Line 208 in abcd.py gives NAN values

[zarrarkhan]

Reported by Guta W Abeshu in email to Mohamad on Saturday, August 15, 2020:

"I found a numerical issue that results in NAN in estimated runoff magnitudes in the recent version of Xanthos. This issue is only noticeable beyond 1985 in many basins.

Below here is the equation used for ET opportunity computation (Line 208, on the GitHub file abcd.py). The NAN values were detected when the term under the square root is < 0. In terms of magnitude, the values under square root during these times were found to be in the order of 1e-10. So, merely rounding the decimal places reduces them to zero and solves the problem. It is a small issue, but the NAN values generated here propagates to flow routing, causing additional problems. "