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Hydrologic Analysis

Hydrologic analysis establishes the runoff-quality, recharge, and runoff-quantity inputs that every later design decision depends on. In the live source set, this stage is less about memorizing a single formula and more about keeping the governing standards separate and documented.

Structured citation evidence for this page lives in the sibling claim manifest.

What This Stage Produces

The enrolled source set supports a hydrologic workflow that produces:

  • the Water Quality Design Storm target for runoff-quality design
  • the recharge comparison needed where groundwater recharge is part of the project standard
  • the peak-rate benchmarks for runoff quantity control
  • the inputs needed for any 2026 volumetric-reduction demonstration

Standard-by-Standard Inputs

Standard lane Governing source anchor Output needed later
Runoff quality N.J.A.C. 7:8-5.5(d) Water Quality Design Storm target and any TSS-treatment framing
Groundwater recharge N.J.A.C. 7:8-5.4 and 7:8-5.7 Recharge comparison using the correct pre-construction assumptions
Runoff quantity N.J.A.C. 7:8-5.6(b) 2-, 10-, and 100-year comparison inputs and peak-rate benchmarks
Volumetric reduction N.J.A.C. 7:8-5.6(d) and Chapter 14 Retention-path inputs for the 2026 compliance check

Source-Backed Framing

Three points matter most at this stage:

  1. The Water Quality Design Storm does not change just because the project later uses a GI retention pathway.
  2. The recharge standard carries its own pre-construction land-cover assumptions and cannot be reduced to a generic impervious-only shortcut.
  3. The runoff-quantity standard remains tied to the rule's design storms and pre-construction comparison framework.

Why the Inputs Need to Stay Separate

The source-backed pages downstream depend on different parts of this analysis:

  • BMP selection needs to know whether infiltration-based strategies are even plausible
  • BMP sizing needs the runoff-quality, recharge, quantity, and volumetric-reduction inputs separately
  • maintenance planning depends on the chosen BMP configuration, which in turn depends on this hydrologic baseline

The main recovery point from the older workflow copy is that one spreadsheet or one runoff-volume number does not stand in for the entire stage.

That is why the hydrologic stage is a shared input layer for the whole workflow rather than a single runoff-volume calculation.