42
type), patch configuration (patch arrangement in space relative to each other), patch
change (which patches change and how they change), and a shifting mosaic (patch
changes are spatially explicit and quantified) (Cadenasso et al. 2006). River scientists have devoted substantial effort to quantifying these aspects of complexity using
spatial statistics and other metrics and there are now dozens of numerical descriptors that can be applied to particular aspects of complexity in river corridors (Wohl
2016).
Fig. 2.16 Illustration of different scales of spatial heterogeneity. At the scale of river networks, the
inset map of the North St. Vrain Creek drainage in Colorado, USA (top left) has differing channel
gradients throughout the network, as indicated by different line colors in the map. At the scale of
the longitudinal profile, the photo at middle left shows a waterfall that separates longitudinal segments of differing gradient along a river in Costa Rica. At the scale of the channel planform, the
photo at bottom left shows how the Yukon River in central Alaska varies from straight to anabranching proceeding downstream (yellow arrow indicates flow direction). At the scale of valley geometry, the two photos at upper right illustrate how some reaches of North St. Vrain Creek have wide,
low gradient valleys with substantial channel-floodplain connectivity (left photo), whereas others
have steep, narrow valleys with limited lateral connectivity (right photo). At the scale of crosssectional geometry and bedforms, the photos in the middle right show a pool (top) and riffle (center) along the Rio Chagres in Panama in the left photo and a sequence of steps and pools along a
small channel in Tennessee, USA in the right photo. At the scale of channel banks and bed, the left
photo in the pair of photos at lower right illustrates sub-meter-scale undulations along the bank of
Hog Park Creek in Wyoming, USA. The right photo in the pair shows grain-size patches formed
by boulders (top) and sand and organic matter (bottom)
2 Rivers as Ecosystems
type), patch configuration (patch arrangement in space relative to each other), patch
change (which patches change and how they change), and a shifting mosaic (patch
changes are spatially explicit and quantified) (Cadenasso et al. 2006). River scientists have devoted substantial effort to quantifying these aspects of complexity using
spatial statistics and other metrics and there are now dozens of numerical descriptors that can be applied to particular aspects of complexity in river corridors (Wohl
2016).
Fig. 2.16 Illustration of different scales of spatial heterogeneity. At the scale of river networks, the
inset map of the North St. Vrain Creek drainage in Colorado, USA (top left) has differing channel
gradients throughout the network, as indicated by different line colors in the map. At the scale of
the longitudinal profile, the photo at middle left shows a waterfall that separates longitudinal segments of differing gradient along a river in Costa Rica. At the scale of the channel planform, the
photo at bottom left shows how the Yukon River in central Alaska varies from straight to anabranching proceeding downstream (yellow arrow indicates flow direction). At the scale of valley geometry, the two photos at upper right illustrate how some reaches of North St. Vrain Creek have wide,
low gradient valleys with substantial channel-floodplain connectivity (left photo), whereas others
have steep, narrow valleys with limited lateral connectivity (right photo). At the scale of crosssectional geometry and bedforms, the photos in the middle right show a pool (top) and riffle (center) along the Rio Chagres in Panama in the left photo and a sequence of steps and pools along a
small channel in Tennessee, USA in the right photo. At the scale of channel banks and bed, the left
photo in the pair of photos at lower right illustrates sub-meter-scale undulations along the bank of
Hog Park Creek in Wyoming, USA. The right photo in the pair shows grain-size patches formed
by boulders (top) and sand and organic matter (bottom)
2 Rivers as Ecosystems