Evaluation of catchment basin design and water quality in southern Madagascar

To cope with the consequences of recurrent droughts in southern Madagascar, CARE International is coordinating several emergency interventions in the districts of Amboasary and Fort-Dauphin, including the construction of rainwater catchment basins. Several questions were raised concerning:
– High evaporation rate because surface is exposed to the sun;
– Poor quality of water supplied for consumption;
– Risk of increase in malaria rate.
PRACTICA provides technical support to CARE to assess the issues raised and propose appropriate corrective technical options appropriate to the context of the intervention.


  • Assess the effectiveness and health risks of catchment basins
  • Formulate appropriate technical solutions to solve the shortcomings and problems observed


  • Quantification of the evaporation at basin level
  • Characterisation of water quality (potability, degree of contamination, filterability)
  • Assessment of the impact of basins on mosquito proliferation and development of malaria in neighbouring villages
  • Detailed technical proposals for the redevelopment of existing basins and the design of future models




  • Water from the basins does not meet Malagasy water quality standards for drinking water
  • Household water treatment is recommended for the short term (e.g. biosand filter, ceramic filter, Sur’Eau (chlorine), SODIS)
  • Long term options: low-cost well drilling or the addition of an impluvium as a clean water collection surface