Boyka Mihaylova, Thomas Kerestedjian, Antoaneta Peneva, Aleksey Benderev
One of the goals of the study is to establish the conditions that affect the water quality in the catchment area of the Mesta River (Southwest Bulgaria). This will help to distinguish the anthropogenic impact from natural factors, with geological setting in first place. For the formation of the chemical composition of the waters in regional aspect, the outcropped rocks are of major importance. In the considered area most widespread are mainly silicate rocks – about 75% of the total area. These are mainly different types of granites and to a much lesser extent granodiorites, quartz porphyries, quartz porphyrites (58%). Highly metamorphosed rocks such as gneisses, shales, amphibolites are also important – 26%, as well as volcanic (rhyodacites, dacites, ignimbrites and their tuffs) – 5%. These rocks occupy the relatively higher and steeper parts of the catchment area and fractured rocks aquifers are formed in their weathering zones. Given the low solubility of the minerals forming these rocks and their rapid runoff, the waters in them show low TDS content. Due to the processes of chemical weathering, they provide some of the main macrocomponents, determining the chemical type of groundwaters – Na, Ca, Mg, HCO3. Although with a relatively small area (about 5%), the marbles, which are significantly karstified are characterized by the formation of large amounts of water. Active karst processes are the cause for the predomination of hydrogencarbonate-calcium type of waters. Neozoic sandstones, conglomerates and clays (about 8% of the total area) are deposited in lower parts of the river valley, in the range of tectonic grabens. They form a layered aquifer complex, where due to the slower movement of water and longer water-rock contact, groundwater has a relatively higher TDS content. Along with the regional hydrogeological and hydrochemical features, the geological setting is the reason for the probable presence of local hydrochemical anomalies. They are often associated with fractures and pegmatite veins, in which ore manifestations and indications of Pb, Zn, Cu, Fe, W, Mo, Ag, Au, Bi, Sb, as well as talc, asbestos and muscovite have been found. Elevated contents of Fe, Mn and U are found in some places too. The localization of such zones (over 100 in total) will help to correctly clarify the genesis of undesirable deviations in groundwater quality. Thermal water deposits, some of which have conditions for mixing with cold groundwater, are also examined.
{"title":"Geological factors for the formation of the chemical composition of groundwater in the catchment area of the Mesta river","authors":"Boyka Mihaylova, Thomas Kerestedjian, Antoaneta Peneva, Aleksey Benderev","doi":"10.52321/igh.37.1.61","DOIUrl":"https://doi.org/10.52321/igh.37.1.61","url":null,"abstract":"One of the goals of the study is to establish the conditions that affect the water quality in the catchment area of the Mesta River (Southwest Bulgaria). This will help to distinguish the anthropogenic impact from natural factors, with geological setting in first place. For the formation of the chemical composition of the waters in regional aspect, the outcropped rocks are of major importance. In the considered area most widespread are mainly silicate rocks – about 75% of the total area. These are mainly different types of granites and to a much lesser extent granodiorites, quartz porphyries, quartz porphyrites (58%). Highly metamorphosed rocks such as gneisses, shales, amphibolites are also important – 26%, as well as volcanic (rhyodacites, dacites, ignimbrites and their tuffs) – 5%. These rocks occupy the relatively higher and steeper parts of the catchment area and fractured rocks aquifers are formed in their weathering zones. Given the low solubility of the minerals forming these rocks and their rapid runoff, the waters in them show low TDS content. Due to the processes of chemical weathering, they provide some of the main macrocomponents, determining the chemical type of groundwaters – Na, Ca, Mg, HCO3. Although with a relatively small area (about 5%), the marbles, which are significantly karstified are characterized by the formation of large amounts of water. Active karst processes are the cause for the predomination of hydrogencarbonate-calcium type of waters. Neozoic sandstones, conglomerates and clays (about 8% of the total area) are deposited in lower parts of the river valley, in the range of tectonic grabens. They form a layered aquifer complex, where due to the slower movement of water and longer water-rock contact, groundwater has a relatively higher TDS content. Along with the regional hydrogeological and hydrochemical features, the geological setting is the reason for the probable presence of local hydrochemical anomalies. They are often associated with fractures and pegmatite veins, in which ore manifestations and indications of Pb, Zn, Cu, Fe, W, Mo, Ag, Au, Bi, Sb, as well as talc, asbestos and muscovite have been found. Elevated contents of Fe, Mn and U are found in some places too. The localization of such zones (over 100 in total) will help to correctly clarify the genesis of undesirable deviations in groundwater quality. Thermal water deposits, some of which have conditions for mixing with cold groundwater, are also examined.","PeriodicalId":479640,"journal":{"name":"Inženerna geologiâ i hidrogeologiâ","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135453025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rainfall erosivity is a crucial factor influencing soil erosion, which results from the detachment, transportation, and deposition of soil particles caused by rainfall and runoff. Rainfall erosivity assessment is a fundamental process aimed at quantifying the erosive power of rainfall events in a given region. The paper provides an overview of rainfall erosivity assessment in several heterogeneous regions of the Republic of North Macedonia based on rainfall data from meteorological stations characterized by different climatic and geographical conditions. Having into consideration that rainfall erosivity can be quantified by using various indices, this study uses two common ones: Fournier Index (FI) and the Modified Fournier Index (MFI) based on monthly and annual precipitation totals for the period 1951-2020. The results imply that in general, the studied stations belong to a low class of erosivity. It is found that FI has greater sensitivity and provides more details, also showing years with high and even very high rainfall erosivity while MFI gives more information for moderate rainfall erosivity.
{"title":"Rainfall erosivity in the Republic of North Macedonia: Fournier index approach","authors":"Imеrlije Alili","doi":"10.52321/igh.37.1.89","DOIUrl":"https://doi.org/10.52321/igh.37.1.89","url":null,"abstract":"Rainfall erosivity is a crucial factor influencing soil erosion, which results from the detachment, transportation, and deposition of soil particles caused by rainfall and runoff. Rainfall erosivity assessment is a fundamental process aimed at quantifying the erosive power of rainfall events in a given region. The paper provides an overview of rainfall erosivity assessment in several heterogeneous regions of the Republic of North Macedonia based on rainfall data from meteorological stations characterized by different climatic and geographical conditions. Having into consideration that rainfall erosivity can be quantified by using various indices, this study uses two common ones: Fournier Index (FI) and the Modified Fournier Index (MFI) based on monthly and annual precipitation totals for the period 1951-2020. The results imply that in general, the studied stations belong to a low class of erosivity. It is found that FI has greater sensitivity and provides more details, also showing years with high and even very high rainfall erosivity while MFI gives more information for moderate rainfall erosivity.","PeriodicalId":479640,"journal":{"name":"Inženerna geologiâ i hidrogeologiâ","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135453027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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