Hobe-the Danish Hydrological Observatory.

The Danish hydrological observatory – HOBE – was established in 2007 based on funding from the private VILLUM FOUNDATION (http://www.hobecenter.dk). The Skjern catchment located in the western part of Denmark was selected as the site for the hydrological observatory.

The observatory was established with the overall purpose to obtain a better understanding of the water balance at catchment scale. Previous investigations have documented that water balance closure is difficult to obtain based on measurements of in- and outgoing fluxes at catchment scale due to both measurement and theoretical limitations.

Catchments are subject to a time-space variability of landscape characteristics and the hydrological processes occur and interact across a multitude of spatial and temporal scales. Often fluxes, process understanding and parameters are determined at a smaller scale and a pertinent problem is to scale findings and observations from one scale to another scale and up to catchment scale.

To address these challenges long-term observations and dedicated measurements of in- and outgoing fluxes to and from various hydrological compartments as well as fluxes between compartments are carried out. Dedicated experiments and measurements of parameters and state variables at different scales in the compartments are also performed. Classic state-of-the-art measurement techniques in combination with novel sensor technologies are used to observe and measure the multi-scale spatial and temporal patterns of the land surface and subsurface systems. The observatory takes advantage of the recent developments in ground-based, air-borne and space-borne minimal- and non-invasive meteorological, hydrological, soil physical, hydrogeological, and geophysical sensor technologies. Also measurements of cosmic-ray neutron intensity are used for estimation of soil moisture. The collected data are integrated into a physically based and distributed hydrological model for the catchment.

In the presentation a summary will be given of the results obtained and how the observatory has contributed to the development of a better understanding of the catchment dynamics and of the fluxes between the various hydrological compartments. The water balance closure at different scales will also be addressed.