Critical analysis of the alternating direction implicit method of aquifer analysis

The alternating direction implicit method, when used for aquifer analysis, is liable to lead to erroneous results. By a careful examination of the effect of various factors, such as external boundaries, variable mesh intervals, internal boundaries with fixed heads, re-entrant boundaries and leakage, the occasions when these errors are serious have been identified. Techniques are described which can avoid these errors and lead to reliable numerical solutions.