River Irwell Along Radcliffe Bury Engineering Essay

The River Irwell is made up of 13 catchments in the North West part that drain of course into the individual river system ( EA, 2008a ) . The catchment covers an estimated 700 square kilometers with over two million people within its locality ( ref ) . Two of the 13 catchments are responsible for the conducive consequence of river implosion therapy in Radcliffe along the River Irwell. The small town of Radcliffe located south-west of Bury is made up of three wards ; Radcliffe North, East and West. It derived the name Red-cliff as a bank on the river Irwell filled with rocks and it is celebrated for its many mediaeval edifices. Its resident population is an estimated 33,149 which represents about 18 % of the Bury population as at 2007 mid-year population estimations. The survey country in focal point is a 10.06km subdivision of the river Irwell get downing from the Bury evidences catchment and fluxing down watercourse towards Radcliffe West, with an influx from the river Roch catchment at the Blackford Bridge. The figure 3.2 below is the FEH CD-ROM geographical interface developed by the Centre for Ecology and Hydrology ( CEH ) demoing the Bury land and the Blackford Bridge catchment forms ; this Flood Estimation Handbook ( FEH ) provides counsel on rainfall and river inundation frequence appraisal throughout the UK with a latest version printed in 2008.

Figure 3.1: Map demoing the Radcliffe country in Bury

Beginning ; Bury Metropolitan Council ( 2007 )

Figure 3.2: Screenshot from the FEH CD-ROM 3 demoing the catchment forms for the River Irwell at Bury,

Beginning: Wallingford Hydrosolutions Ltd ( 2009 )

3.2 Data Available

For the 10.06 kilometers reach country of survey along the river Irwell, geo-referenced cross-sections closest to the catchment forms were made available by the EA ( 2010 ) . The information was nevertheless non complete as, there was still a big parts of the river unmarked by the surveyed cross subdivisions.

A LiDAR 10 metre declaration DTM with ( cell size X, Y ) and a pixel deepness of 32 spot was downloaded from the LANDMAP Kaia web site in an ASCII format ( recognizable by the package, such as ArcGIS and MapInfo ) , with co-ordinates fiting the survey country with mention to the British National Grid.

A high graduated table Ordinance Survey ( OS ) raster map with a graduated table of 1:10 000 was made available by download signifier the Ordinance Survey web site. Physical characteristics of this big scale up-to-date map includes ; edifices, rivers, route or rail and other substructure around the environments of Radcliffe, Bury.

3.3 The Model Used

The rating of this survey is undertaken by utilizing the available informations to back up modeling of the Major inundation event which occurred in January-February 1995 and 2008 along the river Irwell and the modeling bundle in usage, is the ISIS 3.3v a package bundle developed by Halcrow Group used for river modeling intents to showcase inundation prediction, inundation hazard function, every bit good as appraisals. However, the ISIS 3.3v produced tardily in 2009 had some ascents form the former, as the new interface characteristics included ISIS Mapper which enables the creative activity of hydraulic theoretical accounts built from a web of bing geo-referenced informations sets for better analysis of consequences and visualizing of 1D or 2D modeling end products.

The ISIS theoretical account makes usage of one-dimension numerical solution for bring forthing steady and un-steady simulation of inundation extension consequences along the modelled river channel. The river in this instance is represented utilizing surveyed cross-sections which are so linked to floodplain storage cells ( reservoirs ) with the usage of spill units which compute the exchange of H2O between the river flow and the reservoirs.

In the ISIS Mapper interface, all inputted theoretical account units were built up utilizing GIS processing to pull out informations from the digital terrain theoretical account ( DTM ) provided for this survey so as to fit the theoretical account with bing informations associating to the geographical surface country, as “ DTM are deduced chiefly from the observation of the terrain surfaces which represent the bare Earth at some degree of item ” ( Karel et. Al, 2006 ) .

