# The Biological Assessment and Rehabilitation of the World's Rivers: An Overview
## 3 River Rehabilitation  
### Asia  
In Japan, river rehabilitation was boosted by the Nature-oriented River Works (NRW) in 1990 and the amendment of the River Law in 1997, when Conservation and Improvement of the River Environment was inserted as the principal goal [80]. The results of NCRE have been used to create the Information Map of River Environment, which is based on a vegetation map with habitats and rare species listed. The maps reveal trends in Japanese rivers and were used to a great extent in river rehabilitation projects [331]. Although the NRW has been conducted in more than 23,000 cases until 2004 [80], this approach was basically only nature-friendly river engineering. Then, the Act on the Promotion of Nature Restoration in 2002 promoted river rehabilitation in Japan, for instance, the Kushiro [332] and Kamisaigo Rivers [333] where the river was widened, and the number of species increased. In addition, by involving the public from the planning stage, a high level of maintenance and management with low cost have been achieved. More examples are shown in Table S2. Recently, river rehabilitation is spreading from the river to the basin to the ecological network [334] and the implementation of green infrastructure. Japan's river rehabilitation efforts are also dedicated to recovery from disasters. An environmentally friendly disaster recovery manual has been prepared, supported by designated river rehabilitation advisors. In the Republic of Korea, except for very small streams, river management is led by the Regional River Management Agency of the Ministry of Land, Infrastructure and Transport in accordance with the River Act. Under the 2018 Water Environment Conservation Act, the government has developed and operated national river ecological rehabilitation programs. In addition, the Ministry of Environment prepared an administrative and financial support system through the Guidelines for the Promotion of Ecological River Restoration Projects. Those guidelines aimed to enhance the ecological value of rivers in accordance with the government's fiscal decentralization in 2020. Korea achieved great results in terms of flood control, water supply and water quality management by the mid-1990s. However, river ecology did not receive much attention until the late 1990s. The Yangjaeheon River in Seoul, was the first urban river to be rehabilitated in Korea by private capital inducement, and the project received favorable reviews from citizens. Since then, river rehabilitation has been gradually expanded nationwide with state support, including the Anyangcheon River in Anyang and the Cheonggyecheon River in Seoul. Increasingly, river naturalization focused on aquatic ecology has become a major concern in river management. One interesting example is the day-lighting of the Cheongyecheon River, which used to be covered by a highway and is now a river-side park ([[https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration](https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration)]([https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration](https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration))) (Table S2). Singaporean river rehabilitation has primarily been driven by the government. The most significant project has been the naturalization of 3.2 km of the Kallang River (Bishan-Ang Mo Kio Park Project) which was a concrete canal ([[https://ramboll.com/projects/singapore/bishan-park](https://ramboll.com/projects/singapore/bishan-park)]([https://ramboll.com/projects/singapore/bishan-park](https://ramboll.com/projects/singapore/bishan-park))) (Table S2). Monitoring has recorded 59 bird species, 22 dragonfly species, and a family of five freshwater otters using the rehabilitated reach. In China, the need to rehabilitate water quality to national standards was driven by several statutes.