East Coast Lows and Water Security

East coast lows (ECLs) can be damaging and costly storms, however they are also important for water security bringing the heavy soaking rainfall that fills dams along the coast and the Tablelands of New South Wales.

Research results

Regional water security over the east coast of NSW is significantly affected by ECL activity, with ECL types determining the timing, location and severity of effects.

The climate of the Eastern Seaboard of Australia is distinct from the rest of south eastern Australia, with little relationship between rainfall in this area and the major drivers of rainfall elsewhere in Australia, such as El Niño-Southern Oscillation.

However rainfall along the eastern seaboard is not homogenous with the region comprising 2-3 sub-regions with similar rainfall characteristics and where the location of ECL types and extent of their impacts are linked.  This means that if ECL subtypes change in the future (due to either natural variability or climate change) then rainfall patterns will also change. For example rainfall events that we have relied on to fill reservoirs over the last 30-50 years may not occur or may occur outside of the reservoir catchments.

ESCCI-ECL Project Results

Regional water security impacts of extreme ECLs on south-eastern seaboard reservoirs

Most publicity about ECLs focuses on the negative and destructive aspects of these storms. But on the positive side ECLs and their associated rainfall are also important for generating significant inflows into major water storages along coastal NSW. This study aims to better understand the hydrologic importance of ECLs and related weather systems for water supply. This information will be used to better understand how water security may be affected if future climate change alters the frequency, intensity, duration and location of ECLs.

The project comprises three sub-projects:

5.1: ECLs: formation, impacts, historical variability and future projections

  • Characterisation of ECL sub-types and their relationship with large-scale drivers of hydroclimatic variability

5.2: Testing the hydrologic validity of downscaled climate data for water security assessment

  • Assessing the ability of using NARCliM data in modelling to replicate hydrology and persistence of runoff that is important in the performance of reservoir systems

5.3: Assessing the impact of ECLs on water security

  • Based on a series of case studies with different ECL impacts (North and South coast)
  • Evaluating how sensitive water resource systems are to changes in ECL behaviour

Research for Project 5 was initiated in 2013 and will be completed in 2016.

References

Chowdhury, A.F.M.K., Lockart, N., Willgoose, G., Kuczera, G. and Parana Manage, N. (2015): Development of a compound distribution Markov chain model for stochastic simulation of daily rainfall with long term variability. Water Resources Research, IN REVIEW.

Twomey, C. and Kiem, A.S. (2015): Spatial and temporal inhomogeneity of rainfall patterns in Australia - why is the eastern seaboard of Australian (ESA) different and why does inhomogeneity also exist within the ESA? International Journal of Climatology, IN REVIEW.

Kiem, A.S., Twomey, C., Lockart, N., Willgoose, G., Kuczera, G., Chowdhury, A.F.M.K., Parana Manage, N., Zhang, L. (2015): Links between East Coast Lows (ECLs) and the spatial and temporal variability of rainfall along the eastern seaboard of Australia (ESA). Australian Meteorological and Oceanographic Journal, IN REVIEW – ESCCI Special Issue.

Lockart, N., Willgoose, G., Kuczera, G., Kiem, A.S., Chowdhury, A.F.M.K., Parana Manage, N., Zhang, L. and Twomey, C. (2015): Case study on the use of dynamically downscaled GCM data for assessing water security on coastal New South Wales. Australian Meteorological and Oceanographic Journal, IN REVIEW – for ESCCI-ECL special issue.

Parana Manage, N., Lockart, N., Willgoose, G.R., Kuczera, G., Kiem, A.S. and Chowdhury, A.F.M.K. (2015): Testing the statistics of dynamically downscaled rainfall data for Upper Hunter Region, New South Wales, Australia. Australian Meteorological and Oceanographic Journal, IN REVIEW – for ESCCI-ECL special issue.

Verdon-Kidd, D.C., Kiem, A.S. and Willgoose, G. (2015): East Coast Lows and the Pasha Bulker storm – lessons learned eight years on. Australian Meteorological and Oceanographic Journal, IN REVIEW – for ESCCI-ECL special issue.

Journal papers in preparation

Twomey, C. and Kiem, A.S. (2015): East Coast Lows (ECLs) and rainfall along the eastern seaboard of Australia (ESA) - comparison of datasets used to record ECL occurrence and impacts on rainfall. Monthly Weather Review, IN PREPARATION.