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KENT
Campaign to Protect Rural England The Campaign to Protect Rural England exists to promote the beauty, tranquillity and diversity of rural England by encouraging the sustainable use of land and other natural resources in town and country. We promote a positive long-term future for the countryside — one which values its natural and built environment. Our Patron is Her Majesty the Queen. We have 60,000 supporters, a branch in every county, nine regional groups, more than 200 local groups and a national office in London. CPRE is a powerful combination of effective local action and strong national campaigning. Our President is Sir Max Hastings.
CPRE Kent is the charity’s largest county group, with more than 3,000 supporters, 12 district groups and three special-interest groups, which focus on housing, transport and environment.
CPRE Kent, 3 Evegate Park Barn, Station Road, Smeeth, Ashford, Kent TN25 6SX. 01303 815180 [email protected] www.cprekent.org.uk
CPRE Kent is a company limited by guarantee, registered in England, number 4335730 Registered charity number 1092012
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A Water Resource Strategy for Kent>>
KENT A Water Resource Strategy for Kent
By Graham Warren
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A Water Resource Strategy for Kent>> Contents
Chapter Page
1 Introduction 8 2 Kent’s Water Resources: Gains and Losses 9 3 Managing Kent’s Water: The Story so Far 26 4 Future Needs: Where do we go from here? 33 5 The Water Company Perspective 39 6 Planning for Growth: A CPRE Strategy 42 7 Summary and Conclusions 49 Tables
1 Annual Water Abstraction in Kent Area 2003 18 2 Public Water Supply in the Kent Area 20 3 Reservoirs in the Kent Area 21
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A Water Resource Strategy for Kent>> Contents
Figures Page
1 The Water Cycle 10 2 Catchment Areas and County Boundary 11 3 Mean Annual Rainfall: Standard Average 1961-90 12 4 River Flow Measurement Stations 14 5 Seasonal Flow Variations 14 6 Major Aquifers 16 7 Actual Average Year Usage 19 8 Water Company Supply Areas 20 9 Water Balance Assessments 23 10 Comparison of Resource Balances for Average Year and Drought Year 24 Conditions 11 Resource Assessments and Resource Availablity Status 32 12 National Water Resource Assessment 34 13 SE Plan for Kent, Demand Growth for Plan Period withWater Company Source Development Options 40 14 Domestic Use Components 44 15 Demand Growth for Plan Period with CPRE Resource Management Options 47 16 CPRE Kent Strategy: Suggested Scheme Implementation 50 Appendices
1 Climate Change Indicators 55 2 Building Research Establishment Guidance on Domestic Potable Water Use 57 3 Summary of Representation by CPRE: Margate and Broadstairs 58 Wastewater Treatment Scheme SWS; August 2004
Glossary 52
References 54
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A Water Resource Strategy for Kent>> Foreword
CPRE Kent — the Kent branch of the Campaign to Protect Rural England — has been campaigning to improve the decisions that affect our environment for nearly 80 years. We have helped to shape a planning system which has enabled our densely populated country to retain so much of its beautiful, diverse countryside. As we go to press, the Garden of England has been in the grips of a drought that has lasted for two winters. Hosepipe bans are restricting water use across the whole county and the spectre of far more severe restrictions looms large. Not since 1921 have we faced such a critical water shortage. We know, now, that we must all play our part in using water wisely and well if we are to meet the demands of the existing population. But what of the extra pressure placed on the county’s water resources from the 20% increase in households planned for Kent and Medway over the next 20 years? The water companies assure us that they will be able to meet this demand. Regional planners appear to share this confidence, claiming that with water-saving measures built into every house, and new reservoirs, we will have more than enough water to supply our region’s needs in 20 years’ time. But in CPRE Kent we do not share this optimism. House builders are making woefully poor progress in delivering new homes built with water efficiency in mind — even in the growth areas of Ashford and the Thames Gateway. And while new reservoirs — or expanding those that we already have — may help to meet the demand, we have struggled to keep our existing reservoirs full over the last two winters. There are many who would argue that perhaps we are worrying unnecessarily over a situation that is only temporary; after all, the last two winters have been unusually dry. Unfortunately, the reality is that even in years of average rainfall Kent already uses a huge proportion of its naturally available water to meet the demands of its public supply. There is very little slack in the system for those years which are drier than average. So any significant, long-term increase in demand simply cannot be met from additional abstraction from our traditional sources. Indeed, unless we can address the existing high levels of use we will struggle to continue to meet the water demands of Kent and Medway’s current population, let alone those of the 20% additional households proposed in the name of sustainable development. We hope that our strategy will help inform the debate over Kent’s future housing growth and water supply, in the face of rising demand and the uncertainties of climate change. And we fervently hope that the future of Kent truly is a sustainable one.
Hilary Newport Director, CPRE Kent May 2006
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A Water Resource Strategy for Kent>> 1 Introduction
1.1 Having just experienced a winter of hosepipe bans, Kent's consumers now face the prospect of a summer of increasingly severe restrictions, imposed by the water companies in their efforts to alleviate the worst effects of a drought caused by two successive winters of below-average rainfall. Underlying the recent acute shortage, however, is a more problematic long-term decline in the balance of supply and demand. This has now reached the stage where the county’s water resources have been classified by the Environment Agency (EA) as unsustainable (Ref 1). CPRE Kent believes that unless action is taken to address the deficit as a matter of urgency, the water companies will be unable to keep pace with the steep increase in demand caused by housing growth (122,000 new units in Kent by 2026), climate change and the need for a greater share of the resource to be reserved for the improvement of river flows and wetland levels in line with new European environmental quality targets (Ref 2).
1.2 In the past 100 years, demand for water for all uses has increased almost ten-fold. Groundwater abstraction in North Kent during the early 1900s represented about 10% of the effective rainfall, but today it accounts for nearly all of it. This has had long-term consequences for river and wetland habitats. (As evidence of this, we have seen the loss of the perennial spring-fed streams which once supported thriving commercial watercress beds and trout fisheries.) At the same time as trying to balance demand against diminishing resources, we need to give increasing attention to improving the water environment. To achieve this will require a substantial part of the annual water resource being reserved solely to sustain our spring-fed streams and wetlands. The overriding need to restore a sustainable balance has meant that some aquifers have been declared as more or less “off limits” for any further increases in abstraction — this applies to all high-consumption uses, including irrigation and public supply.
1.3 The water companies seem confident that they have the solutions and will be able to meet the new challenges. CPRE Kent does not agree. We have attempted to make clear our concerns, drawing what lessons we can from the history of water use and management in Kent in a forecast of the likely trend in the balance of supply and demand over the next 20 years. From what we know of the companies’ general intentions for addressing future demand growth, we have had to conclude that few of the options so far included in their business plans are likely to have the makings of a coherent and effective action plan. It is for this reason that we have been prompted to put forward our own, alternative long-term strategy, one which we believe consists of viable engineering solutions and provides a cost- effective and environmentally sustainable way forward for Kent. It requires, however, a fairly radical shift in our approach to the use of our dwindling resources. And time is not on our side if we are to spare ourselves more decades of crisis management.
1.4 CPRE Kent’s strategy puts a special emphasis on the conservation, re-use and reallocation of our existing water resources, with correspondingly less reliance on the further development of groundwater and reservoir-based sources of supply. The EA is currently engaged in the preparatory work for a new water resource strategy for England and Wales, and we would commend our proposals for consideration in the assessment of options for the South East.
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A Water Resource Strategy for Kent>> 2 Kent’s water resources – gains and losses
2.1 Our rivers and aquifers are vital elements of the natural environment with its rich biodiversity and recreational value. Their continued survival depends, for the most part, on how prudently we manage and regulate water abstraction and consumption, for whatever purpose, particularly in times of drought when demand is high. Just how much importance the community attaches to this principle has determined the policies and strategies that have evolved over the years in our efforts to reconcile the competing demands for water supply and environmental sustainability. Management of a water resource is essentially a matter of good house-keeping: balancing the budget at levels which satisfy all reasonable requirements. In its simplest terms, it can be represented by an equation, or balance sheet, of gains and losses, and this in turn involves the measurement and evaluation of the main components.
Gains Losses Environmental balance
Rainfall and Evapotranspiration River runoff inflow Abstraction Spring flow Change in storage
Figure 1 shows the relationship between these components as elements of the water cycle. The processes involved in the planning and management of Kent’s water resources are based on boundaries which, in many instances, correspond to the watersheds separating the major river catchments (Figure 2). Elsewhere they are defined as sub-divisions of important aquifers such as the Chalk and Lower Greensand. Kent also receives flow from those parts of the headwaters of the Rivers Medway and Rother lying within Sussex (Figure 2) and this, together with its constituent groundwater, has to be included in the total resource to be set against the annual quantities abstracted for public supply, industry and agriculture.
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A Water Resource Strategy for Kent>> Reproduced with permission of the Environment Agency
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A Water Resource Strategy for Kent>> 2.2 Rainfall
2.2.1 Figure 3 shows the variations in average annual rainfall across Kent, calculated on the basis of the Meteorological Office long-term standard average for the period 1961-90. The overall average for the area is estimated at approximately 750mm, with the highest totals — exceeding 800mm — in the west and south. The north-east, by contrast, receives less than 600mm and ranks as one of the driest regions of the British Isles. After taking into account the large quantities lost by evaporation and floods we are left, for most years, with about a quarter of the original rainfall to meet the county’s water supply needs. With a population of nearly two million for the area defined in Figure 2, which includes Medway, part of East Sussex and part of London, this works out at an average “water availability” per head about the same as the Gulf state of Oman or half of Rwanda, and less than one third of Sudan’s ration. If climate change forecasts are correct, we must expect even less in years to come. Water is no longer a resource that can be taken for granted.
2.2.2 There is relatively little seasonal variation, the winter (October-March) and summer (April-September) periods recording 54% and 46% respectively of the annual total. November is generally the wettest month and December the driest. The vulnerability of Kent’s resources has been highlighted by recent drought experience, characterised by significant shortfalls in both winter and summer rainfall. Most of the episodes since 1989 have been marked by severely depleted river flows and an almost unprecedented decline in water table levels. It is in fact becoming apparent that even under average rainfall conditions the extent of development for public supply has brought a progressive deterioration in the regime of many important spring-fed streams and wetland habitats.
