Ratio of Rivers Slightly Polluted/Unpolluted
Terrestrial protected areas
PSBR model type
6.3 By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.
Aichi Biodiversity Targets
Target 8: By 2020, pollution, including from excess nutrients, has been brought to levels that are not detrimental to ecosystem function and biodiversity.
Biodiversity Action Plan
D43010 Formulate improvement plans and schedules for river pollution to reduce the nutrients and heavy metal content of rivers and estuaries to the international standards year by year. Action plan performance indicators:
- The length ratio of the river whose water quality reaching the standard of no hypoxia and no smell (DO>2mg/L).
- The number of estuaries with marine environmental quality reaching Class A and Class B standards.
Rivers are important freshwater resources that connect lakes, estuaries, coasts, and marine ecosystems. Due to Taiwan's dense population, rivers close to populated residential, agricultural, and industrial areas are vulnerable to pollution. When a river is polluted, not only the river and the environment nearby is affected, but it also deteriorates the soil conditions and indirectly affects the health of the organisms in surrounding areas. To ensure the water resources are clean and the river ecosystem is not polluted, the smaller the length ratio of serious polluted rivers the better, and the greater the length ratio of unpolluted/slightly polluted rivers the better.
Definition and Calculation
Based on the River Pollution Index (RPI) published by Environmental Protection Administration, Executive Yuan, the ratio of the length of the slightly polluted/unpolluted river to the total length of the river is calculated. RPI is calculated with the concentration of dissolved oxygen (DO), biochemical oxygen demand (BOD), suspended solids (SS), and ammonia nitrogen (NH3-N) in the river water. The calculated indicator value is used to determine the degree of river pollution. River pollution indicator = (length of un/barely polluted rivers + length of slightly polluted rivers) /total length of the monitored rivers.
According to the information on the website of Environmental Protection Administration, Executive Yuan, the proportion of rivers better than the standards of slightly polluted rivers in Taiwan is about 75%. Compared with 2017, it decreased by about 3.4%.
Since 1988, the proportion of slightly polluted/unpolluted rivers in Taiwan has ranged from 70% to 80% in the past 30 years.
Data Management Authorities
Environmental Protection Administration, Executive Yuan