Recently, studies for the development of low-lying areas including swamps have become very important not only in Indonesia but also worldwide. Authors focused on drainage problems during heavy rainfall. Among the methods employed, mathematical model simulation of unsteady hydrological and hydraulic phenomena was adopted. This technology can be used not only for analyzing the present conditions of drainage, but also for evaluating plans for drainage improvement. The mathematical model should be modified to analyze hydrological runoff characteristics and operation rule of drainage facilities in Indonesia. The improvement of the drainage system must be performed in collaboration with the farmers and inhabitants. Methods of drainage analysis should be selected according to the respective stages of improvement.