Micro-hydro Power (MHP) Projects - Mitigation and Intervention Techniques - Water Harvesting

Overview

► Back to the overview "Mitigation and Intervention Techniques Related to Micro-hydro Power (MHP) Projects"

Water Harvesting

Hand-dug Wells

Objectives: Hand dug wells are used to irrigate small plots or to supply drinking water for human and livestock.

Low Cost Water Lifting

Objectives: They are instrumental in increasing the size of plot and provide the right amount of water to crops at the the right time. The treadle pump, relative to the traditional rope and bucket system will increase irrigated surface areas and reduce irrigation labour time relative to the original irrigated surface area. Thus, resulting in increased production.

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Low Cost Micro-ponds

Objectives: Supplementary irrigation to high value crops (horticulture, fruit trees, etc.). Water for livestock for a few months. Micro ponds allow to use surface runoff from small catchment areas within and between homesteads (foot paths, small grazing land areas, rocky areas, etc.). Can also collect water from feeder roads, graded bunds, spillways, etc.). Water collected can be used during the rainy season as supplementary irrigation (during dry spells) or after (1-2 months max) for additional support to horticulture crops, fruit trees, compost, small livestock, beekeeping, etc.

Underground Cisterns

Objectives: Supplementary irrigation to high value crops (horticulture, fruit rees, small livestock, etc.). Water for livestock for a few months. Water for raising seedlings in dry seasons. Microponds allow to use surface runoff from small catchment areas within and between homesteads (foot paths, small grazing land areas, rocky areas, etc.). Water collected can be used during the rainy season as supplementary irrigation (during dry spells) or after (1-2 months max) for additional support to horticulture crops, fruit trees, compost, small livestock, beekeeping, etc.).

Percolation Pit

Objectives: A percolation pit is a structure, constructed on any marginal land with pervious soil, with the following objectives: Recharge the ground water Enhance biomass production through improved water availability in the soil profile. Reduce runoff and subsequently erosion and land degradation.

Percolation Pond

Objectives: A percolation pond is a structure, constructed on any marginal land with pervious soil, with the following objectives: Recharge the ground water Enhance biomass production through improved water availability in the soil profile. Reduce runoff and subsequently erosion and land degradation.

Farm Pond Construction

Objectives: To store surface water for use during dry seasons for the purpose of domestic use, human consumption, irrigation or for fish production.

Spring Development

Objectives: Proper spring development helps protect the water supply from contamination. The objective of spring development is to collect the flowing underground water to protect it from surface contamination, store it and avail for use.

Family Drip Irrigation System

Objectives: Increased frequency and uniformity of water application plus reduced competition from weeds results in improved plant growth and yield increases of 30 to 50 percent. The system is instrumental in increasing the size of plot and provide the right amount of water to crops at the the right time. Thus, resulting in increased production.

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Roof Water Harvesting System

Objectives: Roof water harvesting is a system for the collection of rainwater for domestic water supply. Roof catchments are used to collect water for individual household use, in schools and other institutions. Gutters and ground storage tanks are required to collect rainwater from roofs; Roof catchements are made of GI sheet and grass tatched materials; It also provides water for livestock, agricultural and fish-farming use.

Farm Dam Construction

Objectives: Storage farm dams are mainly to store surface runoff water and to use it when required for various uses such as for human and animal consumption, small scale or supplementary irrigation, fish production.

River-bed or Permeable Rack Dams

Objectives: River bed dams are a floodwater farming techniques where runoff waters are spread in valley bottoms of seasonal riverbeds, large gullies or natural water courses for improved crop and forage producdtion using a long, low structure, made from loose stone (occasionally some gabion baskets may be used). Developing gullies are healed at the same time. Occasionally it is required to raise the riverbed in order to guide spate floods into irrigation canals of spate irrigation schemes, or to accumulate river sediments for riverbed cultivation. In such a case, very strong dams are required that can resist powerful spate floods. It is a relatively low cost structure especially designed to resist heavy flooding. The structures are typically long, low dam walls across valleys. The large amount of work involved means that the technique is labor intensive and needs group approach.

