WATER MANAGEMENT FAQ’S

Part 1: Issued 17/02/2012 http://www.waterscape.com/features-and-articles/features/water-management-faqs

Managing the water in a 200-year-old canal system throws up lots of challenges, particularly in a dry year. British Waterways’ water management team are often asked questions about their work by boaters or members of the public. Here, they’ve collected some of the most common questions and explained the answers. If you have any further questions on water management or drought mitigation, please feel free to post them in the comments. The water management team will either respond to them directly, or include them in future FAQs.

How much water is there in a lock? The volume of water used in the operation of a broad lock is roughly 0.24 megalitres (240,000 litres, or more nearly 53,000 gallons). In a narrow lock this figure is about 0.14 megalitres (140,000 litres or 31,000 gallons).

How many lock operations are there in a year, week or day? This varies across the network and some locks are obviously busier than others. Braunston, at the heart of the network, sees around 6,000 lock operations each year. The average figure for locks across the South East is in the region of 4,000 lock operations. In comparison, locks in the Kennet & Avon region average around 2,300 lock operations per year. BW produces an Annual Lockage Report every January/February, detailing lockage for the previous year, which is available for download on the BW website.

At the peak of summer, a popular lock may see in the region of 230 lockages per week (or 33 lock operations a day). A maximum of six lock operations is the most you could feasibly expect in one hour - ten minutes for each passage through a lock.

Do pumping stations operate all year round? Pumping stations don’t generally operate outside of the main boating season as demands are low and the canal pounds are mostly fed by surface water inflows. Throughout the boating season, pumps are generally automated – they kick in when sensors detect that water levels need topping up.

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What rate do the pumps work at? They are all different, but, for example, pumps at Hillmorton on the North Oxford Canal can move 17 megalitres per day (17,300,000 litres or 3,800,000 gallons per day). That’s more than 120 narrow locks of water.

On the Kennet & Avon Canal near Bath, the Claverton pumps abstract up to 36 megalitres per day (36,000,000 litres or 8,000,000 gallons per day). A chain of backpumps recirculate lockage water, and transfer water from the River Avon up to the Summit pound to meet canal demands.

Why don’t pumping stations operate all the time? There are a few reasons why pumping stations cannot operate all the time. Before we go through them it may help to explain that pumps have a number of roles – to take water from neighbouring rivers and groundwater sources; to recirculate water displaced during lock operations; and, in some cases, to transfer water from one pound to another.

In the case of taking water from rivers, it is important to bear in mind that, under Environment Agency regulations, we are only able to do so when the rivers have enough water in them. For example, the three pumps at the River Tove (that feeds into the Grand Union Canal north of Milton Keynes) have a total capacity of 19 megalitres per day, but we are restricted in periods of low river flows to only 4 megalitres per day. Similarly Hillmorton pumps water from the River Swift up to the Braunston Pound where it can then be pumped up to the South Oxford Summit by the Napton pumps. However, in drought conditions the volume of water abstracted from the River Swift reduces and therefore the frequency with which the pumps operate reduces.

Pumping stations can’t instantly recirculate water displaced through lock operations as, at peak times, they simply can’t keep up. Therefore the water level in upstream pounds may gradually fall and downstream pounds may rise during the course of a busy day.

We’re continually monitoring the operational settings of our pumping stations to make sure they work as efficiently as possible. In the long term, we are planning to introduce more ‘intelligent’ pumping controls that dynamically control pound levels by concentrating pumping outside of times of peak demand, rather than reactively responding to lockage demands.

How do you deal with broken pumping stations? Where possible we plan pump maintenance and downtime outside the main boating season. However, if a pumping station has a fault during the boating season we will try to get it back up and running as quickly as possible. In an ideal world we would have a spare pump for each site but, as each is so different, it just isn’t practical for us to do that. Some pump stations have a standby pump which can be used if the main pump has a problem. Sadly this doesn’t mean that we can run both pumps together, as the connecting pipework will only be big enough to take the flow from one of the pumps.

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Why don’t you add more pumping stations or increase pump capacities when there is a drought? Pumping stations exist at locations where it strategically makes sense to have them for recirculating or transferring water. Many pumping stations in the South East were introduced at key locations during the mid-1990s, following regular droughts and water shortages. Initially these were temporary pumps designed to deal with an immediate drought problem, but they have since been converted into permanent installations. At some locations it wouldn’t make sense to have pumps. For example it isn’t worth having a backpump at Foxton, as this would deplete water to the GU North, or recirculate water south from the South Oxford Summit which isn’t a feasible option.

The Hatton Flight has no backpumping and therefore water always flows to waste in Leamington. Why are you not transferring this water up the Radford to Calcutt Flight? Our aim is to operate the canal as efficiently as possible to minimise water demands. However, there will always be residual terminal flows in certain trough pounds, such as at Leamington. Pumping trials and data that we have collected from our telemetry system shows that we are successfully recirculating lockage water along Radford to Calcutt. However, for a number of reasons (other than the capacity of the pumps) achieving an actual net transfer of water from Leamington is difficult. The ‘hydraulic’ capacity of the flight to transfer water is restricted by short pounds with limited freeboard. A solution to this issue (involving longer rising mains bypassing multiple locks) has been investigated but, at the moment, it is disproportionately expensive for the water resources gain.

