Impact of climate change on water resources in pilot basins in Serbia
- results of the join RHMSS/NVE project -
Mirjam Vujadinovic and Ingjerd Haddeland
Part I : Regional climate models results
www.hidmet.rs www.seevccc.rs www.nve.com
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Impact of climate change on water resources in pilot basins in Serbia
- results of the join RHMSS/NVE project -
Ingjerd Haddeland Hege Hisdal
Elin Langsholt Deborah Lawrence
Wong Wai Kwok
Mihailo Andjelic Dejan Vladikovic
Slavimir Stevanovic
Marija Ivkovic Goran Pejanovic
Mirjam Vujadinovic
www.hidmet.rs www.seevccc.rs www.nve.com
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Background & Motivation • NVE and RHMSS have been project partners since 2005 in the field of hydrology, hydrological forecasting and water resources in Serbia, with financial support provided by the Norwegian Ministry of Foreign Affairs.
• Projects implemented through this partnership assisted RHMSS in acquiring modern technology and know how in such important areas as: hydrometry and stream measurements, optimization of hydrological network, introduction of a versatile hydrological information management system (WISKI 7), introduction of HBV rainfall-runoff model for operational hydrological forecasting and simulation in small catchments, study of climate change impact on river flow in two catchments in Serbia.
• Climate change is expected to have serious effect on water resources management in the South-East Europe. However, until now there was no water resources climate change impact studies in Serbia.
• Two pilot catchments with sufficient hydrological and climatological data were selected for the study: Toplica and Kolubara.
• Temperature and precipitation output from 6 regional climate models and 3 time slices were used: 1961-1990 (past climate, control period), 2001-2030 (near future), 2071-2100 (far future).
• Bias corrected timeseries were used as an input for HBV model runs.
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Pilot basin: Toplica
basin size: 2231 km2
topography: mainly bellow 800 masl with mountain peaks over 2000 masl
vegetation: fields & crops bellow 800 masl, forest above 800 masl
water regime: mixed snow & rain generated runoff
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Figure 2.9: Field and forest distribution in the Toplica catchment.
Figure 2.10: Location of three hydrometeorological stations in the Toplica catchment used in the study.
hydorolgical station: Doljevac climatological stations: Kursumlija and Nis
Pilot basin: Kolubara topography: mainly bellow 400 masl with low (up to 1000 masl) and medium-high mountains (up to 1500 masl) in the most upstream part of the basin
vegetation: crops and meadows bellow 400 masl, orchards and forest above 600 masl
water regime: mixed rain and snow generated runoff
location: 19°37’ – 20°11’ E 44°05’ – 44°22’ N
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Historical climate and stream flow data for the period January 1985 - January 2010 have been used. There is only one climate station in the catchment (Valjevo, Figure 2.4) that has a time series long enough for this study. Four months of missing climate data in 1988, 1989 and 1990 at the Valjevo station ( located at 174 masl) were reconstructed by using observed data from the nearby RC Valjevo station ( located at 388 masl), as these two stations have a high correlation in both the precipitation and temperature data series.
Figure 2.4: Location of the three hydrometeorological stations in the Kolubara catchment used in the study.
The city of Valjevo has a moderate continental climate with certain peculiarities reflected in elements of sub-humid and micro-thermal climates. Precipitation is relatively evenly distributed over the seasons with an average annual precipitation of 765 mm and a maximum average monthly precipitation in June (Figure 2.5). Average temperature is close to zero in December and January and reaches 22-23 °C during the summer months. The area of Valjevo has on average 32 days of snow per year, whereas the snow cover lasts on average 43 days. Snowfall is normally seen in the catchment in December and January.
The Kolubara River and its tributaries have a mixed rainfall-snowmelt water regime. The highest runoff occurs in the period March-April, followed by moderate runoff in June and July. The driest months are August and September (Figure 2.6). An important feature of the stream flow regime is a very pronounced flow fluctuation resulting in a pronounced difference between minimum and maximum monthly mean discharge values. The hydrological station Slovac has five months of missing water level and discharge data in the period 2005 – 2006. The average discharge at Slovac in the observation period is 8.35 m3/s, corresponding to 266 mm/year of runoff, and the average yearly maximum discharge is 119 m3/s. Mean annual runoff is about 38 % of mean annual precipitation.
