Difference between revisions of "Mitigation and Intervention Techniques Related to Micro-hydro Power (MHP) Projects"
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− | === '''<span style="color: rgb(255, 255, 255) | + | === '''<span style="color: rgb(255,255,255)">BIOPHYSICAL MEASURES<ref>DESTA, L. ET AL. (2005): Part 1: Community Based Participatory Watershed Development: A Guideline. Addis Ababa: Ministry of Agriculture and Rural Development.</ref></span>''' === |
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*<u>Objectives</u>: A stone checkdam is a structure across the bottom of a gully or a small stream, which '''reduces the velocity of runoff''' and '''prevents the deepening and widening of the gully'''. Sediments accumulated behind a checkdam could be planted with crops or trees/shrubs grass and thus provide additional income to the farmer.<br> | *<u>Objectives</u>: A stone checkdam is a structure across the bottom of a gully or a small stream, which '''reduces the velocity of runoff''' and '''prevents the deepening and widening of the gully'''. Sediments accumulated behind a checkdam could be planted with crops or trees/shrubs grass and thus provide additional income to the farmer.<br> | ||
− | [[Image:Gully Control.jpg|left|315x234px|Gully Control.jpg]]<br> | + | [[Image:Gully Control.jpg|left|315x234px|Gully Control.jpg]]<br> |
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− | <br> | + | '''Brushwood Checkdams'''<br> |
− | < | + | *<u>Objectives</u>: Brushwood checkdams are vegetative measures constructed with vegetative materials, branches, poles/posts and twigs. Plant species which can easily grow vegetatively through shoot cuttings are ideal for this purpose. The objective of BWs is to '''retain sediments and slowdown runoff''', and enhance the '''revegetation of gully areas'''. They are constructed either in single or double row. Some of the vegetation can be used for fodder. BWs are also ideal to stabilize conservation structures bunds, SS bunds, check dams, bench terraces, road sides, etc. [[Image:BrushwoodCheckdam.png|left|315x221px|BrushwoodCheckdam.png]] |
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'''Gully Reshaping, Filling and Revegetation''' | '''Gully Reshaping, Filling and Revegetation''' | ||
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*<u>Objectives</u>: Reshaping & Filling is an operation meant to '''decrease the gully erosion''' angle of incidence, '''create planting areas and encourage revegetation & stabilization''', usually in small gullies or in other medium sized gullies from which most runoff has been diverted into a stable waterway or drainage line. When these gullies are shaped and smoothed, vegetation can be established over the levelled gullies. Some of these areas can be used for farming purposes. Revegetation of a gully is the plantation of the reshaped gully sides and bottom with multipurpose species so that it reduces runoff and control erosion and make the land productive. Gully revegetation implies reaching a dense vegetation cover over the entire gully surface, i.e. both sides and bottom by planting grasses, legumes and a variety of trees and shrubs. | *<u>Objectives</u>: Reshaping & Filling is an operation meant to '''decrease the gully erosion''' angle of incidence, '''create planting areas and encourage revegetation & stabilization''', usually in small gullies or in other medium sized gullies from which most runoff has been diverted into a stable waterway or drainage line. When these gullies are shaped and smoothed, vegetation can be established over the levelled gullies. Some of these areas can be used for farming purposes. Revegetation of a gully is the plantation of the reshaped gully sides and bottom with multipurpose species so that it reduces runoff and control erosion and make the land productive. Gully revegetation implies reaching a dense vegetation cover over the entire gully surface, i.e. both sides and bottom by planting grasses, legumes and a variety of trees and shrubs. | ||
− | [[Image:GullyReshapingRevegetation.png|left| | + | [[Image:GullyReshapingRevegetation.png|left|321x221px|GullyReshapingRevegetation.png]]<br><br><br> |
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− | '''Sediment Storage and Overflow Earth Dams (SS Dams) for Productive Gully Control'''<br> | + | '''Sediment Storage and Overflow Earth Dams (SS Dams) for Productive Gully Control'''<br> |
*<u>Objectives</u>: SS dams are water harvesting and conservation systems that convert unproductive large and active gullies into productive areas (fertile cultivated or fodder producing areas, mixed plantations, and fruit tree orchards). SS dams are stone-faced earth dams constructed across medium/large size gullies to trap sediments, collect water and divert excess runoff. SS dams accommodate the runoff generated by the catchment located above the gully. The structures are often constructed in series along the gully. It is just like creating a land that does not exist. Contribute significantly '''to protect cultivated lands, arrest gully expansion and recharge water tables'''. Huge potential in Ethiopia - can provide tens of thousand Km of gullies to poor households (small land holders and landless). | *<u>Objectives</u>: SS dams are water harvesting and conservation systems that convert unproductive large and active gullies into productive areas (fertile cultivated or fodder producing areas, mixed plantations, and fruit tree orchards). SS dams are stone-faced earth dams constructed across medium/large size gullies to trap sediments, collect water and divert excess runoff. SS dams accommodate the runoff generated by the catchment located above the gully. The structures are often constructed in series along the gully. It is just like creating a land that does not exist. Contribute significantly '''to protect cultivated lands, arrest gully expansion and recharge water tables'''. Huge potential in Ethiopia - can provide tens of thousand Km of gullies to poor households (small land holders and landless). | ||
− | <br> '''Sediment Storage and Overflow Soil Bunds (SS Bunds)''' | + | <br>'''Sediment Storage and Overflow Soil Bunds (SS Bunds)''' |