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A Water Resource Strategy for Kent>> 2.3 Evapotranspiration
This is the process whereby water is lost as vapour to the atmosphere from open water surfaces and as transpiration from vegetation. A small but important proportion is also lost during the summer months from areas of bare soil and wherever the water table is at a relatively shallow depth. The average annual potential loss rate for Kent (assuming constant availability of water) is estimated at between 500 and 550mm, nearly 80% of this during the spring and summer months (April-September). Actual annual losses for any given location will of course vary with water availability, but for most years the average would be around 400mm.
2.4 River flow 2.4.1 Each river system displays a pattern of seasonal flow variations which reflects the geological, topographic and land-use characteristics of its catchment area. For some catchments, the regime is strongly influenced by abstraction and river regulation. The range of variations is illustrated by Figure 5, which shows average annual hydrographs and flow duration characteristics for the Stour, Rother, Medway, Beult and Darent. The Stour is a predominately spring-fed stream with a high degree of natural regulation reflected in the relatively small winter/summer flow ratio. By contrast, the Beult, a clay catchment, has very little natural storage, and the high winter/summer ratio reflects the very “flashy” run-off characteristic. The Medway lies between these two extremes. It has a mixed catchment geology, including the clays of the Beult, but the large quantities of water abstracted during the winter for storage in Bewl Water and Bough Beech reservoirs (Figure 2) amount to a significant degree of artificial regulation. The system is therefore less flashy than would otherwise be the case for the catchment in its natural state. It is, reputedly, one of the most heavily regulated rivers for its size in England. This is due in large part to the impact of the Medway Scheme, a strategic pumped-storage and river-transfer facility based on Bewl Water Reservoir (Ref 3).
2.4.2 Kent’s landscape and river systems are products of a fairly equable climate, one which has also strongly influenced land use and agricultural practices. If climate change brings more extreme conditions, we will need to rethink the way in which we use the land and manage our rivers — this will mean formulating a single strategy which tackles both floods and droughts. In practice, it entails restoring some of the essential natural characteristics of the catchment which, prior to human intervention, would have regulated the response of the river to any abnormal fluctuations in yearly or seasonal rainfall. Rivers with a history of frequent “flash” flooding can be improved by changing the way in which land in the headwaters is managed, establishing mixed woodland and reinstating hedgerows and buffer strips. The result is a more even distribution of flows throughout the year, with reduced flood peaks and higher summer levels in reaches that might otherwise cease to flow or even dry out altogether. As a bonus, we also frequently see a corresponding reduction in soil erosion and channel siltation.
13 A Water Resource Strategy for Kent>> Fig 4 River flow measurement stations
Gravesend LONDON Sheerness Crayford Dartford
y HAWLEYra Margate C r
e Whitstable
v
i R
R i
Gillingham v e The Swale r River Darent River Medway W an Orpington ts Ramsgate Chatham um Sittingbourne West River Stour DARENT Faversham ur Malling to S NORTH Canterbury r River Len e iv Maidstone KENT R Sevenoaks Loose Stream Deal River Bourne HORTON Bough Beech Tonbridge TESTON Reservoir KENT River G KENTISH reat Stour reat Stour STOUR River Medway STILE BRIDGE River Eden River G River DourDover SURREY MEDWAY River Beult Ashford East Grinstead Royal River East Stour Weir Wood River Teise Reservoir Tunbridge Wells anal Bewl Tenterden ry C lita Folkestone Water Mi yal WEST Ro SUSSEX Crowborough EAST UDIAM ther SUSSEX udwell Ro Rive r EASTERN River D ROTHER Powdermill Key Darwell Reservoir Rye Lydd Reservoir Reproduced with the River Brede Flow measurement stations permission of the Environment Agency Hastings
Fig 5 Seasonal flow variations
Q is shorthand for flow
Q5 = Flow that is exceeded 5% of the time
inter
Q5
inter/
Q95 Q50
Q50 = Flow that is exceeded 50% of the time W
Annual
W
Average
Summer
Average
Average
as % rainfall % as Summer ratio Summer
Q95 = Flow that is exceeded 95% of the time Annual Average
Ml/d 100 100 80
60 1.9 143 40 2 54 14 40
20
Darent at Hawley at Darent 0 0 J F M A M J J A S O N D
Ml/d 2500 1500
2000 eston
1500 2.9 3485 402 129 940 40 1000
500
Medway at T at Medway 0 0 J F M A M J J A S O N D
Ml/d 500 300 400
300 4.7 847 38 6 173 33 200
100
Beult at Stile Bridge Stile at Beult 0 0 J F M A M J J A S O N D
Ml/d 500 300 400
300
200 3.2 838 71 15 198 44
100
Rother at Udiam at Rother 0 0 J F M A M J J A S O N D
Ml/d 500 350 400
300 1.9 707 193 86 268 38 200
100
Stour at Horton at Stour 0 0 J F M A M J J A S O N D
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A Water Resource Strategy for Kent>> 2.5 Groundwater
2.5.1 More than 200Mm³ — about 80% of Kent’s public water supply — is drawn each year from wells and boreholes tapping chalk and other water-bearing strata. This represents nearly half of the total average annual rainfall percolating through the soil to replenish our major aquifers, and of the remainder, the greater proportion becomes part of the general movement of groundwater emerging at distant points as springs or seepages. Most of this annual “recharge” accrues to the Chalk aquifer of the North Downs, the most important groundwater unit in Kent. The remainder is distributed between the Folkestone and Hythe Beds of the Lower Greensand, the Hasting Beds and the Lower London Tertiary deposits. In terms of their total thickness, the region’s water-bearing rocks underlying Kent make up about half of the total exposed geological succession shown in Figure 6. The Chalk, for example, has an average thickness of more than 200m, the Upper and Middle divisions of the sequence being the most permeable. Although intrinsically porous, the mass of the Chalk in fact contains relatively little available water, most of the flow being confined to the complex of inter-connecting fissures developed along fracture planes, many of these having been further enlarged by solution weathering. Storage capacity therefore varies widely depending on aquifer structure and post-depositional history, but for the most part the effective porosity or “storage coefficient” seldom exceeds 1 or 2%. This means that, on average, a cubic metre of chalk can be expected to yield between 10 and 20 litres of water. The capacity of the aquifer to convey water through its fissures is even more variable, the most freely transmissive regions often being associated with the larger fracture zones created by major earth movements. The alignment of these zones is generally evident at the surface from the course of the dry valleys which dissect the dip slope of the escarpment, and for many years now these features have been the preferred sites for the construction and development of public supply boreholes. The capacity of the fracture zones to transmit water is often several times greater than that of the intervening undisturbed chalk and their importance as water supply sources can therefore be appreciated.
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A Water Resource Strategy for Kent>> 2.5.2 In terms of the proportion of the resource committed for all water supply purposes, the Chalk of the North Downs must rank as one of the most intensively developed aquifers in the British Isles. The introduction to the Geological Survey memoir The Water Supply of Kent, 1908 (Ref 4) records that the county “contains the largest supply in the world that is got solely from wells”. The region is also one of the driest, with annual rainfall in the eastern extremity averaging less than 580 mm, and the aquifer has to support levels of pumped abstraction from boreholes approaching, and in some instances exceeding, the average rate of natural replenishment. The Chalk in Kent provides a resource for five water companies, together drawing 160 Mm³/annum, representing more than three quarters of the corresponding total supplied. And there are parts of east and south-east Kent which are entirely dependent on supplies drawn from boreholes in the Upper and Middle Chalk. The difficulties which have faced water companies in recent years have often been attributed to this heavy dependence on groundwater, a resource which is almost wholly reliant on winter rainfall for its annual replenishment. The region is therefore particularly vulnerable at times of below-average winter flow, and the experiences of the long drought of 1989-92 prompted the National Rivers Authority (NRA) to adopt a presumption against granting new licences for abstraction from the Chalk for all consumptive uses, including public supply.
2.5.3 More than 50% of an average year’s effective rainfall (the proportion of total rainfall accruing to groundwater storage) is re-abstracted for public supply and other uses. The disposition of the main urban centres (many of them along the coast or close to major rivers) is such that very little of the treated effluent finds its way back into the aquifer. Much of the drainage of the area is either wholly or largely supported by groundwater discharge in the form of spring flows or seepages, and the consequent depletion of natural storage has produced a corresponding decrease in the baseflow component of streams draining the outcrops of the Chalk and other major aquifers. In the most extreme cases, the result has been a total loss of flow over substantial lengths of the watercourse, and in many other instances groundwater abstraction has had a profound and detrimental effect on the seasonal pattern of surface flow.
2.6 Water use and demand 2.6.1 Control over abstraction falls to the EA under special provisions of the 1963 and 1991 Water Resources Acts. No one, for example, may abstract from any controlled water, (e.g. river, lake or aquifer) unless they hold a licence from the EA specifying the authorised purpose and quantities, or alternatively have explicit exemption (examples here being fire fighting and dewatering to protect works). The first licences were granted in mid 1965, but the conditions of issue allowed very little scope for the authority at that time to exercise effective control. The legislation entitled anyone who could demonstrate proper existing use of a borehole or other recognised source of supply to a licence “as of right” for the appropriate quantities — and in perpetuity. With few exceptions, this provision, almost by definition, had to be applied automatically to all public water supply undertakings (the largest abstractors), not to mention some fairly large industrial users. Effectively, this put much of the Chalk into deficit from the outset, and the subsequent 40 years of water resource management have been largely dedicated to attempts to redress this imbalance in the face of rising demand and increasing pressure on the water environment. Public water supply represents the greatest proportion taken from both surface (non tidal) and groundwater sources, and in an average year accounts for approximately 80% of the authorised total.
2.6.2 Table 1 compares current authorised and actual abstractions for the principal use
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A Water Resource Strategy for Kent>> categories, based on the returns for 2003, the most recent year for which figures are available. Figure 7 shows the proportions of actual abstraction represented by the main use categories. As it happens, the estimate of 1m³/head/day for effective rainfall corresponds fairly closely with the total quantity of water (about 600 million m³/yr) licensed by the EA for abstraction from rivers and boreholes for all authorised purposes (although actual abstraction in an average year runs out at about half this figure). The greatest proportion of abstracted water is taken for public supply by the six water companies operating in Kent (Figure 8) and the majority of this (75-80%) is drawn from wells and boreholes in the Chalk aquifer of the North Downs and other important water-bearing strata in the Weald (Figure 6). These sources have for centuries provided reliable supplies of high-quality water, but the last 100 years or so have seen a sharp increase in the total quantity pumped from groundwater, with severe consequences for the streams and wetland areas dependant on the springs which flow from these natural reservoirs. The high ratio of authorised to actual abstraction in Table 1 has its origin in the “Licences of Right” granted to existing abstractors in the mid 1960s, but is now being addressed by the EA under the Catchment Abstraction Management Strategy (see 3.8).
