Future of Hydrological Research: a global overview András Bárdossy

Introduction The next appearance of Halley’ comet is on July 28, 2061

Introduction The next appearance of Halley’ comet is on July 28, 2061 Will it rain next Monday in Durban?

Introduction Number of raindrops in a small catchment during an event?

Introduction Number of raindrops in a small catchment during an event? 75 km2 (Goldersbach) 12mm in 1 hour = 1013 -1014 raindrops In a line 107 km 10 times Moon and back One cannot predict, model or measure each raindrop …

Observations + Laws = Predictions Incomplete observations Partial coverage Indirect measurements Laws High variability of the parameters Hydrology is not a science to impress – it is a necessity, linked to decision making

Modeling of the water cycle is complicated Mathematical modeling is the art of translating problems into mathematical formulations Limit the model to certain processes geographical areas Assumptions Processes Variables (observations)

Modeling in data rich environments: Focus on the laws and the parameters Modeling in data scarce environments Assembling knowledge and observations There is no single model and method that fits all.

Remotely sensed precipitation

Kokcha river at Khojaghar

Discharge downstream

Kokcha

Water supply of Lima

February snow cover decreases Marca 2007 1999

Elevation model and observations

Action: water transfer from the Atlantic side of the Andes

Rems catchment modeled using WASIM-ETH (Pawan Kumar Thapa)

Surface runoff using different assumptions on unobservable variables Good integral performance with strong differences in the details a) b) c) d)

Remaining 100% difference in surface runoff volume Surface runoff using different assumptions on unobservable variables assuming certain dependencies Remaining 100% difference in surface runoff volume SCE-UA Parameter Para. set 1 Para. set 2 Para. set 7

Areal precipitation from daily interpolation (105 km2 in the Black Forrest)

Summary Incomplete information  uncertainty Uncertainty has to be quantified – reduced if possible Observations Laws (models) – parameters Uncertainty has to be reduced Observations – direct and indirect Scientific advances Design and management for the future Past information Climate change We do not know the present nor the past but would like to know the future.

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