Water Table Level Research Articles

Data sets for the Upper Penticton Creek watershed experiment: A paired‐catchment study to support investigations of watershed response to forest dynamics and climatic variability in an inland snow‐dominated region

AbstractThe Upper Penticton Creek watershed experiment is one of a handful of forestry‐focused paired catchment experiments in the snow‐dominated zone of western North America. The study involves an undisturbed control catchment and two treatment catchments. Streamflow has been monitored at weirs on all three streams since 1985. Following a pre‐harvest monitoring period, the treatment catchments were subject to clearcut harvesting in multiple passes that cumulatively covered ~50% of the catchments. In addition to streamflow, available hydrometeorological data sets include weather observations, snowpack water equivalent, rainfall interception, soil water content and water table levels in soil piezometers and bedrock wells. The data archive also includes digital elevation models, a Lidar‐derived image of tree heights in 2016, and vector data associated with lakes and reservoirs, the stream network, clearcut boundaries, a soil map and the logging road network. Together, these data sets provide a basis for empirical analyses of hydrological response to forest dynamics and climatic variability, and for calibration and testing hydrological models using internal variables. They should also provide useful data sets for educational purposes.Novelty StatementUpper Penticton Creek is the only long‐term, snowmelt‐dominated, experimental paired catchment study in western Canada and one of only a few in western North America. Four decades of environmental monitoring and research at this site provide an important data set to support analysis and modelling of hydrologica response to forest disturbance and climatic variability.

Karst and tunnelling: a reverse impact case history

In this paper we present a case history in which tunneling heavily impacted onto a karst system. This paper deal with a hydraulic tunnel under pressure crossing a mountain ridge constituted by calcareous and gypsum units, karstfied in recent geological time. The tunnel was driven right above the water table, and above the base level of karstification, in the transfer zone. During time, the concrete lining suffered deterioration mainly due to cavitation processes that led to pierce the lin-ing and the water flowing from the tunnel into the surrounding rock-mass. The water pressure into the tunnel changes daily, according to the needs, from 400 to 600 kPa. That led to inflowing water into the karstfied rock-mass creating a bub-ble of water infilling the karst system tubes and conduits above the tunnel for a highness of 40 m to 60 m and asymmetric shaped to the lower end of the moun-tain ridge and its sides. Therefore, many springs at higher level of the natural wa-ter table were activated and the base water flow in the karst emerging springs largely improved. When for the execution of the remedial works the tunnel was empty a surplus of water flow of about 6 Mm3 was recorded, all this water was drained from the water bubble created into the karst system. Once the tunnel had been cladded by a steel tube and the water flow reopened no more water losses occurred.

Analysis of surface water utilization for restoration of the groundwater table case study: Dayeuhkolot, Bandung-Soreang groundwater basin

Groundwater utilization as a source of clean water for the community increases, both for domestic and non-domestic needs, thus lowering the groundwater table. The Dayeuhkolot area is part of the Bandung-Soreang Groundwater Basin, which has a groundwater table decline resulting from excessive groundwater utilization. The Experimental Station of Groundwater modeled the groundwater condition in 2010-2020 concluded that the groundwater decline for a particular area reaches up to 50 m. This study aims to analyze the potential for groundwater table restoration that can be carried out at the research location by reducing groundwater utilization through the substitution of surface water use. The prospect of surface water that can be utilized can be identified by identifying its quantity and quality for the feasibility of using surface water as a substitute for groundwater utilization to implement the concept of conjunctive use. Groundwater modeling is carried out with a substitution scheme for groundwater utilization with surface water. Modeling results show that the reduction in groundwater utilization positively impacts the restoration of the water table level. Based on the model result, the groundwater level can recover as high as 2.37 m from 2020 conditions.