Table 1: Water Abstraction In Kent 2003 Purpose Source Authorised Actual Mm3/yr Mm3/yr
Public supply Surface 138.7 38.8 Groundwater 274.3 167.5 Total 413.0 206.3
Transfer Surface 47.2 12.0 (public Groundwater 0.7 0.1 supply) Total 47.9 12.1
Industrial Surface 63.7 13.1 Groundwater 54.8 39.7 Total 118.5 52.8
Irrigation Surface 8.0 2.2 Groundwater 2.0 0.8 Total 10.0 3.0
Agriculture Surface 0.3 0 Groundwater 0.8 0.2 Total 1.0 0.2
Fish culture Surface 14.8 1.8 Groundwater 1.3 0 Total 16.1 1.8
Total Surface 272.7 67.9 Total Groundwater 333.9 208.3 Grand total 606.6 276.1
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2.6.3 Public water supply The six water companies operating in the Kent area serve a total consumer population of approximately two million, with a corresponding aggregate demand (including distribution losses) averaging 690 Ml/d. Table 2 provides a summary of authorised abstractions and actual (deployable) outputs for individual companies. Bough Beech reservoir also supplies water to Surrey and south London.
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Table 2: Daily public water supply in Kent area – Ml/d
Authorised abstraction Deployable output Water company Surface Groundwater Surface Groundwater
Southern Water Services (SWS) 139.1 265.1 81.4 190.5
South East Water (SEW) 3.9 68.3 2.9 55.4
Mid Kent Water Co (MK) 25.8 214.7 20.5 168.4
Folkestone & Dover Water Co (FDWS) 0 88.2 0 49.9
Thames Water Utilities Ltd (TWUL) 0 178.6 0 153.9
Sutton & East Surrey Water Co (SESW) 27.2 16.2 27.4 15.5
Total 196.0 831.1 132.2 633.6
One megalitre (million litres) per day = 365,000 cubic metres (m3, or thousand litres) per year, or 0.365Mm3/yr. The surface water component is mainly supplied via impounding or pumped storage reservoirs, notably Bewl Water near Tunbridge Wells (fed from the River Medway), and Bough Beech Reservoir (which draws from the River Eden, in the upper reaches of the Medway catchment).
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Table 3: Reservoirs in Kent area
Reservoir Area Volume Yield Catchment Operating company (hectares) (Ml) (Ml/d)
Darwell 73 4,728 21.9 Rother Southern Water Services
Powdermill 21 856 2.1 Rother Southern Water Services
Bewl Water 312 31,300 75 Medway Mid Kent/Southern Water
Bough Beech* 130 10,100 27 Medway Sutton & East Surrey Water
Weir Wood 113 5,623 14 Medway Southern Water Services
* Bough Beech reservoir also supplies water to Surrey and south London.
2.6.4 Industrial Approximately 20% of the total quantity licensed for abstraction from groundwater and non- saline surface water is designated for industrial purposes, but less than half of this is used in any given year. Most of the abstraction is concentrated in the north-west of the area and associated with power generation and the major manufacturing industries, notably cement and paper. A distinction can be made here between the latter group, with its generally high net consumptive use, and categories such as power generation and mineral extraction, which are low net users and return a relatively high proportion to source. Overall, the record shows a general and progressive reduction in direct abstraction for industry due, partly, to the shut down of the traditional high-use processes and the adoption of more water-efficient technology. Returns of water abstracted during 2003, for example, show a total usage of 145Ml/d from surface and groundwater sources, compared with approximately 400Ml/d in 1963 (a reduction of more than 60% over the 40-year period).
2.6.5 Irrigation Spray irrigation is still mainly confined to the cultivation of high-value crops, with a current authorised total of approximately 10,000Ml/annum. This represents an increase of around 50% over the last 30 years, but there has also been significant growth in the use of trickle irrigation which, until the 2003 Act, was not subject to licensing control. On the basis of the latest estimates, usage in this category probably accounts for a further 1,500Ml/annum.
2.7 Balancing the books 2.7.1 The water balance estimates summarised in Figure 9 are based on data relating to the long drought of 1989-92, this being a recent example of an event approximating to the notional “design drought” used in the assessment of water supply and water resource management schemes. (Water companies, as statutory undertakings, must comply with prescribed levels of service, including the maintenance of supplies under drought conditions
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A Water Resource Strategy for Kent>> of a severity normally exceeded on average only once every 10 years.) The estimates reveal the sharp regional distinction between the apparently healthy balances for the areas in the south and west and the heavily committed, mainly groundwater dominated areas of the north and east. It is the latter group which generally receives special attention in the discussion of issues, but even in the relatively low-stress areas there are instances of localised environmental impact which will have to be addressed at some stage.
2.7.2 For most of the resource areas which can be described as groundwater dominated, the assessment shows that even in a year of average rainfall the authorised abstraction accounts for more than 70% of the effective rainfall. For 1989-92, the commitment increases to 80% with some areas (notably north Kent, Thanet and Darent) exceeding 100%. To this extent, therefore, it has to be recognised that important regions of the Kent area are already subject to an environmental deficit, and this is reflected in the many examples of severely depleted spring-fed streams and designated wetlands. The most conspicuous examples include the streams draining the outcrops of the major aquifers, three of which (Darent, Little Stour and Dour) feature in the national low-flow alleviation programme. Figure 10 allows a comparison of the resource balances under average year and drought year conditions, the “design drought” again being represented by the 1989-92 event, which produced an average annual rainfall approx 86% of the standard (1961-90) long-term average (LTA). The average year is based on the data for 2003 which, for most of Kent, recorded a rainfall total approximately 5% above LTA. It can be seen that the fairly small reduction in rainfall of 13 to 14% produces a relatively large reduction of approximately 40% in the available resource.
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2.8 Some lessons from the long drought 2.8.1 With more than three quarters of Kent’s public supply dependent on groundwater (most of this drawn from the Chalk of the North Downs) any material changes in the balance of aquifer resources are bound to have a profound impact on water conservation and supply strategies throughout the county. The droughts of recent years have been marked by some notably dry winter and spring periods, and the consequent shortfall in aquifer recharge has highlighted the vulnerability of those water undertakings which are either wholly or largely groundwater based.
2.8.2 If the increasing frequency of drought events can be taken as part of the process of climate change in south-east England, then it should be possible to apply the lessons learned to good effect in the long-term management of water resources. The long drought of October 1988 to September 1992 produced, in east Kent, a cumulative deficit of 600mm, equivalent to an average year’s rainfall. Corresponding rates of groundwater recharge were estimated at little more than 50% of average, and historic minimum water table levels were recorded throughout the unconfined aquifer. Total annual runoff for the major spring-fed streams fell to less than 40% of average, while smaller watercourses suffered an almost total loss of summer baseflow. Post-drought recovery was slow and erratic, with large areas achieving only 30% of the normal recovery range by mid-winter 1994. Many of the conditions experienced during 1989-92 were revisited in the summer and autumn of 1995. And the severe winter drought of 1995-96, which produced less than half the normal rainfall,
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A Water Resource Strategy for Kent>> continued to have its effect, with groundwater storage and baseflows again reaching record minimum levels.
2.8.3 Taken in the context of long-term climate change, the droughts of the late 1980s-to- mid-1990s have to be seen as part of a progressive deterioration in the balance of water resources in the South East. The rainfall records for the Stour Valley show a decrease in annual totals of between 10% and 20% over the last 100 years. There would seem to be a corresponding long-term depletion in groundwater storage which is considerably steeper than can be accounted for by the recorded increases in borehole abstraction. Changes in Chalk stream flow duration profiles over the last 30 years further confirm the downward trend, with normal minimum summer baseflow (95 percentile) for the Little Stour and Dour falling by 45% and 63% respectively since the mid 1970s. If we take the flows below the median (50 percentile) as broadly representative of the summer and autumn condition, the record shows a general decrease in seasonal low flows by up to 50% in less than 30 years (see Appendix I).
2.8.4 There are clear implications here for the long-term management of groundwater resources, in so far as there is no remaining scope for exploiting aquifer storage without lasting detriment to river and associated wetland environments. In extreme cases we face the prospect of mining groundwater, in the sense that further general increases in borehole abstraction would almost certainly preclude full recovery of storage except in years of above- average winter rainfall. This must therefore effectively increase the critical period of any given aquifer system, with consequent loss of operational flexibility and an almost inevitable fall in drought output capacity for many public supply sources.
2.8.5 A groundwater resource can only be managed effectively on the basis of long-term minimum reliable recharge, and current levels of abstraction will not therefore be sustainable if the drought events of recent years are in any way indicative of the conditions likely to obtain as a future consequence of climate change. Notwithstanding all this, a view persists in some water supply circles that exploitation of groundwater storage is a practicable resource management option. Its supporters further assert that those water companies which are wholly dependent on borehole supplies are likely to cope better under drought conditions than those reliant on the yield from reservoirs filled from “short” rivers. Kent’s experience, however, suggests otherwise, as for the most part the companies which have come through the drought years with least difficulty are those operating very flexible supply networks which draw on a mix of sources.
2.8.6 Another popular myth is that adequate reserves of groundwater remain for further development and that there is “plenty to be had” by those companies prepared to sink deeper boreholes. This evidently pre-supposes broadly uniform aquifer characteristics irrespective of depth, which is manifestly untrue. Most significantly, though, it disregards the evidence for progressive storage depletion and the impact that such a supply strategy, even if successful in the short term, would have on our spring-fed streams and the river environment in general. Unhappily, the process of groundwater and baseflow depletion is self evident, and it was primarily for this reason that the NRA was obliged to implement a nationwide low-flow alleviation programme covering 40 of the most seriously affected streams in England and Wales. The view also once persisted that groundwater was able to recover quickly without problems, but the recent experience of hosepipe bans, supply restrictions, loss of river flows, fish deaths and habitat destruction has exposed this fallacy. It is even questionable as to whether the Chalk of east Kent is now ever likely to show full recovery, bearing in mind the evidence of a general and progressive depletion in storage.
