Water Pollution Continuous Monitoring Technology in Japan
Verification and Utilization of Monitored Data
-Annual environmental report, as the report issued by the prefectural governor to report environmental conditions and its measures to the prefectural assembly.
-Annual measurement report of water pollution in public water areas
Osaka Prefectural Government issues the annual environmental report every September, about 6 months after the end of the fiscal year. The annual measurement report of water pollution, which has more detailed information than the annual environmental report, is issued every December, about 9 months after the end of the fiscal year.
Just as a prefectural governor is given the privilege to monitor pollution, each mayor of city with a population greater than a specified value (e.g.250,000 people) is given the privilege to obtain necessary data from the prefecture and release the report of its city. Data obtained by prefectures and cities are stored on magnetic tape and used as reference data when designing various environmental programs. Recently, some local governments such as prefectures, cities have been releasing environmental data on internet home pages.
In the case of Osaka City Government, the summary of measurement results is carried on the annual environmental report of Osaka City, and all measurement results are listed in annual measurement report of water pollution in public water areas of Osaka City. In addition, various forms of information such as graphs are generated by the Osaka City Environmental Information System for ease of understanding by Osaka citizens. The information is provided to the citizens via the Osaka City Environmental Information Center and the Eco Museum of Osaka.
a. The overall compliance to the Environmental Quality Standards of each river is displayed on a river map using easily understandable illustrations.
b. The measurement results (BOD, etc.) at each monitoring point of rivers in Osaka City are displayed on a river map using graphs.
c. The yearly changes of measurement result (BOD, etc.) at each monitoring point of rivers in Osaka City are displayed on a river map using graphs.
d. The measurement results (COD, etc.) at each monitoring station in Osaka City are displayed on a river map using graphs.
e. The data measured by each monitoring station can be formulated into various graphs simply by selecting the measurement item and yearly / monthly / hourly changes, etc.
(2) Water pollution monitoring station
a) Variations within a given day, week, month or year
Data variation in a given 24-hour period is checked using hourly values, whereas variations within a given week, month or year are checked using daily average values.
b) Variations in water quality due to the influence of water from the Yodo River (measured at Neya River Station)
Since the Neya River is an urban river with significant pollution, water is pumped from the Yodo River to clean the Neya River. The cleansing effect of the Yodo River water is analyzed by comparing the Neya River water quality before and after water is fed into it from the Yodo River.
c) Monitoring water temperature at the Daini-Neya River Station
Among the 6 rivers monitored automatically by Osaka Prefectural Government, the Daini-Neya River has the highest water temperature. Various analyses have been performed to identify the cause of the high water temperature.
d) Comprehensive water pollution index to evaluate river pollution
Although various items are used to monitor pollution, it is difficult to evaluate river pollution using only specific items. Therefore, 6 automatic monitoring items (excluding cyanide) and weather items (rainfall and solar radiation) are used as data for the comprehensive water pollution index to evaluate the pollution of a river.
e) Variations in water quality due to rain
Non-automatic measurements of river water cannot be performed on a day when it is raining heavily. However, automatic monitoring stations can collect data throughout the year regardless of weather conditions. Therefore, the data collected by automatic monitoring stations can be analyzed to understand the characteristics of river water with and without the influence of rainfall.
f) Surveillance after a fish kill or oil leakage
After a fish kill in a river, water temperature variations and DO levels are analyzed along with other factors, to determine the cause.
g) Abnormally low water level of river
During a drought, abnormally low water levels of river increase turbidity and conductivity. These water characteristics are also analyzed using data measured by automatic monitoring stations.
