Identification of riverine, transition and lacustrine water zones based on water quality parameters in the Jatigede Reservoir, Sumedang, West Java

Jatigede Reservoir is an artificial reservoir formed by damming the Cimanuk River upstream, with a surface area of approximately 41.12 km² and an effective water holding capacity of 876.9 million m³. Horizontally, the reservoir is generally divided into three main zones: the riverine zone, the transition zone, and the lake zone. Sampling stations were selected based on the estimated spatial distribution of these zones within the reservoir. The purpose of this study was to classify stations into their respective zones through cluster analysis utilizing water quality parameters, which allows grouping of stations based on statistical similarities in environmental characteristics and quantify water volume and area for each zone. Cluster analysis is a multivariate statistical technique used to group sampling sites into distinct clusters according to the degree of similarity among measured variables. Based on the similarity analysis, stations with similarity values greater than 70% were grouped into three large clusters. Stations 1 and 2 represent the river zone; Stations 3, 4, and 5 correspond to the transition zone; and Stations 6, 7, and 8 represent the lacustrine reservoir zone. When viewed from the 12 parameters, only the depth parameter has a significant influence on each reservoir water zone. The riverine zone covers an area of 1.79 km² with an estimated water volume of approximately 19.56 million m³; the transition zone spans 15.09 km² with a volume of 234.72 million m³; while the lacustrine zone is the largest, covering 25.26 km² and holding 725.71 million m³ of water. These findings provide a comprehensive understanding of horizontal zoning in the Jatigede Reservoir, which is an important basis for ecosystem-based water resource management and aquatic ecological assessment.