WP5: Climate change impacts in hydrology and water management
WP leader: dr. Rodica Mic (National Institute of Hydrology and Water Management, Bulgaria)


  • Analysis based on high resolution Regional Model outputs of the climate change impact on hydrological resources in the central and eastern Europe (NIHWM, CHMI, IAP, FRI).
  • Analyse of the climate change impact on the flood events (CHMI).
  • Assessment of the managed water resources, demand and vulnerability and corresponding adaptation measures for present and projected climate (NIHWM, CHMI, IAP).
  • Assessment of impacts of the climate change on water quality: changes of nutrient (N, P) concentrations and eutrophication in a reference river network with reservoirs used for drinking water supply and recreation (IAP).
  • Study of the impacts of global change signal on local climate variability of air-sea coupled modes for the western Black Sea coast. (NMA, NIHWM).
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Description of work

For assessing the impact of the climate changes upon the water resources, the WATBAL model is used. This is a water balance with monthly time step model and it is combined with the Priesley-Taylor method for calculating the potential evapotranspiration. The analysed reference basins will be: Ialomita-Buzau area (19 040 km2) from Romania, Dyje river basin (17,800 km2) which are the tributaries of the Danube river, and Vltava basin (11 500 km2) from Czech Republic, and Hron river basin (5 465 km2).
The rainfall-runoff models to be used for the simulations will be applied in two cases: present climate and projected climate.

Consequently, the input meteorological data (precipitation and temperature) and the rainfallrunoff model parameters will be considered as averaged values over the basin area. Such requirement can only be accomplished provided the basin area is sufficiently small (a couple of hundreds of square kilometres). In order to calibrate the models the monthly river flows over the selected period (1970-2000) will be simulated. By applying the models in the reference basins, the monthly discharge hydrographs at the outlets will be calculated.

For estimation of hydrologic impact of climate change on Dyje catchment (a part of Danube river basin with area cca 11 500 km2), the rainfall-runoff model HYDROG will be used. The objective is to find out the hydrologic impact with the view of hydrologic extremes - mainly flood events. For this purpose the model will be recalibrated according to flood events of last years (especially large floods in August 2002 and snow-melting in March 2005). Then the comparative simulations of rainfall-runoff events according to the outputs of climatic model will be done. In order to assess the vulnerability of the water resources under the climate change conditions, monthly mean discharges series in several points of the reference basins will be necessary. These points represent the locations of water reservoirs, diversion and restitution works where the water resources - demands budgets are to be completed. The assessment of the monthly river flows in these points will be done by means of a correlation function between the station at the outlet of the reference basin and other gauging stations in the reference basins. The correlation function will be determined on the basis of the recorded data over a 30 years period at the gauging stations located in the reference basins. It is assumed that the correlation function between discharges in different points of the reference basins, determined for the current climate, maintains in the modified climatic scenario. The assessment of the vulnerability of water resources and corresponding adaptation measures will be made in the some reference basins.

An analysis of natural and man-induced variability of precipitation-runoff process and water quality in the river network will be done for a period of available water quality data (since the 1960s). Special attention will be given to water quality and eutrophication of reservoirs. On the other hand, a modelling system will be adopted to simulate precipitation-runoff processes and water quality with high temporal (day or sub-day intervals) and spatial (10- to 500-km2 segments in the catchment or 1 to 3 km longitudinal segments in reservoirs) resolution. Two major parts of the modelling system include (i) the HSPF model (http://water.usgs.gov/software/hspf.html) that was developed for simulations of hydrology and selected water quality constituents (suspended solids, phosphorus, nitrogen) in the runoff from catchment and (ii) the CE-QUAL-W2 (http://www.ce.pdx.edu/w2/) to model hydrodynamics and water quality (temperature, dissolved oxygen, algae, phosphorus, nitrogen) in longitudinal and vertical transects of stratified reservoirs. The modelling system will be calibrated, validated and then impact studies based on the results of regional climatic models will be accomplished.

The impact of climate change on hydrological-related resources of the unique environment system represented by the Black Sea coast will be investigated via an phenomenon-orientated approach. We will focus on local phenomena identified to have a major impact on regional sustainable development. Upwelling events, storm surges and spatial and temporal patterns of significant wave heights near the Romanian coast of the Black Sea will be investigated under present and future climate scenario conditions. Changes in their characteristics affect marine and terrestrial ecosystems, coastal erosion, fishery and tourism. All these phenomena imply air-sea interaction. Observational data consisting of air and sea surface temperatures, salinity and sea level from 15 hydrological and meteorological stations situated at the Romanian Black Sea coast, together with wave model results, will be used to assess the present local characteristics of air-sea interaction. Statistical models (by means of empirical orthogonal function and canonical correlation analyses) will be built to simulate the present air-sea coupling characteristics and to identify significant observational trends in meteorological and hydrological variables (air and sea surface temperature, sea level, salinity, and wave heights). In a second phase, the statistical models together with the experiment results from regional climate models will be used to assess changes in frequency occurrence and magnitude of the above-mentioned local phenomena on the western Black Sea coast under different climate conditions.
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M5.1 Month 12:
- Calibration of the models using the data over the selected period (1970-2000).
- Observed data analyses of local air-sea interaction at western Black Sea coast.
- Calibration and testing of water quality in the modelling system.
M5.2 Month 24:
- Simulation of flow in the case of modified regime.
- Evaluation of the water demand in present and future conditions.
- Regional experiment design for air-sea interaction phenomena at western Black Sea
M5.3 Month 30:
- Assessment of the vulnerability of reference basins and the adaptation measures.
- Impact study and assessments of climate change in water quality.
- Assessment of local changes in air-sea interaction modes under different climate conditions and their relevance for regional sustainable development.
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