*<u>Objectives</u>: SS bunds are large and strongly built soil embankments, constructed across gullies, often in series. As for SS dams, their purpose is '''to create a new field for cultivation by allowing and helping the sedimentation (filling) of the space behind each bund'''. After rains, the new fields fill up and retain enough soil and moisture to grow crops. The excess runoff move to the next structure downstream through a spillway. | *<u>Objectives</u>: SS bunds are large and strongly built soil embankments, constructed across gullies, often in series. As for SS dams, their purpose is '''to create a new field for cultivation by allowing and helping the sedimentation (filling) of the space behind each bund'''. After rains, the new fields fill up and retain enough soil and moisture to grow crops. The excess runoff move to the next structure downstream through a spillway. | ||
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[[Image:SedimentStorageOverflowSoilBunds.png|left|315px|SedimentStorageOverflowSoilBunds.png]] | [[Image:SedimentStorageOverflowSoilBunds.png|left|315px|SedimentStorageOverflowSoilBunds.png]] | ||
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− | ==== '''Agro-forestry, Forage Development and Forestry''' | + | ==== '''Agro-forestry, Forage Development and Forestry''' ==== |
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*<u>Objectives</u>: Strip cropping is a cropping practice where strips of two or more crops are alternately established on the contour or, it is a system of establishing more than one crop in alternate strips following a contour pattern for the purpose of erosion control, crop diversification, and decrease the risks associated to the use of single crops only. This cropping system is designed as a defence mechanism '''against soil erosion''' in areas where the cropping system is dominated by row/sparsely growing crops that exposes the ground to erosive forces. For instance, crops like sorghum and maize are susceptible to erosion and need to be grown alternately with soil conserving crops. | *<u>Objectives</u>: Strip cropping is a cropping practice where strips of two or more crops are alternately established on the contour or, it is a system of establishing more than one crop in alternate strips following a contour pattern for the purpose of erosion control, crop diversification, and decrease the risks associated to the use of single crops only. This cropping system is designed as a defence mechanism '''against soil erosion''' in areas where the cropping system is dominated by row/sparsely growing crops that exposes the ground to erosive forces. For instance, crops like sorghum and maize are susceptible to erosion and need to be grown alternately with soil conserving crops. | ||
− | [[Image:AreaClosure.png| | + | [[Image:AreaClosure.png|349x183px|AreaClosure.png]]<br><br><br> |
'''Microbasins (MBs)''' | '''Microbasins (MBs)''' | ||
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*<u>Objectives</u>: MBs are small circular & stone faced (occasionally sodded) structures for tree planting. Are suitable for medium and slightly low rainfall areas, stony areas and shallow soils. Based upon experience they are not very effective in low rainfall areas (where trenches, eyebrows, etc. are preferred). | *<u>Objectives</u>: MBs are small circular & stone faced (occasionally sodded) structures for tree planting. Are suitable for medium and slightly low rainfall areas, stony areas and shallow soils. Based upon experience they are not very effective in low rainfall areas (where trenches, eyebrows, etc. are preferred). | ||
− | [[Image:MicroBasin.png|315px|MicroBasin.png]]<br> <br>'''Eyebrow Basins (EBs)''' | + | [[Image:MicroBasin.png|315px|MicroBasin.png]]<br><br>'''Eyebrow Basins (EBs)''' |
*<u>Objectives</u>: EB are larger circular and stone faced (occasionally sodded) structures for tree and other species planting. Based upon experience they are effective in low rainfall areas to grow trees and harvest moisture. Can be constructed in slopes above 50% for spot planting. '''Controls runoff and contribute to recharge of water tables'''. | *<u>Objectives</u>: EB are larger circular and stone faced (occasionally sodded) structures for tree and other species planting. Based upon experience they are effective in low rainfall areas to grow trees and harvest moisture. Can be constructed in slopes above 50% for spot planting. '''Controls runoff and contribute to recharge of water tables'''. | ||
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*<u>Objectives</u>: IPs are square shaped water collection pits constructed along the contours with a plantation pit in front of the main water storage pit - main purpose similar as micro-trenches. IP '''support the growth of trees and fodder shrubs''', and can be used for cash crops like coffee. They are effective in medium and low-medium rainfall areas (above 600-700 mm). | *<u>Objectives</u>: IPs are square shaped water collection pits constructed along the contours with a plantation pit in front of the main water storage pit - main purpose similar as micro-trenches. IP '''support the growth of trees and fodder shrubs''', and can be used for cash crops like coffee. They are effective in medium and low-medium rainfall areas (above 600-700 mm). | ||
− | <br>'''Multistorey Gardening'''<br> | + | <br>'''Multistorey Gardening'''<br> |
*<u>Objectives</u>: Multi-storey gardening is a way of planting a mixture of crops, shrubs and trees of different heights and different uses: food crops, cash crops, fruit trees, woody perennials, and forage plants. It '''makes the land more productive and improves soil fertility, reduces temperature, provides shade, and increase family income''', particularly during a period of drought.Fields close or within homesteads can be converted into diversified productive units (decreasing risk factors, increased income, etc.). Such systems have higher resistance to pests and insects. A broad network of such homesteads can extend into open fields and constitute large erosion-protected zones or a “web” of green fences and mutually supporting units. | *<u>Objectives</u>: Multi-storey gardening is a way of planting a mixture of crops, shrubs and trees of different heights and different uses: food crops, cash crops, fruit trees, woody perennials, and forage plants. It '''makes the land more productive and improves soil fertility, reduces temperature, provides shade, and increase family income''', particularly during a period of drought.Fields close or within homesteads can be converted into diversified productive units (decreasing risk factors, increased income, etc.). Such systems have higher resistance to pests and insects. A broad network of such homesteads can extend into open fields and constitute large erosion-protected zones or a “web” of green fences and mutually supporting units. | ||
