Peculiarities of performance of experimental filtering works in sites subsoil operated by single water intakes

The article discusses the methods used in the field experimental filtration work, which allow you to gain knowledge about the filtration properties and water abundance of rocks. The features of the experimental filtration work in the subsoil areas operated by single water intakes are shown. It is noted that these are small water bodies, both in terms of the number of water wells and the amount of actual water withdrawal. The article proposes to use short-term single pumpings as a field research method in the above-mentioned areas, according to the results of which it is possible to substantiate the amount of required water withdrawal and determine the calculated values of the water conductivity coefficient. As an example, the results of pumping are considered, obtained during the implementation of experimental filtration work at three single water intakes located within the Latitude Ob region. The results of the experimental filtration work served as the source material for calculating the reserves of fresh groundwater. Fresh groundwater reserves were calculated and approved for each site in the amount of 499 m3/day for category B.

Groundwater quality assessment for irrigation use in the Godavari delta region of east coast India using IRWQI and GIS

The present work was carried out in the deltaic region of the river Godavari in Coastal Andhra Pradesh of Southern India to evaluate the status of groundwater quality for irrigation. Groundwater is predominantly used in these productive agricultural fields. Saline water intrusion in fresh groundwater aquifers was recorded in the study area which is mainly due to the excess withdrawal of groundwater. A total of 80 groundwater samples were analyzed for various physical and chemical parameters using standard chemical procedures. The groundwater mainly represents sodium-chloride type which exhibits the mixing of fresh water with the saline water. The high correlation between Na+-Cl− and Mg2+-HCO3− explained that the intermixing of aquifer waters and the leaching of secondary salts. The mechanisms of groundwater have been shown mainly evaporation-fractional crystallization process. The irrigation water quality index was calculated by using different quality indices such as Na%, SAR, RSBC, PI, MH, KR, PS, Cl−:HCO3−, Mg2+:Ca2+, and Na+:Ca2+ to estimate the suitability of groundwater quality for irrigation. Spatial distribution maps were prepared using raster interpolation in GIS. The assessment revealed that the areas covering 67.6% of electrical conductivity, 100% of total dissolved solids, 57.5% of percent sodium, 21.3% of residual sodium bicarbonate, 66.3% of permeable index, 16.3% of magnesium hazard, 65% of Kelly's ratio, 100% of potential salinity were required severe to moderate restrictions. Overall, the groundwater in the study region showed potential salinity due to geogenic and anthropogenic activities thus it must be monitored for sustainable agriculture.

Penentuan Daerah Imbuhan Dan Evaluasi Kualitas Air Tanah Pada Akuifer Tertekan Cekungan Air Tanah Baubau Di Kota Baubau

