Semicircular bund

A semi-circular bund (also known as a demi-lune or half-moon) is a rainwater harvesting technique consisting in digging semi-lunar holes in the ground with the opening perpendicular to the flow of water.

Beyond their primary function of reducing runoff for agricultural purposes, these methods offer additional benefits, such as providing extra drinking water for livestock, enabling land reclamation, enhancing soil fertility, accelerating timber growth for firewood, and influencing regional atmospheric patterns, potentially leading to increased precipitation.

[6] While the practice has ancient roots, semi-circular bunds gained significant attention in the scientific and development communities during the latter half of the 20th century, especially in the Sahel region of Africa.

Research conducted in the early 21st century has further validated the effectiveness of semi-circular bunds in improving soil properties, increasing vegetation cover, and enhancing biodiversity in arid and semi-arid ecosystems.

[10] In addition to their primary function of capturing rainfall, the accumulated detritus attracts termites and other invertebrates, whose activity creates tunnels and pores in the organic matter.

[11][12] When combined with other nutrient rich material such as animal manure, semi-circular bunds have been shown to significantly reduce the risk of crop failure and boost agricultural productivity—potentially tripling yields compared to more conventional methods.

In March 2023, the Wyss Academy for Nature in partnership with the Naibunga Community Conservancy and Justdiggit, started a project introducing semi-circular bunds to the Ewaso Ng’iro basin in Kenya.

[16] A 2014 study was conducted to investigate the effects of semi-circular bunds on vegetation cover and soil properties in Koteh rangeland, Sistan and Baloochestan province in Iran.