Why don’t you fix all your leaking lock gates? The majority of water lost from the canal is through seepage and evaporation. The canal network is more than 200 years old and largely features a clay-lined canal bed which is not 100% watertight. While we have more water travelling through some locks than we would like, most of it remains within the canal system to feed demand lower down. In these cases, the lock leakage simply allows water to pass downstream, which is water that we would otherwise have had to feed via sluices and bypass weirs.

This winter we are spending over £20m across the network on a wide range of maintenance works, with an additional £10m of construction works coming from third party funding. As part of this maintenance over 200 lock gates are being replaced.

What did the restrictions during the summer of 2011 actually achieve? The weather last year was extremely dry. As the main boating season progressed, it became clear that the drought would have a significant impact on canal water resources. We have estimated that had the restrictions not been implemented a full closure of navigation would have occurred across much of the Grand Union Mainline, GU North and the Oxford Canal by the end of August. Therefore restrictions were introduced which had the following aims:  They reduced demands by discouraging boat usage from areas most at risk (i.e. the Leicester Line and GU North, served by Naseby, Welford, Sulby and Saddington Reservoirs).  Limited operating hours enabled more effective recirculation of lockage and efficient supply of water around the ‘hydrological unit’ via backpumping

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 By concentrating lockage to peak times, boaters were encouraged to share locks and make the most efficient use of water.

Do restrictions simply concentrate the same lock usage (and hence water use) into a shorter period? No, our experience and monitoring of lock usage shows that the restrictions led to decreases in lock usage. The decrease depended on the location and the nature of the restriction. Areas seeing lockage restricted to 10am-2pm typically saw a reduction in daily lockage of 20%. The Foxton Flight, where essential movements only were allowed 10am-2pm saw a reduction in daily lockage of up to 40%.

Given that reservoirs are so low, what are you doing to prepare for next season? In addition to the annual winter stoppage programme, £700,000 is being spent on vital drought mitigation works in the Midlands and South East to try and conserve as much water as possible. The schemes include clearing canal feeders, pumping and transferring additional water into our reservoirs, installing additional monitoring equipment to allow existing backpumps to be used more effectively, accelerating existing major works projects to deliver in time for the main boating season and relining a number of leaking lock gates in the worst affected areas to reduce demands for water.

We are also engaging with boating user groups and trade at an early stage to make them aware of what they can do to help.

Where can I find out about the water resource situation? Waterscape is a great source of information on the latest water resource position and any boating advice/restrictions. Our hydrology team produces a monthly reservoir watch on waterscape, which gives details of reservoir holdings across the BW network. Or you can contact your local office to subscribe to notifications in a particular area.

Can I do anything to help? BW is seeking volunteers to help with a variety of tasks. Volunteer Lock Keepers were trialled successfully on some waterways in 2011. This year we are looking to expand the number of volunteer lock keepers as they can have a direct, positive influence on the efficient passage of boats around the network.

Find out more about becoming a volunteer lock keeper.

Why don’t you operate pounds brimming with water as the longer pounds could operate as a reservoir? The loss of water from a canal pound due to leakage and seepage is the largest component of water demand on a canal system. Loss rates are at their highest during the summer, when soil is dry and water tables are low. The leakiest part of the canal lining is the top 15 cm (6 inches), because it is continually wetted and dried. It is also subject to holes or cracks formed by burrowing animals and wave action from propellers. So increasing the operational level of a pound, especially

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in a drought, would greatly increase loss rates. During a drought, we actually aim to run pounds as low as operationally possible to reduce loss.

Why don’t you dredge reservoirs to increase their capacity? We have a rolling programme of surveys to monitor the capacity of our reservoirs and these show that, generally, over a number of years siltation hasn’t been a significant problem. It is also generally accepted within the water industry that the removal of silt from reservoirs is considerably more expensive than creating new resources or reducing demand elsewhere. This cost means that reservoir dredging is very rarely feasible and, particularly so in this case given the results of our reservoir monitoring.

What are you doing to ensure water restrictions or stoppages aren’t needed in the future? As well as responding to unfolding droughts, we also take a more strategic approach to managing future water resources. Our water management team is responsible for assessing the resilience of water supply and advising waterway units and BW directors on the potential impact of proposed canal developments (e.g. new marinas) and investment required to supplement water resources. BW reserves the right to object to or decline canal development proposals on the basis that they may have an unacceptable impact on the existing water supply. Unfortunately, we can never give absolute assurances to our customers about having enough water to get through every drought, regardless of the extent, duration and severity but we will do whatever we can to keep as much of the network as possible open.

