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Operation Tethys

Steve Matthews

Steve Matthews is an engineering geologist working with the British Army in Helmand Province, Afghanistan, helping to repair the irrigation systems of the region.

Geoscientist 21.06 July 2011

As the heavily armoured British Army Mastiff truck rumbled to a halt, the machine gunner in the top turret swung his weapon through 180 degrees and called his arc of view clear. The engine noise died away to a low hum. The commander leant back into the crew compartment and gave us the thumbs up. I checked my SA80 A2 rifle, kicked the heavy doors open and stepped down into a spectacular Afghan dawn. Operation Tethys, the Royal Engineers’ contribution to the reconstruction of Helmand Province’s irrigation system, had begun.

The British Army has had established posts for a small number of geologists for nearly a century, the first operational British Army Geologist (William Bernard Robinson King) deploying to France to supervise well drilling during WW1. Since 1945, these geologists have been reservists drawn like me from the Territorial Army, who practise geology professionally as civilians but maintain basic military skills through an annual part-time training programme. Although the Ministry of Defence uses civilian consultants in the same way as any other government department, there are occasions where, for security or operational reasons, Royal Engineers Geologists are called upon to provide specialist expertise. Operation Tethys was such a project.

Operation Tethys was conceived by the Royal Engineers 170 (Infrastructure Support) Group as a means of assisting the reconstruction of the Helmand Valley irrigation system in late 2010. A number of critical project sites had been identified, where failing earthworks and mechanical systems were threatening operational integrity. The Provincial Reconstruction Team (PRT), based in Lashkar Gah, had sourced international for the project, which clearly needed to liaise with the Helmand and Arghandab Valley Authority (HAVA - the Afghan organisation responsible for managing the canal system) in order to convert initial outline concepts into deliverable projects. Many of these were located in areas where civilian staff movement was difficult because of the security situation.

Operation Tethys, therefore, consisted of a six-man team drawn from both regular and reserve Royal Engineers. The team contained men with expertise in relevant disciplines (two civil engineers, a mechanical engineer, a coastal defence specialist, and an engineering geologist) as well as the military capability to slot seamlessly into the existing security patrol profile, fighting if and when required. Its mission was, in summary, to conduct site reconnaissance at the critical project sites and design achievable solutions in partnership with HAVA.

Mastiff on Pebble beds


The Helmand Valley winds south from the Hindu Kush, south to the Iranian border. The Valley comprises a wide braided alluvial plain, cutting through the broad deserts of the Sistan depression (west) and the Registan desert (east). The underlying solid geology consists mainly of Neogene conglomerates and sandstones with some evidence of volcanics; however in the vicinity of the inhabited area of the valley these rarely poke above the (variably) thick layer of alluvium and loess overlying them. These deposits consist of interbedded sand, cobble and silt layers, and reflect a postglacial history of turbulent change by changes in river course and desert encroachment. The alluvium shows remarkable variation in composition, but all the pebbles are highly rounded and very hard, deriving mainly from igneous and metamorphic rocks over 100km to the north.

The Helmand irrigation system originally comprised short, hand-dug canals taking water directly from the Helmand and Arghandab rivers. Several systems were gradually developed in this way from prehistoric times. The area has a long history of civilisation, featuring in the campaigns of Alexander the Great (who constructed the spectacular fort at Kala-i-Bost) and Genghis Khan (who destroyed it), as well as more recent involvement with British and Soviet empires. Approximately 1.4 million people now live in the valley, whose economy is mainly based on agriculture. Various internal investment and foreign aid programmes supported by the Americans and Russians led to the widespread construction of large canals and reservoirs, which provided a degree of control over the highly seasonal rivers, and allowed the cultivable area to be expanded into formerly arid desert territory.

The Ruins of Kala-i-Bost For


Years of neglect between the 1989 Russian withdrawal and recent international intervention resulted in many problems; by far the most critical being at a series of sites where the river was eroding its course towards existing artificial canal embankments. Some were already showing signs of failure. Should breaches occur, the river could allow the canal system to drain down all the way from the breach back up to the next inlet – in some cases many kilometres away. Such an event would render the irrigation system useless; leaving the population either dependent on direct aid, or more likely, faced with having to move out.

Protecting these potential breach sites involved providing an engineered buffer. This was not necessarily waterproof, but provided a barrier against mechanical scour. Given the scale of the problem and the availability of resources, it became apparent that gabion baskets filled with local gravel and cobbles would be the optimal value-for-money solution. Having reached that point it remained only to identify where these walls should be installed, what the profile would be, and check that potential source materials for fill were close at hand.

The use of rounded cobbles (crushing and screening would be impossible) imposed an engineering constraint, in that gabion walls cannot be constructed vertically using such material. The tendency of the cobbles to act like marbles in a bag leads to the gabions becoming golf-ball shaped, destabilising the wall. These new walls were therefore designed with a degree of layback, and the wisdom of this decision was illustrated on one site recce, where an existing gabion wall (not one of ours!) at a nearby location was being dismantled as it had failed in just this way. Vertical gabion walls had been constructed in the region, but using precast concrete blocks. The difficulty of supply and quality control at remote sites led us to discount this option for the first set of sites.

Operation Tethys recce teams deployed to six key sites through November 2010, after training in the UK and Afghanistan during October. Having undertaken site recces and a limited amount of survey, designs were produced and tender documents assembled for local contractors. By the end of November, the team conducted appraisals of contractor proposals before departing for the UK. At time of writing (December 2010) we understand that the projects will go ahead in 2011, and the plan is for further Operation Tethys teams to provide support to these existing projects and develop new ones.

Environment Agency Officer Richard Hull Cleaning his Rifle at a Forward Operating Base.


Operation Tethys was a small but key element in the reconstruction effort in Helmand Province. Although the main effort was to secure the sites giving concern rapidly, the underlying theme of the operation – in common with most of international effort in Afghanistan - is to build (and rebuild) capacity in the local economy. Once the irrigation system is secured and running efficiently and predictably again, it should contribute significantly towards an economic ‘virtuous cycle’. Farmers will be are able to maximise output, and can then be charged for the water that enables them to do so. This money will then fund maintenance and improvement, and provide employment for both a permanent cadre of engineers and operatives in HAVA, and for local civil engineering contractors.

Tethys was also a departure for the Royal Engineers. For most operations, ‘critical Infrastructure’ means roads, accommodation, railways, ports, airfields, drinking water and power supply. Irrigation is a new category, but given the potential influence of the Helmand Irrigation System on the counter-insurgency and reconstruction effort in the province, it may well be an enduring one.
  • 170 (Infrastructure Support) Group RE is always recruiting across the engineering spectrum and is interested in new recruits with or without military experience. Please see website for further details.

Author affiliation

Steve Matthews is an Engineering Geologist working for a specialist minerals and mining consultancy, and is also a TA officer.