WATER SUPPLY IRRIGATION AND DRAINAGE

Introduction

• Water is a very important natural resource.
• It is necessary for both crops and livest

Uses of water in the farm;

• Cleaning equipment.
• Irrigation in dry areas.
• Processing farm produce, for example, co
• Drinking by livestock and m
• Mixing agro-chemicals such as acaricide, fungicides and herbicides.
• Providing power in water mills to grind grain crop
• Cooling engines.
• Construction work.

Sources of Water in the Farm

Three major sources of water in the farm:

Surface water:

 Includes water from;

• Rivers,
• Streams
• Dams.
• Ground water:

Includes water from;

• Springs,
• Wells
• Borehole

Rain water:

This is water tapped in various ways such as;

• Rooftops
• Rock surface, when it is raining and stored in various ways.

Collection and Storage of Water

Dams:

• These are structures constructed across rivers and channel
• They collect and store water for use during the dry season.

Weirs:

• These are structures constructed across rivers to raise the water level for easy pump
• Unlike in the dams water flows over the barrier created across the river.

Water Tanks:

• These are structures made of concrete, stone, metal sheets and plastics.
• They store water from rain or that which has been pumped from other sources.
• Tanks should be covered to prevent contamination from dust.

Pumps and Pumping of Water

• Pumping is the lifting of water from one point to another by use of mechanical force.
• Water is pumped from the various sources and then conveyed to where it is required for use or storage.

       Types of Water Pumps

Used to lift water from its source.

• Centrifugal pumps
• Piston or reciprocating pumps
• Semi-rotary pumps and
• Hydram

Conveyance of Water

• This is the process of moving water from one point, usually the source or point of storage to where it will be used or stored.

Piping;

This is where water is moved through pipes.

The common types of pipes include:

• Metal pipes
• Plastic pipes
• Hose pipes

Use of Containers:

• In this case water is drawn and put in containers .
• drums, jerry cans, pots, gourds, tanks and buckets .
• Which are carried by animals, bicycles, human beings and vehic

Use of Canals:

• In this case water is conveyed from a high point to a lower one along a gradual slope to avoid soil erosion.
• Water conveyed through this way is mostly used for irrigation and livestock.

Water Treatment

• Raw water contains impurities which may be dissolved, floating or suspended in water.

These impurities are grouped into three categories, namely:

• Physical impurities: these are dissolved impurities detected by colour, taste and smell.
• Chemical impurities: these are dissolved impurities detected by use of chemical analysis.
• Biological impurities: these are microorganisms in water such as bacteria, viruses and algae.

Importance of Treating Water

• To kill disease causing microorganisms such as cholera and typhoid bacteria that thrive in dirty water.
• To remove chemical impurities such as excess fluoride which may be harmful to human beings.
• To remove smells and bad taste.
• To remove sediments of solid particles such as soil, sand and sticks.

Methods of Treating Water

• Aeration: this is the removal of smell and odour from water by fine spraying or bubbling of air.
• Sedimentation: this is where water is put in large containers so that solid particles such as sand, metal and others can settle at the bottom.
• Filtration: this is passing water through fine granular materials to remove solid particles and biological substances.
• Coagulation: addition of chemicals which precipitate impurities and help in softening of hard water.
• Chlorination: Sterilization to destroy disease causing organisms.

Irrigation

• It is the artificial application of water to crops in dry areas or where water is not enough.
• It is one of the methods of land reclamation in case of arid and semi arid areas.

Factors to Consider in Identifying and Assessing the Potential of Land for Irrigation Development

• Topography of the land
• Soil type
• Type of crop to be grown
• Water availability
• Human factors such as skill, capital availability and economic activities.

Types of Irrigation

Surface irrigation:

• This includes flood irrigation and basin irrigation.
• It is used in flat areas.
• The problem with this method is loss of water through seepage.
• It also increases soil salinity.

Sub-surface Irrigation:

• This involves the use of porous pipes or perforated pipes.
• It is used in slopy areas and where water is inadequate.

Overhead or Sprinkler Irrigation:

• It is used in any area which is not steep.

Drip or Trickle Irrigation:

• It is used where water is little and in relatively sloppy and flat areas. 

Drainage

• This is a method of removing excess water or lowering the water table from a marshy water-logged land.
• It is also a method of land reclamation.

      Importance of Drainage as a Method of Land Reclamation

• To increase soil aeration.
• To raise soil temperature.
• To increase microbial activities in the soil.
• To reduce toxic substances from the soil.
• To increase soil volume for exploitation by plant roots.

     Methods of Drainage

• Use of open ditches.
• Use of underground drain pipes.
• French drains.
• Cambered beds.
• Pumping out water from the soil.
• Planting tree species which absorb a lot of water for example eucalyptus.

Water Pollution

• This is the process by which harmful substances get into the water.
• The harmful substance is referred to as a pollutant.

Agricultural practices which pollute water include:

• Use of inorganic fertilizers.
• Use of pesticides.
• Poor cultivation practices such as over cultivation, cultivating along the river banks.
• Overgrazing which leads to erosion of soil thus causing siltation in water sources.

Methods of Preventing Water Pollution

• Soil conservation measures which minimize soil losses through erosion
• Fencing off the water sour
• Adopting organic farming practices for example controlling pests and weed using non-chemical techniques.
• Planting grass along river banks to minimize siltation in rivers.
• Proper disposal of empty chemical containers.