REMOTELY SENSED DATASETS FOR MAPPING FLOOD CHARACTERISTICSAND WETLANDS OF THE TONLE SAP BASIN, CAMBODIA

摘要

This paper outlines how spatial information technologies might be more effectively incorporatedinto operational programs for flood management and mitigation and be used for the observationof wetland environments. The Tonle Sap Basin in Cambodia and the Mekong River Region arechosen as examples to demonstrate how remote sensing can facilitate the immediate needs offorecasting and monitoring flood discharge behaviour as well as enhancing flood modellingcapabilities and land cover mapping.Crucial to the successful implementation of flood mapping and monitoring techniques is theneed to acquire near real-time optical and radar data and to manage its 'seamless' incorporationinto relational databases. In addition, reliable information on land cover, land cover changederived from the same source, especially over populated floodplain areas, can be a beneficialinput to the development and implementation of integrated floodplain planning and managementstrategies.The paper describes the potential for using integrated satellite observations to meet the needs offlood mapping and monitoring programs including real-time MODIS data reception and itssystematic incorporation into basin-wide monitoring programs; the use of RADARSAT,ENVISAT and ALOS PALSAR (from mid 2004) to complement, validate and replace MODISfor flood mapping and monitoring activities during periods of cloud cover, and the generation ofaccurate and highly detailed digital elevation models (DEM's) from SRTM for use indetermining topographic height and slope, drainage pattern configuration and volume runoff.Also, the use of time-series satellite radar altimetry (TOPEX Poseidon and Jason-1) formonitoring river and flood levels is discussed. Measurements of staging height over large areassuch as The Tonle Sap Great Lake and along major tributary rivers permit forward modelling ofabove-average flood events and the identification of cultivated lands and populated areas likelyto be impacted by high magnitude flood events. Future measurements from Jason-1 will allownear real-time observations and have centimetre accuracy relevant to a fixed datum.