Groundwater Infiltration Research Articles

Monitoring Analysis of a Deep Foundation Pit with Water Supported by Cast-in-Place Pile and Internal Bracing in a Soft Soil Area of Fuzhou

In addition to selecting an effective support structure to control deformation, precipitation and water stopping should also be considered when designing a support scheme for water-bearing foundation pits in soft soil areas. This paper presents a detailed description of the foundation pit support scheme, the precipitation and water-stopping scheme, and the monitoring scheme of the foundation pit project of Taijiang Square in Fuzhou. During the construction of the foundation pit, the monitoring data of 12 items such as the deep horizontal displacement of the enclosure pile, the horizontal displacement at the top of the foundation pit, the settlement at the top of the foundation pit, the axial force of the internal bracing, and the axial force of the enclosure pile were obtained through 12 months of monitoring. The analysis of the monitoring data for each item led to the following two main findings. The first finding is that, during the construction of the pit, the monitoring values of the 12 monitoring items did not exceed the alarm values, which proves that the support scheme of the cast-in-place pile enclosure structure and internal bracing can meet the design requirements of deep foundation pits in soft soil areas. The second finding is that tube-well dewatering is an effective way to lower the groundwater level in water-containing deep foundation pits in soft soil areas, and double-wheel deep-mixing water-stopping curtain walls can effectively control the infiltration of groundwater outside the water-containing deep foundation pits in soft soil areas. This foundation pit project is representative, and it provides a good reference case for the design of water-bearing deep foundation pit projects in soft soil areas.

Hydrogeological controls on formation of Patearoa saline site in Central Otago, New Zealand and definition of geoecological salt lines

ABSTRACT The Patearoa saline site in Maniototo basin has developed on variably clay-altered Otago Schist. Decomposition and sedimentary redistribution of schist outcrop components has led to formation of bare soil-free substrates (upper metre scale) with contrasting permeability to rain and shallow groundwater percolation. Relatively impermeable clay-rich substrates, with a surface crust (cm scale) of detrital clay and muscovite, are saline with electrical conductivity (EC) of 1–35 mS/cm and locally hyperalkaline (pH > 10), with evaporative mineral accumulations. These saline substrates are downslope of more permeable substrates consisting of coarse schist debris and fractured outcrops, which have lower salinity (EC < 1 mS/cm) and lower pH (<7). A salt line can be mapped at metre scale between these substrate types on hillsides. The geochemical contrasts across the salt line have strong effects on plant communities that are colonising bare ground. Initial colonisation of bare saline substrates by some plants changes the geochemical signatures of the surficial few centimetres to form proto-soil with lower EC and pH. Proto-soil development facilitates further colonisation by pasture grasses, but the underlying substrates remain saline and highly alkaline. Salt lines similar to the one at Patearoa are mappable elsewhere in the Otago area and constitute fundamental geoecological boundaries.

Reduction of pollution loads based on sewage treatment projects around a lake: A case study on Erhai Lake.

Erhai Lake is a highland freshwater lake in Dali, China. Rapid tourism development has generated large amounts of pollutants. Since 2015, six wastewater treatment plants (WWTPs) have been built to treat wastewater collected through sewage interception projects. In this study, reductions in the pollution load of wastewater from different sources were evaluated by considering the effects of groundwater leakage, microbial degradation, and rainfall-runoff. The results showed that the systems reduced the chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) loads by 85, 83, and 85%, respectively. Discharge wastewater has the characteristics of a low concentration of domestic sewage discharge, large tourist sewage discharge, and high concentration of livestock wastewater. Due to the high groundwater level, there is groundwater infiltration in the influent water of WWTPs, which dilutes the pollutant concentration of the influent and, therefore, results in a lower treatment efficiency. Further treatment of tailwater also reduced the pollution loads discharged into the lake as well as the COD and TN by 10.25 and 22.90%, respectively. The results indicate that groundwater infiltration in the sewer network system is the primary target to be addressed in future developments.

