conflicts of interests (e.g. agriculture) between stakeholders, water management
measures are implemented since many years. Such measures mainly focus on
the regulation of water levels in lakes, rivers and groundwater through the construction of slices, locks, drainage channels or artificial reservoirs, with high
impacts to the local biodiversity. To preserve a favourable conservation status
under changing climatic conditions park managers require information about
potential impacts of climate change in their area. Climate change projections
from regional climate models can provide such information, even though with
a low spatial resolution (several km
2 ) concerning biodiversity. Hydrological
models can downscale these information and investigate potential impacts of
climate change or management measures to the local water regime like river runoff,
lake levels or water availability in an area. The projected changes due to climate
change vary significantly across Central and Eastern Europe. Hence, the following
chapter provides an overview of how climate change affects the hydrological
regimes in Central and Eastern Europe. It focuses on the underlying processes
and which general hydrological impacts can be expected in the light of climate
change. First of all, major processes of the water cycle on river catchment scale
are explained. Furthermore, changes of the most important water cycle processes
due to climate change, precipitation and evapotranspiration, as well as climatically
indicator for the potential water availability the climatic water balance are
summarised. This leads to the impacts on river flow regimes and changes the
inter- and intra-annual variability, which are described in the following
sub-section. The subsequent chapter shows the role of water resources management
on stream flow and its availability to counterbalance effects of climate change.
Finally, climate change impacts on the glaciers in the European Alps as important
storage component are illustrated.
3.2 Overview About the Hydrological Cycle
The hydrological cycle describes the continuous circulation of water between
ocean, atmosphere and land. Water is transferred through physical processes like
evapotranspiration, precipitation, infiltration and river runoff. This circle from one
reservoir to another involves energy exchange in terms of heat transfer, solar
radiation and gravitational potential energy. During these processes water can
change its aggregation state (liquid, vapour, or ice) various times. Hydrological
processes encompass a variety of spatial and temporal scales. At the river catchment scale, the hydrological cycle comprises precipitation as major input, various
transfer processes, different storages and outputs. They are referred to by hydrologists as components of the water balance.
Precipitation is condensed water vapour and mostly occurs as rain, but also
includes snow, hail, drizzle, sleet and fog drip. Snow can accumulate and eventually
32
J. Stagl et al.
measures are implemented since many years. Such measures mainly focus on
the regulation of water levels in lakes, rivers and groundwater through the construction of slices, locks, drainage channels or artificial reservoirs, with high
impacts to the local biodiversity. To preserve a favourable conservation status
under changing climatic conditions park managers require information about
potential impacts of climate change in their area. Climate change projections
from regional climate models can provide such information, even though with
a low spatial resolution (several km
2 ) concerning biodiversity. Hydrological
models can downscale these information and investigate potential impacts of
climate change or management measures to the local water regime like river runoff,
lake levels or water availability in an area. The projected changes due to climate
change vary significantly across Central and Eastern Europe. Hence, the following
chapter provides an overview of how climate change affects the hydrological
regimes in Central and Eastern Europe. It focuses on the underlying processes
and which general hydrological impacts can be expected in the light of climate
change. First of all, major processes of the water cycle on river catchment scale
are explained. Furthermore, changes of the most important water cycle processes
due to climate change, precipitation and evapotranspiration, as well as climatically
indicator for the potential water availability the climatic water balance are
summarised. This leads to the impacts on river flow regimes and changes the
inter- and intra-annual variability, which are described in the following
sub-section. The subsequent chapter shows the role of water resources management
on stream flow and its availability to counterbalance effects of climate change.
Finally, climate change impacts on the glaciers in the European Alps as important
storage component are illustrated.
3.2 Overview About the Hydrological Cycle
The hydrological cycle describes the continuous circulation of water between
ocean, atmosphere and land. Water is transferred through physical processes like
evapotranspiration, precipitation, infiltration and river runoff. This circle from one
reservoir to another involves energy exchange in terms of heat transfer, solar
radiation and gravitational potential energy. During these processes water can
change its aggregation state (liquid, vapour, or ice) various times. Hydrological
processes encompass a variety of spatial and temporal scales. At the river catchment scale, the hydrological cycle comprises precipitation as major input, various
transfer processes, different storages and outputs. They are referred to by hydrologists as components of the water balance.
Precipitation is condensed water vapour and mostly occurs as rain, but also
includes snow, hail, drizzle, sleet and fog drip. Snow can accumulate and eventually
32
J. Stagl et al.