Water Table Level Research Articles

The carbon dioxide fluxes at the open-top chambers experiment on the ombrotrophic bog (Mukhrino field station)

The continuous measurement of CO2 fluxes at the open-top chamber experiment in the ombrotrophic peatland (located in the middle taiga zone, West Siberia, Russia) has been provided during the warm season of 2022 (beginning of June to beginning of October). The Reco, NEE and GPP were calculated for this period; abiotic factors related to CO2 emissions, such as PAR, air temperature, water table level and precipitation, were also measured. The monthly average values showed a negative NEE of -9.89 C g m-2 month-1 in July, a negative GPP of -34.19 C g m-2 month-1 in July, and a positive values Reco of 41.68 C g m-2 month-1 in August. In 2022, the studied peatland hollows were only a carbon stock in July, while in the remaining months they were a source of CO2, which could be caused by small precipitation amount.
 The monthly average diurnal variations of CO2 fluxes showed similar behaviour for both the OTC plot and control plot fluxes, which may be explained by the similarity in vegetation cover.

Using Spectral Indices Derived from Remote Sensing Imagery to Represent Arthropod Biodiversity Gradients in a European Sphagnum Peat Bog

Monitoring of peatlands is an important conservation issue. We investigated communities of soil mites (Acari: Oribatida, Mesostigmata) inhabiting a relatively undisturbed European boreal mire characterized by a mosaic of oligotrophic and meso-eutrophic areas. We assess the potential of using remote sensing approach as a mapping and predictive tool for monitoring productivity and arthropod biodiversity in a peat bog. In georeferenced plots, Acari biodiversity, water table level, water pH and plot productivity class on the oligotrophic-eutrophic gradient were recorded. Data from the Landsat 8 OLI sensor were used to calculate several spectral indices known to represent productivity and surface moisture gradients in terrestrial ecosystems. We then explored the relationship between spectral indices, environmental gradients and biodiversity of mites. We found that several spectral indices were significantly and consistently correlated with local environmental variables and biodiversity of soil mites. The Excess Green Index performed best as a predictor of plot trophic class on the oligotrophic-eutrophic gradient and showed significant relationship with Oribatida diversity in 2016. However, following hot summer in 2019, there was no significant relationship between abundance and species richness of Oribatida and remotely sensed data; there was a weak correlation between abundance of Mesostigmata and spectral indices which represent surface moisture gradient (e.g., Normalised Difference Moisture Index). We discuss advantages and challenges of using spectral indices derived from remote sensing imagery to map biodiversity gradients in a peatland.

Electron Accepting Capacities of a Wide Variety of Peat Materials From Around the Globe Similarly Explain CO2 and CH4 Formation

AbstractIn organic soils, the availability of terminal electron acceptors (TEAs) determines the ratio of CO2 to CH4 formation under anoxic conditions. While the importance of electron accepting capacities (EACs) of organic matter is increasingly acknowledged, redox properties of organic matter have only been investigated in a limited set of peat and reference materials. Therefore, we incubated 60 peat samples from 15 sites covering a variety of both bog and poor to intermediate fen samples and characterized their capacities to serve as TEA for anaerobic CO2 formation. We quantified CO2 and CH4 formation and changes in available EAC in anoxic incubations of 56 days. In our experiment, on average 36.5% of CO2 could be attributed to CH4 formation, assuming an CO2:CH4 ratio for methanogenesis of 1:1. Regarding the remaining CO2 formed, for which a corresponding TEA would be needed, we could on average explain 70.8% by corresponding consumption of EAC from both organic and inorganic TEAs, the latter contributing less than 0.1%. When the initial EAC was high, CO2 formation from the apparent consumption of EAC was high and outweighed CO2 formation from methanogenesis. Rapid depletion of available EAC, especially in reactive peat, resulted in a higher share of CO2 from CH4 formation. Our study demonstrates that EAC provides the most important redox buffer for competitive suppression of methanogenesis in peat soils, particularly under fluctuating water table levels, when EAC is repeatedly regenerated. Moreover, electron budgets including EAC of organic matter could largely explain anaerobic CO2 production.