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A Water Resource Strategy for Kent>> 3 Managing Water in Kent: The story so far
3.1 Beginnings 3.1.1 The Geological Survey memoir The Water Supply of Kent, 1908 (Ref 4) includes a quote from a Royal Commission report on current rates of abstraction from the Chalk of north-west Kent. It reads: “When the amount pumped for 1903 by the Kent Water Company is added to that of the manufacturers, the total amount of water pumped within the area of the [KWC] is not less than 40,000,000 gals/day [approximately 182 Ml/d]. This is far in excess of the average limit of 27,500,000 as stated by Lord Balfour’s Commission”. The conclusion is then drawn that “if this rate continues, the quantity taken must be far and away above what can be restored to underground supplies from the rainfall, so that… we shall have to face a check in our industrial development as well as a curtailment in the amount of water that can be drawn from these areas”. The challenges of water resource management in the South East are clearly not new, and certainly not confined to recent drought experience. Kent’s aquifers have for many years provided the greater proportion of supplies developed for public and industrial use.
3.1.2 By the time of the first annual report of the Metropolitan Water Board in 1904, the north-west Kent Chalk well field was already supplying south-east London with 80Ml/d, and this was additional to the average daily abstraction, estimated at that time to be in excess of 100Ml/d by the 80 or so local industries drawing supplies from their own wells. Trends in combined public and industrial usage from around 1900 to the present day indicate a three- fold growth in demand for much of north Kent. The Medway towns, in fact, seem to have experienced appreciably higher rates of growth for the same period, with demand increasing tenfold. This is typical of areas of urban development associated with industrial and commercial expansion in north-west Kent during the first half of the 20th century, when very little formal control was exercised over abstraction from rivers or aquifers. 3.2 Controlling abstractions – the 1963 Water Resources Act 3.2.1 Recognition of the need for more balanced development of resources came with the 1963 Water Resources Act, which imposed on the newly formed river authorities a duty to secure the proper use of water resources. Provision was made for the control of abstraction by the issue of licences specifying annual and daily maximum authorised quantities, and these were applied retrospectively to existing users, who were designated as licence holders “as of right”. Under the regulations in force at that time, the river authority was more or less obliged to grant licences on the basis of the installed abstraction capacity, rather than any consideration of actual need for the required quantities or the likely impact on the resource. Subsequent applicants were subject to more stringent restrictions, with the licences carrying special conditions applied in order to protect existing lawful interests and, it was hoped, arrest further depletion of both surface and groundwater resources. Most importantly, abstraction under these “ordinary” licences could, for the first time, be controlled by reference to Minimum Residual Flows (or levels) prescribed for any water course likely to be adversely affected. They are essentially “hands off ” conditions, and they have proved to be amongst the
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A Water Resource Strategy for Kent>> most effective instruments available to the regulating authorities in their efforts to redress the resource imbalance.
3.2.2 By and large, taken together with the amendments and additions provided by the 1991 Water Act and 1995 Environment Act, the Water Resources Act has served well enough. But the severe droughts of the late 1980s and early-to-mid 1990s exposed its limitations as an instrument for maintaining an effective balance of catchment resources in the face of increasing demand for public supplies and the correspondingly greater pressures on the water environment in Kent, where abstraction was beginning to outstrip the rate of natural replenishment, with severe consequences for many rivers and wetland areas. The overriding obligation to have special regard to public supply requirements meant that efforts exerted in environmental protection were more in the spirit of minimising than preventing any adverse impact of new source developments. 3.3 Water for Life – the CPRE national strategy 1993 3.3.1 The shared experience of the droughts of the late 1980s and early-to-mid 1990s brought a realisation, throughout the South East, that water was no longer a resource that could be taken for granted, and that a new approach was needed if further development and management of public supplies was to be achieved without detriment to the wider environment. This shift in perception was reflected in the Department of the Environment’s 1992 publication Using Water Wisely (Ref 5) and in the CPRE national strategy document Water for Life, published in the following year (Ref 6). In the latter it was advocated that full use should be made of existing water resources before resorting to new sources of supply. In 1991 we had campaigned for the introduction of selective metering, better leakage control and widespread education in water conservation. There was also seen to be a case for financial incentives as key elements of a future environmental “tool kit” which would have special application to the planned growth areas in Ashford and Thames Gateway. The social and environmental implications of the traditional approach of “building our way out of water shortages” pointed to the need for a new water policy.
3.3.2 Conclusions i] For the most part, water company strategies for meeting demand growth still show an emphasis on development of new resources to enhance supply-side capacity ii] Water efficiency and conservation options are still seen as secondary iii] Only 10-15% of all water supplied is used for purposes which require the statutory standards of purity demanded under the EC Directive on Water Quality iv] There is no single development strategy which, although satisfying the basic criteria of sustainability, will represent the best option for all social and economic imperatives. These change both geographically and with time, and also vary with the mix of domestic, commercial, industrial and agricultural use v] The Southern, Anglian and Thames regions need to review their management policies in anticipation of the changing needs of the 21st century vi] Current source development often goes ahead without first considering the scope for making more effective use of existing capacity. The result of this is a more costly strategy for public water supply consumers and the wider community than would otherwise be the case
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A Water Resource Strategy for Kent>> 3.3.3 Recommendations
i]Policies for the management of water resources must address the requirements of environmental, social and economic sustainability ii] It is essential to evaluate the full range of strategic options, as the best outcome may be a mix — albeit with less emphasis on the development of new sources of supply and more attention given to water-efficiency measures iii] The range of options is wide and may cover all of the following categories:- ● Collective action ● Direct regulation ● Education and raising awareness ● Economic incentives iv] The industry regulators need to adopt a more proactive demand management strategy v] The water companies and Ofwat should have a statutory duty to promote the efficient use of water and the companies should have an economic incentive to invest in conservation rather than new capacity vi] All local authorities should address water resource issues in forward planning and development control vii] The cost-recovery restrictions on the NRA [EA] should be replaced by an incentive-based formula which relates the charge to the resource and/or environmental impact viii] Legislation should make provision for “water trading,” including substitution of reusable wastewater (grey water) for new potable supplies. This would apply, for example, to irrigation or other non-potable uses ix] There should be further investigation of the potential for direct or indirect re-use of wastewater and recycling of domestic grey water. (It should be noted that, with the increasingly stringent environmental quality targets, it is becoming as expensive to treat for disposal as for potable supply. It therefore makes economic sense to re-use rather than develop new sources of supply) x] There should be no further development of new sources of supply until all practicable measures have been taken to effect maximum uptake of domestic metering of properties within the relevant supply areas. There should also be an appropriate charging tariff to encourage good water-efficiency and conservation practices xi] Further effort should be made by the water undertakings to achieve maximum practicable reduction in distribution leakage.
3.3.4 The underlying principles still hold true today in the formulation of a sustainable management strategy. If anything, there is a greater awareness of the implications of demand growth in the South East and the impact of global warming as major factors influencing the balance of resources. In spite of this, very little progress has been made toward their incorporation in water company strategies and business plans. This is notwithstanding the provision, under the Environment Act of 1995, that makes it the duty of every water undertaker to promote the effective use of water. This act also saw the establishment of the Environment Agency, with the duties, inherited from the NRA, of: ❏ Conserving, redistributing or otherwise augmenting water resources, and ❏ Securing the proper use of water resources in England and Wales.
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A Water Resource Strategy for Kent>> 3.4 A national resource
Options for the sustainable management of water resources were set out by the NRA in 1994 (Ref 7) and in the National and Regional Strategies published by the EA in 2001 (Ref 1). These are now in process of being updated (Ref 11) with an emphasis on the management of demand, control of leakage and promotion of good conservation practices — prerequisites for any new resource development schemes. This still leaves scope for strategic transfers and bulk supply arrangements between companies, which should be given attention ahead of development of additional reservoir capacity. Above all, the strategy recognises that unless pursued as part of a closely controlled recharge and re-use programme, there is no future for further general development of groundwater for consumptive use in Kent. If the most recent climate change forecasts prove to be substantially correct, many water undertakings will be obliged to reduce dependence on borehole sources in order to maintain peak-demand capacity. 3.5 Directing the Flow — a policy for England 3.5.1 The UK Government, recognising the seriousness of the water supply problem, set out its priorities for future water policy in England in the Defra (Department for Environment, Food and Rural Affairs) document Directing the Flow, November 2002 (Ref 7). This put an emphasis on the need for prudent use of water resources “within the limits of replenishment”. This precept was reflected in a number of important conclusions and recommendations relating to the future management of resources and water supplies, at that time under review in the finalisation of what was to become the Water Act 2003. 3.5.2 Conclusions ❏ On present trends, it is far from clear whether there will be sufficient water resources to meet demand growth beyond 2025. Abstractions from both surface and groundwater are already at, or close to, their limits. For Kent, both winter and summer abstraction regimes are classified as unsustainable or unacceptable ❏ The stress on the South East is likely to increase further with climate change and planned housing growth ❏ Further stress on resources may arise from the increase in demand for irrigation, fisheries and fish farming. Land-use changes can also affect the natural run off from river catchments, accelerating erosion rates and channel sedimentation ❏ New obligations arising from the European Water Framework Directive will require the setting of more stringent control-flow conditions in order to satisfy the criteria for good ecological and water-quality status ❏ Resources will also need to be reserved or enhanced to improve biodiversity and upgrade the recreational value of our inland waters
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A Water Resource Strategy for Kent>> 3.5.3 Recommendations
On planning: ❏ Water companies will be required to provide Water Resource Management Plans with a 2020 horizon. Drought plans will also become statutory requirements ❏ Water company plans should also include estimates of long-run marginal costs which take full account of environmental and quality enhancements ❏ The British Waterways network should be developed to provide a range of supply and management services. On regulation: ❏ Water Act 2003 will amend the abstraction licensing system to provide for time limiting of all new water abstraction licences and other measures to improve the balance between environmental and economic considerations ❏ The EA will continue to coordinate the production of the Catchment Abstraction Management Strategies (CAMS) ❏ The water companies will also have a duty to use water efficiently in carrying out their functions ❏ There will be provision in the act to encourage more competition between undertakings in the supply of water to large non-domestic customers, and a basis for water pricing that will balance consideration for water resources and the environment against the social, economic and health implications of charges. On water efficiency: ❏ The expansion of domestic metering should be permitted on a voluntary basis ❏ Water company targets should reflect improved efficiency of supply and leakage reduction ❏ There should be a review of the scope for incentives to maximise the efficiency of agricultural water use (principally irrigation) ❏ There should be continuing research to refine the assessment of the impact of climate change on water demand. 3.6 The Water Act 2003 This marks a major advance in the control of abstraction, with specific provision for time- limited licences or their revocation by the EA, without compensation, on grounds of environmental protection. The agency can also, under certain conditions, cancel a water company’s licence and reallocate to another undertaking or, in other circumstances, require them to seek a bulk supply from a neighbouring company. The water companies also have new duties with respect to conservation and demand management initiatives, and the publication, each year, of Water Resource Management Plans. 3.7 The European Water Framework Directive 3.7.1 Many of the key provisions of the 2003 Act have been put in place to facilitate compliance with the European Water Framework Directive of 2000 (Ref 2), which now sets the parameters for national water-management policies. It requires all member states to take measures for the protection, improvement and sustainable use of Europe’s rivers, lakes, estuaries, coastal waters and ground waters. These measures are to be implemented as elements of River Basin Management Plans (RBMPs), formulated in accordance with specific
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A Water Resource Strategy for Kent>> environmental objectives and reviewed on a six-year cycle. For water resources, these have been summarised as: ❏ No further deterioration in status ❏ Restoration to good status ❏ Compliance with the water quality objectives for protected areas. 3.7.2 The timetable for implementation includes the following key stages:
2006 Publish and consult on a timetable and work programmes for the production of RBMPs 2007 Publish and consult on an interim overview of significant water management issues for each River Basin District 2008 Publish and consult on drafts of RBMPs for delivery of environmental objectives 2009 Publish first RBMP for each district (including environmental objectives) 2010 Ensure proper water pricing policies are in place 2012 Operational programmes for delivery of environmental objectives. Follow with interim progress reports 2015 Main environmental objectives to be met. Thereafter, review plans at six-year intervals. 3.8 Catchment Abstraction Management Strategies 3.8.1 The principal objectives of the RBMPs were anticipated by the EA in the formulation of the Catchment Abstraction Management Strategies (CAMS) (Ref 9) and some of the concerns raised by CPRE in Water for Life are now being addressed in the constituent Water Resource Assessments (water “audits”) and sustainability appraisals. The aim of these is to establish a more balanced regime of abstraction and environmental needs for each major river catchment (“Water Resource Management Unit”) or aquifer (“Ground Water Management Unit”). Taking each unit in turn, the balance of resources determined in the initial assessment stage is then compared with whatever might reasonably be regarded as the minimum requirements for a satisfactory environmental status. A conclusion is then reached as to whether the unit in question is in surplus or deficit in terms of both actual or licensed abstraction (Figure 11). The sustainability appraisal stage which follows is essentially a qualitative process by which a unit is “scored” under the four headings of environment, economics, society and resource use.
