.

Чтение книги онлайн.

СКАЧАТЬ (bars, pools) Grains Large wood Sinuosity Banks Grains, Banks Bedforms (steps, pools) Grains Large wood Banks Grains Banks Boundaries (bed, banks) Grains Large wood Dominant sediment sources Fluvial Bank failure Debris flows Fluvial Bank failure Inactive channel Fluvial Bank failure Inactive channel Debris flows Fluvial Bank failure Debris flows Fluvial, Hillslope Debris flows Fluvial Hillslope Debris flows Fluvial Hillslope Debris flows Hillslope Debris flows Sediment storage elements Overbank bedforms Overbank bedforms inactive channel Overbank bedforms inactive channel Overbank inactive channel Bedforms Lee and stoss sides of obstructions Bed Typical slope <0.03 <0.001 0.001> <0.02 0.001> <0.03 0.03> <0.08 0.08> <0.3 Variable >0.2 Typical confinement Unconfined Unconfined Unconfined Variable Confined Confined Confined Confined Pool spacing (channel widths) Variable 5–7 5–7 none 1–4 <1 Variable Variable

Table 2.2 Additional river types to those listed in Table 2.1, with channel slope as a discriminator.

Reference	Pool	Glide	Riffle	Rapid	Cascade
Bisson et al. (1988)			S < 0.04	S > 0.04	S > 0.04 S < 0.16
Sullivan (1986)	S < 0.01	S > 0.01 S < 0.02	S > 0.01 S < 0.04	S > 0.04	S ~ 0.068
Grant et al. (1990)	S ~ 0.005	S < 0.02	S ~ 0.011	S ~ 0.029	S ~ 0.055
Wood‐Smith and Buffington (1996)	Closed topographic depression		S > 0.02 S < 0.04		S > 0.04
Montgomery and Buffington (1997)	S ~ 0.012	S > 0.0015 S < 0.04		S > 0.02 S < 0.076	S ~ 0.11

Figure 2.3 The River Styles typology

      (Source: Based on Brierley and Fryirs (2005). © John Wiley & Sons).

      2.3.3 River Styles Framework

The River Styles framework (Brierley and Fryirs 2005) develops a more holistic view of fluvial systems, providing a geomorphic template upon which biophysical processes are assessed within a catchment context. The River Styles methodology reflects both river character and behaviour. As such the framework also provides a basis for assessing geomorphic river condition and recovery potential, framed in terms of evolutionary pathways for each channel type. The River Styles typology is summarised in Figure 2.3.

      2.3.4 Extended River Typology

The Extended River Typology developed by Rinaldi et al. (2015) identified 22 morphological types (Figure 2.4) classified by confinement (confined, partly confined, and unconfined), dominant bed material calibre (bedrock, boulder, cobble, gravel, sand, and silt), and planform (straight‐sinuous, meandering, pseudo‐meandering, wandering, braided, island‐braided, and anabranching).

      2.3.5 Scottish Environment Protection Agency (SEPA) Classification

As mentioned above, SEPA (2012) proposed a river classification system for Scottish rivers based on and developing the Montgomery and Buffington (1997) typology. Twelve channel systems have been distinguished by SEPA, and these have been amalgamated into six functional channel types distinguished based on their geology (bedrock or alluvial), slope, and gross sinuosity (Table 2.3). The SEPA hierarchical classification provides a useful summary of the character of each river type proposed (Table 2.4).

Figure 2.4 The Extended River typology

      (Source: Modified from Rinaldi et al. (2015). © John Wiley & Sons).

2.4 River Classification Framework Used in This Book

It is clear from the short review above that there is little consensus regarding a robust typology for fluvial systems. This situation СКАЧАТЬ