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scworland / restore-2018

scripts for predicting streamflow characteristics in ungaged basins for RESTORE
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Relation between tot_basin_area and contributing drainage area from NWIS #17

Open ghost opened 6 years ago

ghost commented 6 years ago

Relation between tot_basin_area and contributing drainage area sourced from NWIS. This figure suggests from "difficulties" shall we say with one or the other areas. I know in Texas, we can have some contributing drainage areas (CDA) considerably less than total area. You see many sites plotting on the 1:1 line, and many cases of total area being larger. However, there are a number of orders of magnitude outliers, it seems. In Texas because of large noncontributing areas, the idea of contributing area is why I look and have used it in previous studies.

junk Relation in linear-linear space between the minimum of drain_area_va and contrib_drain_area_va fields from NWIS (horizontal axis) via W.H. Asquith and the tot_basin_area from HUC-NHD+ (vertical axis) via S.C. Worland processing and equal value line superimposed.

junk2 Relation in log10-log10 space between the minimum of drain_area_va and contrib_drain_area_va fields from NWIS (horizontal axis) via W.H. Asquith and the tot_basin_area from HUC-NHD+ (vertical axis) via S.C. Worland processing and equal value line superimposed.

scworland commented 6 years ago

I am not sure what the differences are between the two plots (obviously they look different but what do each represent?). I am not sure the exact reason for the differences. Can we get something similar to CDA for the hucs? We currently have tot_basin_area for all hucs and gages so we can make the predictions for the ungaged locations later.

ghost commented 6 years ago

I updated the original posting.

scworland commented 6 years ago

Okay, thanks. The tot_basin_area is based off of NHD+ catchments. How is the CDA derived?

ghost commented 6 years ago

Long story. Short is back in the day, stacks of 1:24k or so toposheet had HAND DRAWN delineation. There used to be an official drainage area stack/archive in each Water Science Center. (That was my understanding, but I physically held stacks of such sheets in Texas circa 1995.) These were used for planimeter computation and added up. From which both total area and contributing were tracked.

Later ArcHydro + DEMs came along and some level of digital computation was made as new streamgages came about. I remain very dubious of automated basin characteristic processing (mostly slope concerns---ask me another time). The Texas archive got either destroyed to lost to National Archives. It is of great interest to many stakeholders to get those recovered because we have major differences like I have shown your for the RESTORE footprint in which arguments over the area potentially influence stakeholder issues.