Groundwater Table Depth Research Articles

Development and evaluation of a simple hydrologically based model for terrestrial evapotranspiration simulations

Following the scheme of the groundwater-soil-plant-atmosphere continuum (GSPAC), a simple process-based model (SiTH; Simple Terrestrial Hydrosphere) was developed to estimate the dynamics of terrestrial evapotranspiration (ET) at the daily step. The input data include net radiation, air temperature, precipitation, leaf area index, vegetation type and soil data, most of which are readily available. Locally, the model performed well in simulating the dynamics of ET and soil moisture over selected FLUXNET sites. Globally, the daily 0.25° ET and groundwater table depth estimations in year 2005 were determined using available gridded datasets. The spatial pattern was reasonable and the range of values corresponded well with other global ET and groundwater table depth products. In future studies, we will produce a long-term daily 0.25° global ET and groundwater table depth products that spans from 1984 to present by using different input datasets.

PEAT-CLSM: A Specific Treatment of Peatland Hydrology in the NASA Catchment Land Surface Model.

Peatlands are poorly represented in global Earth system modeling frameworks. Here we add a peatland-specific land surface hydrology module (PEAT-CLSM) to the Catchment Land Surface Model (CLSM) of the NASA Goddard Earth Observing System (GEOS) framework. The amended TOPMODEL approach of the original CLSM that uses topography characteristics to model catchment processes is discarded, and a peatland-specific model concept is realized in its place. To facilitate its utilization in operational GEOS efforts, PEAT-CLSM uses the basic structure of CLSM and the same global input data. Parameters used in PEAT-CLSM are based on literature data. A suite of CLSM and PEAT-CLSM simulations for peatland areas between 40°N and 75°N is presented and evaluated against a newly compiled data set of groundwater table depth and eddy covariance observations of latent and sensible heat fluxes in natural and seminatural peatlands. CLSM’s simulated groundwater tables are too deep and variable, whereas PEAT-CLSM simulates a mean groundwater table depth of −0.20 m (snow-free unfrozen period) with moderate temporal fluctuations (standard deviation of 0.10 m), in significantly better agreement with in situ observations. Relative to an operational CLSM version that simply includes peat as a soil class, the temporal correlation coefficient is increased on average by 0.16 and reaches 0.64 for bogs and 0.66 for fens when driven with global atmospheric forcing data. In PEAT-CLSM, runoff is increased on average by 38% and evapotranspiration is reduced by 19%. The evapotranspiration reduction constitutes a significant improvement relative to eddy covariance measurements.

Detection of land subsidence and its relationship with land cover types using ESA Sentinel satellite data: a case study of Quetta Valley, Pakistan

ABSTRACTThis paper presents the analysis of land subsidence as a result of excessive groundwater abstraction for irrigation and domestic supply in Quetta valley, Pakistan. The European Space Agency (ESA) Sentinel–1 and Sentinel–2 satellite data is used to identify and categorize the spatial distribution of land subsidence. The aquifer geology and observed groundwater table are used to establish the relationship between land subsidence and groundwater abstraction. For this, we performed Persistent Scattering Interferometry (PSIn) analysis using the Sentinel–1 Synthetic Aperture Radar (SAR) imagery to develop 28 maps of land subsidence covering a period of 16 October 2014 to 22 November 2016. The interferometry results matched well with the land subsidence values measured at the Global Positioning System (GPS) ground station with a mean absolute error of 5.7 mm and coefficient of determination of 0.94. The land subsidence values at each pixel of the map were classified according to the land cover types of the study area. Here, the map of land cover types was developed using the multispectral image of Sentinel–2A satellite. The results revealed that, during the 2–year period, the entire study area has suffered from varying degree of accumulated land subsidence ranging between 10 and 280 mm in magnitude, which was linearly proportional to the depth and drawdown of groundwater table observed at four piezometers located in the study area. The magnitude of land subsidence across the study area showed a strong correlation with land covers. The urban area and orchard vegetation with a large amount of groundwater abstraction showed an excessive amount of cumulative land subsidence, while the seasonally cultivated and barren land are slightly affected by land subsidence.

