摘要
An infiltration and salinity transport model (ISTM) based on the HYDRUS modeling platform was developed to support the beneficial use of treated coal seam gas (CSG) water to irrigate perennial forage plots in eastern Australia. The ISTM was used to support the expansion of irrigated areas under the CSG industry’s first specific irrigation beneficial use approval issued by the Queensland environmental regulatory administering authorities in March 2009. To support meeting regulatory requirements for expansion beyond the original irrigation area, forward modelling within the vadose zone was used to evaluate the fate and transport of the irrigation water as it migrates through the shallow soils and unsaturated bedrock toward the saturated zone; simulations beneath three agricultural systems with contrasting infiltration capacities were assessed. The model simulation results were used to guide irrigation activities to maximize water use in the readily available soil water capacity range for these agroecosystems, without detrimental impacts to plant growth or surface water/groundwater and soil resources. In this paper, a practical irrigation and rainfall systems-driven hydrogeochemical conceptual model is presented to identify processes that are likely to govern infiltration from the land surface, root water uptake, and solute transport into, and potentially through, the unsaturated zone. A numerical model is then parameterized to represent the primary processes hypothesized to affect water and salinity movement in the vadose zone. Finally, a series of simulations, conducted to identify the key parameters and processes governing the potential movement of water and salt through the root zone and into the bedrock vadose zone, are discussed. The simulations are used to support continuous improvement in modeling approaches for sustainably managing treated CSG extraction water allocated to irrigation.