Supplementary information for: "Surface Water Quality Assessment of the Arkavathi Reservoir Catchment and Command Area, India, through Multivariate Analysis: A Study in Seasonal and Sub-Watershed Variations"

To analyse the surface water quality of the area, we begin by identifying the sub-watersheds using Survey of India (SOI) Topographic Maps of 1:50,000 scale – 57 H5, 57 H6, 57 H7, 57 H9, 57 H10, 57 H11. Based on the drainage features of the area, the study area is demarcated into six sub-watersheds. Drainage map, Geology map, Contour map, and Digital Elevation Model (DEM) map are prepared using RS and GIS. Once the sub-watersheds are demarcated, surface water samples within these sub-watersheds are collected for further analysis as explained in the sections below. 30 samples were collected over a study period of two years covering three prominent seasons of pre-monsoon, monsoon, and post-monsoon periods. These samples were then subjected to various physical, chemical, and bacteriological tests such as pH, temp., DO, BOD, etc. (Bureau of Indian Standards: Public Safety Standards of the Republic of India: Chemical: Environmental Protection and Waste Management) to ascertain its usage for domestic purposes as well as for agricultural activities.

为开展区域地表水水质分析，本研究首先采用比例尺1:50000的印度测量局（Survey of India, SOI）地形图图幅57 H5、57 H6、57 H7、57 H9、57 H10、57 H11进行子流域划分。基于研究区域的水系发育特征，将研究区划分为6个子流域。借助遥感（Remote Sensing, RS）与地理信息系统（Geographic Information System, GIS）技术，绘制了水系图、地质图、等高线图及数字高程模型（Digital Elevation Model, DEM）图。完成子流域划分后，采集各子流域内的地表水样本以开展后续分析，具体流程将在下文章节详述。本研究周期为两年，覆盖汛前、汛期及汛后三个典型季节，累计采集水样30组。随后对上述水样开展多项物理、化学及细菌学检测，包括pH值、温度、溶解氧（Dissolved Oxygen, DO）、生化需氧量（Biochemical Oxygen Demand, BOD）等，检测依据为印度标准局（Bureau of Indian Standards, BIS）发布的《印度共和国公共安全标准：化学：环境保护与废物管理》规范，以评估该地表水是否适用于生活饮用及农业生产活动。