Integrated Duflow-Drainmod model for planning of water management operation in tidal lowland reclamation areas

The research objective was to develop field operational model to control water table level at reclaimed area of tidal lowland for food crop cultivation. DUFLOW computer model was used to evaluate the perfomance of water management network at secondary and tertiary levels, whereas DRAINMOD computer model is used to evaluate soil water status at tertiary block. Results of DUFLOW model simulation can be used to improve water management by passing the Secondary Irrigation Chanel (SPD) and Secondary Drainage Chanel (SDU) through tertiary channels, water gate installation of stop-log type and weir construction in Drainage Secondary Channel (SDU). The weir construction has function as long storage and capable to control or maintain soil water level in land not quickly drawdown. Drainmod simulation model is acceptable, this is indicated by the results of statistical analysis where the correlation coefficient value reaches 0.89. Analysis of DUFLOW-DRAINMOD computer model software showed mutually supportive results in which DUFLOW simulation results can provide water potential information in channel for supply purpose. This water level condition is an important part in DRAINMOD model because it has effect on soil water level dynamics as targeted on tertiary block as well as on capacity to applied drainage operation system.

Long-term spatiotemporal evolution of land subsidence in Konya metropolitan area (Turkey) based on multisensor SAR data

We have studied the spatiotemporal evolution of surface deformation in Konya city and its vicinity using advanced multitemporal synthetic aperture radar techniques with SAR data acquired by Envisat, ALOS-1, and Sentinel-1 A/B satellites between 2004 and 2020. Velocity maps and time series show that the city has been subsiding with varying rates in space and time since 2004. The pattern of deformation shows two main lobes of subsidence centered in the western and eastern sides of the city with a nondeforming north-south trending narrow zone in between. Subsidence rate increases from a few cm/yr to 11 cm/yr between 2014 and 2019. As of 2019, subsidence has slowed down dramatically, giving rise to uplift in some places. Spatiotemporal variation of subsidence and its strong correlation with change in water table level confirm the inferences that subsidence in the metropolitan area of Konya is due to over drafting of the ground water for urban needs. The decrease in subsidence rate over the last two years appears to be due to the city?s residents supplying their water from recently built dams instead of aquifers beneath the city. Initial excessive groundwater extraction in agricultural areas caused ~4 m drops every year in the water table level, which, in turn, gave rise to 8 cm subsidence every year. Modeling of the subsidence shows 7.7 x 106 m3/yr volume loss due to compaction of the aquifer in the Konya metropolitan area and its vicinity between 2014 and 2018.

Divergent responses of wetland methane emissions to elevated atmospheric CO2 dependent on water table

Elevated atmospheric CO2 may have consequences for methane (CH4) emissions from wetlands, yet the magnitude and direction remain unpredictable, because the associated mechanisms have not been fully investigated. Here, we established an in situ macrocosm experiment to compare the effects of elevated CO2 (700 ppm) on the CH4 emissions from two wetlands: an intermittently inundated Calamagrostis angustifolia marsh and a permanently inundated Carex lasiocarpa marsh. The elevated CO2 increased CH4 emissions by 27.6–57.6% in the C. angustifolia marsh, compared to a reduction of 18.7–23.5% in the C. lasiocarpa marsh. The CO2-induced increase in CH4 emissions from the C. angustifolia marsh was paralleled with (1) increased dissolved organic carbon (DOC) released from plant photosynthesis and (2) reduced (rate of) CH4 oxidation due to a putative shift in methanotrophic community composition. In contrast, the CO2-induced decrease in CH4 emissions from the C. lasiocarpa marsh was associated with the increases in soil redox potential and pmoA gene abundance. We synthesized data from worldwide wetland ecosystems, and found that the responses of CH4 emissions to elevated CO2 was determined by the wetland water table levels and associated plant oxygen secretion capacity. In conditions with elevated CO2, plants with a high oxygen secretion capacity suppress CH4 emissions while plants with low oxygen secretion capacity stimulate CH4 emissions; both effects are mediated via a feedback loop involving shifts in activities of methanogens and methanotrophs.

Liquefaction potential for the Kathmandu Valley, Nepal: a sensitivity study

An assessment of liquefaction potential for the Kathmandu Valley considering seasonal variability of the groundwater table has been conducted. To gain deeper understanding seven historical liquefaction records located adjacent to borehole datapoints (published in SAFER/GEO-591) were used to compare two methods for the estimation of liquefaction potential. Standard Penetration Test (SPT) blowcount data from 75 boreholes inform the new liquefaction potential maps. Various scenarios were modelled, i.e., seasonal variation of the groundwater table and peak ground acceleration. Ordinary kriging, implemented in ArcGIS, was used to prepare maps at urban scale. Liquefaction potential calculations using the methodology from (Sonmez, Environ Geol 44:862–871, 2003) provided a good match to the historical liquefaction records in the region. Seasonal variation of the groundwater table is shown to have a significant effect on the spatial distribution of calculated liquefaction potential across the valley. The less than anticipated liquefaction manifestations due to the Gorkha earthquake are possibly due to the seasonal water table level.

