Water Table Variations Research Articles

Probabilistic Retro-analysis of Failed OB Dump on the Weak Ground with Water Table Variation and Varied Preventive Measures

Probabilistic Retro-analysis of Failed OB Dump on the Weak Ground with Water Table Variation and Varied Preventive Measures

Utilizing Data-Driven Approaches to Forecast Fluctuations in Groundwater Table

Accurate forecasting of fluctuations in groundwater table is crucial for the effective management of regional water resources. This study explores the potential of utilizing remotely sensed satellite data to predict and forecast water table variations. Specifically, two Artificial Neural Network (ANN) models were developed to simulate water table fluctuations at two distinct well sites, namely BA Ea 18 and FR Df 35 in Maryland. One model leveraged the relationship between variations in brightness temperature and water table depth, while the other model was founded on the association between changes in soil moisture and water table depth. These models were trained and validated using recorded water table depths from the aforementioned wells, brightness temperature data acquired from the Advanced Microwave Scanning Radiometer—Earth Observing System (AMSR-E), and soil moisture information generated using the Land Data Assimilation System (LDAS). All models exhibited strong performance in predicting and forecasting water table fluctuations, with root mean square errors ranging from 0.043 m to 0.047 m for a 12-month forecasting horizon. Sensitivity tests revealed that the models displayed greater sensitivity to uncertainties in water table depth compared to uncertainties in both brightness temperature and soil moisture content. This underscores the feasibility of constructing an ANN-based water table prediction model, even in cases where high-resolution remotely sensed data is unavailable. In such situations, the model’s efficacy is contingent on the compatibility of the time series trends in data, such as brightness temperature or soil moisture, with those observed at the study site.

Challenges of Including Wet Grasslands with Variable Groundwater Tables in Large-Area Crop Production Simulations

Large-scale assessments of agricultural productivity necessitate integrated simulations of cropland and grassland ecosystems within their spatiotemporal context. However, simultaneous simulations face limitations due to assumptions of uniform species distribution. Grasslands, particularly those with shallow groundwater tables, are highly sensitive to water availability, undergoing rapid species composition changes. We hypothesised that predicting above-ground biomass (AGB) remains challenging due to these dynamic responses. Ten years of data from four lysimeters at a German wet grassland site, with varying water table treatments, was utilised to test this hypothesis. Correlation analysis revealed a strong positive indirect effect of the water regime on AGB, with a one-year time lag (r = 0.97). The MONICA model initially exhibited fair agreement (d = 0.69) in simulating Leaf-Area-Index (LAI) but performed poorly in replicating AGB (d = 0.3). After removing the species composition change effect from the LAI and AGB datasets, the simulation notably improved, with the overall relative root mean square error (rRMSE) of AGB decreasing from 1.55 to 0.90 between the first and second simulations. This demonstrates MONICA’s ability to predict grass growth patterns amidst changing water supply levels for constant species composition. However, it needs a competition model to capture biomass growth changes with varying water supply.

Holocene histories of biome stability in northern Amazonian savannas

Paleoecological analysis of three lake sediment cores from the Roraima savannas in northern Brazil revealed systems dominated by Poaceae pollen throughout most of the Holocene. A slight increase of palms and woody taxa, probably linked to wetter conditions, is observed during the last 1000 years but is more noticeable after 300 and 150 calibrated years BP (yr BP) respectively. Charcoal was present throughout affirming the importance of fire for the landscape but showed the highest values mostly in the last millenium. Poaceae pollen size spectra varied considerably, showing more variability than the overall pollen record. Despite evidence of some climate change in the Holocene, these savannas were stable systems. The sedimentary records showed gaps in deposition between 10,000 and 7800 yr BP and between 2500 and 1200 yr BP, suggesting dry periods during which lakes most likely dried out or became impermanent and highlighting the sensitivity of these lakes to local water table variation. The establishment of the modern climate in the region is evident after 1000 yr BP.

