O level Notes: Agriculture - Water conservation

There are various causes of water pollution that includes industrial wastes, sewage wastes, empty containers and soil erosion. When polluted, water will not be safe for use due to a lot of effects it may cause to people using it. Some of the effects of polluted water include death of aquatic life, outbreak of diseases, growth of invasive plant species and blockage of water channels. However, people can employ a number of strategies in order to reduce the pollution of water. Methods that can be used includes proper disposal of litter, use of alternative litter management strategies, siting industries away from public water sources and setting restrictive rules and laws. The topic will also explain about the water legislation in Zimbabwe and the purpose of such legislations. 

Causes of water pollution

Industrial wastes

During manufacturing of various products, wastes are produced in form of solid particles, liquid or gas. The wastes may contain toxic chemical compounds and dirty matter and they can be flashed into rivers and dams thereby causing pollution.

Sewage wastes

Most toilet systems in urban areas are water systems and after flashing all the toilet wastes are drained towards sewage dams through pipes. Sometimes the sewage pipes may burst and the waste will flow into rivers, dams and wells thereby contaminating them.

Agro-chemicals and fertilizers

The chemicals and fertilizers that are applied during farming can be leached down towards ground water sources. More of this effect happen when there is heavy rain just after chemical or fertilizer application. Also fertilizers and chemicals can be eroded to other water sources through water runoff. Fertilizers and chemicals have toxic chemical compounds which will make water unsafe for use.

Empty containers

When the litter is thrown everywhere on the land, it will be washed away by water runoff and will be deposited into the streams, rivers, dams and wells. Empty containers include empty food tins, chemical bottles and plastics. Algae will grow on these containers and becomes breeding places for pathogens.

Kitchen wastes

Fruit peels and seeds which are thrown on the ground will be washed away into the rivers and dams thereby polluting the water. Also kitchen left overs like vegetable pieces, sadza and rotten food that are disposed on open ground will be washed away into rivers and dams by rain water.

Domestic use

People tend to wash their clothes, bodies and plates in public water sources like dams and rivers. By so doing, the water is made dirty and will not be clean and safe for use.

Soil erosion

During rainy season, the soil is washed away into streams and rivers and it will mix with water thereby making it dirty and muddy.

Animal wastes

Animals usually pass urine and dung into the water in rivers and dams when they are drinking or crossing. Also the waste may be left on land and will be washed into the rivers during rain through running water.

Effects of pollution on agriculture production

Death of aquatic life

Agro-chemicals such as herbicides and pesticides have toxic effects to water living animals such as fish, crocodiles and hippopotamus. They may get sick or die due to contact with chemicals or by drinking that water.

Outbreak of diseases

Dirty water promote the breeding of pathogens and vectors such as mosquitoes and house flies. The vectors will then transmit pathogens like protozoa and bacteria to people thereby causing sickness. Example of diseases caused by pathogens that breed in dirty water include cholera, dysentery, typhoid, and diarrhoea.

Growth of invasive plant species

The eroded fertilizers will reach the water bodies thereby supplying with abundant nutrients for over growth of water loving weeds. These will occupy space that should be holding water leading to a reduction in water holding capacity of dams and rivers.

Shortage of water to people downstream

Some pollutants such as soil may cause siltation in the long run. This will make dams and rivers so shallow thereby reducing water flow. This will reduce water available for use by people in the surrounding area.

Blockage of water channels

Drainages may be blocked and this will cause water logging in some areas. Also irrigation and domestic water pipes may be blocked which may result into bursting of pipes and loss of large amounts of water.

Reduction of crop quality

Crop quality can be greatly reduced when the water being used is polluted. Some chemicals react thereby hindering the absorption of necessary nutrients by the plants. In this case, the crop growth is retarded.

Ways of reducing water pollution

Proper disposal of litter

Organic and inorganic litter must be disposed in the areas well designed for that purpose only. The rubbish area should be far from residential area and clean water sources in order to avoid the risk of contamination.

