Excel Hydraulic Flood Routing Calculation -- 2

I need a flood-routing solution built straight inside my existing Excel workbook. All the raw data are already there—the flow-elevation curve for the spillway, the volume-elevation curve for the dam, and an inflow hydrogram corresponding to the 1 000-year return period. The calculation is already started, I am having difficulties applying the curves and having the final graph showing inflow and outflow of the dam. Rules of the routing by the dam will also be attached to this file and need to be respected. I will also attach a graph of what my graph in the calculation should look like at the end.

Please apply a hydraulic routing approach. I want every step of the computation to live in Excel so the formulas, links, and any VBA macros remain transparent and editable by me later on; no external packages such as HEC-RAS or SWMM.

Key outcomes I am after
• Time-step reservoir routing that respects the storage–discharge relationships provided
• Outflow and water-surface elevation hydrographs for the entire event
• Clear documentation in-cell or on a separate sheet that shows the governing equations and any assumptions you make

If you can hand over a clean, well-annotated spreadsheet that reproduces the full routing for T = 1000 and lets me test other inflow files in the future, we are set.