III. 26.
FRICS -- A RIVER INFORMATION SYSTEM IN JAPAN --
Fumio Yoshino
Foundation of River & Basin Integrated Communications, Japan (FRICS) was established on October 1985 and began to disseminate hydrological information from June 1986 to the public, using the specially designed FRICS terminals and applying the Videotex system. At present, hydrological data collected from 23 radar raingages by the Ministry of Construction (MOC) and around 7,000 telemetric rain or water level gages etc. by MOC or Prefectural Government are processed to understandable images and provided on a 24-hour basis through FRICS terminals to more than 3,000 users in Japan.
Nine years have passed since the FRICS system was put into operation and one can now say that the system has proved extremely useful in providing information at times of typhoons, floods and droughts for disaster-prevention during these years. At the same time, efforts have been made at FRICS every year for improving the services provided by increasing the quantity, as well as the quickness and accuracy, of the data provided. Among them the development of FRICS terminals such as new standard type, personal type and concurrently the improvement of host computer system for the addition of data communication function so called Tele-software are quite significant.
Furthermore new technologies like satellite communication system, digital communication system or provision of rainfall and flood forecasting data through FRICS terminals are considered to be inevitable in near future. Therefore they are now being studied eagerly. In this paper, not only conventional FRICS systems but also major hydrological data acquisition and dissemination systems in Japan are reviewed.
The Ministry of Construction (MOC) and other bodies responsible for the administration of rivers have been developing hydrological data acquisition by telemetry and radar rainfall information systems, for accurate and speedy collection of rainfall, water level and other hydrologic data through their own networks, in addition to information from weather observation network operated by the Japan Meteorological Agency (JMA). These information are important not only as disaster-prevention information used in protecting people's lives and properties, but as information to be used in people's daily lives and industrial activities.
JMA collects the meteorological data of 5 types (precipitation, wind speed, temperature, atmospheric pressure, humidity) through the commercial telephone line of about 1313 stations (including 473 stations observing only precipitation) over Japan. This system calls as the Automated Meteorological Data Acquisition System (AMeDAS). Also JMA monitors the meteorological phenomena through weather radar network (19 digitized weather radars, c-band) and Geo-stationary meteorological satellite.
The river information system -- which is composed from automatic acquisition system of hydrologic data (precipitation, water level and released discharge through reservoir, etc.), transmission system for observed data, processing system for the data, and distribution and utilization system for processed data -- was first built in 1975, and after continuous enhancement was finally completed as an information system in 1983, by MOC. Since then, MOC has striven to enhance the system at various levels, such as increasing the number of telemeters at observation stations and reporting interval from 1 hour to 30 min. Recently, 10 min rainfall and water level reporting through telemetry are being introduced in the system.
The number of precipitation and water-level telemeter observation stations in rivers under MOC jurisdiction is 3,232 as of March 1990, or an increase of nearly 1.9 times over 1,705 in April 1979. These stations automatically transmit observational data to Work Offices of MOC at certain intervals. Collected data is processed via computers and sent via private radio communications to related Departments in MOC.
The radar raingage system is intended to achieve the areal observation of precipitation and monitoring of the evolution of precipitation phenomena, and to forecast short-term rainfall through the echo movement observed during successive periods. Already 23 radar raingage were installed and finally the network of radar will consist of 26 radars. The system uses 5.7cm wave length and has the observation range of 120 km ( see Table 1). The network is shown in Figure 1.
Rainfall rate of Radar is estimated the Z-R relations, which are determined by regression analysis between observed one hour rainfall on the ground and the received power of radar for 10 to 20 rainfall events. The accuracy of the radar rainfall depends on the storm events, but generally, the standard deviation of estimated radar rainfall to ground rainfall is evaluated as less than 3 dB for rainfall rate more than 10 mm/hr.
Hydrological information, which is collected by MOC, Prefectural Governments and JMA, is used for the river administration by their private use. The information is necessary for for the flood forecasting and warning and also for the operation of hydraulic structures. The collected hydrological data are analyzed and the results are transmitted through official communication lines among organizations concerned, if necessary.