The increasing population followed by the development of industrial activities resulted in excessive exploitation of water and pollution of water sources. This research aims (1) to analyze the distribution of groundwater recharge areas, (2) to analyze the quality of groundwater; and (3) to analyze the effect of seawater intrusion on the Baubau CAT confined aquifer within the City of Baubau area. The analysis method used is (1) Determination of groundwater recharge areas is carried out based on Permen ESDM Number 31 of 2018 concerning Guidelines for Establishing Groundwater Conservation Zones, namely by identifying hydrogeological data, (2) The level of groundwater damage is analyzed based on groundwater quality, in accordance with ESDM Ministerial Regulation Number 31 of 2018 concerning Guidelines for Establishing Groundwater Conservation Zones; and (3) The level of seawater intrusion was classified using the Davis and de Weist method. The results of this study are (1) The distribution of recharge areas covers 43% of the land area of the City of Baubau or an area of 96 km². The recharge area is an area of low hills, hills and high hills with an altitude of 100 to 700 meters above sea level. (2) The level of groundwater damage based on TSD and DHL values is that there are 7 drilled wells that are still in the safe category, while the other 2 bore wells are in the vulnerable category; (3) Groundwater in confined aquifers in the study area has not shown the influence of sea water intrusion with DHL values ranging from 773 µS cmˉˡ to 1,402 µS cmˉˡ and is categorized as fresh groundwater where the DHL values are still in the range of 30 - 2,000 µS cmˉˡ. Keywords: groundwater, groundwater quality, seawater intrusionJumlah penduduk yang meningkat dan diikuti dengan berkembangnya aktivitas industri mengakibatkan eksploitasi air berlebih dan pencemaran sumber air. Peneltian ini bertujuan (1) untuk menganalisis sebaran daerah imbuhan air tanah, (2) menganalisis kualitas air tanah; dan (3) menganalisis pengaruh intrusi air laut pada akuifer tertekan CAT Baubau dalam wilayah Kota Baubau. Metode analisis yang digunakan yaitu (1) Penentuan daerah imbuhan air tanah dilakukan berdasarkan Permen ESDM Nomor 31 Tahun 2018 Tentang Pedoman Penetapan Zona Konservasi Air Tanah yaitu dengan melakukan identifikasi data hidrogeologi, (2) Tingkat kerusakan air tanah dianalisa berdasarkan kualitas air tanah, sesuai dengan Permen ESDM Nomor 31 Tahun 2018 Tentang Pedoman Penetapan Zona Konservasi Air Tanah; dan (3) Klasifikasi tingkat intrusi air laut dilakukan dengan metode Davis and de Weist. Hasil penelitian ini yaitu (1) Sebaran daerah imbuhan tersebut meliputi 43 % dari luas daratan Kota Baubau atau seluas 96 km². Daerah imbuhan tersebut merupakan wilayah perbukitan rendah, perbukitan dan perbukitan tinggi dengan ketinggian 100 hingga 700 meter di atas permukaan laut. (2) Tingkat kerusakan air tanah berdasarkan nilai TSD dan DHL adalah terdapat 7 sumur bor masih dalam kategori aman, sedangkan 2 sumur bor lainnya masuk dalam kategori rawan; (3) Air tanah pada akuifer tertekan di daerah penelitian belum memnunjukkan adanya pengaruh intrusi air laut dengan nilai DHL berkisar antara 773 µS cmˉˡ hingga 1.402 µS cmˉˡ dan dikategorikan sebagai air tanah segar dimana nilai DHL masih berada dalam kisaran 30 – 2.000 µS cmˉˡ. Kata Kunci : air tanah, kualitas air tanah, intrusi air laut

Influence of Saltwater Submergence on Geohydraulic Properties of Sand: A Laboratory Investigation

Saline water intrusion into freshwater aquifers is a major geohydraulic problem relevant to coastal environment. Apart from contaminating the fresh groundwater resources, the saltwater intrusion alters the geotechnical properties of the aquifer materials, affecting the coastal water resource planning and management. The present study focuses on an in-depth laboratory investigation of the influence of saltwater submergence on the geohydraulic properties of sand. The fine sand sample was submerged under saline water of specified concentrations for specific periods, and the alteration in their engineering properties has been studied. It is observed that the specific gravity, dry density, and permeability of fine sand is significantly affected by the period of submergence and saline concentration. The specific gravity of sand particles was observed to increase almost linearly with period of submergence and saline concentration. While the sand dry density decreased fairly linearly with the period of submergence, the same is not being affected significantly by saline concentration. The permeability of sand increased nonlinearly with both period of submergence and saline concentration; for a submergence period of 14 days and saline concentration of 30,000 ppm, the permeability increased to a maximum value.

Offshore fresh groundwater in coastal unconsolidated sediment systems as a potential fresh water source in the 21st century

Coastal areas worldwide are often densely populated and host regional agricultural and industrial hubs. Strict water quality requirements for agricultural, industrial and domestic use are often not satisfied by surface waters in coastal areas and consequently lead to over-exploitation of local fresh groundwater resources. Additional pressure by both climate change and population growth further intensifies the upcoming water stress and raise the urgency to search for new fresh water sources. In recent years, offshore fresh groundwater reserves have been identified as such a potential water source. In this study, we quantify, for the first time, the global volume of offshore fresh groundwater in unconsolidated coastal aquifers and show that it is a viable option as additional fresh water source in coastal areas. Our results confirm previously reported widespread presence of offshore fresh groundwater along the global coastline. Furthermore, we find that these reserves are likely non-renewable as they were deposited during glacial periods when sea levels were substantially lower compared to current sea level. We estimate the total offshore fresh groundwater volume in unconsolidated coastal aquifers to be approximately 1.06 ± 0.2 million km³, which is roughly three times more than estimated previously and about 10% of all terrestrial fresh groundwater. With extensive active and inactive offshore oil pumping present in areas of large offshore fresh groundwater reserves, they could be considered for temporary fresh groundwater exploration as part of a transition to sustainable water use in coastal areas on the long run.

