High Hydraulic Conductivity Research Articles

Sustainability of an Open-Loop GWHP System in an Italian Alpine Valley

Shallow geothermal systems (SGSs) for building climatization represent an advantageous alternative to traditional air-conditioning systems, resulting in economic and environmental benefits. Installation of these systems requires knowledge of site-specific geological and hydrogeological conditions, which in feasibility studies are often evaluated only at the single plant scale, lacking a comprehensive view and risking not to guarantee the system sustainability over time. In this paper a methodology for the sustainable design of SGSs is presented. The methodology is developed from an example on the aquifer scale in Longarone (Belluno, Italy), where three groundwater heat pumps (GWHPs) were installed in an industrial area located in a mountain basin hosting a coarse-grained phreatic aquifer, characterized by sediments with high hydraulic conductivity and proximal to a large river (Piave River). Open-loop systems were first analyzed through numerical modeling using FEFLOW software, identifying peculiar features of the aquifer, due to its interaction with surface waters, and suggesting the possibility of its greater geothermal exploitation. Subsequently, a relationship between flow rates and thermal plume extensions was obtained, which is useful to providing support in the evaluation of potential interference with neighboring systems. The study at the aquifer scale proved representative of the system, highlighting the criticalities of the area, such as trends of aquifer temperature alteration, interference between plants, and thermal feedback.

Influence of injection methods on calcareous sand cementation by EICP technique

Calcareous sands are widely distributed on continental shelves, coastal zones, islands and reefs in the tropical oceans. For being used as construction materials, calcareous sands should be artificially treated to improve their engineering properties. Enzymatically induced carbonate precipitation (EICP) is an innovative soil treatment technique. In this paper, urease was extracted from soybean powder using artificial seawater for calcareous sands cementing by the EICP technique. Cementation tests were conducted with three injection methods (the pre-mixed, staged and proposed parallel injections) and two injection rates (2 and 5 mL/min). The hydraulic conductivity, shear wave velocity (SWV) and unconfined compressive strength tests were conducted and the cementation effects were evaluated. The hydrodynamic diameter of the particles generated in the mixed solutions was measured with reaction time by a laser particle size analyzer and the influence of injection rate on the CaCO3 distribution in the specimen was discussed. The coefficient of variation of the SWV values along the cemented specimen height was calculated for evaluation of the cementation uniformity. Results show that a high injection rate was conducive to reducing clogging and improving the cementation uniformity by completing injection within the urea hydrolysis phase. The promising parallel injection method proposed in this study provided a lag time for reaction by simultaneous injection of crude urease and cementation solutions using two separate tubes. Specimens treated at a high parallel injection rate were uniformly cemented with high mechanical strengths and high overall hydraulic conductivities because of a high proportion of CaCO3 in contact-cementing distribution.

High abscisic acid and low root hydraulic conductivity may explain low leaf hydration in 'Mandarin' lime exposed to aluminum.

The first symptom of aluminum (Al) toxicity is the inhibition of root growth, which has been associated with low leaf hydration, with negative consequences for leaf gas exchange including stomatal conductance (gs) observed in many plant species. Here we asked whether low leaf hydration occurs before or after the inhibition of root growth of Citrus × limonia Osbeck ('Mandarin' lime) cultivated for 60days in nutrient solution with 0 and 1480μM Al. The length, diameter, surface area and biomass of roots of plants exposed to Al were lower than control plants only at 30days after treatments (DAT). Until the end of the study, estimated gs (measured by sap flow techniques) was lower than in control plants from 3 DAT, total plant transpiration (Eplant) and root hydraulic conductivity (Lpr) at 7 DAT, and midday leaf water potential (Ψmd) and relative leaf water content at 15 DAT. Abscisic acid (ABA) in leaves was twofold higher in Al-exposed plants 1 DAT, and in roots a twofold higher peak was observed at 15 DAT. As ABA in leaves approached values of control plants after 15 DAT, we propose that low gs of plants exposed to Al is primarily caused by ABA, and the maintenance of low gs could be ascribed to the low Lpr from 7 DAT until the end of the study. Therefore, the low leaf hydration in 'Mandarin' lime exposed to Al does not seem to be caused by root growth inhibition or by a simple consequence of low water uptake due to a stunted root system.