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Small Stone Bunds with Run-on and Run-off Areas

Objectives: The main objective is to considerably increase the biomass production of forage grass and legumes pastures and fodder crops and/or allow the introduction of species having higher water requirements in abandoned, marginal and eroded dry areas. The principle of the system and its application is the same as for runoff/runon systems suggested for the cultivated areas. Rainfall multiplier systems for grazing land can also rehabilitate fertility (decay of grass and increased moisture). In this respect, a few years pasture improvement and soil fertility restoration may allow the area to be cropped again. The main difference between this measure and the one described for the cultivated land is that instead of food crops fodder plants are grown. The system is less demanding in terms of size of structures and management of the plots as fodder species require less water than food crops.

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Narrow Stone Lines Along the Contour

Objectives: Stone lines are semi-permeable or permeable structures, intended to capture some moisture and thus allow the growth of spontaneous grass. By slowing down runoff they also decrease erosion, although not completely. This is a soil and moisture conservation measure suitable for rangelands and degraded grazing lands in dry areas. The measure is less labour intensive and material demanding than small stone faced soil bunds but less efficient. The principle is rainfall multiplier system but the measure is applicable only if stones are available.

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Stone Faced/Soil or Stone Bunds with Run-off/ Run-on Areas

Objectives: This is a rainfall multiplier system for reclaiming and rehabilitating marginal areas with low productivity, shallow soils, often affected by surface crusts and low water infiltration rates, with slope ranging between 1 to 5%. Both runoff and runon areas are included within the bunds. The runoff area is intended to serve as a micro catchment to supply additional water into a runon area (cultivated area) to increase production levels in one portion of the total area or to introduce crops with higher water requirements that otherwise would not grow without additional moisture.

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Conservation Bench Terraces (s) (CBT(s))

Objectives: CBTs are constructed on steep slopes to combine soil and water conservation with water harvesting practices. They control erosion and retain moisture and are suitable for food/ tree crops and are effective in controlling runoff and erosion. They are also water harvesting structures, the riser acts as a catchment. Common in most parts of Ethiopia, (e.g Konso) generally in dry areas. Benching action eases cultivation operation by oxen, however, more appropriate to use.

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Tie Ridge (s)

Objectives: Tie ridges are small rectangular series of basins formed withing the furrow of cultivated fields mainly to increase surface storage and to allow more time for rainfall to infiltrate the soil. Making tied ridges manually is time and labor consuming.

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The Zai and Planting Pit System

Objectives: Zai pits are systems of small pits dug along approximate contours allows the cultivation of crops on degraded lands. The zaï pits restore degraded lands (crusted, hard, compacted and poorly structured soils), thus increasing the land available for cultivation. It is a simple technique that, amongst others, landless or oxless can practice because it requires only manual labour.

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Large Half Moons

Objectives: The measure is a rainfall multiplier system that allow cultivation of crops in low rainfall areas. It is applied in areas with sandy and sandy loamy soils affected by low fertility levels and thin surface crusts that inhibit infiltration and increase runoff. Large half moons are suitable structures to enable cultivation of drought resistant crops in areas with very low rainfall. They intercept all runoff and stop erosion. It is also a measure suitable for rangelands and degraded grazing lands in dry areas (forage crops).

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Division Weir Design and Construction

Objectives: To divert stream flow for use during dry seasons for the purpose of small scale irrigation and for any other supplementary irrigation.

Further Information

• Hydro Portal on energypedia
• agriwaterpedia.info - Water Harvesting
• Using Hydro Power Plants for Flood Prevention
  

References

DESTA, L. et al. (2005): Part 1: Community Based Participatory Watershed Development: A Guideline. Addis Ababa: Ministry of Agriculture and Rural Development.