INTERPRETATION OF THE BEHAVIOR OF AGROWELL SYSTEMS IN SRI-LANKA USINGRADIAL FLOW MODELS

This paper describes a study of the use of large diameter ''agrowells' ' used for irrigation in Sri Lanka. Detailed field information for a s ingle location is presented and a numerical radial flow model was used to interpret the field response. Initially the model was used to repr esent a pumping test in which the pumping and subsequent recovery were monitored. It was then used to investigate the operation of the well during a dry season. Satisfactory agreement could only be obtained whe n account was taken of the withdrawal of water from below the water ta ble by trees. From the simulation it was possible to show that skilful farming practice could be used in steadily exploiting the resources f or irrigation over the whole of the dry season.