Determination of Planting Time of Watermelon Under a Shallow Groundwater Table in Tidal Lowland Agriculture Areas of South Sumatra, Indonesia

AbstractWatermelon cultivation is one of the appropriate alternatives in order to increase farmers' income from tidal lowland agriculture. Research into crop adaptation to wet soil conditions is required to enable farmers to decide the best planting time under various conditions within the existing land classification. The research to determine crop physiological response during the initial growth period was conducted in a greenhouse. This was combined with field treatments based on groundwater table depths at 15, 10 and 5 cm‐surface, respectively. Analysis of crop potential based on the water status conditions in the root zone was conducted by using secondary and primary data (daily records). Results of crop adaptation at shallow groundwater table depth showed that the treatments with groundwater table depth of 10 and 5 cm‐surface were not significantly different in terms of plant height, with a size of 12.6 and 12.3 cm, having three leaves. However, it had a significant effect on root length, with a length of 11.9 and 3.1 cm, respectively. Maximum plant height of 15.2 cm and four leaves were found for the treatment with a groundwater table depth of 15 cm‐surface. It may be concluded that it is best for farmers to plant at a groundwater table depth of 10 cm‐surface. © 2019 John Wiley & Sons, Ltd.

Relationship between root distribution characteristics of Mongolian pine and the soil water content and groundwater table in Horqin Sandy Land, China

Affected by soil moisture and groundwater table, Mongolian pine roots displayed an hourglass-type distribution characteristic, the high roots density distributed in the shallow and deep layers on sand soil. Mongolian pine (Pinussylvestris var.mongolica) is widely planted in arid and semiarid sandy land and serves as an important wind control and sand fixation species. In order to understand the effects of soil moisture and groundwater table on root distribution characteristics of Mongolian pine, we examined root distribution characteristics and determined the soil moisture and groundwater table under Mongolian pine plantations. The results indicated that the vertical distribution of Mongolian pine roots displayed an hourglass-type characteristic that indicated high density in the shallow (5–35 cm) and deep (85–145 cm) layers, but a low density in the middle layer (35–85 cm). Fine roots, which have a strong relationship with water utilization, displayed typical hourglass-type distribution characteristics. The proportion of fine roots in shallow soil layers (5–35 cm), middle layers (35–85 cm) and deep layers (85–145 cm) was 44.67%, 11.8% and 43.53%, respectively. Corresponding to root distribution characteristic, the shallow (0–40 cm) layer and the deep (90–150 cm) layer have a high soil water content than the middle layer. From May to October, the depth of groundwater table in the Mongolian pine plantation showed an increasing trend, from 185 to 291 cm, and the average groundwater table depth was 251 cm. The average height of capillary fringe above the groundwater table was 75.27 cm. Rainfall and groundwater have effects on the soil water content in a Mongolian pine plantation, and that determines the root distribution characteristics of Mongolian pine. The deep root system of Mongolian pine was effectively supplemented by groundwater, which is a necessary condition to maintain Mongolian pine survival and growth in the western Horqin Sandy Land.

Effect of natural conditions and mining activities on vegetation variations in arid and semiarid mining regions

Abstract Variation in vegetation can provide fundamental information about environment and resources management, especially in mining areas with vulnerable ecosystems. Research has demonstrated that vegetation patterns across river basins, plateaus, and mountains have been affected by climate change. However, variation in vegetation caused by natural conditions and mining activities in arid and semiarid mining areas is rarely examined. Using the Yushenfu mining area as a case study, based on the Sen + Mann–Kendall method, spatiotemporal characteristics of variation in vegetation were first analyzed using normal difference vegetation index (NDVI) time series data from 2006 to 2015. For comparison, a traditional linear regression method was applied to characterize NDVI trends, indicating the feasibility of the Sen + Mann–Kendall method. Subsequently, the effect of geomorphology, groundwater depth, and drought index on NDVI was assessed. The same geomorphology or groundwater depth did not correspond to a specific NDVI value, and a relationship between the drought index and NDVI was obtained. Then, unexploited areas and mined areas were compared, revealing that mining activities have a very obvious negative impact on vegetation ecology. Furthermore, the buried depth of the eco-safety groundwater table was determined to be 1.5–5.0 m based on the curve describing the relationship between groundwater depth and NDVI. This analysis produced an ecological sensitivity map with four key zones: primary, secondary, and tertiary sensitive areas and non-sensitive areas. These results provide a theoretical basis for developing fair and equitable outcomes for mineral resource development and environmental protection.

