Areas of Expertise
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Pehur High Level Canal
The Pehur High Level Canal, North-West Frontier Province, Pakistan. This is thought to be the world’s largest true parabolic canal, designed by Adrian Laycock.
The parabolic profile of concrete lining is superior to the normally-used trapezoidal
section and imparts great strength and resistance to cracking from slumping, settlement or
soil movement. It is also easy to construct using a rotating striker tube.
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This canal is 26 km long with a capacity of 30 m3/sec. It is designed for downstream control with self-regulating gates,- the first canal in Pakistan to be automated in this way. Adrian Laycock was Chief Design Engineer for Lahmeyer International on this project. |
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| Construction | |
Above: The main earthworks are done by machine. |
Above: The screed bars are cast at 6 metre intervals using a special formwork to accurately level and form the parabolic profile. |
Above: Final trimming is done between screed bars, and a layer of blinding concrete fills in any overbreak. |
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Above and Left: Concrete is poured and placed using a Bunyan striker tube. This is a steel tube which rotates against its direction of travel, compacting and spreading the concrete as it goes. It is commonly used for laying flat slabs, but was originally conceived for laying trapezoidal canal lining in California. The parabolic shape is especially suited to this form of construction. |
Why parabolic?
Most canals are built to a trapezoidal profile. Parabolics offer several advantages:
Strength. The shell shape offers great structural strength with no points of weakness such as occur in a trapezoidal profile.
Ease of construction. No problems of slumping or tension cracking during concrete placement that occur near the base of a trapezoidal slope. The actual gradient of the lower profile is much flatter than for a trapezoidal.
Cost. Volume of concrete and excavation can be reduced over an equivalent trapezoidal profile.
Speed. This method of construction is fast. Slipforming can also be used, although the machinery is expensive.
Beauty. It is a rare thing for engineers to combine functionality with beauty, but here it is.
Installation of downstream control gates
The self-regulating float-controlled gates are designed to automatically regulate the downstream water level to a predetermined level. With downstream control, flexibility of supply on the main canal system is guaranteed. Response time of the 100 mile-long canal system is cut from days to hours, and wastage of water and power generation at Tarbela Dam can be reduced.
 Above: Orifice type gate at the outlet of Kundal Siphon. The siphon will carry 30 cubic metres/second over a length of 1.8 km, controlled by two of these float-operated gates. |
 Above: Kundal Siphon outlet structure. |
 Above: A cross regulator on Maira branch Canal under construction. |
 Above: Installing the self-regulating gates. |
 Above: Interior of the completed regulator structure. |
 Above: Upstream view of the completed cross regulator. |
 Above: Howell Bunger valves discharging water from Tarbela Dam into the head of the Pehur High Level Canal, January 2003 |
 Above: The Pehur High Level Canal during commissioning trials, March 2003 |
Commissioning the Pehur High Level Canal, October 2003
 Above: Adjusting downstream control gates on the Pehur Canal. |
 Above: Adjusting downstream control gates on the Pehur Canal |
 Above: Gandaf Tunnel Outlet into the head of Pehur high level canal. Howell-Bunger valves. |
 Above: Free discharge valves in operation |
 Above: Free discharge valves in operation. |
 Above: A flow division structure on a minor canal. |
 Above: A labyrinth escape weir on the main canal. |
Merowe Irrigation Project, Sudan
This massive project is now undergoing detailed design. A dam on the Nile is already under construction at the 4th
cataract. The irrigable area will extend for 400 kilometres downstream. Adrian Laycock is irrigation design consultant
to Lahmeyer International. The irrigation system will include pumping and parabolic gravity canals, and automatic
pipeline distribution systems. The terrain is extremely hostile and requires some careful engineering. Existing
projects in the area have been affected by salinity, moving sand dunes, waterlogging and dispersive silts which
have severe constraints on canal design and operation.
Irrigation Rehabilitation (Pakistan)
A proportional division structure on the Swabi SCARP irrigation rehabilitation project, Pakistan.
A design introduced by Adrian Laycock as a means of passive automation for this century-old project
of 100,000 hectares.