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[[Image:MultiStoreyGardening.png|342x266px|MultiStoreyGardening.png]] | [[Image:MultiStoreyGardening.png|342x266px|MultiStoreyGardening.png]] | ||
− | <br> '''Seed Collection''' | + | <br>'''Seed Collection''' |
*<u>Objectives</u>: Seed collection is divided into two:(1) Seed collection of tree species: mostly for indigenous trees to grow in nurseries for specific and multipurpose uses. (2) Legume shrubs and grass seeds: mainly legume shrubs seeds and grass/plant species that can be used for '''stabilisation, homestead plantations, grazing lands improvement, support to nurseries, fencing, gully control'''. This activity is especially valuable for grass seeds collected outside the nursery areas and seed multiplication centers, particularly native grasses of particular value for their palatability and adaptation to local conditions. The collection of local seeds is an effective way to protect valuable planting materials from extinction and to replenish depleted areas with materials collected from other areas. | *<u>Objectives</u>: Seed collection is divided into two:(1) Seed collection of tree species: mostly for indigenous trees to grow in nurseries for specific and multipurpose uses. (2) Legume shrubs and grass seeds: mainly legume shrubs seeds and grass/plant species that can be used for '''stabilisation, homestead plantations, grazing lands improvement, support to nurseries, fencing, gully control'''. This activity is especially valuable for grass seeds collected outside the nursery areas and seed multiplication centers, particularly native grasses of particular value for their palatability and adaptation to local conditions. The collection of local seeds is an effective way to protect valuable planting materials from extinction and to replenish depleted areas with materials collected from other areas. | ||
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− | ==== '''Soil Fertility Management and Biological Soil Conservation''' | + | ==== '''Soil Fertility Management and Biological Soil Conservation''' ==== |
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− | '''Compost Making'''<br> | + | '''Compost Making'''<br> |
*<u>Objectives</u>: To promote compost making at household level for cost-effective '''soil fertility improvement'''<br>and to support local level compost entrepreneurship linked to natural resources management activities at watershed level. CM will improve soil fertility, '''increase water storage within the soil profile and reduce surface runoff, thus reduce soil erosion'''. It is one of the best “hidden” water harvesting methods available (compost absorbs water 4-7 times its own weight). CM can be undertaken at very large scale and linked to area closure management and the upgrading of terraces into “cash crop production belts”. CM can become a business: groups of households (landless, etc.) can decide to become compost makers and provide “fertilization” services to other farmers.<br> | *<u>Objectives</u>: To promote compost making at household level for cost-effective '''soil fertility improvement'''<br>and to support local level compost entrepreneurship linked to natural resources management activities at watershed level. CM will improve soil fertility, '''increase water storage within the soil profile and reduce surface runoff, thus reduce soil erosion'''. It is one of the best “hidden” water harvesting methods available (compost absorbs water 4-7 times its own weight). CM can be undertaken at very large scale and linked to area closure management and the upgrading of terraces into “cash crop production belts”. CM can become a business: groups of households (landless, etc.) can decide to become compost makers and provide “fertilization” services to other farmers.<br> | ||
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'''Fertilization and Manuring''' | '''Fertilization and Manuring''' | ||
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*<u>Objectives</u>: Live check-dams are established by planting/seeding or plugging of cuttings in gully bottoms to replace or reinforce physical check-dams. The main objective of the establishment of live check-dams is to reduce the cost of establishing physical check-dams. Live check-dams can be applied by individual farmers and does not need the organization of a large group of people to undertake physical structures. | *<u>Objectives</u>: Live check-dams are established by planting/seeding or plugging of cuttings in gully bottoms to replace or reinforce physical check-dams. The main objective of the establishment of live check-dams is to reduce the cost of establishing physical check-dams. Live check-dams can be applied by individual farmers and does not need the organization of a large group of people to undertake physical structures. | ||
− | [[Image:LiveCheckdams.png| | + | [[Image:LiveCheckdams.png|530x231px|LiveCheckdams.png]] |
<br>'''Mulching and Crop Residues Management''' | <br>'''Mulching and Crop Residues Management''' | ||
