Groundwater Flow Model in Semarang Urban Area, Indonesia. Mohd Shalahudin ADNAN 1 , Heru HENDRAYANA 1 , Doni Prakasa Eka PUTRA 1 , Kenji JINNO 2 1 Geological Engineering Department, Yogyakarta. 2 Department of Urban and Environmental Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819- 0395, Japan. E-mail: mohdshalahuddin@yahoo.com Introduction Semarang is a city located in Central Java and it is also the capital city of Central Java. The population of this city is significantly increasing from 503,780 people (1990) to approximately 1,450,000 people in (2005) (BPS, 2005). The increasing of water demand is proportionally with the increasing of population. The water resources in this city mostly come from the surface water which is treated by PDAM and also from the springs and groundwater as well. Nowadays, the groundwater has been pumped out either from confined or unconfined aquifer to support the groundwater needs in this area. However, this activity can lead to many negative impacts on the groundwater in this area if there are no groundwater management was implemented. Many kind of groundwater management have been implemented to manage the groundwater to achieve groundwater sustainability. In this study, the researcher tends to use the modern technology to manage the groundwater in this area by using a computer code rather than the conventional ways. The rapid development of computer technology can be a useful tool to manage groundwater particularly by develop a model. It can be a powerful method for management purposes. Groundwater models are representation of reality and can be used to complement monitoring and laboratory bench studies in evaluating and forecasting groundwater flow system and mass transport. The groundwater result from the model simulation is expected to be a helpful data to support the groundwater management in this area. Study Area The research work was conducted in Semarang Urban Area, Indonesia. The hydrogeological boundary of this study area is limited by Banjir Kanal Timur River on the east, Banjir Kanal Barat River on the west, Java Sea on the North, and at the border of different morphology on the south which also act as the boundary of model area (Figure 1). The study area also limited by the administrative border as follows: - Semarang Utara on the north. - Semarang Timur on the east. - Semarang Barat on the west. - Semarang Selatan on the south. Figure 1: Location of study area. The Objectives of Study. Nowadays, there are many useful tools to support groundwater management. The tools can be either from technical or non-technical aspects. Groundwater management should be integrated with others disciplines to achieve a sustainable groundwater management. Groundwater modeling is the best tool to manage groundwater instead of by regulations as already implemented in the past. Hence, the purposes of research are:  Understanding of hydrogeological conditions, groundwater flow pattern, and characteristics of unconfined aquifer within the study area,  Develop conceptual model: idealize real groundwater flow system of study area.  Understand the groundwater balance in study area.  Simulating groundwater flow pattern.  Understand the hydraulic interaction between river and groundwater.