Spatial interaction between collapsed pipes and landslides in hilly regions with loess-derived soils.

While most studies focuses on the effect of soil pipes on hillslope stability, this study investigates the impact of landsliding on pipe development. It is hypothesized that poorly drained landslides change the hillslope hydrology through (i) surface flow obstruction, by changing topography, as well as (ii) subsurface flow obstruction by tilting less-permeable clay-rich substrates. Hence, new preferential flow paths are created at reverse slopes within the landslide zone and at the boundary of the landslide, enhancing pipe formation. This study aims at a better understanding of the interaction between collapsed pipe (CP) occurrence and landslide (LS) occurrence in the Flemish Ardennes (Belgium) by comparing their respective spatial patterns. At least 24.5 % of the 139 sites with CP were related to the occurrence of an observed LS. Poorly drained LS may create favourable conditions for pipe development. Outside LS, natural and anthropogenic (e.g. broken field drains, road drainage) causes may result in concentrated subsurface flow, resulting in pipe development. No evidence was found that pipe development enhanced landsliding, probably, because the subsurface drainage discharge generated upslope of the LS is too low. Even when pipes get blocked, it is more likely that new pipes develop and new collapses occur than they trigger or reactivate LS. A conceptual model is presented summarizing all elements that influence piping erosion in the Flemish Ardennes, including the role of LS.

VERACHTERT Els;  VAN DEN EECKHAUT Miet;  POESEN Jean;  DECKERS Jozef; 

2014-07-30

WILEY-BLACKWELL

JRC73077

0197-9337,   

http://onlinelibrary.wiley.com/doi/10.1002/esp.3325/abstract,    https://publications.jrc.ec.europa.eu/repository/handle/JRC73077,   

10.1002/esp.3325,