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Võrtsjärve hüdroloogilise seire analüüs

Pärnaku, Lauri (2019) Võrtsjärve hüdroloogilise seire analüüs. [thesis] [en] Lake Võrtsjärv Hydrological Monitoring Analysis.

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Abstract

Hüdroloogiline uuring kogub erinevaid andmeid veekeskkonna kohta. Keskkonnagentuuri hüdroloogiaosakond teostab, töötleb, salvestab ja levitab kogutud andmeid. Kogutud andmetest saab teha ka prognoose ja arvutusi. Järved on üldiselt suure tähtsusega inimeste jaoks kuna varustavad meid veega mida me kasutame põllumajanduses, tööstuses kui ka koduses majapidamises. Veekogud ei varusta meid ainult veega vaid ka toiduga kalade näol. Kuigi magevesi on meile üüratult vajalik siis toimub ikkagi veekogude reostus inimeste poolt, mis põhjustavad veekogus ökoloogilisi muudatusi. Järvede ja tiikide ökosüsteemid saavad kahjustada erinevate inimtegurite tõttu nagu näiteks suurenenud toitainete hulgad vees, veekogu saastamine, happevihmad kui ka võõrliikide sissetoomine. Veekogus toimuvatest muutustest saab aru tehes seiret läbi pikaajalise perioodi. Võrtsjärve seire toimub alates aastast 1954, kui sinna rajati limnoloogiajaam. Igakuist järve seiret tehakse aastast 1965 ning alates 1994 on Võrtsjärve seire riikliku keskkonnaseire programmi osa. Võrtsjärve seire eesmärgiks on teabe saamine järve hüdrokeemilise ja hüdrobioloogilise seisundi kohta kohta kui ka pikaajaliste protsesside selgitamiseks ning muutuste ja kriisiolukordade prognoosimiseks. Võrtsjärve seisund on aastatega paranenud. Peamised tegurid, mis mõjutavad veekogu, on seotud jääkattega ning muutustes veetasemes. Järv on mõjutatud oma suure pindala ja madala sügavuse tõttu tugevasti mõjutatud füüsikaliste (päikesevalgus, temperatuur, tuul, pH) tegurite poolt. Oma osa on ka inimteguritel. Lähedal asuvad farmid, põllumaad ning asulad mõjutavad veekogu lisatoitainetega, mis põhjustab taimede kiire kasvamise ehk eutrofeerumise. Seire tulemustest on näha, et mitmed näitajad on omavahel korreleerunud.

Abstract [en]

Hydrological study collects different data about aquatic environment. Estonian Environmental Agency's Department of Hydrology carries out, processes, saves and spreads collected data. From collected data forecast and calculations can be done. Lakes are usually with great importance for people because they supply us with water that we use in agriculture, industry and in domestic households. Water bodies do not supply us only with water but also with food in form of fish. Though fresh water is of great importance, water pollution still occurs because of people, which cause ecological changes in water bodies. Lakes and pond ecosystems are mostly damaged by different human factors such as increased nutrient levels, pollution, acid rain and introduction of alien species. Changes in water bodies can be detected by sustaining long term monitoring programs. Water quality monitoring in lake Võrtsjärv started in year 1954 when Limnology Station was built. Monthly monitoring has been done since 1965 and since 1994 lake Võrtsjärv monitoring is part of national environmental monitoring program. Purpose of Lake Võrtsjärv monitoring program is to get information about lake's hydrochemical and hydrobiological conditions, observe long term processes and forecast changes and crisis situations. Data from 1995 to 2018 was collected to make a comparison how lake's condition has changed over the years. 12 different indicators were chosen, 5 belong to hydrobiological category (phytoplankton biomass, cyanobacteria biomass, diatom biomass, number of phytoplankton species and quantity of chlorophyll) and 7 belong to physico-chemical category (chemcial oxygen demand, biochemcial oxygen demand, total phosphorus, total nitrogen, alkanity, pH and water transparency). Condition of lake Võrtsjärv shows signs of improvement over the years. All hydrobiological indicators have shown increase in levels. Majority of physico-chemical indicators have decreased. Only pH, alkalinity and chemical oxygen demand have increased. Main factors, which affect the water body, are related to ice cover and changes in water level. Lake with it's large area and low 29 depth is strongly affected by physical factors (sunlight, temperature, wind and pH). Human factors are important aswell. Nearby farms, arable land and settlements affect water body with extra nutrients, which will cause rapid growth of plants or eutrophication. From the results of monitoring the lake it can be seen that many indicators are correlated.

Item Type: thesis
Advisor: Oliver Kalda
Subjects: Technoecology > Environmental Protection > Environmental Monitoring
Divisions: Institute of Circular Economy and Technology > Environmental Technology and Management
Depositing User: Lauri Pärnaku
Date Deposited: 04 Jun 2019 13:13
Last Modified: 26 Aug 2019 12:18
URI: http://eprints.tktk.ee/id/eprint/4333

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