University of Twente Student Theses
Hydrological and hydraulic analysis of post seismic Hongchun debris flow, Sichuan province, China
Adegbe, Mamodu (2012) Hydrological and hydraulic analysis of post seismic Hongchun debris flow, Sichuan province, China.
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| Abstract: | In many parts of the world debris flows are one of the most dangerous of all mass wasting events. Mountainous areas with high slope instability, high seismic activities and extreme rainfall condition are the main triggering factors (Huang & Li, 2008). The Monday, May 12, 2008, mega-earthquake of magnitude 8.0 that struck the Wenchuan area, Northwestern Sichuan province in China was catastrophic Tang et al (2011)and led to Landslides and subsequent Debris flow in Hongchun catchment which has an area of 5.35 km2 and a channel length of 3.55 km. The main objectives of this research is to understand the hydrological and hydraulic analysis of the post seismic Hongchun debris flow, inventorize the landslides as the potential source of debris in the catchment, estimated the volume of debris in the catchment based on field observation and attempt the reconstruction of the August 14th, 2010 debris flow event in the Hongchun catchment. LISEM was used to model the rainfall-runoff relationship of the catchment and the infiltration patterns. The total Volume, area extent, velocity, depth, specific energy and impact force of the debris flow were obtained using the FLO-2D model. LISEM simulated one runoff scenario on a whole catchment hydrograph with three peaks corresponding to high discharge but produce very little runoff. The interception (2mm) and infiltration (0n the average was 120mm) were not high.The model reveals almost a uniform infiltration pattern for the catchment. This might be due to the uniform texture and geology of the catchment. The study found through the intensive field geomorphological mapping of the landslides (inventory), field observation and historical knowledge (through interviews) that the co-seismic landslides are the potential source of debris flows in the Hongchun catchment. 41 landslides were mapped in the catchment and characterized according to their parts (scarp or body), age, and degree of activity and the estimates of their volume were made to 1,675,000 m3. The 2010, event initiated in two different areas and the FLO-2D modeling were chosen from this two main initiation zone based on susceptibility assessed from Geomorhological field mapping and Tang (2011). 40.3% of the August 14, 2010 debris flow event was reconstructed using FLO-2D model in a manner consistent within the limit of the data available and limit of the researcher expertise with the FLO-2D model. In addition, the model was calibrated (161,350 m3) using a back analysis of the debris flow event of 2010. Finally, given the available tools, LISEM, FLO-2D, geomorphological mapping, field observation, interviews and data, 40.3% of the debris flow event of 14th August, 2010 was reconstructed. These results are however, preliminary and are guide for future research. |
| Item Type: | Essay (Master) |
| Faculty: | ITC: Faculty of Geo-information Science and Earth Observation |
| Programme: | Geoinformation Science and Earth Observation MSc (75014) |
| Link to this item: | https://purl.utwente.nl/essays/93417 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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