Hello, I run the water yield successfully (ONLY THE “SUPPLY” SIDE), but somehow the water yield in urban areas is higher than in forests. To me this does not make much sense. Am I wrong?
If I am right, I think the only explanation I could find is given by the “root restricting layer depth”. I used the layer suggested (ISRIC) and I saw that depth to bedrock in urban areas is much deeper than in forest and other natural areas. Why? Would it make sense to correct this by masking built-up areas where root restricting layer is actually the very surface? Would this solve my problem?
If this is not the problem, then why am I getting higher values of water yield in urban areas compared to forest and other natural LULC? Or is this correct?
Thank you for your help!
Hi @matteoriva -
It is often the case that there is more runoff in urban areas, if they are paved and have little vegetation. Forests use a lot more water, so in simple models like Annual Water Yield, they usually produce less water yield, because more of the water is being evapotranspired.
When the model results appear to differ distinctly by land cover type, the first place to look is at the biophysical table, and see if those values explain the results. Soil depth data will obviously affect the results, but in the model it is used along with the rooting depth data (per land cover type) to calculate AWC.
Thank you for the reply. I think the results should be fine then. But I still don’t really understand how to interpret them and how to link them to water demand. What does this water yield tells me? And how does this relate to water demand?