Annual Water Yield - Water Demand Table: how to deal with urban LULC classes?

I runned a lot of times the Annual Water Yield and now I’m working on the Water Scarcity and Valuation components. I have some doubts of how much complexity for water consumption/LULC classes it is possible to consider. My reality is that beyond the consumption of water by urban population, also the natural drainage receives domestic sewage, leading to two basic impacts: 1) water produced in cities are not consumed, due to its quality, and 2) this water often reaches the reservoirs decreasing its quality, which can rise costs with treatments, as eutrophication per example. Those two points are not a direct consumption, but it affects water scarcity.

I was thinking how my Water Demand Table can reflect not only the water consumption but also this water scarcity that cities generate. Would it make sense?

I’m not a hydrologist, but it sounds like the InVEST Annual Water Yield model might not directly handle the specific cases that you’re looking for. It sounds like there are two aspects of your landscape that you’re trying to model:

  1. The availability of high-quality water for human consumption (including by the cities producing the sewage)
  2. The quality of water in the reservoir, given that there are upstream contaminants.

Does that sound right?

If so, I don’t think the Annual Water Yield model will help much with what you’re looking for. The Water Scarcity portion of the model could be thought of as “Realized Supply”: the difference between the amount of water produced by the landscape and the amount consumed, aggregated by watershed. So this would be a volume of water rather than a metric of quality.

Since you specifically mention eutrophication and the presence of sewage in waterways, maybe the InVEST Nutrient Delivery Ratio model, would be useful in your study?

Perhaps @swolny or @RafaSchmitt would have some additional guidance for how you might do this?