Rivers: People and Management

Reasons for the Increase in the Use of Water

- domestic use

- industrial use

- agricultural use

- leisure use

Why has domestic use increased the use of water?

- The rising standard of living, from development, increases domestic use of water

- More houses with piped water, flush toilets, showers and baths, washing machines, and even swimming pools → higher water consumption.

Why is more water being used agriculturally?

- rise in agricultural productivity needed to feed a growing population → increases water use for irrigating crops and drinking water for livestock

Why has the use of water increased in the industry?

industrialisation from development → factories consume lots of water for cooling machinery, generating goods and electricity

Why has the use of water increased in leisure?

- increasing population → increasing use of water for sport fishing, sailing, watering golf courses

What is water demand and supply?

- Water demand: need of water for various uses

- Water supply: meeting demand by tapping into sources

What does it mean by water-deficit, water-surplus and water-neutral areas?

- Water-deficit areas: areas where water demand exceeds supply

- Water -surplus areas: areas where water supply exceeds demand

- Water-neutral areas: areas where water demand and supply are roughly the same

Why are some areas in a water-surplus?

- remote, mountainous regions with high annual rainfall

- few people, low demand

Why are some areas in a water-deficit?

- little annual rainfall

- large populations and rising development

Sources of Water Pollution

- Agriculture

- Industry

- Domestic uses

Agricultural Water Pollution

- liquid from farm silage and slurry from farm animals enter rivers

- fertilisers and pesticides seep into groundwater

- deforestation → run off carries soil and silt into rivers → harms aquatic life and humans who drink the water

Industrial Water Pollution

- taking cooling water from river for electric power station and returning it at higher temperature → upsets river ecosystems

- spillages from industrial plants (oil refineries) → enter rivers

- toxic substances from working of metallic minerals and ore-processing → enter rivers

Domestic Water Pollution

- discharge of untreated and treated sewage from houses

- washing clothes and bathing in river → contaminates water

- emptying highly chlorinated water from swimming pools → contaminates water

What are the three main stages of managing the supply of clean water?

1. Collection

2. Treatment

3. Delivery

Sources of Water for Collection

- Rivers and lakes

- Reservoirs: artificial lakes from dam construction allowed to flood, water collected and stored behind dam

- Aquifers: underground porous rocks extracted by drilling wells or boreholes

Water Treatment

- chlorination: controls any biological growth (e.g. algae)

- aeration: removes dissolved iron and manganese

- sedimentation: removes suspended solids

- filtration: removes very fine sediments

- disinfection: kills bacteria.

Delivery (from Water-Surplus to Water-Deficit areas)

- by hand in plastic bottles (expensive, concerns with water quality)

- by buckets and containers (risk of pollution, time-consuming)

- by motor vehicles

- by tanker ships

- by long-distance pipelines and canals (expensive to install and maintain, leaks cause loss of water)

Consequences of Flooding

- Immediate effects: loss of life, diseases, property and crop destruction, homelessness, transport and communication disruption, loss of water supply and sewage disposal services

- Long-term Effects: replacement costs, remvoing deposited silt

What are the three types of action for flood control and management?

- Construction

- Adjustment

- Prediction

Construction

- building hard-engineering structures: dams, flood embankments (raised artificial banks), sluice gates, relief channels

- hold back or help safely dispose of floodwater

- expensive to build

Adjustment

- avoid or minimise potential flood damage

- soft-engineering: works with nature

- restoring a river to natural state, preserving marshes and wetlands (temporary stores of floddwater) on floodplain, having stricter planning controls that minimise building on the flood plain, encouraging flood insurance in flood-risk areas, better flood warning systems, publicising what to do in emergency

Prediction

- knowing how high or wide a river can become during flood conditions

- helps decide how high to build river embankments

- helps stop building of houses, factories and services in flood-risk areas

What is risk assessment?

- decision of which level of flood they should provide protection against

- cost-benefit analysis