Use of alternative litter management strategies

Various methods available for litter management include burying, burning, reuse and returning to the manufacturer among others. The methods to be given first preference are those with minimum chances of causing water pollution. In this case reuse is most recommended.

Fetch the adequate amount of water for use

Instead of washing and bathing in rivers and dams, people may fetch some water and do it outside and this will avoid polluting the whole water body.

Siting industries far from water sources

In most industries, the wastes are channeled towards perennial rivers and streams in order to flow away which is not good. When they are sited far from water sources the chances of pollutants reaching water sources will be slim as they tend to construct disposal structures such as dams and landfills.

Minimum use of agro-chemicals in farming

Farmer can practice organic farming such as use of compost manure, cultural weed control like crop rotation and planting cover crops against pests. This will reduce pollution of underground and surface water sources through chemicals and fertilizers.

Setting restrictive laws and rules

The rules and laws should be put in place by the government and the citizens must abide with them in order to reduce pollution. Rules and laws will be enforced by use of penalties for the people who act against them.

Water treatment

Water can be treated to kill the gems and trap the dirty material at the base of the tank. This will make it clean and safe for human and animal consumption.

Educating people

People should be educated about the dangers of polluting the water. They should also be taught about the ways of reducing water pollution so that they will practice it in their localities.

Water legislation

There are laws which were established to govern the use of water for any commercial purposes. The Water Act (Chapter 20: 24) is the operating law which regulate the utilization of major water resources with sustainance. The government of Zimbabwe through its department of ZINWA is able to control the use of water from dams, rivers, lakes and underground. In order for one to make use of public water for commercial purposes such as irrigation, a permit is issued by ZINWA upon legislation. The permit is renewable after a certain period and the concerned person or company have to pay a reasonable amount of money in order to acquire that permit.

The purpose of Zimbabwe National Water Authority (ZINWA)

• To ensure clean, safe water is supplied to the public places such as schools, hospitals, cities and residential areas.
• They manage surface and underground water resources and distribute it to all water requiring sectors equitably.
• They monitor the quality of water resources by ensuring minimum or no pollution is caused.
• Building of water conservation structures such as dams and reservoirs.

water legislation in Zimbabwe.

Here is what we discussed in this topic

• Water conservation is the protection of water against unnecessary use and loss of water.
• Water pollution is any activity that results into dirtiness of water.
• Water pollution is caused by several human activities including the following;
• Industrial processes resulting into emission of wastes into water bodies.
• Sewage wastes that may contaminate clean water when the pipes bursts.
• Fertilizers and chemicals that are used in farming may be leached and eroded into water sources.
• Domestic use of water contaminates water through bathing and washing clothes in rivers and dams.
• Water pollution have got detrimental effects to the agricultural production.

• It causes death of aquatic life such as fish and crocodiles.
• Water pollution may cause the outbreak of diseases such as typhoid, cholera and dysentery to human beings.
• It may cause the growth of invasive species that results into reduction of volume of water in water bodies.
• Water pollution can be reduced using several ways such as proper litter disposal, fetching the required amount of water for use, siting industries away from water sources, setting restrictive rules and laws and also by water treatment.
• Water legislation is there to govern and control the use of water in Zimbabwe.
• The department of ZINWA works on behalf of Zimbabwean government to control the use of public water sources for commercial purposes.
• ZINWAserves the following purposes;
• To ensure supply of clean, safe water to all public places like schools, hospitals, cities and residentials.
• To manage all surface and ground water resources and to ensure they are distributed to all water requiring sectors equitably.
• To monitor the quality of water resources by ensuring minimum or no pollution is caused.

Definitions

• Aquatic- organisms that can live in water throughout the entire life.
• Toxic- refer to the chemical levels that can cause harm to the life of organisms.
• Invasive- plant that invade and occupies the space where it is not wanted because it causes unfavorable outcomes.