Requirements analysis is an important step in an information system development cycle. It can be viewed as a process with a life-cycle of its own. The requirements analysis may includes four more basic step: domain-problem analysis

problem description

prototyping and testing

validation. It is also an iterative and evolutionary process

and a concurrent activity. Therefore

the requirements analysis model should represent the iterative

evolutionary and concurrent characteristics of requirements process activities. However

most of models resently developed only represent one or two characters of requirements process activities. The waterfront model for requirements analysis which was put forward by Theofanos can represent all characters of requirements process activities. In this paper the authors improve this model according to the characters of GIS requirements analysis activities in following aspects: ① In order to develop ulteriorly the automatous tool of GIS requirements analysis in term of the model

the requirements analysis was partitioned into five basic activities: problem analysis

structural requirements description

formal requriements definition

prototyping and testing

validation. ② In order to make the model more operational

analysis methods for every activities of requirements analysis is put forward. ③ The difference of requirments analysis for project GIS

department GIS

enterprise GIS and social GIS is presented and also incorporated into the model. The methods for GIS structural requirements analysis are also discussed. This will have a guideline significance for GIS requirements analysis.