scholarly journals Innovative Hydrogeophysical Approaches as Aids to Assess Hungarian Groundwater Bodies

2021 ◽  
Vol 11 (5) ◽  
pp. 2099
Author(s):  
Péter Szűcs ◽  
Norbert P. Szabó ◽  
Mohammad Zubair ◽  
Sándor Szalai
Keyword(s):  
Geophysical Methods ◽  
Shallow Groundwater ◽  
Clay Content ◽  
Management Plan ◽  
Statistical Interpretation ◽  
Multivariate Statistical ◽  
Joint Application ◽  
Shallow Groundwater Table ◽  
Horizontal Variations ◽  
Resistivity Log

The Hungarian water management plan has lately identified 185 groundwater bodies based on the concepts given by the European Water Framework Directive. Achieving and maintaining the good quantitative and chemical status of these groundwater bodies is of primary importance. It is demonstrated how innovative hydrogeophysical methods can be applied successfully to assess the Hungarian or other international groundwater bodies. By applying geoelectric methods, horizontal layering or large uniform rock units can be well characterized by Wenner–Schlumberger array, also enabling accurate depth determination of the shallow groundwater table. Horizontal variations in the rock type or its state can be well described by dipole–dipole array or, even better, by the newly developed quasi-null arrays. Their joint application may be very straightforward to investigate different aquifer types by giving high-resolution resistivity images as input for hydrogeological modeling. In the identification of porous formations, multivariate statistical interpretation of wireline logs using cluster analysis allows reliable lithological separation of potential aquifers. Their clay content is estimated by robust factor analysis, while their hydraulic properties are directly derived from the resistivity log. For a more effective interpretation, a combination of surface and borehole geophysical methods can be recommended for meeting challenges in hydrogeology and groundwater management.

scholarly journals Geological and geomorphological conditions of Archar-Orsoya lowland as a factor for the formation of groundwater chemical composition and in risk of its contamination

2021 ◽  
Vol 35 (1) ◽  
pp. 63-70
Author(s):  
Sava Kolev ◽  
Mila Trayanova
Keyword(s):  
Chemical Composition ◽  
Sand Dunes ◽  
Shallow Groundwater ◽  
Groundwater Table ◽  
Danube River ◽  
Shallow Water Table ◽  
The Danube River ◽  
Sandy Layer ◽  
Shallow Groundwater Table ◽  
Landslide Slope

The Archar-Orsoya lowland is situated in the Danube floodplain west of the town of Lom, NW Bulgaria. It is aligned in a west-east direction along the Danube River and to the south it is bounded by a high landslide slope, built of Pliocene clays and sands. Parallel to the shore, sand dunes are formed with lowered sections between them, in which there are conditions for swamping. The lowland is made up of the alluvial sediments of the Danube, represented by a lower gravelly-sandy layer and an upper sandy-clayey layer. In the gravelly-sandy layer unconfined groundwater is accumulated, with shallow water table – from 0.5 to 7 m beneath the surface. Groundwater is recharged by infiltration of precipitation, surface water and groundwater, which laterally flows into the alluvium from adjacent aquifers. At high waters, the Danube River suppresses the formed groundwater flow and temporarily feeds it. Due to the described formation conditions in the lowland, the chemical composition of groundwater is formed under the influence of intense dynamics and has a low TDS (total dissolved solids). The shallow groundwater table and the corresponding thin unsaturated zone are a prerequisite for easy groundwater contamination with components entering from the surface. Therefore, a map of depth to groundwater table is drawn to identify the most vulnerable areas.

Using machine learning to downscale simulations of climate change induced changes to the shallow groundwater table

2021 ◽  
Author(s):  
Raphael Schneider ◽  
Hans Jørgen Henriksen ◽  
Julian Koch ◽  
Lars Troldborg ◽  
Simon Stisen
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Hydrological Model ◽  
Shallow Groundwater ◽  
Groundwater Table ◽  
Training Data ◽  
Computational Time ◽  
Hydrological Models ◽  
Shallow Groundwater Table ◽  
Induced Changes

