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CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
REFERENCE: DG/CB/190/11
FOR
DUMFRIES AND GALLOWAY COUNCIL
&
SCOTTISH POWER
Name Signed Date
Author William Hume 12th
September 2013
Checked By Steven Curran 12th
September 2013
Report No. 1168-202 Version: FINAL
Type Flood Risk Assessment Level Level 3
Revision: 1 Issue Date: 12th
September 2013
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
TABLE OF CONTENTS
SECTION PAGE
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1 INTRODUCTION ....................................................................................................................... 1
1.1 PREAMBLE ...................................................................................................................... 1
1.2 OBJECTIVES OF INVESTIGATION ........................................................................... 2
1.3 REPORT STRUCTURE ................................................................................................... 2
1.4 LIMITATIONS OF REPORT ......................................................................................... 2
2 DATA SOURCES, GEOGRAPHY & HYDROLOGICAL ENVIRONMENT .................... 3
2.1 DATA SOURCES .............................................................................................................. 3
2.2 GENERAL GEOGRAPHY OF THE CASTLE DOUGLAS AREA ............................ 3
2.3 GENERAL GEOLOGY ................................................................................................... 4
2.4 HYDROLOGICAL ENVIRONMENT ........................................................................... 4
2.4.1 Galloway Hydros Scheme ................................................................................................. 4
2.4.2 Hydrological Impact of Hydro Scheme ............................................................................. 5
2.4.3 Impact of Water Framework Directive on the Hydro Scheme .......................................... 5
2.4.4 Carlingwark Lane .............................................................................................................. 5
2.4.5 Carlingwark Loch .............................................................................................................. 6
2.4.6 Watercourse Monitoring Information ................................................................................ 6
2.5 BLACKPARKS PUMPING STATION .......................................................................... 6
3 REVIEW OF RECENT AVAILABLE REPORTS ................................................................. 7
3.1 SCOTTISH POWER REVIEW OF BLACKPARKS FACILITY ............................... 7
3.2 SCOTTISH POWER BLACKPARKS FACILITY REPORT (REV 2) ...................... 7
3.3 SCOTTISH WATER SOLUTIONS CASTLE DOUGLAS WASTE WATER
TREATMENT WORKS FLOOD RISK ASSESSMENT ......................................................... 8
3.4 SCOTTISH POWER GALLOWAY HYDROS CULVENNAN LAND
DRAINAGE PUMPS .................................................................................................................... 9
4 ADDITIONAL INFORMATION INPUTS ............................................................................ 10
4.1 SCOTTISH POWER ...................................................................................................... 10
4.2 DUMFRIES AND GALLOWAY COUNCIL COUNTRYSIDE RANGER .............. 10
4.3 NATIONAL TRUST FOR SCOTLAND RANGER SERVICE ................................. 10
4.4 DUMFRIES AND GALLOWAY LIBRARIES ............................................................ 10
4.5 ADDITIONAL INFORMATION .................................................................................. 10
5 FLOOD RISK ASSESSMENT ................................................................................................ 11
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
TABLE OF CONTENTS
SECTION PAGE
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5.1 MODEL SETUP .............................................................................................................. 11
5.2 RIVER FLOW ................................................................................................................. 14
5.3 MODEL RESULTS UNDER EXISTING GROUND CONDITIONS ....................... 15
6 DISCUSSION AND RECOMMENDATIONS ....................................................................... 17
6.1 FINDINGS UNDER EXISTING CONDITIONS ......................................................... 17
6.2 BLACKPARK PUMP FACILITY ................................................................................ 17
6.3 POSSIBLE MITIGATION MEASURES ..................................................................... 18
6.4 GENERAL CONCLUSIONS ON POSSIBLE MITIGATION MEASURES ........... 19
6.5 OUTLINE RECOMMENDATIONS ............................................................................. 19
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
APPENDIX
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References
Figures & Drawings
Figure 1 – Site Location
Figure 2 – Detail of Carlingwark Lane
Figure 3a – Model Cross Section Locations
Figure 3b – Model Cross Section Locations along Carlingwark Lane
Figure 4 – 1D model cross sections
Figure 5 - Detail of Model Blocked Cells
Drawing 1168-202-C01 – Survey Data supplied by the Council
Drawing 1168-202-D1 – 1 in 2year Peak Water Depths
Drawing 1168-202-D2 – 1 in 5year Peak Water Depths
Drawing 1168-202-D3 – 1 in 10year Peak Water Depths
Drawing 1168-202-D4 – 1 in 25year Peak Water Depths
Drawing 1168-202-D5 – 1 in 50year Peak Water Depths
Drawing 1168-202-D6 – 1 in 100year Peak Water Depths
Drawing 1168-202-D7 – 1 in 200year Peak Water Depths
Drawing 1168-202-D8 – 1 in 200year +GCC Peak Water Depths
Drawing 1168-202-D9 – 1 in 1000year Peak Water Depths
Drawing 1168-202-D1 O – 1 in 2 year with Blackpark Pumps off
Drawing 1168-202-D5 O – 1 in 50 year with Blackpark Pumps off
Drawing 1168-202-D7 O – 1 in 200 year with Blackpark Pumps off
Drawing 1168-202-D1 MIT1
Drawing 1168-202-D1 MIT2
Drawing 1168-202-D1 MIT3
Drawing 1168-202-D1 MIT4
Drawing 1168-202-D3 MIT1
Drawing 1168-202-D5 MIT1
Drawing 1168-202-D5 MIT2
Drawing 1168-202-D5 MIT3
Drawing 1168-202-D5 MIT4
Drawing 1168-202-D6 MIT3
Drawing 1168-202-D6 MIT4
Drawing 1168-202-D7 MIT1
Photographs
Tables
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
1 INTRODUCTION
1.1 PREAMBLE
The physical geography around Castle Douglas is generally flatter that the surrounding
hill land with the Dee valley widening considerably to the east and west. The River Dee
thus meanders through this undulating countryside and exhibits an extensive functional
flood plain.
The Carlingwark Loch has, from earliest historical times, occupied the low lying
marshland to the south of Castle Douglas. The Loch was partly drained by the
construction of the Carlingwark Lane in 1765 to facilitate the excavation and
transportation of marl for agricultural purposes.
The development of the River Dee hydro-electric scheme (the Galloway Hydros Scheme)
in the 1930s included the linking of the Loch Doon and Clatteringshaws catchments to the
River Dee system, which results in an overall increase in water flow through the Dee.
Other elements of the system provide peak rainfall attenuation leading to a reduction in
peak river flow but an overall increase in base flow. The hydro scheme therefore brought
with it an increased seasonal risk of flooding to local farmland and, as a result, a number
of small pump stations were placed in the low lying areas to the west of Castle Douglas.
These pumps, coupled with a series of flood bunds, assisted and continue to assist the
drainage of local farmland.
Notwithstanding the presence of the Blackparks Pumping Station on Carlingwark Lane
the drainage of the area around Carlingwark Loch and Castle Douglas itself remains
highly dependent on the state of the River Dee to the north and west. Raised water levels
in the Carlingwark Loch are known to occur and present a known hazard to the town of
Castle Douglas.
Dumfries and Galloway Council, in partnership with Scottish Power, is seeking to carry
out a flood risk appraisal for the town of Castle Douglas with specific reference to the risk
posed by interaction of the Carlingwalk Loch and the River Dee. Terrenus CDH Ltd was
appointed by the Council to carry out this work.
Cognisance of a number of related flood risk and flood assessment reports for the
Carlingwalk Lane watercourse and Castle Douglas has been included in the assessment
with the effect of the Blackparks Pumping Station being a key element of the study.
The Council is seeking to gather information in order to allow informed decisions to be
made regarding the future of the pumping station and the related flood defences.
First and second drafts of the report have been presented to the Council with initial
findings. This current report represents the Final report and includes comments on a
number of issues raised by the Council and by SEPA together with additional information
where necessary. This report is provided for discussion by relevant parties and will
include data and shape files in separate electronic format.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
J:\Jobs CDH\1100-1199\1168 - Dumfries & Galloway Council\1168-202 - Castle Douglas\7 - Reports\1168-202 Castle Douglas FRA FINAL Rev 1.doc
Page 2 of 20
1.2 OBJECTIVES OF INVESTIGATION
From the project brief and subsequent discussions with the Council the principle aims of
the assessment are to:
“enable Dumfries and Galloway Council to make an informed decision on the criticality
of the Blackparks pump station in protecting Castle Douglas from flooding events
primarily from the Carlingwark Loch and Lane and associated catchment and some
consideration of improvements to the current situation.”
The above broad objective anticipates that a review of the current situation will be carried
out as well as detailed two dimensional flood modelling of the area as a whole under a
variety of circumstances.
Information from the investigation and watercourse modelling was used to inform
possible mitigation measures relating to Carlingwark Loch and Carlingwark Lane.
1.3 REPORT STRUCTURE
The structure of this report firstly sets out the geography and hydrological environment of
the Castle Douglas area prior to considering the historical relationship of the town to the
water environment and, specifically, the Carlingwark Loch.
The detailed model of the Carlingwark Loch, Carlingwark Lane and River Dee surface
water environment is set out and the model results presented.
Finally, potential mitigation measures to reduce the risk of flooding to Castle Douglas
whilst enhancing the local environment are considered.
1.4 LIMITATIONS OF REPORT
Terrenus CDH Ltd. has prepared this report for the sole use of Dumfries & Galloway
Council and Scottish Power, in accordance with generally accepted consulting practice
and for the intended purpose as stated in the related contract agreement. No other
warranty, expressed or implied, is made as to the professional advice included in this
report.
