1. What do these photos have in common?
Explain how
they link to the unit

2. Sources of Water

3. Rivers Reservoirs/Lakes Sources of Water Aquifers Seawater
Why used historically
Residence times
Poor water quality  urbanisation
Factors affecting suitability as a source of water
Times of surplus / deficit
Artificial construction
Benefits to flow regime
Factors considered when siting a reservoir
Environmental Impacts (Effects)
Case study of water demand (Devon / Cornwall)
Tidal Barrages
Sources of Water
Porosity & Permeability
Rock types (lithology)
Suitable geological structures
Consequences of over abstraction e.g. Subsidence, surface hydrology, ecology, saltwater incursion
Desalination
Cost?
Aquifers
Seawater

4. All in your notes: 1. Explain the qualities of a useful water supply
2. Explain how a useful supply controls the quality of life within a country
………….. and give one example of a region where it is holding back development

6. Factors considered when siting a reservoir
Topography
Geology
Catchment Area
Water Supply
Existing land-use
Pollution Risk
Sedimentation
Infra-structure

7. Environmental Impacts
Habitat Change
b. Changes in River Flow Regime
c. Sedimentation
d. Micro-climate

8. Water Demand: Case Study  Devon and Cornwall
Demand is > due to pop size and affluence
In summer Tourist No’s and evapotranspiration trans rate both >
Shortage of stores: Aquifers limited as most bedrock is crystalline granites and therefore impermeable.
Abstraction in large volumes from rivers limited as large rivers don’t exist
Seasonal demand is therefore met by surface stores from reservoirs that are in upland areas often in National Parks or areas of ONB.
Thus best sites are a compromise of best physical store available on the one hand whilst avoiding unacceptable environmental impact on the other.

9. Rivers
There are a limited number of large rivers in Devon and Cornwall reducing potential abstraction sites

10. Geology
The geology in Devon and Cornwall is mainly impermeable granite, reducing aquifer potential!

11. Tourism
Devon and Cornwall is a tourist honeypot – therefore numbers grow in
the summer > demand

12. National Parks and Areas of Outstanding Natural Beauty (AONB)
Much of the area is NP e.g. Exmoor and Dartmoor or AONB
Therefore compromise exists between reservoir sites that offer best potential storage VS minimal environmental damage!

13. e.g. Flooding of the Tryweryn Valley near Bala
Other conflicts of interest when finding reservoir sites to provide sources of water to populations
e.g. Flooding of the Tryweryn Valley near Bala
Village of Capel Celyn flooded
70 people lost homes
Resentment prevailed
Welsh Nationalist support >
“ Remember Tryweryn”
Lyn Celyn: Now fills the valley and provides
water for Liverpool

14. Another good link of this Case Study on youtube can be found here
Watch it in your own time!

15. But what made the Tryweryn Valley such a good site for a reservoir?
Access – not too remote (near to L’pool as mid-Wales.) For construction and transporting water after complete
Geology – Mainly impermeable mudstones, siltstones and grits
Prevents water loss.
Topography – Valley widens behind dam site to increase storage
Steep and deep valley: U-Shaped
Geology – Glaciation has caused
Steep and deep valley therefore increasing reservoir volume
Land Value –Low land value mainly upland hill farms
Catchment –High precipitation rate – as upland Wales has high rainfall therefore plentiful recharge
Geology – Rocks folded into a syncline structure -
Prevents water loss.
Topography – Contours close together – Steep sided valley and deep (look at heights!) – reduces surface area for evaporation
Narrow Dam Site - (800m) on flat U-shaped valley floor = stable
flat foundations

16. So what is the Land-use like now after the Dam was built and the lake (Llyn) Celyn flooded the Valley?
I can spot at least 6!