Beginning Of Rainfall Research Articles

Using a rainfall simulator thrust type to evaluate the efficacy of insecticides in a apple orchard

A rainfall simulator thrust type was evaluated as a novel tool for studying the efficacy of insecticides against pests in apple orchards, compared to traditional laboratory methods. The simulator was installed and calibrated to simulate rainfalls of 50 mm h-1 on a 7-year-old apple orchard. The results of Grapholita molesta (Lepidoptera: Tortricidae) control in the field differed from those obtained in laboratory. The control efficacy in the orchard was lower than that obtained in laboratory tests. Control percentages varied throughout the simulated rains, with increases at the beginning of rainfall followed by decreases. The use of the push-type rainfall simulator provides advantages to research experiments, as it allows for evaluations under field conditions at different developmental stages of plants in orchards under different management practices, with results closer to field reality than those currently generated by laboratory tests.

Effects of expanding cassava planting and harvesting windows on root yield, starch content and revenue in southwestern Nigeria

Cassava (Manihot esculenta Crantz) is an important staple crop in Nigeria. It provides approximately 80 % of the caloric intake in Nigeria. High starch content and fresh root yields are important for the commercialization of cassava. Cassava is a perennial crop, and it can be produced all year round. However, cassava fresh root yield and starch content are strongly influenced by environmental conditions such as rainfall. Therefore, it is important to identify planting and harvest periods to attain maximum yields and starch content and to increase profitability. The present study aimed at (i) comparing changes in fresh root yields and starch contents of cassava planted and harvested at different times around the year (ii) identifying the cassava harvest phase attaining maximum fresh root yields and starch content (iii) assessing how price fluctuations and root yields affect the revenue and income generation across the year. This study was carried from 2017 to 2019 in southwestern Nigeria. Existing cassava fields planted at different months were visited and the planting dates were recorded. Harvesting for each planting month was done at 9, 11 and 13 months after planting (MAP). Fresh root yield and starch content varied across planting months. For all crop ages, the highest fresh root yields were recorded when planted in September and December. The highest root starch content was observed in 9- and 13-months old cassava when planted in March and November, respectively. Cassava fresh root yield and starch content varied across Julian day of harvest with lowest yields obtained between Julian day 60–120 (March and April) which coincides with the beginning of rainfall. Highest fresh root yields and starch content were attained between Julian day 180–330. Revenue showed seasonal variation and was dependent Julian day of harvest. Gross revenue was lowest between Julian day 60 and 120 (March and April) and highest from Julian day 180 (July). Lowest incomes or profits were recorded when cassava was harvested between Julian day 60 and 120 (March and April). About 9.1 % of farmers had negative revenues or lost income when they harvested at 9 MAP hence losing between 150 and 200 USD ha−1 compared with 2.8 % of farmers that lost income when harvesting was done at 11 and 13 MAP losing between 100 and 150 USD ha−1. Thus, farmers’ income generation critically depends on cassava planting and harvest dates. Choosing the right time to plant and harvest cassava is one of the most important decisions farmers can make to maximize profit.

The Progressive Failure Mechanism of the Tunnel-Slope System under Rainfall: An Experimental Investigation

Tunnel excavation has always been an important reason for the stability failure of the tunnel-slope system at the portal section. In case of rainfall, it is likely to cause serious disasters such as tunnel vault collapse, water inrush from the tunnel face, and slope slip. In this study, the Sunjiaya tunnel of the Daping slope group was taken as the engineering background, and the tunnel model experiment system under the condition of rainfall and groundwater seepage was designed independently to explore the failure laws of slope instability induced by tunnel excavation under the condition of rainfall. Meanwhile, a fiber grating monitoring system was also used to measure the displacement, water content, earth pressure, and seepage pressure at different positions of the tunnel-slope system in the process of tunnel excavation under the condition of rainfall. The results show that the slope instability caused by rainfall infiltration is gradual. At the beginning of rainfall, the rainfall infiltration has little effect on the stability of the tunnel-slope system and then gradually increases with the continuous rainfall. Finally, the slope surface is uneven, and the phenomenon of gully and surface flow is serious. The foot of slope moves back continuously, resulting in overall collapse. Moreover, during the process of tunnel excavation, the cracks on the tunnel vault of the unburied tunnel lining develop in quadratic along the tunnel excavation direction, and the closer to the excavation section, the larger the collapse range. Finally, there is an integral collapse of the vault of tunnel excavation section. In addition, variation laws of parameters in the tunnel-slope system also provide an important explanation for the hysteresis of the stability failure of the tunnel-slope system. The results have important guiding significance for the stability of the tunnel-slope system during construction.

