Abstract. To explore the sensitivity of rivers to blocking from landslidedebris, we exploit two similar geomorphic settings in California'sFranciscan mélange where slow-moving landslides, often referred to asearthflows, impinge on river channels with drainage areas that differ by afactor of 30. Analysis of valley widths and river long profiles over∼19 km of Alameda Creek (185 km2 drainage area) andArroyo Hondo (200 km2 drainage area) in central California shows avery consistent picture in which earthflows that intersect these channelsforce tens of meters of gravel aggradation for kilometers upstream, leadingto apparently long-lived sediment storage and channel burial at these sites.In contrast, over a ∼30 km section of the Eel River (5547 km2 drainage area), there are no knickpoints or aggradation upstreamof locations where earthflows impinge on its channel. Hydraulic andhydrologic data from United States Geological Survey (USGS) gages on Arroyo Hondo and the Eel River, combinedwith measured size distributions of boulders input by landslides for bothlocations, suggest that landslide derived boulders are not mobile at eithersite during the largest floods (>2-year recurrence) with field-measured flow depths. We therefore argue that boulder transport capacity isan unlikely explanation for the observed difference in sensitivity tolandslide inputs. At the same time, we find that earthflow fluxes per unitchannel width are nearlymore »
A new method to detect changes in displacement rates of slow-moving landslides using InSAR time series
Slow-moving landslides move downslope at velocities that range from mm year−1to m year−1. Such deformations can be measured using satellite-based synthetic aperture radar interferometry (InSAR). We developed a new method to systematically detect and quantify accelerations and decelerations of slowly deforming areas using InSAR displacement time series. The displacement time series are filtered using an outlier detector and subsequently piecewise linear functions are fitted to identify changes in the displacement rate (i.e., accelerations or decelerations). Grouped accelerations and decelerations are inventoried as indicators of potential unstable areas. We tested and refined our new method using a high-quality dataset from the Mud Creek landslide, CA, USA. Our method detects accelerations and decelerations that coincide with those previously detected by manual examination. Second, we tested our method in the region around the Mazar dam and reservoir in Southeast Ecuador, where the time series data were of considerably lower quality. We detected accelerations and decelerations occurring during the entire study period near and upslope of the reservoir. Application of our method results in a wealth of information on the dynamics of the surface displacement of hillslopes and provides an objective way to identify changes in displacement rates. The displacement rates, their spatial more »
- Publication Date:
- NSF-PAR ID:
- 10369335
- Journal Name:
- Landslides
- Volume:
- 19
- Issue:
- 9
- Page Range or eLocation-ID:
- p. 2233-2247
- ISSN:
- 1612-510X
- Publisher:
- Springer Science + Business Media
- Sponsoring Org:
- National Science Foundation
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