Grain-Size Analysis of Debris Flow Alluvial Fans in Panxi Area along Jinsha River, China

Abstract

Abstract:The basic geometric parameters of 236 debris flow catchments were determined by interpreting SPOT5 remote sensing images with a resolution of 2.5 m in a 209 km section along the Jinsha River in the Panxi area, China. A total of 27 large-scale debris flow catchments were selected for detailed in situ investigation. Samples were taken from two profiles in the deposition zone for each debris flow catchment. The φ value gradation method of the grain size was used to obtain 54 histograms with abscissa in a logarithmic scale. Five types of debris flows were summarized from the outline of the histogram. Four grain size parameters were calculated: mean grain size, standard deviation, coefficient of skewness, and coefficient of kurtosis. These four values were used to evaluate the features of the histogram. The grain index that reflects the transport (kinetic) energy information of debris flows was defined to describe the characteristics of the debris-flow materials. Furthermore, a normalized grain index based on the catchment area was proposed to allow evaluation of the debris flow mobility. The characteristics of the debris-flow materials were well-described by the histogram of grain-size distribution and the normalized grain index. OPEN ACCESSSustainability 2015, 7 15220

Measuring the grain‐size distributions of mass movement deposits

“…As a result, mass movement GSDs are often generated from smaller than ideal sample sizes, without the rigorous reporting of sampling that is common in fluvial geomorphology. Attal and Lavé (2006), Bunte and Abt (2001a, b), Casagli et al (2003), Chen et al (2001), Dunning (2006), Genevois et al (2001), Hubert and Filipov (1989), Ibbeken et al (1998), Major and Voight (1986), Sosio et al (2007), Whipple and Dunne (1992), Zhang et al (2011Zhang et al ( , 2015 Pebble count and survey tape Frequency/number…”

“…The minimum grain size depends on the resolution of the image and the maximum grain Attal and Lavé (2006), Casagli et al (2003), Crosta et al (2007), Genevois et al (2001), (Continues) have been used (e.g. Attal & Lavé, 2006;Attal et al, 2015;Casagli et al, 2003;Crosta et al, 2007;Dunning, 2006;Zhang et al, 2015).…”

“…Manual photo counts involved measuring the apparent b-axis of grains using photos taken parallel to the surface (Attal & Lavé, 2006;Casagli et al, 2003;Crosta et al, 2007;Genevois et al, 2001;Ibbeken et al, 1998;Kellerhals & Bray, 1971;Zhang et al, 2011Zhang et al, , 2015. We conducted manual photo counts in all three locations by taking photos using a smartphone camera (Figure S4, image resolutions ranged from 0.12 mm pi À1 in Tredegar to 0.39 and 0.46 mm pi À1 in Liusha and Luoquan).…”

Parametric Study on Dynamic Response of FRP Masonry Structures under the Impacts of Debris Flow

“…Debris flow, usually caused by blizzards or heavy rains, is a solid-liquid, two-phase fluid, containing a large number of sand and gravel particles [1]. Mountain areas, where debris flow is generated from frequent eruptions [2], account for two-thirds of China's land area [3]. In these areas, masonry structures constitute one of the main structural forms used in inhabited areas.…”

Study on Dynamic Response of Novel Masonry Structures Impacted by Debris Flow

“…China is a mountainous country, with mountain areas accounting for about two-thirds of the land area. Debris flow erupts frequently and with high intensity in the western regions of China [4], especially after the Wenchuan earthquake, which provided a large number of unconsolidated deposits [5]. On 7 August 2010, a large-scale debris flow occurred in Zhouqu County.…”