Infiltration Horton fit calculator

Calculate fitted initial rate f0 and fitted asymptotic rate fc with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use fitted initial rate f0 and fitted asymptotic rate fc to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Elapsed infiltration observation times (hours)
0,1,2,3
Measured infiltration rates (mm/hour)
50,24.7151776469,15.4134113295,11.9914827347
Minimum decay k bound (per hour)
0.01
Maximum decay k bound (per hour)
5
Fitted initial rate f0 (mm/hour)
50
Fitted asymptotic rate fc (mm/hour)
10
Fitted decay k (per hour)
1
Fit RMSE (mm/hour)
0

Try another scenario

Elapsed infiltration observation times (hours)
[1, 1, 2, 3]
Measured infiltration rates (mm/hour)
[50, 24.7151776469, 15.4134113295, 11.9914827347]
Minimum decay k bound (per hour)
0.01
Maximum decay k bound (per hour)
5
Fitted initial rate f0 (mm/hour)
178.081427
Fitted asymptotic rate fc (mm/hour)
11.359292
Fitted decay k (per hour)
1.858298
Fit RMSE (mm/hour)
8.939535
Calculation method

Calculation method

Fitted initial rate f0 (mm/hour)

Horton f(t)=fc+(f0−fc)e^(−kt), profile linear least squares in f0,fc at each k; bracket negative-to-positive profile-derivative zeros on64 bounded subintervals, refine roots, compare stationary candidates and bounds. Reject nonphysical fitted rates.

Fitted asymptotic rate fc (mm/hour)

Horton f(t)=fc+(f0−fc)e^(−kt), profile linear least squares in f0,fc at each k; bracket negative-to-positive profile-derivative zeros on64 bounded subintervals, refine roots, compare stationary candidates and bounds. Reject nonphysical fitted rates.

Fitted decay k (per hour)

Horton f(t)=fc+(f0−fc)e^(−kt), profile linear least squares in f0,fc at each k; bracket negative-to-positive profile-derivative zeros on64 bounded subintervals, refine roots, compare stationary candidates and bounds. Reject nonphysical fitted rates.

Fit RMSE (mm/hour)

Horton f(t)=fc+(f0−fc)e^(−kt), profile linear least squares in f0,fc at each k; bracket negative-to-positive profile-derivative zeros on64 bounded subintervals, refine roots, compare stationary candidates and bounds. Reject nonphysical fitted rates.

Symbols and units
a
Elapsed infiltration observation times (hours)
b
Measured infiltration rates (mm/hour)
c
Minimum decay k bound (per hour)
d
Maximum decay k bound (per hour)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • User-supplied measurements and assumptions; Bounded variable-projection least squares for Horton f(t)=fc+(f0−fc)e^(−kt); reject nonphysical fitted rates. Supported limits: Finite numeric values bounded to 1e9 magnitude; lists and tables contain 1–100 records unless a stricter bound is stated. Inputs use the units shown. Lists explicitly paired by a method must have matching lengths; independent polynomial coefficient vectors may differ. Respect stated physical, interpolation, policy and computational domain limits. At least three distinct observation times are required for a three-parameter fit; the scalar decay bound is finite and positive.
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Further reading

Method reference ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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