Slope Storage

Slope Power Reservoirs contain a portion of their Storage in the wedge created by the sloping water surface. The following user method calls to additional methods that perform the mass balance calculations in Slope Power Reservoirs for all dispatch methods.

None

This is the default method in the Slope Storage category. It performs no calculations and has no slots associated with it. An error is posted if this method is selected. The user is required to choose Storage Segments.

Storage Segments

The user has the option of dividing a reservoir into longitudinal segments. This is most useful for large reservoirs and relatively small timesteps, where the propagation of a change in flow takes more than one timestep to travel the length of the reservoir. Reservoir segments are numbered in the upstream direction, with the first segment being the farthest downstream.

Figure 24.3

The Storage Segments method does not perform any calculations. Instead, this method makes visible the new method category: Slope Storage Coefficients. You then have the option of selecting either the Impulse Response method or Weighting Coefficients method to calculate the segment storage.

The Storage Segments method requires you to specify the number of segments in the reservoir and provide the headwater, backwater, and storage relationships for the Segments in Reservoir that are used by the Slope Storage Coefficient methods to calculate segment storage. Also, you can specify the Segment Storage Adjustment based on the backwater elevation and change in backwater elevation.

See the following topics for details:

Slots Specific to This Method

Segments in Reservoir

Type: Table

Units: NONE

Description: Number of longitudinal segments in the reservoir

Information: Multiple segments are useful for large reservoirs and relatively small timesteps, where the propagation of a change in flow takes more than one timestep to travel the length of the reservoir. Reservoir segments are numbered in the upstream direction, with the first segment being the farthest downstream.

I/O: Required input

Links: Not linkable

Profile Storage Table

Type: Table

Units: LENGTH vs. LENGTH vs. VOLUME

Description: Total storage of each segment corresponding to a headwater and a backwater elevation

Information: 3‑D table containing data relating headwater and backwater elevations to segment storage. Each reservoir segment has its own three-column block of data. Data must be entered into these tables in a structured way in order for the three-dimensional table interpolator to work correctly. Headwater must be input in blocks of the same values, increasing down the table. For every headwater elevation block in column 1, backwater values should be listed in increasing order in column 2, with the corresponding segment storage in column 3. Following is a sample table for a one-segment reservoir.

Headwater | Backwater | Storage |
---|---|---|

500 | 500 | 800 |

500 | 510 | 805 |

500 | 520 | 810 |

550 | 550 | 900 |

550 | 560 | 905 |

550 | 570 | 910 |

600 | 600 | 1000 |

600 | 610 | 1010 |

600 | 620 | 1020 |

I/O: Required input

Links: Not linkable

Segment Storage

Type: Aggregate Series

Units: Volume

Description: This slot holds the storage in each segment of the reservoir. The total storage in the reservoir is equal to the sum of the segment storage (within convergence).

Information: There will be one column for each segment. The number of columns is automatically adjusted at run start.

I/O: Output only

Links: Not linkable

Segment Storage Adjustment

Type: Table Slot

Units: Length, Length Volume

Description: This 3‑D table will have one 3 column block for each segment in the reservoir. The first column of the block is the upstream elevation of the segment, the second column is the change in elevation from the previous timestep, and the third column is the storage adjustment factor.

Information: The table must have 1 block for each segment. This will be adjusted at run start. It can have NaNs at the bottom of the table. If there is no data in first row for a segment, then no adjustment will be applied to that segment.The correction can be either positive or negative. Following is a sample correction table. The correction for Segment 1 is not applied (that is, always zero), but Segment 2 does have a correction factor.

Segment 1 | Segment 2 | ||||
---|---|---|---|---|---|

Upstream Elevation 1 ft | Upstream Elevation Change 1 ft | Storage Adjustment 1 cfs-day | Upstream Elevation 2 ft | Upstream Elevation Change 2 ft | Storage Adjustment 2 cfs-day |

NaN | NaN | NaN | 550 | -4 | 10 |

NaN | NaN | NaN | 550 | -2 | 2 |

NaN | NaN | NaN | 550 | 0 | 0 |

NaN | NaN | NaN | 550 | 2 | -2 |

NaN | NaN | NaN | 550 | 4 | -11 |

NaN | NaN | NaN | 575 | -4 | 9 |

NaN | NaN | NaN | 575 | -2 | 2 |

NaN | NaN | NaN | 575 | 0 | 0 |

NaN | NaN | NaN | 575 | 2 | -3 |

NaN | NaN | NaN | 575 | 4 | -12 |

I/O: Input only.

Links: Not linkable.

Revised: 08/02/2021