Updated; 2003-09-03 Top 7th workshop History Links Contact

Ralph Cheng(USGS) Masayuki Oote(PWRI)
Ralph Cheng described how streamgaging data are used for resource appraisal and allocation, design of water infrastructure, flood hazard planning, and flood forecasting. A large percentage of the over 7000 gaging stations operated by the USGS posts river discharge on WWW at near real-time. However, the river discharge is not directly measured; rather it is derived from a stage-discharge relation. There is a need to improve streamgaging technologies to allow river discharge measured directly at near real-time for delivery to users. Systematic research and development efforts at the USGS have shown that it is possible to determine river discharge using non-contact radar systems. The present state-of-the-technology allows reliable measurement of river surface velocity from a riverbank, but the channel cross-section must be determined using ground-penetrating radar (GPR) with the radar beam pointing normal to river water surface. The USGS plans to continue this pursuit with the emphasis on a better understanding of the river hydraulics. The advances achieved from bank-side mounted radar system for river discharge leads to the concept of an air-borne radar system that measures river discharge from a helicopter. The helicopter system is suitable for emergency responses in regional floods and for applications to regions that are difficult to gain access.

Cheng also described how, as part of an urban geologic and hydrologic natural hazards initiative, the USGS attempts to build a near-real time flood simulation and warning system to complement streamgaging in flood prone river basins. The proposed system consists of the integration of an atmospheric forecast model, a regional hydrologic model that sets the appropriate boundary conditions for a hydraulic model to simulate normal and flooding river conditions. The unstructured grid UnTRIM model has been shown to be robust and efficient for simulating flood inundation in urban areas. Models in the integrated system will be running concurrently and interactively. When this system is successfully built and proven valid, the system will be used for flood forecast and for issuing flood warning at near real-time via the internet. In summary, the USGS is attempting to advance technologies in streamgaging, flood hazard studies, and flood warning for near real-time operations.

Masayuki Oote reviewed PWRI's research into hydrologic observations of flood flows using floats, as well as PWRI's interests in new observation technologies to replace the present float observation (or to compensate for the disadvantages of float measurements). PWRI is doing field research on the influence of bridge pier disturbance on flood flow measurement; 3-dimential structure of parallel spiral flow and its impact on the use of floats; and conversion factors to obtain vertically-averaged velocity by using non-contact surface velocity measurement methods, pressure-type Flood Current Meter, and ADCP.

Presentation(PowerPoint slides;PDF file)

Ralph Cheng


Preserntation(PowerPoint slides;PDF file)

Masayuki Oote

Related Information

-'Evaluation of UnTRIM Model for 3-D Tridal Circulation'

-'River discharge measurements by using helicopter-mounted radar'