60
tions provides a useful reminder that activities distant from a channel, but within the
drainage basin, can substantially alter river process and form. Indirect and direct
alterations are commonly interlinked, such as in scenarios where changes in upland
vegetation increase sediment yield to channels, resulting in channelization to
increase downstream conveyance (Sutter 2015). Tables 3.1 and 3.2 lists the diverse
forms of indirect and direct alteration.
3.1 Indirect Alterations of River Networks and River
Corridors
Recognition of indirect alterations of river networks and river corridors is particularly important for management of rivers as ecosystems because the effect of
these alterations is likely to be less obvious than the effect of activities
Table 3.1 Indirect alterations of river corridors and the most commonly observed, general effects
in terms of altered yields of water, sediment, nutrients, and large wood (LW) from uplands to river
corridors
Alteration
Effects on yields to river
corridors
Sample references
Climate change
Variable, but can include
altered water, sediment,
nutrients and LW
Mirza et al. (2003), Stewart et al.
(2005), Rood et al. (2008), SchmockerFackel and Naef (2010), Goode et al.
(2012) and Nilsson et al. (2015)
Change in land cover
Deforestation
Afforestation
Upland grazing
Upland cropping
Changes in fire
+ Sediment, + water, − LW
− Sediment, − water, + LW
+ Sediment, + water
+ Sediment, + water, +
nutrients
Variable, but alters water,
sediment, nutrients, and LW
Nik (1988), Luce and Black (1999) and
Fransen et al. (2001)
Keesstra et al. (2005)
Trimble and Mendel (1995)
Knox (1977) and de Boer (1997)
MacDonald et al. (2000), May and
Gresswell (2003) and Pierce et al.
(2004)
Change in
topography
Mining
Road construction
+ Sediment
+ Sediment
Rooney et al. (2012) and Wickham et
al. (2013)
Larsen and Parks (1997)
Introduced species
Variable, depending on
extent and type of species,
but include altered water,
sediment, nutrient, and LW
Baillie and Davies (2002) and Ulloa et
al. (2011)
Water diversions
between channels or
catchments
− Water yield in source
basin, + water yield in
receiving basin
Ryan (1997), Baker et al. (2011), Wohl
and Dust (2012), and Gabbud and Lane
(2015)
Urbanization
− Sediment, + water, +
nutrients
Wolman (1967), Roberts (1989) and
Bledsoe and Watson (2001)
3 Human Alterations of Rivers
tions provides a useful reminder that activities distant from a channel, but within the
drainage basin, can substantially alter river process and form. Indirect and direct
alterations are commonly interlinked, such as in scenarios where changes in upland
vegetation increase sediment yield to channels, resulting in channelization to
increase downstream conveyance (Sutter 2015). Tables 3.1 and 3.2 lists the diverse
forms of indirect and direct alteration.
3.1 Indirect Alterations of River Networks and River
Corridors
Recognition of indirect alterations of river networks and river corridors is particularly important for management of rivers as ecosystems because the effect of
these alterations is likely to be less obvious than the effect of activities
Table 3.1 Indirect alterations of river corridors and the most commonly observed, general effects
in terms of altered yields of water, sediment, nutrients, and large wood (LW) from uplands to river
corridors
Alteration
Effects on yields to river
corridors
Sample references
Climate change
Variable, but can include
altered water, sediment,
nutrients and LW
Mirza et al. (2003), Stewart et al.
(2005), Rood et al. (2008), SchmockerFackel and Naef (2010), Goode et al.
(2012) and Nilsson et al. (2015)
Change in land cover
Deforestation
Afforestation
Upland grazing
Upland cropping
Changes in fire
+ Sediment, + water, − LW
− Sediment, − water, + LW
+ Sediment, + water
+ Sediment, + water, +
nutrients
Variable, but alters water,
sediment, nutrients, and LW
Nik (1988), Luce and Black (1999) and
Fransen et al. (2001)
Keesstra et al. (2005)
Trimble and Mendel (1995)
Knox (1977) and de Boer (1997)
MacDonald et al. (2000), May and
Gresswell (2003) and Pierce et al.
(2004)
Change in
topography
Mining
Road construction
+ Sediment
+ Sediment
Rooney et al. (2012) and Wickham et
al. (2013)
Larsen and Parks (1997)
Introduced species
Variable, depending on
extent and type of species,
but include altered water,
sediment, nutrient, and LW
Baillie and Davies (2002) and Ulloa et
al. (2011)
Water diversions
between channels or
catchments
− Water yield in source
basin, + water yield in
receiving basin
Ryan (1997), Baker et al. (2011), Wohl
and Dust (2012), and Gabbud and Lane
(2015)
Urbanization
− Sediment, + water, +
nutrients
Wolman (1967), Roberts (1989) and
Bledsoe and Watson (2001)
3 Human Alterations of Rivers