Coastal Groundwater Dynamics - Investigation of Using Geoelectrical and Hydrochemical Tools for Saline Intrusion Monitoring

<p>With over 65 % of the global population currently living in areas near a coast, increasing fresh groundwater demands within these areas, shifted precipitation patterns, and rising mean sea levels, increased seawater intrusion into coastal aquifers has become a major issue for groundwater resources in many coastal countries all around the world. Although there are many past studies researching the saline interface in affected aquifers from a modelling, laboratory or field perspective with different hydrological and geophysical approaches, little is known about real field dynamics over various time spans and in different geological settings. This PhD project aims at detecting and characterising seawater intrusion into a shallow coastal Holocene sand and gravel aquifer at New Zealand's west coast with respect to seasonally changing aquifer resistivity and hydrochemical tracers, as well as investigating resistivity and hydraulic property changes within a tidal time frame. Seawater mixing behaviour over different time spans was monitored with electrical resistivity tomography (ERT) over the course of two years, and additional hydrochemical sampling was carried out during the second year of the long-term seawater intrusion monitoring study. During two consecutive years, repeat ERT measurements were able to determine seasonal and shorter-term cycles in seawater mixing behaviour within the shallow coastal aquifer. There are strong indications that increasing urbanisation has a major influence on seasonal seawater intrusion patterns, and the dominant processes at the field locations were identified to be tied to the amount of freshwater available over the course of a year, as well as enhanced evapotranspiration / evaporation during summer. Hydrochemical data backed these observations and were also able to characterise seawater intrusion as a function of depth at the field location. Within the smaller tidal cycle investigations, similarly behaving parts of the aquifer could be identified from resistivity ratios and time series analyses. Varying amplitudes in resistivity changes led to the conclusion that saline mixing within a diurnal tidal cycle is strongly dependent on the recharge regime of the aquifer and decreases significantly for times during the year when recharge is continuous as opposed to times with little general recharge but intense, isolated rainfall events. In addition, tidal time series were used to qualitatively infer hydraulic properties of the aquifer and ultimately delineate preferential flow paths for seawater intrusion at the field site. The results of this project support findings of previous modelling, laboratory and short-term field studies, and put the concepts into a much broader time frame. For the first time the dynamics of seawater mixing in a shallow coastal sand aquifer were conclusively studied at the same location and within different time frames, and are thus of great value for sustainable groundwater management in the area of investigation and similar coastal environments.</p>

Coastal Groundwater Dynamics - Investigation of Using Geoelectrical and Hydrochemical Tools for Saline Intrusion Monitoring

<p>With over 65 % of the global population currently living in areas near a coast, increasing fresh groundwater demands within these areas, shifted precipitation patterns, and rising mean sea levels, increased seawater intrusion into coastal aquifers has become a major issue for groundwater resources in many coastal countries all around the world. Although there are many past studies researching the saline interface in affected aquifers from a modelling, laboratory or field perspective with different hydrological and geophysical approaches, little is known about real field dynamics over various time spans and in different geological settings. This PhD project aims at detecting and characterising seawater intrusion into a shallow coastal Holocene sand and gravel aquifer at New Zealand's west coast with respect to seasonally changing aquifer resistivity and hydrochemical tracers, as well as investigating resistivity and hydraulic property changes within a tidal time frame. Seawater mixing behaviour over different time spans was monitored with electrical resistivity tomography (ERT) over the course of two years, and additional hydrochemical sampling was carried out during the second year of the long-term seawater intrusion monitoring study. During two consecutive years, repeat ERT measurements were able to determine seasonal and shorter-term cycles in seawater mixing behaviour within the shallow coastal aquifer. There are strong indications that increasing urbanisation has a major influence on seasonal seawater intrusion patterns, and the dominant processes at the field locations were identified to be tied to the amount of freshwater available over the course of a year, as well as enhanced evapotranspiration / evaporation during summer. Hydrochemical data backed these observations and were also able to characterise seawater intrusion as a function of depth at the field location. Within the smaller tidal cycle investigations, similarly behaving parts of the aquifer could be identified from resistivity ratios and time series analyses. Varying amplitudes in resistivity changes led to the conclusion that saline mixing within a diurnal tidal cycle is strongly dependent on the recharge regime of the aquifer and decreases significantly for times during the year when recharge is continuous as opposed to times with little general recharge but intense, isolated rainfall events. In addition, tidal time series were used to qualitatively infer hydraulic properties of the aquifer and ultimately delineate preferential flow paths for seawater intrusion at the field site. The results of this project support findings of previous modelling, laboratory and short-term field studies, and put the concepts into a much broader time frame. For the first time the dynamics of seawater mixing in a shallow coastal sand aquifer were conclusively studied at the same location and within different time frames, and are thus of great value for sustainable groundwater management in the area of investigation and similar coastal environments.</p>

