Displays

This work describes a project that aims to assess and forecast the groundwater balance and the spatiotemporal behavior of fluxes in a regional aquifer located in the middle-high venetian plain between rivers Brenta and Piave (Italy) to analyze the impact of future irrigation policies and to define at regional scale the risk of contamination.

The area is widely exploited for agricultural purposes and over time many wells (owned by Water Service Companies and private bodies) have been drilled for the supply of drinking water. A dense network of ditches, that still guarantee most agricultural requirements by border irrigation, is replaced year by year with pressurized systems (sprinkler and drip). This change shows positive effects, reducing the amount of diverted water from rivers helping the Ecological Flows (Eflows) requirements (EU Guidance Document No. 31 2015). On the other hand, it actually reduces the infiltrated volumes (acting as artificial recharge) that sustain the groundwater reserve since centuries ago. Together with the growing number of active and potential sources of pollution, all this jeopardizes the water supply from wells intended for human consumption.

This situation requires proper knowledge and tools to anticipate consequences of a changing environment and to suggest policies for an appropriate management and sustainable use of groundwater.

The study area develops north to south from the Prealps to the middle of the plain, between Brenta River (west) and Piave River (east). Evidences from geological surveys show a sand and gravel aquifer extending from uplands in the north piedmont region to the southern one where a layered system of nine aquifers can be recognized. The hypothetical separation takes place along alluvial springs that origin the river Sile, that acts as a drain for the upper aquifer of the whole area.

A numerical model of the aquifer is under development using Feflow® by DHI, a finite element software able to reproduce the subsurface flow field and transport phenomena. Geological description and vertical stratigraphy of boreholes were used to build the geo-structural model, whose spatial extent was also chosen on the availability of data – water table, piezometric levels and/or fluxes – to be imposed on the boundaries. Rainfall, irrigation, evapotranspiration and water withdrawal artificially from wells or naturally from springs, as well as the flow interchange across the section of rivers, are the external forcing varying in time and controlling the water table and piezometric levels behaviors.

Water table and piezometric level information are fundamental in the calibration of the subsurface hydraulic parameters. The actual monitoring network, that considers sensors in wells property of Regional Environmental Agency and different Water Service Companies, has been improved to mitigate its non-uniform spatial distribution instrumenting 25 new positions to reach in the whole area (about 900 km²) a total number of 84 monitored wells (density of about 1 sensor every 10 km²).

Information about historical evolution of different irrigation techniques have been gathered from the three Land Reclamation Authorities managing the investigated area to reproduce the present situation and forecast future different scenarios.

How to cite: Trentin, T., Mazzarotto, G., and Salandin, P.: Groundwater assessment for a proper management and sustainable use of the resources in the middle-high venetian plain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9978, https://doi.org/10.5194/egusphere-egu2020-9978, 2020.

Long-term unsustainable use or overexploitation of groundwater resource have led to different degree of water table declining from arid to even humid regions across the globe. The Lower Mississippi River alluvial plain (refers to MS Delta) in subtropical humid Mississippi state, is a watershed where groundwater level has declined the most in the United States. It is even worse than any states and watersheds in the arid and semiarid regions such as Mid-West and western USA. Approximately 35 million cubic meter per day of water from the alluvial aquifer in MS Delta are withdrawn for irrigation, as a result, groundwater level has declined > 6.5 m since 1970, which threaten the sustainability of irrigated agriculture in this region. Surface water as an alternative irrigation source must be taken for sustainability of irrigated agriculture in the region. The objectives of the study were to: 1) determine the total amount of available surface water resources and its temporal and spatial variation in MS Delta; 2) simulate groundwater recharge as affected by ET based and soil moisture based full irrigation schemes using all groundwater and different percentages of surface and ground water. The coupled SWAT (Soil and Water Assessment Tool)-MODFLOW (Finite Difference groundwater model) was employed. Mean annual rainfall is 1290 mm, only 31%, 40%, and 34% of annual rainfall occurred in growing season of soybean, corn and cotton, respectively. Irrigation was required in all but 12 out of 100 years in the humid region. It was estimated that each of the three major crops required irrigation of 200 mm every year over the 100-year period. 180 billion cubic meter of ground water is required each year if all of those croplands are irrigated. The average loss of groundwater was about 5 billion cubic meter every year from 1987 to 2014 in MS Delta. There is about 0.1 million ha of surface water in the MS Delta. If only 19% of those water is used for irrigation, at least 37% of groundwater can be saved in the region. Simulation estimated that the annual available stream and pond water is 11 billion cubic meter. The amounts of weekly groundwater use for irrigation that could be replaced by surface water were 46% in May, 23% in June, 21% in July, 35% in August, and 56% in September. Results revealed that the groundwater storage was decreased by 26 cm/month due to conventional irrigation in crop season. It is promising that the groundwater storage was increased by 23 cm/month, sometimes even 60 cm/month in the crop non-growing season by recharge from rainfall. The model’s simulated results suggest that using either ET or soil moisture based groundwater irrigation scheduling, along with the conjunctive use of surface water, could be a sustainable groundwater management practice in the MS Delta.

How to cite: Feng, G., Han, Y., Ouyang, Y., and Jing, W.: Sustainable management of groundwater for mitigation of declining water tables in the Mid-South United States: challenges and potential solutions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6055, https://doi.org/10.5194/egusphere-egu2020-6055, 2020.

Water storage in surface reservoirs in arid and semiarid areas is afflicted with a variety of issues such as high evaporation, eutrophication processes and exposure to contamination and accidents. Dams to capture all rare-event floods are, generally, big and expensive structures.  Artificially recharging aquifers and storing the water in the underground offer a competing alternative. In this study, hydrogeological, geological, geophysical and hydrochemical investigations were carried out to study the potentials of the eastern side of the Lower Jordan Valley for artificial recharge. The results reveal that relatively extended areas on the eastern side of the Lower Jordan Valley have the potential to accommodate large amounts of recharge water and that the impacts of artificially storing the water in aquifers are to be judged very positive compared to surface storage, especially when the amounts of available recharge water can quantitatively be accommodated in recharge facilities.  In addition, the study shows, the advantages of underground water storage compared to surface storage in dams.  The potential storage capacities in the different parts of the Lower Jordan Valley are quantified based on rechargeable aquifer volumes and porosities. The potential uses of the recharged water are also elaborated on depending on recharge and aquifer water qualities.

How to cite: Salameh, E. and Abdallat, G.: Exploration of Potential Areas for Managed Aquifer Recharge in the Eastern Lower Jordan Valley Area, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2555, https://doi.org/10.5194/egusphere-egu2020-2555, 2020.

To achieve water sustainability and a more efficient use of water we should base on the ancestral water and territory management knowledge and grained in the culture of the people, 
This article is inspired in Nature Based Solutions (NBS) for managing water availability, particularly groundwater and aquifer-related NBS that hold major un-realized potential for alleviating adverse impacts of progressive climate change, namely to increase water security/drought resilience. In some cases, more ecosystem-friendly forms of water storage, such as natural wetlands, improvements in soil moisture and more efficient recharge of groundwater, could be more sustain-able and cost-effective than traditional grey infrastructure such as dams
The core of this article is centered in the pre-Inca and Inca civilizations and how these communities have developed ingenious NBS solutions to adapt to extreme climate scenarios such as prolonged droughts, managing water resources in a holistic way and how they understand clearly the global water cycle in all the components specially groundwater.
The article is divided in three interlinked parts: 1) to sow water, by implementing ancestral aquifer recharge solutions, 2) to retain water by improve hydraulic efficiency in terms of infiltration and drainage and 3) to collect water by improve the performance of extraction in the subterranean aqueducts in arid regions.

