comparison of rainfall energy and soil erosion parameters from a rainfall simulator and natural rain
The effect of rainfall event sequencing on...
Transcript of The effect of rainfall event sequencing on...
The effect of rainfall event sequencing on erosion
Jantiene EM BaartmanAJAM Temme, A Veldkamp, VG Jetten, JM Schoorl
Introduction & Objective
Extreme rainfall events contribute disproportionally to total erosion The timing of these events seems to be of importance Climate change predictions (Mediterranean)
● Less total rainfall; but● More intense events
Evaluate the effect of rainfall sequencing on long-term (centennial) erosion
Methods
Methods: LAPSUS landscape evolution model
● Long-term redistribution of sediment
Study area: Prado, SE Spain• ~50 km2
• 435 – 1150 m.a.s.l.• Semi-arid: 250-530 mm/y• High inter-annual variation
Methods
Rainfall data: 1997 – 2006; 9-yr record Repeated 11x to get a 99-yr rainfall timeseries Vary the order of occurrence of rainfall:
• 1997-2006 record repeated 11x• Order of years changed randomly, keeping total rainfall and
frequency the same (50 simulations)• Minimum scenario: 11x lowest year; 11x one-but-lowest year; etc• Maximum scenario: 11x highest year; 11x one-but-highest year; etc
Note: total P is equal in all runs!
Results & Discussion
Event sequencing: no linear relation between (high or low) rainfall and (high or low) net erosion
Results & Discussion
Event sequencing: no linear relation between (high or low) rainfall and (high or low) net erosion
Conclusions & Outlook
Non-linear behaviour is evident: ● Non-varying, average annual rainfall as input results
in peaks in simulated net erosion ● Variability in rainfall as input does not necessarily lead
to a corresponding peak in simulated erosion and peaks occur at points in time when no rainfall peak occurs.
What is the cause of this non-linear behaviour?● Change in connectivity?● Next step: analyse the spatial dynamics
Thank you!
Based on:Baartman et al., 2013. Exploring the role of rainfall variability and extreme events in long-term landscape development. Catena 109: 25-38.
Input: effective rainfall
Peff = P that becomes overland flow Determined based on LISEM simulated hydrographs and
Q/P ratios
More extreme events
Inclusion of more extreme events• 10x erosivity of the most extreme event of the 1997-2006 record• Different frequencies of occurrence of such extreme event