Exploration of the importance of physical properties of Indonesian peatlands to assess critical groundwater table depths, associated drought and fire hazard

Widespread degradation of Indonesian peatlands by deforestation and excessive drainage results into more frequent fires, particularly in El Niño years, which causes: (i) release of enormous amounts of peat soil carbon to the atmosphere, impacting climate, (ii) severe air pollution, affecting human health and air traffic, and (iii) decreased ecosystem services through loss of biodiversity. Groundwater table decline is the main driver of these negative processes and, therefore restoration of peatland hydrology is essential. Although groundwater table depth is critical to counteract peatland degradation, optimal depths are not generic for all peatlands, but depend on peat physical properties (i.e. water retention, unsaturated conductivity), which are related to the degree of peat humification (Fibric, Hemic, Sapric). Unfortunately only few of these peat physical properties are available while they are essential input data in hydrological models required to extend the usually short observed groundwater hydrographs. An experiment with the Soil-Water-Atmosphere-Plant model (SWAP) for two locations in Indonesian peatlands illustrates the impact of the degree of peat humification on physical properties and thereby on calculated groundwater table depth, hydrological drought and associated fires hazards. The Variable Threshold Method is applied to convert groundwater table depths into hydrological drought, and next the modified Keetch-Byram Drought Index (mKBDI) is used to assess wildfire hazard. Peat physical properties that reflect higher peat humification (Hemic and Sapric) result into lower water tables during dry periods, in particular during El Niño years, more severe hydrological drought, and an earlier and longer fire season. Using the limited available peat physical properties the importance is demonstrated of initiating a comprehensive programme to build a database of peat physical properties covering different environmental conditions in which tropical peatlands occur. Availability of such a database connected to a long-term monitoring programme, will support the ongoing rewetting, revegetation and revitalisation programme for Indonesian peatlands, which eventually will contribute to sustainable livelihoods for local people and reduce impact on the regional climate.

Evaluating Drainmod‐s to Predict Drainage Water Salinity and Groundwater Table Depth During Winter Cropping in Heavy‐Textured Paddy Soils

AbstractSimulation models can quickly and cost‐effectively describe various aspects of management practices in newly reclaimed agricultural soils. In this research, the capability of the DRAINMOD‐S model was evaluated to predict the salinity of the subsurface drainage effluents in a newly subsurface drained paddy field during winter cropping. Measurements of groundwater table depths and drainage water salinity were taken in three conventional subsurface drainage systems at the Sari Agricultural Sciences and Natural Resources University, northern Iran, during three canola growing seasons (2011–2012, 2015–2016 and 2016–2017). The data were used to calibrate and validate the model. The model provided better predictions of groundwater table depths in shallower drainage systems. Measured and simulated drainage water salinities varied, respectively, from 620 to 1580 and 790–1430 mg l−1 in the calibration process and from 441 to 1640 and 656–1820 mg l−1 in the validation process. The differences between measured and simulated salt loads were in the range of 59–174 and 43–586 kg ha−1 in calibration and validation, respectively. The results indicated that DRAINMOD‐S can be used as a management tool to diminish environmental issues in heavy paddy soils from the viewpoint of salt load. © 2019 John Wiley & Sons, Ltd.

Challenges and impacts of climate change and human activities on groundwater-dependent ecosystems in arid areas – A case study of the Nalenggele alluvial fan in NW China

