This paper presents the results of an evaluation of the effects of a local water harvesting project in Kenya concerning the construction
of small scale sand dams by communities. Sand dams are small structures built in ephemeral rivers to store excess water to overcome
periods of drought. For this evaluation we developed a method using socio-economic vulnerability indicators, which are linked to the
state water resources system, enabling the assessment of the impacts of changes in water management. Data for this evaluation was gathered
by hydrological research and by interviewing local inhabitants during field research. It appeared that the sand dams have a large
impact on the local community. In 10 years time, more than 100,000 people have better access to water through a relative low cost measure.
The increased water availability, especially during dry periods, results in higher farm yields. The average income of farmers living
near dams rose with 60%. The local water balance is almost not influenced as the sand dams store less than 3% of total yearly runoff.