Precast Parabolic Canal
Small precast parabolic canal. Adrian Laycock has introduced these in Indonesia, India and Pakistan, where
they have proved a runaway success in rehabilitation of watercourses. They are made of high strength
unreinforced concrete and can be fabricated under controlled conditions in small casting yards,
providing basic principles of quality control are followed. They have the triple advantages of
being cheap, long-lasting and hydraulically efficient.
The Yeleru Left Bank Canal
The Yeleru Left Bank Canal carries water 150 km to the new industrial
town of Vishakapatnam in Andra Pradesh, India. The canal leaks badly and
is severely affected by instability of its side slopes which are in deep
cut for much of its length. Adrian Laycock is consultant to Lahmeyer
International in formulating engineering rehabilitation works, including
bentonite grouting of canal banks, slope stabilisation, canal lining and
desilting.
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Irrigation Rehabilitation (Albania)
Albania - rehabilitation of irrigation schemes.
Top right - A pump station near Vlore.
Below left - Saline land near Vlore.
Below right - Rehabilitation of irrigation schemes amidst the Fier oilfield.
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Radial-Gated Cross Regulator
Radial-gated cross regulator on the Machai Branch Canal, Pakistan, designed by Adrian Laycock.
Elliptical transitions are used to good effect.
Semi-closed Pipeline Network
Installing a low-pressure semi-closed pipeline network, Pakistan. The design principles of this demand-scheduled irrigation system are quite different from those normally used. The tail-end problem is eliminated, and farmers are able to take water at any time to suit themselves or their crop, without being restricted to a tightly-regimented supply schedule.
This is a new concept for Pakistan and represents a major shift from traditional irrigation principles.
The design procedures were developed by Adrian Laycock, based on the philosophies of Professor John L
Merriam. Pressure control is achieved through float-operated Harris Valves.
Land Drainage in Argyll
This work became necessary after the installation of a sewer pipeline caused
damage to an existing underground field drainage system. A field is being
re-drained using gravel and geotextile filters.
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Irrigation Engineering Portfolio
Adrian Laycock Ltd was established in 1982 and has been active in irrigation development in the following countries :
| ALBANIA | Feasibility studies for rehabilitation of irrigation schemes up to 9,000 hectares. |
| AFGHANISTAN | Design of river training and erosion control works |
| BRUNEI | Design of urban drainage and river control |
| BURMA | Feasibility studies for small-scale irrigation |
| ETHIOPIA | Design and field investigations for a sugar estate |
| GREECE | Environmental rehabilitation of Lake Koronia |
| INDIA | Rehabilitation of Yeleru Left Bank Canal, Andra Pradesh |
| INDIA | Rehabilitation of small irrigation projects, Karnataka |
| INDONESIA | Design and implementation of sugar estates |
| INDONESIA | Rehabilitation of conjunctive use irrigation schemes |
| KAZAKSTAN | Appraisal mission for Aral sea environmental rehabilitation |
| KIRGISTAN | Appraisal mission for Aral sea environmental rehabilitation |
| NIGERIA | Design of irrigation projects and earth dams |
| PAKISTAN | Design of Pehur High Level Canal |
| PAKISTAN | Rehabilitation of Swabi SCARP Irrigation Project |
| SRI LANKA | Water Management studies, Victoria Project, Mahaweli System |
| SUDAN | Establishment of training programme for irrigation staff on the Gezira Project |
| SUDAN | Feasibility and detailed design for Merowe Irrigation Project |
| SYRIA | Feasibility study for El Ghab Project |
| TANZANIA | Feasibility Study, Stieglers Gorge Project |
| UZBEKISTAN | Appraisal mission for Aral Sea environmental rehabilitation |
| ZAMBIA | Rehabilitation of coffee estates |
The company was set up to work on the interface between civil engineering and other disciplines such as agriculture, ecology, the environment, sociology, management, economics, soil conservation, which come together in most irrigation projects and often give rise to conflicting solutions for development.
Operating from its base in Scotland, Adrian Laycock Ltd is a small scale organisation which maintains close working links with independent specialist consultants in related fields. Much of its work is in providing specialist expertise to larger international consultants.