hydorolgical station: Slovac climatological station: Valjevo
basin size: 991 km2
Climate modeling
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Regional climate modeling benefits
Mean 2m temperature for winter season, time slice 1961-1990
Regional dynamical downscaling provides more detailed information on present climate and projected future climate changes
OBSE
RVAT
IONS
RE
GION
AL M
ODEL
GLOB
AL M
ODEL
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
GCM/RCM simulations
horizontal resolution: 0.25° (~30km)
domain: Europe, Euro-Mediterranean
time slices: 1961-1990, 2001-2030, 2071-2100 (or 2069-2098)
6 GMC/RCM simulations: 4 from ENSEMBLES project: http://ensemblesrt3.dmi.dk/ 2 from SEEVCC & Belgrade Univ.: http://www.seevccc.rs/?p=18
IPCC/SRES scenario: A1B daily output: 2 m temperature, precipitation
GCM RCM Ins)tu)on Project
ECHAM4 RCM-‐SEEVCCC UB&SEEVCCC SINTA
ECHAM5 RCM-‐SEEVCCC UB&SEEVCCC Min. of Science of R. Serbia, 43007
ECHAM5 HIRHAM5 DMI ENSEMBLES
ECHAM5 RegCM3 ICTP ENSEMBLES
HadCM3Q0 HadRM3Q0 Hadley Centre ENSEMBLES
HadCM3Q0 CLM ETHZ ENSEMBLES
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Statistical BIAS correction
2mTemp. difference between simulation and observations (summer 1981-2000)
Image from CLAVIER-WP1: Climate
Summer Drying Problem (CLAVIER project): “The most severe systematic error relevant for the CLAVIER domain is known as the Summer Drying Problem and is characterized by the too dry and too warm simulation of climate over Central and Eastern Europe during summer [Hagemann et al. 2004, Jacob et al., 2008]. It is typical for many regional and also some global climate models.”
Climate change impact studies require a statistical BIAS correction of model’s output.
Correction functions are made for daily 2m temperature and daily precipitation for each station and each month for period 1961-1990.
Idea: model results and observations from the same 30-years long period should have the same PDF.
Daily 2m temperature during one month: Normal distribution Daily precipitation during one month: Bernoulli- Gamma distribution,
special attention to number of dry days
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
model produces more drizzle
model underestimates high precipitation
Statistical BIAS correction: simple “how to”
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Statistical BIAS correction: verification example
monthly 2m temperature monthly acc. precipitation
Regional Workshop on Hydrological Forecasting and Impact of Climate Change on Water Resources
Projections: temperature
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Figure A.11: Distribution of monthly average temperatures at Niš for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
Projections: temperature
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Figure A.10: Distribution of monthly average temperatures at Kuršumlija for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
Projections: temperature
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Figure A.12: Distribution of monthly average temperatures at Valjevo for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
Projected changes: precipitation
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Figure A.14: Distribution of monthly precipitation at Niš for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
Projections: precipitation
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Figure A.13: Distribution of monthly precipitation at Kuršumlija for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
Projections: precipitation
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Figure A.15: Distribution of monthly precipitation at Valjevo for the three periods 1961-1990, 2001-2030, and 2069-2098 for all six projections, following bias correction.
2m temperature change [2071-2100]-[1961-1990]
acc. precipitation change [2071-2100]-[1961-1990]
Projected changes - seasonal
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Figure 4.8: Distribution of monthly total precipitation values at Valjevo for the three periods 1961-1990, 2001 - 2030, and 2071 – 2100 for the ech-ebupom projection, following bias correction of daily values on a monthly basis.
Table 4.3: Projected changes in average precipitation during the summer vs. winter half-year periods for each RCM projection at each of the three climate stations. The values given are for the change between the control period (1961-1990) and the future period (2069-2098 or 2071-2100).
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Table 4.2: Projected changes in average temperature during the summer vs. winter half-year periods for each RCM projection at each of the three climate stations. The values given are for the change between the control period (1961-1990) and the future period (2069-2098 or 2071-2100).
4.2.4 Projected changes in precipitation Projected changes in monthly precipitation can also be interpreted from the RCMs by comparing bias-corrected values for three periods: 1961-1990, 2001-2030 and 2069-2098 (or 2071-2100 for the two RCM-SEEVCCC runs). These are illustrated on a monthly basis for the bias corrected RCM data for Valjevo for the ech-ebupom projection in Figure 4.8. There is large variability in monthly precipitation both in the current and in the two future periods. This projection seems to indicate, however, a decrease in the median values for total monthly precipitation during the period May – October by the end of the 21st century. Changes during winter months are generally minimal, relative to the variability in individual months. Plots showing a similar comparison for the control and future periods for all of the projections for the three climate stations can be found in the Appendix (Fig. A13 – A15). Amongst these projections, the two RCMs based on the Hadley GCM (had-clm and had-hadrm) indicate notable decreases in monthly precipitation during the summer months at all three climate stations. Otherwise, changes are small relative to the overall variability in individual months. A summary of the projected changes in seasonal precipitation is given in Table 4.3 below and highlights the differences between the large decreases projected by the Hadley-driven RCMs and the smaller changes projected by other RCMs.
