Length of Natural Riverbank in the Downstream of the Main stem


Attach importance to protect the ecological and flood control functions of the natural riparian zone.







Indicator Details

Original indicator name: Length of Natural Riverbank


Sensitive habitats

PSBR model type

Status (S)

Corresponding targets


6.6 By 2020, protect and restore water-related ecosystems, including mountains, forests, wetlands, rivers, aquifers and lakes. 15.1 By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains and drylands, in line with obligations under international agreements.

Aichi Biodiversity Targets

Target 15: By 2020, ecosystem resilience and the contribution of biodiversity to carbon stocks has been enhanced, through conservation and restoration, including restoration of at least 15 per cent of degraded ecosystems, thereby contributing to climate change mitigation and adaptation and to combating desertification.

Biodiversity Action Plan

D42030 Develop reasonable restoration methods for various ecosystems year by year, and evaluate the effectiveness of natural ecological projects and the survey and monitoring of ecological resources (including rivers and coasts). Action plan performance indicators:

  • Number of restoration methods complying with ecological principles in various ecosystems or results of research and evaluation on practicality (of these methods)

  • (Number of cases where biodiversity has been improved)/(Total number of projects with a funding of 50 million or more) and growth rate


To provide water for human use and protect the safety of residents along the river, governments will build a variety of hydraulic structures (such as dikes and revetments, etc.) next to the riverbanks, but the unnatural hydraulic structures have poor permeability, which barely provides living spaces for organisms, and it will block many biological activities, causes the fragmentation of the riparian habitat, and affect the ecology of the riparian habitat.

Definition and Calculation

According to the official summation report of "Existing River Flood Control Facilities" compiled by the Water Resource Agency, Minister of Economic Affairs, the length of the natural riverbank can be obtained by subtracting the length of hydraulic engineering facilities (total length of dikes and revetments) from the total length of the river. All river management offices and county/city governments fill in the information about the rivers under their jurisdiction, such as the length of the main stem, the embankment, and the revetment each year. However, the total length of the main stem river in the report is the length of the main downstream river, excluding tributaries, wild streams, and unmanaged rivers. The length of dikes and revetments includes other areas such as the downstream main stem and tributaries. In addition, there is no distinction between the length of the newly-built and rebuilt dikes and revetments. Therefore, the calculation method is adjusted as follows: Natural riverbank length = (total length of the main stem river + unmanaged river project)-(total length of newly-built dike + total length of newly-built revetment).

The data and temporal range

Existing river flood control facilities (2001-2019)


According to the official summation report of the Water Resource Agency, Minister of Economic Affairs, the length of natural riverbanks in the downstream of the mainstem in 2019 was 1,415.89 kilometers, a decrease of approximately 11.58 kilometers compared to 2018.


Due to the continuous increase in the length of dikes and revetments, the length of natural riverbanks has decreased year by year. From 2001 to 2019, it decreased by about 348.48 kilometers.

Data Management Authorities

River and Coast Division, Water Resources Agency MOEA

Data sources / URL

Website of Water Resource Agency, Minister of Economic Affairs--Existing River Flood Control Facilities.

Data Development Status


Data Providers

River and Coast Division, Water Resources Agency MOEA

Investigation Year



VIII.1506 (14、15) 06