The mid‐latitude hydrolaccolith of the Spanish Central System (Southern Europe): A top‐to‐bottom integration of geomatic, geophysical and sedimentary datasets for characterising a singular periglacial landform

AbstractPermafrost study in the Spanish Central System (~41°N) has remained elusive in past decades. Although numerous periglacial features have been described, none has yielded conclusive information about the existence/distribution of permafrost across these mountains. This work focuses on integrating light detection and ranging and unmanned aerial vehicle data with geophysical methods and sedimentary records, along with preliminary thermal information, for the comprehensive study of a frost mound. The singularity of this feature resides in its location, currently dominated by a seasonal frost regime, and its size reaching 59 m long, 22.5 m wide and 4 m high, representing the largest landform of this type in Iberia. From top‐to‐bottom, the internal structure comprises three resistivity units (G1, G2 and G3). The most superficial unit (G1) consists of a sequence of burial soils alternating with sand and silts, with pebbles and gravel at the bottom, followed by a high porous layer that belongs to a landslide deposit (G2), likely composed of gravel and pebbles laying over unit G3 (bedrock). Calibrated 14C ages suggest this landform formed at least ~4300 years ago during the mid‐Holocene. Finally, the preliminary surface thermal map indicates the presence of sectors affected by strong thermal gradients likely driven by water table variations. Our results conclude that the dynamics are primarily controlled by the seasonal frost regime influencing local subsurface drainage, which allows us to classify this landform as a hydrodynamic pingo‐like structure. We also demonstrate that our approach is suitable for assessing the evolution of this type of periglacial landform. Implementing long‐lasting annual monitoring programmes would help to understand local periglacial dynamics better.

First record of plant-plant facilitative interaction from the Moscovian (Pennsylvanian, upper Carboniferous) of North China

Fallen logs acting as a seedbed for trees to aid the regeneration of vegetation is a common ecological strategy in modern forests. However, the origin, occurrence, and evolution of this nurse log strategy in the geological time is unclear. Here we report a ca. 310-million-year-old permineralized cordaitalean tree trunk from the Moscovian (Pennsylvanian, upper Carboniferous) Benxi Formation in Yangquan City, Shanxi Province, North China, with evidence of probable cordaitalean rootlets growing inside the trunk. The specimen is interpreted as a nurse log for regeneration of cordaitaleans in coastal lowlands. It provides the first glimpse of plant-plant facilitative interaction between Pennsylvanian cordaitaleans in Cathaysia. We interpret that the Moscovian cordaitalean seedlings preferentially established on the fallen log owing to the ability of the rotting wood to store fresh water. The nurse log provided a stable substrate in an environment with episodic salinity and/or water table variations. In combination with previous records, it is suggested that a sophisticated terrestrial ecosystem with multiple interactions between plants and other organisms have developed on the central North China Craton no later than the Middle Pennsylvanian.

Determination of groundwater potential zones on the eastern slope of Mount Cameroon using geospatial techniques and seismoelectric method

In complex hard rock terrain where the population suffers from water scarcity, the use of site-specific single-method surface geophysical surveys to prospect for groundwater is a common practise. However, this has not completely solved the problem of drilling dry wells. To combat this failure, geospatial data and the analytical hierarchy process (AHP) are being used as supporting techniques to increase the chance of success. This study had the aim of generating a groundwater potential zones (GWPZ) map of the complex strato-volcanic terrain of Buea by integrating geospatial techniques, AHP, and the seismoelectric method. Five factors influencing groundwater recharge were used to define the groundwater potential zones. Via the AHP and weighted overlay methods, five classes of groundwater potential zones were delineated: very poor, poor, moderate, good, and very good. More than half of the study area has good to very good groundwater potential. Lastly, the GWPZ model is validated with an iso-conductivity map from a seismoelectric survey and existing static water level data. The iso-conductivity map revealed four main conductivity zones that correlate positively with the GWPZ map. The northwestern part of the study area is characterised by moderate groundwater potential, poor formation conductivity, and dry boreholes. There is an uneven distribution of groundwater and variable water table depth in the area. The results of this study are very encouraging, and the integrated approach used has proven to be efficient in determining groundwater potential zones in complex volcanic terrain.