How to cite: Ribeiro, L.: The role of ancestral groundwater techniques as nature based solutions for managing water, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5959, https://doi.org/10.5194/egusphere-egu2020-5959, 2020.

Agricultural crop yields depend largely on soil moisture conditions in the root zone. Climate change leads to more prolonged drought periods that alternate with more intensive rainfall events. With unaltered water management practices, reduced crop yield due to drought stress will increase. Therefore, both farmers and water management authorities search for opportunities to manage risks of decreasing crop yields. Available groundwater sources for irrigation purposes are increasingly under pressure due to the regional coexistence of land use functions that are critical to groundwater levels or compete for available water. At the same time, treated wastewater from industries and domestic wastewater treatment plants are quickly discharged via surface waters towards sea. Exploitation of these freshwater sources may be an effective strategy to balance regional water supply and agricultural water demand. We present results of a pilot study in a drought sensitive region in the Netherlands, concerning agricultural water supply through reuse of industrial treated wastewater. The Bavaria Beer Brewery discharges treated wastewater to the surface water. Nevertheless, neighboring farmers invest in sprinkler irrigation to maintain their crop production during drought periods. Doing so, increasing pressure is put on the regional groundwater availability. Within a pilot study, a sub-irrigation system has been installed, by using subsurface drains, interconnected through a collector drain, and connected to an inlet control pit for the treated wastewater to enter the drainage system. Sub-irrigation is a subsurface irrigation method that can be more efficient than classical, aboveground irrigation methods using sprinkler installations. Additionally, sub-irrigated water that is not used for plant transpiration recharges the groundwater. We combine both process-based modeling of the soil-plant-atmosphere system and field experiments to i) investigate the amount of water that needs to be and that can be sub-irrigated, and ii) quantify the effect on soil moisture availability and herewith reduced needs for aboveground irrigation from groundwater.

How to cite: Bartholomeus, R. P., van Huijgevoort, M. H. J., and van Loon, A.: Water in the circular economy: using recycled water for sub-irrigation purposes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8052, https://doi.org/10.5194/egusphere-egu2020-8052, 2020.

The establishment of the sources and driven-forces of groundwater nitrate pollution is of paramount importance, contributing to agro-environmental measures implementation and evaluation. High concentrations of nitrates in groundwater occur all around the world, in rich and less developed countries.

In the case of Spain, 21.5% of the wells of the groundwater quality monitoring network showed mean concentrations above the quality standard (QS) of 50 mg/l. The objectives of this work were: i) to predict the current probability of having nitrate concentrations above the QS in Andalusian groundwater bodies (Spain) using past time features, being some of them obtained from satellite observations; ii) to assess the importance of features in the prediction; iii) to evaluate different machine learning approaches (ML) and feature selection techniques (FS).

Several predictive models based on an ML algorithm, the Random Forest, were used, as well as, FS techniques. 321 nitrate samples and respective predictive features were obtained from different groundwater bodies. These predictive features were divided into three groups, regarding their focus: agricultural production (phenology); livestock pressure (excretion rates); and environmental settings (soil characteristics and texture, geomorphology, and local climate conditions). Models were trained with the features of a year [YEAR (t₀)], and then applied to new features obtained for the next year – [YEAR(t₀₊₁)], performing k-fold cross-validation. Additionally, a further prediction was carried out for a present time – [YEAR(t_0+n)], validating with an independent test. This methodology examined the use of a model, trained with previous nitrates concentrations and predictive features, for the prediction of current nitrates concentrations based on present features. Our findings showed an improvement in the predictive performance when using a wrapper with sequential search for FS when compared to the use alone of the Random Forest algorithm. Phenology features, derived from remotely sensed variables, were the most explanative features, performing better than the use of static land-use maps or vegetation index images (e.g., NDVI). They also provided much more comprehensive information, and more importantly, employing only extrinsic features of groundwater bodies.

How to cite: Cardenas-Martinez, A., Rodriguez-Galiano, V., Luque-Espinar, J. A., and Mendes, M. P.: Predictive modelling of groundwater nitrate pollution at a regional scale using machine learning and feature selection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5414, https://doi.org/10.5194/egusphere-egu2020-5414, 2020.

The increasing awareness of the importance of groundwater for ecosystems limits the possibilities for groundwater usage. In Finland, for instance, several projects aiming to establish new groundwater intakes have been stuck in legal processes for more than ten years or even decades. A typical conflict in the legal process relates to potential negative impacts of the project on protected areas, such as Natura 2000 areas, or habitats of endangered species.

Managed aquifer recharge (MAR) is one of the solutions to secure the water balance in groundwater dependent ecosystems, or to produce drinking water from artificial instead of natural groundwater. In MAR, surface water is infiltrated into the ground to add water and facilitate increased groundwater extraction in an aquifer. As the surface water quality typically differs from precipitation by a higher content of organic matter, dissolved solids, bacteria and viruses, infiltration of lake water leads to a different groundwater quality compared to natural recharge formed from precipitation.

The sustainability of MAR largely depends on an aquifer’s capacity to remove organic matter over the long term. We studied the impact of surface water infiltration on groundwater quality by using a natural lake-aquifer system as a surrogate for MAR. Natural infiltration of lake water to groundwater has been going on for millennia at our research site, providing information over a much longer time span compared to constructed infiltration sites or laboratory tests.

The groundwater flow velocity at the site was estimated with a MODFLOW based flow model. The share of lake water infiltrate in the aquifer was estimated from stable oxygen and hydrogen isotopes. Total organic carbon (TOC), dissolved organic carbon, oxygen, iron and manganese concentrations, conductivity and pH were monitored from lake and ground water. According to our measurements, the mean concentration of TOC in lake water was 3.0 mg/L (Jylhä-Ollila et al., 2020). Within the distance of 3 m from the lake bank (retention time 7–15 days), already 46% of TOC was removed. At greater distances along the main flowpath in the aquifer, 80–90% of TOC was removed. Signs of organic matter accumulation in the aquifer were not observed, which is positive in terms of long term sustainability of MAR. Several processes had an impact on oxygen levels in the aquifer, which led to spatial and seasonal changes in the redox conditions and in the iron and manganese concentrations in groundwater. The results showed that an aquifer can remove organic matter from surface water over a long time span, but possible oxygen depletion and iron and manganese release should be taken into account in MAR projects aiming to secure groundwater dependent ecosystems.

Jylhä-Ollila, M., Laine-Kaulio, H., Niinikoski-Fuβwinkel, P., Leveinen, J., Koivusalo, H. 2020. Water Quality and Organic Matter Removal in Natural Bank Infiltration at a Boreal Lake in Finland. Hydrogeology Journal, in print.

How to cite: Jylhä-Ollila, M., Laine-Kaulio, H., Niinikoski-Fuβwinkel, P., Leveinen, J., and Koivusalo, H.: Groundwater quality development in response to infiltration of lake water into an aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8771, https://doi.org/10.5194/egusphere-egu2020-8771, 2020.

