Why is water displacement an effective way of measuring the volume of an irregular solid?

Water displamement is effective because there is no way to get an exact and accurate measurement of an irregular solid because you can't measure curved line. Water displamement gives you a proper, exact, and accurate answer.

As it is known that volume of an irregular object cannot be measured because we cannot measure the volume of a curve.

As a result, if we immerse an irregular solid object into a beaker or container filled with water then the volume of water displaced by the object will be equal to the volume of object itself.

Hence, we get to know the volume of irregular solid object by doing so that is why, water displacement is an effective way of measuring the volume of an irregular solid.