Main characteristics

• overland flow or rill flow harvested
• diverted from hillsides, pasture land, forests or roads and settlements
• runoff usually stored in the soil or in storage facilities
• catchment usually 30: 200 meters in length
• size of catchment from 0.1: 200 ha
• catchment: application area ratio 10:1 100:1
• runoff coefficient relatively low: 0.1 to 0.5 (10 – 50% of annual rainfall); the longer the catchment the lower the coefficient
• provision for overflow of excess water
• cropping area terraced on slopes or in flat terrain
• suitable for annual and perennial crops tolerant of temporary waterlogging or rapidly maturing on residual moisture
• nutrients harvested from accumulated sediments and washed-in animal droppings
• no control over catchment area because located outside farm boundaries

Main benefits

• Improved crop yields
• Improved year-round access to water for domestic and livestock consumption, as well as for supplementary irrigation
• Reduced risk of crop failure by bridging prolonged dry periods and as such contribute to food security and climate change adaptation.
• Reduced damage from soil erosion and flooding by storing excess runoff water

Main disadvantages

• Open and shallow rainwater ponds and dams may dry out after the rainy seasons, as the water is lost via seepage (except for rock catchment and sand dams) and evaporation
• Health risks: open storage structures can be contaminated by animals and can provide a breeding ground for disease-carrying insects. Sand dams are often contaminated as they are seldom protected from animals

(Mekdaschi & Liniger 2013, Critchley & Siegert 1991, African Development Bank 2009, Liniger et al. 2011, Critchley & Gowing 2012, Oweis et al. 2012)