16 Flood Forecasting and Control
373
In present practice design and operation of an urban sewer network and the corresponding sewage treatment plant is done independently. It would be, however,
much more appropriate to facilitate a joint operation of the urban sewer network
and the sewage treatment plant at the end of the sewage system. This operation is
based on real-time flood forecasts which are computed with the aid of radar rainfall measurements. The goal of this control is to minimize the combined negative
effects of the hydraulic load and the pollution load in the receiving waters.
In order to make this control efficient, precipitation information is required with
a high resolution in space and time since already small differences of precipitation
input into an urban rainfall runoff model result in large differences in computed
runoff. The computed real-time flood forecasts have to be rather accurate at short
term (up to two hours) and maybe less accurate at medium-term predictions (based
on weather radar and satellite data). For the real-time short-term forecasts the data
obtained from one radar will be adequate while for the medium-term composite
radar images from several radars will be required.
The optimum control of the combined sewer-sewage treatment plant system is
based on multi-temporal imagery obtained from ground based weather radar systems.
Figure l6.lO shows an urban drainage system in the city of Bochum, Germany
and the principle of rainfall measurement in real-time to be used for flood control.
Colour Plate 16.C shows a sequence of rainfall fields at 5-min. time increments
in the same area during a storm on July 23, 1996. This information is used as input
Germall Weather Serrice, F.S.W:ll
\
F/(}odjiJrecastiug Gild cOil/rot (/('I1/l'r
•
n ,
ain Gauge
lJ rh .ul Curdllll ent !H e.ts.
U ~1arks(nISs(, Su hcatchmcnt
c:=:J S~ h aflhac h Subc:1tchmrnt
o Olbach Ca tchmenl
I
1I
I
! "; .... ,,,;-1, ...
~---Fig. 16.10. Rainfall measurement by weather radar and raingauges. Example of an Urban
Catchment in Bochum, Germany
373
In present practice design and operation of an urban sewer network and the corresponding sewage treatment plant is done independently. It would be, however,
much more appropriate to facilitate a joint operation of the urban sewer network
and the sewage treatment plant at the end of the sewage system. This operation is
based on real-time flood forecasts which are computed with the aid of radar rainfall measurements. The goal of this control is to minimize the combined negative
effects of the hydraulic load and the pollution load in the receiving waters.
In order to make this control efficient, precipitation information is required with
a high resolution in space and time since already small differences of precipitation
input into an urban rainfall runoff model result in large differences in computed
runoff. The computed real-time flood forecasts have to be rather accurate at short
term (up to two hours) and maybe less accurate at medium-term predictions (based
on weather radar and satellite data). For the real-time short-term forecasts the data
obtained from one radar will be adequate while for the medium-term composite
radar images from several radars will be required.
The optimum control of the combined sewer-sewage treatment plant system is
based on multi-temporal imagery obtained from ground based weather radar systems.
Figure l6.lO shows an urban drainage system in the city of Bochum, Germany
and the principle of rainfall measurement in real-time to be used for flood control.
Colour Plate 16.C shows a sequence of rainfall fields at 5-min. time increments
in the same area during a storm on July 23, 1996. This information is used as input
Germall Weather Serrice, F.S.W:ll
\
F/(}odjiJrecastiug Gild cOil/rot (/('I1/l'r
•
n ,
ain Gauge
lJ rh .ul Curdllll ent !H e.ts.
U ~1arks(nISs(, Su hcatchmcnt
c:=:J S~ h aflhac h Subc:1tchmrnt
o Olbach Ca tchmenl
I
1I
I
! "; .... ,,,;-1, ...
~---Fig. 16.10. Rainfall measurement by weather radar and raingauges. Example of an Urban
Catchment in Bochum, Germany