3.8.2 For some Kent catchments, the CAMS process has already identified major public supply sources that will either need to be closed down or substantially reduced in output by the due date of 2015. This should add impetus to the formulation of more sustainable resource development plans and water company business plans leading to a more equitable balance between supply-side and water-efficiency components. An “appropriate assessment” is also required under the Habitats Directive (Ref 10) in order to satisfy the competent authority (English Nature) that current levels of abstraction allow adequate flow of fresh water into or within any designated “high priority” sites. To this end, English Nature can invoke the precautionary principle.
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A Water Resource Strategy for Kent>>
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A Water Resource Strategy for Kent>> 4 Kent’s future needs – where do we go from here? 4.1 It has proved increasingly difficult to maintain supplies in Kent under drought conditions, but the management strategies discussed earlier have enabled a balance of sorts to be struck. Now, however, the county is facing serious long-term supply problems arising from the combined impact of climate change, housing growth and the new commitments under the European Water Framework and Habitats Directives. There is evidence to indicate a progressive depletion of storage throughout large areas of the Chalk of north and east Kent. The condition has its origins in the steep post-war increase in demand, coupled with what appears to be a fairly consistent decrease in average annual rainfall taking place since the early years of this century. Conditions have of course been exacerbated by recent droughts. Even allowing for this, though, the trend in groundwater levels for some parts of the area suggests that we are now in danger of mining aquifer resources, insofar as rates of abstraction exceed the average annual winter recharge for the more severe and protracted droughts. And it can require two or three years of above-average recharge to bring about full recovery of storage. It would seem that in order to achieve sustainable management of the aquifers’ resources, it will be necessary to make changes in the geographic and seasonal distribution of groundwater abstraction. This in turn requires some revision of the criteria for assessing the long-term balance of resources. As a consequence of this, we will need to work toward a general reduction in the level of dependence on groundwater and to suspend the granting of new consumptive-use licences until the annual abstraction totals can be brought back to rates that can be sustained without detriment to the environment.
4.2 Demand in Kent has now reached a level where the county stands almost alone in having a virtual year-round deficit in the balance of river and groundwater resources. In recognition of this, it has been classified by the EA as having an unsustainable regime for water abstraction under both summer and winter conditions (Figure 12). We have, as a consequence, reached a state where the available water, per head of population, is now said to be less than many regions of southern Europe and the Middle East. The problems of supply and distribution are further exacerbated by the absence of a coherent water resource management strategy which is both environmentally sustainable and able to ensure adequate levels of service under all but the most extreme drought conditions. Each of the six separate and independent undertakings involved in the supply of potable water to consumers in Kent (more than any other county or area of comparable size) has its own set of business plans and investment programmes, and the regime is therefore not one which can be relied on to ensure long-term consistency in the pursuit of key water management or public supply objectives. Furthermore, those schemes which eventually evolve from this process do not have the makings of a sustainable strategy for Kent as a whole.
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A Water Resource Strategy for Kent>>
4.3 The companies can of course point to the work of the South East Water Resources Forum, established under the aegis of the South East England Development Agency (SEEDA) and the EA. This has certainly provided a useful meeting point for discussions covering a wide range of resource management issues, but it does not have a remit to formulate an optimum strategy or to direct water companies in its implementation. There is no such body. Examples can of course be found of joint schemes promoted by the companies, but these are primarily business driven. While they must comply with Ofwat’s customer charging limits and also satisfy the EA criteria relating to need, sustainability and environmental impact, they do not, even taken together, constitute a strategy which measures up to the demands that we already face and which will inevitably increase.
4.4 Most water company strategies still have an emphasis on the further development of river and groundwater resources, with relatively little attention, as yet, directed to water-efficiency or re-use initiatives. Environmental impact is still very much a secondary consideration. This comes at a time when Kent faces unprecedented population growth and the prospect of continuing acceleration in the rate of climate change, with consequent further stress on an already fragile balance of resources. Just how fragile has been demonstrated by the heavy
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A Water Resource Strategy for Kent>> losses in groundwater and reservoir storage sustained as a result of the severe shortfall in rainfall during the autumn/winter period of 2005/06, the deficit exceeding anything previously recorded for this time of year.
4.5 A number of key issues were highlighted in the 2004 Review of the EA’s National Water Resource Strategy (Ref 11). It acknowledged that some progress had been achieved in household metering and control over the growth in per-capita consumption, but there remained areas of special concern, notably:
❏ Further reductions in distribution leakage needed over the next 20 years ❏ Water company resource plans are still too heavily biased toward new source developments such as river abstraction/reservoir schemes ❏ Insufficient progress is being made on domestic demand management ❏ Additional housing in the South East will put more pressure on water resources in the driest parts of England ❏ Climate change continues to present a threat, both to abstractors and the environment.
4.6 The case would therefore seem to have been made for a management strategy which addresses the three major influences on the balance of resources in Kent, namely: ❏ The planned housing growth for the South East, with the consequent increase in public supply demand — we should here include any concurrent growth in agricultural and industrial use ❏ The ongoing impact of climate change, increasing demand while at the same time reducing rates of natural replenishment ❏ The need for water companies to make good any losses in source output resulting from new and more demanding environmental targets imposed under the EWFD and Habitats Directive.
4.7 We have assumed, for purposes of a first estimate, that any potential for growth in per capita consumption, not counting any climate change factors, will be offset by demand management initiatives, given that these continue at the current relatively low level. This is a more optimistic scenario than that envisaged in 2002 by Defra, which saw household consumption continuing to outstrip growth in household numbers. Separate estimates of growth in industrial and agricultural use are also required in order to refine the overall out- turn demand for the South East Plan period (2006-2026). Some allowance will also need to be made for the increase in exports from Bewl Water to the Hastings supply area, for which Southern Water have a licence for the transfer of up to 35Ml/d via Darwell reservoir. As yet, no transfers have been made under this licence, and any future use would therefore have to be treated as additional to the forecast demand growth.
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A Water Resource Strategy for Kent>> 4.8 Housing growth – the South East Plan in Kent The plan provides for the construction of 122,000 dwellings throughout Kent and Medway during the period 2006-2026 (Ref 12). This will consist of:
Kent Thames Gateway 48,000 Ashford 30,000 Other east Kent 18,000 Rest of Kent 24,000 London fringe (Sevenoaks) 2,000 Total 122,000
Assuming an average occupancy of two, and consumption of 160 litres per head per day (l/h/d), this would represent a demand increase for the plan period of 39Ml/d (average day). Allowing 25% for peak-week demand and supply headroom would give a corresponding “dry year” critical period demand increase of 49Ml/d. As will be seen from the discussion in 5.1, this commitment alone exceeds the current dry year supply/demand surplus (40 Ml/d) for Kent.
4.9 Industry and agriculture There are few reliable indicators of likely future trends in industrial abstraction, but it would seem reasonable to assume that rising costs will drive further efficiency savings by the major water users and that these will offset any underlying demand growth. Agricultural use, on the other hand, looks set to increase, with the forecast impact of climate change on irrigation demand for horticulture and market-garden field crops. One likely scenario envisages fairly strong growth (CAP notwithstanding) with supermarket quality targets driving increased irrigation demand for higher value produce. Estimates for 2026, even assuming relatively modest climate change trends, indicate an average increase for the UK at least 20% above current levels, and the equivalent for the South East would be expected to exceed this. Adding the effect of the “most likely” socio- economic scenario envisaged for the South East Plan, coupled with the anticipated growth in the home market, would increase this estimate when factored up for high value crops. Taking actual abstraction, as of 2000, at an annual average of 6Mm³/yr, and growth to 2026 at 50%, would add 3Mm³/yr by the end of the plan period. This is equivalent to a year-round average of 8Ml/d. No allowance has been made for growth in water demand in any other agricultural sector.