Since 1956, nationwide radio communications networks (exclusive microwave circuits of MOC) for the purpose of transmission of flood fighting information have been built covering about 827 of 1011 MOC agencies (Regional Construction Bureaus, Work Offices, Branch Offices, etc.) throughout the country. The networks are used not only for telephone communication, facsimile transmission and telephotography, but also for data transmission. Regional Construction Bureaus of MOC have been linked with Prefectural Governments by multiplex radio communication lines (microwave circuits) since 1967.
Table 1. Typical specification of radar raingage
|
1. Radome |
|
|
Maximum wind velocity Diameter Type |
Instantaneous 75 m/s 7 m Solid Laminate |
|
2. Antenna |
|
|
Type/Dimension Polarization Gain (main axis) Beam width Side robe |
Circular Parabola / 4m f Horizontal Pol. More than 42 db less than 1.2 degree more than 28 db |
|
3. Antenna Control Unit |
|
|
Revolution Type of Driving Resolution of Azimuth Signal control range |
5 rpm ± 5 % servo - motor
more than 12 bit AZ: 0~360 degree EL : -2 ~ 44.9 degree |
|
4. Transmission and Reception Unit |
|
|
Frequency Peak Power Pulse repetition frequency Transmitted Pulse width Transmission Tube Noise index Minimum received power |
5,260 MHz 250 KW ± 10 % 260 pps ± 2 % 2 m s ± 10 % Magnetron less than 5 db less than -107 dbm |
|
5. Signal processing unit |
|
|
A/D conversion
Averaging of signals
Cancellation ratio of MTI |
Quantization of received power: 12 bit Time resolution of received signal: Range average: 6 samples Azimuth Average: 9 bits more than 25 dB |
Fig.1 - Location of MOC Radar Raingages
Governor of Municipalities direct and supervise flood fighting activities and are directly responsible for the evacuation of residents in case of flooding. They are provided with warning on released discharge form reservoirs, flood fighting warnings, and flood forecasts by MOC. Some municipalities obtain hydrological data through flood fighting radio communications system, disaster prevention radio communications system, or cable telephones by assigning observers on field duty.
The meteorological agency releases weather advisories, warnings, and information pursuant to the Weather Service Law.
The river authorities are required under the Flood Fighting Law to release flood forecasts and flood fighting warnings and to inform all parties concerned accordingly. In the case of larger river basin (designated flood forecasting rivers), if the rivers are considered likely to flood, the Minister of Construction is required to inform a flood forecasting indicating water level or discharge to the Prefectural Governors concerned in cooperation with the Director-General of the Japan Meteorological Agency under the Flood Fighting Law .
Generally, the types of flood forecast and criteria for issuance are as follows:
a) Flood advisory; Issued when the water level is foreseen to exceed the warning water level at least at one flood forecast station.
b) Flood warning; Generally issued when the current water level has already exceeded the warning water level and is foreseen approaching or exceeding the design height of water level, or when the danger exists that levee collapse or some other major disaster will occur.
c) Flood information; Issued to update previously issued flood advisories or flood warnings, or provide information concerning the scale of flooding.
Table 2 shows many actual types of flood fighting warnings and their criteria for issuance. In order to transmit flood forecasts and flood fighting warnings speedily and accurately, a regular text has been standardized for issuance.
The information issued from MOC is transmitted to outside users (flood fighting organizations, local municipalities, mass media, etc.) through the telephones or facsimile equipment operated on commercial telephone lines for data transmission. Therefore sometimes the delay of transmission occurs among the related organizations.