Desert oases exist around the alluvial fans of inland river basins in arid areas, where the vegetation growth is wholly dependent on groundwater due to scanty rainfall and arid environment. Climate change and water resources exploitation may threaten the groundwater-dependent ecosystems (GDEs) in the arid areas; a case study was proposed to evaluate the vegetative growth state with the normalized difference vegetation index (NDVI), hydrometeorological data, and the exploitation of water resources of the Nalenggele alluvial fan in northwest China. Climate change, and increasing temperature and precipitation may be indispensable factors for vegetation growth; however, based on the results of a correlation analysis, it was found that climatic factors shared little direct correlation with the NDVIs of the Nalenggele alluvial fan. Also, the depth to groundwater table (DWT) and distribution of shallow groundwater (DSG) are the direct influencing factors of vegetation growth. DWT and DSG are mainly controlled by the groundwater recharge mechanism and the original water sources from snowmelt, which are directly correlated with climate change. Predictions for DWT and DSG were made considering water resource exploitation and different river discharges amid climate change. The results reveal that the distribution area of shallow groundwater with the ecological water level (DWT < 4 m) in 2020 will decrease to approximately 78–86% of that in the status quo year, which suggests vegetation may be at risk of degradation from the combined influence of climate change and human activities. Therefore, management strategy and legislation for protecting GDEs should be proactively initiated in other similar areas in China.

Quantitative analysis of the relationship between vegetation and groundwater buried depth: A case study of a coal mine district in Western China

Studying the interdependence between vegetation and the buried depth of groundwater is key to revealing the ecological and hydrological processes affecting vegetation in arid and semi-arid areas. The study area, the Yushen coal mine district, is located in the Mu Us Desert, which is the typical arid and semi-arid transition zone in Western China. There are a large number of areas with shallow with shallow groundwater depths in the region, which provides favorable growing conditions for vegetation growth. Due to sparse precipitation and rapid evaporation of water in the region, vegetative growth is tied closely to the depth of groundwater table. Given the widespread and intensive exploitation of the region’s abundant coal resources, the decline of groundwater table poses a threat to surface vegetation ecology health inevitably. Therefore, study of the ecological effects of large-scale changes to the depth of groundwater is of great significance for guiding exploitation of coal resources, eco-environmental conservation and future rehabilitation efforts. Using Yushen coal mine district as a study area, the quantitative relationship between groundwater buried depth and vegetation development is determined in different ecological and geological (eco-geological) environments by combining MODIS remote sensing with measured groundwater buried depth data as well as supplementing with other on-site investigations and collection of data. Using ArcGIS 10.5 and MATLAB R2018a, we divided the study area into 3 eco-geological environments: (1) phreatic water desert shallows oasis; (2) surface runoff (loess) gully; and (3) surface water river-valley oasis. The vegetation types, growth status, and diversity differed within the eco-geological environments. Based on the sensitivity of vegetation to the buried depth of groundwater in each of the three eco-geological environments, we further classified areas within the eco-geological environments as either type-1 sensitive, either type-2 sensitive or non-sensitive. We found that sensitivity class was related to the groundwater buried depth. Vegetative ecology improved with groundwater buried depth drawdown, while it deteriorated in type-2 sensitive areas. Vegetative ecology generally exhibited little dependence on groundwater buried depth in non-sensitive areas, where climate and soil moisture content were the predominant influences.

Evaluation of Moisture Damage under Crack-Sealed Asphalt Pavements in Louisiana

Crack sealing prevents the ingress of water in the pavement structure, thus preventing the weakening of the pavement and delaying its deterioration. Earlier studies indicate that sealing pavements in areas with a high ground water table (GWT) may prevent moisture from escaping upwards through cracks in asphalt pavements, therefore, accelerating stripping. The objective of this study was to provide guidelines for using crack sealing to minimize moisture entrapment under cracks, thus reducing stripping on low volume roadways. To achieve this, a calibrated Finite Element (FE) model was used to model a field experiment consisting of cracked and crack-sealed asphalt pavement sections. Sensitivity analysis was then conducted to compare crack-sealed and unsealed sections under different GWT levels, air relative humidity, air temperatures, rain intensities, and asphalt hydraulic conductivities. Results indicate that crack sealing could be applied under common rain intensities in Louisiana and any GWT depth without potential for stripping because of moisture entrapment if the hydraulic conductivity of the original pavement does not exceed 2 × 10–6 m/s. Yet, crack sealing should be applied after a dry period to ensure that the existing moisture in the original pavement is minimal. A non-linear regression model was developed for use in the Southern United States to help determine whether crack sealing should be used to avoid moisture damage in a cracked pavement at a given site based on the GWT and air relative humidity without the need for FE simulations. This can be a useful tool when planning maintenance activities.