Water Field Distribution Characteristics under Slope Runoff and Seepage Coupled Effect Based on the Finite Element Method

The unsaturated seepage field coupled with heavy rainfall-induced surface flow mainly accounts for the slope instability. If the slope contains macropores, the coupled model and solution process significantly differ from the traditional one (without macropores). Most of the studies on the variation of the water field under the coupled effect of runoff and seepage on the slope did not consider the macropore structure. In this paper, two coupled Richards equations were used to describe the MF (Macropore Flow), and along with the kinematic wave equation, they were applied to establish a coupled model of SR (Slope Runoff) and MF. The numerical solving of the coupled model was realized by the COMSOL PDE finite element method, and an innovative laboratory test was conducted to verify the numerical results. The effects of different factors (i.e., rainfall intensity, rainfall duration, saturated conductivity, and slope roughness coefficient) on water content and ponding depth with and without macropores were compared and analyzed. The results show that infiltration is more likely to happen in MF than UF (Unsaturated Flow, without macropore). The depths of the saturation zone and the wetting front of MF are obviously greater than those of UF. When SR occurs, rainfall duration has the most significant influence on infiltration. When macropores are considered, the ponding depth is smaller at the beginning of rainfall, while the effects are not obvious in the later period. Rain intensity and roughness coefficient have significant influences on the ponding depth. Therefore, macropores should not be ignored in the analysis of the slope seepage field.

Research on Rainwater Runoff Pollution in Different Blocks in Xi’an

By monitoring the changes of SS/COD/TP/TN in rainwater runoff in residential, industrial, commercial and traffic areas of Xi’an with the rainfall duration, the characteristics of rainwater runoff pollution in different areas of the city are explored. The results show that the concentration of pollutants in different regions from high to low is: traffic area>industrial area>residential area>commercial area. The concentration of pollutants in rainwater runoff in various regions reached a peak at the beginning of rainfall (within 30 minutes), and then gradually decreased and stabilized. The concentration of main pollutants in rainwater runoff in traffic areas is significantly higher than that in other areas. It can be seen that transportation may be the main factor affecting urban rainwater runoff pollution

Multi-Mode Surface Generalization Supports a Detailed Urban Flooding Simulation Model

With the aim of achieving high precision and high efficiency, recent research on hydraulic flood models has tended to focus on the algorithms for solving the shallow water equations of Saint-Venant. While development of the algorithms will help to improve the simulation precision and the solving of specific problems, the other influential factor in flood risk modeling is the precision and reasonable generalization of the data. This is even more important for increasing the model’s computational accuracy and efficiency but is frequently undervalued. Frequent rainstorm waterlogging is having a serious impact on China’s large cities. Early warning of waterlogging risk following a rainstorm forecast is an effective method for preventing or reducing potential losses. Concrete waterlogging information including locations, depth, and process is essential for early warnings. This paper focuses on the influence of data precision and reasonable generalization on an urban flooding model. A detailed hydraulic urban flooding model characterized by detailed data processing and component coupling can help to provide advance information. In Beijing city, road networks, overpasses, and buildings are so highly concentrated that rainstorms easily result in waterlogging in low-lying locations. Therefore, partial microrelief is the determinate factor in waterlogging simulation. This paper shows that multi-mode surface data generalization and detailed model coupling support a perfect simulation of a Beijing urban flooding model. The influence of buildings, roads, and overpasses on surface water flow was carefully considered based on the innovative aspect of a fine generalization of partial microrelief. One novelty is the simulation of the whole overland flow from the beginning of rainfall to mesh, not only from manhole overflow, because the waterlogging is caused mainly by initial surface water runoff rather than by manhole overflow. A second novelty is the use of a new kind of coupling mode based on physical mechanisms between surface and pipe models. Here, rain perforated strainers instead of manholes play a role as flow exchange points between pipe and surface. This coupling mode is much closer to the real world. Based on a detailed Beijing urban flooding model, a scenarios library of typical rainfall events and corresponding waterlogging results was constructed. Several years of practice have demonstrated that a rich library of scenarios can be used effectively for the quick identification and early warning of waterlogging risk for a forecast rainfall. Test results show that multi-mode surface generalization is effective in improving outcomes and useful for scientific decision making in controlling urban waterlogging.

