Other communes along its length include: Selles, Brunembert, Bournonville, Alincthun, Crémarest, Wirwignes, Questrecques, Samer, Carly, Hesdigneul-lès-Boulogne, Isques, Saint-Léonard, Hesdin-l'Abbé, Condette, Saint-Étienne-au-Mont, and Outreau.

Just like its neighbour, the Wimereux, but unlike most Pas-de-Calais waterways, the Liane exhibits highly marked seasonal fluctuations.

High waters occur at the end of autumn and in winter, characterised by monthly mean flow rates between 3.06 and 5.33 m³/s, from November to March inclusive with a maximum in January.

Low waters occur in summer, from June to September, with a decrease in monthly mean flow rate descending to 0.76 m³/s in August.

Other than near its source, the Liane's water quality was mediocre to highly polluted during the years 1980–1990, mainly as a result of industrial and urban waste.

Towns and industries are now polluting less, but ploughing has conquered land from farming and pasture which have been pushed back in this region, and farmland erosion and fields which are kept barren in winter and autumn are a cause of the Liane's almost constant turbidity.