Evaporation from seasonally frozen bare and vegetated ground at various groundwater table depths in the Ordos Basin, Northwest China

AbstractIn cold climates, the process of freezing–thawing significantly affects the ground surface heat balance and water balance. To better understand the mechanism of evaporation from seasonally frozen soils, we performed field experiments at different water table depths on vegetated and bare ground in a semiarid region in China. Soil moisture and temperature, air temperature, precipitation, and water table depths were measured over a 5‐month period (November 1, 2016, to March 14, 2017). The evaporation, which was calculated by a mass balance method, was high in the periods of thawing and low in the periods of freezing. Increased water table depth in the freezing period led to high soil moisture in the upper soil layer, whereas lower initial groundwater levels during freezing–thawing decreased the cumulative evaporation. The extent of evaporation from the bare ground was the same in summer as in winter. These results indicate that a noteworthy amount of evaporation from the bare ground is present during freezing–thawing. Finally, the roots of Salix psammophila could increase the soil temperature. This study presents an insight into the joint effects of soil moisture, temperature, ground vegetation, and water table depths on the evaporation from seasonally frozen soils. Furthermore, it also has important implications for water management in seasonally frozen areas.

Irrigation efficiency and shallow groundwater in anisotropic floodplain soils near Lake Tana, Ethiopia

AbstractField experiments were conducted (December 2014 to May 2015) in a small irrigation scheme (60 ha) to study the effect of flood irrigation on anisotropic soils with shallow groundwater in the Lake Tana floodplains of Ethiopia. Irrigation (470 ± 33 mm) was measured using V‐notches; rainfall did not occur, and the groundwater table was monitored daily using piezometers to estimate recharge from irrigated onion fields using the groundwater table fluctuation method. Recharge was influenced by applied irrigation amount, groundwater table depth, seasonal temperature variations, irrigation application efficiency and crop growth stages. The decreased deep percolation during the hottest periods and peak growth stages negatively influenced the reduction in groundwater decline caused by irrigation. The soil anisotropy also played a major role in the recharge amount: despite clay dominance in the topsoils, rapid groundwater table rises (0.02–0.56 m) were due to the presence of granular and blocky structures. Recharge was also influenced by irrigation efficiency, indicating higher recharge during periods of lower efficiency. The seasonal recharge was 34–46% of applied irrigation and there is much room for improving irrigation efficiency which is only 46 (±12) to 51 (±17)%. © 2019 John Wiley &amp; Sons, Ltd.

Five-Year Experimental Study on Effectiveness and Sustainability of a Dry Drainage System for Controlling Soil Salinity

The dry drainage system (DDS) is an alternative technique for controlling salinization. To quantify its role in soil salinity control, a five-year field observation from 2007 to 2011 was completed in a 2900 ha experimental plot in Yonglian Experimental Station, Hetao Irrigation District, China. Results showed that the groundwater table depth in the fallow areas quickly responded to the lateral recharge from the surrounding croplands during irrigation events. The groundwater electrical conductivity (GEC) of fallow areas increased from 5 mS·cm−1 to 15 mS·cm−1, whereas the GEC below croplands produced small fluctuations. The analysis of water and salt balance showed that the excess water that moved to fallow was roughly four times that moved by an artificial drainage system and with 7.7 times the corresponding salt. The fallow areas act as a drainage repository to receive excess water and salt from surrounding irrigated croplands. Slight salt accumulation occurred in irrigated croplands and salts accumulated, with an accelerating trend over the final two years. The evaporation capability weakened, partly due to the salt crust in the topsoil, and the decrease in soil permeability in the soil column, which was almost impermeable to water. Using halophytes may be an effective method to remove salts that have accumulated in fallow areas, having great economic and ecological value. A DDS may be effective and sustainable in situations where the fallow areas can sustain an upward capillary flux from planted halophytes.