Figure 3.3: digitised River Irwell at the survey country together with reservoirs and slop units, in MapInfo

3.4 Model Building

First, the survey subdivision of the river Irwell ( 10.06 kilometers long ) was digitised in MapInfo, together with the spill units and reservoirs which were digitised along side the river, chiefly by observation of bing reservoirs on the Survey Map provided, after which the result was imported into the ISIS plotter for analyzing. This is to back up the construct of constructing a hydraulic theoretical account, were the assorted informations used relates to the physical informations derived from the O.S map ( Wicks et Al, 2004 ) . However, in the chief ISIS interface node labels are being assembled to accommodate the theoretical account, as these included the theoretical account extents get downing with the a flow-time boundary ( QTBDY ) IRWE05_2618 denoting the mean flow of the river as 15m3/s and a clip interval of 0 hours – 27 hour for runtime and connected by a junction to an upstream influx boundary ( REFHBDY ) IRWE05_2618f which contains gauged information of Bury Ground catchment form, after which a series of the surveyed cross-sections were added as node points to the construction. The tabular array ( ) below shows the cross-sections informations provided by the EA ( 2010 ) incorporating information on 3 different range lengths that form the river Irwell survey country.

Unit of measurement LABEL

A

IRWE05_2618

River Section

IRWE05_2162

River Section

IRWE05_2081

River Section

IRWE05_2043

River Section

IRWE05_1960

River Section

IRWE04_3031

River Section

IRWE04_2875

River Section

IRWE04_2688

River Section

IRWE04_2536

River Section

IRWE04_2192

River Section

IRWE04_1979

River Section

IRWE04_1792

River Section

IRWE04_1698

River Section

IRWE04_1621

River Section

IRWE04_1503

River Section

IRWE04_1457

River Section

IRWE04_1155

River Section

IRWE04_0926

River Section

IRWE04_0753

River Section

IRWE04_0559

River Section

IRWE04_0436

River Section

IRWE04_0312

River Section

IRWE04_0232

River Section

IRWE04_0146

River Section

IRWE04_0001

River Section

IRWE03_6022

River Section

IRWE03_5862

River Section

Table 3.1: screening River Sections

Along the survey river, the first series of cross-section informations ( IRWE05_2618 – IRWE05_1960 ) had a long spread of ( ) kilometer before the following river subdivision informations IRWE04_3031. However, this prompted the demand to make full the spreads with cross-section information utilizing a tool within the ISIS Mapper environment, there by importing the created nodal information in the ISIS environment to the ISIS Mapper environment for better ocular analysis. The downloaded 10m DTM was uploaded into ISIS Mapper, together with the digitised river shapefile and were both matched together so the river information ( depth degree ) was picked form the contour of the DTM after which the insert cross-section tool was used to add cross-sections in the river spread. The specific distance between the new set cross-sections added were specified in the tool box and this covered all countries of the 10.06 kilometer river length which was digitised in MapInfo for the intent of the survey. The new river Sections added to the survey river are shown in tabular array ( ) .

River Label

A

IM_0092

River Section

IM_0087

River Section

IM_0083

River Section

IM_0078

River Section

IM_0077

River Section

IM_0074

River Section

IM_0071

River Section

River Label

A

IM_0068

River Section

IM_0094

River Section

IM_0036

River Section

IM_0040

River Section

IM_0043

River Section

IM_0044

River Section

IM_0046

River Section

Table 3.2: screening freshly inserted River Sections

After the new set of river subdivisions were added, it was observed that the spreads between each of the new cross-sections were still greater than that of the provided river subdivisions. This nevertheless, was addressed by supplying interpolates to associate the spreads between the assorted cross-sections which was done with the usage of an interpolator tool produced by Halcrow Group. This ISIS Interpolator version 3.10 was used to place the whole length of the Study River and so put the maximal distance to 150 m between interpolates and to the following river subdivision. This produced the undermentioned consequences seen in table ( ) .

