double runoff_getTimeStep(DateTime currentDate)
//
// Input: currentDate = current simulation date/time
// Output: time step (sec)
// Purpose: computes a time step to use for runoff calculations.
//
{
int j;
long timeStep;
long maxStep = DryStep;
// --- find shortest time until next evaporation or rainfall value
// (this represents the maximum possible time step)
timeStep = datetime_timeDiff(climate_getNextEvap(currentDate), currentDate);
if ( timeStep < maxStep ) maxStep = timeStep;
for (j = 0; j < Nobjects[GAGE]; j++)
{
timeStep = datetime_timeDiff(gage_getNextRainDate(j, currentDate),
currentDate);
if ( timeStep > 0 && timeStep < maxStep ) maxStep = timeStep;
}
// --- determine whether wet or dry time step applies
if ( IsRaining || HasSnow || HasRunoff ) timeStep = WetStep;
else timeStep = DryStep;
// --- limit time step if necessary
if ( timeStep > maxStep ) timeStep = maxStep;
return (double)timeStep;
}
void saveAccumRainfall(Project* project, DateTime date1, int hour, int minute, long v)
//
// Input: date1 = date of latest rainfall reading (in DateTime format)
// hour = hour of day of latest rain reading
// minute = minute of hour of latest rain reading
// v = accumulated rainfall reading in hundreths of inches
// Output: none
// Purpose: divides accumulated rainfall evenly into individual recording
// periods over the accumulation period and writes each period's
// rainfall to the binary rainfall file.
//
{
DateTime date2;
int n, j;
float x;
// --- return if accumulated start date is missing
if ( project->AccumStartDate == NO_DATE ) return;
// --- find number of recording intervals over accumulation period
date2 = date1 + datetime_encodeTime(hour, minute, 0);
n = (datetime_timeDiff(date2, project->AccumStartDate) / project->Interval) + 1;
// --- update count of rain or missing periods
if ( v == 99999 )
{
project->RainStats.periodsMissing += n;
return;
}
project->RainStats.periodsRain += n;
// --- divide accumulated amount evenly into each period
x = (float)v / (float)n / 100.0f;
// --- save this amount to file for each period
if ( x > 0.0f )
{
date2 = datetime_addSeconds(project->AccumStartDate, -project->TimeOffset);
if ( project->RainStats.startDate == NO_DATE ) project->RainStats.startDate = date2;
for (j = 0; j < n; j++)
{
fwrite(&date2, sizeof(DateTime), 1, project->Frain.file);
fwrite(&x, sizeof(float), 1, project->Frain.file);
date2 = datetime_addSeconds(date2, project->Interval);
project->RainStats.endDate = date2;
}
}
// --- reset start of accumulation period
project->AccumStartDate = NO_DATE;
}