Inverse estimation of hydraulic parameters of soils with rock fragments

The application of inverse modeling to determine the hydraulic properties of layered soils with rock fragments (RF > 2 mm) is associated with complex challenges such as selecting suitable hydraulic functions and defining a strategy to optimize many parameters. These two issues were addressed in this study by performing field drainage experiments in layered soil profiles (three layers) with different particle size distributions and different percentages of RF. Water contents (θ) and pressure heads (h) were monitored at different soil depths during drainage experiments (h ≥ −200 cm). Data of θ and h for a drier range (h < −5000 cm) were determined with a dew point potentiometer on disturbed soil samples. The unimodal and bimodal van Genuchten-Mualem functions were evaluated, and their parameters were optimized using the Hydrus-1D “Inverse solution”. The RETC curve fitting software was used to estimate the second set of parameters of the bimodal function. The parameters for the uni- and bimodal models (15 and 27 parameters, respectively) were repeatedly optimized by fixing some parameters while estimating others. The unimodal van Genuchten-Mualem function provided a satisfactory fit of θ and h measurements only when either drainage or dew point potentiometer measurements were used. On the other hand, the bimodal van Genuchten-Mualem function provided a satisfactory fit of θ and h measurements when both sets of data (drainage and dew point potentiometer measurements) were used simultaneously. Furthermore, the optimized parameters were physically consistent except for a few high saturated hydraulic conductivity values. Therefore, bimodal functions should be considered to represent the hydraulic properties of soils with RF. The problem of many calibrated parameters when using bimodal functions can be managed using sequential optimization, which allowed us to estimate 27 parameters for layered soils with RF successfully.

INFLUENCE OF ENGINEERING PROPERTIES OF SOILAND GROUNDWATER MOVEMENT ON GULLY DEVELOPMENT IN RAFINGORA, NORTHERN BIDA BASIN, NIGERIA

The formation and expansion of gullies in Rafingora community, northern sector of the Bida Basin, Nigeria was investigated. This was aimed at determining the controlling factors for gully development in the area, using field gully parameter measurements, hydrogeological mapping and geotechnical investigation of soils from gully sites. U-shaped gullies were mapped with sliding, slumping and block fracturing as the main modes of gully propagation. Relief is gentle; slope angles range from 1.58° to 1.96°, indicating little or no influence of elevation on gully development. Gullies were found to be deeper than 3m, with drainage area of more than 30m. Depth to water in open wells ranges from 5.5m in the north-eastern part to about 16.4m in the south-western part. Gullies in the north-eastern side are mostly shallower than the water table, contrary to the situation in the south-western part. This shows a direct relationship between water table elevation and gully propagation and is further exacerbated by the relatively high average hydraulic of soils. The soils have low plasticity, cohesion, angle of internal friction (AIR) and maximum dry density (MDD). A combination of these poor geotechnical properties makes the soils friable and crumbles easily when in contact with water and offers very little resistance to erosion. Conclusively, gully development in Rafingora is influenced more by bottom erosion due to high hydraulic conductivity and seepage forces, rather than by overland runoff. Reclamation attempts may consider lowering groundwater levels as a major strategy for erosion control in the area.

Experimental Investigation of the Effects of Porosity, Hydraulic Conductivity, Strength, and Flow Rate on Fluid Flow in Weakly Cemented Bio-Treated Sands

Fluid injection in a porous medium is the underlying mechanism for many applications in the fields of groundwater hydraulics, hydrology and hydrogeology, and geo-environmental engineering and in the oil and gas industry. Fluid flow experiments in porous media with a viscous fluid at varying injection rates were conducted in a modified Hele-Shaw setup. The granular media were three-dimensional bio-cemented sands of various grain sizes across various cementation levels, generating a matrix of various hydraulic conductivities, porosities, and strengths. The fluid injection experiments showed that a cavity-like fracture developed, which transitioned to crack-like fractures at higher cementation levels (hence, higher strength). As the flow rate increased, less infiltration was evident and higher breakdown pressure was observed, with propagation pressure reducing to zero. It was harder to induce an opening in cemented specimens with higher hydraulic conductivity and a larger pore network despite their lower strength due to excessive infiltration dominance, which inhibited the build-up of pressure required to generate a fracture. The results of this study suggest that, when designing fluid injection programs, the combined effects of hydraulic conductivity and strength need to be carefully considered.