Spatiotemporal Analysis of Groundwater Resources in the Saïss Aquifer, Morocco

In recent decades, the Saïss plain, in the northwest of Morocco, has experienced a noticeable increase in water demand due to a very significant population growth and economic development, as well as the climate change effects. With the aim of reaching optimal and dynamic management of these water resources, it is essential to have comprehensive and reliable information on the state of the aquifer systems in the region. To achieve this, we assessed a geostatistical analysis of groundwater level data, and created a multivariate regression model. Indeed, in this study, a spatiotemporal analysis of groundwater depth based on piezometric measurements of 45 wells was carried out for the period from 2005 to 2020. It compares and evaluates eight geostatistical interpolation methods and solves the problem of data gaps of the piezometric measurement by completing the chronological series of the groundwater level between 2005 and 2020 using the ARIMA model. The results demonstrate that the variation in the groundwater level between 2005 and 2020 indicates that the water table level is decreased in certain areas, but it has improved or remained constant in other areas. These results emphasize an urgent need for a dynamic management for the conservation of groundwater resources in certain areas of the region under this study.

Delineation of Ground Water Recharge Potential Zones in Lahore District, Punjab, Using Remote Sensing and GIS Techniques

Lahore is the provincial capital of Punjab and the second most populous city in Pakistan. Aquifer rechargerates have been continuously decreasing over a long period of time, which has caused a significant decline in the watertable level. Rapid population growth, urban development, and industrialization have all raised the demand for watersupplies. Due to significant infrastructural development, a considerable portion of the land is now impervious andrainfall now drains as surface runoff rather than recharging the aquifer level. Average annual rainfall, one of theprimary sources used to replenish the Lahore aquifer, is insufficient to prevent the depletion of the water table, andRiver Ravi stays almost dry except in rainy seasons. Geographic information system (GIS) and remote sensing (RS)techniques are used to find suitable areas for replenishment in the Lahore aquifer system in order to enhancesustainability and prevent decreasing groundwater levels. Distance from the water channel, land use/land cover(LULC), slope, geology, drainage density, rainfall, lineament density, and soil type are the eight layers that have beenintegrated with the GIS overlay analysis. Thematic maps are generated using both conventional and remote sensingdata. These maps are eventually converted to raster data. Very good, good, moderate, poor, and very poor are the fivezones that have been delineated. A good to very good

Water table dynamics of dune slacks in an arid zone

In this study, a characterisation is undertaken of the humid dune slacks water table situated in the arid transgressive coastal dune field of the Maspalomas Special Area of Conservation, ES701007 (Gran Canaria, Canary Islands, Spain). Humid dune slacks are listed as a European Union Habitat (EU Habitat 2190 humid dune slacks) in Annex I of the EU Habitats Directive. This water table is relatively stable throughout the year, with a 41 cm maximum oscillation. The annual dynamics of the flow pattern and water table level depend on the climate conditions. At the end of the hydrological dry season the mean water table drops (ca. 11 cm) and water flows to the lagoon. After rains, the mean water table level rises (ca. 4 cm) and flows towards the Maspalomas beach. The distribution of plant communities (associated to EU Habitat 2190) in the Maspalomas humid dune slacks depends on water table depth, pH and salinity. The knowledge acquired in this study of the water table dynamics has enabled a better understanding of the spatial distribution patterns of the vegetation of these slacks, in particular with respect to the relationship between the water table flux toward the coast during the dry season and the distribution of plant communities in the slacks closest to the coast. The study of the dynamics of the water table of the slacks and the associated vegetation has allowed us to better understand the characteristics of the Maspalomas humid dune slacks and potentially improve their management as EU Habitat. This is especially significant considering that the only European arid climate dune field where this habitat can be found is in Maspalomas.

EARLY EFFECTS OF THE LATE PALEOZOIC CLIMATE TRANSITION ON SOIL ECOSYSTEMS OF THE APPALACHIAN BASIN (CONEMAUGH, MONONGAHELA, AND DUNKARD GROUPS): EVIDENCE FROM ICHNOFOSSILS

