## Starting point (origin) of the pier

Defining the origin point initiates the definition of the vertical profile of the pier. Then, linear segments, arcs of circles or polynomials are used to define the vertical profile segments. The procedure terminates by choosing the end arrival point.

To choose the starting point, the Upstream Starting Point command in the Spillway Pier window is triggered. The resulting window is shown in Figure 46. The upstream starting point is defined as the origin point on the foundation or chute that is in contact with the pier. In the event the origin point of the chute does not coincide with the upstream point on the foundation, the starting point of the pier must be on the upstream foundation point. If this is the case, the origin point of the pier must be on the perimeter of the chute. The user can use the available buttons to calculate the Y value based on a specified X value and vice versa. When this window is closed, the pier definition window is updated, and the position of the origin point is indicated with a cross.

Figure 46