DAM CATCHMENT RESTORATION EROSION PREVENTION AND RESPONSE

Abstract

Siandwazi Village, located in southern Zambia, is a community of smallholder farmers who rely on a community dam for dry season water supply and food production. Gully erosion is occurring on the dam spillway and in its watershed due to the dam’s influence on stream gradient and agricultural land-conversion. A community-led, volunteer erosion control program was conducted throughout the 2019/20 rain season to protect the dam from erosion-derived failure and re-establish natural hydrological regimes. Erosion control efforts on the spillway reduced annual gully and rill erosion from 10.5 to 2m3/yr through the placement of rock, sand-filled sacs, and vetiver grass (Vetiveria zizanioides). Erosion prevention and control efforts in the watershed were planned but never proceeded due to labour constraints and drought-derived socioeconomic challenges, therefore erosion increased from 12 to 14.5m3/yr. Construction on a flood-mitigating check dam was initiated and a baseline run-off coefficient was established to allow for specific watershed objective-setting moving forwards into next rain season.