River corridor enhancement, rehabilitation, and restoration is a concept that involves different activities with a degraded river or stream in order to return it to its natural condition. In practice, restoring a river or stream to its original state is almost impossible. However, some limited enhancement works can be done to restore the river corridors.

The general environment of the riparian zone and the ecological role of the riparian vegetation must be taken into account in interventions on fluvial systems. In addition to its ecological function for aquatic habitats and terrestrial wildlife, this vegetation provides important socioeconomic benefits (e.g., flood defense, scenic and aesthetic quality, and leisure) as well as regulation of ecosystems (e.g., riverbed stability, erosion control, filtering/retention of sediments, flood defense, wastewater treatment, and pesticide control).

Ecologically oriented interventions in the riparian vegetation should consider the following criteria:

• keeping a structure of vegetation of different ages that allows the presence of both shrub and tree layers
• periodic cutting and selective thinning of adult trees that present problems of stability, and elimination of invading species in favor of autochthonous species and, possibly, valued species
• keeping shrubby vegetation where possible, since it can bend easily during floods and does not obstruct bridge sections (Colombo et al. 2002)

The influence of periodical flooding processes, sedimentation, and erosion can be felt in the transition areas of riparian vegetation. Structural measures to regulate the river, such as large hydraulic infrastructures that aim to improve water flow conditions, usually cause environmental changes throughout the fluvial ecosystem. These can be reflected in the destruction of habitats and vegetation, alteration of physico-chemical water characteristics, and other modifications at the level of the whole ecosystem. The overall interventions on river corridors should focus on maintenance, rehabilitation, and restoration of well-structured corridors consisting of wide lateral strips containing varied topographical elements and populated by autochthonous grass, shrub, and tree species.

For rehabilitation to be successful, proper planning and interaction with stakeholders must complement the
ecosystem perspective listed above. Socioeconomic considerations will play a large role in determining where and
when different rehabilitation measures are applied. (WMO 2006a)

The table below summarizes some of the main measures used to enhance, rehabilitate, and restore river corridors. The most common efforts focus on enhancing riparian zones by planting grasses, bushes, and trees; stream bank stabilization; the removal of dams and other man-made structures; and stocking the river with fish or other living organisms.

Measures to enhance, rehabilitate and restore river corridors:

River corridor enhancement, rehabilitation, and restoration is a concept that involves different activities with a degraded river or stream in order to return it to its natural condition. In practice, restoring a river or stream to its original state is almost impossible. However, some limited enhancement works can be done to restore the river corridors.

The general environment of the riparian zone and the ecological role of the riparian vegetation must be taken into account in interventions on fluvial systems. In addition to its ecological function for aquatic habitats and terrestrial wildlife, this vegetation provides important socioeconomic benefits (e.g., flood defense, scenic and aesthetic quality, and leisure) as well as regulation of ecosystems (e.g., riverbed stability, erosion control, filtering/retention of sediments, flood defense, wastewater treatment, and pesticide control).

Ecologically oriented interventions in the riparian vegetation should consider the following criteria:

• keeping a structure of vegetation of different ages that allows the presence of both shrub and tree layers
• periodic cutting and selective thinning of adult trees that present problems of stability, and elimination of invading species in favor of autochthonous species and, possibly, valued species
• keeping shrubby vegetation where possible, since it can bend easily during floods and does not obstruct bridge sections (Colombo et al. 2002)

The influence of periodical flooding processes, sedimentation, and erosion can be felt in the transition areas of riparian vegetation. Structural measures to regulate the river, such as large hydraulic infrastructures that aim to improve water flow conditions, usually cause environmental changes throughout the fluvial ecosystem. These can be reflected in the destruction of habitats and vegetation, alteration of physico-chemical water characteristics, and other modifications at the level of the whole ecosystem. The overall interventions on river corridors should focus on maintenance, rehabilitation, and restoration of well-structured corridors consisting of wide lateral strips containing varied topographical elements and populated by autochthonous grass, shrub, and tree species.

For rehabilitation to be successful, proper planning and interaction with stakeholders must complement the
ecosystem perspective listed above. Socioeconomic considerations will play a large role in determining where and
when different rehabilitation measures are applied. (WMO 2006a)