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*<u>Objectives</u>: Mulching is the covering of the soil with crop residues such as straws, maize/sorghum<br>stalks or standing stubble. The cover '''protects the soil from raindrops, drastically reduces splash erosion and velocity of runoff'''. It then '''minimises erosion, increases soil infiltration and permeability, prevents the formation of hard crusts and contribute to improve fertility'''. The second major advantage of mulching/crop residue maintenance, is its potential for sustaining productivity. Mulching, in addition to its positive effects on soil structure also helps in reducing evaporation and maintaining soil moisture. The improved soil structure also will have an effect on '''moisture retention and consequently higher water budgets''' for the growing crop. | *<u>Objectives</u>: Mulching is the covering of the soil with crop residues such as straws, maize/sorghum<br>stalks or standing stubble. The cover '''protects the soil from raindrops, drastically reduces splash erosion and velocity of runoff'''. It then '''minimises erosion, increases soil infiltration and permeability, prevents the formation of hard crusts and contribute to improve fertility'''. The second major advantage of mulching/crop residue maintenance, is its potential for sustaining productivity. Mulching, in addition to its positive effects on soil structure also helps in reducing evaporation and maintaining soil moisture. The improved soil structure also will have an effect on '''moisture retention and consequently higher water budgets''' for the growing crop. | ||
− | [[Image:Mulching.png| | + | [[Image:Mulching.png|530px|Mulching.png]] |
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'''Grass Strips along the Contours''' | '''Grass Strips along the Contours''' | ||
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*<u>Objectives</u>: Grass strips are vegetative barriers made out of grass planted in narrow strips of 0.5 to 1.5 m width laid out along the contour. Grass strips '''control erosion''' rather effectively in gentle slopes but above 5-8% slope their effect decreases. While contributing to protect soils against erosion they also provide valuable biomass meant to increase animal feed or used for different purposes (eg. roofing, etc.). Grass strips cause less interference than other measures as they can easily be crossed by oxen and plough. Moreover, grass strips take out little amount of arable land. Cost of construction is much lower than physical structures. | *<u>Objectives</u>: Grass strips are vegetative barriers made out of grass planted in narrow strips of 0.5 to 1.5 m width laid out along the contour. Grass strips '''control erosion''' rather effectively in gentle slopes but above 5-8% slope their effect decreases. While contributing to protect soils against erosion they also provide valuable biomass meant to increase animal feed or used for different purposes (eg. roofing, etc.). Grass strips cause less interference than other measures as they can easily be crossed by oxen and plough. Moreover, grass strips take out little amount of arable land. Cost of construction is much lower than physical structures. | ||
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<br>'''Stabilization of physical Structures and Farm Boundaries''' | <br>'''Stabilization of physical Structures and Farm Boundaries''' | ||
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*<u>Objectives</u>: Ley cropping is a cropping system in which legume based pastures are rotated with purely<br>grown crops. Legume based pastures are grown on fallow lands for a few years to improve fertility of the soil and thus the yields of subsequent crops (mainly cereals). The establishment of dense, productive forage crops during the fallow period (1-3 years) provides a thick ground cover, supply forage of good quality after the rainy season, '''prevent soil erosion, restore soil fertility quicker than bare (and overgrazed) fallow, increase the water holding capacity of the soil and have a beneficial effect on future crop yields'''. | *<u>Objectives</u>: Ley cropping is a cropping system in which legume based pastures are rotated with purely<br>grown crops. Legume based pastures are grown on fallow lands for a few years to improve fertility of the soil and thus the yields of subsequent crops (mainly cereals). The establishment of dense, productive forage crops during the fallow period (1-3 years) provides a thick ground cover, supply forage of good quality after the rainy season, '''prevent soil erosion, restore soil fertility quicker than bare (and overgrazed) fallow, increase the water holding capacity of the soil and have a beneficial effect on future crop yields'''. | ||
− | <br>'''Integration of Food/Feed Legumes into Cereal Cropping Systems'''<br> | + | <br>'''Integration of Food/Feed Legumes into Cereal Cropping Systems'''<br> |
*<u>Objectives</u>: <br> | *<u>Objectives</u>: <br> | ||
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#Better '''control of soil erosion''' realised. | #Better '''control of soil erosion''' realised. | ||
− | <br>'''Intercropping '''<br> | + | <br>'''Intercropping '''<br> |
*<u>Objectives</u>: Intercropping is a practice of growing two or more crops along the contour simultaneously in the same plot in a fixed pattern in one season. The aim of intercropping is to '''increase crop production and provide protection to the soil against erosive forces'''. Different planting times and different length of growing periods spreads the labour requirement of planting and harvesting, but also allows midseason change of plan according to the rain in the early part of the season. The various leaf arrangements of different plants allow light to be better intercepted over time. The contrasting patterns of root growth, which utilize different soil layers, optimize the use of available soil moisture and nutrients. Mixed stands protect the soil surface more effectively than pure stands. Overall output per unit area can be much greater from intercrops than single crops and chances of total crop losses are lower than in pure stands. | *<u>Objectives</u>: Intercropping is a practice of growing two or more crops along the contour simultaneously in the same plot in a fixed pattern in one season. The aim of intercropping is to '''increase crop production and provide protection to the soil against erosive forces'''. Different planting times and different length of growing periods spreads the labour requirement of planting and harvesting, but also allows midseason change of plan according to the rain in the early part of the season. The various leaf arrangements of different plants allow light to be better intercepted over time. The contrasting patterns of root growth, which utilize different soil layers, optimize the use of available soil moisture and nutrients. Mixed stands protect the soil surface more effectively than pure stands. Overall output per unit area can be much greater from intercrops than single crops and chances of total crop losses are lower than in pure stands. | ||
