This chapter discusses geographical information system (GIS) modelling in relation to land suitability and water management zoning of tidal lowlands. This modelling will be used especially to support planning activities in relation to a sustainable development of tidal lowlands. The land suitability and water management zoning is one of the thematic information in relation to the agricultural potential. The method of natural resources management by using the GIS in combination with remote sensing techniques is a new and improved way of assessment. The GIS system in fact is a kind of expert system where a great number of data are stored in the central core of the model and which is used to make judgements based on digital image processing. Multi-criteria decision making in the GIS is concerned with how to combine the information from several maps to form a single index of the evaluation result.