Integrated River Management - River Dynamics and Integrated River Management - page 718

a great extent. River regulation and river training have been performed for various purposes and negative
effects have been shown in numerous cases. In some cases the negative effects are so serious that humans
have to consider renaturalizing the regulated rivers. Only by using the strategies of integrated river
management the diverse river uses and natural fluvial processes and ecological systems may be
harmonized.
Until approximately 1750, the scale of river regulation worldwide was small, and engineering works
modified or affected the natural dynamics of rivers. Subsequently, beginning in Europe, major schemes
sought complete control of rivers from the headwaters to the mouth. In North America, Ellett proposed
the control of the Ohio and Lower Mississippi Rivers by using both headwater storage reservoirs and
channelization of the lower river ( Gore and Petts, 1989 ). Complete control of rivers has been achieved during
the 20th century with the development of dam-building technology and construction of numerous dams
on rivers.
The reservoir index, RI , is defined as

RI total capacity of reservoirs/annual runoff (11.1)

Rivers can be grouped according to the degree of regulation by humans:
(1) Natural river, RI < 10%;
(2) Half-natural river, 10%< RI <50%;
(3) Half-controlled river, 50%< RI <100%;
(4) Controlled river, RI > 100%.
Figure 11.1 shows the RI and the total capacity of reservoirs on several rivers. The Yellow, Mississippi,
Colorado, and Nile rivers have become human-controlled rivers and the Yangtze and Pearl rivers are
half-natural rivers.

Fig. 11.1 Total storage capacity and reservoir index for several major rivers

Except for damming, channel alignment and levee construction are the most commonly practiced river
training methods. The main aims of these methods are to control flood and enhance sediment-transport
capacity. The fluvial processes are changed by these methods and most of the effects are obviously
intentional, since natural rivers do not offer sufficient flood protection.
In river management projects factors including sediment transportation, fluvial processes, ecology
protection and fish migration have been taken into consideration. Integrated river management comprises:
(1) taking the watershed, including the tributaries, middle reaches, lower reaches, and the estuary as an
integrated entity in planning, design, and management; (2) mitigating or controlling the negative impacts
on hydrology, erosion and sedimentation, fluvial processes, land use, and environment while in achieving
economic benefit, from water resources development, flood safety management, and hydropower