Hydro v6.1.1-beta Precipitation values differ between preloaded weather & equivalent raw NCDC data

Issues related to i-Tree v6.x can be posted in this section. 6.x updates and known issues will be posted here also.
Post Reply
rcoville
i-Tree Team
Posts: 52
Joined: Fri May 08, 2015 9:29 am
Location: Syracuse, NY

Hydro v6.1.1-beta Precipitation values differ between preloaded weather & equivalent raw NCDC data

Post by rcoville » Tue May 29, 2018 1:01 pm

We notice that in a few test cases, in Hydro v6 preloaded weather data differs slightly from equivalent raw weather data users obtain on their own. This bug only affects the weather data input and the rest of the estimates continue working fine with either source of weather data.

Given i-Tree Hydro is a first-order model generally used for qualitative estimates, not for predicting exact amounts of streamflow, the minor change in precipitation is a nonissue for most projects. Even in more quantitative projects that are calibrated to local streamflow, we've found that the nearest available NCDC data can differ slightly from hyperlocal meteorological stations. In that sense, slight differences in precipitation are expected and are inherently part of model uncertainty. Nonetheless, we intend to resolve this issue so that preloaded weather data and equivalent raw weather data match as expected.

For example, weather data for the DC sample project in Hydro v5 and the original v6 sample project files has ~780mm of precipitation, but downloading weather data from the map in Hydro v6.1.1-beta has ~930mm of precipitation for the same location & period. Weather Underground has actual precipitation for that location and period as ~870mm, so neither source is far off.

This bug is on our to-do list to fix and will be resolved in a future update.
A member of the i-Tree Team

Please provide feedback on our technical support services by clicking here to take our 5 minute survey
Post Reply