Using A Subsurface Vertical Flow System to Remediate Municipal Wastewater

The goal of this study is to determine the efficacy of plants in the treatment of municipal wastewater (MWW) utilizing the aquatic plant common reed, also known as Phragmites australis. Two glass basins with dimensions of (60 cm x 26 cm) and a height of (60 cm x 26 cm) have been developed for this purpose (30 cm). In this investigation, two basins were employed: one served as a reference, while the other was used to conduct tests using synthetic and actual city wastewater. The plant treatment basins with a vertical subsurface flow (VSSF) system was used in this investigation because it provides greater ventilation. Furthermore, the retention duration is many hours due to water molecules penetrating the basin's layers of packing materials, which have a rather high hydraulic conductivity. Three layers of aggregates, sand, and agricultural sand were used to cover the basins' bases: the first layer was 3 cm of aggregates, the second was 3 cm of sand, and the final layer was 4 cm of agricultural sand. Before beginning the experiment, the plants were acclimated for two weeks. To imitate municipal wastewater, lab-created synthetic wastewater was employed. Samples were collected and tests were performed after four weeks of running the trials to determine certain significant pollution indicators and their elimination percentage. TDS= 20.6 %, TSS= 65 %, BOD5=75 percent, COD=64.1 %, and TH= 47.2 % were the findings. The capacity of Phragmites australis to function as a biofilter in the treatment process was demonstrated by its use in the phytoremediation of municipal wastewater.

Performance investigation of the solar direct-driven wood regenerator in liquid desiccant air-conditioning systems

Liquid desiccant air-conditioning (LDAC) systems are one of the most promising alternatives to conventional air conditioning systems due to the high energy efficiency. The most energy-consuming part of LDAS system is desiccant regeneration, while traditional regeneration methods often fail to balance the energy grade and energy efficiency. Inspired by solar heat localization for seawater desalination, the regeneration performance of this novel method has been investigated. Here, we fabricated a wood-based regenerator by drilling holes and spaying Chinese ink, which features high sunlight absorption and strong water transportation ability. Owing to the high hydraulic conductivity of drilled holes and low thermal conductivity of wood substrate, liquid desiccant can be regenerated efficiently with a low-temperature rise. Even for 40 wt% CaCl2 solution at 30 °C, the regeneration rate and efficiency can reach 0.64 kg·m−2·h−1 and 43.2 %. Comparisons between solar interfacial regeneration method and other traditional regeneration methods were also conducted. Results show that the solar interfacial method can significantly improve the regeneration rate at the same temperature. Given the low manufacturing cost and operating cost, high regeneration rate and efficiency, superior salt-rejecting property, and low-temperature rise, the wood regenerators based on solar interfacial regeneration show great potential in LDAC systems.

How do functional traits influence tree demographic properties in a subtropical monsoon forest?

Abstract Functional traits are good predictors of plant responses and adaptations to ever‐changing environments. However, forecasting forest community dynamics is challenging because the relationships among different tree demographic properties (growth, mortality and recruitment) and how functional traits are associated with tree demography remain largely unknown. Here, in a 20‐ha subtropical forest permanent plot, we quantified the rates of tree growth, mortality and recruitment across 53 dominant tree species (diameter at breast height; DBH ≥ 1 cm) from 2005 to 2020. Functional traits that are closely related to plant photosynthesis, nutrients, hydraulics and drought tolerance were measured. We found that tree growth rate (GR) varied independently from rates of tree mortality and recruitment. Hydraulic conductivity was positively correlated with GR (explaining 27% variation—the strongest relationship observed) whereas wood density was negatively correlated with GR. Leaf life span was negatively related to tree mortality. Species with high carbon assimilation rate, nutrient concentration and hydraulic conductivity had high recruitment rates. Leaf turgor loss point was unrelated to plant demography. Principal component analysis revealed that species with quick resource acquisition rates had high rates of growth and recruitment. Our results illustrate that the correlations among tree demographic properties were weak in this subtropical forest with monsoonal climate. Most notably, against expectations, there was no observed trade‐off between growth and mortality. Individual functional traits explained up to 27% of each demographic rate. Variation in recruitment rate was aligned with traits indexing the leaf economic spectrum and also plant hydraulic variation. A better understanding of the role of disturbances on trait–demography relationships would help build a deeper and more nuanced understanding of the ecology of subtropical monsoon forests. Read the free Plain Language Summary for this article on the Journal blog.

