Rivers

Look across a typical dale from a moor-edge viewpoint and the course of the beck in the dale bottom is only given away by the twisting line of alder trees hugging its banks. Go down into the dale and find a bridge or a footpath along the bank alongside and you might be lucky enough to spot a dipper, a small brown bird with its bright white bib, sitting on a rock above the water, or a bright blue flash as a kingfisher flies by.

The rivers in the North York Moors have an amazing range of characters: small becks babbling over moorland, swollen torrents thundering through deep wooded gorges, and slow waters quietly meandering through flat valleys. Most of the rivers flow over stones and gravel through firm tree-lined banks. In some places the rivers lie low between soft sandy easily eroded banks and clay that slowly but steadily slips into the water. These characters are a result of the surrounding geology, landform and land-use.

The character can change dramatically depending on rainfall. Sections of river in the south of the Park can "dry up" in dry spells, disappearing through "swallow holes" in the limestone. Clear shallow water can soon turn to murky brown torrents. The Esk can rise to flood levels as it did in October/November 2000 flooding houses and sweeping away fences trees, even whole sections of stone walls. In 1930/31 the Esk flood was so great it swept away many of the road and rail bridges in the valley. Tributaries of the River Derwent can flood equally dramatically, notably in the Hawnby area in June 2005.

There are two main river catchments in the Park either side of the central moorland watershed: The Esk catchment in the north and the upper tributaries of the Derwent catchment on the south. The becks on the western edge run into the Swale catchment, small becks along the east coast run straight out to the North Sea and the Leven in the northwest runs into the Tees.