Weather forecasting is a well-established activity, which has been servicing the public for more than a century.  More recently, developments in operational hydrography, hydrology and ecology have made it possible to produce water forecasting even for ecological variables. Since June 1 2001 DHI has been running a comprehensive water forecasting system, the scope of which is presented below.

The Water Forecasting System

The water forecast describes the hydrography and water environment of the Baltic Sea, the Danish Belts & Straits and the North Sea  in a twice daily 5-days forecast.

At present, the water conditions are described in a basic grid with 9 nm. In the waters around Denmark the resolution is 1-3 nm with a vertical resolution of 1 m. The zooming facility gives an overall view of the entire North Sea and Baltic Sea as well as close views of coastal areas, bays and estuaries. Numerous finely resolved sub-models are now running operationally. Alarms for oil spills and for bathing water quality are also included.

DHI has about 25 clients using its forecast on a subscription basis.

Water Forecasts

DHI has developed software tools which can model hydrodynamics, advection/dispersion and numerous biological and chemical variables in 3 dimensions to the desired resolution.

The models are combined with data collected regularly from the area and with meteorological forecast to provide water forecasts of the critical variables. Water forecasts are feasible within these areas:

• Algal blooms. Toxic algal blooms are known to be critical for many water users. The blooms are most likely chaotic phenomena and thus unpredictable for long time scales. For short time scales, days, maybe even weeks, the blooms can be predicted using data from the area in view. Frequent data of algal composition (for example by fluorescence or pigmentation analysis) will reveal the occurrence of toxic algal species in minute quantities when in a pre-bloom condition. The model can calculate the time needed for the algae to reach toxic concentration levels. Surface patches of algae exposed through satellites and/or air surveillance can be routed in time and space to forecast when they will reach a critical area.
• Physical exposure. The models can forecast waves, water levels and current directions and velocities. Extreme values can impact the users in numerous ways.
• Changes in water quality. The forecast includes temperature, salinity, oxygen and chlorophyll.

DHI has installed similar water forecasts in other parts the world, the most prominent being the Sea of Chiloe in Chile for Intesal: www.waterforecast.com/intesal

Access to the Water Forecast

The URL is: www.vandudsigten.dk  and in English: www.waterforecast.com  

Please contact DHI for a test user subscription. E-mail: vandvagt@dhi.dk