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Ancient Ellangawa (tank cascade) micro-catchments: Godawala and Kattakaduwa zoning?

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M
Mia•925 rep

What distinct ecological functions do the Godawala (silt trap) and Kattakaduwa (interceptor vegetative buffer) serve in ancient tank cascade watershed networks?

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✓Accepted Answer

An Ellangawa is an interconnected network of small village irrigation tanks organized within a meso-catchment basin, recognized by the FAO as a Globally Important Agricultural Heritage System (GIAHS). The system relies on specific land-use buffer zones: The Godawala is a small upstream silt-trapping pit built at the water inlet of the main reservoir to capture eroded soil from chena slopes before it settles into the primary water storage area. Downstream of the main earthen bund lies the Kattakaduwa—a dense vegetative bio-filter strip planted with salt-absorbing species (such as Kumbuk, Vetiver, and Karanda) that absorbs excess soil salinity and iron compounds, ensuring that seepage water entering adjacent paddy fields is balanced for cultivation.

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E
Eng Karunaratne•1840 rep

Encroaching into the Kattakaduwa zone with modern tractor paths destroys the salt-filtering vegetation, causing secondary soil salinization in low-lying paddy tracts.

20
M
Mia•925 rep

Restoring ancient tank cascade systems provides climate resilience against erratic monsoonal cloudbursts followed by prolonged dry-zone droughts.

18
P
Pradeep•1640 rep

Upstream catchment tree zones (Wew-thaulla) shade the shallow water margins, minimizing evaporation losses during dry inter-monsoon months.

16
G
Gunasena Farmer•1750 rep

Archaeological surveys in the Malwathu Oya basin confirm that these cascade networks have functioned continuously for over two thousand years.

14
P
Prof Gamini•1890 rep

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