Mapping coastal aquaculture ponds in Asian hotspots with high spatial resolution Sentinel-1A/B SAR data

Kurzfassung

Aquaculture is one of the fastest-growing animal food production sectors worldwide, the main protein source in many countries and offers great potential for global food security. While capture fisheries production stagnated over the past years, aquaculture is already contributing nearly half of the total volume of aquatic foods in human consumption today. Rising demand and international trade has driven the rapid expansion of aquaculture with a remarkably increase from 20 Mio tones in 1994 to 74 Mio tones produced in 2014. Asia alone generates 90 percent of the total global aquaculture volume which is mainly produced by pond systems in fertile coastal environments. On the other hand, the development of aquaculture has often led to large-scale land use change, destruction and loss of coastal wetlands, and pollution of waters and soils. We present an earth observation based approach to detect aquaculture ponds in study sites along the coast of China and Vietnam. The great advantage of active microwave instruments for aquaculture mapping is their all-weather, day and night capabilities which applies particularly for cloud-prone coastal areas. Topographic information derived from DEM data and coastline proximity were used to identify potential aquaculture areas. High spatial resolution time series of the free and open data acquired by the European Sentinel-1A and Sentinel-1B radar satellites were collected and processed to obtain temporally filtered images. Segmentation was applied to the filtered data to extract image objects and its features such as shape and size. The different backscatter response of the pond components (dikes and enclosed water surface) and its distinct rectangular structure allow for separation of aquaculture areas from other natural water bodies. Mapping of aquaculture ponds can effectively support sustainable development in the coastal zone and help to protect its valuable ecosystems.