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Expert's (Expert) career started in soil physics following study of mathematics and physical chemistry and has resulting in him designing instruments for the measurement of soil physical properties. He has also
developed
models for estimating wetting patterns due to trickle irrigation and estimation of drainage when combined with evaporation. He and a colleague have recently written the first method to successful estimate surface
irrigation advance using the linear soil concept.

Expert has a written both papers on the formation and controlling conditions for acid sulfate soils as rates of transport of acidity within these soils. He has also worked on acid sediments and the measurement of
physical properties and modeling of the fluxes of acidity in these sediments. He was the Chairman of the International Working Party on Acid Sulfate Soils and organized a international conference on this topic.

His work on soil gases is highly regarded with a citation classic paper in Soil Biology and Biochemistry on the physical constraints to soil respiration. More recently he and a colleague have developed the first
mathematical solution for oxygen transport to both microbes and roots in soil. This has led to a number of subsequent applications of this work including understanding greenhouse gas transport and generation in soils.
Recently as part of a scholarship he has developed a method for upscaling nitrous oxide fluxes from urine patches to paddock, farm and regional scale.

Expert has used his skills in applied mathematics to model transport processes in soils and sediments, evaporation of water from water bodies, transport of contaminants in groundwater and surface water and to
design land treatment methods for waste water. His wide knowledge of porous media physics and applied mathematics has allow such a diverse application of his skills. He was the research leader for the Catchments
and Climates group in the EWater CRC that developed the SOURCE hydrology model. He developed a model for estimating pesticide contamination in catchments based on upscaling from paddocks using convolution
mathematics. More recently he was employed by the Australian Bureau of Meteorology to write a review of how to couple water quailty models onto the Bureau's existing water quantity models. He also assisted in
developing and writing a funding proposal for this work which has been successful.

Expert developed the mathematical solutions that led to the development of WetUp micro-irrigation software. This build on the work he did in his early career with DSIR on measuring irrigation wetting patterns and
analysis of these. He woprked on the problem of surface ponding with some spray spray irrigation methods to avoid bypass flow and poor irrigation efficiencies.

Negotiated a contract for CSIRO and his firm with BHP Nickel West to model the salt transport in hypersaline waste heaps. This showed which was not realized by BHP that water would pond in the center of the heaps due to there concave conical shape and salt was being lost to the ground water via this route. The surface mineralogy was also measured by CSIRO with Expert managing the process and showed the client that some produces in the water heaps need different management.He was engaged by a client to investigate complete loss of rice crops following irrigation. He searched the literature and proposed a valid hypothesis for the losses due to multiple causes resulting from sedimentation from the irrigation water. He has also advised on how to overcome the problem using a combination of chemical and physical processes to cause sedimentation prior to irrigation. He provided consulting services to Plant and Food Crown Research Centre on denitrification processes in soils. He developed mathematical solutions which allowed analysis of existing data and new models for understanding threshold levels for generation of nitrous oxides.While with CSIRO he work with the Snowy Mountains Engineering Corporation to advise on acid sulfate soils issues associated with the Tugun Bypass tunnel. He developed statistical methods to determine the required sampling frequency of bores and when bores had recovered enough to stop monitoring. He also assisted with design of irrigation methods to flush the acidity from the soils and treat begfore reinjection.The expansion of irrigation in Northern Australia was investigated and he led a team to consider the biophysical aspects of what changes to the water regime would mean. He and this team developed scaling methods to allow objective assessment of benefits and costs, methods for assessing irrigation mosaics and effects of spacing and size and a new solution for groundwater mounding.