The Effect of Geological Heterogeneity and Groundwater Table Depth on the Hydraulic Performance of Stormwater Infiltration Facilities

Urbanization has led to a substantial change in the hydrological cycle of urban catchments. Increased runoff and urban flooding, decreased direct subsurface infiltration and groundwater recharge, deterioration of water quality are among the major effects of this alteration. To alleviate these effects, Low Impact Development (LID) practices have been frequently adopted for stormwater management. Among LID infrastructures, infiltration facilities are particularly challenging to design and model due to the considerable amount of uncertainties related to the hydrogeological configuration of installation sites. To date, analysis on how soil heterogeneity, groundwater table depth, and thickness of the unsaturated zone affect the hydraulic performance of infiltration facilities are lacking. To address this knowledge gap, a series of numerical experiments under transient variably water saturated conditions were performed for a hypothetical infiltration facility. Numerical simulations showed that i) infiltration rates increase considerably as the initial depth of the groundwater table increases, ii) the contribution of the bottom of the facility to the infiltration of water is generally higher than the sides, iii) the presence of a less conducting soil layer at a short depth from the bottom of the facility reduces infiltration rates dramatically, iv) the complete clogging of the bottom of the facility has a dramatic impact on the hydraulic performance, v) the stochastic heterogeneity of the soil controls the overall stormwater infiltration process through the facility, and the hydraulic performance may largely deviate from the case when heterogeneity is absent.

Simulation of Soil Freezing and Thawing for Different Groundwater Table Depths

Core Ideas The SHAW model was used to simulate the freeze–thaw process during freeze–thaw periods. It revealed the effects of soil texture and groundwater table depth on soil freezing and thawing. The frost depth and accumulated negative soil surface temperature relationship was determined. During freeze–thaw periods, the transformation between phreatic water and soil water will change the soil hydrothermal properties and affect the soil freezing and thawing in shallow groundwater areas. The purpose of this study was to determine the effect of four different groundwater table depths (GTDs) and two soil textures on the process of soil freezing and thawing during two successive freeze–thaw periods using the Simultaneous Heat and Water (SHAW) model. The results show that the frost depth was the maximum when the GTD was 1.0 m, and the maximum frost depths of sandy loam and fine sand were 97.6 and 98.9 cm, respectively. When the GTD was larger than 1.5 m, the maximum frost depth decreased with an increase in GTD, and the maximum frost depth of the soil profile was more sensitive to changes in the air temperature. The frost depth of the soil profile was linear with the square root of the accumulated negative soil surface temperature (ANST) under different GTDs. The ANST was influenced by the phreatic evaporation, and the soil freezing rate increased with an increase in GTD under the same ANST. This research is significant for the rational development of soil water and heat resources and the study of soil water–heat transfer in shallow groundwater areas.

GIS and Remote sensing Approach in Identifying Ground Water Recharge Zones of Cheriyal Watershed

India has been bestowed with substantial water resources. Ground water, which is the source of more than 85 percent of rural domestic water requirements of the country, is depleting fast in many areas due to its large-scale withdrawal. Present study was conducted in a watershed to identify the ground water recharge zones and suitable structures using Remote Sensing coupled with Geographical Information System and Analytical Hierarchy Process. The parameters such as Geology, Geomorphology, Soil type, Land use, Lineament, Elevation, Slope and Ground water table depth were selected that are closely linked to surface and ground water availability. A base map of watershed was prepared by digitizing the boundary in bhuvan. The satellite images DEM 30 m, LISSIII 25 m and field inputs were used to derive different thematic maps. Multi criteria decision making was applied to all the parameters in thematic maps by assigning ranks from 1 to 5 scale and reclassified depending on its influence on the storage and movement of groundwater. The pair wise comparison for 6 layers were given based on the comparison between the layers and their relative importance towards groundwater prospects and a 6×6 matrix was formed. Based on the comparison matrix the reclassified maps were multiplied with normalized weights and added up in raster calculator to get the final suitability map. From the analysis it was found that 5.70 Percent area is highly suitable for recharge and 60.58 Percent of area was moderately suitable and 33.71 Percent was less suitable for recharge.

