Estimation of climate change impacts on hydrology and floods in Finland

Noora Veijalainen

Estimation of climate change impacts on hydrology and floods in Finland

Julkaisun otsikon käännös: Ilmastonmuutoksen vaikutukset hydrologiaan ja tulviin Suomessa

Noora Veijalainen

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Ilmastonmuutoksen myötä ilman lämpötilan ja sadannan ennakoidaan kasvavan Suomessa 2000-luvulla, millä tulee olemaan selviä vaikutuksia hydrologiaan. Tässä väitöskirjassa arvioidaan ilmastonmuutoksen vaikutuksia hydrologiaan ja tulviin Suomessa käyttäen hydrologista mallintamista ja useita ilmastoskenaarioita. Yhtenä tavoitteena on ymmärtää miten eri prosessit ja valuma-alueiden ominaisuudet vaikuttavat ilmastonmuutoksen aiheuttamiin hydrologisiin muutoksiin boreaalisissa olosuhteissa. Ilmastonmuutoksen vaikutusten arviointiin käytettiin Vesistömallijärjestelmän (WSFS) konseptuaalista hydrologista mallia. Arviointia varten ilmastonmuutossignaali siirrettiin ilmastomallista hydrologiseen malliin käyttäen kahta menetelmää (delta change-menetelmä ja suorat korjatut alueellisen ilmastomallin tulokset) ja menetelmien tuloksia vertailtiin keskenään. Suoria alueellisten ilmastomallien tuloksia käytettiin simuloitaessa jatkuvia hydrologisia skenaarioita jaksolle 1951–2100 ja skenaarioista analysoitiin vesitaseen osatekijöiden muuttumista ja virtaama-aikasarjojen trendejä. Tutkimusten tulokset osoittavat, että ilmastonmuutoksen selvimmät vaikutukset ovat muutokset eri vuodenaikojen virtaamissa. Ilmastonmuutoksen aiheuttama ilman lämpötilan nousu vaikuttaa lumen kertymiseen ja sulamiseen, mikä kasvattaa talviajan virtaamia sekä pienentää lumen kevätsulannan aiheuttamia virtaamia. Muutokset kerran 100 vuodessa toistuvissa tulvissa jaksolla 2070–2099 vaihtelivat huomattavasti riippuen valuma-alueen sijainnista ja ominaisuuksista sekä tulvien ajoituksesta ja käytetystä ilmastoskenaariosta. Kevään lumen sulamistulvat pienenivät tai pysyivät nykyisen suuruisina, kun taas syksyn ja talven vesisateesta aiheutuvat tulvat kasvoivat etenkin suurissa järvissä ja niiden laskujoissa. Pitkän mallinnusketjun jokaiseen vaiheeseen liittyy epävarmuuksia, joten mallinnusprosessin aikana kertyvät epävarmuudet kasvavat suuriksi. Suuret erot eri ilmastoskenaarioiden tulosten välillä korostavat tarvetta käyttää useita ilmastoskenaarioita arvioitaessa ilmastonmuutoksen vaikutuksia. Tutkimuksessa arvioitiin myös mahdollisuuksia sopeutua ilmastonmuutoksen vaikutuksiin muuttamalla järvien säännöstelyä. Säännöstelyn uudelleenarviointi tulee tarpeelliseksi 2000-luvun aikana useilla Suomen säännöstelyillä järvillä, kun ilmastonmuutos aiheuttaa muutoksia järvien tulovirtaamissa.

Julkaisun otsikon käännös	Ilmastonmuutoksen vaikutukset hydrologiaan ja tulviin Suomessa
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Koivusalo, Harri, Vastuuprofessori Vehviläinen, Bertel, Ohjaaja, Ulkoinen henkilö Karvonen, Tuomo, Ohjaaja, Ulkoinen henkilö
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-4613-6
Sähköinen ISBN	978-952-60-4614-3
Tila	Julkaistu - 2012
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

hydrologinen mallintaminen
ilmastonmuutos
Suomen vesivarat
tulvat
vaikutusten arviointi
ilmastoskenaariot
sopeutuminen

YK:n kestävän kehityksen tavoitteet

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http://urn.fi/URN:ISBN:978-952-60-4614-3

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title = "Estimation of climate change impacts on hydrology and floods in Finland",

abstract = "Climate scenarios project increases in air temperature and precipitation in Finland during the 21st century and these will results in changes in hydrology. In this thesis climate change impacts on hydrology and floods in Finland were estimated with hydrological modelling and several climate scenarios. One of the goals was to understand the influence of different processes and catchment characteristics on the hydrological response to climate change in boreal conditions. The tool of the climate change impact assessment was the conceptual hydrological model WSFS (Watershed Simulation and Forecasting System). The studies employed and compared two methods of transferring the climate change signal from climate models to the WSFS hydrological model (delta change approach and direct bias corrected Regional Climate Model (RCM) data). Direct RCM data was used to simulate transient hydrological scenarios for 1951-2100 and the simulation results were analysed to detect changes in water balance components and trends in discharge series. The results revealed that seasonal changes in discharges in Finland were the clearest impacts of climate change. Air temperature increase will affect snow accumulation and melt, increase winter discharge and decrease spring snowmelt discharge. The impacts of climate change on floods in Finland by 2070-2099 varied considerably depending on the location, catchment characteristics, timing of the floods and climate scenario. Floods caused by spring snowmelt decreased or remained unchanged, whereas autumn and winter floods caused by precipitation increased especially in large lakes and their outflow rivers. Since estimation of climate change impacts includes uncertainties in every step of the long modelling process, the accumulated uncertainties by the end of the process become large. The large differences between results from different climate scenarios highlight the need to use several climate scenarios in climate change impact studies. Possibilities to adapt to climate change impacts through changes in lake regulation were also estimated. Changing the management and permits of many of the regulated lakes in Finland will become necessary during the 21st century in response to climate change induced shifts in hydrological regime.",