4.10 Climate change impact 4.10.1 Global warming now features as one of the most important single influences on future trends in catchment water balances and public supply demand. The most recent forecasts by UKCIP (UK Climate Impacts Programme) 2002 for south-east England give a picture of increasing average annual temperatures and a trend toward more extreme fluctuations in seasonal rainfall. This is popularly interpreted as “wetter winters and drier summers”. We must therefore expect to see an increasing frequency of severe and protracted summer droughts, with high soil moisture deficit levels persisting for longer periods. This latter factor in particular could negate any resource benefit likely to accrue from a higher winter rainfall, especially as some forecasts indicate that this could take the form of relatively short and intense storms producing high rates of flood runoff which would contribute relatively little to groundwater replenishment and offer few opportunities for diversion to storage. This scenario of an increasingly erratic climate must add to the uncertainties already inherent in
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A Water Resource Strategy for Kent>> the management of water resources (see Appendix I). If the future means more severe droughts, we will have to plan for greater peak season demands for public supply and irrigation. Extreme conditions are inevitably harder to manage — wet winters do not necessarily compensate for dry summers, and this could present new challenges in sustaining supplies and protecting the water environment.
4.10.2 There are certainly parts of the Stour Valley between Wye and Canterbury where daily rainfall records (some of which have been maintained for more than 100 years) show a marked decrease in the yearly average. At the same time, there are stations along the coast where the records show very little change, and in a few cases there are even signs of a slight increase. By contrast, the evidence for rising temperatures is more consistent, and this could, in the long run, prove to be the most important factor, bringing in its train higher evaporation and plant transpiration rates and driving up summer demand peaks. Just what these changes may mean for our water resources can perhaps be gauged from their effect, so far, on river flows. The baseflow of the Great Stour, for example, appears to have decreased by 25% over a period of 35 years, and only about one third of this loss can be accounted for by increases in water supply abstraction. Most of the changes that we see taking place almost certainly result from a combination of factors, including climate change and demand growth.
4.10.3 As to what this could mean for the future public supply/demand balance: findings from recent Defra studies reported in the EA 2004 review (Ref 11) suggest increases in demand, as a UK average, of around 2% by 2025. The corresponding effect for Kent would be more pronounced, and if we take 3% as a working estimate, this would be equivalent to an increase of 23Ml/d for the end of the plan period (approximately 0.5% per year). Recent model studies by UKCIP have shown that annual river flows could fall by the 2020s with “significant reductions in summer averages”. The EA has also forecast a decrease in the deployable output of public supply boreholes drawing on the North Downs Chalk aquifer (Ref 13).
4.11 The environmental dividend: EWFD, Habitats Directive and the CAMS process The CAMS process, if carried through as envisaged, will provide the impetus for a more sustainable resource management strategy, bringing with it the prospect of a progressive improvement in the environmental quality of Kent’s rivers, wetlands and aquifers. It requires, however, that certain water companies relinquish a proportion of their public supply capacity (most, if not all, drawn from groundwater), and the success of the strategy will rest on their ability to secure viable alternative sources. This is easier said than done, bearing in mind that Kent offers virtually no scope for further development of existing resources. Assessments have not yet been completed for all of the CAMS catchments in Kent, and a full picture of the implications for the water companies is not likely to be available before 2007/8. However, on the basis of the initial findings for the three completed studies (Stour, Medway and North Kent/Swale), it would seem that there will be a need for some substantial reductions in groundwater abstraction in the more heavily stressed management units. Taken together, the constituent water companies could be facing a total shortfall of at least 50Ml/d, with a replacement deadline not later than 2015. This is a substantial quantity, but represents less than 7% of the current total deployable output. No separate allowances have been made for compliance with the Habitats Directive, which cannot be quantified with any confidence at
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A Water Resource Strategy for Kent>> this stage (particularly as it allows the competent authority to apply the precautionary principle in the assessment of environmental impact and any subsequent setting of abstraction-control conditions).
4.12 Total forecast demand for Kent, 2026
Ml/d Dry year demand at 2006 ...... 725 Public supply growth (incl. headroom)...... 49 Climate change (3% of 2026 out-turn)...... 23 Agricultural irrigation ...... 8 Total ...... 805
Figure 13 shows the principal components of demand growth over the next 20 years. Until recently, public supply levels have been held more or less steady from the mid 1990s at around 725Ml/d, mainly by leakage control and a degree of demand management resulting from the voluntary domestic metering programme. The figure therefore represents the current “critical period” 1-in-10 dry-year demand (Ref 1). From 2006 onward, demand is assumed to grow in accordance with the South East Plan, and if we take the current regional assembly’s figures to be those presented in the KCC/Medway consultation document (Ref 12) this would provide for an additional 122,000 dwellings, constructed at an average rate of 6,100 per year between 2006 and 2026. The corresponding dry-year demand increment of 49Ml/d is represented by the broken red line which also incorporates 5% “headroom” to allow for relatively short-period contingency peaks. The top line reflects additional demand growth arising from climate change, estimated at 3% overall for the plan period, giving an out-turn demand of 797Ml/d. Adding 8Ml/d for agricultural irrigation gives the aggregate out-turn of 805Ml/d.
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A Water Resource Strategy for Kent>> 5 The water company perspective
5.1 CPRE Kent’s interpretation of the supply profile represented by the blue line in Figure 13 is calculated from the aggregate deployable drought output for all surface and groundwater sources operated by the constituent water companies, and is taken as being constant at 765Ml/d up to 2010. This gives a “starting” surplus of 40Ml/d, a figure which seems to be broadly consistent with the EA estimate for the dry year critical period balance for 2000/01. The interval from 2010 to 2015 is marked by the decrease in deployable output required of the companies in compliance with EWFD and Habitats Directive objectives. Pending final determination by the EA, this has been taken at a nominal minimum value of 50 Ml/d. The later years of the plan period feature the two reservoir schemes which at present constitute the key elements of the water companies’ strategies.
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A Water Resource Strategy for Kent>>
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A Water Resource Strategy for Kent>> 5.2 It is envisaged that the proposed Broadoak reservoir, near Canterbury, will be pump fed from the River Stour, but two previous attempts to promote similar schemes have failed. The more recent of these was in 1990/91, with a design drought output of 40 Ml/d, and was abandoned in recognition of the restrictive river flow conditions imposed by the EA in order to protect a range of environmental and water-use criteria. Fifteen years on, and with CAMS delivering considerably tougher environmental targets, there is even less likelihood of a successful promotion. Any assessment of Broadoak will also need to take account of the increasing weight of historic evidence pointing to a progressive decrease in the average annual flow of the Great Stour, corresponding to a loss of more than 15% over the period 1965-2000. (A recent update using the records for 2001-04 suggests that, millennium floods notwithstanding, the average has continued to decrease.) Other studies involving comparisons between the late summer “base- flows” recorded at Horton and Wye between 1965 and 2004 (Appendix I) indicate losses of more than 50% in the discharge of the chalk springs which sustain the river above Canterbury. If we project the current trend, the conclusion could be drawn that, by the time Broadoak is due to come into operation, there will be virtually no natural spring flow entering the river between Wye and Canterbury during the late summer months.
5.3 Unfortunately, the CAMS proposal to reduce borehole abstraction in this part of the catchment will achieve no more than a delay of a few years in the otherwise uninterrupted decline of the river. As to the most likely cause of this flow loss, we can look to the 105-year record for rainfall at Canterbury (Appendix I), the latter half of which shows a decrease of 60mm in the average annual total — a loss of approximately 9%. At the same time, average annual temperatures have risen, with corresponding increases in water loss by evaporation and plant transpiration, all pointing to climate change as the principal agency. And if we accept expert opinion on the subject, the conclusion is that we must expect the progressive decrease in effective rainfall to continue indefinitely. By the end of the plan period there may not, therefore, be sufficient flow in the river to sustain Broadoak storage at the levels required to keep pace with the growth in demand, or even yield sufficient to compensate for the loss of borehole output.
5.4 Most of the estimates derived for Figure 13 rest on some important simplifying assumptions and the forecasts are therefore conjectural. They serve, however, to demonstrate the degree of uncertainty with respect to both future demand and the effectiveness or otherwise of the schemes earmarked so far for resource development. We have to conclude that, in almost any event, the combined impact of planned growth, climate change and compliance with new environmental quality targets creates a substantial supply deficit from around mid period onward. Even assuming that the proposed new reservoirs deliver their full design outputs — and this is very much in doubt — they will not match the scale of the deficit that seems certain to develop. In effect, under this regime, the supply/demand balance will, in the space of approximately 10 years, have switched from a 40Ml/d surplus to a deficit of equal magnitude.
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A Water Resource Strategy for Kent>> 6 Planning for growth – a CPRE Kent strategy 6.1 Policy objectives From the CPRE Kent standpoint, the sustainable management of our county’s water resources is a prerequisite for the protection and enhancement of the quality and diversity of our rural environment. The key objectives are: ❏ To campaign for the adoption of strategies which: ● Encourage prudent and efficient use of water ● Ensure continuity of supplies for communities throughout the county ● Represent best value for consumers ● Enhance the conservation, amenity and recreational value of river and wetland environments ● Are fully compatible with other aspects of water and environmental management ❏ To support and promote the environmental objectives of the European Water Framework Directive and Habitats Directive ❏ To promote education in the conservation and sustainable use of Kent’s water supplies ❏ To provide a water resource management perspective for CPRE initiatives and responses on all relevant aspects of planning and development in the county.
6.2 Facing the future 6.2.1 We have seen that the current balance of resources in Kent is, for all practical purposes, in deficit, with no scope for further development of groundwater resources on the scale required to meet the anticipated demand growth. In fact the EA has, since 1993, maintained a general presumption against the grant of licences for any further increase in abstraction for consumptive purposes (including public supply) from the major aquifers (i.e. the Chalk, Lower Greensand and Hastings Beds). If anything, we must expect, over the next 10 years or so, to see a material reduction in the quantities pumped each year from the Chalk as part of the effort to improve the regime of the streams and wetland areas fed by spring flow from the North Downs.
6.2.2 The prospect for the development of new supplies from Kent’s rivers is little better, particularly in the light of recent drought experience and the accumulating evidence of progressive depletion of the baseflows of the Great Stour and other spring-fed water courses. For much of the county, winter rainfall has frequently failed to support the rates of pumping required to replenish the larger off-stream reservoirs — this must raise doubts as to the viability of the proposed Bewl Water and Broadoak schemes. It would seem to follow from this that any strategy developed for the county should have a much greater emphasis than hitherto on making better use, and re-use, of existing supplies. Should these fail to meet demand growth, the best recourse may then be to transfer raw water from neighbouring — or even distant — regions, taking advantage of existing trunk links and interconnected waterways. All this could be managed in conjunction with the output from reservoirs part fed from river sources, wherever the required winter replenishment rates can be achieved without detriment to the wider environment.