A feasibility study on time-lapse transient electromagnetics for monitoring groundwater dynamics

Time-lapse geophysical studies have been used as noninvasive tools to study subsurface processes. However, compared to direct current resistivity methods, the transient electromagnetic (TEM) method has not been explored in much detail for time-lapse investigations. Here, we introduce the use of a monitoring TEM (mTEM) system and methodology for long-term groundwater monitoring purposes. The system can run measurements automatically and the modeling approach uses a time-constrained inversion (TCI) scheme based on an existing laterally constrained inversion scheme. Instead of lateral constraints that traditionally ensure lateral coherency between measurements, temporal constraints are used to control the temporal coherency between measurements. Synthetic analysis demonstrates that very tight time constraints on resistivities and a time constraint on the depth to the water table fixed at a fraction of the expected annual water table variation is needed to track water table changes at the decimeter level. Furthermore, the synthetic analysis indicates that the mTEM method can track annual variations in the water table with amplitudes as low as 0.6 m with a mean absolute error of 0.2 at depths between 16 m and 30 m. A field example consisting of 233 1D TEM measurements acquired over 10 months using the mTEM instrument supports the synthetic results. The estimated water table depth from the TCI scheme reproduces the variation in the water table accurately, as confirmed by measurements from a water level data logger in a nearby well. The differences between the results from the TEM monitoring system and the diver measurements are in the range of ±0.1 m with an average absolute difference of 0.05 m. This study demonstrates the potential to monitor changes in the groundwater level noninvasively.

Analysis and interpretation of natural variations in water table and groundwater recharge of coastal aquifer system in the coastal plain of Rio Grande do Sul, Brazil

Analysis and interpretation of natural variations in water table and groundwater recharge of coastal aquifer system in the coastal plain of Rio Grande do Sul, Brazil

Mineral organic carbon interactions in dry versus wet tundra soils

Mineral organic carbon interactions (aggregation, organo-mineral associations and organo-metallic complexes) enhance the protection of organic carbon (OC) from microbial degradation in soils. The northern circumpolar permafrost region stores between 1,440 and 1,600 Pg OC of which a significant portion is already thawed or about to thaw in coming years. In the light of this tipping point for climate change, any mechanism that can promote OC stabilization and hence mitigate OC mineralization and greenhouse gas emissions is of crucial interest. Here, we study interactions between metals (Fe, Al, Mn and Ca) and OC in the moist acidic tundra ecosystem of Eight Mile Lake, near Healy, AK, USA. We collected thirteen cores (124 soil samples) in late summer 2019 with shallow and deep active layers (45 to 109 cm deep) and varying water table depths. We find that between 6% and 59% of total OC in Eight Mile Lake tundra soils is mineral-associated (mean 20%), in organo-mineral associations (association between poorly crystalline oxides and OC) and in organo-metallic complexes (associations between Fe, Mn, Al, Ca polyvalent cations and organic acids). We find that total Fe and Mn concentrations can be used as good proxies to assess the reactive pool of these metals able to form associations with OC, i.e., poorly crystalline oxides or metals complexed with OC. We observe that in the active layer, mineral OC interactions are mostly as organo-metallic complexes with Fe cations, with an accumulation at the water table level acting as a soil redox interface. In waterlogged soils with a water table level above surface, no such accumulation of OC-Fe complexes is found due to the absence of a redox interface below soil surface. In the permafrost layer, we find that a combination of complexed metals and poorly crystalline Fe oxides act as reactive phases towards OC. Knowing that upon permafrost thaw tundra soils will become wetter or drier, the assessment of mineral-bound OC in drier or wetter tundra soils is a needed step to better constrain the changes in the proportion of non-protected OC more likely to contribute to C emissions from tundra soils.