Coastal flooding generated by ocean wave- and surge-driven groundwater fluctuations on a sandy barrier island

Three years of observations of groundwater elevations, ocean tides, surge, and waves, and rainfall are used to study coastal groundwater-driven flooding along the ocean side of a barrier island. Increases in surge and wave-driven water levels (setup) during 26 ocean storms with little rainfall, including the passage of 3 hurricanes, caused O(1 m) increases in groundwater heads under the dunes on the ocean side of the island, nearly double previously reported magnitudes. The inland propagation of the resulting pulses in groundwater levels is consistent with an analytical model (without recharge) based on shallow aquifer theory (Nash Sutcliffe model efficiencies of >0.7, maximum water-table level estimates within 0.1 m of observations). Infiltration of precipitation results in approximately a threefold increase in the groundwater level relative to the amount of rainfall. The analytical model (with recharge) driven with estimated ocean shoreline water levels (based on the 36-hr-averaged offshore tide, surge, and wave height) and measured precipitation predicts the maximum water-table height within 0.15 m of that observed across the barrier island during Hurricane Matthew, which was the only wave event during the 3-yr data set with more than 0.1 m rainfall.Citizen-science reports from a smartphone app (iFlood) are used to evaluate the regional application of the model. Twenty-five ocean-side reports associated with 7 ocean storms (6 of which had minimal rainfall) between Sept 2019 and Feb 2020 showed flooding on natural (permeable) land surfaces along 70 km of the northern Outer Banks barrier island, from Corolla to Rodanthe, NC. The analytical model (with recharge) predicts flooding that is consistent with the timing and location for 19 of the 25 reports. Applying the model regionally suggests that more than 10% of the land area on the ocean side of the northern Outer Banks would be inundated by coastal groundwater even in the absence of rainfall for an ocean storm that generates a 2.25 m increase in the shoreline water level.

Peatland microbial community responses to plant functional group and drought are depth-dependent.

Peatlands store one-third of Earth's soil carbon, the stability of which is uncertain due to climate change-driven shifts in hydrology and vegetation, and consequent impacts on microbial communities that mediate decomposition. Peatland carbon cycling varies over steep physicochemical gradients characterizing vertical peat profiles. However, it is unclear how drought-mediated changes in plant functional groups (PFGs) and water table (WT) levels affect microbial communities at different depths. We combined a multiyear mesocosm experiment with community sequencing across a 70-cm depth gradient, to test the hypotheses that vascular PFGs (Ericaceae vs. sedges) and WT (high vs. low) structure peatland microbial communities in depth-dependent ways. Several key results emerged. (i) Both fungal and prokaryote (bacteria and archaea) community structure shifted with WT and PFG manipulation, but fungi were much more sensitive to PFG whereas prokaryotes were much more sensitive to WT. (ii) PFG effects were largely driven by Ericaceae, although sedge effects were evident in specific cases (e.g., methanotrophs). (iii) Treatment effects varied with depth: the influence of PFG was strongest in shallow peat (0-10, 10-20cm), whereas WT effects were strongest at the surface and middle depths (0-10, 30-40cm), and all treatment effects waned in the deepest peat (60-70cm). Our results underline the depth-dependent and taxon-specific ways that plant communities and hydrologic variability shape peatland microbial communities, pointing to the importance of understanding how these factors integrate across soil profiles when examining peatland responses to climate change.