In the Israeli water supply system there is a continuous development of new water sources to meet the demand. Managed aquifer recharge is operated over the years to recharge the older in use, exploited aquifer by the newly developed sources. The Mediterranean coastal aquifer in Israel and drilling technology that matured in the beginning of the 20 century enabled the fast development of cities, towns and villages along this coastline. Naturally, this lead to over exploitation of this aquifer that peaked in the 1950s. New water resources were developed since, and surpluses beyond direct supply, from these sources were/are used to recharge the coastal aquifer. These new water sources (years used also for managed recharge) include: Ephemeral streams flood-water (1959-present); the neighbour, mountain aquifer (1950s-1990s); Sea of Galilee lake water (1960s-1990s); wastewater effluents (1987–present); and desalinated seawater (2014-present). Manged recharge from these sources through wells and infiltration ponds on the sandy soils overlying this aquifer will be discussed from the following viewpoints: hydrogeology and land-use, injection-well design, variability of availability and water quality and usage.

How to cite: Kurtzman, D. and Guttman, J.: Filling the “old” aquifer with water from new sources: A perspective on Managed Aquifer Recharge in Israel, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13605, https://doi.org/10.5194/egusphere-egu2020-13605, 2020.

The Lower Yarmouk Gorge (LYG) marks both hydrogeological and Geopolitical triple junction. It serves as a meeting point for groundwater flowing from the Syrian Haurn Plateau, the Jordanian Ajloun Mountain and the Israeli Golan Heights. It is also the natural outlet of the 6,833 km² transboundary Yarmouk drainage basin, which was one of the main tributaries of the Jordan River. Within the gorge, springs and boreholes exhibits various water types flowing in a wide range of temperatures. For the three riparian states, the uncertainty of groundwater origin and flow paths imposes difficulties on the management of water flowing towards the Gorge. In last few years a series of studies have attempted to unveil some of the mystery. Numerical representation of rainfall field is a method developed in order to cope with the lack of data and contributed to the assessment of water consumption and aquifer discharge at the ungauged/unreported upstream parts of the basin (Shentsis et al., 2018 and 2019). Hydrochemistry of groundwater has been investigated in light of the natural processes in the larger Yarmouk Basin and a methodology was devalued for identifying different groundwater bodies in multi-aquifer systems (Möller et al., 2016; Rosenthal et al., 2020). Finally, a new structural model for the transboundary Lower Yarmouk Gorge has been suggested based on data from Israel and Jordan (Inbar et al., 2019) and several numerical simulations have been conducted for the study of this enigmatic fractured hydrothermal system (Magri et al., 2015 and 2016; Gurezki et al., 2016). Finally, it seems that currently we are a few steps closer towards a better understanding of this complex transboundary system and the lessons learned here can be used in other transboundary system around the world.

Inbar, N., E. Rosenthal, F. Magri, M. Alraggad, P. Möller, A. Flexer, J. Guttman, and C. Siebert (2019), Faulting patterns in the Lower Yarmouk Gorge potentially influence groundwater flow paths

Magri, F., N. Inbar, C. Siebert, E. Rosenthal, J. Guttman, and P. Möller (2015), Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin

Magri, F., S. Möller, N. Inbar, P. Möller, M. Raggad, T. Rödiger, E. Rosenthal, and C. Siebert (2016), 2D and 3D coexisting modes of thermal convection in fractured hydrothermal systems - Implications for transboundary flow in the Lower Yarmouk Gorge

Möller, P., E. Rosenthal, N. Inbar, and F. Magri (2016), Hydrochemical considerations for identifying water from basaltic aquifers: The Israeli experience

Rosenthal, E., P. Möller, I. Shentsis, C. Siebert, F. Magri, J. Guttman, and N. Inbar (2020), Natural Processes determining the hydrochemistry of the groundwater in the Yarmouk basin

Shentsis, I., N. Inbar, E. Rosenthal, and F. Magri (2018), Numerical representation of rainfall field in basins of the Upper Jordan River and of the Yarmouk River

Shentsis, I., N. Inbar, E. Rosenthal, and F. Magri (2019), Assessing water consumption and aquifer discharge through springs based on the joint use of rain and flow data in the Yarmouk River Basin

How to cite: Inbar‬‏, ‪., siebert, C., Guttman, J., Möller, P., Rosenthal, E., Shentsis, I., Raggad, M., Salameh, E., and Magri, F.: The hydrogeology of the transboundary Yarmouk Gorge: a case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17821, https://doi.org/10.5194/egusphere-egu2020-17821, 2020.

Carbonate aquifers supply freshwater to about one-quarter of the world population. Their particular hydrodynamic behavior is a valuable property for groundwater extraction, on the downside, carbonate aquifers are vulnerable to overexploitation and pollution. Fractures, fissures, and typical karst features, such as  conduits and vertical shafts, create high regional hydraulic conductivities and fast response times to hydrological events, complicating numerical modeling and management of carbonate aquifers in general. Here, we develop a new method to assess the vulnerability of Mediterranean karst aquifers concerning shifts in climate. Particularly, we are interested in 1) which types of karst aquifers are most vulnerable and 2) which factors have the highest impact on their climate vulnerability.

Our approach is based on a vulnerability index, which is calculated from selected indicators of aquifer behavior that refer to land cover, soil types, wetlands, water demand, current change of groundwater levels, total water volume, run-off, water exploitation index, and freshwater production. First, we calculate vulnerability indices for all karst aquifers – as identified in the World Karst Aquifer Map by the World-wide Hydrogeological Mapping and Assessment Programme (WHYMAP WOKAM v1 database; Chen et al., 2017) – that have at least 90% of their area belonging to Mediterranean climate zones (Csa, Csb, and Csc). Then, we group these aquifers into classes representing different physical behaviors and morphological characteristics (e.g. highly karstified systems in mountainous areas).

An evident approach to investigate various aquifers in terms of their vulnerability is the development of numerical flow models. The advantage is that the boundary conditions, such as average annual precipitation and temperature, can be modified to consider different climatic scenarios. Thus, the resulting impact on water volumes and the aquifer response can be simulated accordingly. However, this approach requires large amounts of data and high computational costs.

Our method uses selected sets of karst aquifers representing different variations of Mediterranean climates (i.e. that are similar in terms of temperature and precipitation patterns). These aquifers are compared by analyzing and plotting regional climate variables versus previously calculated vulnerability indices. By identifying and comparing climate-vulnerability relations within aquifer sets, we can mimic changes in climate for individual aquifers in line with the RCP4.5 scenario until 2050. This approach, which relies on present-day observed conditions, allows us to predict the effect of a changing climate on the vulnerability of an aquifer class without the need to develop a complex numerical model.

The results are visualized in the form of vulnerability maps and used to derive recommendations for the sustainable management of karst aquifers under Mediterranean climates.

How to cite: Nußbaum, P., Somogyvári, M., Bresinsky, L., Löw, J., Schönbrodt-Stitt, S., Sauter, M., Conrad, C., and Engelhardt, I.: Vulnerability assessment of karst aquifers under Mediterranean climates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5112, https://doi.org/10.5194/egusphere-egu2020-5112, 2020.

Karstified aquifers respond rapidly to hydrological events, such as heavy rain storms or draughts. Our ability to predict the response of the aquifer after such events strongly depends on i) temporal and spatial resolution of the available monitoring data and ii) suitable modelling approaches to assess recharge at the respective level of detail. The study catchment, the Western Aquifer Basin (WAB), is Israel´s most important source for freshwater supply. The recharge area of the WAB has an area of 1,812 km². Recharge is characterized by high spatial variability in topography and a high variability in precipitation and temperature, land use, and vegetation. Precipitation also shows a seasonal variability: while annual precipitation mainly occurs during the winter months accompanied by floods in the otherwise dry wadis (October to March, ca. 90 %), summer periods (April to September) are hot and dry, and precipitation decreases to nearly zero.

