This Map was provided by the Environment Agency direct to Your Mirfield.
What does mAOD mean “above ordnance datum” Weirs are commonly used to control the flow rates of rivers during periods of high discharge? Sluice gates (or in some cases the height of the weir crest) can be altered to increase or decrease the volume of water flowing downstream.
The name ‘Calder’ is thought to come from the early Common Brittoic meaning ‘hard or violent water’ (the modern Welsh word for hard is (caled) or possibly from another Celtic language, meaning river of stones. This history is reflected in the name of a village, Walsden, just inside the border of upper Calderdale, which is probably derived from Wales Dene, or “Valley of the “Welsh” (foreigners)” in Anglo-Saxon.
The river rises approximately 1,300 feet (400 m) above sea level