Does pollarding a Poplar tree increase the demand for water?

Weird question - exam? Doyou mean does the tree take more water?

Tree roots take up water which is transpired out through the leaves. Pollarding = cutting off lots of branches and leaves so the tree has a lot fewer leaves. So does it need more water or less?

at first it wont haveso much to takewater to which is basic maths thow just for the record i cant think of a less usefull tree to pollard as its beauty is its tall slim imposing size . i have a huge pair about 100 foot away from my house and there are some serio0s roots all the way to my path some bigger than footballs and there not egsactly slow growing . anyway as the tree starts growing fast to make up for its loss then you will have some more watering to do but i wouldnt worry to much .often cuttings are cut right back so the roots get all the goodness and its not wasted on a few branches or leaves depending on the cutting ofcourse .like bamboo im interested to know why you are pollarding the tree and why your worried about its water intake . if its well estableshed its tap root is more than likley well bellow the water table meaning it wont matter to you as such unless its near your house then the only option is to cut it down . as weeping willows you can take cuttings in winter very early spring while there dorement and plant and water well . come sumnmer you will have a new one . also you will find it will fire up suckers that apear somewear along there roots . they are the farmers faverite because they are tall, quick growing and dont actualy have a very big footprint like say a laylandii .