Rainwater Infiltration Research Articles

Innovative multi-criteria risk assessment framework for unsanitary, closed landfills: Integrating the fuzzy analytic hierarchy process with a weighted geometric mean approach.

In the past, unsanitary landfills were a common method for municipal solid waste disposal in developing countries. Although many nations have closed these landfills, the environmental pollution risks and impacts persist. This study introduces a new multi-criteria risk assessment framework specifically designed for closed, unsanitary landfills. The framework focuses on 18 key indicators categorized into three groups: landfill characteristics, waste composition, and properties of leachate and landfill gas. The Analytic Hierarchy Process (AHP) was employed to determine the weighting of these criteria, providing a more accurate way to account for uncertainties and subjective judgments. The study conducted a sensitivity analysis comparing the weighted arithmetic and geometric mean aggregation methods, finding that the geometric mean is superior for synthesizing the sub-indices in land risk assessment. The framework not only assesses risk but also provides specific action recommendations tailored to different risk levels, enabling local authorities to prioritize and implement risk reduction measures effectively, even in resource-constrained settings. The application of the framework on the Trung Son landfill indicated that the majority of waste at the landfill was ordinary waste, with high moisture content, varying over time and at different depths. The leachate was rich in organic matter, and the site was in the acidification phase of biodegradation, resulting in limited methane emissions. The landfill presented a very high environmental risk, and required immediate remediation. In the absence of allocated funding and resources, it is recommended to construct a temporary final cover and runoff collection system to minimize rainwater infiltration and odor dispersion in the surrounding areas.

Conservation Problems of Wall Paintings Within the Architectural Heritage

The Armenian legislation is currently protecting and preserving architectural monuments, archaeological sites, and minors’ artistic forms of art like xač‘k‘ars. Unfortunately, there are several cases of precious wall paintings preserved inside religious buildings (Tat‘ev, Lmbatavank‘, K‘obayr, Mastarà) being damaged during architectural monument restoration. In recent years, there has been a lot of interest in study, conservation, and restoration of wall paintings in Armenian churches; however, there is one terrible reality to report: the neglect and abandonment of the protection and safeguarding of visible wall paintings for many bureaucratic and logistical reasons, as well as reasons for complete indifference for the destiny of the frescoes. A significant illustration of this negative attitude is the chapel of the Armenian monastery of K‘obayr. After many years of abandonment, the Armenian Ministry of Education, Science, Culture and Sport made a move and began a campaign of studies and restorations in collaboration with the Polytechnic of Milan, to restore the buildings and wall paintings. Restoration work on the K‘obayr chapel has been put on hold since 2013 due to inadequate administrative administration. As a result, the chapel's single nave's double-pitched roof, which is incomplete has remained exposed for the past 10 years, and rainwater infiltration formed a lovely part of the wall paintings. Our four years of endless reports and reminders have yielded nothing. The purpose of this article is to show once again, that the wall paintings in Armenian churches are historical monuments that must be safeguarded and are an inseparable key component of each existing church's monumental architectural heritage; consequently, they must be protected.

PALAEOLITHIC MAP ENGRAVED FOR STAGING WATER FLOWS IN A PARIS BASIN SHELTER

SummaryThe Ségognole 3 shelter lies within a quartzitic sandstone megaclast in a lag deposit in the Paris Basin. It displays a female sexual configuration associated with a horse engraving, stylistically attributed to the Upper Palaeolithic. Recent studies have demonstrated that modifications to the natural features of the shelter had been undertaken to cause water to flow through what is seen as the vulva. New investigations reported here describe additional modifications to natural features in the shelter to direct rainwater infiltration to a network of channels engraved onto the shelter floor to form a functioning representation of watercourses. The carved motifs and their relationship with natural features in the sandstone of the shelter can be compared with major geomorphological features in the surrounding landscape. The engraved floor is not quite a map but more like a model in miniature of the surrounding landscape, potentially a world‐first 3D‐model of a Palaeolithic territory.

