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Spatial data mapping for reduction of uncertainty in groundwater modelling
Xuyan Wang 1
1. Jacobs, South Brisbane, QLD, Australia
Unbalanced monitoring distribution is always a big challenge in groundwater modelling for assessing the impact of regional groundwater systems on the local human activities. Pilot points as a tool are often used in such groundwater modelling for enhancing information from limit observations but still restricted to the
monitoring data distribution. We propose a novel spatial mapping strategy which combines fuzzy set theory and pilot point approach to form a logic potential from relevant spatial hydrogeological information for reduction of data uncertainty in the model calibration. An effective fuzzy logic approach, which incorporates random probability and fuzzy set theory, is introduced to capture the dispersion of the reliable monitoring information from the relevant regional hydrogeological and monitoring data to produce a map of “intensity” scores which allows the modeller to place “smart pilot points” at locations defined by their probability for producing informative constraints on the statistical distributions of the target variables. The method is demonstrated to be successfully applied for groundwater modelling with limit site monitoring data in a remote mine development project. In summary, the proposed approach intends to reduce the data uncertainty in the groundwater model calibration with the information gleaned from borrowing relevant spatial and
historical data associated with hydrogeological mapping while reducing the site monitoring costs.
Climate Change/Variability Impacts and Water
153 | P a g e Current methods used to estimate trends and status were designed to be applicable to the widest set of bores, thus giving the broadest coverage across Australia. These methods use monthly average groundwater levels to estimate trends and annual average groundwater levels to estimate status. While this approach captures broad trends very well, it can produce undesirable results in some bores, especially where seasonal fluctuations are much greater than long term trend. To address this, the Bureau has developed a methodology which focuses on assessing the trends and status based only on annual recovery peaks. This method automatically identifies recovery peaks during the non-pumping season, and assesses trends and status based on the recent peak against peaks in prior years. However, this method is restrictive in its application as it requires a higher frequency of water level readings for each bore analysed.
Conclusion: By assessing trends and status based only on annual recovery peaks the trends and status are improved, better representing the recovery of the aquifer rather than average values across the year. These improved trends can provide quick, yet accurate, insights into changes in groundwater resources across Australia.
An example of how this has been used to assess the impact of drought in the Murray Darling Basin will be presented. This approach delivers an improved visualisation of changes in groundwater resources across Australia.
Rationalisation of the Shepparton irrigation region public groundwater pump network - an adaptive response to a changing climate
Damien Finlayson 1 , Terry Hunter 2 , Simon Cowan 2 , Rachel Bradshaw 2 1. AECOM, Tatura, VIC, Australia
2. Goulburn-Murray Rural Water Corporation, Tatura, VIC, Australia
Objectives: During the latter part of last century, rising water tables across the Shepparton Irrigation Region (SIR) in Northern Victoria prompted significant public and private investment to manage and control salinity. This investment assumed shallow water tables, and associated salinity threats, would be a permanent feature of the SIR irrigated landscape. One of the many initiatives implemented to combat the salinity threat was the progressive installation of a Public Groundwater Pump network. The resulting network of 115 Goulburn-Murray Water (GMW) owned and operated groundwater pumps provided capacity for water table protection to about 18,000 hectares of horticulture and pasture.
Since the onset of the Millennium Drought approximately 20 years ago, a combination of changes in climate, water use, irrigation practices, land-use and stakeholder expectations has led to a different understanding of the SIR salinity threat. This changed understanding has seen a shift from previously fixed and
prescriptive groundwater and salinity management arrangements to adopting a more adaptive and flexible approach.
Design and Methodology: Consequently, a number of projects, such as rationalising the SIR observation bore network, have already been undertaken by GMW to ensure management of sub-surface drainage assets evolves to meet a more contemporary risk profile and is able to be adapted to foreseeable risk scenarios. GMW’s network of public pumps is now being rationalised to around 32 active pump sites. Water table trends are monitored to ensure pumps can be readily reactivated if high water tables and salinity threats return. Ongoing salinity risk surveillance and reporting will
continue, primarily through a web-based portal designed to better inform landholders about salinity threat changes.
