From the aquifer to the sea - mapping and quantifying groundwater discharge and nitrate flux and transformations - a review of methods

Abstract

This paper reviews methods available for addressing fluxes of water and nitrate, as well as the process affecting nitrate concentrations in the transition from groundwater to surface water, in a comprehensive tabular compilation. Small-scale methods, typically involving direct measurements, give the most quantitative information, while methods working on a larger scale, e.g. airborne or waterborne techniques, can give information on a larger and, in many contexts, more useful scale, but rarely with appropriate quantification. Bridging the gap may be possible by simultaneously applying large-scale measurements and small-scale direct measurements covering the range of values, using these for calibration.