Groundwater and surface water interactions in peatlands: hydrogeological insights from Estonian mires
Failid
Kuupäev
2024-09-09
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Sood on tähtsad ökosüsteemid meie maastikes. Nad on olulised elukohad taime- ja loomaliikidele ning ühtlasi ka suured pinnase süsinikuhoidlad ja maastike veerežiimi reguleerijad. Nende pindala on nii maailmas, kui ka Eestis, eelneva sajandi jooksul palju vähenenud, ennekõike kuivenduse mõjude tõttu. Põllumajanduslikud-, metsanduslikud- ja turbakaevandamise kuivendusmõjud on hästi teada ning uuritud. Vähem on teada sellest, kuidas mõjutab turba all olevate põhjaveekihtide kuivendamine veetasemeid soodes nende peal.
Käesolev doktoritöö loob selgust turba-aluste veekihtide kuivendamise mõjudest Selisoo näitel, mis asub Kirde-Eestis, vahetult töötava põlevkivi allmaakaevanduse kõrval. Veetasemete seire kaudu kinnitatakse, et põlevkivi kaevandamisest tingitud veetasemete alanmine põhjaveekihtides mõjutab ka raba veerežiimi, eriti just äärealadel, kus turbalasund on õhukesem. Sellest tulenevalt uuritakse põhjalikumalt turba füüsikalisi omadusi ja veejuhtivusi ka teistes Kirde-Eesti soodes. Nähtavate seoste põhjal pakutakse välja kaks statistilist mudelit, millega ennustada veejuhtivust teiste mõõdetavate turba omaduste kaudu.
Lisaks pakutakse doktoritöös välja meetod, millega uurida turba vertikaalset veejuhtivust. Käsitletud metoodikat pole varasemalt turba puhul kasutatud, kuid esitletud tulemused näitavad, et välja pakutud võtetega on võimalik turba vertikaalset veejuhtivust hinnata. Doktoritöös saadud andmed ja välja pakutud meetod ning mudelid on olulised, saamaks laialdasemat ning detailsemat ülevaadet piirkonna soode hüdroloogiast. Kõik see on vajalik koostamaks täpsemaid hüdroloogilisi- ja hüdrogeoloogilisi mudeleid, et hinnata turba-aluste veekihtide kuivendamise mõjusid soodele.
Peatlands are important ecosystems in our landscapes. They serve as crucial habitats for plant and animal species, act as large soil carbon stores, and regulate the hydrology of landscapes. Their area has decreased over the past century both globally and in Estonia, primarily due to drainage that lowers water levels in peatlands. The drainage impacts from agriculture, forestry, and peat extraction are well-known and studied. However, less is known about how the drainage of underlying affects the water levels in peat. This dissertation investigates the impacts of underground drainage on a peatland using the example of Selisoo, located in northeastern Estonia, near an active oil shale underground mine. The water levels monitoring confirms that lowering of groundwater levels caused by mining, also affects the water regime of the bog, especially at bog margins where the peat layer is thinner. Consequently, this dissertation investigates the physical properties and hydraulic conductivity of peat in other bogs in northeastern Estonia. Based on the observed relationships, two statistical models are proposed to predict hydraulic conductivity using the peat properties discussed in the study. Additionally, the dissertation proposes a method for investigating the vertical hydraulic conductivity of peat. This methodology has not been previously used for peat, but the presented results indicate that it could be used to assess vertical conductivity. The obtained data and the proposed method and models are important for gaining a broader and more detailed understanding of the hydrology of bogs in the region. This is necessary for developing accurate hydrological and hydrogeological models to assess the impacts of drainage beneath the peat on these ecosystems.
Peatlands are important ecosystems in our landscapes. They serve as crucial habitats for plant and animal species, act as large soil carbon stores, and regulate the hydrology of landscapes. Their area has decreased over the past century both globally and in Estonia, primarily due to drainage that lowers water levels in peatlands. The drainage impacts from agriculture, forestry, and peat extraction are well-known and studied. However, less is known about how the drainage of underlying affects the water levels in peat. This dissertation investigates the impacts of underground drainage on a peatland using the example of Selisoo, located in northeastern Estonia, near an active oil shale underground mine. The water levels monitoring confirms that lowering of groundwater levels caused by mining, also affects the water regime of the bog, especially at bog margins where the peat layer is thinner. Consequently, this dissertation investigates the physical properties and hydraulic conductivity of peat in other bogs in northeastern Estonia. Based on the observed relationships, two statistical models are proposed to predict hydraulic conductivity using the peat properties discussed in the study. Additionally, the dissertation proposes a method for investigating the vertical hydraulic conductivity of peat. This methodology has not been previously used for peat, but the presented results indicate that it could be used to assess vertical conductivity. The obtained data and the proposed method and models are important for gaining a broader and more detailed understanding of the hydrology of bogs in the region. This is necessary for developing accurate hydrological and hydrogeological models to assess the impacts of drainage beneath the peat on these ecosystems.
Kirjeldus
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