23 August 2011, Mutwaathi - Sub surface dam. FAO is assisting vulnerable farmers in drought-prone eastern Kenya prepare their fields and build water harvesting structures such as this sand dam in a nearby seasonal river through a voucher-for-work project. Farmers are given a voucher in exchange for each day of work. Half of the voucher can be redeemed for food at select local traders, while the other half is used to buy building materials for the community sand dams.