Flooding in the Shanganagh Catchment
27 November 2002
Micheál Mac Cárthaigh
Dublin Regional Inspectorate
Environmental Protection Agency
Richview, Dublin 14
Tel: (01) 268 0138
Fax: (01) 268 0199
email: m.maccarthaigh@epa.ie
December 2002
FLOODING IN THE SHANGANAGH CATCHMENT 15 NOVEMBER 2002
Introduction
Dún Laoghaire-Rathdown County Council maintains two hydrometric stations in the
Shanganagh Catchment where hydrometric data has been collected for a number of
years. They are Station 10021 Common’s Road on the Shanganagh River and Station
10022 Carrickmines on the Cabinteely River.
The Environmental Protection Agency (EPA) assists Dún Laoghaire-Rathdown
County Council with its hydrometric Programme through site selection, undertakes
calibration flow measurements at hydrometric stations, digitises water level records,
downloads the data logger values, edits the data and processes the water level records
into flow data, where there is a rating available for the station.
Available Data
Hydrometric data has been collected at Station 10021 Common’s Road on the
Shanganagh by the then Dublin County Council and later by Dún LaoghaireRathdown County Council since 12 May 1980. The OTT chart recorder was
upgraded to an OTT Thalimedes data logger on 27 March 2002.
Hydrometric data has been collected at Station 10022 Carrickmines on the Cabinteely
River by the then Dublin County Council and later by Dún Laoghaire-Rathdown
County Council since 13 November 1980. The OTT chart recorder was upgraded to
an OTT Thalimedes data logger on 27 March 2002.
Flow Measurements
Flood flow measurements were taken by the EPA Dublin regional hydrometric team
of the flow in the Shanganagh and Carrickmines River which allowed the EPA to
expand the rating curve for this station.
Station details
The catchment area to Station 10021 Common’s Road on the Shanganagh River is
estimated at 30.9 km² and to Station 10022 Carrickmines on the Cabinteely River 10.4
km². The Irish Grid Reference of the location of Station 10021 Common’s Road is
O 252 230 and to Station 10022 Carrickmines is O 234 242.
Flood Records
(1) Station 10021 Common’s Road
Shanganagh River
The data for the period 12 May 1980- 2 December 2002 is presented in Appendix 1.
The first graph is the hydrograph of the water level record at Station 10021
Common’s
Road and the second graph is the hydrograph of flow for the same period at the same
station.
The hydrographs of (1) water level and (2) flow for the floods of 6 November 1982,
26 May 1993 and 27 November 2002 at Station 10021 Common’s Road are presented
in Appendix 2.
(2) Station 10022 Carrickmines
Cabinteely River
The data for the period 13 November 1980- 2 December 2002 is presented in
Appendix 3. The first graph is the hydrograph of the water level record at Station
10022 Cabinteely and the second graph is the hydrograph of flow for the same period
at the same station.
The hydrographs of (1) water level and (2) flow for the floods of 6 November 1982,
26 May 1993, 18 December 1997 and 27 November 2002 at Station 10022
Carrickmines are presented in Appendix 4.
Flood of 27 November 2002
(1) Station 10021 Common’s Road
Shanganagh River
At 17:45 hrs on Tuesday 26 November 2002 the water level in the Shanganagh River
started to rise at Station 10021 Common’s Road. The water level rose fairly steadily
from 0.55 m and peaked at a water level of 0.92 m at 01:00 hrs (GMT) on 27
November 2002. Water levels then began to decline to 0.84 m at 07:15 hrs on on 27
November 2002. There was a subsequent rapid increase in level from this time until
the final peak of 1.59 m at 13.15 hrs on Wednesday 27 November 2002.
There was then a steady decline in water levels until approx. pre-flood levels were
recorded at 06:00 hrs on 28 November 2002.
Using the rating curve at Station 10021 Common’s Road, the peak flowrate,
corresponding to a staff gauge reading of 1.59 m at 13.15 hrs on 27 November 2002,
was estimated at a flowrate of 12.2 m³/s.
