20 Feb 2007
Photo: Hans Thodsen
During the last 4 years Danish research project CONWOY has examined the influence of climate change on the aquatic environment including river systems and the transport of nutrients. The MIKE 11 Rainfall-Runoff module (RR or NAM) has been used in combination with empirical models in examining the influence of changed hydrological patterns on the transport of diffuse nitrogen and phosphorus. The empirical models distinguish between if the river flow origins from surface-near surface flow or base flow. The HIRHAM regional climate model, projects wetter winter and dryer summers for Denmark in a future climate scenario period 2071-2100 compared to the period 1961-2000. This results in larger amounts of winter surface-near surface runoff in the future scenario period. As the top soils are enriched with nutrients the surface-near surface runoff holds higher nutrient concentrations than the base flow, the river nutrient concentrations are therefore shown to increase up to 50% during winter months, and up to 20% on the mean annual scale.
Photo: Hans Thodsen