Dear all,
I am curious about the positive and negative values when plotting the evapotranspiration and percolation graphs.
Regarding the evapotranspiration graph, does a negative value mean water leaving the soil surface? (Based on the rainfall graph, which displays positive values, indicating water intake from rainfall into the soil.)
Concerning the percolation graph, does a negative value indicate water moving through the soil to deeper layers? In other words, does a negative value mean water exiting the soil at the selected cross-section for the graph and entering the underlying soil layer? Is my understanding correct?
I would greatly appreciate any comments or insights to confirm my understanding.
Thank you in advance for all of the comments.
When water enters an element, the water flow/flux value is positive. Conversely when water leaves an element, the flow/flux value is negative. Thus, rainfall values are considered positive water flow values, as you have noted.
When plotting the results at surface nodes, if the reported infiltration water flux is negative, water is actually leaving the domain according to the computed water balance. For more information on the water balance associated with the Land-Climate Interface boundary condition, please see this video: Land Climate Interaction Analysis with SEEP/W - Videos (seequent.com)
Thank you for your response. I genuinely appreciate the insights you have shared; they have been incredibly helpful in deepening my understanding of this matter.