(2) Station 10022 Carrickmines
Cabinteely River
At 15:45 hrs on Tuesday 26 November 2002 the water level in the Cabinteely River
started to rise at Station 10022 Carrickmines. The water level rose fairly steadily
from 0.52 m and peaked at a water level of 0.73 m at 23:30 hrs (GMT) on 26
November 2002. Water levels then began to decline to 0.68 m at 07:45 hrs on on 27
November 2002. There was a subsequent rapid increase in level from this time until
the final peak of 1.16 m at 11:45 hrs on Wednesday 27 November 2002.
There was then a steady decline in water levels until approx. pre flood levels were
recorded at 19:00 hrs on 27 November 2002.
Based on the rating curve, the peak flowrate, corresponding to a staff gauge reading of
1.16 m at 11:45 hrs on 27 November 2002, was estimated at a flowrate of 5.7 m³/s.
Appendix 1
Hydrograph of water level and flow at
Station 10021 Common’s Road on the Shanganagh
River
n Agency
Hydrograph of Water Level
COMMON S ROAD.W.1
COMMON S ROAD.W.15
Station name: COMMON S ROAD
River: SHANGANAGH
W [m]
Station number: 10021
1.5
1.0
0.5
0.0
01/06/1980
01/06/1983
01/06/1986
01/06/1989
01/06/1992
01/06/1995
01/06/1998
01/06/2001Time t
Hydrograph of Flow
COMMON S ROAD.Q.1
COMMON S ROAD.Q.15
Station number: 10021
River: SHANGANAGH
Q [m3/s]
Station name: COMMON S ROAD
10
5
0
01/06/1980
01/06/1983
01/06/1986
01/06/1989
01/06/1992
01/06/1995
01/06/1998
01/06/2001Time t
Appendix 2
Hydrograph of water level and flow at
Station 10021 Common’s Road
on the Shanganagh River
for 6 November 1982, 26 May 1993
and 27 November 2002
Hydrograph of Water Level
COMMON S ROAD.W.1
COMMON S ROAD.W.15
Station name: COMMON S ROAD
River: SHANGANAGH
W [m]
Station number: 10021
1.5
1.0
0.5
0.0
25/10/1982
01/11/1982
08/11/1982
15/11/1982
22/11/1982
Time t
29/11/1982
Hydrograph of Flow
Station name: COMMON S ROAD
River: SHANGANAGH
Q [m3/s]
Station number: 10021
COMMON S ROAD.Q.1
10.0
7.5
5.0
2.5
0.0
25/10/1982
01/11/1982
08/11/1982
15/11/1982
Time t
22/11/1982
29/11/1982
Hydrograph of Water Level
COMMON S ROAD.W.1.O
Station name: COMMON S ROAD
River: SHANGANAGH
W [m]
Station number: 10021
1.5
1.0
0.5
11/05/1993
18/05/1993
25/05/1993
01/06/1993
08/06/1993
Time t
15/06/1993
22/06/1993
29/06/1993
Hydrograph of Flow
Station number: 10021
COMMON S ROAD.Q.1
River: SHANGANAGH
Q [m3/s]
Station name: COMMON S ROAD
10
5
0
11/05/1993
18/05/1993
25/05/1993
01/06/1993
08/06/1993
Time t
15/06/1993
22/06/1993
29/06/1993
Hydrograph of Water Level
Station number: 10021
COMMON S ROAD.W.15
Station name: COMMON S ROAD
River: SHANGANAGH
1.75
1.50
W [m]
1.25
1.00
0.75
0.50
0.25
08/11/2002
11/11/2002
14/11/2002
17/11/2002
20/11/2002
Time t
23/11/2002
26/11/2002
29/11/2002
