Open Access
Quantification of agricultural best management practices impacts on sediment and phosphorous export in a small catchment in southeastern Sweden
(Elsevier, 2023) Oduor, Brian Omondi; Campo-Bescós, Miguel; Lana Renault, Noemí; Kyllmar, Katarina; Mårtensson, Kristina; Casalí Sarasíbar, Javier; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Agricultural activities contribute to water pollution through sediments and nutrient export, negatively affecting water quality and aquatic ecosystems. However, implementing best management practices (BMPs) could help control sediments and nutrient losses from agricultural catchments. This study used the Soil Water Assessment Tool (SWAT) model to assess the effectiveness of four BMPs in reducing sediment and phosphorus export in a small agricultural catchment (33 km2) in southeastern Sweden. The SWAT model was first evaluated for its ability to simulate streamflow, sediment load, and total phosphorous load from 2005 to 2020. Then, the calibrated parameters were used to simulate the agricultural BMP scenarios by modifying relevant parameters. The model performed satisfactorily during calibration and validation for streamflow (NSE = 0.80/0.84), sediment load (NSE = 0.67/0.69), and total phosphorous load (NSE = 0.61/0.62), indicating its suitability for this study. The results demonstrate varying effects of BMP implementation on sediment and phosphorus (soluble and total) export, with no significant change in streamflow. Filter strips were highly effective in reducing sediment (−32%), soluble phosphorus (−67%), and total phosphorous (−66%) exports, followed by sedimentation ponds with −35%, −36%, and −50% reductions, respectively. Grassed waterways and no-tillage were less impactful on pollutant reduction, with grassed waterways showing a slight increase (+4%) in soluble phosphorus and no-tillage having a minimal effect on sediment (−1.3%) and total phosphorus (−0.2%) export. These findings contribute to the ongoing efforts to mitigate sediment and nutrient pollution in Swedish agricultural areas, thereby supporting the conservation and restoration of aquatic ecosystems, and enhancing sustainable agricultural practices.
Open Access
Evaluation of the impact of changing from rainfed to irrigated agriculture in a mediterranean watershed in Spain
(MDPI, 2023) Oduor, Brian Omondi; Campo-Bescós, Miguel; Lana Renault, Noemí; Alfaro Echarri, Alberto; Casalí Sarasíbar, Javier; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
The conversion of cultivated areas from rainfed to irrigated agriculture alters the watershed’s hydrology and could affect the water quality and quantity. This study examined how streamflow, nitrate load, and nitrate concentration changed after irrigation implementation in a Mediterranean watershed in Navarre, Spain. The Soil Water Assessment Tool (SWAT) model was applied in the Cidacos River watershed to simulate streamflow and nitrate load under rainfed conditions. The simulated outputs were then compared with the post-irrigation observed values from mid-2017 to 2020 at the watershed outlet in Traibuenas to determine the irrigation impact. The model calibration (2000–2010) and validation (2011–2020) results for streamflow (NSE = 0.82/0.83) and nitrate load (NSE = 0.71/0.68) were satisfactory, indicating the model’s suitability for use in the watershed. A comparison of the rainfed and post-irrigation periods showed an average annual increase in streamflow (952.33 m3 ha−1, +18.8%), nitrate load (68.17 kg ha−1, +62.3%), and nitrate concentration (0.89 mg L−1 ha−1, +79%) at the watershed outlet. Irrigation also caused seasonal changes by altering the cropping cycle and increasing the streamflow and nitrate export during the summer and autumn when irrigation was at its peak. The increases in the post-irrigation period were attributed to the added irrigation water for streamflow and increased nitrogen fertilizer application due to changes in cropping for nitrate concentration and export. These findings are useful to farmers and managers in deciding the best nitrate pollution control and management measures to implement. Furthermore, these results could guide future development and expansion of irrigated lands to improve agricultural sustainability.
Open Access
Effects of climate change on streamflow and nitrate pollution in an agricultural mediterranean watershed in northern Spain
(Elsevier, 2023) Oduor, Brian Omondi; Campo-Bescós, Miguel; Lana Renault, Noemí; Casalí Sarasíbar, Javier; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Predicting water quality and quantity response to climate change in a watershed is very difficult due to the complexity and uncertainties in estimating and understanding future hydrological conditions. However, hydrological models could simplify the processes and predict future impacts of agricultural activities. This study aimed to evaluate the applicability of the Soil Water Assessment Tool (SWAT) model for climate change prediction of streamflow and nitrate load in an agricultural Mediterranean watershed in northern Spain. The model was first evaluated for simulating streamflow and nitrate load under rainfed agricultural conditions in the Cidacos River watershed in Navarre, Spain. Then, climate change impact analysis on streamflow and nitrate load was conducted in the short-term (2011–2040), medium-term (2041–2070), and long-term (2071–2100) future projections relative to the historical baseline period (1971–2000) under the RCP4.5 and RCP8.5 CO2 emission scenarios. The model evaluation showed a good model performance result during calibration (2000–2010) and validation (2011–2020) for streamflow (NSE = 0.82/0.83) and nitrate load (NSE = 0.71/0.68), indicating its suitability for adoption in the watershed. The climate change projection results showed a steady decline in streamflow and nitrate load for RCP4.5 and RCP8.5 in all projections, with the long-term projection scenario of RCP8.5 greatly affected. Autumn and winter saw a considerable drop in comparison to spring and summer. The decline in streamflow was attributed to the projected decrease in precipitation and increase in temperatures, while the nitrate load decline was consistent with the projected streamflow decline. Based on these projections, the long-term projection scenarios of RCP8.5 indicate dire situations requiring urgent policy changes and management interventions to minimize and mitigate the resulting climate change effects. Therefore, adapted agricultural management practices are needed to ensure sustainable water resource utilization and efficient nitrogen fertilizer application rates in the watershed to reduce pollution.

Campo-Bescós, Miguel

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