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[[Image:Stripcropping.png|315px|Stripcropping.png]] | [[Image:Stripcropping.png|315px|Stripcropping.png]] | ||
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− | ==== Flood Control and Improved Drainage | + | ==== Flood Control and Improved Drainage ==== |
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*<u>Objectives</u>: A waterway is a natural or artificial drainage channel constructed along the steepest<br>slope or in a valley to receive/accommodate runoff from cut-off drains and graded terraces/bunds. The waterway '''carries the run-off to rivers, resevoirs or gullies safely without creating erosion'''. A vegetative waterway can be constructed in areas without stones. The main advantage is that waterways can be constructed for both very small and large size catchments, thus accomodating individual or communal needs for drainage and evacuation/use of excess run-off. Paved waterways are suitable in steeper terrains and areas with large amount of stones. | *<u>Objectives</u>: A waterway is a natural or artificial drainage channel constructed along the steepest<br>slope or in a valley to receive/accommodate runoff from cut-off drains and graded terraces/bunds. The waterway '''carries the run-off to rivers, resevoirs or gullies safely without creating erosion'''. A vegetative waterway can be constructed in areas without stones. The main advantage is that waterways can be constructed for both very small and large size catchments, thus accomodating individual or communal needs for drainage and evacuation/use of excess run-off. Paved waterways are suitable in steeper terrains and areas with large amount of stones. | ||
− | [[Image:Waterways.png|570x196px|Waterways.png]]<br> | + | [[Image:Waterways.png|570x196px|Waterways.png]]<br> |
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'''Cut-off Drains''' | '''Cut-off Drains''' | ||
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*<u>Objectives</u>: A cut-off drain is a graded channel constructed to '''intercept and divert the surface runoff from higher ground/slopes and protect downstream cultivated land or village'''. This safely divert the run-off to a waterway, river, gully, etc. In the dry lands, cut-off drains may be used mainly for the following purposes:<br> | *<u>Objectives</u>: A cut-off drain is a graded channel constructed to '''intercept and divert the surface runoff from higher ground/slopes and protect downstream cultivated land or village'''. This safely divert the run-off to a waterway, river, gully, etc. In the dry lands, cut-off drains may be used mainly for the following purposes:<br> | ||
− | #Divert additional water to cultivated plots;<br> | + | #Divert additional water to cultivated plots;<br> |
− | #Divert additional water to SS dams and croped areas inside gullies;<br> | + | #Divert additional water to SS dams and croped areas inside gullies;<br> |
#Divert additional water into reservoirs for irrigation and/or domestic use. | #Divert additional water into reservoirs for irrigation and/or domestic use. | ||
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*<u>Objectives</u>: <br> | *<u>Objectives</u>: <br> | ||
− | #Increased aeration of the soil.<br> | + | #Increased aeration of the soil.<br> |
#Improved soil workability. | #Improved soil workability. | ||
#Earlier sowing date. | #Earlier sowing date. | ||
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[[Image:ImprovedSurfaceDrainage.png|315px|ImprovedSurfaceDrainage.png]] | [[Image:ImprovedSurfaceDrainage.png|315px|ImprovedSurfaceDrainage.png]] | ||
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− | ==== Physical Soil and Water Conservation | + | ==== Physical Soil and Water Conservation ==== |
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*<u>Objectives</u>: The stone bund '''reduces and stops the velocity of runoff and consequently reduces soil erosion and the steady decline in fertility and crop yields'''. They are semi-permeable structures unless sealed with soil in their upper side. They increase the moisture retention capacity of the soil profile and water availability to plants, and increase the efficiency of fertilizer applications if any. Through their water retention effect the stone bunds may allow some crop yield even in drought years. Stone bunds are entry points for application of organic residues or compost, especially in the first 2-3 meters behind the bund where soil is deeper. | *<u>Objectives</u>: The stone bund '''reduces and stops the velocity of runoff and consequently reduces soil erosion and the steady decline in fertility and crop yields'''. They are semi-permeable structures unless sealed with soil in their upper side. They increase the moisture retention capacity of the soil profile and water availability to plants, and increase the efficiency of fertilizer applications if any. Through their water retention effect the stone bunds may allow some crop yield even in drought years. Stone bunds are entry points for application of organic residues or compost, especially in the first 2-3 meters behind the bund where soil is deeper. | ||
− | [[Image:StoneBunds.png|315px|StoneBunds.png]]<br> | + | [[Image:StoneBunds.png|315px|StoneBunds.png]]<br> |
'''<br>Stone Faced Soil Bunds''' | '''<br>Stone Faced Soil Bunds''' | ||
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*<u>Objectives</u>: Undisturbed soil that is permanently protected by vegetative cover improves in the manner that occur in the native ecosystems,including maintenance of porous and soft soil layers through litter accumulation, intense biological activity, movement of soil fauna, and root growth. These functions improve efficient water, heat, and gas transfers within the entire soil profile. The presence of crop residues on the soil surface '''minimizes soil evaporation, and in regions of low rainfall can conserve water and increase crop water use efficiency thus improving crop yields'''. | *<u>Objectives</u>: Undisturbed soil that is permanently protected by vegetative cover improves in the manner that occur in the native ecosystems,including maintenance of porous and soft soil layers through litter accumulation, intense biological activity, movement of soil fauna, and root growth. These functions improve efficient water, heat, and gas transfers within the entire soil profile. The presence of crop residues on the soil surface '''minimizes soil evaporation, and in regions of low rainfall can conserve water and increase crop water use efficiency thus improving crop yields'''. | ||
