The following well characteristics were initially fitted to the model: village of location, age of the artesian well, age of the shallow well, internal diameter of the shallow well, depth of air column, water depth, type of delivery pipe, presence of a rusted iron ladder, presence of surrounding rubbish, presence of a cover over the well, area receiving irrigation, type and power of engine, months when the well was usually used for irrigation, number of years since the last use, time since the previous rainfall, frequency of entering the well in the previous year, and the type of soil surrounding the well.