Study on Soil and Water Loss on Slope Surface and Slope Stability Under Rainfall Conditions

For a binary structure slope with a soil layer on the top and a rock layer on the bottom, during the rainfall process, surface runoff will cause soil and water loss on the slope surface and damage to the slope environment. When rainwater infiltrates into the slope, the pore water pressure in the soil gradually increases, the shear strength of the soil decreases, and a weak zone is formed at the soil–rock interface, which has a significant impact on the stability of the slope. Therefore, to study the soil and water loss on the slope surface and the stability of the slope under rainfall conditions, we used theoretical analysis, indoor model tests, and numerical simulations to conduct a comprehensive exploration of this issue, and the following conclusions were formed: the pore water pressure in the shallow layer is greater than that in the deep layer, and the pore water pressure at the toe of the slope is greater than that at the top of the slope; as the slope gradient increases, the time when the pore water pressure at the toe of the slope begins to respond gradually speeds up; the slope displacement first occurs at the lower part of the slope, then in the middle, and finally at the upper part; the time when the displacement at each point on the slope surface begins to respond gradually speeds up with the increase in the slope; the damage form at a small slope gradient is mainly flow sliding, and the damage process is continuous; the damage form at a large slope gradient is mainly flow sliding and overall sliding, and the damage process is continuous and sudden; when the binary structure slope fails, the sliding surface includes the internal sliding surface of the soil and the sliding surface at the soil–rock interface, but when the slope gradient is small, the relative sliding at the soil–rock interface is small, and a continuous sliding surface cannot be formed; and when the slope gradients are small (30° and 40°), the displacement decreases continuously from top to bottom, and no overall sliding surface is formed. The larger values of plastic strain mainly occur in the upper and middle parts of the slope, there is no formation of a continuous plastic strain zone, and the damage mode is flow sliding; when the slope gradients are large (50° and 60°), the displacement is the largest in the upper part, and a large displacement also occurs in the lower part, forming a sliding surface that penetrates through the soil–soil and rock–soil layers. The larger values of plastic strain occur in the upper, middle, and lower parts of the slope, a continuous plastic strain zone is formed, and the damage modes are flow sliding and overall sliding; numerical simulations were carried out on a typical actual slope, and consistent results were obtained.

Effects of pore water and pore air pressure on the slope failure mechanisms due to rainfall in centrifuge investigation

BackgroundThe slope failures triggered by heavy rainfall are challenging to predict. However, their severe impact and potential for extensive damage emphasize the urgent need for effective strategies to mitigate these risks. This study aimed to investigate the effects of pore water pressures (PWPs) and pore air pressures (PAPs) on slope failure during heavy rainfall under centrifuge condition. Three centrifuge rainfall model tests were conducted with varying rainfall intensities (I) and relative densities (Dr). In this experiment, the slope model was subjected to a centrifugal acceleration of 30 G.ResultsIn all cases, slope failures started at the slope toes when the PWPs became positive and phreatic surfaces appeared on the slope surface. In the Toyoura sand case, the PAPs increased slightly at the slope crest, hardly changed at the slope toe, and oscillated at the slope shoulder due to rainwater infiltration. The entire slope failure was observed in this case. In the Silica sand cases, only localized slope toe failures were observed. The PAPs slightly oscillated with small changes in the silica sand case with a relative density of Dr = 50%. However, in the case with a Dr = 25%, the PAPs at the slope toe significantly increased compared to the other parts, and the oscillations were comparatively large. After the first failure occurred at the slope toe in the silica sand case with a Dr = 25%, cracks and slip lines appeared at the slope crest.ConclusionsThe three cases illustrated the complex relationship between soil properties, rainfall intensity, and the dynamics of pore water and pore air pressure on slope stability during heavy rainfall. From the behaviour of PAPs and PWPs in all cases, it was found that the transition from air to water occurred smoothly, and the isolation of air was not observed even during heavy rainfall. Changes in PAPs were far smaller than those in PWPs, indicating a smaller impact on slope stability than PWPs.

Geodiversity Assessment of Widodaren Spring: A Treasure Trove Site for Bromo Tengger Volcano’s Future Geopark

