GB2615860A

GB2615860A - Water extraction

Info

Publication number: GB2615860A
Application number: GB2218801.5A
Authority: GB
Inventors: Cutting William
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-01-28
Filing date: 2022-12-14
Publication date: 2023-08-23
Also published as: GB202218801D0; GB202201213D0

Abstract

The invention relates to a method of river water abstraction from a final weir, or a tidal interface (between fresh water and salt water). A new water abstraction station or facility may be built at the weir or at the tidal interface. If a new facility is provided, then the method can involve decommissioning or removing an upstream river water abstraction facility. This can make available the maximum amount of fresh water from a UK river, which will solve water shortages in the UK. The water can then be screened, filtered and/or cleaned, once abstracted, and so can be pumped to a water treatment works to be made suitable for use in a public water supply. The invention also relates to river that has a water abstraction facility at a final weir, or at a tidal interface, as well as a river abstraction station located at the final weir or the tidal interface.

Description

Water Extraction This invention relates to a way of relocating river water abstraction, in particular moving a (fresh) water intake(s) adjacent to, or very close to, the final weir, a position where, by using the terms of the EU Water Framework Directive, maximum use can be made of river water currently allowed to flow out to sea. This can provide additional water to meet the current demand and predicted water shortfall.

Background to the Invention

The current average daily demand for water in England and Wales is approximately 15,000 Megalitres per day (1 Megalitre = 1 million litres).

The present abstraction strategy cannot meet this demand on a continuous basis and so water companies have been forced to impose occasional water use restrictions.

Population growth, regulatory changes and global warming are predicted to increase water demand by a further 4,000 Megalitres per day. This cannot be met using the current strategy.

The majority of the water comes from underground aquifers, and these are now over committed. The various environmental regulators are seeking reductions in the abstraction of water from these sources.

The remaining natural source of water is the nation's rivers. The current abstraction strategy restricts the timing and the amount of water that can be taken. Abstractions must be balanced by the requirement to maintain flow in the river.

The result is that present resources cannot meet present demand without expensive impounding reservoirs or high energy use schemes such as salt-water desalination or sewage works effluent recycling or extensive water transfer. The predicted increased demand CAN only be met using the above schemes, using massive amounts of electricity and, by association, emitting hundreds of thousands of tonnes of carbon dioxide into the atmosphere every year.

Regulatory Position As can be seen in Figure 1, rivers have two basic sections. The upper river (inland water) contains the freshwater making its way to the estuary (or transient water), where the freshwater mixes with sea water, as it makes its way to the sea. Reductions in the flows in these two separate sections (are) regulated as below.

A) Freshwater Section -Inland waters Regulated by the Water Resources Act1991, Section 21 Section 21 of the Water Resources Act 1991 gives the Environment Agency the necessary powers to control the amount of water allowed to be abstracted from the freshwater section of a river, referred to as inland waters.

Abstractions from rivers must be balanced by the need to retain sufficient flow in the freshwater section in order to protect and maintain the sometimes quite delicate ecology.

For each river in England, the Environment Agency has established a Catchment Abstraction Management Strategy (CAMS) which controls the amount of water that can be taken from the inland water and introduces a ban on abstraction during low flow periods. As part of the CAMS the Environment Agency has set a Minimum Residual Flow (MRF). When the flow falls below this MRF all abstractions must cease and rivers enter what is referred to as a 'Hands off Flow' period. This significantly reduces the quantity of water available for public water supply.

B Estuary or transient waters This is also shown in Figure 1. Reduction of flow of fresh water into the river estuary is regulated by the European Union Water Framework Directive.

Although the UK is no longer part of the European Union, the terms of the European Water Framework Directive are still the basis of regulation in the British Water Industry. The terms of the Directive have been interpreted for use in United Kingdom by the United Kingdom Technical Advisory Group (UKTAG) and released in the report Environmental Standards and Conditions.

The regulations and methodology are set out in the Chapter headed 'Impact on Estuaries of the Abstraction of Freshwater Flow' (page 50 onwards).

This Chapter sets out the methodology for establishing the allowed percentage reduction of freshwater flow into the estuary by setting condition limits based on the condition and sensitivity of the estuary.

Tables 27 to 29 of page 54 (attached) show those condition limits to be somewhere between 20% and 80% of all natural flows (On). There are no 'Hands off Flow' periods.