− | '''<br> Hillside Terraces''' | + | '''<br>Hillside Terraces''' |
*<u>Objectives</u>: Hillside terraces are physical structures constructed along the contours, generally suitable in steep degraded slopes and shallow soils (although common in other type of soils), suitable for tree planting and rather effective in '''controlling runoff and erosion'''. Common in most parts of Ethiopia, generally in dry areas to support area closure plantation and protect downstream fields. | *<u>Objectives</u>: Hillside terraces are physical structures constructed along the contours, generally suitable in steep degraded slopes and shallow soils (although common in other type of soils), suitable for tree planting and rather effective in '''controlling runoff and erosion'''. Common in most parts of Ethiopia, generally in dry areas to support area closure plantation and protect downstream fields. | ||
− | [[Image:HillsideTerraces.png| | + | [[Image:HillsideTerraces.png|348x273px|HillsideTerraces.png]]<br> |
'''<br>Hillside Terrace with Trenches''' | '''<br>Hillside Terrace with Trenches''' | ||
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*<u>Objectives</u>: HTTs is highly labour intensive - combine both effects of hillsides and trenches constructed immediately above the terrace stone riser, generally suitable for steep slopes (up to 50%) and shallowmedium depth soils (although common in other type of soils). Suitable for tree/shrubs planting and very effective in '''controlling runoff and erosion'''. HHTs ensure protection of downstream fields, and play a significant role in replenishing water tables. | *<u>Objectives</u>: HTTs is highly labour intensive - combine both effects of hillsides and trenches constructed immediately above the terrace stone riser, generally suitable for steep slopes (up to 50%) and shallowmedium depth soils (although common in other type of soils). Suitable for tree/shrubs planting and very effective in '''controlling runoff and erosion'''. HHTs ensure protection of downstream fields, and play a significant role in replenishing water tables. | ||
− | [[Image:HillsideTerraces and Trenches.png| | + | [[Image:HillsideTerraces and Trenches.png|345x324px|HillsideTerraces and Trenches.png]]<br> |
− | <br> | + | <br> |
|- | |- | ||
| | | | ||
− | ==== Water harvesting | + | ==== Water harvesting ==== |
| | | | ||
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*<u>Objectives</u>: 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'''. | *<u>Objectives</u>: 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'''. | ||
− | [[Image:LowCostWaterLifting.png| | + | [[Image:LowCostWaterLifting.png|474x287px|LowCostWaterLifting.png]]<br> |
'''<br>Low Cost Micro-ponds''' | '''<br>Low Cost Micro-ponds''' | ||
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*<u>Objectives</u>: A percolation pit is a structure, constructed on any marginal land with pervious soil, with the following objectives: | *<u>Objectives</u>: A percolation pit is a structure, constructed on any marginal land with pervious soil, with the following objectives: | ||
− | #'''Recharge the ground water'''<br> | + | #'''Recharge the ground water'''<br> |
− | #'''Enhance biomass production through improved water availability in the soil profile'''.<br> | + | #'''Enhance biomass production through improved water availability in the soil profile'''.<br> |
#'''Reduce runoff and subsequently erosion and land degradation'''. | #'''Reduce runoff and subsequently erosion and land degradation'''. | ||
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*<u>Objectives</u>: A percolation pond is a structure, constructed on any marginal land with pervious soil, with the following objectives:<br> | *<u>Objectives</u>: A percolation pond is a structure, constructed on any marginal land with pervious soil, with the following objectives:<br> | ||
− | #'''Recharge the ground water'''<br> | + | #'''Recharge the ground water'''<br> |
− | #'''Enhance biomass production through improved water availability in the soil profile'''.<br> | + | #'''Enhance biomass production through improved water availability in the soil profile'''.<br> |
#'''Reduce runoff and subsequently erosion and land degradation'''. | #'''Reduce runoff and subsequently erosion and land degradation'''. | ||
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*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'''. | *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'''. | ||
− | [[Image:DripIrrigation.png|350px|DripIrrigation.png]]<br> | + | [[Image:DripIrrigation.png|350px|DripIrrigation.png]]<br> |
'''<br>Roof Water Harvesting System''' | '''<br>Roof Water Harvesting System''' | ||
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*<u>Objectives</u>: 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 rehabilite 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.<br> | *<u>Objectives</u>: 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 rehabilite 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.<br> | ||
− | [[Image:Small Stone Bunds.png|600px|Small Stone Bunds.png]]<br> | + | [[Image:Small Stone Bunds.png|600px|Small Stone Bunds.png]]<br> |
<br>'''Narrow Stone Lines Along the Contour''' | <br>'''Narrow Stone Lines Along the Contour''' | ||
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*<u>Objectives</u>: 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. | *<u>Objectives</u>: 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. | ||
− | [[Image:NarrowStoneLinesAlongContours.png|350px|NarrowStoneLinesAlongContours.png]]<br> | + | [[Image:NarrowStoneLinesAlongContours.png|350px|NarrowStoneLinesAlongContours.png]]<br> |
<br>'''Stone Faced/Soil or Stone Bunds with Run-off/ Run-on Areas''' | <br>'''Stone Faced/Soil or Stone Bunds with Run-off/ Run-on Areas''' | ||