A Systematic Review of the Scientific Literature on Pollutant Removal from Stormwater Runoff from Vacant Urban Lands

Even though the common acknowledgment that vacant urban lands (VUL) can play a positive role in improving stormwater management, little synthesized literature is focused on understanding how VUL can take advantage of different stormwater control measures (SCMs) to advance urban water quality. The project aims to provide urban planners with information on the remediation of vacant lands using urban runoff pollutant removal techniques. To find the most effective removal method, relevant scholarly papers and case studies are reviewed to see what types of vacant land have many urban runoff pollutants and how to effectively remove contaminants from stormwater runoff in the city by SCMs. The results show that previously developed/used land (but now vacant) has been identified as contaminated sites, including prior residential, commercial, industrial, and parking lot land use from urban areas. SCMs are effective management approaches to reduce nonpoint source pollution problems runoff. It is an umbrella concept that can be used to capture nature-based, cost-effective, and eco-friendly treatment technologies and redevelopment strategies that are socially inclusive, economically viable, and with good public acceptance. Among these removal techniques, a bioretention system tends to be effective for removing dissolved and particulate components of heavy metals and phosphorus. Using different plant species and increasing filter media depth has identified the effectiveness of eliminating nitrate nitrogen (NO3-N). A medium with a high hydraulic conductivity covers an existing medium with low hydraulic conductivity, and the result will be a higher and more effective decrease for phosphorus (P) pollutants. In addition, wet ponds were found to be highly effective at removing polycyclic aromatic hydrocarbons, with removal rates as high as 99%. For the removal of perfluoroalkyl acid (PFAA) pollutants, despite the implementation of SCMs in urban areas to remove PFAAs and particulate-related contaminants in stormwater runoff, the current literature has little information on SCMs’ removal of PFAAs. Studies have also found that VUL’s size, shape, and connectivity are significantly inversely correlated with the reduction in stormwater runoff. This paper will help planners and landscape designers make efficient decisions around removing pollutants from VUL stormwater runoff, leading to better use of these spaces.

Relationships between Xylem Transport, Anatomical, and Mechanical Traits at Organ Level of Two Cupressaceae Species

Compared to arid regions, forests in humid regions can be more vulnerable to drought as they are not used to, and thus not adapted to, water stress. Therefore, it is vital to understand the drought responses of woodland species in humid areas. Xylem structures and functions of species growing in the humid regions are the key to their drought responses. Two Cupressaceae species (including three taxa: Sequoia sempervirens, Taxodium distichum and its variety Taxodium distichum var. imbricatum) grown in a mesic common garden were targeted, and their xylem hydraulic function (hydraulic conductivity, Ks; cavitation resistance, P50), anatomical structure (tracheid and pit structure), and mechanical support (wood density, WD; tracheid thickness-to-span ratio, Ttob) were measured. Likewise, we analyzed the differences in hydraulic function and anatomical structure of xylem in branches and roots, and the quantitative relationship between xylem water transport, anatomical structure, and mechanical support. Our results showed that roots had a higher hydraulic conductivity and a weaker cavitation resistance than branches. There was no safety–efficiency trade-off in the branches and roots within species. Tracheid mechanical support had a trade-off relationship with Ks or P50 (negative correlation appeared in branch Ks ~ WD and root Ks ~ Ttob of S. sempervirens, root P50 ~ Ttob of T. distichum var. imbricatum, and branch P50 ~ WD). There was no trade-off in anatomical structure, which led to no safety–efficiency trade-off in xylem function. Our results suggest that the two species exhibit both low efficiency and low safety in xylem, and that there is no safety–efficiency trade-off in branches and roots. The reason behind this is that the structural demand for high safety and high efficiency differs (i.e., the root Ks of S. sempervirens was strongly controlled by Dh; in contrast, the root P50 of S. sempervirens was strongly determined by tracheid density, N). Namely, the structural basis for a safety–efficiency trade-off does not exist and therefore trade-offs cannot be achieved.