Linking nitrate dynamics to water age in underground conduit flows in a karst catchment

Although numerous studies on nitrate transport and transformation in karst catchments have been reported, many challenges in understanding nitrate fluxes remain due to the unique architecture of karst critical zones and complex hydrological processes. Water age is an important descriptor of hydrological function providing insight to into flow paths and water sources at the catchment scale. This offers a potential opportunity to better understand the spatio-temporal variations in nitrate dynamics in karst catchments. We linked the nitrate dynamics of underground conduit flow to water age extracted from a robust tracer-aided model for a karst catchment in southwestern China. The results show that nitrate dynamics in underground conduit flow are controlled by the coupling of nitrate supply and of flow paths in the karst catchment. High contributions of drainage from small fractures water leads to low nitrate concentrations in underground conduit flow during the dry season. This reveals that the small fractures may be another important “hot spot” for denitrification leading to nitrate removal in the karst critical zone. The switching between transport limited and supply limited conditions cause the marked variations in nitrate concentration of underground conduit flow during wet season. Although rapid infiltration via large fractures and sinkholes have strong dilution effects on nitrate in underground conduit flow at beginning of rainfall, more nitrate was transported out of the catchment with drainage during rainfall events due to the mobilization of soil nitrate by rainfall. Meanwhile, the capacity to transport nitrate out of catchment can be potentially activated when the ‘old’ water is displaced by rainfall under high wetness condition.

The Influence of Horizontal Variability of Hydraulic Conductivity on Slope Stability under Heavy Rainfall

Due to the natural variability of the soil, hydraulic conductivity has significant spatial variability. In the paper, the variability of the hydraulic conductivity is described by assuming that it follows a lognormal distribution. Based on the improved Green–Ampt (GA) model of rainwater infiltration, the analytical expressions of rainwater infiltration into soil with depth and time under heavy rainfall conditions is obtained. The theoretical derivation of rainfall infiltration is verified by numerical simulation, and is used to quantitatively analyze the effect of horizontal variability of the hydraulic conductivity on slope stability. The results show that the variability of the hydraulic conductivity has a significant impact on rainwater infiltration and slope stability. The smaller the coefficient of variation, the more concentrated is the rainwater infiltration at the beginning of rainfall. Accordingly, the wetting front is more obvious, and the safety factor is smaller. At the same time, the higher coefficient of variation has a negative impact on the cumulative infiltration of rainwater. The larger the coefficient of variation, the lower the cumulative rainwater infiltration. The conclusions reveal the influence of the horizontal variation of hydraulic conductivity on rainwater infiltration, and then the influence on slope stability.

Effects of layering on triggering mechanisms of rainfall-induced landslides in unsaturated pyroclastic granular soils

Rainfall-induced landslides are widespread in shallow layered granular soil deposits. In many cases, slope instability is related to the decrease of suction during rainwater infiltration. However, the contrasts in the unsaturated hydraulic properties of the soils deeply affect the infiltration process, thus influencing slope failure. Coarse-textured soil layers embedded between finer ones may initially confine the process within the overlying finer layers, delaying the infiltration and eventually inducing lateral flow diversion. Nonetheless, depending on the state variables at the beginning of rainfall as well as on rainfall characteristics, the coarser layers may or may not have a positive effect on stability. The results of research based on advanced geotechnical characterization, physical and numerical modeling, and field monitoring have been analyzed to investigate the effects of layering on slope stability.

Flow field analysis of micro particles passing through pervious concrete

In order to study the pore seepage and clogging problems in the permeable concrete, the permeable concrete blockage test device was used to simulate the flow law and distribution of the surface micro-particles through the concrete at the beginning of rainfall. The internal pore structure was reconstructed by CT scanning technique combined with avizo software. The DPM model in CFD was used to simulate the multiphase flow of Kunming surface microparticles through the permeable concrete. The results show: The results obtained by CFD numerical simulation are in good agreement with the experiment. The surface micro-particles with particle size range of 200-500um have a certain degree of blockage to concrete, and still have good water permeability (higher permeability coefficient), and after adding below 200um The particle clogging is more significant, and the permeability coefficient is basically close to 0; but more importantly, it is found by DPM simulation that the small particles of 0-100 um pass through the concrete and the seepage velocity is slow and the partial adhesion to the wall of the tunnel causes the diameter to decrease and affect the seepage.

