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East Land Quality Forum

Richard Fry

Ely Golf Club

November 6th 2012

Hydrogeology of East

Anglia – An

Introduction

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East Land Quality Forum - Hydrogeology of

East Anglian

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East Land Quality Forum - Hydrogeology of

East Anglian

• Groundwater systems are complex and difficult to assess; they

are based on aquifer systems with complex and heterogeneous

geologies.

• A particular difficulty is that groundwater cannot be seen, and

groundwater flows cannot be measured directly.

• Thus, a comprehensive understanding of groundwater systems

can only be developed through targeted investigations, long term

monitoring and interpretation

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East Land Quality Forum - Hydrogeology of

East Anglian

• So we will be looking at are:

• Hydrogeology

• Groundwater Storage and Flow

• Primary Permeability;

• Secondary Permeability; Principal Aquifers;

• Secondary Aquifers;

• Geology

• Hydrology

• Rainfall, Runoff, Interflow, Recharge;

• Baseflow, Springs, Swallow Holes, Blow Wells;

• Abstraction

• PWS, Agricultural, Industrial, Domestic;

• Ecology

• Contaminant Transport potential

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East Land Quality Forum - Hydrogeology of

East Anglian

• The importance of groundwater is that it represents a vital

source of water for public and private supply.

• Some 45% of the water delivered by the various water users

within Anglian Region continues to be derived from groundwater

sources and thus 55% is sourced from surface water.

• The main aquifer systems across the region within which,

groundwater is stored are the Lincolnshire Limestone, the

Greensand, the Crag and, most notably, the Chalk, and these

underlie 55% of the area of the Region.

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East Land Quality Forum - Hydrogeology of

East Anglian

Some Useful Definitions:

Aquifer - A geological formation capable of storing and transmitting water;

Aquiclude - An impermeable geological formation incapable of transmitting

water;

Aquitard - A geological formation capable of storing water but which

releases stored water slowly;

Permeability - A measure of the ability of a geological formation to transmit

water;

Primary - Intergranular flow; (Sandstones, Alluvial Aquifers)

Secondary - Fissure flow (structured formations); (Limestone, Chalk)

Storage - A measure of the abstractable quantity of water stored in an

aquifer system.

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East Land Quality Forum - Hydrogeology of

East Anglian

Groundwater Flow

Governing Equation (Darcy's Law) Q=kAi

Where:

Q = Discharge (m3/day)

k = Permeability (m/day)

A = Area (through which flow takes place m2)

i = Hydraulic gradient (dimensionless)

Also:

T = Transmissivity (m3/day/m)

b = Saturated thickness (m)

Since T=k/b then Q=TiL (useful for back of an envelop calcs)

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East Land Quality Forum - Hydrogeology of

East Anglian

Chalk & Limestone

Transmissivity

High GW Level

m2/d

T=k/b

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East Land Quality Forum - Hydrogeology of

East Anglian

Transmissivity

Low GW Level

m2/d

Chalk & Limestone

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East Land Quality Forum - Hydrogeology of

East Anglian

Chalk & Limestone

Specific Yield = Vw/Vt

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East Land Quality Forum - Hydrogeology of

East Anglian

Geology

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East Land Quality Forum - Hydrogeology of

East Anglian

Cross

Sections

and

Buried

Valleys NEAC Project

Area

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East Land Quality Forum - Hydrogeology of

East Anglian

Section 3a

East

Upper Chalk

Crag

London Clay

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East Land Quality Forum - Hydrogeology of

East Anglian

Section 3.2b

West

Middle Chalk

Lower

Chalk

Drift

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East Land Quality Forum - Hydrogeology of

East Anglian

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East Land Quality Forum - Hydrogeology of

East Anglian

Hydrogeological

Processes East Anglia A – Recharge dominates

F – GW discharges to main rivers (baseflow)

G – Springlines along chalk feather edge

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East Land Quality Forum - Hydrogeology of

East Anglian

Hydrogeological

Processes East Anglia H – Till dominated area of low recharge

I – Stream headwaters on Till, limited to zero baseflow

K – Recharge dominant in Eastern Crag areas

N – London Clay margin, GW forced up into Crag

O – Restricted GW flow to East under London Clay

East

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East Land Quality Forum - Hydrogeology of

East Anglian

Hydrologic Cycle

The Anglian Water region is

one of the driest in the

country, receiving on

average only 600mm of

rain a year

Hydrology

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1961-2007 Long term average

(mm per year)

East Land Quality Forum - Hydrogeology of

East Anglian

Rainfall

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East Land Quality Forum - Hydrogeology of

East Anglian

1961-2007 Long term average

(mm per year)

Effective rainfall

(Rain – Evapotranspiration)

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East Land Quality Forum - Hydrogeology of

East Anglian

1961-2007 Long term average

(mm per year)

Groundwater recharge

(Infiltration to aquifers)

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East Land Quality Forum - Hydrogeology of

East Anglian

Total Natural Flow,

QN95

Ml/d

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East Land Quality Forum - Hydrogeology of

East Anglian

Congham Spring

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East Land Quality Forum - Hydrogeology of

East Anglian

Baseflow Influent and

Effluent

Streams/Rivers

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East Land Quality Forum - Hydrogeology of

East Anglian

There are over 8200

boreholes, wells and

springs licensed for the

abstraction of

groundwater in Eastern

England

Total licensed amount

is approx. 1560 Ml/d

Recent actual uptake

approximately, 875

Ml/d

Abstraction

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East Land Quality Forum - Hydrogeology of

East Anglian

Northern East Anglia

Chalk GW Abstractions

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East Land Quality Forum - Hydrogeology of

East Anglian

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East Land Quality Forum - Hydrogeology of

East Anglian

Water level

Ecology Flow

Chemistry

Define base

of wetland

Define strata

beneath

wetland

Drill to main

aquifer horizon

Define

connection

to aquifer

Characterise signal

beneath site

Characterise

signal attenuation Characterise

signal at

source

Ecological

Significance

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East Land Quality Forum - Hydrogeology of

East Anglian

East Wretham

Heath Dry Mere

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East Land Quality Forum - Hydrogeology of

East Anglian

East Wretham

Heath Wet Again

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There are 369

groundwater sources

used for drinking water

with source protection

zones in the east of

England:

Most are for public water

supply

East Land Quality Forum - Hydrogeology of

East Anglian

Drinking Water Source

Protection Zones

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East Land Quality Forum - Hydrogeology of

East Anglian

Hazards to

Groundwater

*Groundwater Forum

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East Land Quality Forum - Hydrogeology of

East Anglian

Groundwater

Protection *Groundwater Forum