bank blue canada current curved evening flow forest light mountain natural nature river shadow shallows shore tree water cumbria England english Great Britain small sunlight view banks brown green hills pastoral rural sediment trees wales welsh aggressive Australian birds cascading chroicocephalus-novaehollandiae city colors colours common cool cooling edge edges edging flowing fountain gray-and-white grey-and-white gulls Larus-novaehollandiae levels multi-level Noisy prolific reflecting ripples rippling scavengers screeching seabirds seagulls silver-gull splashing standing wading waiting watching waterbirds cliff drop gorge landscape rock summer woodland aerate aeration air control dam management pour stone stream Sussex wall weir background beach clear flush pebbles sand sandy sea splash texture wash wavelets waves whitewater