Water Resources Surface Water Software: Full Equations (FEQ) Model Web Resources
These notices are superseded by the release.txt distributed with the subsequent released versions of FEQ. User notices and bug reports (if any) for subsequent releases of FEQ and FEQUTL may also apply to this version.
An error has been discovered in reporting the time step when using a diffuse time-series file (DTSF) with a starting time other than 0.0. The reported time offset depends on the initial hour of each event. If the starting hour is zero then the offset is zero. Otherwise the offset depends on the starting hour. If the starting hour is 1, then the offset is 1 - 1/24.0 hours, which is slightly less than one hour. Thus the maximum offset in the reported time is one hour or less. It appears that this discrepancy has been present for some time. To prevent this bug, use a starting time of 0.0 when using a DTSF, or use a version later than 10.25.
There is a bug in reporting the interpolation for high-water marks. The stationing factor is not applied to the output when interpolating. Thus small errors on the order of a few tenths of foot are possible. This is relevant only for users who utilize the file hwmark.loc containing the observed high-water marks for their model.
Uninitialized variables were discovered that could have the following possible effects for versions prior to Version 5.80. (1) Sinuosity values were not being set properly for SEWER, MULPIPES, and MULCON. This would have had no effect because they were not used in the computations. FEQUTL always disables sinuosity corrections in closed conduits. However, the variables involved have been initialized to prevent future potential problems. (2) A bug was found in setting the line-segment Manning's n values in MULCON. One or two line segments could get a Manning's n at one point, that is for one line segment, that came from an adjacent conduit. Thus, if the conduits in the system had differing Manning's n, the near flowing full values of conveyance would be affected. In one test case the changes in conveyance were about 0.4 percent when flowing full. However, this was a test case in which the conduit diameters varied by more than a factor of two. Normally this would not be the case. (3) The CULVERT command had two cases of un-initialized variables. One involved using a type 1 value when type 1 flow was not possible. When corrected, the same results were obtained for the flows in the culvert. However, there might have been some cases where this was not true. The other involved a type 5 flow submergence-limit computation and the starting value for an iterative solution was not set. However, after setting it to a proper value, the same results were obtained as before.
A bug was detected in an area increment by the output routine in FEQUTL for versions prior to 5.66. The problem was eventually traced to the routine that removes duplicate elevations and near duplicate elevations from the list of breakpoints in top-width variation for a cross section. Detection of near duplicates was not properly scaled when the elevations were in the range of 700's or more. Thus, one or more breakpoints at the end of boundary line segments that deviated only slightly from horizontal were deleted from the list, because single-precision floating point had been used rather than double-precision floating point. This would cause a breakpoint to be skipped that should have been included in the table. The top widths and areas given in the final table were correct, but some increments in area and related elements were incorrect because a breakpoint was improperly left out.