the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 29 May 2026
Evolution of the Unsaturated Permeability and Internal Erosion Characteristics of Ili loess under Rainfall
Abstract. The evolution of microcharacteristics of the loess affected by the combination of the permeability and seepage erosion significantly affect the integrity and the stability of the loess slopes. To investigate the in-behind mechanics of the loess under the rainfall, the self-designed experimental framwork was adopted to carry out the laboratory, during which the scanning electron microscope (SEM) tests, laser particle size analysis, as well as the numerical simulation analysis were conducted in parallel.The experimental results showed that the unsaturated permeability of the loess exponentially increases with the increased water content. The migration of clay particles alters the microstructure of the soil, resulting the enhancement of the porosity and permeability, associated with a significant clay particles loss within the shallow layer. These loess accumulated in the deep layer transformed into a lubricating water film layer with strong lubricity, which reduces the overall stability of loess slopes. Furthermore, the changed permeability results from the conversion between micropores, small pores, mespores, and macropores. Because that the internal erosion forms a layer of clay particle aggregation at a certain depth, the formation of slip surfaces of landslides was further promoted. The research is of great significantance, which makes contribute to the in-depth understanding about the mechanism of rainfall impact on the microstructure and unsaturated permeability characteristics of the loess.
- Preprint
(6946 KB) - Metadata XML
- BibTeX
- EndNote
Interactive discussion
Status: closed
- RC1: 'Comment on egusphere-2026-1999', Anonymous Referee #1, 14 Sep 2026
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2026-1999', Anonymous Referee #1, 14 Sep 2026
This manuscript combines rainfall infiltration tests under three rainfall intensities, unsaturated permeability calculations, SEM, laser particle size analysis, and COMSOL simulations to study internal erosion, clay-particle migration, and the evolution of microstructure and unsaturated permeability in Ili loess. The topic is overall interesting, and the multi-method approach is a clear strength. However, several issues need to be improved before possible publication in NHESS. Specific comments are as below.
1. Lines 1–3, 7–13, Page 1 and other pages: The title, abstract, and maintexts overgeneralize from Ili loess to “loess.” Restrict claims to Ili silty loess unless broader evidence is provided. Or consider provide more details of differences from Ili loess and loess.
2. Page 5, 2.2.1 Experimental Method: The rigid acrylic permeameter cannot capture volume changes during saturation, and sidewall preferential flow, grass cover, and boundary effects are not quantified. So I suggest add an in-depth discussion on it.
3. Table 1, Page 5 and Lines 135–141, Page 6: There is a serious inconsistency between the “natural” moisture content/density in Table 1 (6.41%, 1.43 g/cm³) and the prepared values (14.1%, 1.65 g/cm³). Please clarify natural vs. remolded/compacted states and correct all related descriptions.
4. Page 10, Table 2; Page 17, lines 411–435: Key numerical parameters, e.g., critical seepage velocity 1.5E-16 m/s and erodible fine-particle density 400 kg/m³, lack clear calibration/sources. How do authors validate the model against measured K(θ), water content, and clay-loss profiles?
5. The permeability and seepage-erosion results rely solely on 1-D lab columns and COMSOL simulations, so how do authors consider the uncertainty of permeability (or seepage field) between field-scale monitoring and lab tests, e.g.: https://doi.org/10.1029/2022GL098211. The authors should quantify repeatability errors in the calculated permeability and discuss how field monitoring could validate the inferred clay migration and slip-surface mechanism.
6. Line 566, Pages 22: “TThree” should be a typo.
7. Generalization to Chinese loess and early warning is premature based on one Ili silty loess site. Authors should define applicability limits and discuss differences from Loess Plateau loess, scale effects, vegetation, evaporation, and freeze-thaw.Citation: https://doi.org/10.5194/egusphere-2026-1999-RC1
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 110 | 74 | 23 | 207 | 20 | 20 |
- HTML: 110
- PDF: 74
- XML: 23
- Total: 207
- BibTeX: 20
- EndNote: 20
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
This manuscript combines rainfall infiltration tests under three rainfall intensities, unsaturated permeability calculations, SEM, laser particle size analysis, and COMSOL simulations to study internal erosion, clay-particle migration, and the evolution of microstructure and unsaturated permeability in Ili loess. The topic is overall interesting, and the multi-method approach is a clear strength. However, several issues need to be improved before possible publication in NHESS. Specific comments are as below.
1. Lines 1–3, 7–13, Page 1 and other pages: The title, abstract, and maintexts overgeneralize from Ili loess to “loess.” Restrict claims to Ili silty loess unless broader evidence is provided. Or consider provide more details of differences from Ili loess and loess.
2. Page 5, 2.2.1 Experimental Method: The rigid acrylic permeameter cannot capture volume changes during saturation, and sidewall preferential flow, grass cover, and boundary effects are not quantified. So I suggest add an in-depth discussion on it.
3. Table 1, Page 5 and Lines 135–141, Page 6: There is a serious inconsistency between the “natural” moisture content/density in Table 1 (6.41%, 1.43 g/cm³) and the prepared values (14.1%, 1.65 g/cm³). Please clarify natural vs. remolded/compacted states and correct all related descriptions.
4. Page 10, Table 2; Page 17, lines 411–435: Key numerical parameters, e.g., critical seepage velocity 1.5E-16 m/s and erodible fine-particle density 400 kg/m³, lack clear calibration/sources. How do authors validate the model against measured K(θ), water content, and clay-loss profiles?
5. The permeability and seepage-erosion results rely solely on 1-D lab columns and COMSOL simulations, so how do authors consider the uncertainty of permeability (or seepage field) between field-scale monitoring and lab tests, e.g.: https://doi.org/10.1029/2022GL098211. The authors should quantify repeatability errors in the calculated permeability and discuss how field monitoring could validate the inferred clay migration and slip-surface mechanism.
6. Line 566, Pages 22: “TThree” should be a typo.
7. Generalization to Chinese loess and early warning is premature based on one Ili silty loess site. Authors should define applicability limits and discuss differences from Loess Plateau loess, scale effects, vegetation, evaporation, and freeze-thaw.