Environmental Protection Agency
Hydrograph of Flow
Station number: 10021
COMMON S ROAD.Q.15
River: SHANGANAGH
Q [m3/s]
Station name: COMMON S ROAD
10.0
7.5
5.0
2.5
0.0
08/11/2002
11/11/2002
14/11/2002
17/11/2002
20/11/2002
Time t
23/11/2002
26/11/2002
29/11/2002
Appendix 3
Hydrograph of water level and flow at
Station 10022 Carrickmines on the Cabinteely River
Hydrograph of Water Level
CARRICKMINES.W.1
CARRICKMINES.W.15
Station name: CARRICKMINES
River: CABINTEELY
W [m]
Station number: 10022
1.25
1.00
0.75
0.50
0.25
0.00
01/10/1980
01/10/1983
01/10/1986
01/10/1989
01/10/1992
Time t
01/10/1995
01/10/1998
01/10/2001
Hydrograph of Flow
CARRICKMINES.Q.1
CARRICKMINES.Q.15
Station number: 10022
River: CABINTEELY
Q [m3/s]
Station name: CARRICKMINES
6
4
2
0
01/12/1980
01/12/1983
01/12/1986
01/12/1989
01/12/1992
Time t
01/12/1995
01/12/1998
01/12/2001
Appendix 4
Hydrograph of water level and flow at
Station 10022 Carrickmines on the Cabinteely River
for 6 November 1982, 26 May 1993, 18 December 1997
and 27 November 2002
Hydrograph of Water Level
Station name: CARRICKMINES
River: CABINTEELY
W [m]
Station number: 10022
CARRICKMINES.W.1.O
1.0
0.8
0.6
0.4
0.2
13/10/1982
20/10/1982
27/10/1982
03/11/1982
10/11/1982
17/11/1982
Time t
Hydrograph of Flow
Station name: CARRICKMINES
River: CABINTEELY
Q [m3/s]
Station number: 10022
CARRICKMINES.Q.1
5
4
3
2
1
0
13/10/1982
20/10/1982
27/10/1982
03/11/1982
10/11/1982
17/11/1982
Time t
Hydrograph of Water Level
Station name: CARRICKMINES
River: CABINTEELY
W [m]
Station number: 10022
CARRICKMINES.W.1
1.2
1.0
0.8
0.6
0.4
0.2
10/05/1993
17/05/1993
24/05/1993
31/05/1993
07/06/1993
14/06/1993
Time t
21/06/1993
Hydrograph of Flow
River: CABINTEELY
Station name: CARRICKMINES
Q [m3/s]
Station number: 10022
CARRICKMINES.Q.1
6
4
2
0
10/05/1993
17/05/1993
24/05/1993
31/05/1993
07/06/1993
14/06/1993
Time t
21/06/1993
Hydrograph of Water Level
Station name: CARRICKMINES
River: CABINTEELY
W [m]
Station number: 10022
CARRICKMINES.W.1
1.0
0.8
0.6
0.4
12/12/1997
19/12/1997
26/12/1997
02/01/1998
Time t
09/01/1998
Hydrograph of Flow
Station number: 10022
River: CABINTEELY
Q [m3/s]
Station name: CARRICKMINES
CARRICKMINES.Q.1
4
2
0
12/12/1997
19/12/1997
26/12/1997
02/01/1998
Time t
09/01/1998
CARRICKMINES.W.15
Hydrograph of Water Level
Station name: CARRICKMINES
River: CABINTEELY
W [mm OD]
Station number: 10022
1.0
0.8
0.6
0.4
13/11/2002
16/11/2002
19/11/2002
22/11/2002
25/11/2002
28/11/2002
Time t
01/12/2002
Environmental Protection Agency
Hydrograph of Flow
River: CABINTEELY
Station name: CARRICKMINES
Q [m3/s]
Station number: 10022
CARRICKMINES.Q.15
4
2
0
13/11/2002
16/11/2002
19/11/2002
22/11/2002
Time t
25/11/2002
28/11/2002
01/12/2002