Seasonal Environmental Controls on Soil CO2 Dynamics at a High CO2 Flux Sites (Piton de la Fournaise and Mayotte Volcanoes)

AbstractEnvironmental parameters drive seasonal soil CO2 efflux toward the atmosphere. However, their influence is not fully understood in contexts of high CO2 fluxes where CO2 accumulates in the subsurface. A prime example are volcanoes subject to continuous CO2 diffuse degassing rising from deep magmatic reservoirs, through the subsurface and up to the atmosphere. For many of these volcanoes where soil CO2 is monitored, a seasonal influence of the atmosphere and water table is observed but not characterized. Here, we compare variations of air temperature, atmospheric pressure, rainfall and water table level with near‐surface soil CO2 concentration by performing a time‐lagged detrended cross‐correlation analysis on years‐long time series from the volcanoes of Piton de la Fournaise and Mayotte. At Piton de la Fournaise, soil CO2 variations correlate best with air temperature variations (0.81) and water table variations (0.74). In Mayotte, soil CO2 variations correlate best with atmospheric pressure variations (−0.95). We propose that at Piton de la Fournaise, the thick vadose zone and high permeability favor CO2 transfer by thermal convection. Additionally, energy transfer is decoupled from mass transfer. Slow heat transfer from the atmosphere down to the accumulated CO2 layers in the subsurface results in a delayed influence of air temperature and of the water table level on the thermal gradient between the subsurface and the atmosphere, and consequently on the efficiency of the CO2 transfer. In Mayotte, we propose that the thin vadose zone and the presence of a network of large fractures favor CO2 transfer by barometric pumping.

Parametric Design and Field Behavior of Earthen Structures

The stability of earthen structures is governed by field uncertainties arising from material properties, environment loading, and slope geometry. This research devised a systematic approach to capture the effects of field uncertainties on the stability of natural and manmade slopes. New design charts were developed by incrementally changing slope geometry and randomly generating shear strength parameters. Subset simulation was used to determine the safe range of soil properties for various slopes. The charts were applied to three published case studies with distinct triggering mechanisms resulting from complex field settings. All of the investigated slopes were found to be stable (factor of safety (FOS) > 1.0) under the reported geometry and shear strength parameters while assuming no water table. The effects of soil properties’ variation and environmental conditions on fluctuating water table were captured through history matching. Results indicated three distinct failure mechanisms: foundation settlement of a glacial moraine till (Vernon, British Columbia) due to an increased pore water pressure during construction of the compacted fill (FOS = 1.45 without berms and 2.24 with berms); instability in the natural cut (FOS = 0.98) comprising layered glacio-lacustrine clays (Labret, Saskatchewan) due to saturation of the entire slope resulting from a long duration rainfall; and collapse of a compacted fill (FOS = 0.98) on a glacial moraine till (Hamelin Creek, Alberta) due to soil saturation arising from thawing of a frozen layer in the slope. This validation illustrates that the new approach fully captures environmental loading (resulting in water table variation in the slope) and partly captures construction practice and site geology via soil properties.

Analysis of observed performance of a deep excavation straddled by shallowly buried pressurized pipelines and underneath traversed by planned tunnels

