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Enhancing model realism by incorporating landscape characteristics: Topography driven rainfall runoff modeling (FLEX-TOPO) IAHS 2013, 23 th of July 2013.

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Presentation on theme: "Enhancing model realism by incorporating landscape characteristics: Topography driven rainfall runoff modeling (FLEX-TOPO) IAHS 2013, 23 th of July 2013."— Presentation transcript:

1 Enhancing model realism by incorporating landscape characteristics: Topography driven rainfall runoff modeling (FLEX-TOPO) IAHS 2013, 23 th of July 2013 By:Shervan Gharari Markus Hrachowitz Fabrizio Fenicia Hongkai Gao Tanja Euser and Hubert Savenije

2 Hunting the Hydrological Snark Questions… How to see the hydrological Snark…? How far is the hydrological Snark…? How big is the hydrological Snark…? How does the hydrological Snark look like…? (Andreassian et al., 2009)

3 The Hydrological Snark & Questions… Are we in love with the hydrological Snark? Or… Are we in love with the instruments used to find the hydrological Snark?

4 What are the objectives… To apply the lessons learned from case specific studies and to be able to incorporate our expert knowledge into modeling. [Savenije (2009)] To use topography and HRUs in model development. To get the most out of the least knowledge available.

5 Wetland Hillslope Plateua Gharari et al., (2011) HESS

6 Landscape classes for this case study are: -Wetland: water table close to the surface, saturation overland flow -Hillslope: steep slopes, shallow rapid subsurface flow -Plateau: modest slope, deep percolation Assigning dominant runoff processes to each landscape and develop the model structures accordingly.

7 PI T RCRC RPRP RuRu RfRf QfQf RsRs FLEX A QsQs Lumped FLEX B PI T RCRC RPRP RuRu RfRf Q fw PI T RPRP RuRu RfRf Q fr RsRs QsQs Remainder (85%) Wetland (15%)

8 Although complex … Parameter constraints: -Hillslope are mostly forested  Imaxh> Imaxw & Imaxh>Imaxp -Hillslope has longer lag time compare to wetland  Lagw< Lagh -Plateau has a deeper unsaturated zone compared to wetland and hillslope  Sumaxp>Sumaxh & Sumaxp>Sumaxw

9 Although complex … Process-based constraints: -Peak flows during a dry period are mostly generated by the wetland  Qfw,dry/Qfh,dry>1 -Peak flows during a wet period are mostly generated by the hillslope  Qfw,wet/Qfh,wet<1 -Annual runoff coefficient  0.2<(Q/P) & (Q/P)<0.45 (Budyko)

10 Then how to parameterize?! Parameter space Satisfies 1 or more constraints Satisfies N or more constraints! (All) Satisfies 2 or more constraints Satisfies N-1 or more constraints Parameter space which satisfies all the constraints but is not optimal calibrated on observed hydrograph Un-calibrated but constrained

11 NS = -0.87 NS = 0.64 NS = 0.71 Un-calibrated but constrained

12 Parameter space Satisfies 1 or more constraints Satisfies N or more constraints! (All) Satisfies 2 or more constraints Satisfies N-1 or more constraints Un-calibrated but constrained Calibrated and constrained Then how to parameterize?! Pareto optimal

13 Calibrated and constrained NS = 0.91 NS = 0.87 NS = 0.88

14 Validated for calibrated and constrained NS = 0.75 NS = 0.80

15 Comparison & conclusion & discussion!

16 FLEX-TOPO case study in Heihe, China

17 But answering my research questions! Answers… To be honest! I don’t know... But the hydrological Snark might not be that “far away” or that “close”… It might not be that “big” or that “small”… It might not be that “ugly” or that “beautiful”… These are just my feelings! Questions… How to see the hydrological Snark…? How far is the hydrological Snark…? How big is the hydrological Snark…? How does the hydrological Snark look like…? The revelations of Devout and Learn’d Who rose before us, and as Prophet burn’d Omar Khayyám, 11th c. transl.: Edward FitzGerald, 19th c. Are all but Stories, which, awoke from Sleep They told their comrades and to sleep return’d

18 But answering my research questions! Answer… Seems dangerous to answer! Questions… Are we in love with the hydrological Snark? Or… Are we in love with the instruments we use to find the hydrological Snark? The revelations of Devout and Learn’d Who rose before us, and as Prophet burn’d Omar Khayyám, 11th c. transl.: Edward FitzGerald, 19th c. Are all but Stories, which, awoke from Sleep They told their comrades and to sleep return’d

19 Thank you for Your Attention


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