This book is an attempt to reveal the flow characteristics, hydrogeochemistry, and its relation to the water aggressiveness level in dissolving the karst limestone, as well as to study the behavioural components of Karst Dynamic System (KDS) in Bribin Underground River, Gunung Sewu Karst, Indonesia. The research’s result demonstrates that there is spatial and temporal differentiation of flow characteristics along Bribin River attributable to the comportment of karst aquifer toward discharging its diffuse, fissure, or conduit flow components, which consequence to the dissimilarity of diffuse flow proportion (PAD) distribution along Bribin River. Accordingly, PAD characteristics result to dry season hydrogeochemical condition of Bribin River. However, wet season hydrogeochemical condition is more influenced by means of dilution by precipitation process within flood events, which exaggerates CO2 content of water. Generally, the upper-stream cave tend to more aggressive in dissolving limestone, contrast to down-steam cave that be inclined to precipitate carbonate mineral as a result of their differentiation of cavities configuration.