Predicting the interactions between rivers and groundwater pumping

Abstract We summarise research that the eWater Cooperative Research Centre is carrying out incorporating groundwater-surface water interaction capabilities into the next generation of river management tools being developed for Australia's large river basins. We describe three simplified modelling approaches that are currently in development: (i) a reach scale 'Groundwater-Surface Water Link' model, which operates as a groundwater link to river models and accounts for interactions at the river-reach scale; (ii) a sub-reach scale 'Floodplain Processes' model, which dynamically models bank storage, evapotranspiration, and floodplain inundation. It enables more refined modelling of groundwater-surface water interactions, and can be linked to ecological response models; and (iii) a catchment scale model that estimates the surface and sub-surface flow components to streams

Global modeling of tropospheric iodine aerosol

Natural aerosols play a central role in the Earth system. The conversion of dimethyl sulfide to sulfuric acid is the dominant source of oceanic secondary aerosol. Ocean emitted iodine can also produce aerosol. Using a GEOS-Chem model, we present a simulation of iodine aerosol. The simulation compares well with the limited observational data set. Iodine aerosol concentrations are highest in the tropical marine boundary layer (MBL) averaging 5.2 ng (I) m −3 with monthly maximum concentrations of 90 ng (I) m −3. These masses are small compared to sulfate (0.75% of MBL burden, up to 11% regionally) but are more significant compared to dimethyl sulfide sourced sulfate (3% of the MBL burden, up to 101% regionally). In the preindustrial, iodine aerosol makes up 0.88% of the MBL burden sulfate mass and regionally up to 21%. Iodine aerosol may be an important regional mechanism for ocean-atmosphere interaction

Impacts of irrigation and dryland development on groundwater discharge to rivers - a unit response approach to cumulative impacts analysis

The influence of irrigation and dryland land-use development has increased groundwater recharge, leading to increased discharge of existing saline groundwater and increased the salt load to adjacent rivers. This paper describes further development of a unit response approach to assess the effect and timing of changes to recharge on groundwater discharge to a river. The unit response approach uses a linearised Boussinesq equation to develop an effectively one-dimensional unit response function for a change in recharge to an aquifer some distance from the river. The Glover and Balmer solution for stream depletion is extended from a point sink to an areal source case, and the effects of both a sloping and a bounded aquifer are considered. This approach can provide approximate lead-in and lag times for the impacts of recharge change on groundwater discharge and salt load to rivers. This approach has been applied to estimate the effects of the development of the Bookpurnong Irrigation Area (Loxton, South Australia), and compared with the existing estimates.Griffith Sciences, Griffith School of EnvironmentNo Full Tex

Spatio-temporal evolution of water-related ecosystem services: Taihu Basin, China

Water-related ecosystem services (WESs) arise from the interaction between water ecosystems and their surrounding terrestrial ecosystems. They are critical for human well-being as well as for the whole ecological circle. An urgent service-oriented reform for the utilization and supervision of WESs can assist in avoiding ecological risks and achieving a more sustainable development in the Taihu Basin, China (THB). Spatially distributed models allow the multiple impacts of land use/land cover conversion and climate variation on WESs to be estimated and visualized efficiently, and such models can form a useful component in the toolbox for integrated water ecosystem management. The Integrated Valuation of Ecosystem Services and Tradeoffs model is used here to evaluate and visualize the spatio-temporal evolution of WESs in the THB from 2000 to 2010. Results indicate that water retention service experienced a decline from 2000 to 2005 with a recovery after 2005, while there was ongoing water scarcity in urban areas. Both the water purification service and the soil retention service underwent a slight decrease over the study period. Nutrients export mainly came from developed land and cultivated land, with the hilly areas in the south of the THB forming the primary area for soil loss. The quantity and distribution of WESs were impacted significantly by the shrinkage of cultivated land and the expansion of developed land. These findings will lay a foundation for a service-oriented management of WESs in the THB and support evidence-based decision making

Significance of the connection between bedrock, alluvium and streams: A spatial and temporal hydrogeological and hydrogeochemical assessment from Queensland, Australia

Catchment-scale hydrological and hydrogeological investigations commonly conclude by finding that particular stream reaches are either gaining or losing; they also often assume that the influence of bedrock aquifers on catchment water balances and water quality is insignificant. However, in many cases, such broad findings are likely to oversimplify the spatial and temporal complexity of the connections between the different hydrological system components, particularly in regions dominated by cycles of droughts and flooding. From a modelling perspective, such oversimplifications can have serious implications on the process of identifying the magnitude and direction of the exchange fluxes between the surface and groundwater systems. In this study, we use 3D geological modelling and historic water chemistry and hydraulic records to identify the origins of groundwater at different locations in the alluvium and along the course of streams in the Lockyer Valley (Queensland, Australia), a catchment impacted by a severe drought (‘Millennium Drought’) from 1998 to 2009, followed by extensive flooding in 2011. We also demonstrate how discharge from the sub-alluvial regional-scale volcanic and sedimentary bedrock influences the water balance and water quality of the alluvium and streams. The investigation of aquifer geometry via development of a three-dimensional geological model combined with an assessment of hydraulic data provided important insights on groundwater flow paths and helped to identify areas where bedrock aquifers interact with shallow alluvial aquifers and streams. Multivariate statistical techniques were then applied as an additional line of evidence to groundwater and surface water hydrochemical data from large historical datasets. This confirmed that most sub-catchments within the Lockyer Valley have distinct water chemistry patterns, which result from mixing of different water sources, including discharge from the sub-alluvial bedrock. Importantly, in addition to the observed spatial variability, time-series hydrochemical groundwater and surface water data further demonstrated that the hydraulic connection between alluvial aquifers, streams and sub-alluvial bedrock aquifers is temporally dynamic with very significant changes occurring at the transition from normal to drought conditions and following flooding, affecting both catchment water quality and water balances

Brokering trust in citizen science

Citizen science (CS) information requires systematic review that incorporates a range of interests and concerns. Yet, there has been little research on what might constitute reviewing best practice to ensure CS is trusted by contributors and users of the data. Insights from a survey of all 1134 reviewers who curate the global eBird Project highlight the knowledge-brokering work involved to ensure CS data are trusted by both citizens and science. Drawing on scholarship focused on key drivers of useable knowledge for natural resource decision-making, we consider CS reviewing best practice to ensure CS can be useful to the producers and users of this knowledge. We find that CS reviewers need to be motivated to provide appropriate feedback to improve CS data, commit to reviewing practice that is respected by citizens, and ensure the information published is credible and be reviewed by a supportive and accountable network of fellow reviewers