To the best of our knowledge, information contained in this report is accurate at the date
of issue. It should be noted, however, that this report is based on the information obtained
from the sources listed in Section 2 below. There may be conditions pertaining at the site
not disclosed by these sources, which might have a bearing on the recommendations
provided if such conditions were known. We have, however, used our professional
judgement in attempting to limit this during the investigation.
It is important therefore that these implications be clearly recognised when the findings of
this study are being interpreted. In addition, this should be borne in mind if this report is
used without further confirmatory investigation after a significant delay.
The report is not, however, suitable for detailed planning and design purposes.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
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Page 3 of 20
2 DATA SOURCES, GEOGRAPHY & HYDROLOGICAL ENVIRONMENT
2.1 DATA SOURCES
A wide variety of data sources were consulted during the course of the investigation
including:
The Scottish Environment Protection Agency (SEPA) indicative flood risk map;
Current Topographic Maps;
Additional topographic information for Castle Douglas as provided by Dumfries and
Galloway Council;
LiDAR data procured from SEPA via Dumfries and Galloway Council comprising a
5m horizontal grid with a vertical accuracy of +/-50cm;
Aerial Photography of the Castle Douglas Area;
Geological & Hydrogeological Maps;
Scottish Power Galloway Hydros – Culvennan Land Drainage Pumps, November
2009;
Scottish Power Blackparks Facility Report (Rev 2), April 2009;
Scottish Power Review of Blackparks Facility, November 2005;
Scottish Water Solutions Castle Douglas Waste Water Treatment Works Flood Risk
Assessment, October 2008;
Dumfries and Galloway Infrastructure Engineering Guide – Project Risk
Management;
Some Stewartry Sketches, Alistair Penman 1981;
Causewayend to Castle Douglas, Alistair Penman 1986
Discussions were also held with the National Trust for Scotland Ranger service, Dumfries
and Galloway Countryside Ranger, Hydros Manager Scottish Power and SEPA offices.
A full list of references is included in the appendix to this report.
2.2 GENERAL GEOGRAPHY OF THE CASTLE DOUGLAS AREA
The valley of the River Dee in Galloway is clearly defined throughout the hills
surrounding New Galloway and in the vicinity of Loch Ken. The southern part of the
River Dee valley around Tongland is similarly topographically well defined. The physical
geography around Castle Douglas is however generally flatter and gently undulating with
the Dee valley widening considerably to the east and west.
Although the bulk of Castle Douglas is located at a higher level, the area around
Carlingwark, which is fed by the Gelston Burn from the south east, is at a similar level to
that of the wider Dee valley. At the north western periphery of Carlingwark Loch the land
rises slightly, effectively forming a low ridge that impounds flow from the south east
towards the north west and the River Dee. The Carlingwark Lane cuts through this ridge
and allows partial drainage of the Loch.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
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Page 4 of 20
The Carlingwark Lane watercourse also drains the Dee Marshes and agricultural grazing
land between Carlingwark Loch and the River Dee, including the outfall from the
wastewater treatment works for Castle Douglas.
The Dee Marshes are an internationally important ecological site and are registered as a:
Site of Special Scientific Interest (SSSI);
Special Protection Area (SPA); and
RAMSAR site.
The SSSI citation notes that the marshes contain areas of swamp, fen, grassland and carr
woodland and is one of the best examples of a semi-natural freshwater system in north
west Europe. The SSSI site covers an area of some 770ha.
2.3 GENERAL GEOLOGY
The superficial deposits around the existing line of the River Dee and Carlingwark Lane
are dominated by alluvium comprising Silt, Sand and Gravel of Quaternary Period origin.
To the north and east of these deposits Fluvio-glacial deposits are recorded comprising
Gravel, Sand and Silt. Around the Carlingwark Loch the superficial deposits comprise
Glacial Till.
The solid geology below the Castle Douglas area, including the Carlingwark Loch and
Carlingwark Lane, is dominated by deep marine Greywacke sedimentary rocks of the
Silurian Carghidown Formation.
2.4 HYDROLOGICAL ENVIRONMENT
2.4.1 Galloway Hydros Scheme
The River Dee catchment is a managed hydrological environment as part of the Galloway
Hydros Scheme. This hydroelectric system, built in the earlier part of the 1930’s, has a
combined catchment of over 1,300km2 in Ayrshire and Galloway and comprises eight
dams and six power stations together with associated tunnels, aqueducts and pipelines.
Loch Doon lies at the head of the scheme and is a natural loch whose level has been raised
and augmented by diverted flow from the Water of Deuch and the Bow Burn. Prior to the
hydro-scheme Loch Doon solely fed the River Doon which flows to the north. A
compensation flow continues down the River Doon however the scheme now feeds the
headwaters of the River Dee and thus the downstream power stations.
Clatteringshaws Loch is a man-made water body created by the damming of the upper
Black Water of Dee. A compensation flow is released to this watercourse with a further
piped water supply being provided for the Glenlee Power Station. Outflow from this
power station enters the River Dee upstream of Loch Ken. Overflow water from
Clatteringshaws as well as catchment run-off downstream of the loch enters Loch Ken
opposite the village of Parton.
Loch Ken is a naturally flat bottomed valley where, historically, the River Dee has spread
out to form a shallow extent of water during periods of peak flow. The hydro scheme
barrage at Glenlochar results in Loch Ken being a larger permanent body of water which
acts as a storage reservoir for the downstream Tongland Power Station. Beyond this final
power station the River Dee enters Kirkcudbright Bay and thus the wider Solway Firth.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
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2.4.2 Hydrological Impact of Hydro Scheme
Since the scheme was completed local records suggest that average annual rainfall in the
Dee catchment has increased by about 20%. In addition, Loch Doon being added to the
River Dee catchment results in an overall increase in flow.
Loch Doon and Clatteringshaws Loch together with the associated catchment connectors
provide attenuation to the peak River Dee flow effectively resulting in a reduction in peak
flow but an increase in base and less extreme flows.
Reports on the impact of the Galloway Hydros Scheme on the River Dee downstream of
Loch Ken estimate that the system increases base flows by some 6m3/s on average
although this increase is highly variable due to seasonal and annual fluctuations.
Management of the hydro scheme seeks in part to reduce the risk of downstream flooding,
chiefly by restricting the flow from Loch Doon and Clatteringshaws Loch during flood
conditions. Loch Ken has a limited storage capacity and during peak flow events the
Glenlochar Barrage is opened such that the output flow from the loch is not impeded.
2.4.3 Impact of Water Framework Directive on the Hydro Scheme
The Water Framework Directive (WFD) was introduced by the European Commission in
2000 and aims to protect, improve and ensure the sustainable management of water
resources. Under the WFD a programme of measures will be implemented in a formal
River Basin Management Plan (RBMP). The Scottish Government has adopted this
directive and, therefore, the Galloway Hydros Scheme as a heavily modified water system
will seek a ‘Good Ecological Potential’ via the provision of a maximum net environmental
benefit without impacting on the operation of the scheme.
The Galloway Hydros lies chiefly within the Solway Tweed River Basin District and
partly within the Scotland River Basin District. As a result SEPA and the Environment
Agency have a joint responsibility for co-ordinating the key areas of work.
A key hydrological impact of the drive towards good ecological potential for the
Galloway Hydros is the maintenance of adequate levels of compensation flow to achieve
the ecological wellbeing of the catchment.
2.4.4 Carlingwark Lane
Carlingwark Lane drains just under 14km2 of land around Castle Douglas, including the
Gelston Burn and the output from Carlingwark Loch.
It has been suggested in the earliest maps of the area that, prior to being partly drained in
1765 by the construction of the Carlingwark Lane, the loch was at a sufficient depth to
allow drainage to the south and the Solway Firth via the Doach Burn. A review of the
local land form and available height data suggests that this was not the case and that the
Loch has always drained to the north to enter the River Dee across the wide flood plain
around Threave Island.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
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Page 6 of 20
In addition to the drainage of Carlingwark Loch the Lane also accepts water from a
number of local drainage channels across the lower lying ground in the vicinity (see
Figure 2). These channels are coupled with a number of bunds that prevent the free flow
of flood waters over the area during extreme storm events. These drainage bunds are
likely to be chiefly agricultural in nature and are not thought to provide any significant
protection against the flow of water during larger storm events such as the design 1 in 200
year event.
2.4.5 Carlingwark Loch
The Countryside Ranger together with local residents indicate that vegetation growth
around the upper end of the Carlingwark Lane (around Buchan Bridge) is known to
become heavy and to impede the flow of water. A number of local residents stated that
this vegetation growth has resulted in periodic raised water levels in the loch itself.
2.4.6 Watercourse Monitoring Information
SEPA runs a gauging station immediately downstream of the Glenlochar Barrage. The
data from this station is severely compromised by the function of the barrage itself, which
controls the normal flow from Loch Ken.
A total of five Scottish Power automatic water level monitors were placed by MWH from
the upstream side of Carlingwark Loch to the confluence of the Carlingwark Lane and the
River Dee. Some 30 months of data was available for three of these monitoring stations;
two of the stations were lost or compromised.
2.5 BLACKPARKS PUMPING STATION
The station is a run of river facility placed within the Carlingwark Lane, adjacent and to
the north east of Meikle Wood Hill. Scottish Power confirms that the station comprises
two sluice gates of 1.5m wide by 1.2m high, each with flap valves which prevent water
flow from the River Dee upstream towards Castle Douglas. In addition, the station
accommodates two pumps to assist the water flow from Carlingwark Loch to the River
Dee. These pumps are rated at 1.35m3/s each and are operated automatically by means of
level switches immediately up and downstream of the pumping station. The pumps are
fully automatic however the precise start up trigger levels are not known.