The objective of this paper is to analyze the observed performance of a deep excavation facing severe restrictions from underground facilities or structures in Suzhou, China. The first source of the restrictions comes from two shallowly buried pressurized pipelines that straddle the excavation at an intersection angle of about 81°. The pipelines need to be well protected at the site during the construction to ensure the normal life of the local resident. The second source of the restrictions arises from the twin tunnels that are planned to be constructed beneath the excavation in the future for Suzhou Metro Line 14. The planned tunnels will be constructed using a tunnel boring machine, which necessitates the reservation of favorable conditions by the present excavation project. Because of these restrictions, the form of the excavation support system becomes complicated, and the performance of the excavation will inevitably differ from that of the common excavations. Based on a thorough analysis of the extensive field performance data collected by means of settlement points and inclinometers located within and adjacent to the excavation, the characteristics of the ground surface settlements, lateral ground movements, ground water table variations, vertical and lateral displacements atop diaphragm walls, vertical displacements atop lattice column, axial forces in concrete strut, and vertical and lateral pipeline deformations are captured. Despite the discontinuity of the peripheral retaining wall and the shortened wall height on the discontinuous sides, the ground and structural deformations are well controlled by the specially designed excavation support system. The pipelines are slightly uplifted by the suspension system, with the maximum vertical pipeline displacement being lower by an order of magnitude than the commonly observed maximum pipeline settlements in the literature. The existing empirical envelops are found to be site-specific in applicability, and are recommended to incorporate the field observations of this unusual deep braced excavation case history.

Evidence for older carbon loss with lowered water tables and changing plant functional groups in peatlands.

A small imbalance in plant productivity and decomposition accounts for the carbon (C) accumulation capacity of peatlands. As climate changes, the continuity of peatland net C storage relies on rising primary production to offset increasing ecosystem respiration (ER) along with the persistence of older C in waterlogged peat. A lowering in the water table position in peatlands often increases decomposition rates, but concurrent plant community shifts can interactively alter ER and plant productivity responses. The combined effects of water table variation and plant communities on older peat C loss are unknown. We used a full-factorial 1-m3 mesocosm array with vascular plant functional group manipulations (Unmanipulated Control, Sedge only, and Ericaceous only) and water table depth (natural and lowered) treatments to test the effects of plants and water depth on CO2 fluxes, decomposition, and older C loss. We used Δ14 C and δ13 C of ecosystem CO2 respiration, bulk peat, plants, and porewater dissolved inorganic C to construct mixing models partitioning ER among potential sources. We found that the lowered water table treatments were respiring C fixed before the bomb spike (1955) from deep waterlogged peat. Lowered water table Sedge treatments had the oldest dissolved inorganic 14 C signature and the highest proportional peat contribution to ER. Decomposition assays corroborated sustained high rates of decomposition with lowered water tables down to 40 cm below the peat surface. Heterotrophic respiration exceeded plant respiration at the height of the growing season in lowered water table treatments. Rates of gross primary production were only impacted by vegetation, whereas ER was affected by vegetation and water table depth treatments. The decoupling of respiration and primary production with lowered water tables combined with older C losses suggests that climate and land-use-induced changes in peatland hydrology can increase the vulnerability of peatland C stores.

The Role of Hydrogeological Monitoring in a Multidisciplinary Context for the Preservation of the Critical Zone in the Natural Reserve of Castelporziano Estate

Critical Zone (CZ) science has developed in recent years, involving different disciplines that vary depending on the specific research focus. This multidisciplinary approach highlights the relevance of the Underground component of the Critical Zone (UCZ) in regulating the water cycle, which can influence the complex equilibrium of the whole CZ. In this study, we analyze evolution during the time of different parameters, characterizing the saturated and unsaturated parts of the UCZ of the Castelporziano Estate, a natural reserve located in a coastal area close to Rome. The purposes of these activities are to monitor the potential depletion of groundwater resources and understand the recharge mechanism processes characterizing the aquifer in the framework of occurring climate changes, net of anthropogenic pressure. The long-term analyses of water table variations carried out over the last 25 years, allowed us to preliminarily identify four different ranges of the slope coefficient of the water table, characterizing different areas of the Estate. Specifically, the Northern, Central, and Coastal areas have shown a general depletion trend in piezometric levels, while in the Eastern area, a positive trend has been recognized. Additional long-term analysis of piezometric level variations allowed us to confirm the presence of the four recharge areas and compare annual recharge and water table levels to assess the relationship between the saturated UCZ and meteoric recharge in the identified areas. To evaluate the role of the unsaturated UCZ in recharge mechanisms, the water content in the first meter of soil has also been analyzed, showing different responses of outcropping sediments in capturing rainfall during different periods of the year and under different rainfall input conditions, highlighting the pivotal role of rainfall for the Castelporziano UCZ, both for deep recharge of the water table and for feeding the forest roots. Stable isotopes confirm that Castelporziano UCZ feeding is strongly dependent on local meteoric recharge, also highlighting that evaporation processes are active in a limited way. The obtained results assess that the monitoring of UCZ has a crucial role in the correct preservation of more complex environmental systems, which include groundwater resources and the coastal Mediterranean forest.

