The quantification and monitoring of sediment dynamics in estuaries has received plenty of attention in recent years due to both economic and environmental interests. Numerical models have been widely applied for predicting the morphodynamic evolution of these areas. However, the degree of uncertainty of these models is often very high due to the lack of measurements necessary for a complete model calibration and validation. In this paper, different methods have been integrated to overcome these limitations. The hydrodynamics and suspended sediment transport in the IJzer estuary were estimated by means of field data and with the use of a two-dimensional hydrodynamic model coupled to a morphodynamic model. Tidal pumping was recognized as the main driving mechanism of sediments inside the estuary. Erosion-deposition areas calculated with the numerical model were compared to the locations and volumes of dredged material. Model results and measurements were generally in good agreement. Additional support for the morphodynamic model results came from airborne hyperspectral images acquired in 2001 and 2005.