Response characteristics of photosynthesis and sap flow parameters in Tamarix chinensis leaves to depth of groundwater table in the Yellow River Delta

Response characteristics of photosynthesis and sap flow parameters in Tamarix chinensis leaves to depth of groundwater table in the Yellow River Delta

Study on Technology of Surface Pre-grouting for Vertical Shaft in Broken and Water-rich Granite Strata of Gaoligong Mountain Tunnel of Dali-Ruili Railway

The Gaoligong Mountain Tunnel of Dali-Ruili Railway is located between the Nujiang River and the Longling County Town in the southeastern section of the Hengduan Mountains, China. In geological history, this area was affected by multiple tectonic movements, and the faulted structures are extremely developed. During the drilling inspection hole of No.2 vertical shaft, boring tool stuck and the hole collapse once happened. Its depth was 643.12 m, the outcropped strata were all granite or weathered granite (fracture zones). 7 fracture zones with thickness > 10 m were uncovered, the maximum thickness of which was 112.95 m; and 7 water bearing strata were uncovered, of which the buried depth of groundwater table was all less than 34m, the permeability coefficients(k) were 0.005∼0.158 m/d. It was estimated that the water inflow of ④ ∼ ⑦ aquifers of the main shaft and the auxiliary shaft of No. 2 shaft were all greater than 120 m3/d (5 m3/h), that normal water inflow of main shaft and auxiliary shaft of No.2 vertical shaft would be 125.92 m3/h and 90.08 m3/h respectively. In order to avoid water inrush and wall caving accidents during the construction of the two shafts, it was decided to adopt the surface pre-grouting method in the construction of the shafts to block off and reinforce the ④ aquifer and the strata under the aquifer. The “S” shaped directional drilling technology was used; the two sequences, segmented downward, multiple-times grouting mode was adopted; clay-cement slurry was selected as the grouting material. After grouting, pump yield water tests were carried out in two grouting holes of main shaft and auxiliary shaft. The remaining water inflow in grouting sections of two shafts was 5.02 m3/h and 5.70 m3/h respectively, and the rates of water blocking were all over 93%. The grouting effect was remarkable. The successful implementation of the surface pre-grouting project of No.2 vertical shaft in Gaoligong Mountain Tunnel of Dali-Ruili Railway has important guiding significance for the design and construction of tunnel and mine shafts in broken water-rich granite stratum.

Interpretation of soil quality indicators for land suitability assessment – A multivariate approach for Central European arable soils

Soils and their functions are critical to ensuring the provision of various ecosystem services. Many authors nevertheless argue that there is a lack of satisfactory operational methods for quantifying the contributions of soils to the supply of ecosystem services. Therefore, it is difficult to automate and standardize the mathematical and statistical methods for the selection of indicators and their scoring. Our objective is the development of a novel soil quality and ecological indicator selection and scoring method based on a database representing the most common Hungarian soils typical for arable lands of Central Europe (Chernozems, Phaeozems, Luvisols, Cambisols, Gleysols, Solonetz, Arenosols). For evaluation purposes, soil texture, depth to groundwater table, soil organic matter (SOM), pH, calcium carbonate equivalent (CCE), electrical conductivity (EC), Na, available N, P, K, Mg, S, Cu, Zn and Mn of 1045 plots representing a total land area of about 5000 ha at 0–30 cm layer were analyzed. We classified the samples into 25 soil types. Using correlation, principal component analysis and discriminant analysis the direction and strength of the intercorrelation of indicators and their combinations were determined. Indicators were classified into the following categories: (1) indicators that characterize nutrient retention and cation exchange capacity: texture, SOM, EC and Na; (2) available nutrients, relatively independent from management practices: K, Mg, Cu; (3) indicators that determine base saturation: pH, CCE, available Mn; (4) highly variable available nutrients: N, S, P, Zn. By reviewing the results of Hungarian long-term experiments, we interpreted the soil indicators as a function of agricultural suitability. Following the parameterized and non-linear interpretation of the indicators, we analysed the variance of soils, in terms of their agricultural land suitability. According to the intercorrelation of input indicators and variance of scored indicators the minimum data set for soil quality assessment includes texture, depth of groundwater table, SOM, pH, Na, available K, P and Zn. In order to further advance our soil quality assessment model, our following goals target the determination the hierarchical ranking and grouping of soil parameters in a combined manner.