Rainfall measurement based on in-situ storm drainage flow sensors

Abstract

Data for adjustment of weather radar rainfall estimations are mostly obtained from rain gauge observations. However, the density of rain gauges is often very low. Yet in many urban catchments, runoff sensors are typically available which can measure the rainfall indirectly. By utilising these sensors, it may be possible to improve the ground rainfall estimate, and thereby improve the quantitative precipitation estimation from weather radars for urban drainage applications. To test the hypothesis, this paper presents a rainfall measurement method based on flow rate measurements from well-defined urban surfaces. This principle was used to design a runoff measurement system in a parking structure in Aalborg, Denmark, where it was evaluated against rain gauges. The measurements show that runoff measurements from well-defined urban surfaces perform just as well as rain gauges. This opens up the possibility of improving the ground rainfall estimate by the use of flow rate measurements.

Keywords:

• Rainfall measurement
• Runoff measurement
• Measurement station

Acknowledgements

The authors would like to acknowledge Søren Enggaard A/S and C.W. Obel Ejendomme Aalborg for providing a suitable building for this measurement station, and COWI A/S Aalborg for the involvement in the realization of this measurement station.

Additional information

Funding

The work presented in this paper is a part of the Storm and Waste Informatics (SWI) project funded by The Danish Council for Strategic Research.