26 / 40
26
Intensified land use impacts water resources
Intensified land use associated with exploitation, im-
migration, population growth and resettlement along
road corridors has major impacts on the water resources
and their biodiversity (Dudgeon, 1992; 1995; 2000;
Malmqvist and Rundle, 2002; Dudgeon, 2002). The
processes are however very variable.
Overexploitation of limited water resources is a grow-
ing problem that is not easily solved in interior Asia. If
climate change will result in less precipitation as snow
or glacial recession, the impacts both on wildlife and
human populations may become disastrous. Indeed, as
more people have settled in areas prone to desertification
even with natural cycles of expansion and contraction of
the Taklamakan and Gobi deserts, the result is none the
less critical for these people. However, also here human
land use seems to play a primary role in aggravating the
impacts of such cycles on both people and biodiversity
(Liu and Sun, 2002; Lu et al., 2003)). Dust storms and
blown sand represent an increasing problem for com-
munication, health and transport in the region (Sun et
al., 2000; Xuan and Sokolik, 2002).
Vegetated hills, slopes, wetlands and forests are vital
catchments for most rivers, and help purify water and
reduce silt content in rivers by natural protection from
erosion. With intensified land use along road corridors,
forests are cut for firewood or intensified grazing results
in overgrazing, deforestation and subsequent increase
in erosion, flashfloods and land slides particularly along
road corridors (Dudgeon, 1992; 1995; Zong and Chen,
2000; Du et al., 2001). This is particularly true also for
abandoned agricultural terraces that are extremely sus-
ceptible to erosion unlike well-managed terraces. This
leads to increased waste and run-off into drainages and
major rivers, including reduced capacity of watersheds
to manage monsoon floods (Dudgeon, 1992; 1995; Col-
lins and Jenkins, 1996; Zong and Chen, 2000; Du et
al., 2001). The silt content increase and water quality
becomes seriously reduced.
Infrastructure development also facilitates increased im-
migration. Growing land and population pressures lead
to increasing settlement in flood-risk areas along lakes,
behind former flood dikes, in drained wetlands and
partly on steep slopes subject to land slides and erosion.
Hence, when upland ability to retain floods is reduced
and people simultaneously settle in flood prone areas,
the human and environmental impacts of severe or even
natural fluctuations in floods become serious. This is
well known from the flooding of the Yangtze river which
in part was attributed to deforestation and settlement
patterns (Dudgeon, 1995; Zong and Chen, 2000; Du
et al., 2001; Lu et al., 2003). China has invested large
and also successful efforts in reducing deforestation in
some of the catchments. Yet, as land use still intensifies
in many regions, the high silt content resulting from
erosion and the increasing water consumption for ir-
rigation still remains a growing threat that will require
further attention.