Assessment of coastal aquaculture ponds in Asia with high resolution SAR data

Kurzfassung

Aquaculture is one of the fastest-growing animal food production sectors worldwide and is the main source of valuable animal protein in many countries. The farming of fish, crustaceans and mollusks generated income and employment for many people in rural coastal areas and has attracted considerable attention for its high export value and potentials in terms of protein supply and global food security. Rising demand for fish, crustaceans and mollusks, and international trade has driven the rapid expansion of the total global aquaculture production with an increase from 17.8 Mio tones in 1993 to 70.2 Mio tones in 2013. Farmed aquatic products account for 43 percent of the total volume of aquatic food produced in 2013 and it is foreseen that aquaculture will be the main source of aquatic animal food in human consumption since capture fisheries production stagnated over the past years. Asia alone generates nearly 90 percent of the total aquaculture production worldwide – and China is by far the largest producing country with a share of more than 65 percent of the global aquaculture production. Aquaculture has mainly been developed in valuable fertile environments along the coasts in Southeast Asian and East Asian countries and caused large-scale land use changes, destruction and loss of coastal wetlands and pollution of waters and soils. Quantitative assessment of the spatial extent and distribution of aquaculture is of utmost importance for a sustainable management of land and water resources. Such information can further be used to identify and investigate environmental impacts which might deserve special attention in terms of future human and ecosystem health. However, inventory data barely exists on national or regional level but is crucial to analyze current status and trends of aquaculture development around the globe. Here, earth observation can effectively support the planning and management of aquaculture practices and the implementation of adequate regulations and protection measures. In this presentation we address the potentials of radar data processing to map large-scale coastal aquaculture areas in Asia, highlighting the opportunities to delineate coastal pond structures using advanced SAR data. Radar instruments provide all-weather capabilities obtaining cloud-free imagery which increases capabilities to monitor and map aquaculture structures – such as ponds – and is therefore a promising data source for aquaculture research. As part of the established European Copernicus program, the Sentinel-1A C-band SAR satellite has been launched in 2014 imaging the earth’s surface at high spatial resolution for more than a year now. The free and open access data policy of the Sentinel fleet opens up new opportunities to process large-scale and timely data to analyze aquaculture on local, regional and even global scale. In our study, Sentinel-1A interferometric wide swath mode imagery is being used to test the capabilities of radar imagery to delineate aquaculture ponds in coastal test areas in China and Vietnam.