Assessing the environmental sustainability of irrigation with oil and gas produced water in drylands

Produced water (PW) is the largest by-product of the oil and gas industry. Its management is both economically and environmentally costly. PW reuse for irrigation offers an alternative to current disposal practices while providing water to irrigators in drylands. The aim of this investigation was to evaluate the environmental effects of irrigation with PW. The SALTIRSOIL_M model was used to simulate the irrigation of sugar beet with 15 PWs of a wide range of qualities in four climates of different aridity and on four contrasting soil types. The impacts on soil salinity, sodicity and pH as well as on crop yield and drainage water salinity were estimated. Well-drained soils with low water content at field capacity (Arenosol) are less sensitive to salinisation while a relatively high gypsum content (Gypsisol) makes the soil less vulnerable to both sodification and salinisation. On the contrary, clayey soils with higher water content at field capacity and lower gypsum content must be avoided as the soil structural stability as well as a tolerable soil electrical conductivity for the crop cannot be maintained on the long-term. Soil pH was not found to be sensitive to PW quality. Drainage water quality was found to be closely linked to PW quality although it is also influenced by the soil type. The impact of drainage water on the aquifer must be considered and reuse or disposal implemented accordingly for achieving sustainable irrigation. Finally, increasing aridity intensifies soil and drainage water salinity and sodicity. This investigation highlights the importance of adapting the existing irrigation water quality guidelines through the use of models to include relevant parameters related to soil type and aridity. Indeed, it will support the petroleum industry and irrigators, to estimate the risks due to watering crops with PW and will encourage its sustainable reuse in water-scarce areas.