‘Human influence created The Broads and human influence is contributing to its destruction.’

Norfolk Broads

Location

Briefly…

• The Broads is a network of mostly navigable rivers and lakes

• The Norfolk Broads is the UK’s largest nationally protected wetland and an important area for wildlife.

• They were formed by people digging for peat during the Medieval times and where later flooded.

• nowadays they are used purely for pleasure and passengers are the boats’ main cargo.

Human impact on the broads

• eutrophication

• erosion

Human Process Threatening the Broads

Eutrophication is a process that is caused by human action (farming and sewage). It literally means ‘The Process of Making Too

Much Food’.

Human Process Threatening the Broads

Farmer puts fertilisers (NITRATES) on farmland to help crops to grow.

PHOSPHATES from human waste are discharged straight into the Broads from sewage works.

Human Process Threatening the Broads

Rain falls onto farmland and washes the nitrates into the broads. Phosphates from treated sewage is released into the broadland ecosystem.

Human Process Threatening the Broads

Both the nitrates and phosphates serve as a rich source of nutrients for plant life and especially algae. They multiply and die very quickly. The broads become covered in "algal blooms", where the top of the water is completely covered in algae.

Human Process Threatening the Broads

The accelerated growth of algae means that the oxygen levels in the water decrease rapidly, and the "algal blooms" block out the sunlight. This causes the death of many plants and animals.

Human Process Threatening the Broads

The huge numbers of algae die quickly and accumulate on the bed of the broad. The material formed is necron mud which continues to consume oxygen as it rots. This also fills up the broad, making it shallower.

Human Process Threatening the Broads

If this process is allowed to continue, the broad will eventually fill up with necron mud and disappear. In addition, tourist boats in the area can stir up the necron mud, which is rich in nutrients, which means the process of eutrophication is continued.

Human Process Threatening the Broads

Eventually the broad disappears completely, infilled by necron mud and dead animals. Vegetation succession then takes over the area.

This process can be stopped.

Nutrients washed off into the broads from farming - sewage

To many nutrients + sunlight = excessive growth of algae

Algea block out the sunlight and this kills the low water plants

Nutrients – phosphorus and nitrogen from decomposing swamp washed of into water in 1800

Sunlight

Weeds replace the low water plants

This creates suitable environment for fish

Chemistry of the water

• The chemical composition of each broad depends on the water which flows into them

• This determines the type and quality of ecosystem

• The amount of nutrients is different in isolated broads compared to broads that are downstream from populations where sewage is excreted.

Different environments

• This further affects the type of environments

• We can find clearer waters or/and brown turbid waters amongst the Norfolk Broads

Natural Process Threatening the Broads

Vegetation Succession is a natural process where dead plants lower the water level

and plants infill the Broads.

Natural Process Threatening the Broads

Large body of open water

Vegetation grows in a specific order at the

edge

Peat from dead plants

Natural Process Threatening the Broads

Vegetation grows further into the

broad

Amount of water in the

broad decreases

A new layer of peat builds up from dead

plants

Natural Process Threatening the Broads

The inevitable end to the whole process is that the broad completely

fills up and FEN CARR (woodland) takes over. The whole process only

takes 20 years.

Bank errosion

• Occurs because of the increased use of the broads for boating

• The wash from boats undercuts the river banks which release sediment into the streams

• Some eroded banks need to be protected by pilling

• Boats also stir up the bottom sediments leading to their movement downstream

• The broads are slowly filling up with sediment

• Constant siltation and eutrophication of the broads ha led to a loss of habitats for many species.

• Broadleaf plants – waterlily, watersoldier, hornwort

• These plants provide a habitat and sorce of food for many small creatures such as snails, beetles and larvae.

• In this way the first steps in many food chains are removed and lead to reduced numbers of fauna in the higher chain