Unit of measurement Label

A

IRWE_2618_1

Interpolates

IM_0092_1

Interpolates

IRWE_1960_1

Interpolates

IRWE_1960_2

Interpolates

IRWE_1960_3

Interpolates

IM_0087_1

Interpolates

IM_0087_2

Interpolates

IM_0087_3

Interpolates

IM_0087_4

Interpolates

IM_0083_1

Interpolates

IM_0083_2

Interpolates

IM_0083_3

Interpolates

IM_0083_4

Interpolates

IM_0078_1

Interpolates

IM_0077_1

Interpolates

IM_0077_2

Interpolates

IM_0077_3

Interpolates

IM_0074_1

Interpolates

IM_0074_2

Interpolates

IM_0074_3

Interpolates

IM_0071_1

Interpolates

IM_0071_2

Interpolates

IM_0071_3

Interpolates

IM_0068_1

Interpolates

IM_0068_2

Interpolates

IRWE_3031_1

Interpolates

IRWE_2875_1

Interpolates

IRWE_2688_1

Interpolates

IRWE_2536_1

Interpolates

IM_0094_1

Interpolates

IRWE_2192_1

Interpolates

IRWE_1979_1

Interpolates

IRWE_1457_1

Interpolates

IRWE_1457_2

Interpolates

IRWE_1155_1

Interpolates

IRWE_0926_1

Interpolates

IRWE_0753_1

Interpolates

IRWE_6022_1

Interpolates

IRWE_5862_1

Interpolates

IM_0036_1

Interpolates

IM_0036_2

Interpolates

IM_0036_3

Interpolates

IM_0040_1

Interpolates

IM_0040_2

Interpolates

IM_0040_3

Interpolates

IM_0043_1

Interpolates

IM_0044_1

Interpolates

IM_0044_2

Interpolates

IM_0044_3

Interpolates

Table 3.3: demoing cross-section interpolates

3.4.1 Reservoirs and Spill units

These are created to stand for the flood plains or channel interaction used in countries where the flood plain inclines upwards off from the river channel without any signifier of embankments. These reservoir units, merely like the river form file are matched against the DTM to pull out Elevation and Area relationships for each of the reservoir units which are connected the river channel by spill units, which in this instance are used to let H2O spill over into the reservoir ( flood plain ) once it is out of Bankss. This gives a graphical presentation the flow path between the river channel and the reservoirs, as the creative activity of each reservoir was with regard to what was observed on land through the 1:10 000 OS street map and Google Earth with the purpose of extinguishing countries with bing inundation defense mechanisms.

