Critical shear stress and critical flow rates for initiation of rilling

Abstract

Critical sh(川r stress and critical flow rates for initiation of rillin日 .r Hydrol ' 142: 251-271 This study was conducted to identify critical shear stress and critical flow rates re叶uired to initiate rilling on 比lected sites. The data used in this investigation were collected from soils located throughout the US 八 认 h e re crop residues had oeen removed 、and moldooard plowing 且nιI disking had occurred. RunolLlIld 出 ， i! l(1sS measurements were made on sites where simulated rainfall was applied to pre! 川med rills. Multiple rcgrcs川on analyses were used to relate critical shear stress values and critical Il o 认 仁l t e s to selected 刊oil properties , The s(丁il-oased regression equations were found to provide reli 川、 Ie estimates. Informati 川1 identilied in this study will improve our aoility to understand and pr仆perly model upl 川ld runolr and erosion processes Several equations for estimating bed load sediment transport have been

Critical Conditions for Rill Initiation

“…Despite differences in soil type, plot size, and methodologies, the critical shear stress values obtained in this study were either within the range of that of the other reports, or in the same order of magnitude. For example, Laflen et al (1991) studied 56 soil types and reported a shear stress range from 0.00 to 6.64 Pa. Gilley et al (1993) studied 30 soil types and used the same data set as Laflen et al (1991) but a different calculation method and obtained a shear stress range from 1.73 to 10.60 Pa. These values were consistent with the results of this study (1.33 to 2.63 Pa).…”

“…The steepness of the plots in the studies of Laflen et al (1991) and Gilley et al (1993) were only 6.10% and 5.57%, respectively. The values of critical shear in table 2 for the 8.75% plot slope ranged from 2.54 to 2.63 Pa, similar to the values found by Laflen et al (1991) and Gilley et al (1993). This decrease in critical shear with slope is different from the results of Elliot et al (1990), who found that soil formed on steeper slopes tended to exhibit higher critical shear values.…”

“…Laflen et al (1991) calculated the critical shear values on these soils to be 3.05 and 3.11 Pa, respectively. Using a different method of analysis, Gilley et al (1993) determined that the soil shear stress values for the two soils were 3.58 and 4.30 Pa, respectively. The steepness of the plots in the studies of Laflen et al (1991) and Gilley et al (1993) were only 6.10% and 5.57%, respectively.…”

“…Using a different method of analysis, Gilley et al (1993) determined that the soil shear stress values for the two soils were 3.58 and 4.30 Pa, respectively. The steepness of the plots in the studies of Laflen et al (1991) and Gilley et al (1993) were only 6.10% and 5.57%, respectively. The values of critical shear in table 2 for the 8.75% plot slope ranged from 2.54 to 2.63 Pa, similar to the values found by Laflen et al (1991) and Gilley et al (1993).…”

La morphogenèse accélérée menace-t-elle les régions rurales de l’ouest du bassin parisien ?

“…L'incision du sol se produit quand la force tractrice du ruissellement dépasse une valeur critique (Birot, 1981 ;Govers, 1991 ;Gilley et al, 1993) qui varie selon la résistance du sol (Quansah, 1985 ;Le Bissonnais et al, 1993). Si la vitesse ne dépasse que de peu la valeur critique, qu'on peut évaluer d'après la courbe de Hjulström (1935) à 20 cm/s pour les sols à texture sableuse, le ruissellement concentré ne creuse que des griffes et des rigoles.…”