154 | P a g e Original data and results: The public pump rationalisation project, as with other recent initiatives, stems from a need to respond to significant climatic and landscape changes. Importantly, rationalisation of the public pump network is supported by sound science about changing water table behaviour and salinity threats. The project is also responding to significant changes in irrigation and is strongly aligned with community expectations.
Conclusion: There is now a clearer understanding that long-term regional prosperity and resilience requires management responses that adapt to change and address uncertainty. The SIR Public Groundwater Pump Rationalisation project is clear example of recognising the value of important infrastructure and adapting its operation to changing circumstances.
Climate change adaptation: Protecting and expanding freshwater lens resources during land reclamation on low lying islands
Phil Hayes 1 , Simon Liddell 2 , Samuel Watkin 2 1. University of QLD, Brisbane, QLD, Australia 2. Jacobs, Brisbane, QLD, Australia
Sea level rise due to anthropogenic climate change is an existential threat to low lying Pacific islands and their inhabitants. The Island of South Tawara is the capital and main hub for the Republic of Kiribati and home to around 50,000 people, half of the Kiribati population. The island is low lying, with a maximum elevation 3 m above mean sea level, meaning most of the 15 km2 island and its freshwater lens water supply are at risk of ocean overtopping and inundation. A climate change adaptation proposal has recently been funded by the New Zealand government looking to provide around 3 km2 of reclaimed land at a higher elevation by dredging and pumping lagoon sand onto a tidal flat area. The land reclamation offers secure additional land for habitation and in the long term the possibility to expand the area of freshwater resource. However, during construction pumping of seawater and sand threatens existing freshwater.
An existing variable density groundwater model of the freshwater lens system was adapted to investigate the period during and after construction. Transient 3D simulations of the existing lens and reclamation area were completed using the variable density code Modflow USG-Transport. Risks to existing freshwater resources during construction can be mitigated by phased placement of dredged material and appropriate drainage. The time taken for freshwater resources to develop under reclaimed land depends heavily on future rainfall and groundwater recharge. It is estimated to take multiple decades such that other freshwater sources will be required for new housing in the short and medium term.
Application of MAR technology in Sri Lanka
Craig Flavel 1 , Andrew Telfer 1
1. Water Technology, Fullarton, SA, Australia
Despite Sri Lanka’s rich history of water capture and reuse since 414 BC,
technological advances and social changes after the 1970s has seen water supply become insufficient to meet the demand. Shortages of water impact all groundwater uses, from irrigation to potable supply.
155 | P a g e Managed aquifer recharge (MAR) is a proven technology that stores water in aquifers for reuse. This project, undertaken on behalf of Australian Water Partnerships and funded by DFAT, responds to a request by the Water Resources Board of Sri Lanka (WRB) to identify the preferred locations that might be considered for a MAR trial to prove the application of MAR technology in Sri Lanka.
The methodology to gather sufficient information for a trial began with a national level review of shortage, source water and hydrogeology followed by more detailed reviews in the preferred locations. In partnership with local organisations, the
national review identified an abundance of source water and the presence of aquifers of various quality in all ten of the Districts with a shortage, however, the three
Districts with the greatest water shortage was identified by the WRB as Puttalam, Moneragala and Vavuniya. Water Technology matched data from source water
availability and the presence of suitable aquifers with a MAR technology that could be supported by a future scheme operator. Local partners provided a national
stakeholder analysis to assist with this process. Suitable aquifers were characterised by sufficient storage and permeability identified from studies, field investigations and remote sensing.
Analysis of the findings presents estimates of water volumes and qualities that could be provided by a MAR scheme to meet the demand. This includes estimates of the costs for delivery of a trial MAR scheme, the key uncertainties and suggestions for successful management. Positive results from a trial are anticipated to enable wide- scale adoption of the MAR technology in Sri Lanka to address a range of water shortages.
Impact of climate change on the groundwater resources of India: need of an appropriate adaptation strategy
Shadananan Nair Krishnapillai 1
1. Centre for Earth Research and Environment Management, Kochi, Kerala, India
Availability of reliable groundwater in India is fast decreasing as a result of climate extremes and human impact on the environment. Dependency on groundwater increases with rising water demands and depleting surface water resources. Higher temperatures produce more evaporation from surface water bodies and also make the soil dry, reducing the recharging of underground resources. Increasing rainfall seasonality allows wasteful runoff and reduces the duration of groundwater recharge.
