D. Lohmann

Tison Award 1999

Dag Lohmann received the1999 Tison Award

The 1999 Award was presented to Dr Dag Lohmann in a Plenary session of IAHS during the IUGG Assembly at Birmingham. The following citation was written by Dr Slobodan Simonovic, Chair of the Nominations Committee, and presented on his behalf by Dr Zbigniew Kundzewicz:

Dr Dag Lohmann is the recipient of the 1999 Tison Award for his papers:

(a) Regional scale hydrology: 1 Formulation of the VIC-2L model coupled to a routing model; and

(b) Regional scale hydrology: 2 Application of the VIC-2L model to Weser River, Germany;

both co-authored with N. Raschke, B. Nijssen and D. P. Lettenmaier and published in Hydrological Sciences Journal, vol. 43, no. 1, 1998.

Dr Lohmann’s papers present the two-layer variable infiltration capacity (VIC) macroscale hydrological model. The VIC model is a hydrologically-based soil vegetation atmospheric transfer scheme designed to represent the land surface in numerical weather prediction and climate models. It is coupled to a linear routing mechanism which is optimized with observed precipitation and streamflow data and is derived independently from the VIC model. This work allows utilization of streamflow measurements for the validation of coupled atmospheric–hydrologic models. The VIC model was implemented in the Weser River basin on a rotated grid, compatible with regional weather forecast and climate model, a joint project of the German Weather Service, GKSS Research Centre and the Max Planck Institute for Meteorology. The resulting predictions compare well with observations at daily, monthly and annual time scales. Contrary to earlier papers of other authors published in the hydrological literature, the accuracy of hydrological simulations via an atmospheric model in Dr Lohmann’s work is quite good, rendering the approach promising for practical applications.

Dr Lohmann has the degree in Physics from Georg August University and a PhD degree from Hamburg University. Through his background in high-energy physics and acoustics Dr Lohmann got exposure to linear system theory which he enjoys applying to hydrology. In his own words: "although this can be seen as very old fashioned, I like the idea of simple models, which capture the main characteristics of a system". His work is among first efforts to include (well-known) hydrological techniques into the land surface modelling community (where the majority of people are meteorologists). Traditional hydrological modelling is involved with solving water balance equations (while sometimes the energy balance equation has been neglected), while meteorologists had a higher interest in energy balance equations (not giving adequate attention to the research conducted by hydrologists). There was (and still is) a need to incorporate more realistic hydrological models in weather prediction and climate models, and that is the major subject of Dr Lohmann’s work and the two award winning papers. His contribution comes down to including better parameterizations for the upper and lower boundary condition of water fluxes into the land surface, while keeping the energy balance part of the models (which is superior to the one by traditional hydrological models).

Dr Lohmann has demonstrated his ability to work on collaborative projects and his capacity to work in a strongly multidisciplinary environment. It is our strong believe that the papers published in Hydrological Sciences Journal by Dr Lohmann and his collaborators are an important contribution in the challenging new domain of large-scale hydrology. Macroscale hydrological modelling is a strong growth area worldwide. By bestowing the 1999 Tison Award for papers by Dr Lohmann et al., IAHS offers its support to the research in this area.