Accurate estimation of the spatial and time variation of rainfall across urban catchments is essential for accurate sewer and stormwater modelling and operations activities.
The Auckland region is served by an extensive rain gauge network operated by Auckland Council Healthy Waters Department. In light of the difficulties in achieving even the minimum desirable density of 1 gauge / 1-4 km2 across the entire region (the land area of the Auckland region is some 5000 km2 and experiences highly variable rainfall) the authors have been working collaboratively towards enabling use of rain-radar derived accumulations to support decision making in real time during flooding events, immediately post event for reporting to stakeholders and in long term planning.
To date, use of rain radar derived quantitative precipitation estimates in the engineering field has been hampered by the large data volumes which need to be handled and the high level of specialised expertise required to quality control and calibrate raw radar observations. In order to remove this barrier and foster more widespread use of radar data, data quality control from the Auckland MetService radar has been automated, operationalising real-time calibration of the radar precipitation estimates using the Auckland Council rain gauge network. The high quality radar derived accumulations (1 minute time step, 500m resolution rasters) are then fed into a cloud-based GIS platform and can be interacted with by council staff, for example to extract a catchment averaged accumulation or raster stack for model input.