Unit of measurement Label

A

IM_0083LD

Reservoir

IM_0071_3LS

Spill

IM_0071_2LS

Spill

IM_0071_1LS

Spill

IM_0071LS

Spill

IM_0074_3LS

Spill

IM_0074_2LS

Spill

IM_0074_1LS

Spill

IM_0074LS

Spill

IM_0077_3LS

Spill

IM_0077_2LS

Spill

IM_0077_1LS

Spill

IM_0077LS

Spill

IM_0078_1LS

Spill

IM_0078LS

Spill

IM_0083_4LS

Spill

IM_0083_3LS

Spill

IM_0083_2LS

Spill

IM_0083_1LS

Spill

IM_0083LS

Spill

IM_0077RD

Reservoir

IR2688_1RS

Spill

IM_0071RS

Spill

IM_0074_3RS

Spill

IM_0074_2RS

Spill

IM_0074_1RS

Spill

IM_0074RS

Spill

IM_0077_3RS

Spill

IM_0077_2RS

Spill

IM_0077_1RS

Spill

IM_0077RS

Spill

IM_0071_1RD

Reservoir

IR04_2688RS

Spill

IR2875_1RS

Spill

IR04_2875RS

Spill

IR3031_1RS

Spill

IR04_3031RS

Spill

IM_0068_2RS

Spill

IM_0068_1RS

Spill

IM_0068RS

Spill

IM_0071_3RS

Spill

IM_0071_2RS

Spill

IM_0071_1RS

Spill

IR04_3031LD

Reservoir

IR1979_1LS

Spill

IR04_1979LS

Spill

IR2192_1LS

Spill

IR04_2192LS

Spill

IM_0094_1LS

Spill

IM_0094LS

Spill

IR2536_1LS

Spill

IR04_2536LS

Spill

IR2688_1LS

Spill

IR04_2688LS

Spill

IR2875_1LS

Spill

IR04_2875LS

Spill

IR04_3031LS

Spill

IR3031_1LS

Spill

IM_0094RD

Reservoir

IR04_0232RS

Spill

IR04_0312RS

Spill

IR04_0436RS

Spill

IR04_0559RS

Spill

IR0753_1RS

Spill

IR04_0753RS

Spill

IR0926_1RS

Spill

IR04_0926RS

Spill

IR1155_1RS

Spill

IR04_1155RS

Spill

IR1457_2RS

Spill

IR1457_1RS

Spill

IR04_1457RS

Spill

IR04_1503RS

Spill

IR04_1621RS

Spill

IR04_1698RS

Spill

IR04_1792RS

Spill

IR1979_1RS

Spill

IR04_1979RS

Spill

IR2192_1RS

Spill

IR04_2192RS

Spill

IM_0094_1RS

Spill

IM_0094RS

Spill

IR04_0559LD

Reservoir

IR6022_1LS

Spill

IR03_6022LS

Spill

IR04_0001LS

Spill

IR04_0146LS

Spill

IR04_0232LS

Spill

IR04_0312LS

Spill

IR04_0436LS

Spill

IR04_0559LS

Spill

IR03_5862LD

Reservoir

IM_0036_3LS

Spill

IM_0036_2LS

Spill

IM_0036_1LS

Spill

IM_0036LS

Spill

IR5862_1LS

Spill

IR03_5862LS

Spill

IM_0036RD

Reservoir

IM_0040_3RS

Spill

IM_0040_2RS

Spill

IM_0040_1RS

Spill

IM_0040RS

Spill

IM_0036_3RS

Spill

IM_0036_2RS

Spill

IM_0036_1RS

Spill

IM_0036RS

Spill

Table 3.4: screening full Reservoir and Spill units

With the collection of all the river subdivisions, slop units and reservoirs in alliance with the river line in ISIS Mapper, all the information gathered with statistical analysis derived from the DTM was so saved as an ied.file and imported into the ISIS environment for the intent of dwelling the node tabular array to guarantee the successful tally of the theoretical account. The nodal inputs begin wit a flow-time boundary ( QTBDY ) IRWE05_2618 of 15 m3/s connected to a catchment form ( REFHBDY ) IRWE05_2618f from the Bury land gage station and joined to a downstream river-section IRWE05_2618d with the usage of a junction ( ) , to bespeak the start-up of the survey river fluxing downward watercourse and a 2nd catchment form ( REFHBDY ) IRWE04_1698f meaning an in-flow from the Blackford span gage station was connected to the river subdivision IRWE04_1698d with a junction ( ) and still fluxing downstream of the river. ‘The nodal points in the ISIS environment are normally connected by junction nodes ( bespeaking all linking nodes ) or by holding similar node labels ‘ . The undermentioned river subdivisions ( both the subdivisions provided by the EA together with the freshly created river subdivisions ) together with all the Interpolates, Reservoirs and Spill units were all created with node label points to accommodate their several maps in the ISIS interface. The following were represented in the ISIS environment as below ;

Unit of measurement LABEL

Unit of measurement DIAGRAM

River Section

A

Interpolate

A

Reservoir

A

Spill

Table 3.5: screening unit labels that do up the theoretical account

From the information on Bridgess and weirs provided by the EA ( 2010 ) and harmonizing to ocular observation from the OS street position map, every bit good as Google Earth, the undermentioned information on each bing construction was gathered so as to suit the intent of the theoretical account construct up which was done in the ISIS environment so as to associate the affected river subdivisions to the available constructions.