Observations A) Freshwater section The MRF is determined for each individual river and can vary from around the 65%ile flow up to the 50%ile flow. This means the CAMS can introduce a 'hands off period lasting for up to half the year. A water company that relies on taking water from the river has to supply water for 100 per cent of the time, and therefore has to make alternative arrangements.

These are usually large and expensive reservoirs that store water during high flow periods. As water treatment works properly function at a constant rate the yield from rivers subject to an MRF is limited to the yield of the reservoir. This yield can be as little as 50% of the yield that would be available with constant abstraction directly from a river. Reservoirs are expensive to construct, use large amounts of energy and by association emit large quantities of carbon dioxide into the atmosphere.

The most recent draft water resources plans are showing the effect of the CAMS. Almost all companies in the water stressed regions are reporting the need to find-alternate resources other than their local aquifers or rivers. These include salt-water desalination, wastewater recycling and long-distance bulk supply transfer. As with reservoirs, these are all very expensive to construct, use huge amounts of power to operate and by association emit hundreds of thousands of tonnes of carbon dioxide into the atmosphere every year.

This approach is in direct contravention of the Paris Agreement on carbon reduction and the results of C0P26 meeting and the Government zero carbon target. It is essential to find a solution to this problem.

B Estuary or Transitional Waters Tables 27 to 29 of the UKTAG report (copy attached) show that the flow of freshwater into a saline estuary can be reduced by a percentage dependent upon the status and sensitivity of the estuary. This reduction can be made to any flow and therefore with correct positioning of the abstraction point, there is no 'hands off' period. With an abstraction point situated adjacent to or very close to the final weir or tidal interface, the annual daily yield from the river is equal to the percentage reduction stated in the UKTAG tables attached.

The natural rate of flow into an estuary is determined by using the Wallingford HydroSolutions2020, Low Flow Enterprise Software and is designated On. The number attached i.e. QN95 relates to a natural flow that is exceeded by 95% of all recorded flows.

The vast majority of coastal and estuarine waters in England are designated 'moderate status' as shown on the Environment Agency Ecological Status Maps. The majority, if not all river estuaries in England are rias or drowned valleys. This gives a very large volume of water at high tide and at Qn95 flow they are designated as Low Sensitivity.

Nationally, calculations show that at Qn95, approximately 23,000 Megalitres per day of useable freshwater that flows into the sea. Using the Tables on Page 54 of the Report, this could be continuously reduced by 50% (i.e.,11,500 megalitres per day) and, following the introduction of the terms of this invention, could be available for water supply. This quantity is far in excess of the predicted shortfall.

Conclusion

The water companies abstract water from the aquifers and upper reaches of river catchments and are regulated by the restrictive terms of the Water Resources Act. To meet any increase in demand they must use schemes which use very large amounts of electricity, and which will, by association, cause the emission of hundreds of thousands of tonnes of carbon dioxide every year.

This is in direct opposition to Government zero carbon targets, The Paris Agreement, and the results of C0P26.

These schemes will be far more expensive than existing ones and will cause an increase in customer charges. This is directly opposed to the objectives of the Water Industry economic regulator, Ofwat As these schemes are so costly, water companies will continue to abstract the maximum quantities from the upper river catchments. There will be no reduction in current perceived level of damage; there will be no improvement in the aquatic ecology.

One object of the present invention is to seek to mitigate, or overcome, one or more, or all, of these difficulties and problems and to seek to create conditions to enable the regeneration of the aquatic environment.

Summary of the Invention

The invention therefore relates, in a first aspect, to a method of water abstraction (or extraction, or capture, the terms are used interchangeably), from a river, the method comprising: abstracting (or extracting or capturing) river water, using an abstraction point that is adjacent to, near or very close to: a) a final weir; b) a tidal interface, such as the interface in a river between fresh water and saline or salt water; and/or c) a location where there is a constant (water) level and variable (water) level such as at a final weir.

Preferably the extraction is in the freshwater section of the river adjacent to or very close to the final weir. Any abstraction upstream from that point may be subject to the CAMS "hands off flow requirements.

Suitably, the water abstracted is fresh water. The extraction will preferably be at an abstraction station or facility.

Suitably, the water so abstracted can then be screened, filtered and/or cleaned.

In this specification, the term "weir" usually refers to a barrier (or a dam) located across a river, in order to alter or control the flow of (river water). Usually in weirs upstream water runs over the weir, and so overflows, this being the main difference to a dam.

Suitably, the extraction facility or station comprises one or more pumps, in order to pump or transfer the (river) water.