High‐Resolution Monitoring of Controlled Water Table Variations From Dense Seismic‐Noise Acquisitions

AbstractWater‐resource management has become a major global issue in a world threatened by climate change. High‐resolution geophysical methods may be of valuable help in monitoring the water masses, both in space and time. Passive seismic interferometry takes advantage of ambient seismic noise to recover the variations in seismic wave velocity induced by changes in groundwater. We present hereafter the time and space monitoring of an hydraulic dome artificially formed to prevent biological and chemical pollutants from entering the exploitation field of Crépieux‐Charmy (Lyon, France). We use a dense seismic network to passively monitor the water table changes induced by infilling of an infiltration basin at the water supply facility for the two million inhabitants of the Lyon Metropolis (France). We assess the hourly seismic velocity variations over 19 days, during which two filling and drainage cycles were performed. The use of a dense three‐component seismic network allows fine characterization of the seismic wavefield, and offers the possibility to include the analysis of 4,851 raypaths in a robust inversion algorithm based on ray theory. The velocity variations are mapped with high resolution. They are directly related to the water table variations and to residual water saturation changes within the unsaturated zone. This seismic experiment highlights the three‐dimensional (3D) implementation and evolution of a hydraulic dome under the infiltration basin. This dynamic information helps in the understanding and modeling of water flows between the water table and a river, which represents a fundamental issue for discussions on the effectiveness of the barrier.

Climate-driven Holocene ecohydrological and carbon dynamics from maritime peatlands of the Gulf of St. Lawrence, eastern Canada

Anticosti Island, located in the Gulf of St. Lawrence (GSL; Quebec, Canada) is covered by ~25% peatland ecosystems, and conditions supporting their development remain poorly documented. We present the first reconstructions of the ecohydrological conditions (vegetation successions and water table variations) and related carbon accumulation of two maritime peatlands (Pluvier; PLU and Pointe de l’Est; PTE) located on the eastern part of Anticosti Island. These ombrotrophic peatlands developed under the influence of the GSL sea-surface conditions in interaction with atmospheric circulation during the Holocene. Long-term apparent Rate of Carbon Accumulation (LORCA, g C m−2 a−1) at PLU (13.3) and PTE (16.8) are lower than the mean global value for northern peatlands (22.9), likely due to high wind exposure. Results show that despite the earlier peat inception at PLU (9440 cal a BP) before PTE (6250 cal a BP), the fen-bog transition of both peatlands occurred almost synchronously (4540 and 5070 cal a BP respectively), suggesting favourable hydroclimatic conditions for peat growth. A slowdown in peat accumulation combined with dry and variable hydrological conditions after ca. 3300 cal a BP in the two studied peatlands coincided with the transition from the mid-Holocene to the Neoglacial cooling. At ca. 800 cal a BP, the shift from wet Sphagnum to dry ligneous peat corresponds to the transition from the Medieval Climate Anomaly to the Little Ice Age. Cooling periods, characterized by a decrease in incident solar radiation and the incursion of cold and dry Arctic air masses into the GSL, are marked by a decrease in peat accumulation, especially at PLU, due to its higher wind exposure, which influenced reduced snow cover thickness as well as frost penetration and duration through the peat.