ABSTRACT The late Paleozoic transition is well represented by the upper Pennsylvanian to lower Permian Conemaugh, Monongahela, and Dunkard groups of the western Appalachian Basin (U.S.A.). These units contain abundant paleosols possessing suites of ichnofossils that serve as indicators of soil moisture, soil organic content, water table level, precipitation, and landscape stability. Analysis of these units can, therefore, be used to refine the details of how late Paleozoic terrestrial landscapes changed through time. A study along a 50 km west-east and a 40 km north-south transect through southeast Ohio and southwest West Virginia resulted in the recognition of 24 pedotypes with distinct ichnofossil assemblages. Ichnofossils include rhizoliths, Planolites, Palaeophycus, Taenidium, Scoyenia, Macanopsis, Skolithos, Cylindricum, cf. Psilonichnus, Arenicolites, mottles, and coprolites produced by various plants, gastropods, and larval-to-adult soil arthropods. Soil-forming environments include palustrine, levee, proximal to distal floodplain, interfluve, backswamp, marsh, and fen settings. An up-section shift in pedotypes from Argillisols to Vertisols and Calcisols as well as an overall increase in the diversity of pedotypes recorded a change in soil-forming conditions, resulting in a diverse landscape that changed significantly as mean annual precipitation rose and fell. An up-section increase in ichnofossil diversity in the paleosols and changes in ichnocoenoses suggests an increased dependence on the soil as a refuge and as a food resource. Overall, growing instability of the climate during the Pennsylvanian–Permian transition led to a more heterogeneous landscape that helped to promote colonization of a more diverse assemblage of soil organisms.

RETRACTED: Delineation of potential managed aquifer recharge sites of Kuchlak sub-basin, Balochistan, using remote sensing and GIS

In the Kuchlak Sub-Basin (Pakistan), groundwater is overexploited, resulting in growing stress on groundwater resources. The water table level has declined rapidly due to intensive pumping. Artificial recharge methods and good management strategies are vital for the sustainable production of groundwater resources. Managed aquifer recharge is an artificial way of recharging the subsurface aquifers using surplus surface water, treated wastewater, and stormwater. It is a potential strategy for increasing freshwater supply and adapting to climate change. The present study proposes a method to delineate potential zones for MAR suitability in the Kuchlak Sub-Basin. INOWAS, a web-based tool, is utilized for narrowing down the available MAR techniques based on the hydrogeologic parameter and objectives of the study area. A geographic information system (GIS) coupled with the multi-criteria decision analysis (MCDA), commonly known as GIS-MCDA, is used to develop the MAR suitability map. Six criterion maps, including geology, land use, slope analysis, drainage density, soil, and rainfall, were created in ArcGIS for suitability mapping. The criterion maps are ranked and weighted based on their relative contribution to the groundwater recharge and published literature using the Multi Influence Factor (MIF) method. The final suitability map was developed by overlaying all the criterion maps using a weighted linear combination (WLC) technique. The MAR suitability map was divided into five zones, namely, very high, high, moderate, very low, and low. The unsuitable zones reflect the urban and slope constraints that reduce surface infiltration. The suitability map reveals that 45% of the Kuchlak Sub-Basin exists in a very high-high suitability zone, 33% in moderate, and 17% in a very low-low suitability zone, while 5% of the study area was unsuitable due to the urban and slope constraints. The MAR suitability map developed in this study can serve as a basis for conducting a focused analysis of MAR implementation. Furthermore, the technique and results of this study may aid in mapping MAR suitability in any arid or semi-arid region.

Response of soil respiration to changes in soil temperature and water table level in drained and restored peatlands of the southeastern United States

BackgroundExtensive drainage of peatlands in the southeastern United States coastal plain for the purposes of agriculture and timber harvesting has led to large releases of soil carbon as carbon dioxide (CO2) due to enhanced peat decomposition. Growth in mechanisms that provide financial incentives for reducing emissions from land use and land-use change could increase funding for hydrological restoration that reduces peat CO2 emissions from these ecosystems. Measuring soil respiration and physical drivers across a range of site characteristics and land use histories is valuable for understanding how CO2 emissions from peat decomposition may respond to raising water table levels. We combined measurements of total soil respiration, depth to water table from soil surface, and soil temperature from drained and restored peatlands at three locations in eastern North Carolina and one location in southeastern Virginia to investigate relationships among total soil respiration and physical drivers, and to develop models relating total soil respiration to parameters that can be easily measured and monitored in the field.ResultsTotal soil respiration increased with deeper water tables and warmer soil temperatures in both drained and hydrologically restored peatlands. Variation in soil respiration was more strongly linked to soil temperature at drained (R2 = 0.57, p < 0.0001) than restored sites (R2 = 0.28, p < 0.0001).ConclusionsThe results suggest that drainage amplifies the impact of warming temperatures on peat decomposition. Proxy measurements for estimation of CO2 emissions from peat decomposition represent a considerable cost reduction compared to direct soil flux measurements for land managers contemplating the potential climate impact of restoring drained peatland sites. Research can help to increase understanding of factors influencing variation in soil respiration in addition to physical variables such as depth to water table and soil temperature.