<p>The DK-model (https://vandmodel.dk/in-english) is a national water resource model, covering all of Denmark. Its core is a distributed, integrated surface-subsurface hydrological model in 500m horizontal resolution. With recent efforts, a version at a higher resolution of 100m was created. The higher resolution was, amongst others, desired by end-users and to better represent surface and surface-near phenomena such as the location of the uppermost groundwater table. Being presently located close to the surface across substantial parts of the country and partly expected to rise, the groundwater table and its future development due to climate change is of great interest. A rising groundwater table is associated with potential risks for infrastructure, agriculture and ecosystems. However, the 25-fold jump in resolution of the hydrological model also increases the computational effort. Hence, it was deemed unfeasible to run the 100m resolution hydrological model nation-wide with an ensemble of climate models to evaluate climate change impact. The full ensemble run could only be performed with the 500m version of the model. To still produce the desired outputs at 100m resolution, a downscaling method was applied as described in the following.</p><p>Five selected subcatchment models covering around 9% of Denmark were run with five selected climate models at 100m resolution (using less than 3% of the computational time for hydrological models compared to a national, full ensemble run at 100m). Using the simulated changes at 100m resolution from those models as training data, combined with a set of covariates including the simulated changes in 500m resolution, Random Forest (RF) algorithms were trained to downscale simulated changes from 500m to 100m.</p><p>Generalizing the trained RF algorithms, Denmark-wide maps of expected climate change induced changes to the shallow groundwater table at 100m resolution were modelled. To verify the downscaling results, amongst others, the RF algorithms were successfully validated against results from a sixth hydrological subcatchment model at 100m resolution not used in training the algorithms.</p><p>The experience gained also opens for various other applications of similar algorithms where computational limitations inhibit running distributed hydrological models at fine resolutions: The results suggest the potential to downscale other model outputs that are desired at fine resolutions.</p>

scholarly journals Multivariate Analysis and Geochemical Signatures of Shallow Groundwater in the Main Urban Area of Chongqing, Southwestern China

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2833
Author(s):  
Si Chen ◽  
Zhonghua Tang ◽  
Jian Wang ◽  
Jialing Wu ◽  
Chang Yang ◽  
...  
Keyword(s):  
Geochemical Modeling ◽  
Shallow Groundwater ◽  
Poor Quality ◽  
Easy Access ◽  
Multivariate Statistical ◽  
Drinking Purposes ◽  
Groundwater Samples ◽  
New Findings ◽  
Group 2 ◽  
Group 1

Hydrogeochemical processes and quality assessment for shallow groundwater are pivotal issues to be solved in many regions over the world due to the easy access of shallow groundwater. In this study, eighty-six water samples were collected from shallow aquifers of Chongqing, China, during July–September 2019. Multivariate statistical techniques, major ion ratios, and geochemical modeling were integrated to investigate hydrogeochemical characteristics and controlling factors. Afterwards, groundwater quality in spatial was classified by entropy-weighted water quality index and geographic information system (GIS) spatial analysis. Groundwater samples were alkaline and possessed high total dissolved solids (TDS) values. Two-group samples were distinguished as mix cations-HCO3-SO4 (group 1) and Ca-Mg-SO4 (group 2) facies. Hydrogeochemical compositions of group 1 samples were dominated by silicate dissolution and ion exchange, while sulfate and calcite dissolution were the main factors influencing the hydrogeochemical characteristics of group 2. The overall quality of groundwater samples varied greatly from excellent quality to extremely poor quality. Group 1 samples were found with excellent and good quality and suitable for drinking purposes. Group 2 samples were all unsuitable for direct drinking purposes as the quality varied from medium to extremely poor, but were spatially limited. Groundwaters with relatively poor quality were due to dissolution of sulfate that were locally enriched in the aquifers. The new findings of this study are expected to provide the reference for future management and sustainable exploitation of groundwater in Chongqing.

scholarly journals Rethinking settlements in arid environments: case study from Uzbekistan

2019 ◽  
Vol 97 ◽  
pp. 05052 ◽  
Author(s):  
Akmal Karimov ◽  
Abdulkhakim Salokhiddinov ◽  
Inna Gracheva ◽  
Ravshan Umurzakov ◽  
Qadyr Artykov
Keyword(s):  
Groundwater Modeling ◽  
Shallow Groundwater ◽  
Arid Environments ◽  
Management Plans ◽  
Water Management Plans ◽  
Middle Stream ◽  
Development Plans ◽  
Quality Water ◽  
Basin Water ◽  
Shallow Groundwater Table

Fast growing population of Uzbekistan and increasing the share of urban citizens increased inter-linkages between settlements and irrigated farming. Growing settlements on account of farm land, increasing the demand for high quality water, wastewater utilization in agriculture, water logging and salinization are some of the water related inter-linkages. This paper focus on waterlogging issue at three different sites, located in the upstream of the Syrdarya River in Fergana Valley, middle stream of river in Mirzachul Steppe and the downstream of Amudarya River in Khorezm region. Groundwater modeling applied to examine different strategies of to lower shallow groundwater table. The results of the modeling studies indicate that ultimate solution for waterlogging issue can be achieved when basin water management plans linked with settlement development plans.

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