Page 345 - Proceedings book

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1. GIS-Based Spatial Mapping

High-resolution satellite imagery from Landsat 8 and Sentinel-2, along with digital
elevation models (DEMs) and topographic maps, were collected from the USGS Earth

Explorer and the Survey Department of Sri Lanka. Using ArcGIS Pro 3.1, key
hydraulic features such as ancient tanks, canals, bunds, and agricultural zones were

digitized and geo-referenced. These features were subsequently classified based on

their morphology, elevation, and catchment area. Hydrological modeling, including
watershed analysis and flow accumulation models, was conducted to assess the

connectivity between tanks and canals. Terrain analysis was also employed to
simulate runoff and water distribution patterns throughout the basin.

2. Ground Surveys and Environmental Archaeology
Field verification involved conducting ground surveys at 27 sites, encompassing

major tanks like Kala Wewa and various minor cascades in the upper catchment area.
During these surveys, structural remnants, bund heights, and canal gradients were

meticulously recorded. To infer paleoenvironmental conditions, core samples were
collected from desilted tank beds at selected locations for sediment analysis, focusing

on grain size, organic content, and depositional layers. Radiocarbon dating of organic

materials, such as charcoal and pollen, found within the sediment layers was
performed to establish a timeline of environmental change.

3. Analytical Framework

The spatial dataset generated through GIS mapping was analyzed thematically to

identify functional clusters of hydraulic elements. Archaeological findings were then
contextualized with historical records, including texts such as the Mahavamsa and

Chulavamsa, to develop a diachronic narrative of the ancient hydraulic systems.
Furthermore, content analysis was applied to descriptive and interpretive data, which

was coded to assess correlations between land-use changes and ecological degradation

over time.

Literature Review
Sri Lanka has historically been recognized as a cradle of hydraulic civilization in

South Asia, characterized by an extensive network of ancient irrigation systems that
transformed its dry zone into a fertile agricultural heartland. Among the numerous

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