Anomalies in the Meuse/Moselle behaviour. Or how to model flood events

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Elinor Phillips
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1 Anomalies in the Meuse/Moselle behaviour Or how to model flood events

2 by: Hubert H.G. Savenije Professor of Hydrology, Delft University of Technology Chair National Committee for IAHS, The Netherlands Chair National Committee of Unesco-IHP, The Netherlands Chair of the Netherlands Hydrological Society (NHV)

3 Anomaly? Similar anomaly in the Moselle/Mosel

5 Conceptual Model

7 Anomaly disappeared Anomaly disappeared by timevariable Lag Time and Evaporation conductivity factor Real evaporation was substantially larger during industrial period of active forestry

8 Is this proof? No, it is an indication that land management is as important as land use in hydrology It shows that forests and agriculture are key to the hydrology (and water quality) of the Meuse

9 What about climate and landuse effects on Floods? Do we understand flood generating processes sufficiently?

10 Threshold processes in Physics Heat transport driven by heating molecular diffusion convective transport turbulent transport boiling Zehe & Sivapalan (2009) HESS

11 trot walk canter gallop

12 Velocity Model gallop walk trot canter Work per unit velocity

13 Knowledge questions We don t fully understand the mechanisms We don t know when a certain mechanism is dominant, or when the switches take place We don t know the triggers for the switches We don t know what happens when the entire system switches into gallop

14 Knowledge questions (2) Rainfall-runoff processes are complex: a multitude of processes, Heterogeneity, need for calibration Equifinality, undeterminable parameters Site specific combinations of processes and properties ('races')

15 A multitude of mechanisms Fenicia et al. (2008) Water Resources Research

16 Huewellerbach 2.7 km 2 Sand stone Vertical mainly Groundwater flow Performance (-) Str. 1 Str. 2 Str. 3 Str. 4 Str. 5 Str. 6 Str. 7 Str. 8 Str. 9 Str Str. 11 Str. 12 Str Str. 14 Str. 15 Number of parameters (-) Str. 16 HBV

17 Weierbach 0.5 km 2 Schist Lateral Steep Rapid subsurface flow Performance (-) Str. 1 Str. 2 Str. 3 Str. 4 Str. 5 Str. 6 Str. 7 Str. 8 Str. 9 Str. 10 Str Number of parameters (-) Str. 12 Str. 13 Str. 14 Str. 15 Str. 16 HBV

18 Wollefsbach 0.9 Str. 1 Str km 2 Marls (eroded) Str. 3 Str. 4 Str. 5 Lateral Rapid subsurface flow / Hortonian overland flow Performance (-) Str. 6 Str. 7 Str. 8 Str. 9 Str. 10 Str. 11 Str Str Number of parameters (-) Str. 14 Str. 15 Str. 16 HBV

19 Topography as a driver Renno et al. (2008) Remote Sensing of Environment

20 Drainage direction: Lateral Lateral Vertical Land use: Grass/wetland Forest Agriculture Soil: Shallow Variable Deep Dominant mechanism: Saturation overland flow Rapid subsurface flow Groundwater flow / Hortonian overland flow

21 Elevation above stream groundwater level Distance from stream wetland hillslope plateau SOF mechanism SSF mechanism DP & HOF mechanisms

22 Three model classes Classes: Wetland Hill slope Plateau Topography flat steep undulating Land use pasture, wetland forest, nature agriculture, pasture Soils shallow shallow deep Dominant mechanism saturation overland flow storage excess sub-surface flow groundwater flow drainage not well-drained well-drained not well-drained drainage direction lateral lateral vertical time scale very fast fast very slow Supporting mechanism groundwater flow groundwater flow infiltration excess flow (during high intensity rainfall) drainage not well-drained not well-drained well-drained drainage direction vertical vertical lateral time scale very slow slow fast

23 E i P Wetland 4 parameters: --D w w --S w,max w,max D w --K w w -β -β w w ( ) P = max P D,0 e w Ew E 0 Q = c P w, sof w e c w 1-c w c w = 1 1 S S w w,max β w S w S w,max Q w, gw = S K w w

24 E i P Hillslope 6 parameters: --D h h --S h,max h,max D h ( ) P = max P D,0 e h --K h h -β -β h h --a --S wp wp E t + E s c h P e a c h P e Q h, rsf c h 1-c h c h = 1 1 S S h h,max β h S h S h,max ( ) 1 a ch Pe C S h,gw Q h, gw = S h, gw K h

25 E i P Plateau 6 parameters: --D p p --K p p D p ( p ) P = max P D,0 e --S wp wp --S u,max u,max --F max max E t 1 Su S wp = Et,0 max,0 P Su,max S wp F Pe F = min, ( P F ) e max Q p, ieo Su S u,max C R S p,gw Q h, gw = S p, gw K p

26 Characteristics of sub-models Model: Wetland Hillslope Plateau Dominant mechanism saturation overland flow rapid sub-surface flow groundwater flow parameters D w [L/T], cc S w, max [L], fc β w [-], fc D h [L/T], cc S h, max [L], fc β h [-], fc a [-], fc T h [T], fc D p [L/T], est S u, max [L], est S wp [L], est p [-], est K p [T], est Supporting mechanism groundwater flow groundwater flow infiltration excess flow (during high intensity rainfall) parameters K w [T], est K h [T], est F max [L/T], est T p [T], est

27 Ways forward Classification of catchments into sub-systems based on topography, geology, ecology, landuse Developing simple lumped conceptual subsystem models (as simple as possible) Combining these in parallel (or possibly in series) Feed these sub-models with spatially distributed rainfall Space for Time exchange

28 Conclusion There is a definite need for more knowledge on how the system behaves, both under normal and under extreme conditions There is a need to cooperate in the development of adequate tools There is a need to share operational knowledge, information and experiences h.h.g.savenije@tudelft.nl

Flash Flood Science. Chapter 2. What Is in This Chapter? Flash Flood Processes

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