Environment The Poetry of Marshlands Turning Back the Clock: Kushiro Marshland Restoration Progress 1970s-2000s

Environment The Poetry of Marshlands Turning Back the Clock: Kushiro Marshland Restoration Progress 1970s-2000s

Until the 1970s, Kushiro Marsh was undergoing river straightening projects in stages for the purpose of flood protection and land use expansion. According to records kept by the Ministry of Land, Infrastructure, Transport, and Tourism (MLIT), from the 1920s to the 1980s, the Kushiro River and its tributaries were converted from meandering streams to short-cut channels, and the old river channels remained as river trace lakes, while the water level on the flood plains declined and the marshlands became increasingly dry. In the process, the ecosystem and landscape were drastically transformed, and the habitat of diverse organisms unique to the marshlands was being lost. The policy of the time was to place the highest priority on flood control and agricultural land expansion, with little regard for the impact on the natural water cycle and biodiversity.

In the late 1980s, however, the situation began to change dramatically: in 1987, Kushiro Marsh was designated as a national park, and its conservation value was officially recognized by the government. In 1993, the Conference of the Contracting Parties (COP5) to the Ramsar Convention on Wetlands was held in Kushiro City. In response to this trend, the River Law was revised in 1997, and "improvement and conservation of river environment" was newly specified in the law, positioning environmental conservation as a policy goal along with flood control. In 1999, the Kushiro Marshlands Study Committee was established, and the entire basin was rehabilitated as a natural environment.

The main pillar of the restoration was the "restoration of the old river (meandering restoration). The Ministry of Land, Infrastructure, Transport, and Tourism (MLIT) has indicated a policy of restoring the straightened sections to their original meandering as much as possible, and the Kayinuma area of the main river (about 2 km) was selected as a pilot site for this restoration. The Ministry also indicated plans to restore the meandering shape of the Hororo, Yukuri, Numaoro, Osobetsu, and other tributary rivers within a period of about five years. The objectives were to optimize the frequency of flooding, restore floodplain vegetation, control downstream runoff of nutrients and sediment, and restore habitats for fish and aquatic insects, as well as the wetland landscape itself.

The restoration implementation scheme was also unique. Under the Kushiro Marsh Nature Restoration Council, the national government (Kushiro Development and Construction Division, Hokkaido Development Bureau), local government, research institutes, and local residents shared the roles and responsibilities. The "Kushiro style" approach was adopted, which involved a series of subtle improvements at the microtopographic level, such as partial lowering of levees, blockage of old drainage channels, and creation of wands and shoals. This was not just a construction project, but also an experimental site for complex natural regeneration that combined the knowledge of engineering and ecology.

It is also important to note that public participation was incorporated into the project from an early stage. Kushiro International Wetland Center (KIWC) surveyed changes in aquatic organisms, vegetation, sedimentary soil, and landscape in and around the meandering restoration section in cooperation with citizens to "visualize" the impact of straightening and improvements after restoration. These survey activities were also linked to school education and observation groups, and conservation activities became a source of pride and learning opportunities for the community.

The background of the times was a growing sense of crisis over global wetland loss and a major shift in policy from "development" to "nature restoration" in Japan after overcoming pollution problems during the period of rapid economic growth. Tourism values also shifted from "seeing" to "learning/being involved," and the concept of sustainable use of local resources spread. Symbolic of this shift was the full-scale meandering restoration project conducted from February 2007 to March 2011. The project had four goals: "ecology," "flood control," "water quality," and "landscape," and reported multifaceted results, including restoration of floodplain vegetation, improvement of aquatic habitat, and reduction of downstream wetland load through nutrient and sediment trapping.

In short, the restoration of Kushiro Marsh is an effort to "untangle the straight line and put time back into the marsh," a multilayered and long-term process that involves setting a direction in institutional terms (national park designation, Ramsar Convention, river law revision), restoring water and soil circulation through meandering restoration connecting engineering and ecology, and obtaining sustainable support through citizen monitoring and learning. It was a multilayered, long-term process. In this process, the marshlands came to be reevaluated not as mere landscape assets, but as "the foundation of society" that unites flood control, water quality, and biodiversity.