keywords = "hydrological modelling, climate change, water resources, floods, impact assessment, climate scenarios, adaptation, hydrologinen mallintaminen, ilmastonmuutos, Suomen vesivarat, tulvat, vaikutusten arviointi, ilmastoskenaariot, sopeutuminen, hydrological modelling, climate change, water resources, floods, impact assessment, climate scenarios, adaptation",

author = "Noora Veijalainen",

year = "2012",

language = "English",

isbn = "978-952-60-4613-6",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "55",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Estimation of climate change impacts on hydrology and floods in Finland

AU - Veijalainen, Noora

PY - 2012

Y1 - 2012

N2 - Climate scenarios project increases in air temperature and precipitation in Finland during the 21st century and these will results in changes in hydrology. In this thesis climate change impacts on hydrology and floods in Finland were estimated with hydrological modelling and several climate scenarios. One of the goals was to understand the influence of different processes and catchment characteristics on the hydrological response to climate change in boreal conditions. The tool of the climate change impact assessment was the conceptual hydrological model WSFS (Watershed Simulation and Forecasting System). The studies employed and compared two methods of transferring the climate change signal from climate models to the WSFS hydrological model (delta change approach and direct bias corrected Regional Climate Model (RCM) data). Direct RCM data was used to simulate transient hydrological scenarios for 1951-2100 and the simulation results were analysed to detect changes in water balance components and trends in discharge series. The results revealed that seasonal changes in discharges in Finland were the clearest impacts of climate change. Air temperature increase will affect snow accumulation and melt, increase winter discharge and decrease spring snowmelt discharge. The impacts of climate change on floods in Finland by 2070-2099 varied considerably depending on the location, catchment characteristics, timing of the floods and climate scenario. Floods caused by spring snowmelt decreased or remained unchanged, whereas autumn and winter floods caused by precipitation increased especially in large lakes and their outflow rivers. Since estimation of climate change impacts includes uncertainties in every step of the long modelling process, the accumulated uncertainties by the end of the process become large. The large differences between results from different climate scenarios highlight the need to use several climate scenarios in climate change impact studies. Possibilities to adapt to climate change impacts through changes in lake regulation were also estimated. Changing the management and permits of many of the regulated lakes in Finland will become necessary during the 21st century in response to climate change induced shifts in hydrological regime.

AB - Climate scenarios project increases in air temperature and precipitation in Finland during the 21st century and these will results in changes in hydrology. In this thesis climate change impacts on hydrology and floods in Finland were estimated with hydrological modelling and several climate scenarios. One of the goals was to understand the influence of different processes and catchment characteristics on the hydrological response to climate change in boreal conditions. The tool of the climate change impact assessment was the conceptual hydrological model WSFS (Watershed Simulation and Forecasting System). The studies employed and compared two methods of transferring the climate change signal from climate models to the WSFS hydrological model (delta change approach and direct bias corrected Regional Climate Model (RCM) data). Direct RCM data was used to simulate transient hydrological scenarios for 1951-2100 and the simulation results were analysed to detect changes in water balance components and trends in discharge series. The results revealed that seasonal changes in discharges in Finland were the clearest impacts of climate change. Air temperature increase will affect snow accumulation and melt, increase winter discharge and decrease spring snowmelt discharge. The impacts of climate change on floods in Finland by 2070-2099 varied considerably depending on the location, catchment characteristics, timing of the floods and climate scenario. Floods caused by spring snowmelt decreased or remained unchanged, whereas autumn and winter floods caused by precipitation increased especially in large lakes and their outflow rivers. Since estimation of climate change impacts includes uncertainties in every step of the long modelling process, the accumulated uncertainties by the end of the process become large. The large differences between results from different climate scenarios highlight the need to use several climate scenarios in climate change impact studies. Possibilities to adapt to climate change impacts through changes in lake regulation were also estimated. Changing the management and permits of many of the regulated lakes in Finland will become necessary during the 21st century in response to climate change induced shifts in hydrological regime.

KW - hydrological modelling

KW - climate change

KW - water resources

KW - floods

KW - impact assessment

KW - climate scenarios

KW - adaptation

KW - hydrologinen mallintaminen

KW - ilmastonmuutos

KW - Suomen vesivarat

KW - tulvat

KW - vaikutusten arviointi

KW - ilmastoskenaariot

KW - sopeutuminen

KW - hydrological modelling

KW - climate change

KW - water resources

KW - floods

KW - impact assessment

KW - climate scenarios

KW - adaptation

M3 - Doctoral Thesis

SN - 978-952-60-4613-6

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Estimation of climate change impacts on hydrology and floods in Finland

Abstrakti

Tutkimusalat

YK:n kestävän kehityksen tavoitteet

Pääsy asiakirjaan

Sormenjälki

Siteeraa tätä