Fine‐scale hydrological niche segregation in coastal dune slacks

AbstractQuestionsHydrological niche segregation is widespread and has been found across a range of different habitats. Different plant species can occupy distinct hydrological niches, and as a result fine‐scale variability in hydrology can structure plant communities. However, these patterns may not be as clear in habitats where differences in hydrology are more short‐lived, such as coastal dune slacks. We explored the extent that the hydrological regime structures dune slack plant communities.LocationAinsdale Coastal Sand Dune National Nature Reserve, UK.MethodsSix hundred quadrats were surveyed, 100 in each of six coastal dune slacks. Water table levels are recorded monthly in each slack. Metrics summarising hydrological regime were calculated and adjusted for each quadrat based on elevation. We tested the relationship between water table depth, plant communities and topography across and within dune slacks.ResultsHalf (three) of the slacks showed a significant influence of hydrology on plant community composition. The three that did not were the ones that varied least topographically and contained less diverse plant communities. We also provide indirect evidence of niche segregation by modelling species‐specific responses between mean water table depth and probability of species presence.ConclusionsWe demonstrate that hydrology is a dominant driver of plant community composition across dune slacks. However, plant communities are not always structured by hydrology, demonstrating the complexity of vegetation patterns. Topographic variation appears to impact plant community patterns, as do successional processes, highlighting the need to create diverse habitats for slack restoration and management.

Carbon emissions from a temperate coastal peatland wildfire: contributions from natural plant communities and organic soils

BackgroundOne of the scientific challenges of understanding climate change has been determining the important drivers and metrics of global carbon (C) emissions and C cycling in tropical, subtropical, boreal, subarctic, and temperate peatlands. Peatlands account for 3% of global land cover, yet contain a major reservoir of 550 gigatons (Gt) of soil C, and serve as C sinks for 0.37 Gt of carbon dioxide (CO2) a year. In the United States, temperate peatlands are estimated to store 455 petagrams of C (PgC). There has been increasing interest in the role of wildfires in C cycling and altering peatlands from C sinks to major C sources. We estimated above- and below-ground C emissions from the Pains Bay Fire, a long-duration wildfire (112 days; 18,329 ha) that burned a coastal peatland in eastern North Carolina, USA.ResultsSoil C emissions were estimated from pre- and post-burn Light Detection and Ranging (LIDAR) soil elevation data, soils series and C content mapping, remotely sensed soil burn severity, and post-burn field surveys of soil elevation. Total above-ground C emissions from the fire were 2,89,579 t C and 214 t C ha−1 for the 10 vegetation associations within the burn area perimeter. Above-ground sources of C emissions were comprised of litter (69,656 t C), shrub (1,68,983 t C), and foliage (50,940 t C). Total mean below-ground C emissions were 5,237,521 t C, and ranged from 2,630,529 to 8,287,900 t C, depending on organic matter content of different soil horizons within each of the 7 soil series. The mean below-ground C emissions within the burn area were 1,595.6 t C ha−1 and ranged from 629.3 to 2511.3 t C ha−1.ConclusionsIn contrast to undisturbed temperate peatlands, human induced disturbances of the natural elevation gradient of the peatland has resulted in increased heterogeneity of floristic variation and assemblages that are a product of the spatial and temporal patterns of the water table level and the surface wetness across peatlands. Human induced changes in surface hydrology and land use influenced the fuel characteristics of natural vegetation and associated soils, thus influencing wildfire risk, behavior, and the resulting C emissions.

MONITORING OF LAND DEGRADATION AND SOIL PRODUCTIVITY IN BILQAS DISTRICT, DAKAHLIA GOVERNORATE, EGYPT

Soil degradation is one of the most important obstacles to agricultural development. In the past few years, there has been interest from research agencies and relevant ministries to control soil degradation in the Egyptian lands. This study aims to assess soil degradation , soil productivity and the correlation coefficient between them in Bilqas District, Dakahlia Governorate. To achieve this goal, soil data for the study area were taken from a previous study (2010) and compared with soil data for the study area at the present time. Two main physiographic units dominate the study area i.e. Aeolian plain (Coarse texture) and Flood plain (Moderately fine to fine texture). Depending on these physiographic units, the study area was divided into different types of landforms, sixteen soil profiles were selected to represent these types of landforms. The soil profile locations examined by the current study were the same as the soil profile locations for the previous study.Soil degradation status was assessed; the results indicate that the most active soil degradation processes are salinity, waterlogging and alkalinity. After evaluating the soil productivity, it was found that its productivity indexes were decreased in most of soil profiles, while it was stable in some profiles and increased in few profiles. There was correlation coefficient between soil productivity and water table level , salinity and alkalinity.

