Sand Dams & Drylands: Small solutions; big impacts. Simon - PowerPoint PPT Presentation

Sand Dams & Drylands: Small solutions; big impacts. Simon Maddrell Founder, Excellent Development SandDamMan@btinternet.com www.excellent.org.uk

About Excellent Development • Supports community-led rainwater harvesting and sustainable agriculture in rural drylands. • Pioneers of the application of sand dams in different contexts: Eight countries with agricultural and pastoral communities • Kenya (Ukambani & Northern Rangelands), Tanzania, Sudan, Chad, Zimbabwe, Mozambique, Swaziland & India. • Enabled communities to construct 900+ dams since 2002 • Almost 1 Million people with access to clean water. www.excellent.org.uk

Where do sand dams work? Sand Dams are a drylands solution requiring: • Sufficiently seasonal rivers • Sufficiently sandy sediment • Accessible bedrock www.excellent.org.uk

Technical sustainability – life cost • Along with sub-surface dams are the most cost-effective form of rainwater harvesting in drylands (UNDP). • Virtually zero operation and maintenance costs: • Last over 50 years • 5% need one-off repairs • 2% failure rate (80% of which have been repaired) Built 1985 Drank 2013 Built in Mwala District, Kenya, 1957. www.excellent.org.uk

Technical sustainability – design Breaking the rules to manage dryland seasonal river flows: • Enabling the river to flow in the same way as before: • Central spillways. • Dams not always straight. • Managing river floods with multiple spillways. www.excellent.org.uk

Social sustainability – community ownership • Community registered, built and managed. • If there is a hand pump – communities charge for water and maintain the pump. 2 Million days invested in self-help projects since 2002 www.excellent.org.uk

Social sustainability – reinvesting time Saving 2-10 hours per day enables communities to invest in sustainable development of their land. 2 Million days invested in self-help projects since 2002 Saved nearly 1 Billion hours collecting water since 2002 Sustainable Land Management 7

Environmental sustainability Virtuous Cycle of Soil & Water Conservation Terraces Maintain water Retain more & soil in farms water & soil in farms Water for people, Sand livestock, Trees vegetables Dams & tree nurseries www.excellent.org.uk

Advantages of sand dams Water yields up to 40M litres per annum Water protected from: • Contamination. • Evaporation. • Disease vectors, such as Bilharzia-carrying snails, and mosquitoes. www.excellent.org.uk

Clean water for people Nearly 1 Million People since 2002 Saving time: bringing clean water* to within 30-90 mins of people’s homes. Multi-Use Water Source

Irrigation of smallholder farms Nearly 1 Million Trees since 2002 • Demonstration farms. • Vegetable plots. • Tree nurseries. • Community plots and individual plots. Multi-Use Water Source

Water for livestock & wildlife Multi-Use Water Source

Sand dam in Rajasthan, India • Primarily a sub-surface dam (6m deep & 0.9m high) • Created an earth dam wing by scooping out the bend www.excellent.org.uk

Recharge & salinity reduction in India • Sand dams are recharging 3 govt. tube wells in one village in Rajasthan – doubling output and removing salinity. • 100 smallholder farmers irrigating more land and producing vegetables for the first time. www.excellent.org.uk

Potential of sand dam road crossings Potential to leverage infrastructure investments for the benefit of water supply and agriculture www.excellent.org.uk

Sand dams as rural road crossings Sand Dam road crossing, Machakos, Kenya Serves nine villages with est. 40M litres/annum www.excellent.org.uk

Problems with culvert bridges in drylands • Culverts unable to handle seasonal river flows • Exacerbated by blockages from river flotsam www.excellent.org.uk

Sand dam rural road crossing Makueni County, Kenya • Road crossing with four commercial farms next to the dam. www.excellent.org.uk

Water for year-round smallholder irrigation Makueni County, Kenya in November 2014 • Commercial farm growing ‘out of season’ maize, vegetables, papaya etc. www.excellent.org.uk

Sand dams: Small solutions; big impacts. Simon Maddrell Founder, Excellent Development SandDamMan@btinternet.com www.excellent.org.uk

Small dams support smallholder farmers • More than 2 billion people depend on smallholder farms, which provide 80% of the food Ψ • Smallholder farmers are 71% of the world’s poorest people* 75% of the world’s poor live in drylands § • The World Bank acknowledges that small-scale dams & smallholder farmers are an essential part of the solution to global hunger and poverty.  Small-scale dams:  Sand dams, check dams, sub-surface dams, water-spreading weirs * UNEP 2013 Ψ IFAD 2011 § UNCCD www.excellent.org.uk