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A Water Resource Strategy for Kent>> 6.3 We envisage a three-part strategy, comprising: ❏ Water efficiency measures, including further leakage reductions, demand management and water conservation, underpinned by universal domestic metering ❏ Waste water re-use, both direct and indirect ❏ Strategic inter-regional raw water transfers, combined where appropriate with regulating storage
These elements should together provide sufficient scope and flexibility to satisfy demand growth for the plan period.
6.4 Water efficiency 6.4.1 Figure 14 shows the components of domestic water use in England. Unmetered consumption in Kent averages between 160 and 180l/h/d (2003/4 figures), slightly less in the east of the county. Corresponding metered rates appear to be coming out 10-12% lower, at around 150l/h/d (Ref 14). Higher gains may be possible at times of peak demand, which makes the case for more general metering beyond the current 25-30%. There are clearly savings to be made in regulating the use of water for discretionary and non-essential purposes, with an important secondary benefit in encouraging greater awareness of the value of water conservation and the avoidance of wastage in the home and garden. For the average household, conversion to metering generally means lower bills for both supply and waste water services. Usage can be further reduced by water-saving installations, including dual-flush toilets, low-head showers, grey-water re-use systems and rainwater capture in the garden (Ref 15 and Appendix II).
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A Water Resource Strategy for Kent>>
6.4.2 Taken together, measures such as these can reduce the level of domestic consumption by around 20%, assuming that the property has a metered supply with a tariff structure which rewards prudent use at times of peak demand. Unfortunately, although the benefits of water efficiency should be beyond dispute, little progress has yet been made in putting the necessary provisions into effect, and each passing year adds another 2Ml/d to Kent’s total public supply commitment. None of this is subject to any obligatory water conservation conditions in the grant of planning or building consents. Furthermore, although most water companies have plans to increase meter coverage over the next 25 years there are, according to the EA, some that remain to be convinced with respect to the savings in water that can be achieved. It has been made clear to these companies that they are expected to work together to develop tariff structures that help save water while protecting vulnerable customers. In the meantime, Folkestone and Dover Water Company’s success in securing “Water Scarce” status may encourage other undertakings to follow a similar course. The company’s own expectation is that 90% metering of their supply area will bring a reduction in demand of between 11 and 16%.
6.4.3 Some further impetus could also come from the Singleton (Ashford) tariff trials now being set up by KCC in collaboration with Mid Kent Water, the EA and Hillreed Homes. The objective of this is to assess the effectiveness of metering in conjunction with water efficiency features and a seasonal tariff regime. The trials will involve 250 new houses, constructed over
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A Water Resource Strategy for Kent>> a five-year period, the first 50 houses metered but without the specified efficiency fittings (the control group). A final report is expected in 2010, with an interim report in mid 2007. CPRE Kent is of the view that while this will no doubt provide valuable operational and management experience for future tariff setting, there can be no justification in further delaying what has now become an urgent need for the grant of planning/building consent for all new properties to be made conditional on the installation of standard water efficiency fittings.
6.4.4 Distribution leakage has been reduced substantially in recent years, but the 2004 review of water company water resources plans (Ref 18) showed that some in the South East are still failing to achieve Ofwat targets — there are supply areas in Kent where losses average more than 150 l/property/day. The call has now gone out to companies throughout England and Wales to improve overall leakage control performance.
6.5 Waste water re-use 6.5.1 CPRE’s 1993 strategy Water for Life included an assessment of the economics of water supply. This concluded that planned water re-use, both within individual properties and on the community scale, represented a cost-effective option as an infrastructure component of large-scale developments, tailor made, it would seem, for the Thames Gateway and Ashford. A similar conclusion was reached by the NRA in 1994, both direct and indirect effluent re-use options being seen as having “considerable potential”. And on the basis of the few studies completed by that time, they were judged to be relatively cheap to implement and without significant environmental impact.
6.5.2 It has been estimated that about half of all waste water processed by Kent’s treatment works is discharged to sea without making any further contribution to the supply or environmental needs of the county. The Margate/Broadstairs scheme is a recent example, one that has been the subject of much public debate and media interest (Appendix III). It involves the disposal to sea of up to 20Ml/d of treated waste water that could be further treated and put into supply as a wholly sustainable resource in an area facing an increasingly severe deficit — and the capital expenditure would be no more than that incurred in its disposal. It is, in other words, cheaper to use it than throw it away. It also has one special advantage over many conventional supply options: it can be phased in to match the rate of demand growth.
6.6 Raw water transfers Although water is generally perceived to be a substance which is expensive to move around, there are many instances of inter-basin and interregional transfer schemes which have proved to be competitively cost effective. Examples have also been included as potential components of a national strategy (Ref 7), making use of existing water courses and trunk mains, and they serve to illustrate how demand growth in the South East could be met by means of links from sources in north Wales, the Midlands and the North East. They are, for the most part, aimed at supply areas in East Anglia and the London Basin. In the latter case they include the construction of a south-west Oxfordshire reservoir of around 150 million cubic metres capacity and with a design drought output of 350Ml/d, fed from sources in the Thames and Severn catchments. Presumably, the London Ring Main could now be used to provide the final link in a “knock on” transfer into Kent. There are schemes already in operation which
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make use of the British Waterways canal network to provide inter-basin transfers, augmenting supplies for water companies in some cases over distances of more than 100km.
6.7 CPRE Kent’s plan for all seasons 6.7.1 Figure 15 shows the forecast demand trend matched against a resource management strategy comprising the elements outlined in Section 6.3. It requires that the earliest opportunity is taken to implement a programme of effective demand management measures, including the formulation and enforcement of provisions for domestic water conservation via planning control and building regulations for all new dwellings. This should be underpinned by compulsory metering, with appropriate tariffs, for all supply areas in Kent. This will in turn require the county to be declared a “Water Scarce” area. Given this, the demand-growth anticipated under the South East Plan could be reduced by at least 15% (with an underlying 5% reduction over the same period for existing households). This would help to establish a more favourable balance ahead of the mid-period cut-backs in output from the water companies’ groundwater sources. And these could be adequately covered by the phased introduction of waste water re-use, initially drawing on the Thanet and Ashford discharges. The period from 2006 to 2015 would then allow some breathing space for a full evaluation of the Bewl and Broadoak options alongside the alternatives of further re-use or strategic raw water transfers from the Midlands and/or Thames region.
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6.7.2 The schedule would also easily accommodate the schemes identified in the Ashford Integrated Water Management Study (Ref 16). This includes: ❏ Indirect effluent re-use ❏ Water efficiency and demand management ❏ Rainwater capture and grey-water recycling
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A Water Resource Strategy for Kent>> ❏ SUDS (sustainable urban drainage systems) ❏ Ecological water management options One example of the last category can be found in the scheme for headwater balancing storage proposed for a site in the floodplain of the East Stour. This tributary of the Great Stour carries a substantial flow during the winter, the record for 1980-2000 showing an average of approximately 100Ml/d for the period October to March. It constitutes a resource which could be exploited to support a multi-purpose balancing reservoir of sufficient capacity to serve a range of water management functions.
6.8 Drought management Kent’s recent experience of winter hosepipe bans and restrictions on non-essential uses has highlighted the shortcomings of the existing supply strategy. Climate change forecasts point to an increase in the frequency of intense and protracted droughts, and such events cannot be managed effectively by recourse to supply restrictions and the removal of controls that have been put in place expressly to protect rivers and aquifers from over-abstraction at times of low flow and depleted water table levels. The water companies now have a statutory responsibility to prepare drought plans as adjuncts to their annual Water Resource Management Plans. CPRE Kent is of the view that these should place much less reliance than hitherto on the suspension or downgrading of river flow or level conditions or other environmental safeguards. Such expedients must now be seen as wholly at odds with the aims of the Catchment Abstraction Management Strategy as the instrument of EWFD and HD. Many of the more extreme drought emergency measures can be avoided with a management strategy that is inherently sustainable and has the flexibility to accommodate the demand peaks that we are warned to expect as increasingly common features of our climate in the South East.
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A Water Resource Strategy for Kent>> 7 Summary and conclusions
7.1 It is clear to CPRE Kent that the county faces an unprecedented increase in the stress on its indigenous water resources resulting from: ❏ Demand growth accompanying planned housing development ❏ Climate change, which will reduce effective rainfall and increase peak demand ❏ The need to reallocate a substantial proportion of existing resources to the RBMP (CAMS) programmes for achieving environmental quality targets in compliance with EWF and Habitats Directives.
7.2 Levels of groundwater and surface water abstraction are now acknowledged to be unsustainable. The county does not, therefore, have the resources to cover the demand/supply deficit now forecast to accrue over the next 20-25 years.
7.3 Current wastage levels are unacceptably high, with more than half of the county’s treated waste water pumped to sea.
7.4 Existing management strategies rely almost entirely on the creation of additional reservoir capacity, with design outputs (yields) that cannot be sustained without drawing heavily on Kent’s already depleted rivers, some of which have been identified as falling below EWFD/HD environmental quality target levels.
7.5 There is a low level of awareness of the severity of the impending resource deficit and the consequent need for early and decisive corrective action by the water companies and regulators.
7.6 CPRE Kent is of the view that there is an increasingly strong case for a Kent-wide strategy transcending water company boundaries, one which is environmentally sustainable and delivers best value for money for consumers and the community at large.
7.7 Delivery may require the creation of a body with the authority and resources to formulate an optimum strategy and direct the water companies in its implementation.
7.8 The proposed CPRE Kent strategy would comprise the following elements, scheduled and implemented as shown in Figure 16: ● Secure recognition of the most heavily stressed supply areas (including the Medway and Thanet areas of Southern Water Services and the Ashford and Canterbury areas of Mid Kent Water), and promote their designation as “Water Scarce” areas. This would be a prerequisite for compulsory metering of existing domestic properties ● All relevant planning authorities to make the grant of planning/building consent conditional on the installation of specified water-saving fittings, including, as a minimum, dual-flush toilets, low-head showers, low-flow taps, and, where feasible, rainwater-capture facilities. This much is already within the existing discretionary powers of the local authorities, and would not require further legislation. The condition could therefore be implemented forthwith
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● Water companies will continue with their leakage reduction programmes in accordance with Ofwat targets ● By 2010, establish facilities for the treatment of up to 40Ml/d of waste water to a standard suitable for either direct or indirect re-use for public supply within north and east Kent ● Within the same period, complete a pilot programme for evaluation of grey-water recycling as an option for incorporation as a district supply facility to supplement the existing water-efficiency initiatives ● At the earliest opportunity, initiate the evaluation of options for interregional raw water transfer (incorporating balancing storage as appropriate) in cooperation with Thames and Midlands water companies and British Waterways, with a deadline not later than 2020. The design capacity should be sufficient to cover supply/demand deficits arising in the Thames Gateway area. This could be followed or paralleled by a second phase of waste water re- use.