Abstract The Bromo Tengger Volcano in Indonesia, a prominent geotourism spot, features the notable Widodaren Spring within its caldera, originating from the inactive Widodaren Vulcanic Cone. This study evaluated the geodiversity of Widodaren Spring through field and laboratory analyses and identified geodiversity elements by assessing their potential educational utility (PEU), potential touristic utility (PTU), and degradation risk (DR). Widodaren Spring is unique, showcasing rocks, hydrogeology, and landscape elements. This location is composed of pyroclastic fall deposits and pyroclastic surges, which characterize the products of volcanic activity on this volcano and provide a Sea of Sand Caldera landscape. Field and laboratory data indicate that this spring is genetically topographic-stratigraphic and hydrochemically calcium-chloride-type. The high levels of sulfate-chloride in the groundwater samples suggest the influence of volcanic gases from the nearby Bromo Volcanic Cone. Rainwater infiltration at the upper cone (2400-2560 meters) flows through lapilli layers serving as aquifers, with tuff and lapilli tuff layers below being impermeable to semi-permeable. Geodiversity assessments revealed a high educational utility potential (PEU) of 310 points, medium tourist utility potential (PTU) of 260 points, and low degradation risk (DR) of 135 points. The high PEU score was attributed to the site’s unique geological elements, making it valuable for education and science. The medium PTU score reflects its location in a national park, limiting accessibility but protecting it from human-caused damage. Potential natural damage may arise from weathering and volcanic eruptions on Mount Bromo. In conclusion, Widodaren Spring possesses significant geodiversity value with great potential for education and tourism, alongside a minimal risk of degradation. This site is a treasure trove for the future Bromo-Tengger Volcano geopark.

Study of the Connection Between Yogyakarta – Sleman Groundwater Basin and Pajangan Hill (as a Non-Groundwater Basin Area) Using Groundwater Geochemistry and Isotope

Abstract This study investigates the hydrological connectivity between the Yogyakarta-Sleman Groundwater Basin (GWB) and the non-groundwater basin (non-GWB) area of Pajangan Hill using geochemical and isotopic methods. A total of 28 groundwater samples were analyzed for major ion content and isotopic composition, sampled from shallow wells, deep wells, and springs. Ion chromatography and cavity ring-down spectrometry were employed for analysis. The findings reveal that groundwater in Pajangan Hill predominantly consists of calcium bicarbonate, while Yogyakarta-Sleman GWB includes calcium bicarbonate, calcium nitrate, and sodium bicarbonate. Isotopic analysis indicates that water samples close to the Local Meteoric Water Line (LMWL) likely originate from local rainwater infiltration, maintaining their original isotopic composition. Despite some geochemical similarities, based on classification and composition analysis, significant differences in major ion concentration values suggest no hydrogeological connection between the two regions. The distinct lithologies, limestone in Pajangan Hill, and young volcanic deposits of Merapi in Yogyakarta-Sleman GWB further support this conclusion, indicating no hydrological connectivity between these areas.

Analytical solution for rainwater infiltration in monolithic soil covers under heavy rainfall and its implications for practice

This study established an analytical solution for rainwater infiltration in MSCs during heavy rainfall assuming that the soil hydraulic properties follow exponential forms. The analytical solution was used to calculate the factor of safety (FOS) of MSCs after the verification with numerical simulations. It is found that the FOS for the potential slip surface at the cover bottom remined the lowest during and after heavy rainfall. The percolation and FOS might present pronounced “lag effects”, meaning that the maximum percolation rate and minimum FOS occurred after heavy rainfall. A parametric study was conducted to reveal the influencing factors on the hydraulic response and slope stability of MSCs based on the analytical solution. Relevant results demonstrate that the hydraulic performance and slope stability could be improved by decreasing soil saturated hydraulic conductivity, increasing soil desaturation coefficient and lowering water level in landfills. The results also reveal the existence of a threshold of soil saturated hydraulic conductivity (1×10<sup>-8</sup> m/s for this study) for controlling the hydraulic performance and slope stability of MSCs. Furthermore, the analytical solution was applied to determine the rainfall intensity-duration threshold curves of MSCs. The results indicate that the obtained curves of MSCs satisfied exponential forms.

Numerical study of rainfall percolation through a novel capillary barrier cover with a zipper-shape interface between fine- and coarse-grained soils

The huge amount of leachate generated in landfills causes persistent pollution to soil and groundwater. Landfill cover is vital for reducing leachate generation through reducing rainwater infiltration. Yet, the traditional cover with capillary barrier effects (CCBE) is only applicable in reducing rainwater percolation at its base in arid or semi-arid region. To solve this problem, a novel capillary barrier cover is proposed, which adds multiple gravel-segments to the traditional CCBE to form the zipper-shape interface between fine- and coarse-grained soils. Hydraulic response of this zippered CCBE is numerically investigated considering different gravel-segment sizes, drainage-ditch widths and climate conditions. It is found that the zippered CCBE has a lower water percolation than the traditional one by up to 57 %. It is because the capillary barrier effects along the right side-wall of gravel-segment leads to water accumulation and hence water percolation near its base, facilitating reducing water percolation using drainage ditch below the gravel-segment. Moreover, water percolation increases when the gravel-segment height exceeds 0.3 times thickness of fine-grained soil or the gravel-segment width increases, due to reduction of water storage in fine-grained soil. Under the recorded annual precipitation of 1235 mm in the semi-humid region in China, the annual percolation of the traditional and zippered CCBEs are 84 mm/year and 36 mm/year, respectively. Thus, the zippered CCBE might extent the applicability of the traditional CCBE from arid or semi-arid region to semi-humid region.