A second aspect of the invention relates to a river, which comprises a water abstraction station or facility, adjacent, near or very close to: a) a final weir; or b) a tidal interface, such as the interface in a river between fresh water and saline or salt water; and/or c) a location where there is a constant level and variable level in the river, for example a weir.

A third aspect of the invention relates to a river (water) abstraction (or abstraction or capture) station (or facility) that is located adjacent, near or very close to: a) a final weir; b) a (tidal) interface, such as an interface between fresh water and salt water (such as saline); or a location where there is a constant level and variable level in the river, for example a weir. Usually the station (or facility) will be located at, or adjacent to, the final weir.

The abstraction facility may have one or more pumps. It may have one or more screening, filtering and or cleaning means. This may allow the water so abstracted to be suitable for pumping to a water treatment plant where it can be made suitable for use in the public water supply.

The first aspect more particularly relates to a method of making the most efficient and effective use of the water flowing in a river. Thus, according to the invention, a method can comprise: a) decommissioning (or removing) an (existing) upstream river water abstraction point(s) or facility b) capturing (or abstract, intake or extract) a (requisite or desired) amount of(river) water at, or near, the final weir or the tidal interface; c) such as by using an intake (abstraction or extraction) structure and/or facility associated with, or close to, or adjacent to a final weir; d) optionally, transferring the (river) water (so abstracted) to a water treatment works or other destination; and e) optionally, adjusting the operation of other water resources to make the most efficient use of water in the environment.

The invention may thus provide a method of making available the maximum allowable quantity of freshwater from rivers in the UK. This may(will) help meet the present and predicted water shortages in the UK and to make it unnecessary for the use of schemes which use large quantities of electricity.

The invention may thus comprise: a) constructing a new river water abstraction facility (e.g. point A) adjacent to or very close to the final weir and/or suitably located at the interface between the freshwater and saline section of the river; b) optionally, constructing a water screen plant, e.g. as part of the abstraction point, such as comprising fixed trash bars C and/or moving self-cleaning screens D; c) optionally, install pump(s),(see F), suitable to pump the (screened) water to a desired destination, such as: -i. to an existing water treatment plant.

H. to a new water treatment plant; and/or iii. to a point upstream of the existing water abstraction point; d) optionally, install delivery pipe (see G); e) optionally, install meter (see H).

When the water abstraction facility or point is constructed or located adjacent to or very close to the final weir, it may be capable of abstracting the maximum quantity allowed, for example under the terms of the European Union Water Framework Directive. The (abstracted) water may be passed to a water treatment works, such as for use in a public water supply.

The invention thus relates to a method of abstracting the maximum quantity of water from the freshwater section of a river at a point where it is regulated by the terms of the United Kingdom Technical Advisory Group report Environmental Standards and Conditions, the interpretation of the European Union Water Framework Directive into UK regulation.

One aspect relates to a method of establishing the maximum quantity of water that can be abstracted at the abstraction point adjacent to the final weir/tidal interface using the natural rates of flow established by Wallingford HydroSolutions2020 using their Low Flows Enterprise Software.

The method can comprise screening, filtering and/or cleaning the(river) water so abstracted (or extracted or captured the terms are used interchangeably), such as to make it suitable for pumping.

The method can comprise pumping the (river) water so captured to an.existing water treatment works, to thus render it suitable for use in public water supply.

The method can comprise pumping the water captured to a newly constructed water treatment plant, thus to render it suitable for use in public water supply.

The method can comprise pumping the water so captured such as to a discharge point in the river upstream of anexisting abstraction point (or station or facility). This may increase allowable abstraction from the existing abstraction point and/or for transferring that water to an.existing water treatment works, such as for use in public water supply.

The method can also comprise measuring the quantity of (fresh)water abstracted at the (new) abstraction point (adjacent to or very close to the final weir/tidal interface), such as by means of a suitable water meter.

The method can also comprise decommissioning and/or removing the prior existing intake, especially where it is (then) surplus to requirements.

The method may reduce the quantity of electricity used by the water industry, for example to meet current and predicted future demands.

The method can result in assisting the water industry to meet the government zero carbon target.

The method thus aims to reduce predicted future increases in customer charges.

Abstraction from inland waters can require expensive works to make it continuous, e.g. reservoirs, aqueducts, etc. Since the abstraction at the final weir can be made continuous (e.g. below 95%ile) no expensive reservoirs may be required. This means that abstraction can be cheaper and can occur on, or from, smaller rivers.

