Planar morphology and controlling factors of the gullies in the Yuanmou Dry-hot Valley based on field investigation

Abstract

The plane form of a gully can provide a basis for evaluating the gully volume and erosion rate, acting process, and evolutionary stage. For describing the planar characteristics of a permanent gully and understanding their controlling factors, this study, utilizing a total station and GPS RTK, measured the shoulder lines and channel curves of 112 gullies in six sites of the Yuanmou Dry-hot Valley and then mapped them by ArcGIS software and calculated nine parameters. The results showed that the channel lengths range from 10.88 to 249.11 m; the widths range from 6.20 to 40.99 m; the perimeters range from 54.11 to 541.67 m; the gully areas range from 153.02 to 6,930.30 m 2 ; the left-side areas range from 92.93 to 4,027.20 m 2 ; and the right-side areas range from 63.65 to 3,539.77 m 2 . The slightly sinuous and straight gullies account for 73.21% of the total gullies; the quantity of the right skewed gullies is 8.93% greater than that of the left skewed ones based on the symmetry ratio; the shape ratios range from 1.12 to 1.40 and the morphology ratios from 0.038 to 1.294; the fractal dimension is 1.192. Gullies in different sites have diverse planar characteristics. Except for the symmetry index, which was close to a negatively skewed distribution, all of the other parameters had the characteristic of positively skewed distribution. The gully area is related to the length and width, but the gully length has a weak correlation with the width. The evolutionary stage, topographic conditions, strata, soil properties, and piping erosion played very important roles in the gully planar morphology. This study could provide useful information for controlling gully erosion and safeguarding human habitation and engineering buildings.

Causes and Controlling Factors of Valley Bottom Gullies

“…Gully development depends on geomorphological [112,113] and hydrological [6,7] parameters (Table 1). Since these hydrological and geomorphological parameters vary between hillslope and valley bottomlands [36], the type of rehabilitation measures that are likely to be effective will also vary.…”

Soil Macropore and Hydraulic Conductivity Dynamics of Different Land Uses in the Dry–Hot Valley Region of China

“…The dry-hot valley region of Southwest China is characterized by hot weather with distinct wet and dry seasons [22]. The uneven distribution of annual rainfall in this region leads to different soil water responses.…”

Effect of Sampling Spacing on the Accuracy of Volume of a Medium-Size Gully

“…Accurate morphological parameters of a gully are important, not only for quantifying soil losses and the rate of gully erosion, but also for understanding their complex dynamics (Castillo et al, 2018;Deng et al, 2015a;Deng et al, 2015b;Nachtergaele and Poesen, 1999;Poesen et al, 2003). Based on cross-sectional morphology, gullies have commonly been recognized as V-shaped and U-shaped according to the cross sections (Deng et al, 2015b).…”

“…Diverse techniques are used to determine gully erosion in field studies (Castillo et al, 2012). The parameters of a gully can be measured either directly or indirectly in the field using instruments, i.e., metric ruler (Bruno et al, 2008), pole (Castillo et al, 2012), tape meter (Frankl et al, 2015), micro-topographic profiler (Avanzi et al, 2018), total station (Caraballo-Arias et al, 2016; Deng et al, 2015a), GPS RTK (Deng et al, 2015a;He et al, 2005), and laser profilemeter (Castillo et al, 2012). In recent years, new technologies such as Unmanned Aerial Vehicles (UAV) (Bazzoffi, 2015;Stocker et al, 2015), structure-from-motion (SFM) (Christian and Davis, 2016), stereoscopic images (Nachtergaele and Poesen, 1999), 3D photo-reconstruction (Gomez-Gutierrez et al, 2014), terrestrial laser scanning (TLS) (Taylor et al, 2018) and light detection and ranging (LiDAR) (Taylor et al, 2018;Wells et al, 2017) have been successfully applied in gully morphology.…”