Alluvial ichnofacies from Upper Triassic red beds in India: Implications for palaeoenvironment and palaeoclimate

Trace fossils are highly sensitive to the hydrodynamic conditions of depositional systems, substrate, and climate and hence yield information about spatio-temporal changes in palaeoenvironment and palaeoclimate. In this paper, we report alluvial trace fossil assemblages from the Upper Triassic Tiki Formation of the Rewa Basin, central India. Based on detailed facies analysis and architecture, two depositional environments are identified in this formation: (1) perennial braided channel belts and (2) extensive and complex floodplains containing ephemeral small fluvial channels, lakes, and crevasse splay deposits. Upper flow regime primary structures in laterally extensive sandstones encased in the floodplain deposits indicate short-lived high magnitude flood discharge, suggestive of seasonal climates. Trace fossils are sporadically distributed through these facies, generally in suites of low abundance, although in places the bioturbation index is higher. Three major ichnofacies, namely Skolithos, Scoyenia and Mermia are recognized, based on the association of different trace fossils preserved in the channel, crevasse splay of proximal floodplain and pond/lake of distal floodplain deposits, respectively. Vertical Beaconites in palaeosols and an abrupt change from Skolithos to Scoyenia ichnofacies indicate a highly variable water table, controlled by seasonal precipitation. The transitions between the Skolithos, Scoyenia and Mermia ichnofacies reveal that trace fossil preservation was variously controlled by channel abandonment, floodplain dewatering, substrate desiccation or periodic waterlogging of overbank areas. Specifically, increased water discharge over the floodplain during high precipitation, followed by post-flood recovery of hot, dry, low-water table conditions may have been a key controlling factor in shaping the ichnological characteristics of these Upper Triassic red beds.

Climatic Control on Spatial Distribution of Water Storage at the Catchment Scale: A Framework for Unifying Saturation Excess Runoff Models

AbstractThis paper aims to investigate the connection between TOPography‐based hydrological model (TOPMODEL) and Variable Infiltration Capacity (VIC) model through virtual experiments from the perspective of water table and storage at the catchment scale. A simple finite‐difference groundwater flow model was built for a hypothetical catchment forced by a sequence of recharges. A steady‐state water table under a low recharge rate is used as the climatic lower limit, above which the pore space is considered as the maximum storage capacity. When the water table is shallow, the land surface is a good proxy of the water table as assumed in the original TOPMODEL, and the underlying water storage distribution curve is similar as the maximum storage capacity distribution curve. When the water table is deep, the climatic lower limit is a good proxy of water table, and the storage is approximately spatially uniform over the unsaturated area as assumed in the VIC model. The systematic variation of water table and storage distribution potentially provides a framework for unifying the TOPMODEL and VIC model.

Investigating the microbiological risks associated with urban flooding in the UK

Over the last 30 years, the frequency and occurrence of intense rainfall, and thus extreme hydrological events –flooding- has steadily increased. Drainage infrastructure in the UK was not designed for a changing climate, and many sewer systems in densely populated urban areas, are unable to cope. Sewage overflow and surface run off in urban areas can act as vectors for the dissemination of pathogens, known to cause disease among human populations. Most of the previous studies in this field have focused on using faecal indicators such as E.coli when assessing the public health risk of floodwater [1]. However, traditional indicators do not accurately reflect the true risk that urban flooding poses [2]. Little is understood in regards to the survivability and behaviour of pathogens in different urban settings, which are fundamental to determine potential risks to public health. Previous investigations in UK waterlogged soils have shown a clear response of microbial communities to water table variation, temperature, and nutrient availability in soil profiles [3]. This research aims to investigate, using advanced molecular methods, the dynamics of pathogens (i.e. movement through soil and survival rates), and microbial interactions at the soil/water interface- collecting information from field work studies and laboratory-controlled experiments. The outcomes from this research will inform future management strategies of flooded sites that will aid to protect public health.