Miro catchment

basic understanding of micro catchment and its various types

1. MICRO- CATCHMENT PROJECT MO HD ISMAIL UL HAQ 3GN16CV060

2. CATCHMENT ? Catchment is an area where water is collected naturally by the landscape due to rainwater or surface run off

3. WHAT IS MICRO-CATCHMENT A micro-catchment is a specially contoured area with slopes and berms designed to increase run off from rain and concentrate it in a planting basin where it infiltrates and is effectively “stored” in the soil profile. The water is available to plants but protected from evaporation

4. PRINCIPLE Plants and trees are surrounded by stones or ridges that collect rainwater and surface run-off Collecting run-off by constructing basins to prevent water run off to allow it to infiltrate into soil profile and use it for further use like irrigation while enhancing soil contents and increasing ground water table by creating low soil ridges or optional stone walls

5. MAIN CHARACTERISTICS Over land flow harvested from short catchment length Catchment length usually is between 1 and 30 m Runoff water is stored in soil profile Ratio catchment:cultivated area usually lies between 1:1 to 3:1

6. Plant growth observed is even Works well on gentle slope ideally less than 5% A steeper slope only in case of very small catchment basin Normally no provision for overflow is provided plant/crop growth in unfavourable condition is possible

7. TYPES OF MICRO-CATCHMENT Negarim/ v-shaped micro-catchment (for trees) Contour bunds (for tree) Contour ridges (for crops) Semi-circular bunds(for ranges and fodder) Run off basins

8. NEGARIM Also known as v shaped micro-catchment Short slope catchment for trees and grass V shape is formed by small ridges with infiltration pits Rainfall can be as low as 150mm per annum Depth of soil should be at least 1.5-2m for proper infiltration Each micro catchment consists of catchment area and infiltration pits

9. LIMITATIONS Not easily mechanised once the tree is planted it is not possible to operate and cultivate with machines trough the tree lines. Cost increases as the size of micro catchment increases

10. CONTOUR BUND This is used to grow trees and grass over contours Each bunds on contour spaced at 5-10m apart with furrow up-slope and cross ties Is mechanised method can be used to plant over large catchment area A minimum of 200mm of rainfall is required in semi arid regions and more in arid regions Common size of catchment is 10-50 meter-sq

11. LIMITATION Not suitable for eroded land forms Sustainability is an issue with high cost of maintenance for repair of bunds

12. CONTOUR RIDGES Also known as micro-water shed, used for growing crops Small earth ridges on contour at an interval of 1.5 to 5m apart are constructed with up slope furrow and cross ties and uncultivated catchment between ridges For production of crops with fertile soil usually in semi arid regions Annual rainfall should be between 300-700mm Catchment:cultivated area ratio is usually 2:1

13. LIMITATIONS Bunds are required to be repaired every season contour ridges are limited to area with high rainfall and cultivated area is small leading to small harvest

14. SEMI CIRCULAR BUNDS These are earth embankments in the shape semicircle with the tip of bund on semicircle These are used for growing fodder, shrubs and in some cases trees About 200-750mm rainfall is required and slopes below 2% is preferred Bunds can either be made narrow and closely spaced or large and wider spaced Radii of bunds varies from 6-20m with C:CA 3:1

15. BUND MADE WITH SOIL BUND MADE WITH STONES

16. ADVANTAGES A Micro-catchment system has many advantages over other water harvesting and irrigation systems Micro catchments are simple and inexpensive to construct Soil fertility is increased by trapping organic matter in the soil due to surface run-off Many number of crops and plants can be grown simultaneously Maintenance cost is very low Most effective method of water harvesting in arid regions Increased crop yield and provide erosion control functions

17. LIMITATION Requires deep soil profile at least 2 metre deep Bunds need to be repaired constantly due bund breaking Applicable at only small scale since implementation process is not easily mechanised unsustainably due to various reasons and lack of knowledge is a big issue Cost of construction and maintenance increases as the catchment size increases

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