High intensity rainfall erodes topsoil, reducing the water holding and recharging capacity of the surface. Trends in rainfall in the dry zones increase dependency of groundwater for irrigation where there is no balance between extraction and
recharge. Changing frequency and intensity of cyclones increasingly salinates coastal aquifers. Predicted change in sea level may add to this in future. Changes in the course of rivers as a result of flooding and sedimentation may lower the water table in the heavy rainfall regions. Falling water availability leads to social issues such as migration of farmers, conflicts over allocation and pricing. Present study analyses the trends in rainfall, temperature and aridity, proneness to droughts, their impact on groundwater resources, and critically reviews the existing policies, strategies and management practices. Current availability and utilisation of groundwater in different States, and the possible changes under an altered climate have been assessed. Main objective of the study is to assess the present groundwater situation in India and its possible changes in near future to suggest guidelines for appropriate groundwater policy and climate change adaptation strategy in the agriculture and water sectors.
156 | P a g e Necessary data have been procured from the India Meteorological Department;
Ministry of Water Resources and Ministry of Agriculture. Study reports from various Research Institutes, Universities and NGOs have been used. Study reveals a sharp decline in groundwater availability in almost all parts of India. Groundwater across north-western and south-eastern India drops by 4cm/year and more than 109 Km3 of groundwater disappeared in 4 years. Quality of groundwater in more than one-third of India is very bad. Urgent measures to cope with changing climate are vital in maintaining food and water securities and poverty alleviation.
Future scenarios for reliability of community groundwater supplies in East Sumba, Indonesia – a karst savanna case study
Penelope B. Godwin 1
1. Charles Darwin University, Rivett, ACT, Australia
Abstract unavailable
Rising water levels in the Burdekin groundwater management area
Amy L. Becke 1
1. Department of Natural Resources, Mines and Energy, Ayr, QLD, Australia
The Burdekin Groundwater Management Area (BGMA), is part of an extensive alluvial aquifer associated with the lower Burdekin River. It supports approximately
35,000ha of irrigated agriculture and drains to the Great Barrier Reef. Since the construction of the Burdekin Haughton Water Supply Scheme (WSS) in the late 1980’s, groundwater levels have risen by up to 10m. Water-tables within 1m of the land surface have been recorded in some areas, posing a significant threat to agricultural production. The WSS allows water to be pumped from the Burdekin River and delivered to farms via open channels, irrigation runoff is removed by a separate drainage network. Recharge to the aquifer is identified to be by rainfall, irrigation deep drainage, losing streams, and leakage from the channel supply system. Discharge mechanisms from the aquifer include coastal outflow,
abstraction, gaining streams and evapotranspiration from groundwater dependent ecosystems (McMahon et al., 2012).
Hydrograph analysis (Ferdowsian & Pannell, 2009) was used to determine whether groundwater levels in the area have reached a new equilibrium. An investigative water balance approach was then used to determine why water levels have stabilised in some areas.
An equilibrium has been reached in the coastal sections of the BGMA, primarily through increased discharge, as the water-table has risen and intersected the surface water drainage. The drains act as either gaining or losing watercourses at times. While groundwater levels have stabilised to a height that may mitigate the risk of waterlogging during years of average rainfall, periods of above average rainfall and flooding would result in an exceptionally high-water table, with major implications for agricultural production. Further, the quality of the groundwater entering the drainage system, and discharging to the Great Barrier Reef lagoon is of major concern (Vardy et al., 2015). The risks associated with these two issues suggest that additional management of the groundwater table is needed.
157 | P a g e Water levels further inland in less transmissive sections of the aquifer continue to rise with increasing risk to agriculture. There is potential that the drainage network will have less of an impact in stabilising the water-table in this area due to lower transmissivities in the aquifer. Elevated water levels will result in increased
salinisation and waterlogging which may have an irreversible impact on agricultural production.
These findings will guide future groundwater management decisions in the BGMA and may be transferrable to other irrigated agricultural areas.
