Geography Reference
In-Depth Information
Figure 3.10. Land cover information from satellite data. http://www.nasa.gov/images/content/121557main_landCover.jpg .
( 2009 ). For many cases, not only information on the top-
soil (say the upper metre) may be relevant, as is provided
by FAO and HWSD, but also data of deeper aquifers and
groundwater systems. The Worldwide Hydrogeological
Mapping and Assessment Project (WHYMAP), provides
such maps by combining various national, regional and
global sources.
In a very few cases, extra effort has been made to create
a hydrologically focused soil classification. UK soils have
been delineated according to their hydrological properties
to produce the 29-class Hydrology Of Soil Types (HOST)
classification ( Figure 3.11 ). The HOST classification is
based on a number of conceptual models that describe
dominant pathways of water movement through the soil
and, where appropriate, substrate. The HOST data set is
available at a 1 km grid that records, for each grid square,
the percentage of the 1 km × 1 km area given to each
HOST class present (Boorman et al., 1995 ). Efforts have
been made to expand such hydrologically relevant catch-
ment characteristics across Europe (Schneider et al., 2007 ).
and deforestation, abstractions for irrigation and energy
production, and consumptive water use. Related to these
activities are increasing emissions of greenhouse gases that
alter our climate, as well as water resources infrastructure
that changes flow paths and storage behaviour of river
basins. For example, during the last century, irrigable land
increased from 40 million hectares (Mha) to 215 Mha
(Freydank and Siebert, 2008 ). About 40% of the current
irrigable land is supplied with surface water that is
impounded by large artificial reservoirs and dams built
on rivers (Lempérière, 2006 ). Figure 3.12 provides illus-
trative examples of anthropogenic effects on runoff due to
hydropower generation and irrigation abstractions. At
larger spatial scales, land use changes can be observed
using remotely sensed information as discussed above.
However, the historical extent of this information is rather
short, and other, much more time consuming approaches,
are needed to create a historical timeline.
Dams are constructed for different purposes: diversion,
irrigation, flood protection, hydropower, water supply,
recreation, navigation etc. The world has approximately
845 000 dams (Jacquot, 2009 ), although an exact number
is not known. About 50 000 of these are classified as
'
3.6 Data on anthropogenic effects
Human activities have a significant impact on the terres-
trial water cycle (Braden et al., 2009 ), but quantifying their
impact is often difficult (Wagener et al., 2010 ). Major
activities include land cover changes such as urbanisation
(i.e., over 15 m high) by the International Com-
mission on Large Dams (ICOLD, 2009 ). The water
impounded in these large dams amounts to about 10%
of the annual river runoff and covers one-third that of the
large
'
Search WWH ::




Custom Search