Pollution Level, Ecological Risk Assessment and Vertical Distribution Pattern Analysis of Heavy Metals in the Tailings Dam of an Abandon Lead–Zinc Mine

Tailings dams in mining areas frequently experience the phenomenon of haphazard dumping and stacking of a large amount of tailings waste. Under the influence of surface runoff and groundwater infiltration, heavy metals from tailings waste can migrate to the surrounding areas and underground soil, resulting in extensive heavy metal pollution. To analyze the pollution level and ecological risk of heavy metals in an abandoned lead–zinc mine tailings dam, this study first employed X-ray fluorescence analysis to determine the vertical distribution patterns of heavy metals with depth. Then, the pollution levels of heavy metals were analyzed based on the Nemerow comprehensive pollution index and geoaccumulation index. Subsequently, the ecological risk of heavy metal pollution was further assessed using the potential ecological risk (PER) index. Finally, the sources and potential hazards of heavy metal pollution were investigated. The results reveal that (1) heavy metal pollutants are identified as lead (Pb), zinc (Zn), copper (Cu) and arsenic (As), displaying enrichment at the interface layer between the reclaimed zone and tailings layer with the highest concentrations; (2) the pollution degrees in each zone follow the order of interface layer &gt; tailings layer &gt; deep zone &gt; reclaimed zone, and the pollution levels for the four heavy metals in decreasing order are Pb &gt; Zn &gt; As &gt; Cu; (3) after considering the toxic effects of heavy metals, the potential ecological risk in each zone remains consistent with the ranking of pollution levels, and the contribution of the four heavy metals to PER changes to Pb &gt; As &gt; Zn &gt; Cu, corresponding average Eri values of 913.928, 416.900, 96.462 and 47.998, respectively; (4) ecological risk of heavy metals originates from lead–zinc ore extraction, and heavy metal pollution poses potential risks to public water security and surrounding ecological resources.

STUDI PEMANFAATAN CANGKANG KEPITING (Scylla sp.) UNTUK FILTER AIR TANAH DI KOTA TARAKAN

The city of Tarakan has the potential of ground water for clean water needs. But for its use, it nedds to be treated first so that the quality is in accordance with the required quality standards. Crab shell (Scylla sp.) waste is used as a filtration technology for water treatment. The purpose of this research was to study the effetiveness of using crab shells as a ground water filter in Tarakan City. The research method used in this study was an experimental method with a complete random design (RAL). Repetition was done three times. The material used was crab shell with a filter level of 30, 60 and 100 cm. Crab shells were combined with the use of activated charcoal, quartz sand and gravel to determine the best composition. The parameters that were tested according to the Regulation of the Minister of Health No. 32 of 2017 (Water Quality Standards for Sanitary Hygiene Needs) are turbidity, color, odor, pH, Temperature, TSS, TDS, nitrate, nitrite, iron (Fe) and manganese (Mn). The study’s findings demonstrated that the crab shell’s filtering effectiveness is quite low. For the pH parameter, the effectiveness value increased succcessively based on the filter level of 30,60 and 100 cm which was 54, 71, 80% and the Mn paraneter successively was 74, 92 and 81%. While the parameters of turbidity, color, TDS, TSS, nitrite, nitrate, and iron actually decreased the value of water quality, when compared to the value of standard water.

Influences of Underwater Shield Tunnelling on River Embankment Seepage Stability Considering Various Overburden Thickness

Underwater shield tunneling will disturb the soil near the river, especially in water-rich soft ground. This may cause a groundwater infiltration hydraulic gradient to exceed the critical value, leading to calamities, such as unexpected flooding or submerged erosion. To ensure the security of construction and the stability of river embankment seepage, it is crucial to assess the safety of the underwater tunnel cover thickness. A shield tunnel project under a river in Hefei is used as an example. The numerical model established by the finite element method is used for calculating and analyzing the changes in the groundwater flow field and the stability state of embankment seepage induced by underwater shield tunneling under different overburden thickness conditions. The results show that the construction disturbance of the shield tunnel through the river is increased, the internal force environment of the embankment slope is destroyed, and the maximum seepage hydraulic gradient is increased. In the case study, the embankment keeps in a stable state of seepage when the cover thickness of the shield tunnel has 2.9 times its outer diameter. The findings of this study can serve as a scientific guide to assure seepage stability in an underwater shield tunneling project and to stop river embankment erosion.

