Evangelos A. Baltas

Climate Change Impacts on the Water Supply of Thessaloniki

This paper examines the assessment of the impacts of climate change on water resources in the Aliakmon river basin, Northern Greece, and on some critical water management issues, such as reservoir storage and water supply of the city of Thessaloniki. A monthly conceptual water balance model was calibrated using historical hydrometeorological data. This model was applied to estimate runoffs in the entrance of the Polyfyto reservoir under two different equilibrium scenarios (UKHI, CCC) referring to 2050. Reduction of the mean annual runoff, mean winter runoff and summer runoff would occur. By using these scenarios, the sensitivity of the risk associated with the water supply for the city of Thessaloniki was evaluated under conditions of altered runoff. Increases of the risks associated with the annual quantities of water supply were observed, particularly under the UKHI scenario.

Impact of Climate Change on the Hydrological Regime and Water Resources in the Basin of Siatista

This paper examines an assessment of the impact of climate change on hydrological regimes and water resources in the basin of Siatista, a sub-basin of the Aliakmon river basin, located in Northern Greece. Initially all acquired hydrometeorological data of the study area, as well as the hydrometric data at the outlet of the basin, were analyzed and processed. A monthly conceptual water balance model was then calibrated using historical hydrometeorological data for determining changes in streamflow runoff under two different equilibrium scenarios (UKHI, CCC) referring to the years 2020, 2050 and 2100. It was found that by applying the two scenarios there will be a reduction of the mean winter runoff values, a serious reduction of summer runoff, an increase of maximum annual runoff and a decrease of minimum annual runoff values, an increase of potential and actual evapotranspiration, leading to a decrease of soil moisture, a reduction of snow accumulation and melting due to temperature increases, resulting in a decrease of spring runoff values and a shifting of the wet period towards December, resulting in severe prolongation of the dry period.

Climatic Conditions and Availability of Water Resources in Greece

Greece is characterized by a special geomorphologic structure, the result of which is a variety of climatic conditions and the division of the area into a plethora of basins and a number of water districts. This study aims to analyze the climatic conditions, as well as of the availability of water resources across the country. The air temperature and rainfall data of the time period 1965–95 were acquired from 40 meteorological stations and processed on a monthly and annual basis. The spatial distribution of the aforementioned climatic variables, as well as of the climatic indices of Johansson Continentality and De Martonne Aridity was derived. The results show that the Pindos mountain range is a major contributing factor in the climatic variety, dividing the country into windward, high precipitation western areas and leeward, low precipitation eastern areas. This precipitation pattern affects directly the availability of water resources, which was briefly analyzed in each water district.

GIS-based optimisation of the hydrometeorological network in Greece

Abstract The operation of a network of hydrometeorological stations constitutes basic infrastructure for the management of water resources. Despite the increased need for rational water management in Greece, there is not a single network of hydrometeorological stations. Various State Services have established sectional networks of limited coverage, resulting in many disadvantages. This study aims at the optimisation of the existing network, using GIS methods. An optimum network of hydrometeorological stations is designed, which constitutes the base for the optimisation of the present network. The optimum network consists of 1379 hydrometeorological stations and is based on the guidelines of international organisations. The uniform spatial distribution of the stations and criteria concerning the selection of the appropriate site, such as the low terrain slope, easy accessibility and proximity to special interest points, were of special importance for its development. Eventually, only the 20% of the existing stations remain at their locations and are included in the optimised network. The rest of the stations should be redistributed according to the proposed sites of the optimum network.

Climate Change and Associated Implications for the Water Policy Framework in the Basin of Venetikos

The impact of climate change on the hydrological regime and water resources in the basin of Venetikos has been assessed in this paper. Venetikos is a sub-basin of the Aliakmon River Basin, located in northern Greece. A monthly conceptual water balance model was calibrated using historical hydrometeorological data to determine changes in stream-flow runoff under two different equilibrium scenarios (UKHI, CCC) for year 2020, 2050 and 2100. The application of the two scenarios resulted in reduction of the mean winter and summer runoff values, and increase in maximum annual and decrease in minimum annual runoff values. Additionally, an increase of potential and actual evapo-transpiration was noticed due to temperature increase. As a result, a reduction of snow accumulation, as well as a decrease in spring runoff values and soil moisture are expected. A shift of the wet period towards December is remarked, resulting in severe prolongation of the dry period. Consequently, the water policy should be revised in order to address the above possible future changes.

Hydrological response and examination of the water resources in an experimental watershed in Greece

The present study examines the impact of an altered rainfall regime on surface and groundwater resources at a gauged mountainous experimental watershed located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece. The study period concerns the hydrological years from October 2003 to September 2008. A decrease in the annual rainfall depth in the first years and in particular the distinct decrease in winter rainfall has led to a reduction in runoff and groundwater reserves. The authors recommend an infrastructure-based management programme to ensure the sustainable use of the diminishing water resources.

Measures against climate change and its impacts on water resources in Greece

This paper examines the actions toward the reduction of greenhouse gas emissions to the atmosphere that Greece has implemented to comply with international conventions and the Kyoto Protocol. It also concerns the analysis and processing of climate variables and the assessment of the impact of climate change on water resources in Northern Greece and on some critical water management issues, such as reservoir storage and water supply for agriculture and domestic use. Initially, a monthly conceptual water balance model was applied to estimate runoff values in the entrance of the Polyfyto reservoir under the UKHI equilibrium scenario referring to the year 2100. It was found that the mean annual runoff, mean winter runoff and summer runoff values will be reduced. Increases of the risks associated with the annual quantities of water supply have been observed.

Hydrological balance and application of the MedWater Model on Naxos Island

The MedWater model was used to determine both the present and future water balances of the largest water basin on Naxos Island, Greece, comparing water resource availability with water demand while also testing assumptions related to the regional hydrological context and different future scenarios. The model indicated that: the required quantities of water for both irrigation and drinking needs reach their annual maximum values during the summer season; the annual water balance shows a general surplus, but not on a monthly basis; the available quantities of water are not enough to cover irrigation demands during the annual dry period; available water resources maximize in March and are generally under-exploited; and the required volumes of water for both irrigation and direct human consumption will increase in the future.

Flash flood forecasting using weather radar

A hydrometeorolo gical study in a Pinios river suhhasin was conducted to demonstrate the use of a WSR-74 S-hand weather radar and raingage data for flash flood forecasting. A series of storm events recorded every 20 to 30 minutes were analysed and processed. Two different approaches were employed for the adjustment of the radar rainfall field. A rainfall-runoff model based on the unit hydrogiaph theory was applied by using as rainfall input ramgage and radar rainfall information. It was found that the model performs better using weather radar combined with ramgages than ramgages alone.