Since coined in 2011, socio-hydrology studies have been dominated with mathematical models developed by mostly hydrologists, which often did not take social aspects into account so seriously. Some people argued that more attention into the social part of socio-hydrology should be given, because often the social aspects were too oversimplified. This thesis research tried to dig deeper into the social aspects of a socio-hydrology system. Keduang sub-basin was chosen to be the case study, as it has a sedimentation problem which has caused a huge operational problem of Gajah Mungkur dam, a multipurpose dam that mainly works as a flood control and hydropower plant in Solo river basin, the largest basin in Java Island of Indonesia. This research used the case study research approach proposed by Yin (2013). Three different analysis were done to examine the system: stakeholder analysis to identify the relevant actors and their characteristics, historical events analysis to examine what the actors have done that were related to the sedimentation issue, and Socio-cultural, Technological, Economic, Environmental, Political, Legal and Ethical (STEEPLE) analysis, to investigate those each sectors as external factors that might influence the decision making of the related actors. To summarize the analysis, a conceptual model was created to describe the socio-hydrology system of Keduang sub-basin. There are a total of 10 relevant actors in the system, which come from 3 different groups: government, society and external actors. The government consists of 7 government agencies, the society represents farmers, and the external factors consist of researchers and donators. Between these 3 groups of actors, there is a feedback loop connection between the government and the society, which implies that the government has created some programs based on the society characteristic. Meanwhile, the external actors only interact with the government towards coordination. The human-water interactions are different between the government and society, the government has a negative feedback loop with the water system, which means the government reduce what occurs in the water system, for example the high sediment in the system influences the government to remove the sediment. Surprisingly, it is not the case for the society, as it has a positive feedback loop especially regarding high sediments. Once the river had high sediments, people started to throw more garbage there thinking it would not be back clean, which would make the river even worse. The actions done by the government and society are not only influenced by the water system, but also other external factors. For the government, economic, socio-cultural and politic factors are very influential to their actions. On the other hand, economic and socio-cultural factors are very influential to the society actions. These external factors seem to be more influential than the water system itself for their actions towards the water system. Qualitative socio-hydrology study is clearly different with the quantitative study. Qualitative focuses on the why and how of relations in the system. It can give a good understanding on how such relations occur in the system. Hence, qualitative study can complement the quantitative study so that the model for quantitative study will not be oversimplified and based on valid reasoning.