Efficiencies of best management practices in reducing nitrate pollution of the Sebdou River, a semi‐arid Mediterranean agricultural catchment (North Africa)

Abstract

A major problem facing the water sector in Algeria is deteriorating water quality, which is strongly influenced by nutrient inputs to agricultural watersheds. To mitigate the effects of agricultural activities and enhance water quality, this study considered the impact of different best management practices (BMPs) in agriculture. The objective of the research was to evaluate the impacts of various agricultural BMPs on nitrate losses in the Sebdou catchment in north-west Africa using the Soil and Water Assessment Tool (SWAT) model in order to identify and recommend the most appropriate BMP. The study was carried out in two parts: first, the SWAT model was calibrated and validated to simulate discharge and nitrate losses at the outlet of the catchment, and second, the calibrated model was used to assess the effects of BMPs on nitrate losses. The hydrological modelling fitted well with the observed data for the calibration and validation periods (NSE between 0.63 and 0.65 and R 2 between 0.80 and 0.92). Nitrate simulation was also satisfactory (NSE = 0.58 and R 2 = 0.58), with the average nitrate exports at the outlet varying between 136 and 149 t N year À1 . Agricultural tillage practices were the main N input and plant uptake was the main N output. The simulation results of BMP scenarios (contour farming, strip cropping and terracing) showed a significant decrease in nitrate quantity in soil, nitrate yield in surface run-off and nitrate exports. The maximum reduction was observed from the use of parallel terraces, which reduced nitrate in soil by 17% (41 kg ha À1 ) and decreased nitrate flux exportation to below 133 t N year À1 (a reduction of about 11%). This study provided useful information for implementation of the most effective agricultural BMPs in the catchment for stakeholders who are interested in soil and water management.

Assessing Soil Erosion Dynamics in the Rmel Watershed, Northern Morocco by Using the Rusle Model, Gis, and Remote Sensing Integration

“…Each measure has a protective degree, with its coefficient determined by how well it minimizes runoff and mitigates erosion causes (Benzougagh et al 2020). Cultivation practices such as contour farming, alternating strips or terraces, reforestation on terraces, and ridging are identified as highly effective soil conservation strategies (Zettam et al 2022). These strategies are evaluated based on the soil loss ratio with specific support on agricultural land compared to the corresponding loss with parallel slope plowing (Zouagui et al 2018).…”

Exploitation of Magnetic Susceptibility Data for Soil Stability Analysis: A Watershed Study of the Oued Ghiss Dam in the Central Rif, Morocco

“…Water erosion is a natural phenomenon with significant environmental consequences, gradually leading to the removal of the topsoil layer and a reduction in agricultural productivity [1], [2].…”

Modeling the impacts of best management practices (BMPs) on pollution reduction in the Yarra River catchment, Australia

“…BMPs are shown to be a successful approach to limit water contamination in various catchments across the world, including those in Spain (Puertes et al 2021), China (Liying et al 2021;Ji et al 2022), North Africa (Zettam et al 2022), and Lithuania (Plunge et al 2022). For instance, Zettam et al (2022) discovered that the largest nitrate reduction would occur if parallel terraces were applied in a semi-arid agricultural catchment, while Plunge et al (2022) found that in Lithuania, TN pollutant reduction can be maximized with BMP's implementation. These results show that the deployment of diverse BMPs can be used to reduce TN, TP and sediment pollution across regions with varying climatic conditions, as demonstrated by different simulations.…”