Effects of water table level and nitrogen deposition on methane and nitrous oxide emissions in an alpine peatland

Abstract. Alpine peatlands are recognized as a major natural contributor to the budgets of atmospheric methane (CH4) but as a weak nitrous oxide (N2O) source. Anthropogenic activities and climate change have put these fragile nitrogen (N)-limited peatlands under pressure by altering water table (WT) levels and enhancing N deposition. The response of greenhouse gas (GHG) emissions from these peatlands to these changes is uncertain. To address this knowledge gap, we conducted a mesocosm experiment in 2018 and 2019 investigating individual and interactive effects of three WT levels (WT−30, 30 cm below soil surface; WT0, 0 cm at the soil surface; WT10, 10 cm above soil surface) and multiple levels of N deposition (0, 20, 40, 80 and 160 kgNha-1yr-1) on growing season CH4 and N2O emissions in the Zoige alpine peatland, Qinghai–Tibetan Plateau. We found that the elevated WT levels increased CH4 emissions, while N deposition had nonlinear effects (with stimulation at moderate levels but inhibition at higher levels). In contrast no clear pattern of the effect of WT levels on the cumulative N2O emissions was evident, while N deposition led to a consistent and linear increase (emission factor: 2.3 %–2.8 %), and this was dependent on the WT levels. Given the current N deposition in the Zoige alpine peatland (1.08–17.81 kg N ha−1), our results suggested that the CH4 and N2O emissions from the alpine peatlands could greatly increase in response to the possible doubling N deposition in the future. We believe that our results provide insights into how interactions between climate change and human disturbance will alter CH4 and N2O emissions from this globally important habitat.

Base-level poljes in the Sivas gypsum karst, Türkiye

The Sivas Basin, Central Anatolia, includes one of the most outstanding gypsum karst terrains in the world, covering an area of 2140 km2. The karst landscapes are developed on late Eocene gypsum deposits. The fact that the polje shapes that are commonly seen in the limestone karst terrain also seen in the Sivas gypsum karst area further increases the importance of this area in terms of geomorphology. This study is focused on the explanation of the morphometric properties and formation mechanism of poljes around the Kızılırmak River in the Sivas gypsum karst area. The geomorphological evolution of the Sivas gypsum karst area was controlled by the Kızılırmak River drainage system formed in the Early Pliocene. Polygonal doline karst is common on the High Karst Plateau (or erosional-denudational surface) formed during this evolution process, while subsidence dolines, hanging valleys, and poljes are common on the Low Karst Plateau. A total of 14 poljes, most of which are drained underground, and a corrosion plain were identified around the Kızılırmak River in the Low Karst Plateau. The boundaries of some of the poljes, the area of the largest of which is 6.3 km2, and hence their strike is controlled by faults. These poljes are base-level poljes, which bases are approximately at the river level and developed in the water table fluctuation zone. In addition to the structural lines in the formation of the poljes, the beginning of a blind valley-like karstification process, especially in the lower parts of the hanging valleys, mostly as a result of the collapse doline formation (showing the estevalle feature), changes in the water table level in the epiphreatic zone, and in addition to the precipitation, the aggressive river floodwaters that invaded the polje floor were effective. Due to the rapid dissolution of gypsum, the development of polje must have been affected by the incision and deposition periods of the river. The Tödürge Lake depression most probably has been shaped by collapse dolines.