Multivariate Analysis Applied to Aquifer Hydrogeochemical Evaluation: A Case Study in the Coastal Significant Subterranean Water Body between “Cecina River and San Vincenzo”, Tuscany (Italy)

The hydrogeochemical characteristics of the significant subterranean water body between “Cecina River and San Vincenzo” (Italy) was evaluated using multivariate statistical analysis methods, like principal component analysis and self-organizing maps (SOMs), with the objective to study the spatiotemporal relationships of the aquifer. The dataset used consisted of the chemical composition of groundwater samples collected between 2010 and 2018 at 16 wells distributed across the whole aquifer. For these wells, all major ions were determined. A self-organizing map of 4 × 8 was constructed to evaluate spatiotemporal changes in the water body. After SOM clustering, we obtained three clusters that successfully grouped all data with similar chemical characteristics. These clusters can be viewed to reflect the presence of three water types: (i) Cluster 1: low salinity/mixed waters; (ii) Cluster 2: high salinity waters; and (iii) Cluster 3: low salinity/fresh waters. Results showed that the major ions had the greater influence over the groundwater chemistry, and the difference in their concentrations allowed the definition of three clusters among the obtained SOM. Temporal changes in cluster assignment were only observed in two wells, located in areas more susceptible to changes in the water table levels, and therefore, hydrodynamic conditions. The result of the SOM clustering was also displayed using the classical hydrochemical approach of the Piper plot. It was observed that these changes were not as easily identified when the raw data were used. The spatial display of the clustering results, allowed the evaluation in a hydrogeological context in a quick and cost-effective way. Thus, our approach can be used to quickly analyze large datasets, suggest recharge areas, and recognize spatiotemporal patterns.

Identifying the full spectrum of climatic signals controlling a tree species' growth and adaptation to climate change

Identifying the key climatic parameters controlling a tree species’ growth in a given environment can improve our understanding of the species’ adaptability to climate change. However, this can be significantly affected by the detection and analytical methodologies used, at least for water-limited ecosystems. To address this issue, we tested together for the first time the five key methods widely applied for detecting climatic drivers of tree growth. The test was applied on the growth dynamics of Pinus pinea L. (the last ca. 130 years) and for evaluating its climatic sensitivity (the last ca. 60 years), under contrasting climatic conditions, from sites in Italy and Greece. As predictors, we selected a high number of seasonal, annual, and multi-annual climate integration periods (626 variables in total for precipitation and SPEI) through running correlation analysis. Methods that retain low-frequency variability and persistence of past climatic signals in radial growth (ABD, RCS, and raw BAI) revealed that long-term precipitation accumulated over 3–6 years was the key driver for P. pinea growth in the wettest sites. These signals probably appeared because of the cumulative effects of past years’ rainfall in determining water table levels. They would have been missed if low-frequency climate and growth variability were not considered, how it happens using standardized BAI and TRW. In the driest site, productivity was low and explained by 1–2 years precipitation signals, suggesting that mostly moisture stored in topsoil from more recent rainfall sustained P. pinea growth, a typical shallow-rooted species. Thus, the loss in root contact with the declining water table may explain the higher vulnerability to drought stress at its dry-end distribution range, particularly under low precipitation. A further drop in water table levels, driven by global warming, will most likely increase such vulnerability. Hence, conservation efforts will require maintaining a stable water table, prohibiting groundwater overexploitation at P. pinea habitats. Reducing competition from other deeper rooted tree species, better adapted to drought and fire, may further benefit the species’ conservation status.

Preferential solute transport under variably saturated conditions in a silty loam soil: Is the shallow water table a driving factor?