We employ SWAT to simulate the large-scale hydrological water balance (evapotranspiration, recharge, run-off) in the recharge area of the WAB on a daily and monthly temporal resolution. The SWAT model uses a SRTM DEM from NASA, soil maps from FAO, soil properties of the Harmonized World Soil Database, and land use maps from the ESA CCI project covering the time period from 1992 to 2015. These datasets are merged in SWAT into 361 Hydrologic Response Units with unique characteristics in soil, land use, and slope, respectively. The calibration of soil water balance model with SWAT-CUP employs monthly actual evapotranspiration and daily surface runoff data. Run-off was measured in hydrometric stations between 2004 – 2015. Evapotranspiration with a spatial resolution of 500 m x 500 m is obtained from the MODIS satellite mission and covers a period between 2001 and 2013 with individual time steps of 8 days. Calculated long-term groundwater recharge is compared with spring discharge measured during the period 1990 – 2013. Climate projections have been obtained with the RCM COSMO-CLM at resolution of 8km, under the IPCC RCP4.5 scenario, nested into the MENA-CORDEX domain.

The calibrated water balance model allows for scenario analysis for predicted shifts in climate until 2050 to address the impact of climate change on groundwater recharge. In addition to an increase in temperature, fewer but more extreme rainfall events are to be expected. Furthermore, the effect of future land use changes, such as expansion of farm land or urban areas, on recharge depth are analyzed. Finally, simulated high-resolution recharge provides an updated estimate for the currently developed groundwater flow model of the aquifer system. SWAT provides daily recharge for the equivalent porous medium model of the WAB, simulated by MODFLOW. One of our challenges is the calculation of recharge in the hilly region i) characterized by steep slopes and ii) vadose zones of several 100 meters of thickness. Our investigations are expected to provide information on the impact of shifts in climate and global changes on recharge processes and to illustrate the effect of short-term hydrologic events on water resources in large carbonate aquifers under Mediterranean climate.

How to cite: Hepach, P., Nooruddin, J., Bucchignani, E., Sauter, M., and Engelhardt, I.: Estimation of temporally high-resolution recharge in a Mediterranean large karst aquifer system considering climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5223, https://doi.org/10.5194/egusphere-egu2020-5223, 2020.

Groundwater recharge is an important variable for sustainable groundwater resources management in regions affected by water scarcity. The specifics of the Mediterranean require adapted techniques to also account for climate change implying a higher frequency of extreme events. Appropriate techniques are highly relevant for recharge with low rates. We compare three methods for the Western Mountain Aquifer, a karst in Israel: soil moisture budget calculations at basin scale, empirical functions, and machine learning algorithms. Resulting recharge are compared with measured spring discharge.

Neural networks have the advantage of not requiring much knowledge about physical processes or hydrogeological and hydrological conditions, nor about model parameters. This data-driven machine learning algorithms learn the non-linear relationship between precipitation events and spring water discharge given a sufficient amount of training data is available. After training, the neural network could be used as a nonlinear function to model recharge of any predicted precipitation time series. However, this approach does not allow for any quantitative analysis of external forcing, such as land use, or internal parameter, such as soil characteristics, nor does it account for any expected future change in precipitation pattern.

Hydro-pedotransfer functions (HPTF) are based on empirical relationships between precipitation and recharge. HPTFs account for potential evapotranspiration, annual precipitation, land cover, and a critical water supply (a threshold when actual evapotranspiration depends only on atmospheric conditions). Resulting percolation rates consider i) vegetation types, ii) precipitation during the vegetation growth period, iii) runoff, iv) plant available soil water, and v) capillary rise. The application of HPTF to a karst aquifer has the advantage that only limited input data are required. However, our results indicate that HPTFs are not able to capture the rapid recharge component observed in karst systems and thus underestimate recharge.

The Soil Water Assessment Tool (SWAT) employs a hydrological and soil moisture budget calculations. Objective functions are actual evapotranspiration and surface runoff. Evapotranspiration is obtained from MODIS remote sensing data. Calibration of actual evapotranspiration is especially challenging for summer periods due to the impact of vegetation and irrigation. However, the most relevant parameter determining daily recharge rates are water loss by surface-runoff and surface water storage in wadi beds generating episodic recharge.

Impact of shifts in climate is considered by climate projections obtained with the RCM COSMO-CLM at resolution of 3 km, under the IPCC RCP4.5 scenario, nested into the MENA-CORDEX domain. However, we believe that changes in land use from natural vegetation (trees, grass-, and shrublands) to rain-fed agricultural area could possibly shift the water budget from deficit to surplus conditions (recharge dominated). During the period 1992 to 2015 natural vegetation decreased by 8% and urban areas increased by up to 6%, while (rain-fed) agricultural areas remained almost constant. We investigate if land use changes might have (a much) larger impact on percolation rates than the predicted climate change effect. Thus, in future recharge may be controlled and enhanced in regions with water scarcity by better management of land use employing an optimized combination between precipitation, irrigation, and crop type.

How to cite: Engelhardt, I., Banusch, S., Hepach, P., Somogyvári, M., Wessolek, G., Truong, T.-M., Bucchignani, E., Conrad, C., Livshitz, Y., and Sauter, M.: Identification of an appropriate method for assessing large-scale and long-term recharge in Mediterranean karst aquifers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2021, https://doi.org/10.5194/egusphere-egu2020-2021, 2020.

Integrated surface-subsurface flow models solving the Richards’ equation allow to simulate flow within all compartments (e.g. vadose, phreatic and surface zone) and their reciprocal interaction, and provide a useful tool to investigate the impact of climatic changes on infiltration dynamics. The Mediterranean karst aquifers are in particular prone to shifting climates, as a decrease in mean precipitation with increasing intensity and frequency of short-duration extreme rainfall, may have a significant impact on recharge dynamics and the overall water budget. Here, we use the finite element, distributed, multi-continuum flow simulator HydroGeoSphere (Aquanty, 2015) on a high-performance-computing platform to simulate infiltration and groundwater flow of the Western-Mountain-Aquifer (WMA) considering changing hydrologic conditions. A thin soil cover and abundant exposed bare karstic carbonate rock compose the recharge area, providing efficient pathways for fast direct infiltration along karst features (e.g., sinkholes and dolines). The lowered total annual precipitation may not result in a decrease in recharge since the severity and frequency of individual rainfall storms are projected to increase.

To account for the duality of karst flow dynamics, both in the vadose and phreatic zones, with rapid flow through conduits and slow flow through the fractured rock matrix, we apply a double-continuum approach based on the volume-effective Richards’ equation with van Genuchten parameters. A 2-D friction-based overland flow continuum, coupled via a first-order exchange term to the subsurface, accounts for overland flow due to infiltration excess. This allows to represent the partitioning of rainfall into diffuse and rapid direct recharge, e.g., along dry valleys or sinkholes. This modeling approach, therefore, accounts for complex spatially distributed infiltration characteristics of the rock-soil landscape, with focused recharge along karst features and transmission losses of ephemeral streams (wadis) under variable precipitation patterns.

To get a better understanding of the complex interaction dynamics of the surface and subsurface domain in a coupled unsaturated single- and dual-continuum model we carried out small-scale process-oriented studies. Two types of synthetic karst features, (1) a dry valley averaged from field data (i.e., Wadi Natuf) and (2) an analytical generalized doline, were investigated. Geometries close to natural systems, such as sub-catchments of the WMA, were implemented. Sensitivity studies reveal complex dependencies of domain properties on linear- and log-scales. However, the exchange parameters controlling the coupling between the subsurface continua are insensitive.