Potential flood waters are prevented from circumnavigating the pumping station by means
of bunds that connect the station to Meikle Wood Hill to the south and the Blackparks
Smallholdings to the north (Blackparks 3). These bunds show some sign of degradation
and no longer form a level crest height. The lowest point on the bunds is understood to be
at 44.1m OD.
Castle Douglas
Flood Risk Assessment
For
Dumfries & Galloway Council
& Scottish Power
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3 REVIEW OF RECENT AVAILABLE REPORTS
3.1 SCOTTISH POWER REVIEW OF BLACKPARKS FACILITY
This interim report was commissioned by Scottish Power and undertaken by The Carnie
Consultancy and MWH. The report entails consultations with a number of organisations in
the local area as well as some tenant farmers, limited topographic surveying of the area
and an assessment of the Blackparks Pumping Station.
This report suggests that the Blackparks station may have been built to allay fears of
flooding to the land downstream of the Glenlochar Barrage following the construction of
the Galloway Hydros Scheme. The report notes that the area around the Blackparks station
forms part of the Threave Estate. Within the Estate a Special Protection Area and
RAMSAR site lies downstream of the pumping station and a Site of Special Scientific
Interest covers parts of the low lying marsh land around the station.
The report states that the there is no record of the bunds on either side of the Blackparks
station being overtopped. The worst storm event record in the report is in December 1994.
The Countryside Ranger is reported to note that the level of the Carlingwark Loch
typically varies by up to 0.6m above normal level but can, on occasions, rise by up to
0.9m above normal which causes surface water drainage problems in low lying areas of
Castle Douglas.
The report concludes that the Blackparks station cannot be decommissioned but that
optimisation of the pumps could reduce running costs without presenting an additional
risk of peak water level in Carlingwark Loch.
3.2 SCOTTISH POWER BLACKPARKS FACILITY REPORT (REV 2)
This report, compiled by MWH, updates and expands the findings of the above, earlier,
report, including the installation and analysis of a number of long term water level
monitors.
The report basis was the analysis of the automatic level monitors coupled with hourly
water level data from the Glenlochar gauging station immediately downstream of the
Glenlochar Barrage. Of the five water level monitors two were lost or compromised
during the monitoring period.
The report re-iterates the earlier investigation that the Blackparks Pumping Station and
related protection bunds play an important part in the mitigation of flood risk to the lower
lying areas of Castle Douglas.
It is noted in the report that if the embankments were to breach during a flood event in the
River Dee this would inundate Carlingwark Loch.
The report make a number of recommendations with respect to the upkeep of the water
level monitoring stations and the maintenance of the flood bund associated with the
pumping station. Of the recommendations made it is understood from Scottish Power that,
to date, the flanking bunds have not been raised or maintained and that the level
monitoring points have been shut down. Scottish Power is putting into place meters that
will record the use of the Blackparks pumps in order to allow refinement of its operating
regime.
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3.3 SCOTTISH WATER SOLUTIONS CASTLE DOUGLAS WASTE WATER
TREATMENT WORKS FLOOD RISK ASSESSMENT
As part of the background preparations for the new Castle Douglas wastewater treatment
works (WWTW) Scottish Water Solutions commissioned Mouchel to carry out a flood
risk assessment.
The location of the WWTW is on the south western outskirts of Castle Douglas and,
following concerns raised by SEPA, a flood model was compiled using topographic
information from a digital terrain model (DTM) coupled with survey cross-sections
through the River Dee and Carlingwark Lane. A review within the report of the DTM
information and the topographic survey undertaken at the same time indicates a good
correlation between the two datasets.
Although the flood model includes a survey cross-section through the Blackparks
Pumping facility it appears that this represents the ground level to the east of the bund that
links the pumps to the perimeter of the functional flood plain. The height of the bund is
therefore not known and has been estimated in the model to be 45.00m OD throughout.
The flood model itself entailed a one dimensional assessment of the principal water
courses, resulting in a peak water level for a variety of potential storm event hydrographs.
The function of the Blackparks pumping station was considered within this investigation.
The report indicates the following with respect to recent local flooding;
Some historical flooding was recorded in Castle Douglas, (in the 1995-2007
period) however this was largely related to the blockage of culverts and road
gullies on the other side of the town to the WWTW (i.e. in the south east of the
town). Flood prevention activities noted were largely routine cleaning and
maintenance of culverts, culvert screens and road gullies on the other side of the
town.
…..there have been no fluvial flooding events which have affected properties in
the vicinity of the WWTW in recent years. However agricultural land close to the
Castle Douglas bypass (A75) is flooded up to approximately five times a year.
This is understood to be largely due to the operation of the barrage at
Glenlochar. During extreme rainfall events the barrage is opened to relieve
flooding upstream, resulting in flooding of farmland around Castle Douglas.
The report comments that the Glenlochar Barrage regulates flows to the Tongland Power
Station, and that, in addition, the barrage is raised to alleviate flooding downstream
following high rainfall. The barrage is however also opened if levels upstream are too
high, an action that occurs approximately 5 times a year. A recent case where the barrage
was opened due to extreme flows was in November 2006 when there was flooding in
Dalry and Galloway. At this time the flooding along the River Dee floodplain in the
vicinity of Castle Douglas was considerable but was not observed to overtop the flank
embankments associated with the Blackparks pumping station.
The report identifies that Carlingwark Loch does not drain well due to the flat lying nature
of the valley bottom and due to the water levels in the River Dee being too high to allow
free drainage. The requirement of the Blackparks station is noted to be reduced during the
Summer months indicating that some natural drainage of the Carlingwark Loch to the
River Dee may occur.
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& Scottish Power
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Peak flow analysis of the River Dee and Carlingwark Lane was carried out using the
statistical procedure for the River Dee and the rainfall runoff method for the Carlingwark
Lane.
The report concludes that sizable parts of the low lying areas around the Carlingwark Lane
will be inundated during the design 1 in 200 year storm and that the Blackparks Pumping
Station would be overwhelmed during such an event.
3.4 SCOTTISH POWER GALLOWAY HYDROS CULVENNAN LAND DRAINAGE
PUMPS
The Halcrow Group was commissioned to assess the effects of the Galloway Hydros
Scheme on drainage at Culvennan Farm near the River Dee about 1km downstream of the
Glenlochar Barrage.
This investigation included an assessment of the impact of the hydro scheme on the peak
flow of the River Dee in comparison to the calculated natural flow of the watercourse.
Outputs from this study were combined with a DTM within a 1D steady state hydraulic
model in order to examine the peak water level under a variety of hydrographs for both
before and after the implementation of the hydro scheme.
This report concludes that the hydro scheme increases the average base flow of the River
Dee downstream of Loch Ken by about 6m3/s. The report does however note that the
magnitude of the base flow increase is highly variable due to seasonal and annual
fluctuations.
The flood model adopted by the report indicates that there is an increase in water level
under mean flows in the River Dee with the magnitude of increase reducing with the
increased severity of the flood event.
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4 ADDITIONAL INFORMATION INPUTS
4.1 SCOTTISH POWER
Discussions with Scottish Power were held at Glenlee Power Station. These discussions
confirmed that the pumps at Blackparks are rated at over 40 cubic feet per second and it
was concluded that each pump may be considered to have a capacity of 1.35m3/s. The
pump trigger mechanism at Blackparks is confirmed to be automatic via an electronic
level indicator. A stop alarm has been installed using the available mobile phone network
which is triggered by a pump stoppage or screen blockage. The same mechanism is used
to indicate the pump on / off periods.
4.2 DUMFRIES AND GALLOWAY COUNCIL COUNTRYSIDE RANGER
Discussions were held with the Dumfries and Galloway Council Countryside Ranger, Mr
Keith Kirk. From these discussions an additional understanding of the history of
Carlingwark Loch was reached as well as local historical information and more recent
bathymetry data for the loch.
4.3 NATIONAL TRUST FOR SCOTLAND RANGER SERVICE
Additional discussions with Mr Karl Mundey of the NTS ranger service were carried out
providing information concerning the general habitat of the Carlingwark Lane area, plant
growth along the Lane and the nature and effectiveness of the Scottish Power pumping
stations in the area.
4.4 DUMFRIES AND GALLOWAY LIBRARIES
Background historical data for the Castle Douglas areas was available from the local
library in Castle Douglas.
4.5 ADDITIONAL INFORMATION
A significant local flooding event occurred on Loch Ken in both November 2010 and
December 1978 when the level of the Loch was noted to be at the floor level of Parton
Village Hall. A recent topographic survey establishes the peak water level during these
two events to be 47.2m OD. It is understood that a similar storm event occurred in 1909
prior to the construction of the hydro scheme.
The bathymetric survey of Loch Ken carried out in 1903 suggests that a substantial part of
Loch Ken already existed at that time. This survey also suggests that the River Dee
outflow bed level from Loch Ken at Glenlochar effectively dictates the natural upstream
water level of the loch.
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5 FLOOD RISK ASSESSMENT
5.1 MODEL SETUP
General
The modelling of the River Dee/Carlingwark Lane watercourse system is relative to the
key features identified by the Council and during the site walkover, and by the review of
the available maps and surveys. For the purpose of this report particular attention is given
to the area between the confluence of the Carlingwark Lane and River Dee and the
Gelston Burn upstream of the Carlingwark Loch.
The full model of the system covers approximately 3.76km of the River Dee and about
2.1km of the Carlingwark Lane. An additional 2km of the Gelston Burn was added to the
model together with a 1.1km portion of the Threave Castle Island eastern spur. The reach
of watercourse modelled was to obtain an approximate parity with the earlier Mouchel 1D
model and established to be long enough to avoid any adverse affects on the water flow
from any significant features within the channel. Water storage upstream of the
Carlingwark Loch was also a consideration in the design of the model facilitated by an
extension to the Gelston Burn reach. The number of cross sections utilised in the model is
in relation to areas of restriction in flow and to construct a suitably representative analysis.