Hyporheic flow in aquatic Ranunculus habitats in temperate lowland rivers in Central Europe

The study attempted to assess the influence of the filtration stream and hydraulic gradient in the hyporheic zone on the distribution of water crowfoot (Ranunculus sect. Batrachium) in common temperate lowland river type in two European ecoregions: (14) Central Plains and (16) Eastern Plains. A novel filtrometer and a gradient meter were employed for water flow measurements in the hyporheic zone at 24 study sites distributed throughout Central Europe between 2017 and 2019. At the majority of the study sites, hyporheic zones covered with Ranunculus vegetation were found to be dominated by groundwater drainage. Moreover, the intensity of groundwater filtration supplied via the hyporheic zone varied, ranging from 0.0017 m3 d−1·m−2 to 0.4118 m3 d−1·m−2. It was also determined that the average stream of filtration in the non-vegetated parts of the riverbed was 0.6065 m3 d-1·m−2, whereas it was five times lower in the zones overgrown with Ranunculus clumps, amounting to 0.1190 m3 d−1 m−2. The study provides quantification of the interactions between water exchange in the hyporheic zone and the growth and distribution of Ranunculus species, indicating that the exchange of surface water and groundwater is an important environmental factor that stimulates the growth of various Ranunculus taxa. The study provides evidence for a new environmental indicator, specifically the importance of surface water and groundwater exchange in the hyporheic zone of rivers for Ranunculus vegetation conservation and for planning and implementing nature-based river management methods.

Acquisition of Spatial and Temporal Characteristics of Shallow Groundwater Movement Based on Long-Term Temperature Time Series in the Kangding Area, Eastern Tibetan Plateau

Heat has been widely used as a groundwater tracer to determine groundwater flow direction and velocity in a way that is ubiquitous, low-cost, environmentally friendly, and easy to use. However, temperature observations are generally short-term and small-scale, meaning they may not be able to reflect long-term changes in the characteristics of groundwater movement. In this study, we utilize 515 days of temperature data, collected from four measurement points in the Kangding area of the eastern Tibetan Plateau, in order to determine the spatial and temporal distribution of groundwater flow velocities using different analytical heat tracing methods. An analysis is conducted to evaluate the impact of thermal parameter uncertainties on the calculation of flow velocity, and a comparison is undertaken between the results of the phase, amplitude, and combined amplitude-phase methods. We subsequently discuss the relationship between flow velocity changes and precipitation. The results show that the estimated flow velocity is more susceptible to the volumetric heat capacity of the saturated sediment than it is to thermal conductivity. The phase method is more suitable for use in calculations in the study area, indicating that precipitation significantly impacts the flow velocity and that this impact is more pronounced in areas with flat terrain compared to areas with significant variation in elevation. Our research provides a comparative study of the heat tracing methods in areas with varied terrains and offers new evidence for the impact of precipitation and topography on groundwater infiltration.

Constructing GRACE-Based 1 km Resolution Groundwater Storage Anomalies in Arid Regions Using an Improved Machine Learning Downscaling Method: A Case Study in Alxa League, China

Using the Gravity Recovery and Climate Experiment (GRACE) satellite to monitor groundwater storage (GWS) anomalies (GWSAs) at the local scale is difficult due to the low spatial resolution of GRACE. Many attempts have been made to downscale GRACE-based GWSAs to a finer resolution using statistical downscaling approaches. However, the time-lag effect of GWSAs relative to environmental variables and optimal model parameters is always ignored, making it challenging to achieve good spatial downscaling, especially for arid regions with longer groundwater infiltration paths. In this paper, we present a novel spatial downscaling method for constructing GRACE-based 1 km-resolution GWSAs by using the back propagation neural network (BPNN) and considering the time-lag effect and the number of hidden neurons in the model. The method was validated in Alxa League, China. The results show that a good simulation performance was achieved by adopting varying lag times (from 0 to 4 months) for the environmental variables and 14 hidden neurons for all the networks, with a mean correlation coefficient (CC) of 0.81 and a mean root-mean-square error (RMSE) of 0.70 cm for each month from April 2002 to December 2020. The downscaled GWSAs were highly consistent with the original data in terms of long-term temporal variations (the decline rate of the GWSAs was about −0.40 ± 0.01 cm/year) and spatial distribution. This study provides a feasible approach for downscaling GRACE data to 1 km resolution in arid regions, thereby assisting with the sustainable management and conservation of groundwater resources at different scales.