How to cite: Bresinsky, L., Kordilla, J., Thoenes, E., Würsch, T., Engelhardt, I., and Sauter, M.: Simulating Climate Change Impacts on the Recharge Dynamics of a Mediterranean Karst Aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17009, https://doi.org/10.5194/egusphere-egu2020-17009, 2020.

The interrelation between ground water and surface water has a serious consequence on water management. Groundwater level depletion gradually occurs in high water stress areas when there is groundwater extraction. Here we study the spatial and temporal patterns of surface water and groundwater flow in the Sabarmati Basin. We analyze the effect of groundwater pumping for irrigation purposes on the depletion of groundwater. We also assess the influence of drought and flooding on groundwater recharge in the basin, by modelling the basin in SWAT-MODFLOW for a period of 1901 to 2019. Our results show that the groundwater recharge in Sabarmati basin, which is a part of semi-arid region of India, is significantly affected by hydrological extremes (floods and droughts) during the monsoon (June – September). The insights of our research will help to overcome the grand challenge of water management in a changing climate scenario.

How to cite: Sinan, M. and Mishra, V.: Application of SWAT-MODFLOW Model to Understand How Groundwater Recharge in Sabarmati River Basin is Affected by Extreme Climate Events. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21197, https://doi.org/10.5194/egusphere-egu2020-21197, 2020.

By use of transient and distributed groundwater-surface water flow models, simulated time series of stream discharge and groundwater level for monitoring networks, groundwater bodies and river reaches have been analysed for a historical period and four different future scenarios toward 2100 in two large-scale catchments in Denmark. The purpose of the climate scenarios has been to qualify the existing knowledge on how future climate change most likely will impact hydrology, groundwater status and Ecological Quality Elements (EQR- Ecological flow in rivers). Another purpose has been to identify whether foreseen climate changes will be detected by the surface water and groundwater monitoring networks, and to which degree the River Basin Management Plan measures for supporting the goal of good quantitative status are robust to the projected changes in water balance and ecological flow. The developed hydrological models were run with climate inputs based on selected RCP4.5 and RCP8.5 climate model runs (RCP8.5 wet, median, dry and RCP4.5 median). Changes in groundwater quantitative status and ecological flow metrics were calculated based on 30-year model runs driven by RCP8.5 for 2071-2100 (RCP4.5 for 2041-70) and compared to 1981-2010.

Overall the four scenarios results in very significant water balance changes with increased precipitation: 3% to 27%, evapotranspiration: 6% to 17%, groundwater recharge: 0% to 49%, drainage flow: 0% to 71%, baseflow: 0% to 31% and overland flow: 16% to 281%. For one catchment an increase in abstraction of 23% to 171% due to an increase in irrigation demand by 36% to 113% is foreseen. The results have wide implications for groundwater flooding risks, quantitative status and ecological flow metrics. Most sensitive is changes in ecological flow conditions in rivers for fish, showing a relative high probability for decreased state for 10-20% of the reaches for the RCP8.5 wet and dry scenarios due to more extreme hydrological regimes toward 2071-2100. Maximum monthly runoff is increased for winter months by 100% for RCP8.5 wet and median scenarios and around 10% for RCP8.5 dry scenario. Annual maximum daily flows is simulated to increase by up to a factor of five, and late summer low flows decreased.

Impacts on groundwater levels and water balances of groundwater bodies will be significant, with increased seasonal fluctuations and also increased maximum and decreased minimum groundwater levels for 30 year periods for 2071-2100 compared to 1981-2010.

More rain, both when we look back on historical data and when we look forward with latest climate projections will result in more frequent flooding from groundwater and streams in the future. At the same time, the temperature and thus evapotranspiration rises. This means that in the long term we will have increased challenges with drought and increased irrigation demands on sandy soils while evapotranspiration will also increase on the clayey soils. This will result in greater fluctuation in the flow and groundwater levels between winters and summers, and between wet and dry years, challenging sustainable groundwater abstraction and maintaining good quantitative status of groundwater bodies.

How to cite: Jakosben, A., Henriksen, H. J., Pasten-Zapata, E., Sonnenborg, T., and Troldborg, L.: Evaluating the effects of climate change for groundwater quantitative status in Denmark, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19101, https://doi.org/10.5194/egusphere-egu2020-19101, 2020.

This study aims to use an integration of genetic algorithm (GA) model and particle swarm optimization (PSO) with the Deep Learning Neural Networks (DLNN) for groundwater contamination vulnerability. Miryang, a city in the northeastern portion of Gyeongnam Province, South Korea was selected as a case study since it showed urban and rural functions and had undergone groundwater pollution. To initialize the modeling purposes, parameters such as depth to water, net recharge, topographic slope, aquifer type, impact to vadose zone, hydraulic conductivity and land use were classified into numerical classes and used as input variables. Two-hybrid models of DLNN-GA and DLNN-PSO were implemented using 95 measured nitrate concentration from monitoring wells for the training and testing of artificial neural networks. The performance of the hybrid models was evaluated by several statistical criteria of error: Mean Square Error (MSE), Root Mean Square Error (RMSE) and Mean Average Error (MAE). The hybrid vulnerability models were also validated by the Area Under the curve (AUC). DLNN-PSO showed the highest (AUC=0.974) performance in comparison with DLNN-GA (AUC=0.954) and Shallow Artificial Neural Networks model (AUC=0.70). The results showed that the proposed hybrid models were more superior than the benchmarked shallow artificial neural networks model used for groundwater contamination vulnerability mapping as a good alternative several years ago.

How to cite: Elzain, H. E., Chung, S. Y., Senapathi, V., and Park, K.-H.: Deep Learning Neural Networks with Metaheuristic Optimization Algorithms for Groundwater Contamination Vulnerability Mapping in Miryang Aquifer, South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7377, https://doi.org/10.5194/egusphere-egu2020-7377, 2020.

Groundwater is a vital source of freshwater, an estimated 39% of all freshwater withdrawals in India are from groundwater. However, groundwater is a finite resource, and there is evidence that aquifers in Peninsular India are being depleted faster than they can recharge. This imbalance is likely to get worse in the future with the effects of a changing climate and increasing population.

It is clear that an accurate assessment of groundwater availability, now and in the future, is essential, but this is a challenge. High spatial variability coupled with the difficulty in measuring aquifer properties make it difficult to model groundwater at a basin scale. To address this, the representation of groundwater within the Global Water AVailability Assessment (GWAVA) model has been developed to provide greater insight into groundwater resources as part of an integrated water availability assessment in the Cauvery basin (81,000 km²) in Peninsula India.

For this assessment, the GWAVA model was adapted to include an improved groundwater representation, along with the effect of small-scale human interventions intended to artificially recharge groundwater. The model was calibrated against streamflow and groundwater levels across the basin. Model runs were executed for a baseline period and for future decades, using relevant combinations of CMIP5 climate (RCP) and shared socio-economic pathways (SSP) scenarios.

Over the baseline period (1986-2005), groundwater abstraction exceeded net aquifer recharge over 66% of the area of the basin. In the future (2061-2080), this was predicted to increase to 71% under the “worst-case” scenario (RCP 8.5, SSP 3) and 93% under the “best-case” scenario (RCP 4.5, SSP 1). This supports the existing evidence that groundwater resources are currently overexploited in the Cauvery basin and suggests that this situation will get worse in the future.