Table 2. Examples of flood fighting warnings and criteria for issuance
|
Types of |
Meaning |
Criteria for issuance |
|
Standby |
1. Flooding or repeated rising of water levels is foreseen and flood fighting organizations must prepare for immediate mobilization as circumstances dictate. |
Issued when weather advisories/warning or river conditions are recognized as dictating such conditions |
|
Prepare. |
preparation for mobilization, await contact on flood fighting activities, prepare equipment, inspect sluice functioning, etc., and strive to secure communications and transportation |
Issued when recognized as necessary in accordance with precipitation, water level, discharge or other river conditions |
|
Mobiliz. |
Flood fighting organizations must mobilize. |
Issued when the warning water level is in danger of being expected, based on flood advisories, etc., or river conditions (water level or discharge, etc.) |
|
Indication |
Water level, flood time or other information needed in floof fighting activities must be communicated, along with information justifying warning based on overtopping, overflow, collapse, fissure or other river conditions |
Issued according to flood warnings or when the water level hs been exceeded and the danger of disaster exists |
|
Cancel |
The series of flood fighting warnings issued by the key stations in question are to be canceled as flood conditions requiring flood fighting activities have dissipated |
Issued when water level has fallen below the warning water level, or, if not, when river conditions requiring flood fighting activities are recognized as having dissipated |
An analysis has been made of changes in transmission time and errors in transmission drills for flood forecasts and flood fighting warnings performed each year by the River Department of a Regional Construction Bureau of MOC since 1960. The analysis during the 16-year period extending from 1971 to 1986, showed a gradual improvement in the transmission time and precision of transmitted drills since 1979 when it was switched from the use of oral messages to that of written messages for facsimile transmission. The rate of errors in fax messages in and after 1985 has been only one sheet out of every 10 sheets. The transmission time ranged from a minimum of 20 minutes to a maximum of 50 to 60 minutes, averaging 30 minutes. Further improvements are considered very difficult to achieve, if the new transmission measures will not be developed (Figure 2).
Fig.2 - Change of transmission time required for Flood Advisories and Warnings
The Foundation of River and Basin Integrated Communications, Japan was established to receive original hydrological data from river authorities, and to provide it to users in the form of image information authorized by river authorities after processing. In other words, the establishment of the Foundation was aimed at constructing a river and basin information management system. In view of the necessity of public announcement of flood fighting information, it was considered to further enhance to transmit a wide variety of flood fighting information on a real-time on-line basis to all parties concerned. This was one reason to establish the Foundation for the purpose of hydrological data transmission to the public.
Table 3. Numbers of Radar Sites and Telemeter Stations
|
Radar |
Rainfall |
Water |
Water |
Snow |
|
|
Region |
Site |
stations |
level |
quality |
depth |
|
stations |
stations |
stations |
|||
|
Hokkaido |
4 |
225 |
228 |
8 |
15 |
|
Tohoku |
3 |
254 |
228 |
24 |
20 |
|
Kanto |
4(1) |
218 |
266 |
33 |
11 |
|
Hokuriku |
3(1) |
159 |
120 |
11 |
19 |
|
Chubu |
2 |
246 |
159 |
11 |
2 |
|
Kinki |
2 |
163 |
163 |
12 |
8 |
|
Chugoku |
2 |
196 |
167 |
13 |
39 |
|
Shikoku |
2(1) |
116 |
67 |
3 |
|
|
Kyushu |
3 |
241 |
196 |
21 |
|
|
Okinawa |
1 |
11 |
11 |
||
|
Total of MOC |
26(3) |
1,829 |
1,605 |
136 |
114 |
|
Total of local |
|||||
|
public bodies |
1,442 |
1,711 |
|||
|
Total |
26(3) |
3,271 |
3,316 |
136 |
114 |
The FRICS system in operation is a private videotex system, which receives various items of information related river administration including reservoir operations and sediment control in the MOC and other river administrators, and transmits them to user's terminals in the form of picture images after processing them on the data processing units at the 10 Regional Centers of the Foundation. Table 3 shows the hydrological data assembled and processed in the FRICS system. Figure 3 shows the communication links among river authorities (MOC and Prefectural government), Municipalities, and Residents through FRICS system. The Foundation is intended to be the sole official organization responsible for communication of river and basin information through an exclusive communication channel.
Fig. 3 - Generalized information flow diagram of FRICS System
At present, hydrological data collected from 23 radar raingages by MOC and 3,271 telemetric raingage data, 3,316 telemetric water level data, 136 water quality data, and 114 snow depth data by MOC or Prefectural Government, are processed to understandable images and provided on a 24-hour basis through FRICS terminals to more than 3,000 users in Japan. Recently the several weather forecast information are also transmitted through the FRICS system (see Table 3). For reference, the total land area of Japan is approximately 370.000 km2.