Fine-root biomass production and its contribution to organic matter accumulation in sedge fens under changing climate

Climate change may affect the carbon sink function of peatlands through warming and drying. Fine-root biomass production (FRBP) of sedge fens, a widespread peatland habitat, is important in this context, since most of the biomass is below ground in these ecosystems.We examined the response of fine-root biomass production, depth distribution (10 cm intervals down to 60 cm), chemical characteristics, and decomposition along with other main litter types (sedge leaves, Sphagnum moss shoots) to an average May-to-October warming of 1.7 °C above ambient daily mean temperature and drying of 2–8 cm below ambient soil water-table level (WL) in two sedge fens situated in Northern and Southern Boreal zones. Warming was induced with open top chambers and drying with shallow ditching. Finally, we simulated short-term organic matter (OM) accumulation using net primary production and mass loss data.Total FRBP, and FRBP in deeper layers, was clearly higher in southern than northern fen. Drying significantly increased, and warming marginally increased, total FRBP, while warming significantly increased, and drying marginally increased, the proportional share of FRBP in deeper layers. Drying, especially, modified root chemistry as the relative proportions of fats, wax, lipids, lignin and other aromatics increased while the proportion of polysaccharides decreased. Warming did not affect the decomposition of any litter types, while drying reduced the decomposition of sedge leaf litter. Although drying increased OM accumulation from root litter at both fens, total OM accumulation decreased at the southern fen, while the northern fen with overall lower values showed no such pattern.Our results suggest that in warmer and/or modestly drier conditions, sedge fen FRBP will increase and/or be allocated to deeper soil layers. These changes along with the altered litter inputs may sustain the soil carbon sink function through OM accumulation, unless the WL falls below a tipping point.

A decrease in the water table levels in kaduna North and an increase in the water table levels in kaduna South.

A decrease in the water table levels in kaduna North and an increase in the water table levels in kaduna South.

Geomorphological controls on the evolution of a new streamflow in the piedmont of the southern of Sierras Pampeanas: A case study of the Río Nuevo, West-central Argentina

Our understanding of the geomorphological processes that drive river formation and hydrological settings that favour them is still under development, facing the difficulties of knowledge fragmentation and the mismatch of temporal scales, particularly in arid or semi-arid regions. In this study, we provided new evidence on the link between river formation and hydrological settings by analysing the extremely rapid development of a new river (Rio Nuevo) network in the Morro basin, San Luis, West-Central Argentina. The geomorphology and the morphoevolution of the new hydrographic basin were documented in view of its morpho-litho-stratigraphy and structural characteristics of the river valley. Six main geomorphological units in relation with the formation of the new river were identified. Three of these units predated such formation, two other geomorphological units accompanied the onset of river formation and were also subject to rapid expansion while the last one (lagoons and wetlands) is still stable due to the river rapid expansion as a result of water table level rise. The evaluation of these geomorphological characteristics has provided a better understanding of the process that governs the formation of rivers in semiarid areas, contributing to the prediction and management of future transformations. Further geomorphological controls associated with topographic configuration and tectonic processes were also inferred.

Detection of Groundwater Pathways to Monitor Their Level Rise in Osirion at Abydos Archaeological Site for Reducing Deterioration Hazards, Sohag, Egypt Using Electrical Resistivity Tomography Technique

Climatic changes because of groundwater levels rising near the archaeological sites became a fundamental issue in Egypt. The problem will affect the deterioration of the stone foundations of the temples and any archaeological features, which will affect their deformation, changing their features, and their archaeological and architectural importance. Osirion in Abydos archaeological place, west of Sohag Governorate, undergoes this problem where the level of ground water increases west of this site in the spring season. Solving this problem will help to preserve the antiques at the Abydos site and, in particular, the Osirion and its surrounding area. It is important to understand the hydrostratigraphic conditions of the Abydos site and its surroundings. The main objectives of the work are: (1) characterizing the subsurface succession and lithology; (2) identifying the sources responsible for the groundwater level rising near the Osirion, and groundwater assessment distribution and water table depth; and (3) evaluating the subsurface location and geometry of any paleochannels that may represent conduits for groundwater flow pathways to join the water to the studied site. All this information will aid the officials to decide and make future solutions to solve these problems. To achieve these goals, the authors implemented an advanced geophysical technique, namely electrical resistivity tomography (ERT) investigations in conjunction with the existing boreholes data. The main outcomes of this work are 2D and 3D representations of the resistivity distributions, which reflect a full picture about the subsurface engineering layers, including details of the lithology of the study site. The subsurface succession includes four geoelectrical zones that were recognized. The water table level in the study site varies from 5 m to 14 m as confirmed from all the ERT profiles together with the available borehole data. A three-dimensional visual representation of the water-bearing muddy sand formation shows the presence of a potential channel in the north-east direction and its location, which is responsible for delivering the groundwater from the Nile River to the Osirion site. This result is in consistent with archaeological studies conducted in the Osirion site, where there are ancient archaeological text and drawings on the temple walls and columns. By defining the direction of the groundwater pathways, the authors recommend the decision-makers to take the engineering precautions to try to prevent the groundwater from reaching the important archaeological sites by establishing the dams and partitions. In addition, they should monitor and control the groundwater level changes around the archaeological foundations by implementing all the necessary measurements to prevent the soil subsidence and foundation collapse, and establishing a dewatering system network.

