well, it’s complicated. Several parameters there dictate the need of water. Water availability times root depth gives you total water need. Allowed depletion reduces that amount to the amount we’re going to be working with. That range becomes 0-100%.
So in reality, with an allowed depletion of 25%, a 0% on the graph is really 75% on the larger all water need scale. 0% represents 100 - allowed depletion, 100% represents 100. Not sure how to explain this better. The allowed depletion % changes what the 0-100 range means. The water availability times root depth times allowed depletion gives the range of water between 0 and 100. A lower allowed depletion % means less water range, meaning a faster swing between 0% and 100%. A larger allowed depletion % means a slower variation between 0% and 100% because there is more water to juggle with