Smaller rivers can be more widely spread so small (e.g. 5MI/day) (abstraction)(water)works can be built, rather than pump water from a distance.

The method can reduce the over-abstraction of water from underground aquifers enabling the environment to be improved.

In the accompanying drawings: Figure 1 shows a river with the freshwater/saline interface (the preferred site of extraction in the invention); Figure 2 shows an existing river (prior art) with an existing abstraction point upstream (X) and a final weir (the site of extraction in the invention); Figures 3 to 5 show a new abstraction facility according to the invention; and Figures 6 to 8 show 3 preferred ways (in the invention) of processing abstracted river water.

The invention will now be described by way of example, which is purely illustrative and not intended to be limiting.

EXAMPLE

A new abstraction point A is constructed as an extension of final weir Y -as shown in Figure 3. This intake works intercepts the requisite percentage of the Qn95 flow determined by Wallingford HydroSolutions 2020 using their Low Flows Enterprise Software.

The remaining water is allowed to flow over final weir Y and enter the estuary, as shown in Figure 4.

The requisite percentage to be intercepted will be determined using the Appropriate Table on page 54 of the United Kingdom Technical Advisory Group Report -Environmental standards and Conditions, having calculated the status and sensitivity of the estuary/transient water.

The intercepted water will pass through a trash rack/side weir C and an automatically cleaned screen D before entering the pump chamber E (see Figure 5).

The pump(s)F will deliver the water into the delivery pipe G passing through meter.H The meter will register the amount abstracted which will not exceed the percentage of 0n95 described above (see Figure 3).

The pipeline G will transfer the water to:-1.An existing water treatment works.

In this scenario the existing abstraction pointX will be abandoned and all water for the scheme will be abstracted at new abstraction point A (see Figure 6).

2.A new water treatment works It may be more efficient and economical to construct a new water treatment works close to the new abstraction point A. Some lower river treatment plants are too far upstream to economically accept the flow.

The existing intake will be decommissioned (see Figure 7). 3. A discharge into the river above the existing intake This scenario will exist where the water company is still able to abstract some water at intake X but requires additional yield. This can be achieved by taking the water from new abstraction point A and discharging it into the river, upstream of intake P. This additional water will then be abstracted at intake X together with the remaining allowable abstraction in accordance with the terms of the abstraction licence (see Figure 8).

Claims

Claims 1 A method of water abstraction from a river, a method comprising abstracting (river) water at, adjacent to, near or very close to an abstraction point which is: a. a final weir; and/or b. a tidal interface.
2. A method according to claim 1 wherein the river water is captured, extracted or intercepted.
3 A method according to claim 1 or 2 wherein the (tidal) interface in the river is between fresh water and salt water (saline).
4. A method according to any preceding claim wherein only) fresh water is abstracted.
5. A method according to any preceding claim wherein the water is abstracted by a water abstraction station or facility.
6. A method according to claim 5 wherein the abstraction facility or station comprises at least one (water) pump.
7 A method according to any preceding claim which additionally comprises decommissioning or removing an (e.g. existing) river water extraction facility that is upstream of the abstraction point.
8. A method according to any preceding claim which additionally comprises transferring the (river) water to a water treatment works.
9. A method according to any preceding claim which additionally comprises screening, filtering and/or cleaning the so abstracted (river) water.
10.A method according to any preceding claim wherein the abstracted (river) water is pumped to: a An existing water treatment works; b A newly constructed water treatment facility or station; or c. A discharge point in the river upstream of the abstraction point.
11. A river comprising a (river water) extraction station or facility that is adjacent to, or near: a. A final weir; or b. A tidal interface.
12. A river according to claim 11 wherein the (tidal) interface is between fresh water and salt water (saline).
13.A river according to claim 11 or 12 wherein the interface is between inland water and an estuary.
14.A river (water) abstraction facility or station which is located at, adjacent to, or very close to: a. A final weir; or b. A (tidal) interface.
15.A water abstraction station according to claim 14 which comprises one or more pumps.
16.A water abstraction station according to claim 14 or 15 which additionally comprises means to transfer (so abstracted) water to an existing water treatment works or plant, a newly constructed water treatment or plant, or a discharge point of the river upstream of the abstraction facility.
17.A water abstraction station according to any of claims 14 to 16 which additionally comprises water volume measuring means, for example a meter, suitably capable of measuring the amount of water abstracted from the river.