Geochemistry of decades-old spodumene mine tailings under a humid continental climate

Transports electrification efforts currently increase global demand for lithium, but literature about the environmental geochemistry of spodumene mine tailings is very scarce. Mine tailings from the former Québec Lithium Corporation site in La Corne, Québec, Canada, were submitted to a suite of geochemical and mineralogical characterizations to evaluate metals distribution and mobility 55 years after deposition. From 1955 to 1965, production of spodumene concentrate, lithium carbonate and other lithium salts from a spodumene-pegmatite ore left behind about 750,000 tons of non-sulfidic tailings (mostly from flotation). Core samples of the tailings were collected from 5 boreholes ranging from 5.13 to 9.75 m in depth. Results show that grain size and metals distribution is heterogeneous, with elements groups (Li–Ta–U or K–Rb) being enriched or depleted in coincident strata and zones. The mineralogical assemblage is dominated by quartz, albite and other feldspars, unrecovered spodumene (up to 12 wt%), and micas, displaying few to no signs of weathering. Sequential extraction results indicate that for most elements surveyed, including Li and Be, secondary retention mechanisms like precipitation, sorption, and ion exchange, almost exert no control on their mobility within the tailings. Silicate-hosted elements (Al, Li, Be, K, Rb) were proportionally among the least extractable. The most extractable elements are either ubiquitous in the environment (Fe, Mn) or hosted in metamict minerals (U). Apart from paste pH which tends to be relatively lower close to the surface, no relation is evident between depth or the water table level and any physical or geochemical parameter. Despite the tailings being almost unweathered, the surrounding waters contain Li concentrations up to the mg/L range. This study gives environmentally-relevant insights into the geochemistry of non-sulfidic spodumene-pegmatite mine tailings as surging worldwide demand for Li attracts interest towards new spodumene mining projects.

Monitoring the Dynamics of Ephemeral Rivers from Space: An Example of the Kuiseb River in Namibia

Ephemeral rivers are characterized by brief episodic flood events, which recharge subterraean alluvial aquifers that sustain humans, riparian vegetation, and wildlife in the hyper-arid Namib Desert. Yet we only have a poor understanding of the dynamics and feedback mechanisms in these hydrological systems as arid and semi-arid zones are typically poorly equipped with reliable in situ monitoring stations to provide necessary information. The main objective of our study is to show the potential of satellite data to monitor the dynamics of ephemeral rivers, such as the Kuiseb located in Namibia, since remotesensing offers the advantage of adapted spatial and temporal resolutions. For this study, multi-spectral imagery (Sentinel-2), Synthetic Aperture Radar (SAR, Sentinel-1), and SAR interferometry (Sentinel-1) data were used to produce Normalized Difference Vegetation Index (NDVI) maps, backscattering maps (as σ0), and interferograms, respectively. These parameters provide information on the hydrologic and vegetation dynamics of the river. Strong variations in NDVI, σ0, and interferograms are observed during March–April 2017 and June–July 2018 in a tributary of the Kuiseb in the central Namib Desert. In those years, rain events caused the reactivation of the tributary. However, during a major flood in 2021, when no rain occured, no variations in NDVI were detected in this tributary, unlike the σ0 and interferogram anomalies after the flood. Thus, these variations cannot be explained by rains, which were non-existent during this period, but seem to be linked to the dynamics of the aquifer of the Kuiseb River, wherein floods recharge the alluvial aquifers and the rising water table levels produce a signal that is measurable by satellite radar sensors. All these results present a preliminary work that might be used by water resource managers to automate the processing and methods used to create an ephemeral river monitoring tool.