Study on properties of representative ordinary Portland cement: Heavy metal risk assessment, leaching release kinetics and hydration coupling mechanism

As an important basic material in the construction industry, the potential harm of heavy metal elements contained in Portland cement (PC) to the ecosystem and human health cannot be ignored. In this research, PC from five representative areas of China was chosen to systematically research its heavy metal risk assessment, leaching release kinetics and hydration coupling mechanism using the advanced scientific testing techniques and research methods, so as to provide reasonable suggestions for the efficient, safe and environmentally friendly utilization of PC. The research indicated that the chemicalconstituents of PC are CaO, SiO2, Al2O3, Fe2O3, etc. The primary mineral composition were calcite, quartz, magnesite and mullite. Through the detection and analysis of the contents of Cr, As, Cd and Pb in PC, in accordance with the analysis results of environmental evaluation model, there were no obvious environmental risks of the four heavy metals, but the contents of Cr and Cd in PC need to focus on. At the same time, Cr in PC needs to be key-point controlled as human health risk assessments indicated that they posed a carcinogenic risk to the human body through oral administration. However, as the cumulative effect of As and Pb, their toxicity cannot be ignored in human health evaluation. Therefore, As and Pb need to be re-incorporated into the category of characteristic noxious heavy metals. But the control level was marked as medium; Cr and Cd control level was high.The fitting results of release kinetics showed that most of the heavy metal leaching in PC can be well fitted by Elovich model and second-order kinetic model. This indicated that Elovich model, second-order kinetic model and parabolic model were more worthy of study in the leaching release kinetics of heavy metals. In the meantime, the study showed that the leaching of heavy metals in PC was controlled by a series of effects such as parabolic model. On the basis of the dynamic model of heavy metal content in five kinds of PC with curing duration, the optimum safe age of noxious heavy metals in PC after PC hydration was explored. Through XPS test results, it was discovered that the Cr, As, Cd and Pb in PC present in the formation of Cr3+, Cr6+, As3+, As5+, Cd2+ and Pb4+. These noxious heavy metal ions were harmful to the human body by means of the infiltration and migration of soil and groundwater. Lastly, the hydration coupling mechanism of heavy metals in PC were discussed, and the content of characteristic heavy metals in PC under various usage scenes were limited.

Exploration on wastewater-based epidemiology of SARS-CoV-2: Mimic relative quantification with endogenous biomarkers as internal reference

Wastewater-based epidemiology has become a powerful surveillance tool for monitoring the pandemic of COVID-19. Although it is promising to quantitatively correlate the SARS-CoV-2 RNA concentration in wastewater with the incidence of community infection, there is still no consensus on whether the viral nucleic acid concentration in sewage should be normalized against the abundance of endogenous biomarkers and which biomarker should be used as a reference for the normalization. Here, several candidate endogenous reference biomarkers for normalization of SARS-CoV-2 signal in municipal sewage were evaluated. The human fecal indicator virus (crAssphage) is a promising candidate of endogenous reference biomarker for data normalization of both DNA and RNA viruses for its intrinsic viral nature and high and stable content in sewage. Without constructing standard curves, the relative quantification of sewage viral nucleic acid against the abundance of the reference biomarker can be used to correlate with community COVID-19 incidence, which was proved via mimic experiments by spiking pseudovirus of different concentrations in sewage samples. Dilution of pseudovirus-seeded wastewater did not affect the relative abundance of viral nucleic acid, demonstrating that relative quantification can overcome the sewage dilution effects caused by the greywater input, precipitation and/or groundwater infiltration. The process of concentration, recovery and detection of the endogenous biomarker was consistent with that of SARS-CoV-2 RNA. Thus, it is necessary to co-quantify the endogenous biomarker because it can be not only an internal reference for data normalization, but also a process control.