In this respect the cross sections mimicked those undertaken be Mouchel, using the same
topographic information. Additional cross sections were added in order to improve the
model at selected points.
For the purpose of this Flood Risk Assessment the Mike 11 software has been utilised in
conjunction with Mike21 and the MikeFLOOD software to produce a fully dynamic 2
Dimensional Model, that models the effects of flood plain storage and overland flow. As
the open channel flow software Mike11 provides the basic backbone to the model, all
cross sections within Mike11 have been adapted and incorporated in the model to provide
an accurate representation of the channel width and form. The Mike 21 entails the use of a
‘bathymetry’ file which is based on the available Digital Terrain Model (DTM) dataset. At
the point of overtopping the water in the model transfers from the Mike11 channel into the
Mike21 bathymetry where it may spread out in 2 dimensions by cell to cell transfer. The
1D and 2D integration comprises a dynamic link based on flow and momentum.
Model Survey Inputs
Topographic information obtained for the Mouchel flood model comprised a series of
cross sections through the Carlingwark Lane and River Dee and was utilised in this
assessment as discussed with the Council.
Bridges and culverts relating to the watercourses were compiled either using data from the
Mouchel report or, where applicable, by discussions with Scottish Power or measurements
undertaken by Terrenus during the site walkover inspection. Additional topographic
information was provided by the Council for the lower lying parts of Castle Douglas,
particularly the area adjacent to the Carlingwark Loch. This survey information took the
form of spot height data and was used to amend the Lidar ground surface elevations in the
‘bathymetry’ layer of the 2D model.
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Where variations in elevations were identified the grid cell was amended to conform to the
available survey information. It is noted that the variation between the survey information
and the Lidar data set in the southern part of Castle Douglas is modest and generally less
than 300mm. The topographic survey data is included in the appendix to this report.
This information was combined with the survey information and digital terrain data
obtained from SEPA via Dumfries and Galloway Council to provide as accurate an overall
representation of the river profile as possible.
The, or ground surface elevation model, was created using SEPA sourced Lidar data. This
provided height information consisting of Digital Terrain (bald Earth) Model (DTM) at
5m posting intervals. It is understood that the height data was created from the aerial
photography which was captured with a 60% overlap between frames using Photo-
Grammetric techniques. The resulting data is highly accurate when compared to other
existing datasets, typically having a vertical accuracy of +/- 50cm RMSE.
It is confirmed that the 1D element of the model is based solely on the available
topographic survey information via the Mouchel 1D model. The 2D element of the model
is based on the above DTM information as amended in the southern part of Castle
Douglas using the additional available survey information from the Council. Where
amended the DTM was adjusted to the more accurate topographic survey information and
consideration given to the impact of such adjustments on adjacent cells.
With respect to larger water bodies SEPA made the following comment:
.... conventional LiDAR pulses may not be returned from waterbodies and will
not provide suitable penetration to capture bathymetry. This means that the
accuracy of such areas is lower in comparison to dry areas. Returns from the
LiDAR sensor may be received from the water surface - giving a representation
of the water surface in the DTM. However, in many cases there may be no
returns from a water surface, leading to gaps in the dataset which are sometimes
infilled by interpolation.
The pre-storm surface water level of the key Carlingwark Loch water body was
established to be 43.5m OD using local knowledge and the detailed topographic data
throughout the low lying area of Castle Douglas. In addition the Lidar data was adapted in
certain other key areas including the loch side area of Castle Douglas and the A75 based
on the known topography and information established from the Council provided survey
data.
Additional small inflows from field drainage ditches were noted along the line of the
Carlingwark Lane. The general topography of these features was picked up as part of the
DTM data for the area.
In order to keep the model manageable yet representative of important and significant land
features (such as the A75 road embankment) a map grid of 10m was adopted for the flood
model. Minor corrections were imposed on the model where the DTM was considered to
include possible height errors.
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Downstream River Dee Boundary and initial Model Conditions
The location of the downstream boundary corresponds with the final 1D cross section on
the River Dee. In this case the boundary has been placed sufficiently far downstream to be
remote from the Carlingwark Lane and any structures in the vicinity. The downstream
boundary conditions for the site have been set in hydrodynamic mode with an open
boundary. The Hydrodynamic (HD) Module has been applied to the boundary and is
defined by the Time series (TS). The Q-h relationship at the downstream boundary is
computed using a Manning’s value of 0.045 and a slope of 0.002.
The 1D element of the model is set with an initial 0.5m water in the river channel system
prior to the commencement of the storm hydrograph.
The initial conditions for the 2D element of the model are dry at the commencement of
the storm hydrograph. The flood plain inundation is set to hydrodynamic only with a
drying depth of 0.01m and a flooding depth of 0.02m.
Structures
An important feature with all structures when modelling with MIKE11and MikeFLOOD
is that they must impose a constriction to the flow. That is, an inlet and an outlet loss must
be present over the structure and the structure’s geometry definition (with respect to flow-
area) must be smaller than both the up and downstream cross sections for all levels
defined in the structure.
Features such as the A75 embankment, the bridge over the Carlingwark Lane and the
outfall from the Carlingwark Loch via the Buchan Bridge have been picked up by the
DTM and input to the flood model.
Details of the Blackparks Pumping station, the pumping rates and associated non-return
culverts were established from previous reports, discussions with Scottish Power and the
site walk-over. The model assumes that the pumps will stop working when the peak water
level rises to 46m OD (i.e. above the existing pump bund).
River Banks and Model Domain / Active Area
The 2D active model area is shown on Figure 5 in the Appendix and extendes throughout
the lower lying flood plain area of the River Dee from north of the Glenlochar Barrage to
approximately the Lodge of Kelton downstream of Threave Island. The 2D element of the
model also includes the flood plain of the Black Bridge Burn to the west of the River Dee
and the entire Carlingwark Lane, Carlingwark Loch and Gelston Burn tributary system.
Figure 5 also indicates the blocked cells along the principal water courses (River Dee,
Gelston Burn and Carlingwark Lane), where the 1D elment of the model defines the water
flow and peak water level.
As noted above the 1D and 2D integrated model comprises a dynamic link based on flow
and momentum. This link relies on the 1D cross-sectional data to initiate flooding in the
2D element of the model and hence is based on topographic survey information provided
with the Mouchel 1D model data set.
Additional ground truthing has not been carried out for the DTM dataset however, as
noted above, the variation between the survey information in the south of Castle Douglas
and the Lidar data set is generally less than 300mm.Additional Notes
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For ease of reporting and consideration the model outputs in this report represent fixed
data from each model run. Full model outputs including shape files are presented
separately in electronic format.
The model outputs within this report, unless otherwise recorded, represent the peak water
level during related return period model design. As such the output drawings show the
extreme water levels throughout the entire storm hydrograph and not a particular moment
during the storm period. Likewise, the data provided in the model output tables represents
the peak water level at selected points.
The nominal simulation period in all model runs covers the combined Dee / Gelston peak
flood hydrographs during a 41 hour period. The computational time step for all model
runs is 4 seconds resulting in 36900 time steps for the full model run.
5.2 RIVER FLOW
Although some gauging station data is available from the Glenlochar Barrage the quality
of this data is limited by the workings of the hydro-power facilities and the station itself.
With respect to the design 1 in 200 year storm event, rainfall records and catchment
descriptors have been obtained from the Flood Estimation Handbook (FEH) with flow
rates calculated using the following methodologies.
FEH (2007) QMED (Index Flood) calculation;
Improved FEH estimate of QMED (2008);
Mean Annual Flow (MAF) using Institute of Hydrology Research paper
124 (for comparison);
Statistical analysis as provide by SEPA;
Statistical analysis as undertaken by Mouchel;
Rainfall Runoff Method as undertaken by Mouchel; and,
FEH Rainfall Runoff method.
An analysis of these methods was discussed with SEPA and the Mouchel statistical
method found to be reasonable. This resulted in a peak flow for the design storm of
495m3/s.
Peak flows for other storm events were, in agreement with the Council, adopted from the
Mouchel flood risk assessment.
A summary of the possible peak design flows for the watercourse is provided in Table 1 in
the Appendix.
The current Scottish Executive guidance ‘UKCIP02 Update (2003)’ suggests that peak
river flows may increase by between 15% and 20% in the south-west of Scotland by the
mid 2080’s due to global climate change. In line with SEPA recommendations and
following discussions with the Council an additional allowance of 20% has been added to
the peak flow over and above the estimated 1 in 200 year probability flood event. This
increase brings the peak flow for the River Dee and Carlingwark Lane to approximately
594m3/s and 43m3/s respectively.
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The catchment of the River Dee is some 810km2 to the Glenlochar Barrage and 864km2
to the Bridge of Dee. The Carlingwark Lane including the Gelston Burn adds some
13.8km2 upstream of the Bridge of Dee. The likelihood of an extreme storm occurrence
throughout the entire Dee catchment is low and, due to the differing sizes of the Dee and
Carlingwark catchments, the time to peak is likely to occur at differing times. In this
assessment separate flood hydrographs have been compiled for the Dee and Carlingwark
catchments. For the design 1 in 200 year storm event the time to peak of the Dee is about
18 hours after the commencement of the storm. For the same event the time to peak of the
Carlingwark is 12 hours after the start of the storm and hence some 6 hours prior to the
peak of the River Dee.
This variation in peak flow is considered to offer a reasonable worst case scenario for the
local area. Additional model runs were carried out to investigate the impact of differing
storm events on the Carlingwark Loch and are provided as model outputs in the appendix.
