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Showing posts from March, 2019

Evaluate the stream networks from watershed delineation

Recently I asked a question on the GIS Exchange site:
https://gis.stackexchange.com/questions/315910/quantitatively-evaluating-quality-of-watershed-delineation-stream-line-results

I also asked the question on Research Gate:
https://www.researchgate.net/post/How_to_quantitatively_evaluate_the_quality_of_the_watershed_delineation_stream_line_results

The reason is that we have developed a watershed delineation model and we need to evaluate whether our model performs better or not than the previous method.

So we set out trying to find ways to evaluate the results.
The first thing as a watershed hydrologist will usually do is to look at the stream segments. If they match up with actual stream lines then it means the model is not bad.

However, both our method and the previous method can produce similar stream segment results. The the question is how can we say which one is better than the other one.

So we did some research online, and most publications used visual results as proof. Basically,…

SWAT-MODFLOW stream flow routing problem

Surface water hydrology and groundwater hydrology are coupled together in natural ecosystem. While it is easy to say so, it is not easy to model both of them simultaneously.
In my earlier posts I have covered a lot on related topics including MODFLOW, PRMS and GSFLOW.
For example:  https://www.changliao.us/2018/03/paper-discussion-002.html https://www.changliao.us/2018/03/paper-discussion-001.html https://www.changliao.us/2015/09/integrated-groundwater-and-surface-water-01.html https://www.changliao.us/2016/04/surface-water-hydrology-modeling-002.html
Today I will discuss some other issues related to SWAT-MODFLOW. SWAT is another widely used surface hydrology model and there are ongoing efforts trying the couple MODFLOW with SWAT. https://swat.tamu.edu/software/swat-modflow/
Unlike PRMS, SWAT in general does NOT use grid based approach to run simulation. Instead, SWAT uses subbasin and HRU to represent the watershed. And this difference may cause a list of challenge for us. I will discus…