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*<u>Objectives</u>: 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 microcatchment 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. | *<u>Objectives</u>: 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 microcatchment 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. | ||
− | [[Image:Bunds with run-off areas.png| | + | [[Image:Bunds with run-off areas.png|455x309px|Bunds with run-off areas.png]] |
'''<br>Conservation Bench Terraces (s) (CBT(s))''' | '''<br>Conservation Bench Terraces (s) (CBT(s))''' | ||
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*<u>Objectives</u>: 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). | *<u>Objectives</u>: 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). | ||
− | [[Image:HalfMoons.png| | + | [[Image:HalfMoons.png|530x331px|HalfMoons.png]] |
− | '''<br>''' | + | '''<br>''' |
'''Division Weir Design and Construction''' | '''Division Weir Design and Construction''' | ||
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*<u>Objectives</u>: To divert stream flow for use during dry seasons for the purpose of small scale irrigation and for any other supplementary irrigation. | *<u>Objectives</u>: To divert stream flow for use during dry seasons for the purpose of small scale irrigation and for any other supplementary irrigation. | ||
− | <br> | + | <br> |
|- | |- | ||
| bgcolor="#990000" | | | bgcolor="#990000" | | ||
− | === '''<span style="color: rgb(255, 255, 255) | + | === '''<span style="color: rgb(255,255,255)">POLITICAL MEASURES</span>''' === |
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|- | |- | ||
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− | ==== [http://energypedia.info/index.php/Watershed_Action_Planning_related_to_MHP_projects_in_Ethiopia#Training Education and training] | + | ==== [http://energypedia.info/index.php/Watershed_Action_Planning_related_to_MHP_projects_in_Ethiopia#Training Education and training] ==== |
| bgcolor="#ffcc99" | <br> | | bgcolor="#ffcc99" | <br> | ||
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− | ==== Income generating measures | + | ==== Income generating measures ==== |
| <br> | | <br> | ||
|- | |- | ||
| bgcolor="#ffcc99" | | | bgcolor="#ffcc99" | | ||
− | ==== [http://energypedia.info/index.php/Watershed_Planning_Team_related_to_MHP_Projects_in_Ethiopia Participatory approach] | + | ==== [http://energypedia.info/index.php/Watershed_Planning_Team_related_to_MHP_Projects_in_Ethiopia Participatory approach] ==== |
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'''Box 1''' shows three examples of how (rather simple) interventions can improve the environmental condition of the catchment. A more detailed list of mitigation and intervention techniques and the respective application can be found in DESTA, L. ET AL. (2005): Part 1: ''Community Based Participatory Watershed Development. '' Addis Ababa: Ministry of Agriculture and Rural Development, pages 69 – 165 and DESTA, L. ET AL. (2005): Part 2: ''Community Based Participatory Watershed Development: Annex''. Addis Ababa: Ministry of Agriculture and Rural Development, pages 43 - 48. | '''Box 1''' shows three examples of how (rather simple) interventions can improve the environmental condition of the catchment. A more detailed list of mitigation and intervention techniques and the respective application can be found in DESTA, L. ET AL. (2005): Part 1: ''Community Based Participatory Watershed Development. '' Addis Ababa: Ministry of Agriculture and Rural Development, pages 69 – 165 and DESTA, L. ET AL. (2005): Part 2: ''Community Based Participatory Watershed Development: Annex''. Addis Ababa: Ministry of Agriculture and Rural Development, pages 43 - 48. | ||
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Springs and wetlands not only guarantee the discharge in dry season, also they have a great retention capacity during and after rains. Springs are sensitive areas that react to disturbances easily. Protection of springs and wetlands is thus crucial for the sustainable use of the MHP projects. Protection measurements might include fencing (to protect the areas from [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#Changes_in_soil_texture_and_cattle_step cattle step] and thus soil compaction), protection of [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#.C2.A0Deforestation_and_Destruction_of_Natural_Vegetation natural vegetation] around the springs, protection of a natural humus layer (in order to sustain sufficient infiltration and thus groundwater recharge). Furthermore fencing can help to improve the water quality, since pollution due to agricultural and pastoral use can be prevented<ref>HELVETAS (2005): Helvetas Wasser Fact Sheet: Quellen und Quellschutz.</ref>. | Springs and wetlands not only guarantee the discharge in dry season, also they have a great retention capacity during and after rains. Springs are sensitive areas that react to disturbances easily. Protection of springs and wetlands is thus crucial for the sustainable use of the MHP projects. Protection measurements might include fencing (to protect the areas from [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#Changes_in_soil_texture_and_cattle_step cattle step] and thus soil compaction), protection of [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#.C2.A0Deforestation_and_Destruction_of_Natural_Vegetation natural vegetation] around the springs, protection of a natural humus layer (in order to sustain sufficient infiltration and thus groundwater recharge). Furthermore fencing can help to improve the water quality, since pollution due to agricultural and pastoral use can be prevented<ref>HELVETAS (2005): Helvetas Wasser Fact Sheet: Quellen und Quellschutz.</ref>. | ||
− | ==== <br>'''Buffered vs. unbuffered riverbanks/wetlands<br>''' | + | ==== <br>'''Buffered vs. unbuffered riverbanks/wetlands<br>''' ==== |