Water quality assessment in dry regions using statistical methods

Water demands have increased even more in recent decades because of the high population density. Surface and groundwater resources are insufficient to meet these demands. As a result, governments have turned to the treatment of sewage water. Sewage water contains multiple types of contamination, creating a major health risk. In the research region, 48 water samples were obtained, including 18 samples of surface water and 30 samples of groundwater. The Canadian Council Water Quality Index (CCWQI) program calculates the water quality index to evaluate the water quality for drinking and human use. The World Health Organization (WHO) and the Egyptian Ministry of Health (EMH) determined regulatory limits for drinking water and each value of the investigated parameter connected with them. According to the findings, 79% of the tested water samples are safe to drink and are excellent for human and wildlife use. Due to infiltration or recharging of groundwater with drainage water, as well as the involvement of dissolution, leaching processes, and anthropogenic activities that damage human health, animals, and some plants, these samples are unfit for drinking and domestic consumption. The heavy metal level of Cd and Pb in the examined water samples was found to be above WHO and EMH acceptable limits. Furthermore, due to oral exposures, the examined water samples may cause complex health concerns such as non-carcinogenic and carcinogenic influences for children over adults due to a reduction in children's immunity. As a result, water treatment should be carried out in the examined region to protect the health of the residents.

Groundwater recharge in typical geomorphic landscapes and different land use types on the loess plateau, China

AbstractLand use significantly affects the rate and amount of groundwater recharge. To understand these patterns, stable isotope analyses (δ2H and δ18O) and hydrochemical methods were employed to study the recharge and evolution of groundwater. MixSIAR Bayesian mixture modelling and statistical regression techniques were utilized to investigate the influence of land‐use type on groundwater recharge and to calculate the contribution of various water sources to different groundwater types. These findings are important for effective management and conservation of groundwater resources. The groundwater in all studied areas displayed a magnesium bicarbonate type with notable cation exchange, and also demonstrated the dissolution of carbonate and weathering of silicate. Results from the Bayesian mixture model indicate that 69.3% of the groundwater in the Loess Plateau region was recharged by precipitation, while 86.9% of the groundwater in the loess hilly‐gully region was recharged from the surface water. Groundwater recharge was more rapid in the loess hilly‐gully region than in the Loess Plateau and was less sensitive to the land use type in the former. Dryland‐moderate coverage grassland was found to be most conducive to groundwater infiltration, whereas monotypic dryland and high‐coverage grassland inhibited infiltration to some degree. To maintain balanced soil erosion control, an increase the area of moderate‐coverage grasslands in the Loess Plateau region is recommended.

Earthquakes evoked by lower crustal flow: Evidence from hot spring geochemistry in Lijiang-Xiaojinhe fault

Geothermal fluid is considered to be one of the important methods of earthquake forecasting, and some achievements have been made in previous studies. However, there is still a lot of work to be done before geothermal fluid can actually be used for earthquake forecasting. Lijiang-Xiaojinhe fault (LXF) which is a quake-prone region that lies on the border of Tibetan Plateau and Yangtze block is a good natural experimental field for earthquake research. In this contribution, we performed a systematic hydrogeochemistry and isotopic analysis of the geothermal waters and gases in the LXF zone. High Cl- (0.69–529.44 mg/L) concentrations in hot springs indicate that they are contaminated by deep fluid obviously. Further continuous observation (2020–2022) indicates that there are at least four times correspondence between ion concentration in two hot springs (Jinhe (94) and Xiaoshuiping (331)). Two earthquakes (ML5.2 earthquake on January 02, 2022 and ML4.6 earthquake on April 16, 2022) in Ninglang are only 50 km away from 331 hot spring, and obvious abnormal concentrations of Cl-, Na+ and SO42- were observed before the earthquakes. Combined with geological background and previous studies, we propose that lower crustal flow could be the reason why earthquake-prone in LXF. The lower crust flow through the LXF from northwest to southeast, causes internal deformation of the LXF zone. Then, a large amount of groundwater infiltrates deep underground along the fault, strengthens the pore fluid pressure, promotes the water–rock reaction, weakens fault zone, and trigger earthquakes. Ion concentrations in hot springs are sensitive to seismic activity in LXF. Unusually high or low ion concentrations in hot springs could represent the process of earthquake development, monitoring proper geothermal waters and gases in LXF will help us to study the pre-seismic hydrochemical precursors, and have a potential to provide important bases for earthquake forecasting.

