gageblend.h File Reference

Volume-conserving weighted blend of rain-gage time series. More...

#include <QString>
#include <QVector>
#include <QtGlobal>

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Classes
struct	GageBlend::SeriesPoint
	One (time, value) entry of a rainfall series. More...
struct	GageBlend::SourceGage
	A contributing gage: its series plus everything needed to read it. More...
struct	GageBlend::Box
	A constant-intensity interval, [t0, t1), in depth/hour. More...
struct	GageBlend::BlendResult
	Outcome of one blend. More...

Namespaces
namespace	GageBlend

Enumerations
enum class	GageBlend::RainType {   GageBlend::Intensity = 0 ,   GageBlend::Volume = 1 ,   GageBlend::Cumulative = 2 }
	Rain-data format, matching SWMM_GageRainType. More...

Functions
QVector< Box >	GageBlend::toBoxes (const SourceGage &source)
	Expand one source into explicit intensity boxes.
double	GageBlend::boxDepth (const QVector< Box > &boxes)
	Total depth carried by a box list.
double	GageBlend::engineDepth (const QVector< SeriesPoint > &points, qint64 intervalSec, RainType rainType=RainType::Intensity, double scaleFactor=1.0)
	Total depth of an emitted series under the ENGINE's boxcar rule.
BlendResult	GageBlend::blend (const QVector< SourceGage > &sources, const QVector< double > &weights)
	Blend sources under weights into one INTENSITY series.

Variables
constexpr int	GageBlend::kMaxGridCells = 200000
	Ceiling on grid cells, so a pathological gcd cannot melt the model.
constexpr double	GageBlend::kVolumeTolerance = 1e-9
	Relative tolerance for the volume-conservation check.

Detailed Description

Volume-conserving weighted blend of rain-gage time series.

Author

Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com

Date

2026

License\n GPL-3.0-or-later

Produces the single synthetic series that represents a weighted combination of several rain gages — the data half of an interpolated-gage assignment.

The blend must reproduce the ENGINE's reading of a rainfall series, not the intuitive one. Per Gage.cpp::updateAllGages, an entry at t_k is a BOXCAR, not a hold: it applies over [t_k, t_k + I) where I is the GAGE's recording interval, and rainfall is zero in the gaps between boxes and after the last entry. An entry that starts before the previous box ends preempts it.

Consequently the blend cannot simply union timestamps and combine values — that silently changes total depth whenever the sources' intervals differ. Instead each source is expanded to explicit boxes in the intensity domain, and those boxes are integrated exactly onto a common grid of pitch gcd(intervals). Volume is then conserved cell-wise, and therefore globally, for any mix of intervals and alignments.

Output is always INTENSITY: it is the only rain type whose stored value does not depend on the interval field, so a later edit to the interval — or the h:mm truncation the INP writer applies — cannot silently rescale the total.

Leaf module: no Qt-GUI, engine, or GDAL dependency. Times are plain seconds since the epoch so the module stays testable without QDateTime.