How can boaters help to save water? Boaters have an important role to play in water management. You can help us by:  Sharing locks where possible and making the best use of the water available.  Make sure paddles are fully closed once you’ve passed through a lock.  Aim for minimal contact when navigating through locks by ensuring gates are fully open as you pass through. Even a single boat in a broad lock should open both gates whilst moving through. Pushing gates open using a boat can damage the gate lining, increasing its leakage. We request that marina owners, particularly those with hire fleets, help encourage boaters to act responsibly with water. We also need all canal users to be vigilant about vandalism, as we have had some huge water wastages this year through vandalism. Please call the police if you have any concerns or witness vandalism.

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Draft Part 2: Awaiting publication on Waterscape

What has your additional investment in drought schemes achieved? So far, we managed to completely refill three reservoirs with temporary pumping, plus increase the water stored in three others. We’ve installed new monitoring on some of our pumps to get better water control and recirculation of water as we go into the Easter period, and we’ve improved the flow in a number of feeders that supply the canals by cleaning the silt and vegetation from these. We’ve installed and tested new backpumps at Braunston Locks on the Grand Union Canal (which will run on generators until we get a mains power supply installed) and we’re just about to finish lock relining works on the Grand Union Canal north of Foxton Locks, to reduce leakage along this section.

What is the potential ecological impact of the drought on the canal network? We are taking action now to conserve water levels in the canals where possible and so protect our wildlife. We will be monitoring conditions in affected areas because low flows coupled with higher temperatures as we move into spring and summer can cause problems such as algal blooms and low oxygen in the water. We will do everything we can to maintain suitable conditions, but the longer the drought goes on the harder this will be so where we can’t we will endeavour to carry out fish rescues to recover fish into areas we can protect.

What are you doing to help boaters whilst restrictions are in place? We’re helping boaters to plan their journeys by publishing maps showing the restrictions and the differing risk to navigation across the network. These maps will be updated on a monthly basis giving boaters up-to-date information to help them plan their route. The maps will be displayed on noticeboards across the affected areas and can be downloaded from the Waterscape Reservoir Watch page.

Why don’t you fix all the leaks on the network? We consider leakage as one factor in our asset inspection procedures, which help us to prioritise future works. The canal network is a 200 year old system, and the quality/integrity of the lining to prevent leaks varies across the network. In some locations, it has been cost effective to address the leakage by relining whole lengths of canal, in others it may be specific structures (such as locks or culverts) that have high loss rates. Sometimes, it is more cost effective to develop additional water resources (identify alternative sources of water) rather than tackle the most expensive leaks, especially when you consider that relining one kilometre of canal can cost £1million.

With all this talk about drought in the south-east, what are you doing to help the water companies transfer water from the “wet” north to the “dry” south – a canal watergrid? Moving water short distances is certainly possible and canals can play their part in doing that. Because water is heavy, moving it longer distances is more challenging, however we are open to the concept and it would be another use for the nation’s 200 year old canals and rivers. We already transfer water relatively short distances along a number of our canals, which is then used for industry, agriculture and public water supply. We have been in discussions with a number of water companies to see where it is possible for our canals to act as transfer routes to support public water supply this year, or over the winter of 2012/13 and beyond if the dry conditions persist.

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Although you’re spending money this year, why did you not have money to spend on the Leeds & Liverpool Canal in 2010 when drought led to closure of the canal? Although ultimately driven by a lack of rainfall, all periods of drought are different and affect water supply in different ways. The problems that impacted on the Leeds & Liverpool in 2010 were caused by a reasonably short duration of extremely dry weather. There was enough rainfall over the winter of 2009 into 2010 to completely refill reservoirs ready for the start of the boating season. However, an extremely dry end to the winter through to the middle of the summer reduced the soil moisture content rapidly. This reduced inflows into reservoirs prompting water supplies to drop much quicker than we’d usually experience. In the longer term, we have investment plans to try to increase the reliability of this canal and reduce the likelihood of this type of situation in the future. In contrast, the drought situation in 2011 and into 2012 being experienced across the southern half of England has been caused by a much longer dry period. For well over a year now monthly rainfall totals have either been well below average or below average for the time of year. The effect of the low rainfall has caused many rivers and streams to be at record lows for this time of year. This situation hasn’t just been problematic to the refill of our reservoirs - seven water companies in the south and east of England have announced hosepipe bans and the Environment Agency has restricted farmers from abstracting water from rivers in some locations. However, as we could see this situation worsening over a period of time, we had the opportunity to implement a number of drought schemes to improve winter refill as much as was practically possible.

I’m a boater, how do the hosepipe bans coming into force affect me? Seven water companies have brought in temporary use bans (often called hosepipe bans) to reduce consumption of drinking water supplies and prolong the available water for as long as possible. Each company has slightly different rules in terms of the uses they have banned, so it is best to check their websites for detail. In general though, none of the bans being put in place will stop you from using a hosepipe to fill the water tanks on a boat, but they do prohibit washing a private leisure boat using a hosepipe.

Does the drought affect use of water points and sanitary stations? Although the water company temporary use bans still allow you to fill water tanks on a boat, it is important for everyone in the affected areas to try to reduce consumption of water, whether this is tap water at water points or sanitary stations, or the use of canal water for lock usage.