Recently, meteorological information of 5 types is received from JMA through Japan Weather Association, concerning general weather forecast of one week over Japan, typhoon course prediction, meteorological warnings, weather chart and local weather prediction. Those information is also disseminated through FRICS system.
The system is capable of on-line and off-line input of not only flood fighting information but also a variety of other information relating to the river and basins and is also capable of transmitting the information to all parties concerned. The whole of Japan has been divided into 10 regions and the hydrological information are received at the Regional Centers from the Regional Construction Bureaus of the MOC. The flow of information through FRICS is shown in Figure 3. The system is also designed to permit every terminal to access all the host computers equipped at the Regional Centers. The reason for using multiple host computers for distribution of river information throughout the country are as follows:
a) The pluralization is effective to cope with troubles.
b) Separate regional systems are indispensable for monitoring and inputting flood fighting warnings, rainfall and water level information, and off-line information.
Radar raingage information and telemeter information collected at Regional Construction Bureaus of the MOC is transmitted on-line real-time at 4,800 bps to the systems of the Regional Center of the FRICS. Other off-line information is inputted from manually inputting terminals and image inputting units. The processed information is displayed on the CRT. The operation is done by the keyboard of the terminal and hard copies of the displayed information can be obtained as the need arises.
Warning inputs are converted into sounds and transmitted into registered commercial telephones. They are also transmitted by telop to the CRT of terminals and to the buzzers and lamps of the communication display units of terminals. The functional relationships of the system are illustrated in Figure 4.
A special terminal was developed for the reception of information from host computers. The user accesses to the Regional Center via a telephone line network and receives information. User can receive information one-by-one or several images as a "package". The successive reproduction of past radar image is possible as the function of terminals. Thorough consideration to save telephone charge as well as access time is incorporated.
Standard terminal (personal computer) equipped with 32-bit CPU are to be used for processed picture information using videotex tele-software information. The terminal has next characteristics:
a) Simultaneous reception, display and copy of information received.
b) Storage of large-quantities of received data (100 images on floppy discs and 100 images on hard discs).
c) Multi-window display of up to 4 different types of images on the same screen.
d) Compatibility with the standard software used in Windows and DOS-V.
These are light-weight, portable terminals allowing easy access to information, to be used to supplement the terminals in use. The personal terminal has the following features:
a) Installation of portable (approx. 3 kg), personal use hardware.
b) River and basin information can be obtained anywhere and at any time through telephone lines.
c) Batch image reception and successive image reproduction for radar echo movement.
d) Compatibility with the standard software used in Windows and DOS-V.
Table 4 shows the types and images provided by Tokyo Regional Center. Radar rainfall data, telemeter information, and warnings are updated every 15 minutes, at one-hour intervals, and from time to time, respectively. The number of images updated per day is about 28,000 for on-line real-time information only. Foundation bulletins and other off-line input information are updated once from a day to a month and at present 400 to 800 sheets are inputted for each Regional Center of the Foundation. If a Center suspends its information service due to a trouble or maintenance work, users can access neighboring centers to obtain radar rainfall data and other necessary information.
In addition to the transmission of legally designated warnings, such as flood fighting warnings, flood forecasts and warnings, FRICS notifies its users the warnings, when the rainfall near and upstream of the user's city reaches certain values (e.g. hourly rainfall of 30 mm and cumulative rainfall of 80 mm) or when the water level reaches designated, warning or design flood discharge levels.
Table 4. Information provided by Tokyo Regional Center
|
Item |
types |
images |
|
Radar raingage data Telemeter rainfall data Water level data Dam storage data Snowfall data Water quality and temperature data Warning information News on river administration, etc. Weather information |
10 9 8 4 3 3 9 9 5 |
95 267 365 8 8 41 406 540 15 |
Such warnings are displayed on a CRT screen as telop, but when the CRT screen is not used, the attention of users are called by an automatic warning device built into the terminal to access a Regional Center of the Foundation. This is done through the lamps and buzzers on the user terminals and through the automatic voice generator units connected to the home telephones of up to two persons responsible, in case there is no-one at the terminals.