A Comparative Study of Developmental Differences in Soil Rill Network Runoff and Slope Sediment Production Process

To explore cultivated loessial soil and dark loessial soil rill network development and differences in slope runoff and sediment process. the three-dimensional laser scanning technology was used, the cultivated loessial soil and the dark loessial soil were taken as the research object, and the rain intensity of 60 mm / h and 90 mm / h was selected, and the simulated rainfall test of the 20 ° slope was carried out for 1 h. The results showed that the clay content of dark loessial soil was 2.5 times that of cultivated loessial soil. At the beginning of rainfall, the infiltration of black soil was slow, the runoff was earlier, and the runoff of slope was larger than that of loess. The landfall occurred earlier and the slope erosion was larger. but the cultivated loess soil is loose, poor in corrosion resistance and easy to be compacted by raindrops. In the second rainfall, the runoff on the loess slope was 1.4 times higher than that on the dark loess soil, and the erosion on the slope was higher than that on the dark loess soil. From the point of view of the development of rill net, the characteristic index of rill net of dark yellowed soil is larger than that of topsoil loess at the beginning of rainfall, but under the condition of rainfall in the middle and late period, the characteristic index of rill net of tilling layer loess is higher than that of dark loess. The rill development of cultivated yellow soil has the characteristics of late generation and fast development.

Modification of the isotopic composition of rainfall by throughfall and stemflow: The case of Scots pine and downy oak forests under Mediterranean conditions

AbstractMost hydrological studies based on stable water isotopes (18O and D) use the isotopic composition of rainfall as input signal. Although stable water isotopes are conservative tracers, previous studies have shown that canopies modify the isotopic composition of rainfall. At present, there is a scientific agreement about the factors involved in isotopic modification, but the effect of each factor and the magnitude of the isotopic shift are still not clear. In this study, we analyse at an interevent and intraevent basis the spatio‐temporal differences between the isotopic composition of rainfall, throughfall, and stemflow for two different species (Pinus sylvestris L. and Quercus pubescens Willd). The aim of the study is to analyse the isotopic modification that takes place in throughfall and stemflow and how meteorological variables and structural forest characteristics influence the observed changes. Rainfall and throughfall were sampled by a combination of bulk and sequential collectors, whereas stemflow was collected only by bulk collectors. Results showed that the isotopic modification occurred in both directions, although stemflow was consistently more enriched than throughfall. Despite the contrasting canopy structures, no significant differences between species were found. Moreover, the intraevent analysis suggested that all fractionation factors could occur during one event, but evaporation or isotopic exchange would have a higher impact at the beginning of rainfall, whereas canopy selection processes would be more important at the end of rainfall. Our results emphasize the importance of considering the isotopic composition of throughfall and stemflow in isotope‐related studies in forested catchments.

Simulation modeling for a resilience improvement plan for natural disasters in a coastal area

Floods are threats to ecosystems that are caused by natural disasters such as typhoons and heavy rain, and to respond to these threats, resilience needs to be improved. In this study, the response of the social-ecological system of Haeundae-gu (Busan, Republic of Korea) to disasters is analyzed by using a causal loop diagram, and a resilience improvement plan is presented by simulating the disaster resilience using green infrastructure through the System Resilience Dynamics Model. First, the resilience values are highest when green infrastructure is applied at the maximum applicable ratio (30%) compared with no application. Second, in the public and private areas of Haeundae-gu, resilience according to green roof scenario was higher until approximately 8 h after the beginning of rainfall, but then the resilience according to infiltration storage facility scenario was higher. In the transportation and industrial areas, the overall resilience according to infiltration storage facility scenario was higher than the resilience according to porous pavement scenario. This study demonstrates that a resilience improvement plan based on simulation can support decision making to respond to disasters such as typhoons.

The dynamic response of splash erosion to aggregate mechanical breakdown through rainfall simulation events in Ultisols (subtropical China)

