Hydrogeology WorkshopIntroduction to Hydrogeology (6)

Groundwater Flow

How and why does it get out?• Water table is intercepted by the ground-surface - pretty

obvious really.

But what else can encourage groundwater to discharge at the surface?

– Boundaries and Barriers

• Impermeable geological layers;

• Faulted boundaries

Hydrogeology WorkshopIntroduction to Hydrogeology (7)Hydrogeolgy of the Ridge Area

What does all of this mean for the Sandstone Ridge Area?

We will use what we have learnt to build a conceptual model which illustrates how this applies to the Sandstone Ridge Area.

Hydrogeology WorkshopIntroduction to Hydrogeology (7)Hydrogeolgy of the Ridge Area

Recharge. Bigger arrow,

more recharge

Groundwater in perched aquifer quickly discharges to springs, streams and ditches

Water tables are established in small perched aquifers and the main Sandstone aquifers.

Most of the groundwater in main aquifer flows from east (high area) to west (low area) where much discharges to rivers and streams

A small amount of groundwater flows toward the east and could come in contact with the salt

To the east, the Sandstones are deep beneath the mudstones. Groundwater is old, stagnant and poor chemical quality.

Hydrogeology WorkshopIntroduction to Hydrogeology (7)Hydrogeolgy of the Ridge Area

Boreholes, Wells and Springs....

• Where might they be?

• How much water will you get?

• Who might have one?

Hydrogeology WorkshopIntroduction to Hydrogeology (7)Hydrogeolgy of the Ridge Area

A A A A

A. Spring sources. Usually moderate yields for domestic/small community supply. Can produce high yield in places.

BB

B. Shallow wells/boreholes into small perched aquifers. Usually small yields. Mostly suitable for domestic supply.

C

C. Shallow wells/boreholes into extensive sands and gravel. Moderate yields (domestic) but could be high (aggregates industry/gen industry/community supply). However, contact with rock salt etc may cause quality problems especially if over-exploited/over-pumped.

DD1

D. Moderately deep boreholes into main Sandstone aquifers; fewer faults may mean lower yields but some sources may draw additional water from rivers if nearby (D1). Some public water supply boreholes are here.

E E

E. Moderately deep to deep boreholes into main sandstone aquifers. Faulting, fractures and fissures are common and yields can be very high. Most of the public water supply boreholes are here.

F

F. Very deep boreholes may generate decent yields (may also be artesian), but water quality is likely to be very poor. Very few, if any, water supply boreholes into the Sandstones here.

Hydrogeology WorkshopIntroduction to Hydrogeology (7)Hydrogeolgy of the Ridge Area

Distribution of water wells/boreholes from BGS records

Go to http://www.bgs.ac.uk/discoveringGeology/geologyOfBrita

in/viewer.html

(Follow instructions for showing locations at rear of handout )

Hydrogeology Workshop

Part 3

What’s on Your Door Step?

Hydrogeology WorkshopWhat’s on Your Door Step? (1)

• Sources of Information

• Records and Record Keeping

Hydrogeology WorkshopWhat’s on Your Door Step? (2)

Sources of Information:– Publications/BGS/Internet. Literature, Maps (geol, topo,

hydro), Borehole/well records, etc

– Regulatory Bodies. Environment Agency, Local authority (Env Health Dept)

– Water Companies. (UU, STW)

– Historical maps/ Estate records

– Local Groups. Local History, Regional Group Geol Soc

– Local Knowledge. Methods of engagement, Anecdotal, Press release, Internet.

– Other. Place names, road names, house names.

Hydrogeology WorkshopWhat’s on Your Door Step? (1)

Records and Record KeepingAn example well/borehole catalogue. Exercise using details from a

selection of actual borehole logs and maps to populate the catalogue.