Foundation systems for sustainable revitalisation of spoil dump areas

The design of foundations systems is well established in the literature and codes of practice. However, these are generally applicable to well characterised, homogenous ground conditions. Spoil materials represent a significant challenge when implementing these design procedures due to their time-dependent characteristics, their spatial variability , and the likelihood that they will consist of low strength/stiffness materials. As such, careful consideration is required when designing foundation systems on spoil materials, especially for sensitive structures such as wind turbines. Physical modelling experiments using a geotechnical centrifuge were conducted to study the spoil-foundation system interaction. In these tests, an equivalent spoil was used that provided satisfactory reproduction of key physical and mechanical characteristics of a real spoil material. Three types of foundation systems were considered in the centrifuge tests: (1) raft foundation, (2) pile-group foundation, and (3) pile-raft foundation. The long-term cyclic loading of 87kN, 171kN and 460kN maximum cyclic load were used for the raft foundation. A higher cyclic load of 501kN was applied to the pile-group and pile-raft foundations. To evaluate the effect of climatic condition variations on spoil-foundation interactions, the centrifuge tests were carried out at different water table levels within the spoil material. The experimental results were analysed in terms of foundation rotation and foundation vertical settlement. The raft foundation rotated around 0.1-0.2 degrees and vertically displaced by 5-10 mm, whereas the pile-group rotated about 0.6-0.8 degrees and vertically displaced by 20-30 mm due to long-term cyclic loading. The pile-raft foundation displayed better response as compared to pile-group foundation.

Climate impact assessment to the groundwater levels based on long time-series analysis in a paddy field area (Piedmont region, NW Italy): preliminary results

The analysis of the time-series of groundwater level are extremely important to observe the behaviours of groundwater over time and to identify any critical situations. The studied area is an agricultural district characterised by paddy fields, located in the eastern part of Piedmont, on the border with Lombardy. In this area long time-series of groundwater level, starting from the 1960s, have been collected in 16 wells. Water table data have a good completeness (in the majority of the cases &gt;90%). Firstly, the groundwater hydrodynamic behaviour, based on water table levels, was investigated to highlight the response of groundwater to the recharge. A basic statistical analysis was performed (mean, median, standard deviation, maximum, minima), and then trends of water table levels were evaluated in order to better observe the long-term behaviour of groundwater. These analyses allowed to observe a groundwater hydrodynamic behaviour characterised by a repeating annual pattern (minimum in February/March and maximum in August/September) in correspondence to the period of irrigation. Moreover, trend analysis highlighted the presence of both wells with a decreasing water table (with maximum lowering of 4.3 m in 60 years) and wells with an increasing water table (with maximum rises of 2.8 m in 35 years). Furthermore, in most cases, it can be observed that all three trends analysed agree on being positive or negative. Future insights will be the comparison of these long time-series with the meteorological data, and the investigation of other factors (e.g. anthropic withdrawal, variations of cultivation practices and irrigation, geology of the subsoil) to better understand the causes of the water table fluctuations and trends.

Informing hydrogeological models with remotely sensed evapotranspiration

Remotely sensed evapotranspiration (ET) rates can provide an additional constraint on the calibration of groundwater models beyond typically-used water table (WT) level observations. The value of this constraint, measured in terms of reductions in model error, however, is expected to vary with the method by which it is imposed and by how closely the ET flux is dependant to groundwater levels. To investigate this variability, four silvicultural sites with different access to groundwater were modeled under three different model-data configurations. A benchmark model that used only WT levels for calibration was compared to two alternatives: one in which satellite remotely sensed ET rates from MODIS-CMRSET were also included in model calibration, and one in which the satellite ET data were assimilated, through the Ensemble Kalman Filter, into the model. Large error reductions in ET flux outputs were achieved when CMRSET data were used to calibrate the model. Assimilation of CMRSET data further improved the model performance statistics where the WT was &amp;lt; 6.5 m deep. It is advantageous to use spatially distributed actual ET data to calibrate groundwater models where it is available. In situations where vegetation has direct access to groundwater, assimilation of ET observations is likely to improve model performance.