### Manual Input

- When users choose
**Unknown**as the shape and**Manual Input**as discharge type, users need to give the table of Discharge-Storage Curve (**Rating Curve**).

It has pairs of discharge-storage values to describe the Discharge-Storage relationship of the reservoir (m³/s vs ha.m or ft³/s vs ac.ft). A maximum of 20 co-ordinates can be entered. The first set of co-ordinates must be 0,0. If the outlet to the pond is not at the bottom of the facility, the curve can have multiple 0 values for discharge as shown in the example below. In this example the reservoir would fill up to a volume of 0.100 ha-m before discharging any run-off.

- When users choose a particular shape (
**Truncated Triangular Pyramid**,**Truncated Rectangular Pyramid**,**Truncated Wedge**,**Truncated Cone**, or**Elliptical Paraboloid**) and uses**Manual Input**as discharge type, users need to give the table of**Height-Flow Curve**. Then, the software will calculate the**Rating Curve**table, where the discharge is read from the**Height-Flow Curve**and the storage volume at each height is calculated based on the shape parameters.

### Discharge Type – Orifice

There are 2 types of **Orifice** to choose: **Bottom** and **Side**. Users also need to give **Area** and **Height** of the **Unknown** shape of reservoir. Based on the parameters of reservoir shape and orifice, the software calculates the **Rating Curve** table, where at different height of the shape the volume is calculated by using shape parameters and the discharge flow rate is calculated by orifice equations. Note: when the **Shape** is **Unknown**, the constant horizontal area is used for the shape volume calculation.

**Bottom Orifice**:

where, *Co* is the orifice discharge coefficient, *O_Area* is the orifice area, *g* is the gravity constant, and is the height above the bottom of the reservoir.

**Side Orifice**:

- When the is not above
**Bottom Elev. Offset**(i.e. the distance from the bottom of the side orifice to the bottom of the reservoir), the flow is 0. - When the is above
**Bottom Elev. Offset**but does not exceed the side orifice crown:

where*BottomElevOffset*is the Bottom Elev. Offset,*O_Height*is the orifice height,*Co*is the orifice discharge coefficient,*O_Area*is the orifice area,*g*is the gravity constant, and is the height above the bottom of the reservoir. - When the is above the side orifice crown:

where*BottomElevOffset*is the Bottom Elev. Offset,*O_Height*is the orifice height,*Co*is the orifice discharge coefficient,*O_Area*is the orifice area,*g*is the gravity constant, and is the height above the bottom of the reservoir.

### Discharge Type – Weir

Users need to give **Area** and **Height** of the **Unknown** shape of reservoir, when discharge type is **Weir**. Based on the parameters of reservoir shape and weir, the software calculates the **Rating Curve** table, where at different height of the shape the volume is calculated by using shape parameters and the discharge flow rate is calculated by weir equations. Note: when the **Shape** is **Unknown**, the constant horizontal area is used for the shape volume calculation.

**Rectangular Weir**

- When the is not above the weir bottom (i.e. <= reservoir height – weir height), the flow is 0.
- When the is above the weir bottom:

where*W_Width*is the weir width,*W_Height*is the weir height,*Cw*is the weir discharge coefficient,*R_Height*is the reservoir height, and is the height above the bottom of the reservoir.

**Triangular Weir**

- When the is not above the weir bottom (i.e. <= reservoir height – weir height), the flow is 0.
- When the is above the weir bottom:

where*W_Slope*is the weir slope,*W_Height*is the weir height,*Cw*is the weir discharge coefficient,*R_Height*is the reservoir height, and is the height above the bottom of the reservoir.

**Trapezoidal Weir**

- When the is not above the weir bottom (i.e. <= reservoir height – weir height), the flow is 0.
- When the is above the weir bottom:

where*W_Slope*is the weir slope,*W_Width*is the weir width,*W_Height*is the weir height,*Cwr*is the weir discharge coefficient for the rectangular part,*Cwt*is the weir discharge coefficient for the triangular part,*R_Height*is the reservoir height, and is the height above the bottom of the reservoir.