An additional output of this study has been to identify gaps in the data necessary for groundwater modelling (e.g. characteristics of aquifers, density of interventions, time series of aquifer levels and groundwater pumping), in terms of data availability and confidence. This knowledge can be used to inform future data collection to maximise the usefulness of future observations.

This method can be applied to other regions with a high dependency on groundwater, such as sub-Saharan Africa, for integrate water-resource assessments. It could also be extended in the future to include a water-quality component in the groundwater processes.

How to cite: Baron, H., Keller, V., Horan, R., Houghton-Carr, H., Rees, G., Collins, S., Jackson, C., Mujumdar, P., Muddu, S., and Rajendran, R.: Estimating current and future groundwater resources across the Cauvery basin using a macro-scale gridded water-resource model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9719, https://doi.org/10.5194/egusphere-egu2020-9719, 2020.

Due to the scarcity of available surface water, many irrigated areas in North China Plain (NCP) heavily rely on groundwater, which has resulted in groundwater overexploitation and massive environmental impacts, such as groundwater depression core and land subsidence. The net groundwater depletion, one of the groundwater indicators, means the actual groundwater consumption for human impact. This indicator is quite essential for the evaluation of the effects of agricultural activities in well irrigation areas. However, net depletion forecasts, which can help inform the management of well irrigation areas, are generally unavailable with easy methods. Therefore, this study explored machine learning models, Long Short-term Memory (LSTM) networks, to forecast net groundwater depletion in well irrigation counties, Hebei Province. Firstly, Luancheng county was selected to construct the forecasting model. The training dataset was prepared by collecting the measured precipitation, remote sensing evaporation and groundwater table from 2006-2017. Besides, an agro-hydrological model (Soil-Water-Atmosphere-Plant, SWAP) with an optimization tool (Parameter ESTimation, PEST) was used to calculate the net depletion, and an unsaturated-saturated zone water balance conceptual hydrological model was constructed to calculate the net groundwater use. Secondly, to determine the effect of training data type on model accuracy, freshwater budget (evaporation minus precipitation), change of groundwater table and net groundwater use were chosen as training inputs by analyzing related temporal variable characteristics of net groundwater depletion. The response time of training inputs with net groundwater depletion were also approximated with highest cross-correlation value (CCF). Then, by circular bootstrapping methods to enlarge the Luancheng datasets from 2006-2016, the annual and monthly model for forecasting the net depletion were respectively trained with enlarged Luancheng datasets. Additionally, to test the model’s ability to predict the net groundwater depletion in other well irrigation areas with the similar rule of groundwater depletion, the annual and monthly forecasting scenarios were also carried out in the adjacent county, Zhaoxian. The results showed that both of the monthly and annual models estimating the groundwater net depletion had good performance in Zhaoxian from 2006-2017, with NSE of 0.91 and 0.81, respectively. According to the modelling results, further analysis showed that groundwater depletion in research counties mainly occurred in spring (March to May) and winter (December to February). In addition, the major factor leading to groundwater depletion in spring and winter was freshwater budget; while in summer and autumn, soil moisture determined the depletion activity. These results demonstrate the feasible use of LSTM networks to create annual and monthly forecasts of net groundwater depletion in well irrigation areas with similar depletion rule, which can provide valuable suggestion to well irrigation management in NCP within a challenging environment.

Keywords: net groundwater depletion; long short-term memory; well irrigation areas

How to cite: Yuheng, L. and Lihua, T.: Forecasting Net Groundwater Depletion in Well Irrigation Areas with Long Short-term Memory Networks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12250, https://doi.org/10.5194/egusphere-egu2020-12250, 2020.

Groundwater is said to be depleting at an alarming rate, and is stated as a major concern for agriculturally driven countries like India. Therefore, understanding the dynamics of water system of the country is prerequisite for assuring its sustainability. According to the GRACE (Gravity Recovery and Climate Experiment) satellite data, the declining TWS (terrestrial water storage) trends are apparent in north and south of India during 2003-2016, while the Narmada river basin which is situated in the central west of the country, shows apparent increase of TWS. In this study, part of the Narmada river basin was chosen as the study site. The major occupation in the basin is agriculture, and hence, water is, in principle, consumed for irrigation. Between 2003 and 2016, the two dams (Indira Sagar dam (2005) and Omkareshwar dam (2008)) were constructed, and the resulting canal system was considered to highly influence water resources availability in the area. To understand the possible effects of the canal system on groundwater level behaviour, we chose the Maheshwar block as the study domain because of its simple canal system layout and single basaltic aquifer setting. The groundwater levels were analysed based on two situations, i.e., before and after canal construction. For the analysis, two distinct seasons, i.e., dry pre-monsoon and rainy monsoon seasons were also taken into account. In the block, the first canal was constructed by 2010, and second by 2013. Based on the extent of each Canal Command Area (CCA), the block was divided into two zones, Zone A (CCA under 1^st canal) and Zone B (CCA under 2^nd canal). Among the wells studied, five were located within Zone A. After the canal construction, on an average, about 2 m rise was observed in these well water levels, that is, about 2.45 m in pre-monsoon while 1.62 m in monsoon seasons, respectively. Similar analysis was performed for wells not located in CCA, and it was found that no recognizable change of the groundwater levels was observed. The changes in the land use land cover (LULC) pattern were studied using Landsat 5, Landsat 7 ETM+ and Landsat 8 OLI/TIRS imageries in the block. All the LULC maps were cross-checked with maps from National Remote Sensing Centre (NRSC), India, and these were consistent between each other. The expansion of the agricultural area was studied through 2003-2016. The cultivated area increased from about 8% before the operation of the canal to about 27% after operation in Zone A, whereas the increase was smaller in Zone B, that is, from 2% to around 11%. Based on the NDVI (Normalized Difference Vegetation Index) obtained through Landsat images from different seasons, we also observed that cropping patterns have changed from fallow/single cropping to double/triple cropping after the introduction of canal system in both zones. Based on observations, available amount of water and groundwater storage have increased after canal operation compared with before the operation, and this may at least partly explain the reason why TWS has increased in this area.

How to cite: Shiradhonkar, S. and Tokunaga, T.: Changes of groundwater levels and land use with the introduction of canal system in Maheshwar block of Narmada basin (Central India), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17577, https://doi.org/10.5194/egusphere-egu2020-17577, 2020.

Dramatic population growth and climate change lead to an increasing demand for groundwater resources. According to The 2018 edition of the United Nations World Water Development Report, nearly 6 billion people will face severe water scarcity by 2050. Groundwater represents the world’s largest available freshwater resource and it is essential for domestic purpose, industrial, and agricultural uses. Therefore, it is very important to identify the potential locations for new groundwater zones development. Here, we utilized geographic information system (GIS) and remote sensing (RS) techniques for the delineation of groundwater potential zones in the Titel Municipality, located in the Autonomous Province of Vojvodina. The groundwater in the study area is affected by elevation difference, agricultural production, and its geographical position. Titel Municipality has a very good agriculture potential that can be only fully exploited by improving groundwater management. Considering that, for the delineation of groundwater potential zones we prepared 6 thematic layers such as geology, geomorphology, land use/land cover, soil, drainage density, and slope. According to their relevant importance in groundwater occurrence, all layers and their features were assigned weights using the Saaty’s scale. Weights of layers were normalized using analytical hierarchical process techniques (AHP). Finally, layers were integrated and overlaid using QGIS software for generating the Groundwater Potential Zone (GWPZ) map of the study area. As a result, the groundwater potential zones in the Titel Municipality were characterized and classified into five classes as very good (7.13%), good (35.44%), moderate (21.27%), poor (31.41%) and very poor (3.11%). With these techniques, we showed that very good and good groundwater zones are predominantly located in the alluvial plain and the lower river terrace, while poor zones mostly evident on the landform of the loess plateau and artificial surface. The GWPZ map will serve as a useful guide for sustainable management and utilization of the region as well as to improve the irrigation facility and develop the agriculture productivity of the area.

