The Advanced Hydraulic City Structure of the Royal City of Angkor Thom and Vicinity Revealed through a High-Resolution Red Relief Image Map

Abstract

Numerical topographic data acquired through airborne laser scanning (LiDAR) performed at the Angkor Archaeological Park in Cambodia in April 2012 has revealed a large number of heretofore obscured water channels and ponds (Evans et al., 2013). Using this data, a high-resolution red relief image map (RRIM) was created of areas inside and outside the moated royal capital of Angkor Thom built during the latter half of the 12th century. The land around Angkor Thom is extensively covered by tropical jungle which has relatively well preserved the original urban structures and middle/post-Angkorian period modifications and renovations by escaping human-induced surface alteration except for the tourism-related infrastructure and renovations from the 20th century onward. The RRIM provided a new visualization method of localizing, minute topographical changes in regions with large undulations over a wide area. It has proved to be effective in mapping, on a single wide-area map, the numerous buried remains that exist as comparable height differences or minute undulations measuring less than 1 meter in height, and provides a unique aerial view of their widespread distribution. Based on the RRIM map, past archaeological studies were referenced to reconstruct the layout of the water channel network system. Past studies revealed that a large number of ponds had been dug inside Angkor Thom. The RRIM expanded the investigation and revealed the existence of many ponds outside the royal capital indicating that a residential community had flourished outside the moat-surrounded capital city. This paper was discussed the functional aspects of the water channel network and ponds that utilized the gentle gradient of the natural land to overcome the climatic induced environmental changes that were characterized by an extreme divide between the rainy and dry seasons.