Challenges from Urban Drainage. Jesper Ellerbæk Nielsen Aalborg University, Denmark Department of Civil Engineering

Transcription

1 Challenges from Urban Drainage Jesper Ellerbæk Nielsen Aalborg University, Denmark Department of Civil Engineering

2 Status for LAWR X-band integration into baltrad Challenges in using baltrad for urban drainage applications

3 LAWR and baltrad LAWR (Local Area Weather Radar) Designed for urban drainage applications High resolution temporal and spatial resolution Located close the catchment Scans in only one elevation Cheap Time integrated Short range Meteorological weather radar Designed for meteorological applications Coarser temporal and spatial and spatial Located far from the catchment Scans in several elevations Expensive Snapshot in time Long range Less accurate C-Band More accurate X-Band Urban Catchment

4 Integration of x-band LAWR The LAWR system scans the atmosphere with a wide vertical beam in one fixed elevation (0 ) with 25rpm Based on marine radar technology - non polar metric and without Doppler Ground clutter is removed by dry weather clutter maps

5 The challenges have been to fit Urban radar data into the meteorological radar data standard Meta data and physical quantity (mm/hr, dbz) Status: 99% done Integration of x-band LAWR (Local Area Weather Radar) Aarhus LAWR is on-line The LAWR data are exchangeable but not fully compatible yet Aalborg LAWR will be on-line soon Agreement between most of the Danish LAWR owners to get their data on-line in baltrad Odim_source.xml now includes all Danish LAWR radars

6 Integration of x-band LAWR LAWR H5 data consists of a single dataset The reflectivity measure Ground clutter information The conversion is performed at the radar site Currently a stand alone application on the radar Collaborating with DHI to make ODIM_H5 the native radar output for LAWR

7 Motivation Urban flooding Impact on the environment Management strategies: Build larger storm drainage systems Diverging the storm water Use the excising systems more efficiently Emergency Decease response Photo: Bente Schou Photo: Nikolaj Photo: Svennevig Nikolaj Svennevig

8 Radar observations and urban drainage Range versus resolution 100m spatial resolution 2km spatial resolution Urban model scale (10m)

9 Final remarks baltrad is operating on a large trans national scale whereas problems in the urban drainage system often are local The flooding of Copenhagen Improved NWP for urban drainage applications Thomas Bøvith, DMI

10 Challenges using baltrad for urban drainage Why is baltrad not directly relevant for urban drainage end-users? Adjustment from dbz to rain intensity Higher temporal resolution Need for historical data Exchange of radar nowcasts

11 Adjustments from dbz to rain intensity Urban drainage end-users are in general not interested in dbz It is necessary to provide rain intensity adjusted products Ground observations are required Rain gauges Disdrometeres In sewer sensores (E.g. flow gauges, water level sensores)

12 Higher temporal resolution 10min or 15min radar data is too coarse for urban drainage applications

13 Higher temporal resolution 10min or 15min radar data is too coarse for urban drainage applications temporal interpolation of the data is needed

14 Higher temporal resolution 10min or 15min radar data is too coarse for urban drainage applications temporal interpolation of the data is needed

15 Higher temporal resolution 10min or 15min radar data is too coarse for urban drainage applications temporal interpolation of the data is needed

16 Need for historical data Analysis of urban drainage system requires often historical data In order to understand what went wrong last week data from this week is needed Evaluation of the statistical performance of the urban drainage system requires long time series (years of data) Are the system failing too often? And where is it?

17 Radar nowcasts are essential for supporting real-time control of the urban drainage system Exchange of radar nowcasts Time for preparation Decision support for control strategies Urban drainage end-users might not be able or interested in producing radar nowcasts Distribution possibilities of radar nowcasts is therefore needed

18 Final remarks Getting the baltrad data into urban drainage action is far from trivial It might be feasible to address some of challenges within the baltrad node software but not all of them Additional urban drainage end-user oriented data treatment/preparation is needed