The Surface Settlement Law of Precipitation in Pile-Beam-Arch Station Adjacent to Pile Foundation

The pile foundations of adjacent buildings can have an impact on the precipitation process in subway stations. In this paper, surface settlement monitoring is carried out by precipitation of horizontal wells in subway stations, and the law of surface settlement change with and without neighboring pile foundations is studied. The influence law of surface settlement in subway stations under different pile depth, different pile spacing and different distance between piles and station boundary is obtained through numerical simulation. Three models of groundwater infiltration in the adjacent pile foundation were established, the principle of pile-soil permeability coefficient equivalence was proposed, and the function relationship between the equivalent soil permeability discount factor and pile parameters was derived. The research results show that the surface settlement is smaller when there are piles in the measured precipitation process than when there are no piles. The greater the pile depth, the smaller the pile spacing and the smaller the pile-station boundary, the stronger the barrier effect and the smaller the final settlement of the ground surface. The accuracy of the formula is also analyzed to show that changing the pile parameters also changes the permeability coefficient of the piles and the soil between the piles. The station surface settlement law is related to the pile parameters, and the study can provide an important theoretical reference for the construction of precipitation with adjacent pile foundations.

METHOD OF ESTIMATING JOINT USE OF GROUNDWATER IN TRANSBOUNDARY AQUIFERS ON MATHEMATICAL MODELS

The methodological approach to solving the problems of optimal sharing of transboundary groundwater is determined as a result of mathematical modelling. Differential equation reproduces the confined-unconfined filtration of groundwater in the multi-stratified system as the basic approximation. Must be considered a single flow of underground waters, whose existence and properties depend on the areas of supply and discharge, which may be located in the territories of different countries. For regulation of transboundary water use the following criteria are suggested: quantitative estimation of ground and surface water depletion due to long time water discharge, calculation of extending time from contamination sources, identification of unknown location a possible source of contamination by groundwater flow velocity inversion. As an example, the results of modelling of cross-border flows underground in the territories Russia-Ukraine and Russia-Kazakhstan are given. The hydrodynamic math models have to be a subsystem of the total monitoring. Using such approach, both geological service and government authorities meet the real instrument for assessing and forecasting conditions of underground hydrosphere and efficient regulating of the anthropogenic load.

Mapping Potential Water Resource Areas Using GIS-Based Frequency Ratio and Evidential Belief Function

Groundwater is a critical freshwater resource that is necessary for sustaining life. Thus, targeting prospective groundwater zones is crucial for the extraction, use, and management of water resources. In this study, we combined the remote sensing, GIS-based frequency ratio (FR), and evidential belief function (EBF) techniques into a model to delineate and quantify prospective groundwater zones. To accomplish this, we processed Shuttle Radar Topography Mission (SRTM), Landsat-8 Operational Land Imager (OLI), Sentinel-2, and rainfall data to reveal the geomorphic, hydrologic, and structural elements and climatic conditions of the study area, which is downstream of the Yellow River basin, China. We processed, quantified, and combined twelve factors (the elevation, slope, aspect, drainage density, lineament density, distance to rivers, NDVI, TWI, SPI, TRI, land use/cover, and rainfall intensity) that control the groundwater infiltration and occurrence using the GIS-based FR and EBF models to produce groundwater potential zones (GWPZs). We used the natural breaks classifier to categorize the groundwater likelihood at each location as very low, low, moderate, high, or very high. The FR model exhibited a better performance than the EBF model, as evidenced by the area under the curve (AUC) assessment of the groundwater potential predictions (FR AUCs of 0.707 and 0.734, and EBF AUCs of 0.665 and 0.690). Combining the FR and EBF models into the FR–EBF model increased the accuracy (AUC = 0.716 and 0.747), and it increased the areas of very high and moderate potentiality to 1.97% of the entire area, instead of the 0.39 and 0.78% of the FR and EBF models, respectively. The integration of remote sensing and GIS-data-driven techniques is crucial for the mapping of groundwater prospective zones.

