Amenity Rehabilitation or
Ecosystem Rehabilitation?

September 27, 2009
Hyoseop Woo, Ph. D., PE

KICTContents
 Changes in River Management Practices (inKorea)
 Models of River Rehabilitation
 Cases ofProjects
 Conclusions(Urban)River

Rehabilitation

Functions of River (Water)

Engineering Function• Water/sediment Control• (Water Use)Natural Function

Social Function• Ecological Habitat• Self Purification• Aesthetic Valuehistorical/cultural

Park River(d)NaturalRiver(a)DisasterPrevention
River(b)River Rehabilitation

OccupiedRiver(c)Close-toNatureRiver(e)Models of River Rehabilitation• Amenity Rehabilitation Model• Semi-Ecosystem Rehabilitation Model- Can be sustained only by human‟smanagement (adapted from Dr.Tsujimoto‟s)• Ecosystem Rehabilitation Model- Self-sustained

Amenity Restoration Model (ARM) Focused mainly on rehabilitation of theaesthetic values of river- Aesthetic values: amenity, accessibility,recreation, historical/cultural values- Human-oriented

 More plausible at highly urbanized watershed
and highly developed stream corridor
 Can be called “park river”

Ecosystem Rehabilitation Model (ERM) Focused mainly on rehabilitation of theecological system of river; i.e. selfsustainability of physical and ecologicaldynamics of river More plausible at sparsely urbanizedwatershed and less developed stream corridor
 Can be called “ecological river”

Semi-Ecosystem Rehabilitation Model Focused mainly on rehabilitation of theecological system of river; but it can besustained only with human‟s continuous
support (management) It can be called “close-to-nature river”(Naturnaher Wasser)

Compatibility of Models (to each other)
Park River

Degree of Amenity

Close-to-Nature River/ Ecological River

Degree of Naturalness

Cases of ARM- The Han River in Seoul (first developed in 1986)(The Renaissanceunderconstruction,2009)(Yeoi FerryProjectin Seoul
before2009)(A bird eye view)(A Master Plan of the Renaissance Project-The Yangjae-cheon in Seoul (developed in late1990s)양재천의 공원화 사업

7th ICHE (2006)

The Cheonggye-cheon (developed in 2005)

Sumida River, Japan (from Numata, 2009)

Before (70’s-80’s)(Source: Tokyo Metropolitan Government)

Yangtze River, China(from Numata, 2009)

Before (1990’s)(Source: Wuhan Water Authority)

-The Limat River in Zurich (from C. Goeldi, 2009)

WCWF 2009 KOREA

Cases of Semi-ERM (A demo-project at
Yangjae-cheon, Kwacheon)7th ICHE (2006)

Alterbach (in Austria)

Cases of ERM (Red River in USA)19301990

Space Allocations for Each Model ARM- Flood control space mostly contains spaces for
ecological habitat and historical/cultural spaces

 ERM- Ecosystem space needs not be limited within floodcontrol space.
- It can be larger than flood control space andinterconnected with neighboring terrestrial habitats.

7th ICHE (2006)

Spaces for ARM and ERM

Flood control
space
Ecosysem space

Historical &cultural places

Amenity Restoration Model(ARM) (modified from Dr. Shin‟s)

Ecosysem space
Flood control
space
Historical &cultural places

Ecological Restoration Model(ERM)Sustainability of Each Model• ARM- Mostly related much to the safety of people,

protection of properties and maintenance cost.

• ERM- Indicates the ecological sustainability, whichmeans the ecological system once restored
sustains in the future without degradation

Reference Models for Each Model• ARM- Hard to delineate the „original‟ stream because of along time-span, and moreover, urbanization andchannelization- Naturally focused on landscape architecture andsometimes the restoration of historical places•

ERM- Time-span is usually short and reference model isrelatively easily obtained from the maps, pictures anddata of the stream at reference time

Limitations of ERM in Urban Rivers•

Physical restriction of restoring the stream corridor whichwere already permanently changed with buildings andstreets•

Extreme variations of stream flow with and without rainfalls(urbanization effect)•Water quality problem: a serious constraint on stream
restoration in urban stream•

High land price near urban streams → Realization of “roomfor river” is mostly impossible•Citizens‟ level of eyes: ARM rather than ERM

ARM, ERM – Which one people prefer?

Before rehabilitation (1996)
Under re-construction forrecreational use in Spring 2009
After rehabilitation (1998)
Now in September 2009

ARM vs. ERM - People like which one?

After rehabilitation (2000)

Before rehabilitation (1998)

Now in September 2009
Under reconstruction in Spring 2009

Problems of ARM in Urban Rivers• Susceptible to flood damage due to variousamenity-enhancing works (landscapearchitecture)• Overuse and misuse of material– another environmental damage• Misleading of the concept of river restoration(Ecological restoration is such!?)Ex 1: Flood damage (340mm for
24 hrs exceeding design rainfall of385mm) (Yangjae-cheon; August, 1998)

Vulnerable during construction

Scours at immediate downstream of a weir (Changwon-cheon; July, 2009)

Neglect of nature‟s dynamics

Under construction (July 2009)

Washout during July flood

An artificial island at Deokpung-cheon

Overuse and misuse of material
 Ex 1: Use of quarried stones for low-flow revetment
 Ex 2: Use of large boulders at sandy riverEx 3: Overuse of pebbles for low-flow revetment(from Dr. Kim, Haeju)

Conclusions
 River management practices: changed by thepriority of stream functions considered Two types of river rehabilitation model: ARMand ERM, with semi-ERM delineated River space allocation, concept ofsustainability and time-span of reference
model are different from each model

Conclusions
 Two models are not usually compatible in mostcases; Semi-ERM may be of a compromise Limitations of ERM to be implemented in urbanriver: physical restriction, extreme variation inflow, poor water quality, high land price Problems of ARM to be implemented in urbanriver: susceptible to floods, overuse and misuseof material, and misleading of the concept of riverrestoration
 People‟s preference to each model differ fromdifferent eras and regions – “level of eyes”

Thank you