A polydimethylsiloxane-based sponge for water purification and interfacial solar steam generation

A better knowledge for the design and synthesis of low-cost, novel porous materials is highly desirable in various fields such as recyclable solar desalination and liquid recycling. Herein, a polydimethylsiloxane-based sponge with a web-like three-dimensional (3D) interconnected porous structure was developed for effective recovery of liquids and the continuous interfacial solar steam generation (ISSG). The sponge is capable of conducting directional transport of oil or organic solvents at temperatures above 32 °C while automatically controlling the desorption of the organic phase below 28 °C. The synergistic combination between high light absorption (above 95 %) and light-to-heat conversion efficiency (99.87 %) resulted in a considerably high seawater evaporation rate (1.66 Kg m−2h−1) under 1 sun. The self-regeneration of the evaporator is facilitated by the salt barrier function of the large channels of the smart sponge with high hydraulic conductivity. This sponge can maintain a maximum evaporation rate up to the 5 consecutive days operation with the co-benefit of real-time regeneration and the reversible switching of the wettability. The reusable smart sponge evaporators are highly efficient in generating clean water from seawater with satisfactory ion rejection rates (above 99.6 %). As such, the prepared sponge shows great potential in environmental restoration, metal recovery, and water regeneration.

Many paths to one goal: Identifying integrated rice root phenotypes for diverse drought environments.

Drought is a major source of yield loss in the production of rice (Oryza sativa L.), and cultivars that maintain yield under drought across environments and drought stress scenarios are urgently needed. Root phenotypes directly affect water interception and uptake, so plants with root systems optimized for water uptake under drought would likely exhibit reduced yield loss. Deeper nodal roots that have a low metabolic cost per length (i.e., cheaper roots) via smaller root diameter and/or more aerenchyma and that transport water efficiently through smaller diameter metaxylem vessels may be beneficial during drought. Subsets of the Rice Diversity Panel 1 and Azucena × IR64 recombinant inbred lines were grown in two greenhouse and two rainout shelter experiments under drought stress to assess their shoot, root anatomical, and root architectural phenotypes. Root traits and root trait plasticity in response to drought varied with genotype and environment. The best-performing groups in the rainout shelter experiments had less plasticity of living tissue area in nodal roots than the worst performing groups. Root traits under drought were partitioned into similar groups or clusters via the partitioning-around-medoids algorithm, and this revealed two favorable integrated root phenotypes common within and across environments. One favorable integrated phenotype exhibited many, deep nodal roots with larger root cross-sectional area and more aerenchyma, while the other favorable phenotype exhibited many, deep nodal roots with small root cross-sectional area and small metaxylem vessels. Deeper roots with high theoretical axial hydraulic conductance combined with reduced root metabolic cost contributed to greater shoot biomass under drought. These results reflect how some root anatomical and architectural phenes work in concert as integrated phenotypes to influence the performance of plant under drought stress. Multiple integrated root phenotypes are therefore recommended to be selected in breeding programs for improving rice yield across diverse environments and drought scenarios.

Mechanical Strength, Water Seepage and Microstructure of a Novel Landfill Solidified Sludge Liner Material

In order to prepare a novel landfill liner material, we used industrial calcium-containing waste (slag, fly ash, and desulfurized gypsum) to solidify municipal sludge. The mechanical and permeability properties of the solidified sludge material (SSM) were evaluated using straight shear, uniaxial compression, and permeability tests. The hydration products, microscopic morphology, and elemental composition of the SSM after the wet and dry cycles were analyzed using a combination of scanning electron microscopy (SEM + EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The SSM has high strength and low hydraulic conductivity. The values of cohesion c and internal friction angle φ reached 0.45–3.31 MPa and 6.52–36.28°. The SSM exhibited a compressive strength of 0.93–11.67 MPa and hydraulic conductivity of 4.80 × 10−9–1.34 × 10−7 cm/s. Analysis shows that SiO2, Al2O3, and CaO in industrial calcium-containing solid wastes and sludges produce dense bulk and agglomerated C-S-H and C-A-S-H gels under alkali excitation. The optimum ratio of sludge, desulfurized gypsum, fly ash, and slag in the solidified sludge was 1:0.61:0.62:0.54, whereas the optimum exciter was Ca(OH)2. The SSM may be used as a good barrier material to prevent water seepage in landfills.

