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There are several broad components to the research, under the auspices of which numerous specific research projects are conducted: Macro-organisation and operation of the water management infrastructure:The scale of the network is such that, in order to select key test sites for rigorous analysis, a comprehensive map of the network in its geographical context, the arrangement of its components over space, and a hydrological model of the system is required. Building on our previous work, we will exploit a new aerial radar survey (GeoSAR) that permits penetration of the vegetation canopy, providing images of subsurface flow features - such as infilled canals - that were not visible in the earlier radar survey. The ultralight plane, whose deployment has been tested over the past several years, will be used to systematically survey and digitally record all the major canals of the water management network and the great embankments. This has already proved invaluable as a practical and efficient way of surveying for roads and to complete the ground-truthing required to prepare maps from the radar images. These low level aerial surveys will be complimented by ground truthing and, in selected locations, sub-surface geophysical survey. Analysis of key components of the water management infrastructure:Hydrodynamics specify that the effects of water movement propagate downstream. For example, erosion at the head of a canal leads ipso facto to deposition somewhere downstream – where and in what form is specifically informative about how the canal was functioning. Therefore, in order to properly track this interdependence, we will select key sub-catchments within the network, each of which represent a successive addition to the network over time, and select key sites down the length of the primary canal in each sub-catchment. The key locations for studying the operation and the breakdown of the network are the junctions between different catchments, as their stratigraphies above and below the junctions are critical to understanding how the flow rates were changed at the switch points. These locations are especially important where the rivers have broken out of the Angkorean alignment of canals and embankments (predominantly N-S and E-W) to revert to the natural NE-SW direction of water flow across the plain. The history of network is built into the embankments and deposited in the canals. The form of the deposits in and adjacent to the banks tells us how they were built and what effects they would have had on the surrounding landscape. The occupation debris, such as ceramics in the banks, must postdate the construction, as must any fire-pits in them with dateable charcoal. The deposits in the canals derive partially from the erosion of the embankments and so partially mirror the debris piling up on the banks. Palaeo-environment:It is necessary to link our analysis of the operation of the water management infrastructure to a framework of ecological and environmental change contemporary with the growth and collapse of each sub-system. Vertical profiles of sediment (drill cores) representing a time transgressive sequence will be analysed for pollen content and directly dated using high-precision small-sample radiocarbon dating techniques using carbon within the pollen grains themselves. Palynology is a powerful tool in reconstructing past land cover and has the capability to identify deforestation, land-use types and intensity, and land abandonment and reafforestation. These data will permit a reconstruction of the extent of deforestation and the type and intensity of land use associated with the 'roll-out' of the water management infrastructure. |
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Written by Dan Penny on Friday, 24 June 2005. Last Updated by Damian Evans on Wednesday, 14 September 2005 |