Penerapan Biopori pada Halaman Rumah Warga RT.01 RW.04 Desa Kuwaron Kecamatan Gubug Kabupaten Grobogan Jawa Tengah

&lt;p align="justify"&gt;&lt;em&gt;The people of Kuwaron Village, especially residents of RT.01 RW.04, have recently had problems of environmental damage, namely floods during the rainy season and drought during the dry season. The impact is the reduction of water catchment areas around the houses of residents of Kuwaron Village RT.01 RW.04. The purpose of this activity is to provide insight and skills regarding applying appropriate techniques for porous infiltration holes. In the hope of increasing groundwater reserves, reducing inundation, and accelerating water infiltration in residents' yards. The bio-pore-making training involved several residents of Kuwaron Village. Bio pores are made with a diameter of 10 cm and a depth of 100 cm. Then, the hole filled with organic kitchen waste. That is expected to reduce organic kitchen waste from each house because porous infiltration holes containing garbage invite various soil fauna and form pores to increase groundwater infiltration. The results of the evaluation of bio pores installation for four weeks showed that the rain puddles in the residents' yards receded faster.&lt;/em&gt;&lt;/p&gt;

Triggering of Rain-Induced Landslides, with Applications in Southern Italy

Landslides cause fatalities, widespread damages and economic losses. Quite frequently, they are triggered by rainfall. Many studies have investigated the relationships between rainfall characteristics and landslide events. This paper reviews the two main approaches, physical and hydrological, for modelling such relationships. In the physical approach, the influence of rainfall on slope stability is commonly analysed in terms of groundwater infiltration, pore pressure changes and balance between shear stresses and resistances, therefore a considerable amount of hydrogeological, morphological and geotechnical data is required. In the hydrological approach, a statistical-probabilistic study of rainfall series and dates of occurrence of slope movements is instead carried out. Both types of methods are briefly presented, with examples from real applications to study cases in Southern Italy. In particular, the recent reactivations of a large rockslide in Northern Calabria have been modelled by means of physical and hydrological approaches. In addition, shallow landslides in Calabria, Campania and Sicily have been modelled by employing hydrological approaches. Strengths and weaknesses of the adopted methods are discussed, together with the causes that may have hindered better results for the considered cases. For the methods illustrated through real application cases, research perspectives are discussed, as well as their possible use in early warning systems.

Centrifuge modelling of unsaturated slopes subjected to the integrated effect of groundwater and rainfall infiltration

The stability of unsaturated soil slopes is comprehensively discussed with the rainfall characteristics. However, pre-existing groundwater table is also common in many tropical mountainous regions. Additionally, perched water table could be generated due to antecedent rainfall conditions on the soil-bedrock interface. The complex hydrological response process of slopes subjected to the integrated effect of groundwater and rainfall infiltration has not yet been entirely realized. Therefore, the current studyaimed at investigating the influence of initial groundwater table on initiation of landslides in slopes exposed to rainfall infiltration. The centrifuge modelling technique is utilized in this study. A centrifuge container was newly designed to reproduce the rainfall and groundwater table effects. Identical soil slopes made from silty sand were tested under 50g conditions. The unsaturated slopes behaviour was evaluated under two cases during the analysis: 01) rainfall only and 02) rainfall on a pre-existing groundwater table. The results demonstrated that the failure happened in case (02) was quicker, larger in volume and faster to respond to rainfall infiltration. The factor of safety calculated using the infinite slope equations portrayed a slight mismatch of failure timing compared to the experimental results. These results suggested i) a higher risk ofslope failure under pre-existing groundwater flow and ii) acceleration of the progression of landside due to a potential surcharge flow.