5.3 MODEL RESULTS UNDER EXISTING GROUND CONDITIONS
Using standard hydrodynamic software modelling techniques for open channel flow,
information between cross sections is interpolated through the Mike 11 software and the
river flood levels calculated accordingly. Integration of this data with Mike21 through
dynamic linkages and the MikeFLOOD software via cell to cell transfer produces a 2
Dimensional Model, which models the effects of flood plain storage and overland flow.
Uncertainties remain regarding the channel roughness that affects the relationship between
flow rate and water level. The analysis must, therefore, be regarded as approximate.
In order to fully analyse the watercourse, runs were carried out at a variety of flow
volumes as discussed below. The Manning roughness ‘n’ numbers used in the model were
in line with those adopted in the 1D Mouchel model, varying between 0.04 and 0.045 for
the watercourse channels. The flood plain was assigned a global Manning roughness
factor of 0.045. Sensitivity analysis was carried out on the 1D element of the model as
used in the 2D model where the channels were adapted to dynamic linkage. Small
variations in Manning ‘n’ value were found to have only a modest impact on the 1D
model results.
The results of the MikeFLOOD output are shown on the drawings contained within the
appendix to this report. It should be borne in mind that the actual movement of water
throughout the flood plain is affected by the timing of the storm events, a fact that is
displayed in the additional electronic submission. The drawings provided in the appendix
show peak levels around Castle Douglas for simple clarity.
The area of the Carlingwark Loch is included in the model with the radar data and a
review of both local knowledge and the detailed survey data supplied by the Council used
to provide the standing water level (43.5mOD) into which the storm hydrograph flows.
Peak water levels for the Carlingwark Loch in the vicinity of the Isle of Whitepark (in the
north of the loch) are provided in Table 3 in the appendix. Table 3 also provides details of
the various mitigation measures considered and their impacts on the Carlingwark Loch.
Under existing ground and pump operating conditions the model indicates that the
function of the upper Carlingwark Lane, Carlingwark Loch and Gelston Burn represents
poorly drained land. The level of Carlingwark Loch thus rises as the local storm event
progresses and remains high during the entire period of the Dee catchment storm period.
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These results indicate that the Blackparks Pumps represent a very small portion of the
peak flow within the Carlingwark Lane and become ineffective at any significant return
period (1 in 2 years and above). The chief effect of the pumps is therefore at the more
modest average flows within the Dee-Carlingwark system.
Notwithstanding the above it is clear that under existing ground conditions and at
relatively modest flows the pumps improve the overall drainage of the area and thus may
be seen to assist the general agricultural assets in the local area. In addition the pumps
may be seen to provide increased potential water storage of the Carlingwark Loch and
upper Gelston Burn at the commencement of a peak storm event. Nevertheless the pumps
are not seen to mitigate the overall risk of flooding during an extreme storm event.
The DTM indicates that the lower lying areas of Castle Douglas at the northern end of the
Carlingwark Loch are at between about 44m OD and 45m OD. Detailed surveying carried
out by the Council indicates that the near Loch area of the town (around Lochside Park)
the existing levels are between 43.9m OD and 44.5m OD. Ordnance Survey spot heights
and detailed survey information along Marl Street and Queen Street to the north and King
Street to the west of the Loch range between 47m OD and about 45m OD on Queen
Street. The land falls gently from these streets towards the Carlingwark Loch. Storm
events in excess of 1 in 25 years will inundate parts of the near loch area within Castle
Douglas. The risk to Queen Street and associated areas during such events will chiefly be
dependent on the initial level of the loch. It is likely that the initial loch conditions will
result in parts of the park area, loch bank and caravan park being at risk of inundation
during lesser storm events.
It should in addition be noted that the local drainage known to discharge into the
Carlingwark Loch is likely to back up during such events and that the Loch is known to
respond early in the local hydrograph.
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6 DISCUSSION AND RECOMMENDATIONS
6.1 FINDINGS UNDER EXISTING CONDITIONS
The model runs allow a number of overall conclusions to be made;
Increasing storm severity (from the 1 in 2 year event to the 1 in 200 year event)
results in a steady increase in water levels through the Carlingwark area;
The Carlingwark Loch water level rises early in the storm hydrograph and tends to
be sustained thereafter, suggesting that the constriction of the channel below the
Buchan Bridge and the very flat fall of the Carlingwark Lane itself limits outflow
from the loch at the peak of the hydrograph;
The peak water level near the Isle of Whitepark (Lochside Park) varies from
44.63m OD during the 1 in 2 year event to 44.98m OD during the 1 in 200 year
event. In reality due to possible vegetation growth around Buchan Bridge and local
storm drainage from Castle Douglas itself the latter conditions are likely to
inundate some parts and environs of Queen Street.
The impact of the Blackpark Pumps on the drainage of the Carlingwark Lane
during an extreme storm event is negligible; however the pumps do have an
impact in regulating local agricultural water levels during normal flow conditions
between the pump facilities and Castle Douglas.
6.2 BLACKPARK PUMP FACILITY
The Scottish Power report 41515757 – Rev2 dated April 2009 on the Blackparks Pumps
indicates the following:
It is clear that the Blackpark pumping station plays an essential role in allowing
a reasonably efficient discharge from Carlingwark Loch below Buchan Bridge,
and therefore alleviating the risk of inundation to the urban spread of Castle
Douglas. Equally the flank embankments that complete the Blackpark facility
must remain intact in order to alleviate the risk of inundation to the urban
spread of Castle Douglas.
The current assessment broadly agrees with the above statement concerning the flank
embankments but notes that the pumps become less significant during significant storm
events. During a more isolated storm event the pumps may result in an increased capacity
within the Carlingwark Loch system to attenuate the peak storm flow and thus reduce the
risk of flooding to Castle Douglas however such an effect is negligible in the current
model.
It is concluded that the pumps do provide an agricultural advantage in the local area (as
they were originally designed to do) but that they provide no significant mitigation to the
risk of flooding in the Castle Douglas area during the design 1 in 200 year storm event.
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6.3 POSSIBLE MITIGATION MEASURES
Following discussions with the Council consideration has been given to possible flood
mitigation measures which would reduce the risk of flooding to Castle Douglas whilst
retaining the overall aesthetic and environmental well-being of the local area. Passive
measures were preferred when considering appropriate mitigation measures.
Such measures include the following;
1. Improvement and raising of the Blackpark flank embankments (bunds) to 45.45m
OD;
2. Provision of upstream control measures on the Gelston Burn to attenuate storm
water inflow to the Carlingwark Loch thus allowing a longer period for the loch to
drain during the design storm event;
3. Provision of the Gelston Burn control measures coupled with additional
downstream control at the A75.
The location of the above possible control measures is shown on Figure 2 in the
Appendix.
The Gelston Burn control comprises a simple flap valve non-return culvert with flank
embankments at a crest level of 45.5m OD. Two differing culverts were modelled at this
location; the first being a box culvert measuring 3m width by 1m high. Such a culvert
would allow some 10m3/s to pass when full but with no upstream head. The second
culvert comprised a circular pipe 0.9m in diameter which would have a capacity of about
2.5m3/s when full with no upstream head.
The measures modelled at the A75 comprised a 5m wide by 1m high non-return gate
which did not affect the downstream water flow but did prevent flow from the River Dee
to the Carlingwark Loch. In this case the road embankment provides suitable flank
embankments.
The peak water level around the Isle of Whitepark during the model runs employing these
mitigation measures are provided in Table 3 in the Appendix.
Raising of the Blackpark Flank Embankments
It is noted that raising the flank embankments at the Blackpark Pumps results in a small
increase in peak water level in the Carlingwark Loch during the 1 in 2 year return period
and a slight decrease during the 1 in 50 year storm. It is likely that this effect is due to the
early time to concentration of the Gelston Burn catchment initially filling up the area
upstream of the pumps. Thereafter the water in this area is unable to exit due to the
increasing water levels arising from the River Dee.
Gelston Burn Control Measures
The use of the larger box culvert in the upstream Gelston Burn control does not provide
any significant attenuation of the catchment runoff and the peak water levels are found to
increase slightly in the Carlingwark Loch.
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Using a reduced culvert size significantly restricts the storm flow of the Gelston Burn and
results in the attenuation of storm water over the lower part of the Gelston Burn valley
floor. The peak water levels upstream of the control measures during the 1 in 2 year storm
are in the order of 44.79m OD rising to 45.36m OD for the 1 in 50 year event.
The impact of this attenuation is to lower the peak water level of the loch by about 110mm
during the 1 in 2 year event and raise it by some 640mm during the 1 in 50 year event.
The rise in peak water level during the 1 in 100 year event is 170mm suggesting an impact
during the more extreme storm events.
Additional A75 Control Measures
Applying control measures at the A75 allows the water immediately upstream of the A75
to drain during the early part of the storm event, however, the peak water level within the
Carlingwark Loch remains unchanged during the 1 in 2 year event when compared with
the Gelston Burn control only and shows only a modest fall during the 1 in 50 year event.
6.4 GENERAL CONCLUSIONS ON POSSIBLE MITIGATION MEASURES
The flow of water around Castle Douglas during peak storm events is complex entailing
overall poor drainage, differing times to peak flow, the presence of the Blackpark Pumps
and the variable nature of the peak flow in the River Dee due to the hydro power scheme.
Whilst the Blackpark embankments do work in tandem with the pumps themselves,
raising these features does not in itself reduce the risk of flooding at Castle Douglas.
Passive mitigation measures have been modelled but fail to provide a definitive course of
action that will reduce the risk of flooding to Castle Douglas during all storm events.
