Appraisal and evaluation of water supply and sanitation projects : Ghana as a case study
Existing appraisal and evaluation methodologies provide for a separate assessment of technical, financial, economic, institutional, social and environmental aspects of projects without a unifying theory to combine these aspects into a single measure of project performance. Data Envelopment Analysis is proposed as a methodology for combining project input and output factors into a single efficiency score which could be used to rank projects. The efficacy of the methodology has been demonstrated in an application to data from the water supply and sanitation sector in Ghana. This study involved the selection of ten projects in Ghana (six in water supply and four in sanitation). Each project is a representative of large urban or small urban or large rural or small rural systems in operation in Ghana. Various technologies employed in the projects include: (a) For water supply: Conventional Water Treatment Plant Boreholes with Motorised Pumps Package Water Treatment Plant Drilled Wells with Handpumps (2 projects) Hand Dug Well (b) For sanitation: Conventional Sewerage Communal Ventilated Improved Pit Latrines for an Urban Community Communal Ventilated Improved Pit Latrines for Rural Communities Traditional Pit Latrine Data on technical, financial, economic, institutional, social and environmental factors were collected in a 30-month fieldwork in Ghana. The fieldwork involved extensive travelling visiting urban and remote rural communities operating various systems in the sector. The data collected were analysed to provide the basic information for Data Envelopment Analysis (DEA). DEA requires input and output data for each project to be used in formulating linear programming models which are subsequently solved using a personal computer to provide an efficiency score for each project. Four different formulations were investigated and the results used to identify which projects could be classified as efficient given the Ghanaian context in which they are operated. Suggestions for the improvement of inefficient projects are made using the efficient projects as models. In conclusion DEA is recommended as a useful tool in appraisal and evaluation of water supply and sanitation projects to be adopted in developing countries, developing banks and other aid donor agencies. Other specific recommendations are made for the water supply and sanitation sector in Ghana.