Effect of salt permeants on the consolidation and hydraulic behaviour of fibre treated black cotton soil for landfill application

Clay liner functions as an impermeable barrier between leachate and groundwater in landfills. In this work, naturally available black cotton (BC) soil is adopted as a liner material due to its high swelling and low hydraulic conductivity, which helps to eliminate the risk of groundwater pollution by preventing pollutant mobility. The liner's potential is threatened by two issues: shrinkage cracks and chemical attacks. BC soil induces desiccation cracks and high compressibility due to its high shrinkage potential upon drying, which severely impacts its hydraulic conductivity behaviour. In recent years, fibres have been used as reinforcing materials to control compressibility and shrinkage cracks of the liner. In this investigation, waste tire fibres, which were used as a reinforcing material, mixed with BC soil in the proportion of 5, 10 and 15% by their dry weight. Since the essential parameters of liner would change due to the interaction of chemicals in leachate, hence, this study examined the consolidation and hydraulic properties of fibre mixed BC soil in the presence of two inorganic salt permeants (NaCl and CaCl2) of two concentrations (0.1 and 1N) to mimic the leachate effect. The results revealed that when salt solutions were utilised as saturating pore liquids, the time to achieve the 90% of consolidation (t90) of fibre-treated BC soil was decreased, thereby increasing the coefficient of consolidation (cv). These changes were more significant at higher concentrations of pore liquids. The t90 value for 15% fibre-treated soil with DI water is 27.0 min, and it decreased drastically to 0.8 min (97.0% reduction) for 1N NaCl solution and 0.6 min (97.8% reduction) for 1N CaCl2 solution at the higher consolidation pressure of 784.5 kPa. Compression index (Cc) and void ratio (e) were reduced with the salt permeants irrespective of the fibre content. Finally, it was shown that salts substantially impact the hydraulic conductivity values of fibre-treated soil and that up to 10% fibre content is appropriate for landfill liner application.

Snowmelt-Driven Seasonal Infiltration and Flow in the Upper Critical Zone, Niwot Ridge (Colorado), USA

The hydrology of alpine and subalpine areas in the Colorado Front Range (USA) is evolving, driven by warming and by the alteration of precipitation patterns, the timing of snowmelt, and other components of the hydrologic budget. Field measurements of soil hydraulic conductivity and moisture along 30-m transects (n = 13) of representative soils developed in surficial deposits and falling head slug tests of shallow groundwater in till demonstrate that hydraulic conductivity in the soil is comparable to hydraulic conductivity values in the shallow aquifer. Soil hydraulic conductivity values were variable (medians ranged from 5.6 × 10−7 to 4.96 × 10−5 m s−1) and increased in alpine areas underlain by periglacial deposits. Hydraulic conductivities measured by a modified Hvorslev technique in test wells ranged from 4.86 × 10−7 to 1.77 × 10−4 m s−1 in subalpine till. The results suggest a gradient from higher hydraulic conductivity in alpine zones, where short travel paths through periglacial deposits support ephemeral streams and wetlands, to lower hydraulic conductivity in the till-mantled subalpine zone. In drier downstream areas, streambed infiltration contributes substantially to near-channel groundwater. As summer temperatures and evapotranspiration (ET) increase and snowmelt occur earlier, alpine soils are likely to become more vulnerable to drought, and groundwater levels in the critical zone may lower, affecting the connectivity between late-melting snow, meltwater streams, and the areas they affect downstream.

Physiological trait networks enhance understanding of crop growth and water use in contrasting environments.

Plant function arises from a complex network of structural and physiological traits. Explicit representation of these traits, as well as their connections with other biophysical processes, is required to advance our understanding of plant-soil-climate interactions. We used the Terrestrial Regional Ecosystem Exchange Simulator (TREES) to evaluate physiological trait networks in maize. Net primary productivity (NPP) and grain yield were simulated across five contrasting climate scenarios. Simulations achieving high NPP and grain yield in high precipitation environments featured trait networks conferring high water use strategies: deep roots, high stomatal conductance at low water potential ("risky" stomatal regulation), high xylem hydraulic conductivity and high maximal leaf area index. In contrast, high NPP and grain yield was achieved in dry environments with low late-season precipitation via water conserving trait networks: deep roots, high embolism resistance and low stomatal conductance at low leaf water potential ("conservative" stomatal regulation). We suggest that our approach, which allows for the simultaneous evaluation of physiological traits, soil characteristics and their interactions (i.e., networks), has potential to improve our understanding of crop performance in different environments. In contrast, evaluating single traits in isolation of other coordinated traits does not appear to be an effective strategy for predicting plant performance.