A shallow water table might enhance preferential solute movement by modifying both the water flow and solute dynamics. In this study, we estimated soil hydraulic and solute transport parameters through a tracer experiment in lysimeters comparing different water table levels. In a set-up of 12 lysimeters, the bottom boundary condition was set as a water table depth of 120 cm, or 60 cm, or as free drainage. A tracer solution of bromide (250 mg l−1, 40 mm) was added to each lysimeter and soil water was sampled with suction cups at different depths for the following 174 days. Soil water content and matric potential were monitored using TDR probes and electronic tensiometers at the same depths. Soil hydraulic and solute transport parameters in different soil layers were estimated by inverse modeling using HYDRUS 1D. Soil hydraulic parameters were estimated from the Mualem-van Genuchten equations, while both the advection–dispersion (ADE) and physical non-equilibrium mobile-immobile water (MIM) models were used to describe the solute transport. Moreover, the soil pore network was analyzed by means of 3D X-ray microtomography. Results showed different solute dynamics between contrasting water table managements. With free drainage, solute in the immobile domain was negligible, and its transport was fully associated with the mobile water flow. In contrast, a shallow water table affected the tracer transport, by modifying a) the soil pore network, with an increase of the macropores and a reduction of the pore connectivity; b) the flow field, with an increase of immobile water and a reduction of αMIM, indicating slow exchange between mobile and immobile regions, in turn promoting preferential pathways. Hence, groundwater pollution might be worsened by preferential solute transport of agrochemicals occurring with shallow water table conditions.

Assessing response times of an alluvial aquifer experiencing seasonally variable meteorological inputs

This study aims to assess the spatiotemporal distribution of the response times of an alluvial aquifer experiencing seasonally variable meteorological inputs and to investigate the aquifer characteristics that influence its response times. The sliding cross-correlogram approach was used in this study to correlate the amount of water infiltrating the subsurface with changes in water table levels that were monitored at six piezometers. The results showed a significant variation of aquifer response times over the study area; this finding indicates that the hydraulic behavior of an aquifer may differ from one location to another within the same aquifer. Aquifer response times were found to be influenced by the variations of the vadose zone thickness. These variations, however, were not observed to be a significant factor controlling the spatiotemporal changes in the aquifer response times. Instead, it was the intensity of the vertical inflow events and the local recharge rate that were found to exert an impact on the spatiotemporal variation of the aquifer response times. It was assumed that large amounts of vertical inflow increase the soil's volumetric water content above the water table, leading to higher values of hydraulic conductivity of unsaturated soils, thus contributing to shortening aquifer response times. A better understanding of the effects of aquifer characteristics on aquifer response times is useful for groundwater resource management.

Improving our ability to model crystalline aquifers using field data combined with a regionalized approach for estimating the hydraulic conductivity field

Modelling of heterogeneous aquifers, such as crystalline aquifers, is often difficult and, flow and transport predictions are always uncertain, suffering of our imperfect knowledge of the spatial distribution of aquifer parameters. This paper aims to test the robustness of a first-order hydraulic conductivity map estimated from both a detailed water-table map and hydraulic-conductivity statistics on a granitic watershed in Brittany (57 km2), compare it to local estimates and assess it through various numerical models. Map values range on four orders of magnitude (10-7 to 10-4 m/s, mean: 3.9x10-6 m/s) and their comparison to local estimates from various sources (pumping tests, MRS measurements, streamflow) gives satisfactory results.Four hydraulic conductivity fields were assessed through numerical modelling under steady-state condition. Model 1 used the regionalized hydraulic conductivity field directly, Model 2 used a uniform value (average of Model 1), Model 3 used a hydraulic conductivity field obtained by inverse modelling of the water table and Model 4 used two zones of uniform values based on the analysis of Model 1 and Model 3 fields. Model results were analysed based on their ability to reproduce the observed water-table levels and the groundwater flow directions. Modelled groundwater discharges to streams at sub-catchment scale were compared to spatial streamflow measurements performed during low water condition, which help validating models. The comparison between the fields obtained from Model 3 and that from the regionalized method (Model 1) shows that they are close in terms of mean values and spatial distribution. Model 1 reproduces rather well the water-table map and the groundwater flow directions. Model 2 shows the less good results. Model 4 has led to satisfactory results and shows that the hydraulic conductivity is higher (2.1x10-6 m/s) where the water table is located in the fractured zone, and lower (3.3x10-7 m/s) where it is located in the saprolites (highly weathered rock), which is expected for such aquifer system. Modelled groundwater discharges to streams are comparable in all models to streamflow measurements in most sub-catchments, but the models overestimate them in certain places, mainly because of sub-surface drains in a forest capturing part of the groundwater that can no longer return to streams (drains were not considered in the models).In addition, experiment on a second watershed (40 km2) shows how with much less field data the methodology can already provide interesting information on the hydraulic conductivity field (values and spatial distribution).Results are very encouraging and open up prospects for using quantitative and qualitative information from the mapping of hydraulic conductivity to constrain the spatialization of hydrodynamic parameters on models and thus our ability to model such complex aquifers.

