Evaluation of the Impact of Changing from Rainfed to Irrigated Agriculture in a Mediterranean Watershed in Spain

Brian Omondi Oduor (), Miguel Ángel Campo-Bescós, Noemí Lana-Renault, Alberto Alfaro Echarri and Javier Casalí
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Brian Omondi Oduor: Department of Engineering, IS-FOOD Institute (Innovation & Sustainable Development in Food Chain), Public University of Navarre, Campus de Arrosadía, 31006 Pamplona, Spain
Miguel Ángel Campo-Bescós: Department of Engineering, IS-FOOD Institute (Innovation & Sustainable Development in Food Chain), Public University of Navarre, Campus de Arrosadía, 31006 Pamplona, Spain
Noemí Lana-Renault: Department of Human Sciences, University of La Rioja, 26006 Logroño, Spain
Alberto Alfaro Echarri: Navarre Institute of Agricultural and Food Technologies and Infrastructures (INTIA), Avenida Serapio Huici 22, 31610 Villava, Spain
Javier Casalí: Department of Engineering, IS-FOOD Institute (Innovation & Sustainable Development in Food Chain), Public University of Navarre, Campus de Arrosadía, 31006 Pamplona, Spain

Agriculture, 2022, vol. 13, issue 1, 1-18

Abstract: 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 m 3 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.

Keywords: irrigation; nitrate concentration; nitrate load; rainfed cultivation; streamflow; SWAT model (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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