How to cite: Radulović, M., Đorđević, T., Grujić, N., Pejak, B., Brdar, S., Savić, S., and Pavić, D.: Using GIS and Remote Sensing Techniques for Delineation of Groundwater Potential Zones - A Case Study of the Titel Municipality, Serbia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22150, https://doi.org/10.5194/egusphere-egu2020-22150, 2020.

Groundwater is a limited resource in coastal hydrogeological systems, especially in semi-arid environments where the irrigation demands are very high. Management of such hydrosystems is a very challenging process; while water conflict between different users as well as climate change conditions are magnifying this problem.

Managed aquifer recharge – storing water in aquifers during times of excess – is considered as a sound engineering technique and a key strategy to support groundwater resources in such hydrologically sensitive regions by providing intermediate storage, bridging the gap between water demand and availability. In addition to the above, innovative modelling techniques that apply participatory approaches can be proved a valuable supporting tool for the management of groundwater resources within an optimized manner.

The coastal field of Argolis (S. Greece) is used as a reference site to illustrate the above, where Managed Aquifer Recharge is applied on a full-scale mode since 1990, using karst groundwater as a recharge water source. The study area involves an extended and complex water infrastructure systems that includes: (a) a main intake structure -a submarine dam exploiting a system of submarine karstic springs-; (b) a conveyance system -mainly open canal structures- that assures the transport of water from the main intake structure and main pumping station up to the agricultural area; and (c) a cluster of Managed Aquifer Recharge facilities that divert water towards the subsurface either through deep groundwater wells or infiltration ponds at selected parts of the aquifer.     

This research presents the results of hydro‐environmental modelling activities of Managed Aquifer Recharge and the preliminary work on participatory driven water resources modelling scenarios. This study is envisaged to contribute in the identification and valuation of socio‐economic and environmental processes and linkages of groundwater uses and services.

How to cite: Kallioras, A., Chrysanthopoulos, E., Mitropapas, A., Floros, E., Nalbadi, S., Seferou, P., Pouliaris, C., and Markantonis, K.: Water resources management of coastal semi-arid environments using Managed Aquifer Recharge and participatory modelling approaches. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21536, https://doi.org/10.5194/egusphere-egu2020-21536, 2020.

Earthquake of magnitude M5.4 the second largest recorded earthquake occurred in Pohang, South Korea at 05:29:32 (UTC time) on November 15, 2017. The M5.4 event and hundreds of aftershocks produced extreme impacts across the area to date along with human and property damages. The distance between the epicenter of the M5.4 Pohang earthquake and the groundwater observation well is about 43 km for KJ-well and about 76 km for YS-well. Records from these two monitoring wells showed groundwater level changes occurred in 2017-11-15 05:30 (UTC time), about 30 seconds after the earthquake. In KJ-well, 8.0 cm of groundwater level change was observed, and in YS-well, about 30.0 cm of groundwater level change. The changes in groundwater level appeared to be a spike-like pattern that rises immediately due to the compressive action of the aquifer as the seismic waves pass through and then return to its original state. Interestingly, the groundwater level changes in YS-well was observed to be approximately three times greater than KJ-well although YS-well is approximately twice as far from the epicenter as KJ-well. The factors causing these different changes were compared and analyzed for the geometry, hydraulic properties, and geological characteristics of the well locations

How to cite: Lee, S.-H., Lee, J. M., Yoon, H., and Kim, Y.: Different responses of groundwater level changes through hydrogeological characteristics due to M5.4 Pohang earthquake, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12629, https://doi.org/10.5194/egusphere-egu2020-12629, 2020.

Chesapeake County Groundwater Problem

Kenneth C. Newsome Freedom High School Prince William County Virginia

Teaching students the impact of groundwater pollution and its effect on humans

This activity was modified from an activity from the Math Science Center in Richmond, Virginia.  Students construct models using six paper models of a hypothetical situation where a farmer and lighthouse keeper are having well water issues. The students are acting as a hydrogeologist and are consulting the farmer and lighthouse keeper.  This scenario is being played out on the banks of the Chesapeake Bay in Virginia.  The farmer is having trouble with his house well running dry, while his well at his barn is always supplying water.  The lighthouse keeper and his wife are wondering why their water is undrinkable, and their house plants are dying.  The lighthouse keeper claims the farmer is responsible for the undrinkable water.  The outcome is the farmer's house well is dug too shallow, while his barn well is also close to a manure pile and livestock yard.  The lighthouse keeper's well is too close to the saltwater of the Chesapeake Bay, and the intrusion of salt is making the water undrinkable.  This activity has students problem-solving water pollution issues, and this activity has them figure out the root cause of water pollution.  Students are then asked to apply this knowledge to a newly discovered planet with the same water pollution issues.       

How to cite: Newsome, K.: Chesapeake County Groundwater Problem Hands on Simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7869, https://doi.org/10.5194/egusphere-egu2020-7869, 2020.

Approximately 500 million Europeans use a groundwater source for water consumption on a daily basis. Private (unregulated) groundwater wells are key sources of domestic drinking water in the Republic of Ireland (ROI) with approximately 750,000 users. The distribution of groundwater wells in the ROI is highly concentrated in rural areas in correspondence with the absence of piped infrastructure. The nexus of key (extra-)local factors, including high private groundwater reliance, ubiquity of domestic wastewater treatment systems and pastoral agriculture in rural areas, in conjunction with a temperate maritime climate and distinctive hydro(geo)logical settings, has been linked to a high groundwater susceptibility to contamination and risk of waterborne enteric infection.

DESIGN focuses on the incidence and sources of verotoxigenic-producing Escherichia coli (VTEC) and Cryptosporidium spp. – the most prevalent waterborne pathogens inducing enteric illness in the ROI – associated with private groundwater wells. The findings of a systematic literature review focusing on the prevalence of Cryptosporidium in domestic groundwater supplies are presented. Calculated detection rates for groundwater wells (19%) and samples (13%) indicate Cryptosporidium spp. contamination of domestic groundwater supplies is common, representing a latent health risk of direct concern to groundwater consumers and public health authorities. Presented figures provide unprecedented “baselines” highly applicable in groundwater/catchment management and epidemiology (e.g., QMRA). Several knowledge gaps were identified with the lack of standardized reporting among investigations emerging as a key concern.

The results of temporal (i.e., repeat) sampling regimes analysing the spatio-temporal incidence of Cryptosporidium and VTEC in groundwater wells are also presented. Sampling locations (n = 80) were geo-referenced and linked to multiple variables (e.g., land-use, agricultural statistics, hydrogeology) compiled in a novel geo-database. In conjunction with supply infrastructural data, relevant risk factors associated with VTEC and Cryptosporidium well contamination were identified. Furthermore, incorporating previously available data from project partners, stochastic QMRA and Environmental Fate Model(s) were produced to assess the relative risk of VTEC well contamination and seasonal influence. The explorative Cryptosporidium sampling regime provides the first national account of (oocyst) incidence in domestic groundwater infrastructure enabling insights into potential environmental sources and (surface-groundwater) transport mechanisms. The results obtained represent a stepping stone towards the development of bespoke groundwater management strategies in the ROI based on the ‘One Health’ concept.