Detection of Aquifer Infiltration Zones Using Resistivity and Induced Polarization Methods

Infiltration zones that are water providers for aquifers are often neglected, resulting in the sustainable use of groundwater resources will be disrupted. The research is intended to determine rainwater catchment areas as water suppliers for aquifers on the coast of East Tondano Beach. The location of the research is in the coastal area of East Tondano, Minahasa Regency. Exploration of subsurface rock layer detection using the resistivity geoelectric method and induced polarisation, dipole-dipole configuration, 10 m space. Data acquisition using multielectrode resistivity and IP meter MAE type X612-EM. The measurement line of the two methods is the same, the data was measured on 2 lines, with line 1 being 240 m long and line 2 being 360 m long. A rainwater infiltration zone with a resistivity of 48<ρ<192 Ωm was identified, on track 1 there was a infiltration zone at meters 105-135, a layer with low resistivity was identified at meters 70-150 with a resistivity of 3-48 Ωm and a depth of ≥ 15 m.. Based on the results of the IP meter, no suspected groundwater aquifer was found, so rainwater is estimated to flow directly into the sea. On line 2, the infiltration zone was detected at meters 80-105 and meters 275-315. The layer with a low resistivity value at 100-275 meters with a resistivity of 3-48 Ωm, has a depth of ≥ 20 m. The results of the IP measurement, layer with low chargeability ≤ 0.8 ms are found on the 180-200th meter. Suspected groundwater aquifer at 180-200 meters with a depth of 45-65 m. Keywords: Aquifer; resistivity; infiltration zones

Evaluation of the Effects of Rainwater Infiltration on Slope Instability Mechanisms

Mass movements can be caused by factors from different categories, such as geological factors and climate change. From a geological point of view, the soil profile and the geotechnical properties of the materials are crucial in influencing slope instability. From a climate change perspective, rainfall intensity is one of the main triggers of mass movements. Studies related to rainfall infiltration focus on saturated slope zones; therefore, areas of slope stability with infiltration in the unsaturated zone present large gaps. The Brazilian government environmental diagnostics company, the Mineral Resources Research Company (CPRM), identified the municipality of Areia/PB as a danger zone. The region has landslides that occur mostly during the rainy season. Such events lead to the presumption that rainwater infiltration is responsible for the failure of the municipality’s slopes. Thus, the studies proposed in this research aim to determine the influence of precipitation on the stability of the slopes present in the region. The results show that antecedent precipitation has a greater influence on stability, indicating that daily precipitation alone cannot be used as a determinant for landslides. It was concluded that the role of precipitation in slope stability will vary for different locations, with varying surface conditions, variable tropical rainfall, or different microclimatic conditions.

The Effects of Bedrock Topography and Soil Permeability on Saturated Zone Distribution in a Mountainous Steep‐Slope Area

ABSTRACTSaturation development and distribution at the soil–bedrock interface are important for predicting shallow landslide occurrence. Previous studies have indicated that saturation is generated in bedrock depressions and valleys and that bedrock groundwater seepage generates locally saturated areas. However, the effects of soil permeability, which is known to be heterogeneously distributed, on saturation development and distribution are poorly understood. In this study, we performed unprecedented high‐resolution (approximately 50 cm grid) soil pore water pressure and soil temperature monitoring using 141 tensiometer–thermocouple sets in a plot measuring approximately 5 × 4 m to investigate the effects of topography and bedrock groundwater seepage on saturation development and distribution. We then measured permeability distribution of two soil profiles, including at the soil–bedrock interface, using the Guelph Permeameter method (GP method) for comparison with saturated zone distribution and saturation duration. The results indicated that a perennial saturated area was formed by bedrock groundwater seepage and was distributed downstream from a certain bedrock surface altitude in the lower region of the study plot. After a peak of rainfall, the perennial saturated area expanded upslope owing to the increased seepage. In areas without the influence of bedrock groundwater, saturation was observed to retreat rapidly at high permeability points and persist over long periods at low permeability points; however, the saturation duration was inconsistent with the bedrock surface topography. Therefore, it is suggested that the bedrock altitude controls the saturation distribution generated by bedrock groundwater, whereas the distribution of saturation that is associated with direct rainwater infiltration may be controlled by the permeability distribution during recession periods. Although the plot size was small, the unprecedented high‐resolution observations suggest that the permeability distribution, rather than the bedrock topography, may control the saturated zone distribution following rainfall.

