2. presentation hp

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2. presentation hp

  1. 1. Hydrologycal modeling ofboundary conditions of flash floods Peter Hegedüs University of Pécs, Hungary YWP 2012 May 16-18, Sofia
  2. 2. Introduction• What is a flash floods?• What are the earlier cases?• Why are we dealing with kind of floods?• How can we measure boundary conditions?• What are the main goals of our study?
  3. 3. Generation of flash floods• Increasing weather extremities• Intensity of rainfall events are growing• Rapid runoff according to relief• Short concentration time
  4. 4. Earlier examples• Boscastle (UK) 2004• Rapid City (South-Dakota, USA) 1972• Mátrakeresztes (Hungary, 2005) Economic & Infrastructural damages Private property losses Life losses
  5. 5. Major property damages• ~140m3/s peak discharge• 100 houses damaged Boscastle (UK)
  6. 6. Rapid city: dam breach
  7. 7. Pilot area properties Bükkösd Stream’s watershed in SW Hungary• Small low-mountainous & hilly region• Quite high relief• 7 major flood events from the earlier decades• Relatively representative area (1.7 km 2 )
  8. 8. Measurement instruments • Rain gauges with EM-50 loggers (Decagon Devices Inc.) • 5-TM TDR-type soil moisture sensors • Stream gaugeshttp://ttk.pte.hu/kornyezettudomany/baross/galeria_kepek/decagon.JPG
  9. 9. Gauges indicated on orthophotos
  10. 10. Data analysis• HEC-HMS 3.4 hydrologic modeling program (Davis, USA)• Arc GIS 9.2• AGROTOPO soil database• CLC land cover
  11. 11. Results• Precipitation is crucial, however soil properties are very important• Time of concentration is also considerable• Flood occurance in late spring, summer
  12. 12. Soil moisture• Monthly averages (May, June) usually between 12.1 – 19.8 % (VWC)• Major differences
  13. 13. Time of concentration• Peak discharge & precipitation values needed• Intensity can be variable between a short range of area• More rapid concentration on tributary streams
  14. 14. Simulation of the flood event in 2010 May• Numerous data needed: water content, canopy cover, stream discharge etc.• Western and eastern watershed differences
  15. 15. Conclusions• HEC-HMS is suitable for modeling• Plethora of data – consideration of boundary condition analysis is necessary• Rainfall intensity greatly varies – secondary effect problems• VWC & soil saturation calculation must be cautious – software sensibility
  16. 16. AcknowledgementThe present study was funded by the “TÁMOP 4.2.1.B-10/2/KONV-2010-0002” Scolarship (Developing competitiveness of universities in the South Transdanubian Region)
  17. 17. Thank you for your attention!

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