Whilst the Gelston Burn control measures do provide upstream attenuation the model
indicates that the flow from the Carlingwark Loch is restricted through the Carlingwark
Lane in the vicinity of Buchan Bridge. Such an effect is shown when comparing the
Gelston control measures with the additional A75 control where the area between the A75
and the loch drains early in the peak storm event but the loch itself does not. Any use of
the Gelston Burn for attenuation purposes would therefore have to be coupled with an
improvement of the flow of water from the loch to the area upstream of the A75.
6.5 OUTLINE RECOMMENDATIONS
The model outputs suggest that the Blackpark Pumps greatest effectiveness is on a normal
day to day basis where the water levels upstream of the pumps is kept low thus normal
field operations are maintained. Such an action formed part of the original purpose of the
pumps and should be maintained if possible, however it should be recognised that the
pumps themselves do not provide any significant flood mitigation to the Castle Douglas
area.
Passive water control and flood risk methods on the Gelston Burn and A75 could be
implemented with the existing Blackpark Pumps in place and could result in a stabilisation
of the peak level in the Carlingwark Loch should the flow of water from the loch be
improved. Additional modelling would be required to confirm this.
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oo000oo
Terrenus CDH Ltd wishes to thank Dumfries and Galloway Council and Scottish Power
for the opportunity to prepare this report. We trust that the report meets with your
requirements at this stage. However, should you wish to discuss the contents of the report
then please contact the undersigned.
Signed for and on behalf of
Terrenus CDH Ltd
W. Hume S. Curran
Director Director
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
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APPENDICES
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
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FIGURES & DRAWINGS
©Crown copyright. All rights reserved. Licence No. AL100035646
Client:
Dumfries & Galloway Council
Drawing Title:
Site Location Plan
1 Orbital Court
Peel Park East Kilbride, G74 5PH
Tel: 01355 279 000 Fax: 01355 263 629
Project:
Castle Douglas
Flood Risk Assessment
Date:
24-03-12
Figure 1 Grid Ref: NX 7470 6234
SCALE: N.T.S. DO NOT SCALE
Client:
Dumfries & Galloway Council
Drawing Title:
Detail of Carlingwark Lane 1 Orbital Court
Peel Park
East Kilbride, G74 5PH
Tel: 01355 279 000 Fax: 01355 263 629
Project:
Castle Douglas Flood Risk Assessment
Date: 24-03-12
Figure 2 Grid Ref: NX 7470 6234
SCALE: N.T.S. DO NOT SCALE
Blackpark Pumping Station
Blackpark Flank Bunds
River Dee
Castle Douglas
Sewerage Station
Local Drainage Channels
Possible Gelston Burn
Control Measures.
Possible A75 Control
Measures.
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Cross Sections Location
Date
20th June 2013
Dwng No.3
Figure 3a
Chainage 0
Chainage 470
Chainage 1000
Chainage 1800
Chainage 2300 Chainage 2450
Chainage 2300
Chainage 1100
Chainage 626
Chainage 508
Chainage 362
Chainage 350
Chainage 120
Chainage 0
Chainage 0
Chainage 10
Chainage 73
Chainage 85
Chainage 514
Chainage 942
Chainage 1365
Chainage 1788
Chainage 2236
Chainage 3760
Chainage 3455
Chainage 2875
Chainage 2497
RIVER DEE
THREAVE EAST SPUR
LOCH
Chainage 3086
Chainage 670
Client:
Dumfries & Galloway Council
Drawing Title:
Carlingwark Lane Cross-Sections 1 Orbital Court
Peel Park
East Kilbride, G74 5PH
Tel: 01355 279 000 Fax: 01355 263 629
Project:
Castle Douglas Flood Risk Assessment
Date: 20-06-13
Figure 3b Grid Ref: NX 7470 6234
SCALE: N.T.S. DO NOT SCALE
Chainage 0
Chainage 118.42
Chainage 261.82
Chainage 415.03
Chainage 496.12
Chainage 640.13
Chainage 897.17
Chainage 983.95
Chainage 1056.04
Chainage 1215.12
Chainage 1420.97
Chainage 1640.16
Chainage 1662.04
Chainage 1846.66 Chainage 2048.23
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
0
24
.59
39
.49
59
.14
83
.86
10
7.4
12
8.1
4
13
9.3
4
16
0.6
16
8.3
1
17
4.6
2
18
0.4
28
0.4
6
28
2.0
2
29
5.1
32
0.4
3
32
4
32
8.6
2
34
2.3
1
36
6.2
7
38
2.0
7
40
3.3
7
42
4.4
7
Cross section 0
0
10
20
30
40
50
60
0
43
.53
74
.46
91
.5
11
0.8
5
14
5.0
2
15
8.6
16
1.4
3
16
5.3
6
26
3.2
7
26
4.7
4
26
5.5
5
27
6.0
1
28
0.7
4
28
5.2
4
30
0.1
5
30
5.4
9
30
9.8
9
34
8.4
8
36
8.1
8
38
9.8
5
41
0.3
Cross section 10.27
0
10
20
30
40
50
60
0
17
.3
50
.15
11
9.1
3
13
4.4
1
13
7.8
5
15
1.0
8
17
3.5
1
18
8.8
5
19
7.2
1
21
3.0
3
22
7.7
2
23
5.9
5
25
6.2
3
28
5.6
1
30
0.6
6
34
0.8
4
37
1.6
9
39
4.2
2
40
0.0
5
43
9.9
7
Cross section 73.73
0
10
20
30
40
50
60
0
66
.53
85
.62
10
9.2
8
12
0.9
8
12
7.8
7
13
9.9
15
4.9
16
9.8
3
18
4.8
7
20
2.6
1
21
4.6
6
22
0.6
3
22
4.4
1
23
3.8
3
24
7.0
6
26
8.1
2
27
5.0
6
31
8.6
34
3.8
1
36
6.2
6
36
8.1
8
37
0.0
5
37
6.8
3
39
8.2
2
41
8.4
8
Cross section 85.74
River Dee
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
-60
62
.15
9
13
5.1
85
22
0.6
15
23
8.2
94
27
4.2
99
33
8.6
16
37
9.8
06
40
8.9
02
42
1.3
54
44
6.9
17
47
6.1
25
50
8.7
67
51
5.6
88
54
2.3
4
56
9.6
78
60
2.9
73
64
5.1
72
66
1.4
03
73
8.3
83
84
0.5
96
85
0.9
6
88
6.4
45
94
4.1
12
Cross section 514.29
0
10
20
30
40
50
60
70
-12
0
35
.18
14
2.3
2
22
0.3
8
36
9.3
6
39
7.3
5
40
1.1
3
51
8.0
8
57
5.1
4
64
6.9
7
69
5.3
6
70
3.7
4
72
5.6
9
76
7.9
7
79
9.7
1
82
1.4
8
82
8.1
6
90
2.2
1
95
3.2
9
10
18
.03
10
42
.93
11
12
.66
13
17
.84
13
88
.18
14
76
.65
Cross section 942.84
0
10
20
30
40
50
60
-11
4.1
5
75
.27
9
14
4.4
45
23
6.3
54
35
1.7
95
38
7.5
67
49
3.3
99
54
7.7
28
64
3.5
15
66
4.4
34
71
1.6
37
77
0.4
2
84
6.7
28
89
3.0
21
10
67
.93
2
11
68
.80
5
12
64
.19
3
13
87
.05
14
70
.46
2
15
73
.36
3
16
35
.94
4
18
04
.78
1
Cross section 1365.48
0
10
20
30
40
50
60
70
-10
8.3
71
.61
14
7.6
1
22
4.5
9
32
6.6
1
42
5.1
50
1.0
8
56
9.6
1
62
3.2
8
64
6.5
4
73
1.4
8
86
2.1
5
92
6.5
4
12
44
.54
13
40
.37
15
44
.68
16
40
.02
17
29
.29
18
32
.07
19
08
.15
19
56
.94
23
38
.25
Cross section 1365.48
River Dee
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
0
87
.02
17
2.2
9
24
9.1
9
45
8.9
6
48
7.6
2
58
9.9
6
63
6.7
71
8.5
4
79
1.1
7
82
2.1
9
92
1.4
10
18
.45
10
74
.05
11
50
.68
12
44
.13
13
43
.92
17
74
.13
19
39
.1
21
22
.99
21
64
.03
24
21
.4
25
33
.84
26
40
.05
28
25
.27
Cross section 2236.26
0
10
20
30
40
50
60
-24
2.2
37
-22
5.2
81
-20
8.3
24
-19
1.3
67
-17
4.4
11
-15
7.4
54
-14
0.4
98
-12
3.5
41
-10
6.5
84
-89
.62
8
-72
.67
1
-55
.71
5
-38
.75
8
-21
.80
1
-4.8
45
39
2.6
6
62
0.6
6
76
6.4
7
10
39
.35
11
37
.55
12
09
.02
14
53
.39
16
14
.95
17
60
.24
22
24
.06
27
02
.5
29
77
.7
Cross section 2497.11
0
10
20
30
40
50
60
0
72
.18
11
4.0
5
13
7.4
1
17
4.5
24
2.4
1