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7.9 In formulating our strategy, we have endeavoured to frame the main proposals as positive and, hopefully, constructive contributions to the wider debate on the management of water resources in the South East. This is an issue which has come to be seen as having a direct bearing on the sustainability of the Government's growth plans for the region. While having a necessarily local perspective, we hope that this strategy will be seen as equally appropriate as an element of a broader, regional, water resource strategy.
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Glossary Abstraction The removal of water from any source (e.g. a river, spring or borehole) Aquifer A permeable geological formation capable of storing and transmitting water in significant quantities Aquifer recharge Replenishment of aquifer storage by rainfall or snow melt Baseflow The proportion of a river’s flow that originates as spring discharge or seepage from groundwater Biodiversity A measure of the number of species represented in a particular plant or animal community CAMS Catchment Abstraction Management Strategies Catchment The area of land contributing flow to a particular river Conjunctive use Combined use of different sources of water Consumptive use Use of water where a significant proportion is not returned either directly or indirectly to the source of supply Defra Department of Environment, Food and Rural Affairs Demand management Measures that serve to control or influence the consumption or waste of water Deployable output The reliable yield of a source of supply, taking into account all material constraints, including licensed abstraction rates and conditions, pump capacities, water quality, aquifer properties, treatment plant and distribution mains capacities Drought A general term for prolonged periods of below-average rainfall, resulting in low river flows and/or reduced groundwater recharge, and imposing significant strain on water resources and the wider environment Drought order A means whereby, for reasons of exceptional shortage of rainfall, water companies and/or the Environment Agency can apply to the secretary of state for the imposition of restrictions on the use of water, or which authorises abstraction in excess of existing licensed maxima Effective rainfall The proportion of rainfall remaining after allowance for losses by evapotranspiration, and which thereby constitutes a gain to the resource Effluent The liquid waste from industrial or agricultural sources or from sewage treatment works Flood plain An area of land periodically inundated at times of high river flow Flow duration The period of time, expressed as a percentage of a total year’s flow, during which a river exceeds a given rate. (For example, the rate which is exceeded 95% of the time is defined as the 95 percentile flow) Groundwater Water contained within the saturated zone of an aquifer HD Habitats Directive Habitat A geographic area occupied by and supporting a species or community Hands-off flow A condition attached to abstraction licences, representing the rate of flow below which abstraction is not permitted Hydrograph A diagrammatic representation of variations in the flow or level of a river or other body of water Impoundment A dam, weir or other work impeding or obstructing the flow in a water course Ml/d Megalitres (millions of litres) per day Mm3 Million cubic metres Ofwat The Water Services Regulation Authority, which regulates the water and sewerage industry in England and Wales
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Permeability The capacity of an aquifer to convey water Potable water Water of a suitable quality for drinking Precipitation Deposition of atmospheric moisture, including dew, hail, rain, sleet and snow Pumped-storage reservoir Storage primarily dependant on replenishment by pumped abstraction from a water course RMBPs River Basin Management Plans Soil moisture deficit The amount of rainfall required to restore a soil to its normal “field” capacity Storage coefficient Corresponds to specific yield or effective porosity and represents the quantity of water that can be obtained from a given volume of aquifer. It is generally expressed as a percentage (values for unconfined chalk generally fall between 1% and 2%) Sustainable development Development that meets present needs without compromising the scope for future generations to meet their own requirements Transpiration The process by which water taken up by plants is returned as water vapour to the atmosphere Watershed A line of separation dividing the precipitation on adjoining catchments and which directs the resulting runoff accordingly Water table The free surface of the saturated zone of an unconfined aquifer Wetland An area of low-lying land where the water table is at or near the surface Yield The reliable rate at which water can be drawn from a source of supply.
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References
1 Environment Agency, Water Resources for the Future, March 2001. 2 Environment Agency, European Water Framework Directive; Guiding Principles on the Technical Requirements, August 2002 3 Environment Agency, Medway Local Environment Agency Plan — Environmental Overview, January 1999 4 Geological Survey Memoir, The Water Supply of Kent, 1908 5 Department of the Environment, Using Water Wisely, 1992 6 CPRE, Water for Life, 1993 7 National Rivers Authority’s National Water Resource Strategy, Water, Nature’s Precious Resource, March 1994 8 Defra, Directing the Flow, Priorities for Future Water Policy, November 2002 9 Environment Agency, Catchment Abstraction Management Strategies, Managing Water Abstraction, July 2002 10 Environment Agency, Habitats Directive Guidance Notes (chapter 4 and appendix 4) 11 Environment Agency, Water Resources for the Future, annual reviews 2004 and 2005 12 KCC/Medway, Consultation Document, South East Plan: Employment, Housing and Infrastructure in Kent, September/October 2005 13 Environment Agency, North Kent and Swale Catchment Abstraction Management Strategy, April 2004 14 Environment Agency, Review of Water Company Water Resources Plans, 2004 15 Building Research Establishment, Ecohomes Guidance and Environmental Ratings, April 2006 16 Environment Agency (Black and Veatch Consulting Ltd), Ashford’s Future, Integrated Water Management Study, Final Report, August 2005 17 Environment Agency, Water Resources for the Future, annual review 2005 18 Environment Agency, Review of Water Company Water Resources Plans, November 2004.
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Appendices Appendix I: Climate change indicators
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Appendix II Building Research Establishment (BRE) guidance on domestic potable water use The BRE’s Ecohomes guidance (Ref 16) provides a scale of water-usage ratings for each of the main categories of installation and arrives at corresponding estimates for total consumption. Its aim is to encourage improved water efficiency in the home, and it is applicable to both new builds and retrofitting in existing properties. The table provides a simplified summary of the BRE procedure. Total high-level usage comes out substantially higher than the current average per capita consumption of 160l/head/day, but even using the latter figure, a relatively modest target of 100l/h/d for low-level usage would represent a reduction of nearly 40%.
Calculation of internal potable use
Installation Water use rating usage: ave no of usage: type litres/ head/ operations l/head/d operation per day
WC High 10 6 60 Medium 5 6 30 Low 3 6 18
Wash basin Standard 1 12 12 taps Flow regulator 0.5 12 6 Auto shut 0.5 12 6 Aerating 0.5 12 6
Shower High 110 0.7 77 Medium 50 0.7 35 Low 25 0.7 18
Bath Large 100 0.3 30 Standard 80 0.3 24 Small 60 0.3 18
Kitchen sink No dishwasher 17 1 17 With dishwasher 12 1 12
Dishwasher Typical practice 25 0.25 18 Best practice 12 0.25 12
Washing Typical practice 60 0.30 6 machine Best practice 40 0.30 3
Total High 220 Low 87
The guidance note also includes calculations for grey-water recycling and rainwater capture.
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A Water Resource Strategy for Kent>> Appendix III Summary of a representation by CPRE Kent with respect to Southern Water’s application to construct a twin waste-water and effluent pipeline between the Margate headworks and the Weatherlees waste-water treatment works. The full version of the representation is available from CPRE Kent. ❏ The scheme provides for the transmission, over a total distance of about 24kms, of waste water from Margate/Broadstairs to the Weatherlees waste-water treatment plant, from which it would be returned to the coast for discharge at sea, having been treated to standards compliant with the European Urban Waste Water Directive. The proposed disposal to sea of up to 20Ml/d of treated effluent constitutes unacceptable wastage of a scarce and strategically valuable resource in a region subject to a progressive deterioration in the water supply/demand balance and increasing stress on the environment. The scheme also conflicts with Southern Water’s own declared policy of supporting the re-use of treated effluent as a key element in the integrated management of the region’s water resources (see South East Water Resources Forum Annual Report 2003, page 35, ‘Water supply and sewerage — a water company perspective’). ❏ CPRE Kent therefore recommends that the application be amended by removal of the return (Weatherlees to Margate) pipeline works and substitution of a facility for discharging the treated effluent to the River Stour as a means of augmenting river baseflow, with the possibility, in due course, for re-abstracting a proportion for public supply.
In evaluating the suitability of this potential arrangement, the Environment Agency (EA) will be able to draw on its own experience as the consenting authority for the Langford effluent recycling scheme in Essex. This is the result of 10 years of research and development by Essex and Suffolk Water and is now a fully operational public supply facility with a capacity of 40Ml/d, using treated waste water fully compliant with UK and European water supply and environmental standards. The discharge consent for the Langford scheme incorporates schedules relating to secondary treated sewage effluent in accordance with Urban Waste Water Treatment Regulations, and includes provisions for removal of phosphates, nitrates, ammonia, oestrogens and specified pathogens. The River Chelmer — the receiving water for the consented discharge — has an average annual flow at Langford of 220Ml/d. This includes an existing 11% of effluent loading from other sources, and, with the additional maximum daily discharge of 40Ml/d (DWF of 30 Ml/d), this would give a total loading of 25%. (See Walker, D: The Promotion of a Planned Indirect Waste Water Re-use Scheme in Essex. J. Ch. Instn Water and Environmental Management November 2001.) No corresponding direct measurements of flow are available for the Stour at Weatherlees, but the long-term record for the gauging station at Horton, upstream of Canterbury, gives a figure of 270Ml/d for the annual average. Allowing for tributary inflow and a proportion of treated effluent entering the intervening reaches of the river between Canterbury and Weatherlees, the discharge from the treatment works would probably amount to an additional concentration of not more than 10%. To judge from the Langford scheme, the technology now exists for treating waste water to the highest environmental and drinking-water standards under UK and European law. There would therefore seem to be neither need nor justification for the scheme proposed by Southern Water. We would welcome the opinion of the EA as to whether there would be any
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A Water Resource Strategy for Kent>> reason, at least at first sight, as to why a treatment and re-use facility on the lines of the Langford model could not be successfully incorporated in the Weatherlees extension. Much, if not all, the essential groundwork appears to have been completed by Essex and Suffolk, and the necessary additional conversion works would, presumably, not add significantly to the programme. We recommend that Southern Water be directed to engage with the EA in the formulation of a strategy for the sustainable re-use of the Margate/Broadstairs water, with special attention being given to the potential for addressing peak demand growth in the Thanet area. Consideration should also be given to the scope for using part of this resource for augmenting summer-period flows in the River Stour.
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KENT A Water Resource Strategy for Kent
By Graham Warren