The Christchurch Harbour Macronutrients Project is one of four consortium projects funded by the NERC through the Macronutrient Cycles Programme. The overall goal of the Macronutrients Programme is to quantify the scales (magnitude and spatial/temporal variation) of Nitrogen and Phosphorus fluxes and the nature of transformations through the catchment under a changing climate and a perturbed Carbon cycle. ‘The catchment’ is defined as covering exchanges between the atmospheric, terrestrial and aqueous environments, with the limit of the aqueous environment being marked by the seaward estuarine margin. The aim of the consortium research project is to better understand the behaviour of macronutrients over a range of temporal and spatial scales including the effect of storm events in the Hampshire Avon and Stour rivers and Christchurch Harbour estuary in Dorset. Data collection spans from October 2012 to January 2017. The Christchurch Harbour Macronutrients Project intensively monitored the river inputs and exchange of nutrients at the estuary mouth as well as looking at sediment re-suspension and the role of phytoplankton in macronutrient cycling within the estuary. By using a number of state of the art continuous monitoring techniques and modelling approaches, the scientists produced an accurate assessment of the impact of nutrients entering the estuary during short term storm increased flows in the two rivers. Previously, most water quality monitoring in rivers and estuaries has taken place at fixed times that are spaced too far apart to capture storms when they occur. This is the first project in the UK to intensively monitor water quality in estuaries using sensors and weather prediction technology to anticipate a storm. The Project PI is Duncan Purdie (Ocean and Earth Sciences, NOC).