31
1.8
3
38
5.7
44
2.4
8
50
3.9
3
57
6.0
4
63
3.3
1
70
8.3
9
82
6.4
9
83
0.2
2
87
9.6
4
94
0.5
6
99
8.6
3
10
22
.8
10
57
.89
14
35
.8
15
00
.17
17
55
.98
18
12
.02
Cross section 2875.51
0
10
20
30
40
50
60
0
35
.06
97
.5
18
7.7
9
26
8.8
9
34
0.8
8
42
6.6
7
50
4.2
57
9.9
6
71
3.2
6
86
1.9
2
92
6.4
7
10
21
.33
10
86
.44
11
67
.14
12
45
.32
13
18
.46
13
38
.12
14
18
.87
18
23
.83
19
01
.05
20
07
.74
20
82
.92
21
63
.49
Cross section 3086.41
River Dee
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
0
30
56
.52
91
.75
12
5.3
16
3.6
3
20
2.7
7
23
5.8
1
28
3.6
9
32
4.3
3
35
4.3
7
36
0.6
7
37
3.3
2
39
7.7
3
42
0.2
2
43
6.6
6
46
5.1
1
48
7.1
1
Cross section 3455
0
10
20
30
40
50
60
0
62
.11
13
8.2
2
22
3.7
2
27
5.9
4
32
6.9
1
38
3.1
5
47
8.2
49
5.6
9
53
6.6
3
58
2.9
4
68
0.4
8
78
8.2
87
8.5
3
96
2.1
4
10
45
.83
11
70
.25
12
55
.76
13
52
.3
14
03
.23
14
99
.42
15
66
.59
16
11
.63
16
71
.02
17
39
.15
18
08
.17
18
70
.4
Cross section 3760
River Dee
34
35
36
37
38
39
40
41
42
43
44
0 10.27 73.73 85.74 514.29 942.84 1365.48 1788.11 2236.26 2497.11 2875.51 3086.41 3455 3760
Long section
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
5
10
15
20
25
30
35
40
45
50
-93
8.6
26
-85
4.1
49
-76
9.6
73
-68
5.1
97
-60
0.7
2
-51
6.2
44
-43
1.7
68
-34
7.2
91
-26
2.8
15
-17
8.3
39
-93
.86
3
-9.3
86
41
.82
4
88
.87
7
13
5.9
29
18
2.9
81
24
6.3
85
31
6.4
61
36
0.7
34
40
7.7
87
45
4.8
39
50
1.8
91
Cross section 0
0
10
20
30
40
50
60
-88
9.8
7
-82
7.5
79
-7
65
.28
8
-70
2.9
97
-6
40
.70
6
-57
8.4
15
-5
16
.12
4
-45
3.8
34
-3
91
.54
3
-32
9.2
52
-2
66
.96
1
-20
4.6
7
-14
2.3
79
-8
0.0
88
-1
7.7
97
2
7.7
79
6
6.6
7
10
5.5
6
14
4.4
51
1
83
.34
2
22
2.2
32
2
61
.12
3
31
1.6
02
3
61
.99
5
40
4.9
11
4
44
.46
4
48
3.3
55
5
22
.24
5
Cross section 350
0
10
20
30
40
50
60 Cross section 362.91
0
10
20
30
40
50
60
0
13
.79
29
.07
48
.26
61
.2
82
.28
10
4.1
1
12
4.9
9
14
4.5
7
16
5.0
2
18
3.4
8
19
1.0
5
19
3.0
9
19
6.7
6
19
8.3
20
7.1
5
21
0.9
7
22
5.6
8
24
2.3
6
25
5.1
4
26
8.7
27
8.3
4
27
9.5
2
28
7.9
8
30
6.2
8
32
5.9
7
34
6.3
4
Cross section 508.18
River Dee (Threave East Spur)
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
0
30
56
.52
91
.75
12
5.3
16
3.6
3
20
2.7
7
23
5.8
1
28
3.6
9
32
4.3
3
35
4.3
7
36
0.6
7
37
3.3
2
39
7.7
3
42
0.2
2
43
6.6
6
46
5.1
1
48
7.1
1
Cross section 626.20
0
10
20
30
40
50
60
Cross section 1100
River Dee (Threave East Spur)
37
38
39
40
41
42
43
0 120 350 362.91 508.18 626.2 1110
Long section
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
40
41
42
43
44
45
46
47
0 19.48 40.83 51.36 54.12 56.14 58.23 59.95 67.91 86.6 98.96
Cross section 0
0
10
20
30
40
50
60
0
6.2
13
.3
15
.7
18
.2
26
.3
27
.3
28
.3
29
.6
35
39
.5
53
71
.4
91
.9
11
0.5
12
8.9
13
8.4
15
7.4
16
2.2
16
4.6
17
6.4
20
0.3
Cross section 118.42
0
10
20
30
40
50
60
0
34
.86
91
.45
10
9.4
1
18
4.1
1
22
5.3
1
28
7.9
2
36
5.3
2
45
0.0
1
53
6.7
2
61
0.8
1
68
0.6
9
74
3.4
9
76
2.8
9
76
8.7
9
82
5.4
86
4.6
3
90
6.4
94
2.3
1
97
5.8
3
10
14
.02
10
54
.14
10
84
.17
11
35
.61
11
89
.79
Cross section 415.03
0
10
20
30
40
50
60
0
21
.77
68
.21
11
9.7
4
12
3.5
3
16
6.3
4
21
7.6
3
28
4.8
33
3.8
9
39
5.8
7
42
8.3
45
5.4
5
46
0.6
2
52
5.5
4
56
8.8
6
61
9.8
2
67
3.9
3
72
3.8
3
75
1.9
1
Cross section 261.82
Carlingwark Lane
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
38
40
42
44
46
48
50
0
12
5.5
6
22
5.8
3
35
8.5
2
49
1.8
6
60
3.3
3
68
6.8
4
84
3.1
6
99
9.6
5
10
92
.74
1
11
10
.26
8
11
27
.79
5
11
45
.32
1
11
62
.84
8
11
80
.37
4
11
97
.90
1
12
15
.42
7
12
32
.95
4
12
50
.48
1
12
68
.00
7
12
85
.53
4
13
03
.06
1
13
20
.58
7
Cross section 496.12
0
10
20
30
40
50
60
70
0
13
3.3
9
22
5.9
7
40
9.4
3
51
0.6
8
61
4.2
6
68
6.2
1
69
6.6
57
70
6.1
65
71
5.6
73
72
5.1
82
73
4.6
9
74
4.1
99
75
3.7
07
76
3.2
16
77
2.7
24
78
2.2
32
79
1.7
41
80
1.2
49
81
0.7
57
82
0.2
66
82
9.7
74
83
9.2
83
84
8.7
91
85
8.2
99
86
7.8
08
87
7.3
16
Cross section 640.13
0
10
20
30
40
50
60
-55
2
4.9
5
64
.8
11
5.5
4
16
8.2
3
23
0.9
8
27
4.6
1
31
6.5
7
36
2.2
8
40
6.4
4
30
.9
43
7.8
5
02
.48
5
44
.72
5
51
.98
6
05
.69
6
68
.44
7
04
.6
72
5.3
9
75
6.7
2
80
2.3
7
85
3.7
9
00
.54
9
47
.28
9
68
.17
Cross section 897.17
0
10
20
30
40
50
60
0
12
9.6
25
6.1
38
1.3
46
9.7
59
2.9
9
68
5.9
5
73
8.8
7
84
5.0
9
93
2.5
7
10
56
.41
11
22
.68
8
11
88
.96
7
12
55
.24
5
13
21
.52
4
13
87
.80
2
14
54
.08
15
20
.35
9
15
86
.63
7
16
52
.91
6
17
19
.19
4
17
85
.47
2
18
51
.75
1
19
18
.02
9
19
84
.30
7
Cross section 983.95
Carlingwark Lane
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
0
13
5.3
7
28
0.5
6
39
3.8
4
48
6.0
1
55
7.1
5
69
8.2
2
82
6.5
5
91
5.9
85
96
0.5
58
10
05
.13
2
10
49
.70
5
10
94
.27
8
11
38
.85
1
11
83
.42
4
12
27
.99
7
12
72
.57
13
17
.14
3
13
61
.71
6
14
06
.28
9
14
50
.86
3
14
95
.43
6
15
40
.00
9
15
84
.58
2
16
29
.15
5
Cross section 1056.04
38
40
42
44
46
48
50
52
Cross section 1215.12
0
10
20
30
40
50
60
0
61
.7
12
9.9
19
0.1
27
4.6
35
1.1
41
4.2
48
0
55
2.0
2
56
6.1
1
57
5.0
6
59
2.1
5
67
0.9
2
73
0.0
1
81
2.5
8
89
1.5
8
97
1.5
10
42
.57
Cross section 1420.97
0
10
20
30
40
50
60
Cross section 1644.16
Carlingwark Lane
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
0
10
20
30
40
50
60
Cross section 1662.04
0
10
20
30
40
50
60
70
-72
10
2.2
5
12
0.5
2
22
7.7
8
36
3.0
8
47
9.5
5
60
1.7
1
66
6.5
9
71
1.7
83
75
6.9
75
80
2.1
68
84
7.3
6
89
2.5
53
93
7.7
45
98
2.9
37
10
28
.13
10
73
.32
2
11
18
.51
5
11
63
.70
7
12
08
.9
12
54
.09
2
12
99
.28
4
13
44
.47
7
Cross section 1846.66
0
10
20
30
40
50
60
70
-48
97
.38
1
14
0.0
4
22
9.0
88
34
6.8
15
46
3.3
7
58
7.8
67
67
8.6
76
72
3.7
12
76
8.7
48
81
3.7
85
85
8.9
87
90
4.6
35
95
0.2
83
99
5.9
31
10
41
.57
9
10
87
.22
6
11
32
.87
3
11
78
.52
2
12
24
.16
9
12
69
.81
8
13
15
.46
5
13
61
.11
3
14
06
.76
Cross section 1913.85
0
10
20
30
40
50
60
-24
10
4.8
81
15
2.8
47
22
4.9
94
32
6.6
1
44
3.0
29
54
5.6
56
66
2.1
17
71
8.7
31
76
2.7
37
80
2.1
2
84
7.2
59
88
5.6
79
93
0.9
96
97
0.2
01
10
14
.38
6
10
54
.72
4
10
97
.77
6
11
39
.24
5
11
81
.16
6
12
23
.76
8
12
64
.55
5
13
08
.29
1
13
47
.94
5
13
92
.81
3
14
31
.33
5
Cross section 1981.04
Carlingwark Lane
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Figure 4
Carlingwark Lane
41.4
41.6
41.8
42
42.2
42.4
42.6
42.8
43
43.2
0 118.42 261.82 415.03 496.12 640.13 897.17 983.95 1056.04 1215.12 1420.97 1644.16 1662.04 1846.66 1913.85 1981.04 2048.23
Long section
0
10
20
30
40
50
60
0
93
.41
16
5.0
8
19
7.1
9
28
8
40
9.7
3
52
9.4
8
64
7.6
5
73
6.1
17
78
2.0
52
82
7.9
87
87
3.9
21
91
9.8
56
96
5.7
91
10
11
.72
5
10
57
.66
11
03
.59
4
11
49
.52
9
11
95
.46
4
12
41
.39
9
12
87
.33
3
13
33
.26
8
13
79
.20
2
14
25
.13
7
14
71
.07
2
Cross section 2048.23
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 2yr
Date
20th June 2013
Dwng No.
