Effective porosity

Imagine you have a sponge. You can see that the sponge has tiny holes in it, right? These holes are like the spaces between the grains of soil or rocks.

Now, when you pour water on the sponge, the water goes into these tiny holes and fills them up. This is like when water goes into the spaces between soil or rock grains.

But, here comes the tricky part. Not all the holes in the sponge are able to hold water. Some of them may be blocked or too small. So, even though the sponge has holes, not all of them can hold water.

This is why we need to measure the effective porosity of soil or rocks. Effective porosity is like counting how many holes in the sponge can hold water, and then figuring out what percentage of the whole sponge that is.

So effective porosity tells us how much water a soil or rock can hold in its tiny little spaces where water can go, and it helps us figure out how much water will be available for plants or animals to use.