How to cite: Chique, C., Hynds, P., Burke, L., Morris, D., Ryan, M., and O'Dwyer, J.: Detection of Environmental Sources of Infectious Diseases in Groundwater Networks (DESIGN) – Cryptosporidium and VTEC Incidence in the Republic of Ireland., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4941, https://doi.org/10.5194/egusphere-egu2020-4941, 2020.

Groundwater flowing through coastal aquifers is increasingly impacted by human pressures as consequence of a growing demand on drinking water, tourism and agriculture, among others. Thus, groundwater availability very often depend on its quality since water salinization and pollution are the main challenges for water management because of seawater and freshwater interaction. Therefore, it is crucial to monitor the availability of groundwater and its quality under changing scenarios where this water resource can be specially threatened.

This study aims to assess the spatial distribution and time evolution of groundwater levels and hydrochemistry of the alluvial aquifer of the Bajo Guadalhorce Valley (Málaga, S Spain) for the evaluation of its quantitative and qualitative status. To that, groundwater level, electrical conductivity and Cl^- and SO₄^2- concentrations of water have been measured in a field sampling campaign carried out in the alluvial aquifer of the Bajo Guadalhorce Valley (Málaga, S Spain) in April 2017. Additionally, historical data from the last 40 years have been compiled.

Results show that groundwater generally flow towards the Guadalhorce River, where gaining relationship remains more patent in its lower river stretch, and the Mediterranean Sea. Some negative groundwater elevations close to the coastal fringe are observed in several piezometers because of pumping during the study period. Electrical conductivity values were, generally, lower than 4 mS/cm in all samples and the major changes in groundwater mineralization were determined in the Guadalhorce River Mouth. In this aquifer sector, substantial increases in groundwater mineralization were identified, up to 50% in some observation points. Cl^- and SO₄^2-concentrations in groundwater (the more concentrated solutes of all) evolve similarly in time to that of electrical conductivity, with maximum recorded values up to 10000 mg/l and 2000 mg/l, respectively, the coastal area in 2017.

Changes in EC and Cl^- and SO₄^2- concentrations in the river mouth area could be related to the land use changes that took place here between 1997 and 2003, where channelization works resulted in the splitting of the river in two branches. This could have affected to the aquifer hydrodynamics, due to the reduced groundwater discharge to the river mouth area between both branches. This could have favored the mixing among surface water, sea water and groundwater. Also, the urbanized area has increased over the years, reducing the recharge area of this part of the aquifer, but also flowing groundwater has increased because of pumping reduction (up to 7 hm³/year). The presence of Cl^- in the aquifer, as well as SO₄^2-, is due to evaporite dissolution and the interaction with the Mediterranean Sea in the coastal area. An extra input of SO₄^2- comes from of the fertilizers used in agriculture.

The availability of long-term hydrogeological data in a coastal aquifer (1976-2017) has allowed to check a remarkable salinization in the coastal area, caused by land use modifications. So, the monitoring of hydrogeological data is a very important tool to be used by land managers in coastal aquifers, where groundwater can be seriously endangered by human activities.

How to cite: Nieto López, J. M., Barberá Fornell, J. A., and Andreo Navarro, B.: Hydrodynamic and hydrochemical evolution of the Bajo Guadalhorce Valley alluvial aquifer (Málaga, S Spain) in the last 40 years, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22655, https://doi.org/10.5194/egusphere-egu2020-22655, 2020.

Lanyang Plain in northwestern Taiwan is an intensively productive agricultural area, most from the cultivation of crops and aquaculture. Groundwater fi

How to cite: Liang, C.-P., Sun, C.-C., Chen, J.-S., and Xie, Y.-Y.: Application of artificial intelligence method to develop a reliable model for spatially assessing the health risk from arsenic exposure via drinking groundwater, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2836, https://doi.org/10.5194/egusphere-egu2020-2836, 2020.

The Cornia Valley aquifer system (Tuscany, Italy) is the main source for irrigation, industrial purposes, and for potable water supply for the zone and the Elba island. Sixty years of its overexploitation caused a remarkable potentiometric drawdown accompanied with a wide seawater intrusion and a severe degradation of the quality of the groundwater (Rossetto et al., 2018; 2019).

In the early 2000s, extensive research regarding anomalous high concentrations of Boron in the Cornia Valley was carried out. These studied the hydrochemistry of the area, determining also anomalous high concentrations of Arsenic (Pennisi et al., 2009). In addition, one of the biggest schemes treating Arsenic for drinking water started operating with other two plants for Boron (Comune di Suvereto, 2013). Furthermore, in 2015 the LIFE REWAT project was started in order to set a strategy to recover and improve the availability of water in the area through a series of technical and social interventions (Rossetto et al., 2018).

Within LIFE REWAT, Managed Aquifer Recharge (MAR) was identified as a solution to counterbalance the stressed hydrologic system. Thus, a pilot MAR scheme infiltrating harvested rainwater from the Cornia River was implemented. It is provided by a hi-tech high-frequency automated and remotely controlled system for operating the plant and monitoring water quantity and quality. This system is supported by the data gathered from different sensors installed in the area, recording into a database. Additionally, discrete groundwater sampling takes place monthly (Rossetto et al., 2018; 2019).

The database contains recordings from two consecutive hydrological years. The first year measurements and samplings were done under natural recharge conditions, while during the second year the MAR scheme was under operation. This initial data provides insights on concentration variations of Boron and Arsenic after one-year operation of the MAR scheme. However, the main processes involved still need to be understood. Therefore, long-term and short-term dedicated field experiments are designed to analyse the induced variations. This work presents a model based hydrogeochemical approach for the behaviour analysis of these elements under MAR operations to determine the transiency of these concentration changes.

Acknowledgements

This paper is presented within the framework of MARSoluT ITN (www.marsolut-itn.eu), a Marie Skłodowska-Curie Actions (MSCA) Innovative Training Network (ITN) funded by the European Commission (Grant Agreement 814066).

References

Comune di Suvereto (2013). Impianti per Arsenico e Boro in Val di Cornia. http://www.comune.suvereto.li.it/moduli/output_immagine.php?id=709 [Webpage. Italian. Accessed the 14/01/2020]

Pennisi, M., Bianchini, G., Kloppmann, W., & Muti, A. (2009). Chemical and isotopic (B, Sr) composition of alluvial sediments as archive of a past hydrothermal outflow. Chemical Geology, 266(3-4), 114-125.

Rossetto, R., De Filippis, G., Piacentini, S. M., Matani, E., Sabbatini, T., Fabbrizzi, A., ... & Menonna, V. (2018). Using flood water in Managed Aquifer Recharge schemes as a solution for groundwater management in the Cornia valley (Italy). Geophysical Research Abstracts (Vol. 20).

Rossetto, R., De Filippis, G., Piacentini, S. M., Neri, S., Continanza, D., Brilli, M., ... & Lazzaroni, F. (2019). Increasing reliability and safety of Managed Aquifer Recharge schemes for tackling water scarcity. Geophysical Research Abstracts (Vol. 21).

How to cite: Caligaris, E. and Rossetto, R.: Arsenic and Boron Hydrogeochemistry behaviour during Managed Aquifer Recharge Operations., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15774, https://doi.org/10.5194/egusphere-egu2020-15774, 2020.