European flooding. However, different hydrologic
responses to precipitation changes have been identified
in China, where altered precipitation changes are mirrored
by shortening consecutive precipitation episodes and
shifts of seasonal precipitation changes (Zhang et al.,
2011a). Uneven spatiotemporal distribution of precipitation changes and also different hydrologic responses to
climate change in different regions of the globe result in
different types of variability and availability of water
resources over the earth.
Flood and drought hazards may be the most serious
natural disasters impacting human society. Economic
losses due to floods and droughts have been increasing
with population growth and development and associated
poor land use in the floodplains of great rivers
(Changnon, 1985). A flood is an overflow of water that
inundates land areas, and a flood disaster refers to
a flood event that causes socioeconomic loss or mortality.
Droughts are long-term phenomena affecting large
regions inflicting significant damages on both human
lives and socioeconomic conditions. A drought event is
a period characterized by insufficient precipitation, soil
moisture, and water resources for supporting the socioeconomic activities of a region. However, there is not
a universal definition of drought due to the wide variety
of sectors affected by a drought, its diverse geographical
and temporal distribution, and the demand placed on
water supply by human-use systems. The most wellknown and widely used classification of droughts is the
classification initially proposed by Dracup et al. (1980)
and subsequently integrated by Wilhite and Glantz
(1985). The American Meteorological Society (2004)
adopted this drought classification system. Based on the
nature of the water deficit, four types of droughts are
defined: (1) meteorological drought, (2) hydrologic
drought, (3) agricultural drought, and (4) socioeconomic
drought. This work focuses on meteorological drought
which is defined as a deficit of precipitation over
a region within a certain time interval.
Water resource management
Water resource management focuses on planning, allocating, developing, distributing, and managing the optimum
use of water resources, and the final objective is to make
good use of limited water resources and to optimally
satisfy water demands of various sectors. Climate change
is expected to alter the spatiotemporal distribution of precipitation and evapotranspiration patterns (Tsanis et al.,
2011). These alterations, in turn, cause variability in the
availability of water resources, river discharge, and
seasonal water supply (Arnell et al., 2011; Koutroulis
et al., 2013). The demand for freshwater is rising, but
a variety of factors, including population growth, water
pollution, economic progress, land use change, and
climate change, render its availability uncertain in the
future (Davies and Simonovic, 2011). Awareness of
greater water shortages has aroused an increasing interest
in the planning of water resources (Alcamo et al., 2003),
with the aim to develop and implement appropriate water
resource infrastructure and management strategies
(Davies and Simonovic, 2011).
Global warming, as a result of human-induced emission
of greenhouse gases, has the potential to significantly
affect the hydrologic cycle (IPCC, 2007), which is intensifying with the extra precipitation being unequally distributed around the globe (Arnell, 1999). Uneven spatial
distribution of precipitation and major shifts in the timing
of wet and dry seasons further enhance the uncertainty of
water supply and the magnitude of water shortages in both
space and time. Water resources are vital for the environment, economy, and society. Therefore, changes in the
water resource base have the potential to significantly
impact environmental quality, economic development,
and social welfare. How to allocate, use, and save water
resources for sustainable development of human society
and conservation of the environment is a critical element
which human beings are facing in the changing
environment.
In
1997,
the
United
Nations
published
a Comprehensive Review of the Freshwater Resources
of the World (WMO, 1997). The assessment included four
components: (1) the collation of up-to-date national-level
data on water resources and their use, (2) the development
of projections of future use (to 2025 and 2050), (3) the
description of present and future pressures, and (4) the
assessment of strategies and options for the sustainable
development of world water resources. It highlighted the
effects of increasing population and economic development on water resource availability. It also estimated that
approximately one-third of the world’s population currently lives in countries experiencing moderate to high
water stress and predicted that by 2025 as much as
two-thirds of the larger world population could be under
stress conditions simply due to the increase in population
and water use. Arnell (1999) investigated the effects of climate change on water resources globally, noting that the
average annual runoff will increase in high latitudes, in
equatorial Africa and Asia, and Southeast Asia, but will
decrease in midlatitudes and most subtropical regions. In
addition, the rise in temperature associated with climate
change will lead to a general reduction in the proportion
of precipitation falling as snow and a consequent reduction in many areas in the duration of snow cover. This
has implications for the timing of streamflow in such
regions with a shift from spring snow melt to winter
runoff.