Current and future state of groundwater salinization of the northern Elbe-Weser region

Salinization of the upper aquifer of the northern Elbe-Weser region almost extends to the surface. Chloride content exceeds 250 mg/l and the groundwater is therefore, according to the German Drinking Water Ordinance, not suitable as drinking water. The chloride content in the aquifer originates from early flooding with seawater which occurred during the Holocene sea level rise. Depth and extent of the salinization were mapped by airborne electromagnetic surveys and validated by groundwater analyses. In the transition zone between the marshlands and geest areas, the fresh-saline groundwater interface falls to a depth of > −175 m NHN. Due to the extensive drainage of the marshlands, seepage of fresh groundwater is impeded. Instead, an upconing of the fresh-saline groundwater interface appears due to an upwardly directed hydraulic gradient. Due to climate change, chloride concentrations will increase along the coastlines. Further inland, a decrease of chloride content in near-surface groundwater will occur.

Spatial Distribution of Grain Size Within Nitraria retusa Coppice Dune in Kuwait

Nabkhas are desert and sabkha perennial plants that form stabilized dunes. A total of 23 sediment samples were taken from the surface and subsurface (30 cm depth) of nabkha that formed around Nitraria retusa as the dominant perennial plant species in Ghudai-Kuwait. The morphological and ecological functions of sabkha nabkha are distinguishable. The existence of shallow fresh groundwater that floats atop the saline water bodies and is recharged by rainwater and surface drainage routes is due to the presence of thriving nabkhas within a salty sabkha environment. the selected non-protected Nitraria nebkhas have an elongated dome shape with a height of 1.30 m and an average length of 11.80 m. also, the greatest distances between isolated nabkhas are found in Nitraria dominated coppice dunes. There are three types of Nitraria dominated coppice dunes, namely: single (one plant), coupled (two plants), and complex (three or more). Nitraria is considered one of Kuwait’s most effective plant species for trapping mobile sand, Nitraria can to tarp to 21 m3 of mobile sand and dust. The variations in grain size sediments in Nitraria retusa between surface and root zone, border and crest, upwind and downwind, are efficient for retaining water. Furthermore, Nitraria retusa from the sabkha environment is the most effective in collecting mobile sand in the region.

Interaction of fresh and submarine saline groundwater in the coastal zone of the Sea of Okhotsk and the Sea of Japan

The multidirectional interaction of fresh groundwater of land with a mineralization of 0.1 - 0.2 g/dm3 and submarine saline groundwater in the coastal zone of the western coast of the Sea of Okhotsk and the Sea of Japan has been characterized. The main hydrochemical background in the coastal zone of the seas is created by ultra-fresh and fresh hydrocarbonate groundwater of land in the free gravity runoff zone. The main types of submarine groundwater are silt sediment waters, pore-stratal and fissure-stratal waters of sedimentary rocks, fissure and fissure-vein waters of effusive, metamorphic and intrusive rocks. With the salinity of the modern sea waters within the range of 30-34.4 g/dm3, a decrease is traced from 27-30 g/dm3 in the sediments of the Upper Miocene-Holocene aquifer complex to 14-20 g/dm3 in the sediments of the Oligocene-Lower Miocene complex. Fresh groundwater of volcanogenic hydrogeological basins, the deposits of which have been explored in basalts, are distinguished by special advantages. These waters do not have environmental restrictions for drinking, they belong to the highest class and their resources may well be involved for a worthy use within the region and beyond.