Abstract:
he tank cascade system (TCS) is a particular ecosystem centred on a
series of artificial reservoirs where water flow is regulated from a smaller to larger
along the topography to control drought and flood. The system was constructed in
various ancient periods and has the potential to be used for managing the impacts of
climate change. However, the system is undergoing rapid degradation owing to the
present rapid environmental and social transformation. It is believed that the indige-
nous knowledge system of the Sinhala community was the driving force of the sus-
tainable existence of the system. Many TCS have undergone change including the
change in the demographic structure, particularly incorporation of Muslim commu-
nity settlements. Ranpathwila, a TCS in Anuradhapura, Sri Lanka, is one of them.
The question is how this assimilation affects the nature of the cascade system. The
study aimed to assess the effects of the demographic transformation on the sustaina-
bility of the Ranpathwila TCS by adopting qualitative data collection. Primary data
collection is based on (90) interviews, administered to capture all four reservoir-based
five settlements with key person interview methods, analysis of historical records and
text analysis methods and observations. It is evident from the analysis, that demo-
graphic assimilation, particularly the integration of Muslim settlements, has no con-
siderable negative effects on the cascade ecosystem. Further, there is an attitudinal
transformation from belief in supernatural powers to modernity parallel to the urban-
ization. It also noted that, this transformation is vitally important to safeguard social
harmony. There is a potential to sustainably maintain the system upon the strength of
the social harmony among different communities as narrated in the historical records.
The study recommends populating the study to capture broader spatial extent to test
the validity of the findings. Further, assess the system’s functions expand from tradi-
tional ones to modern functions such as expansion of fisheries and tourism sector.
