Relationships between physical‐geochemical soil properties and erodibility of streambanks among different physiographic provinces of Tennessee, USA

Abstract

Erosion of cohesive soils in fluvial environments is dependent on physical, geochemical and biological properties, which govern inter‐particle attraction forces and control detachment rates from stream beds and banks. Most erosion rate models are based on the excess shear stress equation where the soil erodibility coefficient (kd) is multiplied by the difference between the boundary hydraulic shear stress (τb) and the soil critical shear stress (τc). Both kd and τc are a function of soil properties and must be obtained through in situ field or laboratory testing. Many studies have generated predictive relationships for kd and τc derived from various soil properties. These studies typically were conducted in watersheds within a single physiographic region with a common surficial geology and/or investigated a limited number of soil properties, particularly geochemical properties. With widely reported differences in relationships between τc and soil properties, this study investigated differences in predictive relationships for τc among different physiographic provinces in Tennessee, USA. Erodibility parameters were determined in the field using a mini‐jet test device. Among these provinces, statistically four unique clusters were identified from a dataset of 128 observations and these data clusters were used to develop predictive models for τc to identify dominant properties governing erosion. In these clusters, 16 significant physical and geochemical soil properties were identified for τc prediction. Among these soil properties, water content and passing #200 sieve (percentage soil less than 75 μm) were the dominant controlling parameters to predict τc in addition to clay percentage (< 2 μm), bulk density, and soil pore water chemistry. This study suggests that unique relationships exist for physiographic provinces that are likely due to soil physical‐geochemical processes associated with surficial geology that determine minerology of the cohesive soil. Copyright © 2017 John Wiley & Sons, Ltd.

Estimating Erodibility Parameters for Streambanks with Cohesive Soils Using the Mini Jet Test Device: A Comparison of Field and Computational Methods

“…Soil cohesion ranged from 8.55 kPa to 107.90 kPa. Details of other physical and geochemical properties of these soil samples were summarized in Mahalder et al [16]. The relationship between τ c and k d from the MPS-BM for the jet device dataset among the 21 Tennessee sites showed an inverse power relationship ( Figure 6).…”

“…In the first field operation, the MPS approach was used at 21 sites across Tennessee from July 2014 through August 2015. The rationale for site selection was to obtain data across multiple physiographic regions [16], in which geographical details of these study sites are described below in Section 3.2. The second operation consisted of collecting scour hole depth measurements for a single pressure setting (SPS), and at the same site location collecting scour hole depth measurements using an alternative MPS approach.…”

“…The majority of the sites were from the western part of Tennessee, which has predominantly cohesive (silt/clay) type materials. Mahalder et al [16] have described the soil properties of each site in detail.…”

“…Test locations were visually selected so that The field operation that used the MPS procedure for 21 sites was conducted across the state of Tennessee in four physiographic provinces: Valley and Ridge, Central Basin, West Highland Rim, and Coastal Plain, each with diverse geological settings with different dominant soil properties that govern estimates for the erodibility parameters [16]. Among these regions, five stream sites were located in the Valley and Ridge Physiographic Province, three sites in the West Highland Rim and the Central Basin, and 13 sites in the West Tennessee Plain and West Tennessee Uplands, sub-regions of the Coastal Plain physiographic province (Figure 1).…”

Assessing Dispersivity and Expansivity of Clay Soils in the South-East of Yazd with Aim of Investigating Correlation between Them

“…In this regards, during past decades, many researchers studied identification methods of dispersivity of soils using chemical or physical properties of soils (e.g. [3][4][5][6][7][8][9]). Among the common tests to identify dispersivity of soils are soil dispersion test (in jar), pinhole test, double hydrometer test, and chemical tests [10].…”