{
 "tool": "pre-post",
 "toolVersion": "1.0.0",
 "methods": [
  "nrcs 1.1.0",
  "rational 1.0.0",
  "prepost 1.0.0"
 ],
 "commit": "ab22876",
 "date": "2026-11-04",
 "summary": "14 of 14 cases (75 values) within tolerance against NRCS TR-55 (1986), FHWA HEC-22 4th ed., Hand calculation of the published equation.",
 "note": "Generated by _workspace/tools/hh_verification.mjs from the fixtures; commit = code verified.",
 "cases": [
  {
   "id": "TR55-E6-1",
   "what": "TR-55 Example 6-1: 75 ac (0.117 mi²), Type II, peak 360 cfs held to 180 cfs, runoff 3.4 in",
   "reference": "NRCS TR-55 Example 6-1, figure 6-2 (Worksheet 6a)",
   "compared": 4,
   "maxDiff": "1.25 %",
   "pass": true
  },
  {
   "id": "TR55-E6-2",
   "what": "TR-55 Example 6-2, first stage: 2-year peak 91 cfs held to 50 cfs, runoff 1.5 in",
   "reference": "NRCS TR-55 Example 6-2, figure 6-3 (Worksheet 6a, first stage)",
   "compared": 4,
   "maxDiff": "0.76 %",
   "pass": true
  },
  {
   "id": "HEC22-E10.2",
   "what": "HEC-22 Example 10.2: 43.4 ac, Type II, peak 31.1 cfs held to 19.4 cfs, runoff 0.43 in (printed Rs is rounded before multiplying)",
   "reference": "FHWA HEC-22 4th ed. Example 10.2, steps 3 to 5",
   "compared": 3,
   "maxDiff": "1.29 %",
   "pass": true
  },
  {
   "id": "TR55-F6-1-LOW",
   "what": "Figure 6-1 Types II and III, low end: Vs/Vr about 0.555 at qo/qi 0.1 (read from the curve)",
   "reference": "NRCS TR-55 figure 6-1, read at qo/qi = 0.1",
   "compared": 1,
   "maxDiff": "0.07 %",
   "pass": true
  },
  {
   "id": "TR55-F6-1-HIGH",
   "what": "Figure 6-1 Types II and III, high end: Vs/Vr about 0.175 at qo/qi 0.8 (read from the curve)",
   "reference": "NRCS TR-55 figure 6-1, read at qo/qi = 0.8",
   "compared": 1,
   "maxDiff": "0.54 %",
   "pass": true
  },
  {
   "id": "TR55-F6-1-RANGE",
   "what": "qo/qi of 0.85 is past the end of figure 6-1 (refusal)",
   "reference": "NRCS TR-55 figure 6-1 range",
   "compared": 1,
   "maxDiff": "both refuse",
   "pass": true
  },
  {
   "id": "TR55-E4-1",
   "what": "TR-55 Example 4-1: 25-year peak, 250 ac, CN 75, Tc 1.53 hr, Type II (q_u read from exhibit 4-II in the example)",
   "reference": "NRCS TR-55 (1986) (published example)",
   "compared": 5,
   "maxDiff": "1.01 %",
   "pass": true
  },
  {
   "id": "ARITH-RATIONAL",
   "what": "Rational Method: 6 ac at C 0.85 and 4 ac at C 0.35, i = 5.0 in/hr",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 2,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-NRCS",
   "what": "NRCS mode: 40 ac, CN 74 to weighted CN 88.8, Tc 45 to 20 min, two events, target = pre-development peak; peak, volume and storage by hand",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 27,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-SAME",
   "what": "NRCS mode: the same condition before and after gives no increase",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 5,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-TGT-ABOVE",
   "what": "NRCS mode: a target above the post-development peak gives no storage figure",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 2,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-TGT-OUT",
   "what": "NRCS mode: a target that makes qo/qi 0.05 is outside TR-55 figure 6-1, so no storage figure",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 2,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-RATIONAL",
   "what": "Rational mode: Q = C i A for each condition with its own intensity, weighted C; peaks only",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 7,
   "maxDiff": "0.00 %",
   "pass": true
  },
  {
   "id": "ARITH-PP-REPORT",
   "what": "Report numbers: differences by outlet and event, target from a row or the pre-development flow",
   "reference": "Hand calculation of the published equation (published example)",
   "compared": 11,
   "maxDiff": "0.00 %",
   "pass": true
  }
 ]
}