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Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes the development of a methodology that can be used for determining the spatial and temporal distribution of additional water volumes required to meet a defined groundwater target, such as an historical peizometric surface. The methodology is demonstrated on a case study concerned with mitigating declining groundwater levels in an alluvial aquifer intensively used for agriculture in the Lockyer Valley, Queensland, Australia. The proposed mitigation measure is the importing of large volumes of purified recycled water (PRW) from a large scale indirect potable reuse scheme into the aquifer system. The developed methodology employs both a groundwater flow model together with linear uncertainty analysis. Therefore for the case study, a distributed parameter numerical groundwater flow model was developed for the Lockyer valley alluvial aquifer system using MODFLOW, calibrated to observed groundwater levels, and further constrained by estimates of diffuse and river recharge from water balance studies. The model was used to simulate groundwater levels in the aquifer over a 20-year period. Optimal spatial and temporal distribution of volumes of imported water required to mitigate declining groundwater levels over that period were then estimated, using a modified version of the MODFLOW General Head Boundary (GHB) package. Uncertainty in the predicted import volumes was estimated using linear bayesian analysis principles. The relative worth of data from each observation bore within the groundwater monitoring network was also assessed in terms of the extent to which predictions of import water volumes were made more reliable when furnished with that data. Application of the methodology to the Lockyer alluvial aquifer system illustrated the suitability of the developed methodology for estimating the additional water volumes required for managed aquifer recharge or groundwater substitution schemes in similarly over-exploited aquifers. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater management in irrigation areas requires a comprehensive understanding of the interactions between agricultural management practices and the underlying groundwater resource. Unsaturated zone modelling can be used to predict rates of water and solute movement through the soil profile. By incorporating expert knowledge and measured data, it is possible to investigate the relative influence of management vs environmental factors on water and solute movement. The Agricultural Production Systems sIMulator (APSIM) has been applied to simulate the impacts of both environmental factors and agricultural management factors on deep drainage and nitrate leaching in the Lower Burdekin, North Queensland, Australia. Based on the results of this modelling, predicted annual average deep drainage rates were found to be controlled primarily by soil properties, irrigation scheduling, and, to a lesser extent, annual rainfall. The key factors which were found to control nitrate leaching were: irrigation water quality, fertilizer application rates, soil type, crop management, and irrigation scheduling. However, increases in the concentrations of nitrate in irrigation water resulted in a 64-fold increase in predicted nitrate-leaching rates, compared with a 22-fold increase in predicted nitrate-leaching rates associated with increased fertilizer application rates. As significant quantities of nitrate are predicted to be leached below the root zone, the immediate priority should be to increase monitoring of groundwater quality with a focus on quantifying the transport of nutrients to sensitive receptors. [ABSTRACT FROM AUTHOR]