aerial view of the tidal mudflats in the eemsdelta, holland

eems eemsdelta nature fluvial drone anastomosing netherlands aerial dollart unesco levee dollard eemsmond delfzijl eemshaven sea gully groningen sanctuary wetland tide tidal sand mudflats landscape europe ebb creeks creek coastline branch fractal mudflat shape channel wild birds bierum watum termunten river delta geology meandering wallpaper