Difference between revisions of "Mitigation and Intervention Techniques Related to Micro-hydro Power (MHP) Projects"
***** (***** | *****) |
***** (***** | *****) m |
||
Line 1: | Line 1: | ||
− | |||
[[Portal:Hydro|►Back to Hydro Portal]] | [[Portal:Hydro|►Back to Hydro Portal]] | ||
Line 85: | Line 84: | ||
=== '''Gully Reshaping, Filling and Revegetation''' === | === '''Gully Reshaping, Filling and Revegetation''' === | ||
− | *<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 | + | *<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 leveled 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. |
[[File:GullyReshapingRevegetation.png|left|230px|GullyReshapingRevegetation.png|alt=GullyReshapingRevegetation.png]]<br/><br/><br/> | [[File:GullyReshapingRevegetation.png|left|230px|GullyReshapingRevegetation.png|alt=GullyReshapingRevegetation.png]]<br/><br/><br/> | ||
Line 166: | Line 165: | ||
=== <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 ''' | + | *<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 '''stabilization, 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 adaptability 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. |
<br/> | <br/> | ||
Line 183: | Line 182: | ||
=== '''Fertilization and Manuring''' === | === '''Fertilization and Manuring''' === | ||
− | *<u>Objectives</u>: The current cropping systems in Ethiopia | + | *<u>Objectives</u>: The current cropping systems in Ethiopia is highly organic as chemical fertilizers are expensive and not always readily available. Manure is used in most areas as fuel or income source. As open grazing manure is not readily available,mulching is not practiced. Furthermore,the crop residues is also used for forage. Low levels of organic matter are leading to reduced soil stability, infiltration, water holding capacity and increasing erosion. Application of fertilizers will '''increase yields''', while manure and mulching will '''improve long term soil quality and nutrient levels'''. |
− | === <br/>'''Live | + | === <br/>'''Live Check dams''' === |
*<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. | ||
Line 193: | Line 192: | ||
=== <br/>'''Mulching and Crop Residues Management''' === | === <br/>'''Mulching and Crop Residues Management''' === | ||
− | *<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 ''' | + | *<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 '''minimizes 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. |
[[File:Mulching.png|230px|Mulching.png|alt=Mulching.png]] | [[File:Mulching.png|230px|Mulching.png|alt=Mulching.png]] | ||
Line 207: | Line 206: | ||
=== <br/>'''Stabilization of physical Structures and Farm Boundaries''' === | === <br/>'''Stabilization of physical Structures and Farm Boundaries''' === | ||
− | *<u>Objectives</u>: Stabilization refers to the planting of crops, grass, shrubs and trees in different combinations<br/>in order to '''strengthen the resistance and stability of physical structures such as bunds, trenches, | + | *<u>Objectives</u>: Stabilization refers to the planting of crops, grass, shrubs and trees in different combinations<br/>in order to '''strengthen the resistance and stability of physical structures such as bunds, trenches, check dams, SS dams, etc, against rain drops splash effect, runoff and cattle trampling'''. At the same time, stabilization has the purpose of making productive the surface area occupied by the structure. Stabilized structures would need less maintenance and damages are less likely to occur, even during heavy rainstorms. Trees or shrubs help to demarcate farm and homestead boundaries, thus provide additional sense of ownership. Particular plants are also hosts for insects able to control pest incidence. Stabilized areas are an additional source of timber, fuelwood, fiber, food and forage, palatable grasses and legumes, fruits and other products (dyes, gum, medicinal, etc.). |
=== <br/>'''Vegetative Fencing''' === | === <br/>'''Vegetative Fencing''' === | ||
Line 252: | Line 251: | ||
=== '''Waterways (Vegetative and Stone Paved)''' === | === '''Waterways (Vegetative and Stone Paved)''' === | ||
− | *<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, | + | *<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, reservoirs 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 accommodating 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. |
[[File:Waterways.png|391px|Waterways.png|alt=Waterways.png]]<br/> | [[File:Waterways.png|391px|Waterways.png|alt=Waterways.png]]<br/> | ||
Line 267: | Line 266: | ||
=== <br/>'''Graded Soil Bund''' === | === <br/>'''Graded Soil Bund''' === | ||