Freshwater–Saltwater Interactions in a Multilayer Coastal Aquifer (Ostia Antica Archaeological Park, Central ITALY)

An integrated research approach consisting of hydrogeologic and geochemical methods was applied to a coastal aquifer in the Ostia Antica archaeological park, Roma, Italy, to describe freshwater–saltwater interactions. The archaeological park of Ostia Antica is located on the left bank of the Tevere River delta which developed on a morphologically depressed area. The water monitoring program included the installation of multiparametric probes in some wells inside the archaeological area, with continuous measurement of temperature, electrical conductivity, and water table level. Field surveys, water sampling, and major elements and bromide analyses were carried out on a seasonal basis in 2016. In order to understand the detailed stratigraphic setting of the area, three surface boreholes were accomplished. Two distinct circulations were identified during the dry season, with local interaction in the rainy period: an upper one within the archaeological cover, less saline and with recharge inland; and a deeper one in the alluvial materials of Tevere River, affected by salinization. Oxygen and carbon isotopic signature of calcite in the sediments extracted from the boreholes, along with major elements and Br concentration, allowed us to recognize the sources of salinity (mainly, local interaction with Roman salt pans and agricultural practices) and the processes of gas–water–rock interaction occurring in the area. All these inferences were confirmed and strengthened by PCA analysis of physicochemical data of groundwater.

Groundwater Single- and Multiobjective Optimization Using Harris Hawks and Multiobjective Billiards-Inspired Algorithm

This is the first attempt to combine the Multiobjective Billiards-Inspired Optimization Algorithm (MOBOA) with groundwater modelling to determine pumping rates within a well-distributed range of Pareto options. In this study, in order to determine an optimum solution for groundwater drawdown, pumping rates were selected accompanied by three minimization objectives: minimizing shortage influenced by inability to supply, adjusted shortage index, and minimizing the degree of drawdown within predefined areas. To optimize hydraulic conductivity and specific yield parameters of a modular three-dimensional finite-difference (MODFLOW) groundwater model, the Harris Hawks optimization algorithm was used to minimize the sum of absolute deviation between observed and simulated water-table levels. MOBOA was then utilized to optimize pumping rate variables for an Iranian arid to semiarid groundwater environment using these parameters. As the study results, when the maximum and minimum aquifer drawdown was specified in the range of −40 to +40 cm/year, the Pareto parameter sets produced satisfactory results. Overall, the “Simulation-Optimization-Modelling” protocol was able to generate a series of optimal solutions that were shown on a Pareto front. The study concluded to an optimum approach that provides policy makers in the Iranian water stressed zones with safe groundwater management alternatives.

Simulation modelling of greenhouse gas balance in continuous-cover forestry of Norway spruce stands on nutrient-rich drained peatlands

We used a simulation model to analyse the effect of continuous-cover forestry on the carbon dioxide (CO2) and methane (CH4) emissions from nutrient-rich drained peatland sites in southern Finland. The simulation scenarios were constructed by varying harvesting interval and post-harvest basal area in a typical mature Norway spruce (Picea abies (L.) H. Karst.) stand. A process-based model of soil organic matter dynamics supplied with some additional empirical routines was used for calculation of emission due to decomposition of fresh litter and peat. The amount and chemical properties of litter inputs, as well as the hydrothermal conditions and the water table depth in the peat layer were used as predictors. We estimated the net ecosystem production as a difference between carbon sequestration in stand biomass and carbon losses due to decomposition of dead organic matter, and the net biome production as the net primary production minus losses due to harvesting. Simulations showed that the peatland forest acted as a carbon sink with low and middle harvest intensity, while it turned into a carbon source with high harvesting intensities. This was mostly because intensive harvesting raised the water table level, thus decreasing tree production and increasing soil methane emission. Carbon dioxide emissions from peat and litter, in turn, correlated negatively with the intensity of harvesting. Correlation of site carbon balance with harvested roundwood indicated that there is a significant trade-off between maintaining carbon in drained peatland forests and providing harvest revenues. The simulations provide novel results and fill a gap of knowledge in ecosystem responses to alternative management regimes in continuous-cover forestry on drained peatlands.