1. Bennett, R. L. 2013. Burdekin Groundwater Management Area-Rising Water Tables, Part A- An estimate of the Impacts of Irrigation and Water Distribution Activities on Groundwater Levels, 2002-2010. Department of Natural Resources and Mines, Queensland, Australia.
2. Cook, P. G., Lamontagne, S., Stieglitz, T., Cranswick, R. 2011. A re-evaluation of groundwater discharge from the Burdekin Floodplain Aquifer using geochemical tracers.
National Centre for Groundwater Research and Training.
3. Ferdowsian, R. & Pannell, D.J. 2009. Explaining long-term trends in groundwater
hydrographs. 18th World IMACS / MODSIM Congress, Cairns, Australia 13-17 July 2009.
http://mssanz.org.au/modsim09
4. McMahon, G. A., Reading, L., Foy, Z., Wang, J., Bajracharya, K., Corbett, N., Gallagher, M., Lenahan, M.J., & Gurieff, L. 2012. Development of a hydrological modelling toolkit to support sustainable development in the Lower Burdekin groundwater system:
Conceptualisation of the Lower Burdekin aquifer. Brisbane: Department of Science, Information Technology, Innovation and the Arts, Queensland Government.
5. Smith, A. J. 2008. Rainfall and irrigation controls on groundwater rise and salinity risk in the Ord River Irrigation Area, northern Australia. Hydrogeology Journal (2008) 16: 1159–
1175. Doi: 10.1007/s10040-008-0301-6.
6. Smith, A. J., Pollock, D. W. & Palmer, D. 2010. Groundwater interaction with surface drains in the Ord River Irrigation Area, northern Australia: investigation by multiple methods.
Hydrogeology Journal (2010) 18: 1235-1252. Doi 10.1007/s10040-010-0596-y.
7. Vardy, S., Turner, R.D.R., Lindemann, S., Orr, D., Smith, R.A., Huggins, R., Gardiner, R.
and Warne, M.St.J. 2015. Pesticides and nutrients in groundwater and their transport to rivers from sugar can cropping in the lower Burdekin. Department of Science, Information Technology, Innovation and the Arts, Brisbane.
Climate resilient urban water security by recharge techniques
Jagannatha Venkataramaiah 1 , Shashankar Anantharaimaiah 1 , Mohammed Inayatulla 1
1. Civil, Jain University, Bengaluru, Karnataka, India
As a part of an ongoing PhD work, Climate Resilient Water Security Urban
settlements demand climate resilient strategies and action plans to ensure a secured water management for Bengaluru Urban region, India was undertaken.
Comparative analysis was conducted, UN reports that since 1900, natural disasters including intense flooding have quadrupled from 50 per year to 200 per year. A definite climate resilient action plans in cities around the world are available. These initiatives have demonstrated definite vision, agenda and action plans specific to each of the cities. Case Studies of four urban settlements Guarulhos (Brazil), Arequipa and Lima (Peru) and Durban (South Africa) reveal transition, structural changes for delegation of responsibilities on water security and its management.
Literature survey was conducted.
Data was collected from the analysis of the relevant case studies and field visits. These global practices are relevant to over 277 Urban Local Bodies in Karnataka of which only 54 towns have Under Ground Drainage and Sewage Treatment Plants. A study of Bengaluru are reported in this paper.
158 | P a g e Conclusively, Studies using Survey Maps and Satellite Imageries during 1900 to 1985 reveal a trend of lowered ecological planning in development plans. In the recent past over 300 urban water bodies are of focus for conservation strategies at Bengaluru Urban Region. Hydrogeological investigations reveal that the ground water resources are contaminated. Dynamic Ground Water Resources investigations
emphasis appropriate attention as there is a decline of ground water resources. In this presentation hydrogeological conditions of Bengaluru Urban Region climate and rainfall, Geological Succession, soil and ground water condition, seasonal, ground water levels and Quality, Estimation methodology are reported. Non-Monsoon recharge from rainfall computed by RIP method is discussed. Water Chemistry interpretation Techniques are introduced. Climate resilient structural changes for Bengaluru Urban water security are identified and reported. Comparison between four global urban regions and Bengaluru case are compared and found that the inadequacy in planning and urban design need to be addressed. State of the art remote sensing techniques in assessing ground water at Bengaluru urban and action plan reveal an endangered ground water security.