Using Pléiades data to understand and monitor a dynamic socio-ecological system: China's Poyang Lake

Abstract

Poyang Lake, the largestfresh water reserve in China, is a monsoon lake characterized by large water surface variations between the dry season, November to March, and the wet season, June to September. This extreme variation and its amplitude overtime have a number of implications forthe system in terms of water resources, public health (bilharzia/Schistosomiasis), and also in terms of b iodiversity. Poyang's dynamic intra- and inter-annual surface variation is difficult to qualify and to understand using established remotely sensed data techniques and methods. The hydrological dynamism on shorttemporal scales that Poyang exhibits requires relatively high frequency of monitoring to be effective. Within the Pléiades Users Thematic Commissioning phase (RTU) framework, monthly acquisitions were programmed for 2013 covering the most biodiverse and sensitive part of the lake's oldest protected area: Poyang Lake National Nature Reserve (PLNR). These Pléiades data have been used to precisely delineate waterways, document infilling and draining patterns, and to map vegetation based on 14 transects. Finally, this work has looked at human activity impacts on the environment such as the documenting of the establishment of arable farming on National Park borders, sand extraction impacts on waterways, and mapping fish traps in the region. Plus, two stereo triplets have been acquired allowing producing very precise and detailed Digital Elevation Model (DEM). The results obtained using Pléiades imagery have been transferred to PLNR administration and to the International Crane Foundation, demonstrating the benefits that Pléiades data bring to environmental monitoring. Pléiades imagery and time series offer new opportunities to understand dynamic socio-ecological systems and provide managers and conservationists with novel tools for the administration and conservation of ecosystem function.