# FAQ / The water level is unnatural in the river given the HQ formula¶

When the river model was calculated, the results showed extremely different water levels in several cross-sections.

The water surface shape of the river is not smooth. This is an unnatural result.

Please tell me the cause and countermeasures.

## response¶

When I looked at the project, the water level was extremely different between the cross-section that gave the HQ formula and the cross-section that did not.
Can you take measures such as giving the HQ equation to all cross-sections, not giving the HQ equation to all cross-sections, or adjusting the HQ formula so that the result is close to the irregular flow calculation?

DioVISTA interpolates and interpolates river cross-sections in the following ways.

ITE !!! "Technical Reference/ River Models/ Properties"
River cross-sections are automatically interpolated to ensure that the maximum cross-section distance is not exceeded. Based on the cross-section adjacent to the upstream of the cross-section to be interpolated and the cross-section adjacent to the downstream, the distance marker, riverbed height, left bank top height, right bank top height, cross-sectional average roughness, and river width are obtained by linear interpolation. Similarly, the cross-sectional area and diameter depth values relative to the water depth are linearly interpolated for the values of two adjacent cross-sections. However, no HQ expression is generated. That is, the interpolated section does not have an HQ expression unless the user explicitly supplies an HQ expression.

In this case, [Maximum traverse distance (m)] was  set to . Of the 14 cross-sections, interpolated cross-sections are placed between 10 cross-sections, and the cross-sections do not have the HQ formula. As a result, the result was that the water level was extremely rising between the transverse lines, as you pointed out.

[River 1]If you set the property [Maximum traverse distance (m)] to for example  , you will get the desired river channel water level.

Since it is a river with a steep slope, I think it is a good idea not to use the HQ formula, or to interpolate the cross section and give the HQ formula that matches the cross-section.

Last update: 2023-03-20