Numerical Simulations of a Permeability Test on Non-Cohesive Soil Under an Increasing Water Level

With the intensification of global climate change, extreme rainfall events are occurring more frequently. Continuous rainfall causes the debris flow gully to collect a large amount of rainwater. Under the continuous increase in the water level, the water flow has enough power to carry plenty of loose solids, thus causing debris flow disasters. The intensity of the soil is reduced with the infiltration of rainwater, which is one of the key causes of the disaster. The rise in the water level affects the infiltration behavior. There have been few previous studies on infiltration under variable head. In order to understand the infiltration behavior of soils under the action of water level rises, this paper conducted an indoor permeability test on non-cohesive soil under the condition of an increasing water level. A numerical model was established using the finite element analysis software, Abaqus 6.14, and the pore pressure was increased intermittently to simulate the intermittent increase in the water level. Thereafter, the permeability coefficient and seepage length were changed to interpret the changes in the flow velocity and rate in the permeability test of the non-cohesive soil. The results showed that the finite element numerical simulation method could not reflect the particle movement process in the soil. The test could better reflect the through passage and void plugging phenomenon in soil; when the permeability coefficient alone changed, the velocity of the measuring point with higher velocity changed more violently with the permeability coefficient; when the length of soil seepage diameter was uniformly shortened, the velocity of water flow increased faster and faster.

Investigating the impact of urban development on the activation of a paleolandslide. A case study from Pissouri, Cyprus

The present study investigates the reactivation of a paleolandslide due to the expansion of a community in an area covered by plastic Pliocene marls in the southwestern part of Cyprus. The landslide, which takes place in an area with gently sloping ground and relatively shallow water table, affects more than 100 residential buildings. In the context of the study, building damages and ground surface ruptures were mapped through field work campaigns. Remote sensing data from InSAR (Interferometric Synthetic Aperture Radar) analysis were evaluated in conjunction with available geological, geotechnical and hydrogeological data. Subsequently, the landslide was backanalyzed using the finite element method to examine possible failure mechanism scenarios and shed light on the influence of potential triggering factors. The results indicate that the paleolandslide has been almost fully reactivated, with the main cause of the reactivation being the rising of the phreatic water table due to long-term discharges of wastewater through the absorption pits of the residential developments. The water table rise was further amplified by rainwater infiltration during rainy years. According to the backanalysis results, the slip surface follows the bedding planes of weak marl horizons with residual friction angle of the order of 10°.

Anti-seepage performance and oxygen barrier performance of the three-layered landfill cover system comprising neutralized slag under extreme climate conditions

For acidic industrial solid wastes, an effective cover system is needed to reduce the rainwater infiltration and oxygen intrusion, thus reducing the generation of acid mine drainage (AMD) from wastes. A three-layered cover using low-permeability neutralized slag (abbreviated as TCNS) at the bottom of the traditional capillary barrier cover is proposed, in line with the novel concept of “waste protecting waste”. This study investigates the anti-seepage performance and oxygen barrier performance of TCNS under extreme climate conditions, through laboratory column test and numerical simulations. The results show that the water content of the neutralized slag (NS) layer remained stable (i.e., changed by less than 0.02) under either extremely wet condition or extremely dry condition. Under extremely wet condition (i.e., heavy rainfall corresponding to a 50-year return period), no water percolation was observed at the cover bottom; under extremely dry conditions, oxygen diffusion was greatly impeded, e.g., after 208 days of column test, the SO42− concentration in the AMD of the exposed (i.e., uncovered) waste rock was 4.6 times higher than that of the waste rock covered by TCNS. Numerical simulations considering two realistic climate conditions (i.e., humid and arid) showed that TCNS were effective in controlling water percolation and oxygen intrusion. The saturated permeability coefficient (ks) and initial saturation degree (Se) of the NS layer have significant effects on the performance of TCNS, i.e., decreasing ks or increasing Se can effectively reduce the water percolation and oxygen flux. In sum, TCNS is an effective barrier for controlling water percolation and oxygen intrusion, even in extreme climate conditions. Consequently, it can effectively minimize AMD leakage and thus reduce geological disasters such as groundwater contamination.

