By Leah Munala
Water is an important natural resource in sustaining life for plants and animals. However ,its inequitable distribution has led to the exploitation of alternative sources. Harvested water plays a crucial role in both agricultural production and domestic use.
Most farming communities depend on rain-fed agriculture, which is sometimes characterized by acute dry weather periods. Water is scarce, and thus, there is a need for its conservation and sustainable use.
Harvested water plays a crucial role in both agricultural production and domestic use. Most farming communities depend on rain-fed agriculture, which is sometimes characterized by acute dry weather periods.
Water conservation can be done through the application of sustainable land management practices that include soil and water conservation, agroforestry, and conservation agriculture.
Water harvesting technologies play a significant role in counteracting unfavorable weather conditions and climate change by ensuring that the little water available is utilized well and stored for future use. The most common water harvesting techniques are collecting rainwater from the rooftops and surface run-off.
Water harvesting from rooftops – Rainwater is collected from the roof of the house or building as a catchment using a gutter. This requires a farmer to have a water tank or storage container or divert the water into an underground tank or a recharge well.
Collecting surface runoff – Surface runoff is the rainwater that moves or flows on the ground that is saturated or a hard area that doesn’t allow the water to pass into the soil. Surface runoff can cause soil erosion and flooding, leading to water pollution and damaging water drinking sources. Controlling surface runoff using soil and water conservation structures is one of the water harvesting techniques a farmer can apply on the farm to improve productivity sustainably. Directing this water into storage structures such as farm ponds, soil bands, and retention ditches makes it available for plant use for a longer period. This technology also ensures that the soil is conserved thus improving the value of the land.
Water conservation can be done through the application of sustainable land management practices
This can be done through establishing physical structures like terraces, agroforestry systems, conservation agriculture, and mulching, which control soil erosion, prevent moisture loss from the soil, and improve soil fertility, resulting in improved productivity.
Terracing in water harvesting
A terrace is a physical soil and water conservation structure used to reduce the speed of surface runoff and collect water so that it percolates into the soil, preventing soil erosion
Types of terraces
- Cut-off drains – refers to terraces dug across a slope to capture surface runoff and divert the water into a dam, stream or river. They are usually graded, and a
farmer requires technical support to set up the cut-off drains. - Retention ditch – established on the farm to collect surface runoff water so that it seeps into the soil. They can be used as an alternative to cut-off drains where there is no waterway to discharge the surface runoff . The retention ditches are usually separated using tied ridges and are not continuous. The first terrace is usually made at the start of the farm to capture the water from the compounds or roads.
- Converse terrace (fanya Juu) – refers to the terrace where the excavated soil is heaped on the upper side to form an embankment. With time the converse terrace forms bench terraces that help in soil and water conservation.
After establishing the terraces, plant vegetation on the soil heap to strengthen the water harvesting structure. These include Napier grass, brachiaria, vetiver, and agroforestry trees.
Water harvesting technologies play a significant role in counteracting unfavorable weather conditions and climate change by ensuring that available water is utilized well and stored for future use. The most common water harvesting techniques are collecting rainwater from
rooftops and surface run-off.
Advantages of terracing in water harvesting:
- Controls soil erosion— surface runoff water carries topsoil; establishing terraces would capture soil sediments and nutrients, improving soil fertility within the farm and thus productivity.
- Reduced pollution of water sources -surface runoff carries fertilizer and other chemicals from the farm to water bodies reducing its quality for other domestic uses. Harvesting surface runoff will ensure these chemicals don’t pollute the water bodies.
- Reduced flooding – water harvested on the farm reduces fl ood occurrence in the lowlands.
- Reduced cost of production – water harvested is used in watering crops thus reducing irrigation costs. The vegetative cover planted along the terraces serves as feed for livestock.
Disadvantages of terracing as a water harvesting technique
- Requires technical skills in laying out the water conservation structures.
- Unreliable rainfall –affects the quantity of water harvested, which might affect planned farming activities.