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  • Writer's picturetribepermaculture

Watershed Management

Updated: Sep 12, 2022


Water management is critical on any landscape to meet the site requirements especially when there is less rainfall and less underground water available for irrigation during critical stages of the crop.

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With climate change and erratic rainfall patterns, it becomes important to build farm ponds to address water issues and improve livelihood.


*CATCH AND STORE ENERGY*

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Below factors need to be considered for a well-designed farm pond focussing on both the onsite and offsite effects:

-The hydrology of the catchment,

-Rainfall-Runoff relationship,

-Water requirement for crops and other uses

-Expected seepage

-Evaporation loss.

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Once analysed, the decision can be made on dimensions of the ponds, side slopes, and water control structures.

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A simple formula for calculating the volume of an excavated pond of any shape

V= ((A+4B+C)÷ 6)*D


A - Area of excavation at ground level

B - Area of excavation at middle depth of pond

C - Area of excavation at the bottom of the pond

D - depth of the pond


For this Pond:

A = π×5.8 = 18.21 sq.m

4B= 4×π×4 = 50.24 sq.m

C= π×2.2 = 6.90 sq.m

D = 1.8

V = (18.21+50.24+6.9)×1.8 / 6 = 22.6 CuM


Side Slope of farm ponds -based on the angle of repose of the material being excavated.

1.5:1 to 2:1 for clay soils (horizontal:vertical)

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Runoff volume = catchment area * avg rainfall * runoff coefficient.


Runoff volume to this pond =

4000sq.m × 1.5m * 0.4 = 2400 CuM


The runoff coefficient varies according to the hydrology of the catchment, slope, vegetation, and other factors.

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1cubic feet holds 28.3 litres of water

1cubic metre holds 1000litres of water.

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Farm pond lining is critical to control seepage and percolation losses.

Heavy clay which is available naturally on this site is selected for lining the pond.

Water loss through seepage in clay lining is 12 L/hr/m^2 (CRIDA)



Happy water harvesting!!



91 views3 comments

3件のコメント


Anuj Adkar
Anuj Adkar
2021年5月05日

Nice article...

What would you suggest about construction and refilling of pond on a flat land...?

いいね!
Anuj Adkar
Anuj Adkar
2021年5月06日
返信先

Ohk got it thanks...

いいね!
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