Roland specialises in researching the movement of water, and transport and transformation of nitrogen, between a parcel of land and the receiving surface water. As defensible cause-effect relationships between land use and water pollution require both, the hydrological pathways and the contaminant transformations occurring along them to be understood, it has been a feature of his work to advance hydrological and biogeochemical research concurrently.

Roland has 20 years of experience working with New Zealand regional councils and primary industry organisations, both through collaboration in government-funded research programmes and through consulting projects.

Roland led the “Transfer Pathways Programme” funded by the Ministry of Business Innovation and Employment from 2015-2018 and now leads its successor programme. This new “Critical Pathways Programme” focuses particularly on unravelling the typically shallow and relatively fast pathways between a parcel of land and a local stream or small river. Roland also contributes to the “Enhanced Mitigation of Nitrate in Groundwater” programme led by Environmental Science and Research (ESR), the “Doubling Diffuse Pollution Mitigation” programme led by the National Institute for Water and Atmospheric Research (NIWA), and the “Sources and Flows” programme of the Our Land and Water National Science Challenge.

He has published over 30 journal articles, contributed to a number of book publications, and is a reviewer for several academic journals including Hydrological Processes; Biogeosciences; Geoderma; Journal of Environmental Quality; European Journal of Soil Science; Agriculture, Ecosystems and Environment.

Roland is an active member of the New Zealand Hydrological Society and the New Zealand Society of Soil Science and sits on the Scientific Advisory Committee of the “Land Use and Water Quality” conference series – assisting in organising the biennial conferences in Austria (2015), Netherlands (2017) and Denmark (2019).

Roland’s research areas include:

• Quantification of pathway-specific transfers of nitrogen and phosphorus from land to surface waters that take lag times and attenuation into account.
• Biogeochemical and hydrological controls on denitrification in the vadose zone-groundwater zone continuum.
• Redox-stratification of groundwater systems.
• Harnessing built and natural nitrogen attenuation capacity to optimise land use patterns.