Reservoirs Stepping down a Dry-Zone Valley

Reservoirs Stepping down a Dry-Zone Valley is an original illustration set in Palugaswewa Tank-Village System, Sri Lanka. It lies in equatorial latitudes, where the climate is tropical savanna — a pronounced dry season.

From a high oblique view, several shallow village tanks step down one winding drainage line through dry-zone woodland. Earthen bunds hold lotus water, overflow spills toward the next basin, paddy fields occupy the damp valley floor below each tank, and tree belts separate hamlets, grazing ground, and cultivated plots.

Why do many small reservoirs form a chain instead of one large lake?

A cascade stores irregular monsoon runoff repeatedly as water descends a small catchment: an upper tank slows and settles flow, its excess feeds the next, and sluices release water to paddies below each bund. Forest strips reduce erosion, vegetated seepage zones intercept salts, and connected tanks spread drought risk among villages. That sequence of water, bund, paddy, and tree buffer is the dry-zone tank-village logic of Sri Lanka.

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