Surface irrigation: Types, advantages, and disadvantages

Water is a vital component of plant growth. Several plants need more water to thrive, while others require less. However, they need a certain water ratio that promotes optimal growth, not just an equal quantity. The mechanismsthan basin or border irrigation, furrow irrigation involved in irrigation make it simple to provide enough water for your plants. One form of irrigation procedure is surface irrigation.

This article will cover all there is to know about surface irrigation, including its several types, how it operates, and any other relevant information.

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known about basin irrigation

Surface irrigation: What is it?

Water delivery to crops using gravity-driven, overland flowing water is called surface irrigation. In most cases, surface irrigation is only employed in areas where the ground has been graded to ensure that there are regular slopes. Flood irrigation is a common misnomer when referring to the surface irrigation technique due to its unregulated water distribution. However, if done properly, surface irrigation might be the most effective method for watering your crops.

Surface irrigation: How does the surface irrigation system function?

Surface irrigation is a simple and all-natural method of water management. Just four steps are required to complete the procedure. 

1. The fields get water from the top down; the water flows down the length of the fields in the first step.
2. The duration of the water supply will determine how long the second or advanced step will last. Once again, water is delivered to the highest point of the fields, slowly seeping down into the pond below.
3. The third, or storage step, covers the time between the progress phase’s conclusion and the shut-off phase’s beginning. During the depletion phase, the whole field’s length is immersed for a brief time.
4. The last step is known as the recession phase. It refers to the moment when the waterfront is progressing toward the downstream portion of the field.

Surface irrigation: Types

This type of irrigation method is the one that is utilised the most often in countries all over the globe. There are 3 types to choose from when it comes to surface irrigation.

• Basin irrigation 

Basin irrigation is a method that has been used for several years in confined spaces that have flat terrain. The basin system is made up of flat, diked regions that are fed by uncontrolled water runoff. Small basins are used for orchard crops, whereas larger basins may hold hundreds of square feet of soil. Some big basins include corrugated surfaces on the soil to help with water distribution.

The embankments must protect the basin and be strong and regularly maintained to avoid a break. However, embankments should always be built with spill structures in case of unexpectedly high rainfall or an error in the timing of irrigation shutoff. Basin irrigation is suitable for crops that can survive flooding because of the basin’s near-zero surface elevation and confined borders.

• Border irrigation 

Border irrigation is distinct from basin irrigation in three key respects: its rectangular form, its sloping surface, and the absence of a diked end (free drainage). Almost all crops can be irrigated effectively using borders, except those that need standing water (e.g. rice). The inflow rate must be calculated precisely; it must be high enough to permit waterfront progress without being so high as to destroy the rich topsoil from the field.

• Furrow irrigation

With furrow irrigation, furrows are dug into the soil’s surface to create channels that guide the water flow and keep the area from being flooded. These ruts are channels for water, which flows down their length and seeps into the ground through the crevices in their walls. Every furrow has its own water source, whether it is a hand-dug check, a gated pipe, or a siphon tube.

Though it allows for more precise management of water resources than basin or border irrigation, furrow irrigation has a few drawbacks. One drawback is the potential for salt accumulation on beds in areas where water is insufficient. Second, more surface runoff is produced in furrow systems. Lastly, they are more difficult to work with because of the added effort required to move agricultural equipment amid the increased number of furrows.

• Spate (flood) irrigation

In spate irrigation, the term spate refers to flood or inundation. This type of irrigation uses seasonal floods of rivers, streams, ponds, and lakes. This is a traditional irrigation method used in arid and semi-arid climates. In spate irrigation system, water is diverted from normally dry riverbeds when the river is in spate.

Surface irrigation: Advantages

At the farm and project levels, surface irrigation provides several significant advantages, including the following.

• Given its prevalence, local irrigators are likely to have some familiarity with its operation and upkeep.
• Because the depths needed to replenish the root zone seem to be simpler to apply with surface systems, they are generally more desirable to agriculturalists who understand the consequences of water scarcity on crop yields.
• Surface irrigation has the additional benefit of being easily implemented with little outlay of money on the part of the farmer. The structures for regulation and control are simple, long-lasting, and may be built using common and cheap building materials such as wood, concrete, brick, etc. Canals are lined with PCC, RCC, and bricks for this reason.
• The key structural parts are also situated near the field margins, making operation and maintenance much simpler.
• Surface irrigation systems rely only on gravity for their energy needs. In today’s low-energy economy, this is a major boon.
• Characteristics like climate and water quality have less of an impact on surface irrigation.
• To a lesser extent than with these pressurised systems, salinity is less of an issue with surface irrigation.

Surface irrigation: Disadvantages 

Surface irrigation does have several benefits, but there are also several drawbacks, which will be described in more detail below.

• Due to the soil’s extremely variable spatial and temporal features, it will be difficult to find an optimal method for distributing the water evenly throughout the area. This presents an engineering challenge since estimates of at least two of the key control parameters, outflow and time taken for application, must be established not only during field layout but also by the irrigator before initiating any surface irrigation cycle. 
• Surface irrigation is often inefficient compared to sprinkler and trickle irrigation systems. Inadequate drainage may lead to flash flooding and soil salinity for many of these areas since they are located on lower ground with heavier soils. Fields should be appropriately graded if they are to be used as a distribution and transportation facility so that the surface can be easily transported and distributed. Since it may be expensive to level ground, surface irrigation is often reserved for flat or gently sloping land areas.
• Most surface systems need a lot of manual labour. Skill is not an issue here. However, rigorous attention to detail in implementing the irrigator’s prescribed irrigation procedures is essential for achieving optimal efficiency. For bigger fields, keeping track of the water’s movement across the land and knowing when to stop the intake is essential. Poor efficiency results from poor decision-making or design.
• The inability to administer short, frequent irrigations at the beginning and end of the growing season to various crops is a sometimes significant drawback of surface irrigation technologies. In heavy calcareous soils, for instance, crust development occurs after the initial watering and before crop germination; mild irrigation to dissolve the crust would significantly increase yields. This may be impossible or impracticable with surface irrigation systems since the water may not be easily accessible to the field, or the required watering depths may be too considerable.

Designing a surface irrigation system for your land

In any irrigation system, a particular size of stream is available for irrigating the land with a particular topography and soil qualities. These must be matched so that the required amount of water is applied in the field. The data needed for the design are broadly classified into the following categories:

• Soil characteristics, including infiltration rates, field capacity, wilting point, bulk density, salt content, and effects of surface flooding like crusting and cracking.
• Crop data, which includes types of crops proposed to be raised in the field, agronomical requirements like ridging etc., rooting habits, and allowable soil water deficits at different stages of growth and relative sensitivity to inundation.
• Information on water such as the available stream size, quality of the irrigation water, expected amount and distribution of rainfall, etc.
• Slope of the area to be irrigated, and size and shape of the field.

According to the design principles, the surface irrigation system must be able to apply an equal depth of water across the field without leading to erosion. After the water is allowed to enter the plot, it will move towards the end of the filed. Recession of water begins from the starting of the plot after water flow is shut. Most of the time it becomes essential to stop the inflow of water when the water front reaches a specific length of the plot, so that the irrigation of the remaining length is done with the water already brought in the field.

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