Numerical modeling of NE Brazil coastal aquifer: Fault controlled conduits for seawater intrusion

Saline intrusion is a problem that mostly affects coastal aquifers around the world, either owing to anthropic and/or natural factors. The Barreiras Aquifer, which is located on Brazil's northeastern coast and of an unconfined hydraulic nature, is subject to this due to a water demand increase. This aquifer is located in an area structurally controlled by neotectonic activity. Increased complexity occurs in the form of variations in saturated thickness, hydraulic conductivity and exploited flow rates. This study aimed to construct a numerical model of dependent density flow for the Barreiras Aquifer using the SEAWAT software (USGS) and simulate saline intrusion over 20 years of pumping wells that currently exploit approximately 750 m³/h. The results can contribute to local hydrogeological management and assist managers. Simulation results with variation of recharge between dry and rainy periods and reduction of well exploitation flow rates were also obtained. The two main local faults, Boa Cica and Tabatinga, striking NW-SE and NE-SW, respectively, were simulated in a calibrated transient hydrogeological model as zones of high hydraulic conductivity (conduits) as well as in the inverse form (barriers) and offered a better fit considering the faults as zones of relatively higher hydraulic conductivities and preferred pathways for saltwater intrusion progression. A two-dimensional resistivity cross-section was used to constrain the electrical property of the NW striking fault, whether in the form of a resistive anomaly or conductive anomaly. The interpretation of the 2D geoelectric model is consistent with the conductive geoelectric anomaly associated to the Boa Cica Fault, where its transtensional nature favors wider saline contamination.

Hydrological simulation and assessment of the optimal parameters of the water replenishment of the floodplain lake and old riverbed on the Uzh river

One of the tasks in modern approach of the water resources management is improving environment health by the way of the river restoration. On the urban area it is impossible to provide full river restoration, but at the same time it is possible to create the environment close to natural. In our work on the example of the river Uzh located inside the city provides the assessment of the restoring possibility of the part of the floodplain by water replenishment of the old riverbed during the vegetation season. Flood control dyke construction interrupted the connection between old riverbed and river and as a result floodplain lake became muddy, silted up and lost its attractive form. To assess the possibility of the floodplain lake replenishment, the simulation of some scenarios were carried out: natural condition, water replenishment during flood, pumping water, raising water level in the river Uzh near the lake. The connection of the lake and the old riverbed with the river will improve slightly the storage capacity of the lake and allows to provide the depth of up to 1.0 m in the lake during flood, but the water will be absent in the old riverbed during the dry season. Hydraulic calculation showed that replenishment during spring floods and pumping water were not possible due to high hydraulic conductivity of the gravel and pebble soils. The old riverbed replenishment is possible by raising water level in the river Uzh, which will ensure the free water flow into the lake and into the old riverbed during the dry season.

Impacts of anthropogenic groundwater recharge (AGR) on nitrate dynamics in a phreatic aquifer revealed by hydrochemical and isotopic technologies

Although anthropogenic groundwater recharge (AGR) can either elevate or decline the concentration of nitrate in the phreatic aquifer with high hydraulic conductivity, the long-term impact of AGR on nitrate dynamics in the phreatic aquifer and its reason is seldom disclosed. In this study, the hydrogen and oxygen stable isotopes (δ2H-H2O and δ18O-H2O) combined with mixing stable isotope analysis in R (MixSIAR) were used to group the study area into the dominant area of AGR by surface water (AGRSW) and the dominant area of natural groundwater recharged by precipitation (NGRP). Hydrochemical parameters and multiple stable isotopes, including δ2H-H2O, δ18O-H2O, δ15N-NO3−, δ18O-NO3−, and δ13C-DIC, were applied to explore the impacts of AGR on the concentration, biogeochemical processes, and main sources of nitrate. The results showed that AGR by surface water with low nitrate content can reduce nitrate pollution in groundwater. The characteristic of δ18O-NO3− value revealed that nitrification was the primary biogeochemical process of nitrogen in groundwater. AGR may enhance nitrification as indicated by the δ18O-NO3− value closer to the nitrification theoretical line. Dual nitrate stable isotopes and MixSIAR revealed that chemical fertilizer (CF), soil nitrogen (SN), and surface water (SW) contributed 10.88%, 49.92%, and 27.64% to nitrate in AGRSW groundwater, respectively, which was significantly different from their contributions to NGRP groundwater (p < 0.05). Notably, AGR significantly increased the contribution of SW but decreased the contribution of CF and SN in groundwater. This study provided a basis and guidance for groundwater quality assessment and pollution control in the phreatic aquifer with high hydraulic conductivity.