Summary
Water resources are the key to the water security, the
food security, and hence the sustainable development
732
WATER RESOURCES AND CLIMATE CHANGE
responses to precipitation changes have been identified
in China, where altered precipitation changes are mirrored
by shortening consecutive precipitation episodes and
shifts of seasonal precipitation changes (Zhang et al.,
2011a). Uneven spatiotemporal distribution of precipitation changes and also different hydrologic responses to
climate change in different regions of the globe result in
different types of variability and availability of water
resources over the earth.
Flood and drought hazards may be the most serious
natural disasters impacting human society. Economic
losses due to floods and droughts have been increasing
with population growth and development and associated
poor land use in the floodplains of great rivers
(Changnon, 1985). A flood is an overflow of water that
inundates land areas, and a flood disaster refers to
a flood event that causes socioeconomic loss or mortality.
Droughts are long-term phenomena affecting large
regions inflicting significant damages on both human
lives and socioeconomic conditions. A drought event is
a period characterized by insufficient precipitation, soil
moisture, and water resources for supporting the socioeconomic activities of a region. However, there is not
a universal definition of drought due to the wide variety
of sectors affected by a drought, its diverse geographical
and temporal distribution, and the demand placed on
water supply by human-use systems. The most wellknown and widely used classification of droughts is the
classification initially proposed by Dracup et al. (1980)
and subsequently integrated by Wilhite and Glantz
(1985). The American Meteorological Society (2004)
adopted this drought classification system. Based on the
nature of the water deficit, four types of droughts are
defined: (1) meteorological drought, (2) hydrologic
drought, (3) agricultural drought, and (4) socioeconomic
drought. This work focuses on meteorological drought
which is defined as a deficit of precipitation over
a region within a certain time interval.
Water resource management
Water resource management focuses on planning, allocating, developing, distributing, and managing the optimum
use of water resources, and the final objective is to make
good use of limited water resources and to optimally
satisfy water demands of various sectors. Climate change
is expected to alter the spatiotemporal distribution of precipitation and evapotranspiration patterns (Tsanis et al.,
2011). These alterations, in turn, cause variability in the
availability of water resources, river discharge, and
seasonal water supply (Arnell et al., 2011; Koutroulis
et al., 2013). The demand for freshwater is rising, but
a variety of factors, including population growth, water
pollution, economic progress, land use change, and
climate change, render its availability uncertain in the
future (Davies and Simonovic, 2011). Awareness of
greater water shortages has aroused an increasing interest
in the planning of water resources (Alcamo et al., 2003),
with the aim to develop and implement appropriate water
resource infrastructure and management strategies
(Davies and Simonovic, 2011).
Global warming, as a result of human-induced emission
of greenhouse gases, has the potential to significantly
affect the hydrologic cycle (IPCC, 2007), which is intensifying with the extra precipitation being unequally distributed around the globe (Arnell, 1999). Uneven spatial
distribution of precipitation and major shifts in the timing
of wet and dry seasons further enhance the uncertainty of
water supply and the magnitude of water shortages in both
space and time. Water resources are vital for the environment, economy, and society. Therefore, changes in the
water resource base have the potential to significantly
impact environmental quality, economic development,
and social welfare. How to allocate, use, and save water
resources for sustainable development of human society
and conservation of the environment is a critical element
which human beings are facing in the changing
environment.
In
1997,
the
United
Nations
published
a Comprehensive Review of the Freshwater Resources
of the World (WMO, 1997). The assessment included four
components: (1) the collation of up-to-date national-level
data on water resources and their use, (2) the development
of projections of future use (to 2025 and 2050), (3) the
description of present and future pressures, and (4) the
assessment of strategies and options for the sustainable
development of world water resources. It highlighted the
effects of increasing population and economic development on water resource availability. It also estimated that
approximately one-third of the world’s population currently lives in countries experiencing moderate to high
water stress and predicted that by 2025 as much as
two-thirds of the larger world population could be under
stress conditions simply due to the increase in population
and water use. Arnell (1999) investigated the effects of climate change on water resources globally, noting that the
average annual runoff will increase in high latitudes, in
equatorial Africa and Asia, and Southeast Asia, but will
decrease in midlatitudes and most subtropical regions. In
addition, the rise in temperature associated with climate
change will lead to a general reduction in the proportion
of precipitation falling as snow and a consequent reduction in many areas in the duration of snow cover. This
has implications for the timing of streamflow in such
regions with a shift from spring snow melt to winter
runoff.
Summary
Water resources are the key to the water security, the
food security, and hence the sustainable development
732
WATER RESOURCES AND CLIMATE CHANGE