Critical topographic threshold of gully erosion in Yuanmou Dry-hot Valley in Southwestern China

Abstract

Gully initiation has been a subject of much discussion in the field of gully erosion. Gully initiation could be examined by the S-A relationship (S = aA Àb ) between the critical slope of the gully head (S) and the upstream drainage area (A). Gully erosion plays an important role in sediment yield and land degradation in the Dry-hot Valley region of Southwest China; however, little research has focused on gully development in this region. This study investigated gully morphology and the critical topographic threshold of permanent gullies in Yuanmou Dry-hot Valley. Data for 36 gully heads were derived from the gully digital elevation model created by high-precision real-time kinematic GPS (RTK GPS). A significant relationship between gully length and volume (r 2 = 0.77, p < 0.01) was found to exist, indicating that gully length can be used to estimate the gully erosion rate. Additionally, as vegetation coverage inside the gully increases, the gully morphology tends to be stable. The S-A relationship was S = 0.5195A À0.0899 , while AS 2 values ranged between 4.2 and 758.5 m 2 . The low value of constant b (0.0899) indicates that collapse of the gully wall is the dominant process of gully erosion in Yuanmou Dry-hot Valley.

Influence of bare soil and cultivated land use types upstream of a bank gully on soil erosion rates and energy consumption for different gully erosion zones in the dry-hot valley region, Southwest China

“…Gully erosion accounts for much of the total soil erosion that takes place, having a gully density between 3 and 5 km km -2 Zhong 2000). Although gully catchment areas are relatively small, bank gullies rapidly retreat through headcut migration and gully headwall collapse due to breaches in small topographic thresholds instigated by gully initiation as well as the distinctive lithology of the environment (i.e., a mix of fluvial and lacustrine layers in a sedimentary sequence; Dong et al 2013). In other words, channel head extension does not generally depend solely on the available catchment area itself.…”

“…Similarly, Oostwoud described that recent changes to a particular land use type involving land extension of almond cultivation appeared to have intensified bank gully head activity. In China, field investigations related to critical topographic thresholds and bank gully landform evolution under different land use types have also been conducted (Dong et al 2013;Wu and Cheng 2005;Zhu 2012). However, few bank gully erosion simulations have been developed given that erosion processes and boundary conditions are difficult to model.…”

Spatial distribution and morphologic characteristics of gullies in the Black Soil Region of Northeast China: Hebei watershed

“…It has been reported in a variety of climate zones, such as humid zone (Vanwalleghem, Poesen, Nachtergaele, & Verstraeten, 2005;Wilson, Shields, Bingner, Reid-Rhoades, & DiCarlo, 2008), semi-humid zone (Wu et al, 2008;Zucca, Canu, & Della Peruta, 2006), semi-arid zone (Bouchnak, Felfoul, Boussema, & Snane, 2009;Muñoz-Robles et al, 2010;Wilkinson, Hancock, Bartley, Hawdon, & Keen, 2013) and arid zone (Samani et al, 2009). Gully erosion was also reported in both croplands (Achten et al, 2008;Vanwalleghem et al, 2005;Wu & Cheng, 2005) and non-croplands (Dong et al, 2013;Katz, Daniels, & Ryan, 2014;Vandekerckhove et al, 2000;Zucca et al, 2006). Gullies have been found in a variety of regions in China, such as the Loess Plateau region in the northwest (Wu & Cheng, 2005), the Red Soil region in the south (Dong et al, 2013), and the Black Soil Region (BSR) in the northeast (Wu et al, 2008).…”

“…Gully erosion was also reported in both croplands (Achten et al, 2008;Vanwalleghem et al, 2005;Wu & Cheng, 2005) and non-croplands (Dong et al, 2013;Katz, Daniels, & Ryan, 2014;Vandekerckhove et al, 2000;Zucca et al, 2006). Gullies have been found in a variety of regions in China, such as the Loess Plateau region in the northwest (Wu & Cheng, 2005), the Red Soil region in the south (Dong et al, 2013), and the Black Soil Region (BSR) in the northeast (Wu et al, 2008).…”

“…Therefore, other characteristics, which are relatively easier to derive, are often used as predictors. Among them, gully length is the most frequently used, typically in the form of V = a*L b , where V is the gully volume (m 3 ), L is the gully length (m), a and b are coefficients (Dong et al, 2013;Frankl et al, 2013;KompaniZare, Soufi, Hamzehzarghani, & Dehghani, 2011;Muñoz-Robles et al, 2010;Zucca et al, 2006). The equations established in this study (Equations (3-5); Figure 5) were:…”