A buffer typically consists of a band of vegetation along a wetland or water body, preferably natural habitat, but including previously altered, stable native or introduced species. A buffer can perform a variety of functions, which can improve the environmental condition of a watershed, such as sediment removal and erosion control, runoff reduction through infiltration, reduction of human impacts by limiting easy access as well as barrier to invasion of exotic species<ref>GALE, J.A. (unknown): Watershedss Wetland Management. http://www.water.ncsu.edu/watershedss/info/wetlands/manage.html#prot</ref>. Thus buffers can benefit the sustainable use of the MHP and should hence be established and/or protected. | A buffer typically consists of a band of vegetation along a wetland or water body, preferably natural habitat, but including previously altered, stable native or introduced species. A buffer can perform a variety of functions, which can improve the environmental condition of a watershed, such as sediment removal and erosion control, runoff reduction through infiltration, reduction of human impacts by limiting easy access as well as barrier to invasion of exotic species<ref>GALE, J.A. (unknown): Watershedss Wetland Management. http://www.water.ncsu.edu/watershedss/info/wetlands/manage.html#prot</ref>. Thus buffers can benefit the sustainable use of the MHP and should hence be established and/or protected. | ||
− | ==== <br>'''Eucalyptus vs. indigenous plants<br>''' | + | ==== <br>'''Eucalyptus vs. indigenous plants<br>''' ==== |
− | Eucalyptus easily adapts to any soil and water condition, it is characterized by fast growth, high survival, long roots and hard leafs. Those features make it economically very beneficial. When it comes to watershed management, its negatives sides should be considered though: it does not only take a lot of nutrients and water and is hence a high competition to companion plants and decreases biodiversity, also soil erosion can occur which can negatively affect the [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#Box_1: MHP’s performance]. FAO thus recommends that large scale monocultures of eucalypt plantations be excluded from watersheds, aforestation projects should avoid monocultures and the use of eucalypts. The only way to include eucalyptus is to adopt it in agroforestry systems, but the proportion of each species should be planned out carefully<ref>SUNGSUMARN, K. (1993): Why Eucalyptus is Not Adopted for Agroforestry. In: Kashio, M. et al. (Hrsg.)(1996): Reports Submitted to the Regional Expert Consultation on Eucalyptus - Volume II. Bangkok: FAO Regional Office for Asia and the Pacific.</ref>. | + | Eucalyptus easily adapts to any soil and water condition, it is characterized by fast growth, high survival, long roots and hard leafs. Those features make it economically very beneficial. When it comes to watershed management, its negatives sides should be considered though: it does not only take a lot of nutrients and water and is hence a high competition to companion plants and decreases biodiversity, also soil erosion can occur which can negatively affect the [http://energypedia.info/index.php/Causes_and_Features_of_Watershed_Degradation_related_to_MHP_Projects_in_Ethiopia#Box_1: MHP’s performance]. FAO thus recommends that large scale monocultures of eucalypt plantations be excluded from watersheds, aforestation projects should avoid monocultures and the use of eucalypts. The only way to include eucalyptus is to adopt it in agroforestry systems, but the proportion of each species should be planned out carefully<ref>SUNGSUMARN, K. (1993): Why Eucalyptus is Not Adopted for Agroforestry. In: Kashio, M. et al. (Hrsg.)(1996): Reports Submitted to the Regional Expert Consultation on Eucalyptus - Volume II. Bangkok: FAO Regional Office for Asia and the Pacific.</ref>. |
|} | |} | ||
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== References == | == References == | ||
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<references />Per __NOTOC__ | <references />Per __NOTOC__ | ||
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[[Category:Ethiopia]] [[Category:Hydro]] | [[Category:Ethiopia]] [[Category:Hydro]] |
Revision as of 07:29, 17 May 2011
The identification of appropriate mitigation and intervention techniques on the basis of the Environment Assessment is crucial for the implementation of a successful Watershed Action Plan in order to achieve a sustainable use of the catchment area and thus the MHP project. Biophysical as well as political mitigation and intervention techniques are listed in the table below:
BIOPHYSICAL MEASURES[1] |
|
Gully control |
Stone Checkdams
Brushwood Checkdams
Gully Reshaping, Filling and Revegetation
Sediment Storage and Overflow Earth Dams (SS Dams) for Productive Gully Control
|
Agro-forestry, Forage Development and Forestry |
Area Closure
Microbasins (MBs)
|
Soil Fertility Management and Biological Soil Conservation |
Compost Making
Fertilization and Manuring
Grass Strips along the Contours
|
Flood Control and Improved Drainage |
Waterways (Vegetative and Stone Paved)
Cut-off Drains
|
Physical Soil and Water Conservation |
Level Soil Bunds
|
Water harvesting |
Hand-dug Wells
Division Weir Design and Construction
|
POLITICAL MEASURES |
|
Education and training |
|
Income generating measures |
|
Participatory approach |
Box 1 shows three examples of how (rather simple) interventions can improve the environmental condition of the catchment. A more detailed list of mitigation and intervention techniques and the respective application can be found in DESTA, L. ET AL. (2005): Part 1: Community Based Participatory Watershed Development. Addis Ababa: Ministry of Agriculture and Rural Development, pages 69 – 165 and DESTA, L. ET AL. (2005): Part 2: Community Based Participatory Watershed Development: Annex. Addis Ababa: Ministry of Agriculture and Rural Development, pages 43 - 48.
Box 1:
|
References
- ↑ DESTA, L. ET AL. (2005): Part 1: Community Based Participatory Watershed Development: A Guideline. Addis Ababa: Ministry of Agriculture and Rural Development.
- ↑ HELVETAS (2005): Helvetas Wasser Fact Sheet: Quellen und Quellschutz.
- ↑ GALE, J.A. (unknown): Watershedss Wetland Management. http://www.water.ncsu.edu/watershedss/info/wetlands/manage.html#prot
- ↑ SUNGSUMARN, K. (1993): Why Eucalyptus is Not Adopted for Agroforestry. In: Kashio, M. et al. (Hrsg.)(1996): Reports Submitted to the Regional Expert Consultation on Eucalyptus - Volume II. Bangkok: FAO Regional Office for Asia and the Pacific.
Per