Integrated River Management - River Dynamics and Integrated River Management - page 717

11 Integrated River Management
Abstract
Traditional river management has usually been specific purpose-oriented to achieve water security,
economic benefits, or habitat restoration and paid attention to only a short period, such as a few decades.
Integrated river management aims for long-term stability and sustainable development, and coordination
of various aspects of the river system, including morphology and landscape, river uses, and ecology. Four
principles for river management are proposed: (1) extending the duration of water flowing in rivers, which
may be achieved by extending the river course or reducing the flow velocity; (2) controlling various
patterns of erosion and reducing the sediment transportation in rivers; (3) increasing the diversity of
habitat and enhancing the connectivity between the river and riparian waters; and (4) restoring natural
landscapes.
The limit velocity law and equivalency principle are presented. In alluvial rivers, the average velocity
increases with an increase in discharge when the discharge is small. As the discharge exceeds the bank-full
discharge, any further increase in discharge does not result in an increase in velocity. The average
velocity approaches a limit, which is the so-called limit velocity. The limit velocity law has ecological
importance because all fish and other aquatic species cannot survive at velocities higher than the limit
velocity. Bed structures, such as step-pools system, dissipate flow energy as water flows through the
structure. Bed load motion also consumes flow energy and plays a role to protect the bed from erosion.
For mountain streams with the same stream power, strong bed structures are associated with low bed
load transportation; and weak or no bed structures are associated with intensive bed load motion.
Experiments have shown that for incised streams, the final bed profiles are the same if there is bed load
motion or there are bed structures. Bed structures and bed load motion are mutually replaceable for flow
energy consumption and streambed incision control. This is the principle of equivalency of bed load
motion and bed structures, which may be applied for river training and management.
Two methods for computing the sediment budget are proposed. One method is based on the size
distributions of sediment and sediment load in rivers, tributaries, and gullies in the sediment source area.
The core of the second method is the sediment budget matrix. Case studies of integrated river management
are presented with the Diaoga River, Wenjiagou Gully and Xiaojiang watershed as examples, in which
step-pool system were used for controlling river bed incision and debris flows and for creation of habitat
and increasing biodiversity.
Key words
Integrated river management, River morphology, Sediment budget, Bed structure, Energy dissipation,
Habitat restoration.
11.1 Principles of Integrated River Management
11.1.1 ManagementofRivers
River use has long been an important element in human activities and socioeconomic development.
Water is used for domestic, industrial, and agricultural purposes. Hydropower is exploited to power the
industry, the river channel is used for navigation, and the fresh water fishery is a traditional resource.
Moreover, rivers and the riparian areas also are used for recreation and leisure. To achieve the economic
benefits and meet other demands of humans, rivers have been dammed and channelized. The natural
fluvial processes and ecological systems within the river and riparian areas have, thus, been disturbed to