5 Climate Change Impact on Hydrological Regimes …
123
nature and effects of climate variability and potential effects climate change. Lack of
locally relevant data constrains the development of adaptation measures appropriate
for different environmental settings and communities. This often leads to the recommendation of measures based on “one-size fits all”. The limited financial resources
are invested in ineffective adaptations measures.
6.4 Hydrological Regimes
Due to the altered rainfall patterns (increase in flooding and droughts in addition to
increased variability and changes in rainfall characteristics) flow regimes of rivers are
likely to change. For example, dry season flows are likely to be reduced significantly
during dry seasons, that which will not only affect irrigation but also hydro electricity
generation. Ecologically, several observations can be made from this of which the
following are key: Firstly, river flows are a major determinant of physical habitat
in streams, which in turn is a major determinant of biotic composition; Secondly,
aquatic species have evolved life history strategies primarily in direct response to
the natural flow regimes; Thirdly, maintenance of natural patterns of longitudinal
and lateral connectivity is essential to the viability of populations of many riverine
species; Finally, the invasion and success of exotic and introduced species in rivers is
facilitated by the alteration of flow regimes. Thus the impacts of flow change (naturally or due to climate change) are manifest across broad taxonomic groups including
riverine plants, invertebrates and fish. However, despite growing recognition of these
relationships, there is still dearth in literature for Southern Africa on prediction and
quantification of biotic responses to altered flow regimes. One obvious difficulty is
the ability to distinguish the direct effects of modified flow regimes from impacts
associated with land use change and climate change that often accompanies water
resource development.
7 Conclusion
From this discussion, a picture of the availability of the water resources in the future
can be constructed and the implications of these findings are as follows: (1) Water
availability is likely to be compromised, since, for example, rainfall for a season may
now fall within a few days. Thus altered rainfall characteristics (intensity, duration,
etc…) will eventually impact on flow regimes, hence available water resources—
spatially and temporally. (2) Water management measures are likely to become strict,
since water shortages as experienced in Cape Town, South Africa from 2017 to 2018,
are a certain possibility. Hence management of water resources, i.e. implementation
of Integrated Water Resources Management Systems have to be expedited. (3) Most
of the population in southern Africa depends on rain-fed agriculture and most of
this population lives in rural areas where mean annual rainfall is approximately
123
nature and effects of climate variability and potential effects climate change. Lack of
locally relevant data constrains the development of adaptation measures appropriate
for different environmental settings and communities. This often leads to the recommendation of measures based on “one-size fits all”. The limited financial resources
are invested in ineffective adaptations measures.
6.4 Hydrological Regimes
Due to the altered rainfall patterns (increase in flooding and droughts in addition to
increased variability and changes in rainfall characteristics) flow regimes of rivers are
likely to change. For example, dry season flows are likely to be reduced significantly
during dry seasons, that which will not only affect irrigation but also hydro electricity
generation. Ecologically, several observations can be made from this of which the
following are key: Firstly, river flows are a major determinant of physical habitat
in streams, which in turn is a major determinant of biotic composition; Secondly,
aquatic species have evolved life history strategies primarily in direct response to
the natural flow regimes; Thirdly, maintenance of natural patterns of longitudinal
and lateral connectivity is essential to the viability of populations of many riverine
species; Finally, the invasion and success of exotic and introduced species in rivers is
facilitated by the alteration of flow regimes. Thus the impacts of flow change (naturally or due to climate change) are manifest across broad taxonomic groups including
riverine plants, invertebrates and fish. However, despite growing recognition of these
relationships, there is still dearth in literature for Southern Africa on prediction and
quantification of biotic responses to altered flow regimes. One obvious difficulty is
the ability to distinguish the direct effects of modified flow regimes from impacts
associated with land use change and climate change that often accompanies water
resource development.
7 Conclusion
From this discussion, a picture of the availability of the water resources in the future
can be constructed and the implications of these findings are as follows: (1) Water
availability is likely to be compromised, since, for example, rainfall for a season may
now fall within a few days. Thus altered rainfall characteristics (intensity, duration,
etc…) will eventually impact on flow regimes, hence available water resources—
spatially and temporally. (2) Water management measures are likely to become strict,
since water shortages as experienced in Cape Town, South Africa from 2017 to 2018,
are a certain possibility. Hence management of water resources, i.e. implementation
of Integrated Water Resources Management Systems have to be expedited. (3) Most
of the population in southern Africa depends on rain-fed agriculture and most of
this population lives in rural areas where mean annual rainfall is approximately