Stability analyses of non-homogeneous unsaturated slopes subjected to continuous rainwater infiltration

Stability analyses of non-homogeneous unsaturated slopes subjected to continuous rainwater infiltration

Isotope characterisation of groundwater resources in uranium impacted Fazilka, Punjab

AbstractGroundwater is the most reliable source for freshwater supplies in India and abroad. Population rise has affected the groundwater resources both in terms of quality and quantity. Punjab, being an agrarian state, is highly dependent on groundwater resources for both irrigation and drinking purposes. Recent studies have indicated presence of uranium in groundwater especially in southwestern parts of Punjab. In this research, water samples were collected from Fazilka district of Punjab for evaluating the water quality focussing uranium and identifying source and recharge processes of groundwater. Uranium concentration was found in both shallow and deep groundwater samples. Inter-ionic correlations signify that alkalinity and electrical conductivity of the water samples control the uranium mobilization from the aquifer matrix. Isotopic systematics demonstrate that groundwater recharge is mainly through rainwater infiltration.

Water Ecological Security Pattern Based on Hydrological Regulation Service: A Case Study of the Upper Hanjiang River

Water ecological problems involve flood, drought, water pollution, destruction of water habitat and the tense relationship between humans and water. Water ecological problems are the main problems in the development of countries all over the world. In terms of ecological protection, China has put forward the ecological red line policy. Water ecology is an important component of the ecosystem, and the delineation of the water ecological red line is an important basis for ecological protection. Based on ecosystem services, this paper tries to determine the red line of the water ecology space and tries to solve various water problems comprehensively. Based on the ecosystem services accounting method, the SWAT (soil and water assessment tool) model was used to simulate the spatial–temporal dynamic quantities of water purification and rainwater infiltration services in the upper reaches of the Hanjiang River. The basin was divided into 106 sub-basins and 1790 HRUs (hydrological response units). Water quality data taken from 8 sites were used to verify the simulation results, and the verification results have high reliability. The grid scale spatialization of water quality and rainwater infiltration is realized based on HRU. The seasonal characteristics of hydrological regulation and control services were analyzed, the red line of hydrological regulation and control in the upper reaches of the Hanjiang River was defined, and the dynamic characteristics of water ecological red line were analyzed. According to the research results, the water ecological protection strategy of the basin is proposed. The prevention and control of water pollution should be emphasized in spring and summer, the prevention and control of rain flood infiltration in autumn and winter, and the normal monitoring and management should be adopted in the regulation and storage. The results of this study can provide scientific reference for water resources management and conservation policy making.

Review of Assessing Slope Stability in Sabah: A Comprehensive Geotechnical Analysis

Rainfall has been recognized as the primary factor contributing significantly to landslide incidents globally. This is attributed to rainwater infiltration, resulting in fluctuations in groundwater levels, which play a crucial role in landslide occurrences. This article reviews the previous study on the relationship between rainfall intensity towards slope failure. A summary of the present research was conducted, and it is apparent that rainfall intensity is one of the elements that plays a role in landslides. Ultimately, rainfall leads to significant landslides, affecting pore pressure and frictional strength.

Numerical Modeling of Hydrological Mechanisms and Instability for Multi-Layered Slopes

The process of rainwater infiltration into unsaturated multi-layered slopes is complex, making it extremely difficult to accurately predict slope behaviors. The hydrological mechanisms in multi-layered slopes could be significantly influenced by the varying hydraulic characteristics of different soils, thus influencing slope stability. A numerical model based on Hydrus 2D was constructed to investigate the hydrological mechanisms of multi-layered slopes under different slope inclinations and rainfall intensities. The results revealed hydraulic processes in response to rainfall in unsaturated multi-layered slopes, in which layered soils retard the advance of wetting fronts and affect seepage paths in the slope. The results also showed the characteristics of hydraulic parameters, including pore water pressure and moisture content, under different conditions, and explained the crucial factors at play in maintaining slope stability.