3.4.2 Bridges

These span constructions are being modelled as span units which is represented by a span arch unit node label ( ) to stand for the loss of H2O across the construction with the input of spill units in analogue besides to show the flow of H2O over and around the construction once it becomes surcharged. The EA provided surveyed information on two ( 2 ) Bridgess while the 3rd ( 3rd ) span information was worked out ( as it was identified as an bing characteristic through Google Earth ) utilizing information from the river-sections and doubling the tallness of a similar span with already provided information and there were three ( 3 ) span units created.

Unit of measurement LABEL

A

IRW05_2081bu

Bridge

IRW05_2081su

Spill

IRW03_5862bu

Bridge

IRW03_5862su

Spill

IM_0036bu

Bridge

IM_0036su

Spill

Table 3.6: screening Bridge unit and Spills

3.4.3 Weirs

These are provided for assorted cardinal grounds and in most instances for channel stabilization ( Rickard et al, 2003 ) . The weir located along the river channel in this survey, is represented by a round-nosed wide crested weir ( ) from the label nodes. This represents the extent and magnitude of the existent weir along the survey country. Information on the Weir was non provided hence, it was identified with the aid of Google Earth. The tallness and breadth of the weir was determined through the aid of Arc tools in the ArcGIS environment. The unit is displayed as IM_0077wu.

After all the node units were inserted into the ISIS environment in the order of the watercourse flow ( from up-stream to down-stream ) , the last river subdivision ended with a normal/critical deepness boundary node ( ) holding similar labels ( IM_0046 ) with the cross-section to tag the terminal of the tally theoretical account. This enabled the successful tally of an unsteady simulation in with an ‘adaptive timestep ‘ scheme of initial timestep of 5s and a save interval of 300s ( seconds ) running from a start clip of 0hrs to a finish clip of 27hrs ( hours ) . Whilst the tally is in advancement, ISIS produces artworks which follow the simulation and logs any mistake or warnings into a diagnostic file.

Each of the in-flow catchment forms ( REFHBDY ) is set to a 5yr ( rear ) flood return period to bring forth end product consequences in hydrographs for analyzing and the terminal tally of the theoretical account produces an end product ‘Animated Simulation ‘ to demo the extent of the river spill in a inundation event happening and besides end product hydrographs can be used to analyze the flow of the river after the theoretical account is run.

The geographical location of the theoretical account nodes which is integrated within the theoretical account produces a conventional diagram. This conventional produces is unvarying graduated table georeferenced map, which enables ocular in writing sing harmonizing to location of cross-sections and besides facilitates future updating of the theoretical account. This enable the theoretical account outputs to straight associate into spacial tools for analysis of consequences. This is viewed in the ISIS environment by choosing the GIS visualiser ( ) .

Figure 3.4: shows the produced conventional diagram of the survey country along with assorted parametric quantities used in puting up the theoretical account.

3.5 Data Restrictions

Due to the inaccessibility of most existent surveyed cross-sections, together with deficiency of specific informations on the Bridgess and weirs which could non be taken into consideration during the theoretical account edifice posed a little restriction to the range of the survey. The low declaration DTM besides had some restrictions as a much lower declaration ( i.e. 2.5m or 1m ) would hold produced a better analysis of the theoretical account creative activity. However, the theoretical account ‘s prognostic ability was non affected in anyhow and it produced accurate and similar information when compared to the end product consequences produced by the EA.

3.6 Model proving

1:5yr design flow Vs. January, 2008 simulated flow.

Figure 3.5: Hydrographs of Observed vs. Modelled/Simulated flow for the Blackford span catchment

There were high extremum flows recorded for Bury land and Blackford span catchment in the month of January 1995 and 2008 severally ( EA, 2010 ) . The 15 proceedingss flow informations was provided by the EA and used to compare the extremum flow for a 1:5 twelvemonth return period in the design theoretical account. The end product consequences were transported to Microsoft Excel spreadsheet and a graph produced for analyses. The ascertained river flow at the Blackford Bridge for January, 2008 was maintained at 119m3/s ( as recorded ) and the 1:5 twelvemonth design flow produced 126m3/s. This statistical attack combines index inundation with growing curve from observed informations. Therefore, the addition observed organize the design flow depicts what the theoretical account is designed to propagate.