Assuring adequate water supply in terms of quantity and quality is one of the major issues in both rural and urban development. Supply reservoirs are often located outside urban areas, either as natural lakes and ponds or as man-made reservoirs specifically built for that purpose. This situation is very similar in both China and the Netherlands. The reservoirs clearly depend on natural replenishment by capturing rainfall or assuring adequate river inflows. Due to seasonal variability, the inflow may vary considerably in time, requiring proper studies of the hydrological conditions when designing reservoirs. Also, the effects of climate change may lead to consecutive years of water shortage, which requires even more adequate design of storage reservoirs to assure water supply during the intermittent periods. However, many problems occur in water storage reservoirs. Due to urbanization, agriculture, industrial processes, water quantity and quality in storage reservoirs become unpredictable. To care these problems need lots of time and money, but funds are limited to restoring water ecology in many developing countries. Therefore, how to predict water quantity and quality inside storage reservoirs in order to reduce damages becomes more and more important. In this MSc research, the focus is on a case study for the Lake IJsselmeer in the middle of the Netherlands where cities like Amsterdam, Haarlem and Alkmaar are situated. PWN Water Supply Company uses the IJsselmeer as a source of drinking water production. This lake can represent many water supplying reservoirs, like Taihu Lake in China, because both of them are prone to external influences, including fluctuation in water quantity and quality, groundwater intrusion, currents, wind effects and so on. Therefore, based on this study case, this thesis tries to investigate and evaluate the opportunities and limitations of the currently available model suite developed by Deltares (Delft3D) on simulating water quantity and quality in storage reservoirs. In this thesis, ...