1168-202-D1
Peak Water Level 43.63m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 5yr
Date
20th June 2013
Dwng No.
1168-202-D2
Peak Water Level 43.78m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 10yr
Date
20th June 2013
Dwng No.
1168-202-D3
Peak Water Level 43.88m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 25yr
Date
20th June 2013
Dwng No.
1168-202-D4
Peak Water Level 44.06m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 50yr
Date
20th June 2013
Dwng No.
1168-202-D5
Peak Water Level 44.37m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Existing Pump-On 100yr
Date
20th June 2013
Dwng No.
1168-202-D6
Peak Water Level 44.76m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Exisitng Pump-On 200yr
Date
20th June 2013
Dwng No.
1168-202-D7
Peak Water Level 44.98m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Exisitng Pump-On 200yr+GCC
Date
20th
June 2013
Dwng No.
1168-202-D8
Peak Water Level 45.25m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Exisitng Pump-On 1000yr
Date
20th June 2013
Dwng No.
1168-202-D9
Peak Water Level 45.86m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Pump Off 2yr
Date
20th June 2013
Dwng No.
1168-202-D1 O
Peak Water Level 43.63m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Pump-Off 50yr
Date
20th June 2013
Dwng No.
1168-202-D5 O
Peak Water Level 44.37m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
Pump-Off 200yr
Date
20th June 2013
Dwng No.
1168-202-D7 O
Peak Water Level 44.92m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT1 2yr
Date
20th June 2013
Dwng No.
1168-202-D1MIT1
Peak Water Level 43.66m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT2 2yr
Date
20th June 2013
Dwng No.
1168-202-D1MIT2
Peak Water Level 43.64m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT3 2yr
Date
20th
June 2013
Dwng No.
1168-202-D1MIT3
Peak Water Level 43.52m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT4 2yr
Date
20th
June 2013
Dwng No.
1168-202-D1MIT4
Peak Water Level 43.52m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT1 10yr
Date
20th June 2013
Dwng No.
1168-202-D3MIT1
Peak Water Level 43.92m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT1 50yr
Date
20th June 2013
Dwng No.
1168-202-D5MIT1
Peak Water Level 44.43m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT2 50yr
Date
20th June 2013
Dwng No.
1168-202-D5MIT2
Peak Water Level 44.36m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT3 50yr
Date
20th
June 2013
Dwng No.
1168-202-D5MIT3
Peak Water Level 45.01m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT4 50yr
Date
20th June 2013
Dwng No.
1168-202-D5MIT4
Peak Water Level 44.94m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT3 100yr
Date
20th June 2013
Dwng No.
1168-202-D6MIT3
Peak Water Level 45.10m OD
1 Orbital Court
Peel Park
East Kilbride
G74 5PH
Project Title
Carlingwark FRA
Project No.
1168-202
Drawing Title
MIT4 100yr
Date
20th
June 2013
Dwng No.
1168-202-D6MIT4
Peak Water Level 44.93m OD
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
J:\Jobs CDH\1100-1199\1168 - Dumfries & Galloway Council\1168-202 - Castle Douglas\7 - Reports\1168-202 Castle Douglas FRA FINAL Rev
1.doc
PHOTOGRAPHS
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 1 – View from upstream end of Gelston Burn looking north west.
Plate 2 – View of upper Gelston Burn looking south east.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 3 – View of Carlingwark Loch looking north west.
Plate 4 –
Plate 4 – View of shore area around Carlingwark Loch near Isle of Whitepark.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 5 – Looking south towards Carlingwark House. Note new sewage treatment facility on left.
Plate 6 – Carlingwark Lane looking north east from the A75 road bridge.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 7 – Looking north west towards the Blackparks Pumps from the A75 bridge.
Plate 8 – Upstream side of the Blackparks pump station.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 9 – View of low lying ground on the downstream side of the Blackparks Pump station.
Plate 10 – Looking south west from Blackpark Smallholdings towards the pump station.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 11 – Looking north from Meikle Wood Hill towards Threave Castle.
Plate 12 – From Meikle Wood Hill looking north east with the Blackparks Pump station in the middle distance.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 13 – Downstream side of Blackparks Pump station (pumps currently in action).
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 14 – Upper part of Carlingwark Lane showing constricting channel growth.
Plate 7 –
Plate 15 – View of upstream side of A75 road bridge.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 17 – View of non-return culvert gates at Blackparks Pump station.
Plate 16 – View of Carlingwark Lane from pump station looking downstream
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 18 – Looking south from the pump station.
Plate 19 – View of upstream side of pump station.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 20 – Carlingwark Lane looking towards the A75 bridge.
Plate 21 – Carlingwark Loch and the Buchan Bridge outfall.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 23 – Constriction downstream of Buchan Bridge.
Plate 22 – View below Buchan Bridge.
CASTLE DOUGLAS
FLOOD RISK ASSESSSMENT
FOR
DUMFRIES & GALLOWAY COUNCIL
Plate 24 – Excavated section of Carlingwark Lane downstream of
Buchan Bridge.
CASTLE DOUGLAS
FLOOD RISK ASSESSMENT
FOR
DUMFRIES AND GALLOWAY COUNCIL & SCOTTISH POWER
J:\Jobs CDH\1100-1199\1168 - Dumfries & Galloway Council\1168-202 - Castle Douglas\7 - Reports\1168-202 Castle Douglas FRA FINAL Rev
1.doc
TABLES
FEH QMED (using
2007 methodology)
combined with
Growth curve
FEH QMED (using
2008 methodology)
combined with
Growth curve
IHR 124
Rural
(Catchments
<25km2)
Rainfall
Runoff
Methodology
(MIKE)
SEPA
Statistical
Analysis
Mouchel
2008 report -
Statistical
Method
Mouchel 2008
report - Rainfall
Runoff Method
Adopted
Peak Flow
200 year 779 886 n/a 1401 541 495 n/a 495
200 year plus potential Global
Climate Change (GCC) of 20% 935 1063 n/a 1681 649 594 n/a 594
200 year 777 902 n/a 1417 n/a 528 n/a 528
200 year plus potential Global
Climate Change (GCC) of 20% 932 1082 n/a n/a 634 n/a 634
200 year 13 18 29 86 36 n/a 36 36
200 year plus potential Global
Climate Change (GCC) of 20% 15 21 34 103 43 n/a 44 43
Note: FEH CD-ROM 3 Dataset used
River Dee at
Bridge of Weir
Carlingwark
Lane at Castle
Douglas
Table 1 - Summary of Peak 1 in 200yr Flow Rates
All flow volumes are expressed in m3/s
River Dee at
Glenlochar
Job No: 1168-202
2 year 5 year 10 year 25 year 50 year 100 year 200 year
200 year plus
potential Global
Climate Change
(GCC) of 20% 1000 year
River Dee at Glenlochar 238 301 341 391 247 461 495 594 1938
Carlingwark Lane at Castle Douglas 11 15 18 23 27 32 36 43 53
Table 2 - Summary of Peak Flow Rates for a Variety of Return Periods All flow volumes are expressed in m3/s
Job Number 1168-202
Blackparks Pump On
throughout storm event.
Blackparks Pump Off
(failed or switched off). MIT 1 MIT 2 MIT 3 MIT 4
2 Year 43.63 43.63 43.66 43.64 43.52 43.52
5 Year 43.78
10 Year 43.88 43.92
25 Year 44.06
50 Year 44.37 44.37 44.43 44.36 45.01 44.94
100 Year 44.76 45.09 44.93
200 Year 44.98 44.92 44.97
200 Year plus GCC 45.25
1000 Year 45.86
Explanatory Notes: All levels are expressed in relation to OD,
Pre Storm Carlingwark Loch Water Level of 43.5m
Blackparks bund at about 45.00m OD
Exsisting Conditons Freeflow of water throughout system except at Blackparks with one way gate culverts and twin automatic pumps
MIT 1 Repair of Blackparks bund to 45.45mOD, Blackparks pumps off, Gill Burn control with weir at 45.5mOD and culvert with capacity of about 10m3/s
MIT 2 Repair of Blackparks bund to 45.45mOD, Blackparks pumps off
MIT 3 Repair of Blackparks bund to 45.45mOD, Blackparks pumps off, Gill Burn control with weir at 45.5mOD and culvert with capacity of about 2.5m3/s
MIT 4 Repair of Blackparks bund to 45.45mOD, Blackparks pumps off, Gill Burn control with weir at 45.5mOD and culvert with capacity of about 2.5m3/s, A75 one way gate.
Job Number 1168-202
Table 3 - Peak Water Levels around Isle of Whitepark
Existing Conditions Mitigation Measures