From the standpoint of flood fighting, these functions have been incorporated into the FRICS system to enable the Foundation to play a leading role in flood fighting activities by making the fullest possible use of the system. Figure 5 shows the communication channels for flood fighting warning. Thus the FRICS system ensures that all useful information for flood fighting purpose is made available to its users.
The Foundation has studied measures for coping with a rush of information requests from users during flood. The system has two measures for the purpose. However, these measures has not been taken due to the continuous improvement of computer ability and the increase of telephone lines.
a) Restrictions will be on the number of picture images to be transmitted in response to each information request made to the host computer. The number is variable, but at present, it is fixed at 10 picture images.
b) The number of picture images to be prepared for transmission is limited to a predetermined number when the director of the Regional Center has decided.
Fig. 5 - Communication channels for flood fighting warnings
At the end of June of 1995, totally 3,172 standard terminals are used in Central Government (751, 24% of totals), Prefectural Government (815, 26%), Municipalities (1,032, 33%), Public Corporations and Public Utilities Companies (414, 12%), and Private Sectors (160, 5%). The 839 personal terminals are now mainly used in the Central Government(792, 94% of total).
Number of images provided annually
The utilization of the FRICS system through ten Regional Centers of the Foundation from April of 1994 to March of 1995 is summarized as follows:
a) Total number of images provided: Approx. 8,950,000 sheets
b) Maximum number provided in a month: Approx. 1,930,000 sheets (September 1991)
c) Average number provided per access: Approx. 5.4 images.
d)Total frequency of access from terminals: Approx. 1,640,000)
Normally, the number of picture images used in a month is larger during the June-September period in rainy season.
Utilization by type of images
a) Radar information; approx. 3,050,000 sheets provided
b) Weather information; approx. 2,200,000 sheets provided
c)Telemetric rainfall information; approx. 550,000 sheets provided
d)Telemetric water level information; approx. 440,000 sheets provided.
e)Warning information; 100,000 sheets provided.
Radar rainfall data and Weather data accounted for an overwhelming part of the picture images used. Those images providing bulletins of the Foundation was about 940,000 sheets.
Utilization by type of users
a) Central Government; approx. 2,260,000 sheets
b) Prefectural Government; approx. 2,500,000 sheets
c) Municipalities: approx. 2,200,000 sheets
d) Public Corporations; approx. 1,310,000 sheets
e) Private Sectors; approx. 420,000 sheets
Utilization of FRICS system at the Typhoon no.18 (Sept. 1991)
a) Frequency of issue of flood warning; Approx. 743 times
b) Total number of access of the system; Approx. 78,000 times
c) Total number of images provided; Approx. 340,000 sheets
The major problems with the FRICS system in operation are as follows:
a) It is difficult to provide the hydrologic information more flexible, because of the videotex CAPTAIN system. Also, the database of CAPTAIN system is not widely constructed.
b) The compatibility of widely used software is limited in some terminals used in FRICS system.
c) Some FRICS system users call for the creation of data bank for river information to allow them to access to it at any time.
d) FRICS system can provide only the observed results of hydrologic data, and does not provide the forecast of future hydrologic conditions, except the officially issued flood forecasts and warnings.
e) Reception of information sometimes delay because of the operating procedure of terminals. Simplification of procedure is expected, with the improvement of transmitted image charts.
Next FRICS system is now studied to solve above mentioned items. The system will be developed basically as more flexible system of data processing for the hydrological forecasting at the terminal by users. This will meet the recent need of public disclosure of the information.
Advance of electronic communication technology has permitted speedy transmission of a huge amount of hydrological information. This trend is likely to be accelerated in future. However, merely the advanced hydrological information does not constitute an appropriate action to cope with a flood: when the flood actually hit a community, the residents must quickly pick up the most needed information from many hydrological data to fight the flood. For this purpose, it is necessary to get familiar with the meaning of hydrological information in normal period. It may also be necessary to introduce a system which enables differences between normal and abnormal conditions to be distinguished easily.