Freshwater flows to the sea: Spatial variability, statistics and scale dependence along coastlines

Abstract

Beyond the monitoring of main river flows, the discharges of freshwater from land to the sea are typically left unmonitored along long coastline stretches. This study uses uniquely fine-resolved data and determines the spatial variability and statistics of the freshwater fluxes to the sea along two Swedish coastlines. The flux statistics depend greatly on subjective investigation choices of the support (or aggregation) scale of flux measurement, H, and the coastline length resolution, G. For common H and G values and relations, the flux coefficient of variation ranges from 1.5 to 22.5 and there is around 90-95% probability that locally measured or modelled fluxes miss the high-end fluxes that are greater than the arithmetic mean flux and carry most of the total freshwater discharge across the coastline. Quantification of the inland hydrological balance and its distribution over the whole coastal catchment area is needed for objective guidance of coastal discharge interpretations. Copyright 2008 by the American Geophysical Union.