Rainfall splash erosion is a temporal dynamic process that is determined by the interaction of soil surface and rainfall conditions. The properties of aggregate, such as aggregate stability and size distribution, are recognized as factors that influence the variation in soil surface structure and sediment selectivity during splash erosion event. This study based on aggregate stability to investigate the effect of aggregates breakdown dynamics on splash erosion and sediment size selectivity processes of Ultisols in subtropical China during rainfall events. Laboratory experiments of rainfall simulation involving rainstorm simulations at 58.1±2.8mmh−1 were conducted on four soils derived from Quarternary red clay and Shale. We compared the size distributions of aggregates produced by raindrop impact with the sediment size distributions resulted from transportation. Fractal dimension (D) and enrichment ratio (ER) were used to characterize aggregates size distribution and sediment size selectivity. Aggregates were prone to breakdown at the beginning of rainfall and a multiple regression equation (D=1.02RMI+1.77T0.06 (R2=0.95, P<0.01, n=60)) was obtained to describe aggregate breakdown dynamics considering a relative aggregate stability index (RMI) and rainfall time (T). Total masses of erosion sediment decreased as a power function with an increasing size fraction. The behaviors of sediment size fractions (<0.25mm, 0.5–0.25mm, 1–0.5mm, 2–1mm, 5–2mm) showed that the transport selectivity was decided by the interaction of aggregates size distributions and the characteristics of soil surface structure. Sediment size selectivity led to the enrichment of 1–0.25mm fraction compared with the breakdown products. This research contributes to knowledge about the dynamics of the splash mechanism, and the results could be valuable for the development of rainfall erosion models.

Intra-Annual Deposition of Atmospheric 210Pb,210Po and the Residence Times of Aerosol in Xiamen, China

Atmospheric deposition of 210Pb，210Po from Nov. 2010 to Jan. 2012 were analyzed to reveal their temporal variations, as well as applications in constraining the residence times of aerosol. The monthly depositional fluxes varied from 2.42 to 29.31 Bq/m2/mon and from 0.160 to 3.388 Bq/m2/mon for 210Pb，210Po, respectively. High fluxes of 210Pb，210Po were observed in the southwest monsoon prevailing months, while low fluxes corresponded to the northeast monsoon seasons, revealing the monsoon control over 210Pb，210Po deposition on seasonal timescales. There were significant positive linear correlations between the daily depositional fluxes and precipitation, supporting the predominant removal passage of 210Pb，210Po through rainfall. The inverse relations between specific activities and precipitation indicated that the removal efficiencies were much higher at the beginning of rainfall. In contrast, the dry deposition only accounted for 22% and 29% of the bulk depositional fluxes of 210Pb，210Po, respectively. The depositional flux ratios of 210Po to 210Pb varied between 0.015 and 0.223 with a mean of 0.091 ± 0.012, corresponding to the residence times of 3.1–57.5 d with an average of 20.8 ± 3.0 d. Investigations on size-fractionated 210Po and 210Pb could provide better understanding of the resident timescales of aerosol.

Research on Xilamuren Desert-Steppe Rainfall Experiment Segmentation Regular Pattern – Based on Rainfall Simulation Experiment

The rainfall is the main soil water supply to the soil of desert-steppe. It divides into three parts, evaporation, infiltration and runoff, after falling on to the surface. Those three parts are affected by many factors. Studies of rainfall division in desert-steppe were rare, the proportions of evaporation, infiltration and runoff are uncertain. So Under the condition of different vegetation, we conduct six times rainfall simulation experiment under different rainfall intensity. Simulation shows that rainfall process, the surface coverage and soil condition affect division. The evaporation section of rainfall accounted for 1/2 ~ 2/3. Infiltration section accounted for 30% ~ 50%. Runoff is the smallest. The rainfall intensity plays a decisive role on the runoff. Different vegetation coverage, division proportion is different. The interception and delay function of vegetation main effect evaporation and runoff, it can make the evaporation increased to more than 70%, reduce runoff to a third. Water content of soil profile before rainfall is the main factors affecting infiltration volume. The soil moisture before rain affects the infiltration rate at the beginning of rainfall. If rainfall duration is long enough, infiltration capacity is almost a constant.

Continuity in Wireless Video Security System-Based Physical Security Services

Traditional physical security policy considers an intentional use of budgets and a way of using physical spaces. It represents difficulties in responses to the environment, which is dynamically changed, because the plan is determined as static and stereotypical manners. Thus, in this study a wireless IP camera is used as a method that expands monitoring ranges in existing physical spaces in order to propose a security service structure that can support instantaneous detections and responses to disasters. Although the effort for protecting facilities and equipments using a video monitoring system using wireless IP cameras for temporal threats is a proper way for providing a physical security service according to needs of an adaptable security level. Moreover, if a security level for a specific section is to be upgraded according to changes in external environments, the security level, which is guaranteed by periodic guard patrols, can be improved and supported using a wireless IP camera-based video monitoring system for 24 h during the period to be required. Also, it is possible to establish an environment that enables instantaneous detections and responses for a moment of accidents through performing a continuous video monitoring work from the beginning of rainfall to a dangerous level of flooding.