− | *<u>Objectives</u>: Graded soil bund is similar in description with level soil bund. However, graded soil bund is upto a maximum of 1% inclined against the contour so that excess runoff is allowed to drain to the adjoining natural or artificial waterways. It is also possible and necessary to | + | *<u>Objectives</u>: Graded soil bund is similar in description with level soil bund. However, graded soil bund is upto a maximum of 1% inclined against the contour so that excess runoff is allowed to drain to the adjoining natural or artificial waterways. It is also possible and necessary to include tied ridges smaller in height within the channel of the terrace. The stored water within the ties can infiltrate into the soil while any above that height is drained out. Graded soil bunds can be made to gradually develop in to benched type terraces through careful maintenance. Any integration of other measures such as stabilization and composting can be applied as it can be applied on level bunds.<br/> |
=== <br/>'''Graded Fanya Juu''' === | === <br/>'''Graded Fanya Juu''' === | ||
− | *<u>Objectives</u>: The GFJ with a maximum gradient of 1% | + | *<u>Objectives</u>: The GFJ with a maximum gradient of 1% discharges excess runoff generated from the inter terrace spaces to the adjoining natural or artificial waterway at a non-erosive velocity. This consequently '''reduces runoff and soil erosion'''. It is also possible to include tied ridges smaller in height within the channel of the terrace. The stored water within the ties can infiltrate into the soil while any excess above that height is drained out. Graded fanya juu bunds can be made to gradually develop in to benched type terraces through maintenance. |
=== <br/>'''Improved Surface Drainage for Increasing Productivity of Vertisols and Soils with Vertic Properties''' === | === <br/>'''Improved Surface Drainage for Increasing Productivity of Vertisols and Soils with Vertic Properties''' === | ||
Line 353: | Line 352: | ||
=== <br/>'''Low Cost Micro-ponds''' === | === <br/>'''Low Cost Micro-ponds''' === | ||
− | *<u>Objectives</u>: Supplementary irrigation to high value crops (horticulture, fruit trees, etc.). Water for livestock for a few months. | + | *<u>Objectives</u>: 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. |
=== <br/>'''Underground Cisterns''' === | === <br/>'''Underground Cisterns''' === | ||
Line 403: | Line 402: | ||
=== <br/>'''Small Stone Bunds with Run-on and Run-off Areas''' === | === <br/>'''Small Stone Bunds with Run-on and Run-off Areas''' === | ||
− | *<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 | + | *<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 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.<br/> |
[[File:Small Stone Bunds.png|300px|Small Stone Bunds.png|alt=Small Stone Bunds.png]]<br/> | [[File:Small Stone Bunds.png|300px|Small Stone Bunds.png|alt=Small Stone Bunds.png]]<br/> | ||
Line 415: | Line 414: | ||
=== <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''' === | ||
− | *<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 | + | *<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 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. |
[[File:Bunds with run-off areas.png|125px|Bunds with run-off areas.png|alt=Bunds with run-off areas.png]] | [[File:Bunds with run-off areas.png|125px|Bunds with run-off areas.png|alt=Bunds with run-off areas.png]] | ||
Line 433: | Line 432: | ||
=== <br/>'''The Zai and Planting Pit System''' === | === <br/>'''The Zai and Planting Pit System''' === | ||
− | *<u>Objectives</u>: 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 | + | *<u>Objectives</u>: 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. |
[[File:Zai and Planting Pits.png|500px|Zai and Planting Pits.png|alt=Zai and Planting Pits.png]] | [[File:Zai and Planting Pits.png|500px|Zai and Planting Pits.png|alt=Zai and Planting Pits.png]] | ||
Line 507: | Line 506: | ||
<references /> | <references /> | ||
+ | [[Category:Micro_Hydro]] | ||
[[Category:Hydro]] | [[Category:Hydro]] | ||
− |
Revision as of 13:38, 19 August 2014
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:
POLITICAL MEASURES
BIOPHYSICAL MEASURES[1] |
|
Gully control[1] |
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[1] |
Area Closure
Microbasins (MBs)
|
Soil Fertility Management and Biological Soil Conservation[1] |
Compost Making
Fertilization and Manuring
|
Flood Control and Improved Drainage[1] |
Waterways (Vegetative and Stone Paved)
Cut-off Drains
|
Physical Soil and Water Conservation[1] |
Level Soil Bunds
|
Water harvesting[1] |
Hand-dug Wells
|
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:
|
Further Information
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 DESTA, L. ET AL. (2005): Part 1: Community Based Participatory Watershed Development: A Guideline. Addis Ababa: Ministry of Agriculture and Rural Development. Cite error: Invalid
<ref>
tag; name "desta" defined multiple times with different content Cite error: Invalid<ref>
tag; name "desta" defined multiple times with different content Cite error: Invalid<ref>
tag; name "desta" defined multiple times with different content Cite error: Invalid<ref>
tag; name "desta" defined multiple times with different content Cite error: Invalid<ref>
tag; name "desta" defined multiple times with different content Cite error: Invalid<ref>
tag; name "desta" defined multiple times with different content - ↑ 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.