Abstract
Gullies are significant contributors of sediment to streams in the southeastern USA. This study investigated gully erosion in the clay-rich soils of east Tennessee under a humid subtropical climate. The aims of this study were to (1) estimate long-term erosion rates for different gully geomorphic settings, (2) compare patterns of erosion for the different settings, and (3) model the response of gully erosion to freeze-thaw events. Erosion was measured weekly from June 2012 to August 2018 using 105 erosion pins distributed in gully channels, interfluves, and sidewalls. Erosion rates were estimated from average slopes of lines of best fit of pin lengths versus time. Maximum and minimum temperature was calculated daily using an on-site weather station and freeze-thaw events were identified. Gully erosion was modeled using antecedent freeze-thaw activity for the three geomorphic settings. Long-term erosion rates in channels, interfluves, and sidewalls were 2.5 mm/year, 20 mm/year, and 21 mm/year, respectively; however, week-by-week erosion was statistically different between the three settings, indicating different erosive drivers. Models of erosion with lagged freeze-thaw variables explained up to 34.8% of the variability in erosion variables; sidewall erosion was most highly related to freeze-thaw activity. Freeze-thaw in prior weeks was an important variable in all erosion models.
Highlights
Soil detachment and removal by gully erosion is a serious form of land degradation, threatening the global environment, including arable land and water resources
Models of erosion with lagged freeze-thaw variables explained up to 34.8% of the variability in erosion variables; sidewall erosion was most highly related to freeze-thaw activity
In higher latitude and altitude areas, snowmelt runoff and freeze-thaw cycles contribute to gully erosion [14,15,16]
Summary
Soil detachment and removal by gully erosion is a serious form of land degradation, threatening the global environment, including arable land and water resources. The eroded soil is often deposited in water bodies, which increases turbidity, disturbing aquatic ecosystems and polluting drinking water supplies [3,4]. To prevent these negative impacts and to remediate affected areas, several researchers have focused on assessments of the causative factors of gully erosion, such as rainfall, snowmelt, wind, freeze–thaw cycles, gravity, and land use management [5,6]. Improper land use management is commonly the main driver of development and proliferation of gully erosion [7,8] followed by excess rainfall induced runoff on land surfaces [1]. Winter weather, snow accumulation, snowmelt, and soil freeze–thaw cycles have been used to model soil erosion [16,17], revealing that land degradation from snow melt erosion can often exceed rainfall induced erosion [18]
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