금강유역 토지이용별 비점오염원 유출 특성 장기 모니터링 분석

본 연구의 목적은 금강유역에서의 비점오염원 유출 특성을 분석하고 이에 따른 비점오염원 관리 대책 수립의 기초자료를 제공하는 것에 있다. 이를 위하여 본 연구에서는 금강유역의 총 6개 지점을 모니터링 지점으로 선정하였으며, 2011년 3월 20일부터 9월 29일까지 장기간에 걸치 모니터링 관측을 수행하였다. 각 모니터링 지점에서는 자동 채수기 및 강우기록계를 통한 관측이 이루어졌으며, 관측 수질 항목 <TEX>$BOD_5$</TEX>, <TEX>$COD_{Mn}$</TEX>, SS, TN 및 TP에 대한 데이터 수집 및 분석이 이루어졌다. 분석 결과 비점오염물질은 강우 초기 유출을 통하여 쓸려 내려오며, 강우의 크기가 클수록 그 농도가 증가하는 것을 알수 있으며, 특히 SS의 농도가 상대적으로 크게 나타남을 알수 있었다. 따라서 본 연구에서는 이러한 장기간의 비점오염물질 관측 결과를 바탕으로 향후 금강유역에서의 토지이용에 따른 비점오염물질 원단위 산정을 위한 기초자료를 축적하였다. The aims of this study are the characterization of discharge from nonpoint source, the analysis of the pollutant loads and an establishment of a management plan for nonpoint source of Geum river basin. For this purpose, 6 monitoring points was selected to the investigated. During the period from March 20 to September 29 in 2011, the water automatic sampler system has been installed in each monitoring points and parameters such as <TEX>$BOD_5$</TEX>, <TEX>$COD_{Mn}$</TEX>, SS, TN and TP were analyzed. The nonpoint source pollutants seem to be washed out along the stream water in the beginning of rainfall, remain in water and cause the stream pollution. The runoff during heavy rainfall, especially, much higher concentration of SS than those during dry period. Therefore the basic data were build up to estimate the basin unit of nonpoint source according to land use in Geum river basin.

Old water contribution to streamflow: Insight from a linear Boussinesq model

Old water contribution to streamflow is studied by the means of a simple groundwater model. The principal aim is not to develop a tool for applications but rather to understand some of the dynamics of old and new water after a rainfall event by using a simple model with a minimum set of variables. Event water is traced by solute transport analysis. Adopting a simple rainfall pulse of finite duration, the method identifies two key dimensionless parameters ruling the old water contribution to streamflow: a dimensionless rainfall time δ, ratio between the rain duration and the characteristic response time of the aquifer, and the ratio ρ between rainfall volume and the water volume present in the aquifer at the beginning of rainfall. It was found that the ρ parameter is crucial in the old water contribution to a rainfall event; less so are the temporal dynamics of rainfall, expressed through δ. For typical values of ρ it is expected that old water contributes more than 50% of the total streamflow. These findings suggest that the groundwater dynamics may have a strong influence on the way that the hillslope responds to the rainfall input, and hence the partition between new (precipitation) and old (pre‐event) waters.

Centrifuge Model Test Study of Rainfall-Induced Deformation of Cohesive Soil Slopes

A rainfall simulation device was developed to realize uniform rainfall at high g-levels in centrifuge model tests. A series of centrifuge model tests was conducted on cohesive soil slopes during rainfall, and the displacement and suction of the slopes were measured. The slope exhibits a relatively shallow slide after a heavy rainfall, and exhibits a shear zone with significant deformation in the interior of the slope. The vertical displacement is significantly larger than the horizontal displacement of the slope during rainfall. The rainfall-induced displacement process can be divided into three phases: (1) small displacement, (2) rapid increase, and (3) large displacement with minor rate of increase. Strain analysis was conducted on the basis of the measured displacement, and the results showed that the rainfall-induced deformation of the slope is governed by two types of mechanisms: increasing overburden weight and softening of soil. For a point in the slope, the first mechanism occurs from the beginning of rainfall; and the second mechanism occurs only when the water infiltrates there, which is described using the wetting front. Accordingly, another term, stable front, describes a boundary of zero increment of deformation. These two fronts gradually advance into the slope with increasing rainfall and divide the slope into three zones. The middle zone exhibits the most significant deformation.