I suggest you check the weather reporting agencies on the internet for nearby
countries exposed to same intertropical front movement - Indonesia, Singapore,
Malaysia, India, maybe Darwin; they should all have such data developed - I
would think also Manila. Adjust as many stations as you can get to your site by
ratio of mean seasonal daily rainfall then average them for each duration and
return period.

A possibly useful reference is Hydrometeorology by Wiesner , Chapman and Hall
(1970)

Another is an article in the ASCE Hydraulics Division Journal by Frederick
Charles Bell, January,1969.
His conclusion was that the relationships derived in the USA by Hersfield are
generally applicable, with only small variation, world wide. You need to have
an estimate of the i-hour 2-year OR the 10-year 1-hour for various durations,
and from that you can ratio up to other return periods with the curves developed
by Bell.

In the absence of either of the above two indices, he also gives an approximate
formula for estimating the 1-hour 2-year based on the mean of maximum annual
observation da precipitation and the mean annual number of thunderstorm days.

In the Journal of Hydrometeorology (American Meteorological Society), June 2004:
"Rainfall Amount, Intensity, Diration, and Frequency Relatopships in the Mae
Chaem Watershed in Southeast Asia", by Koh Dairaku, Seita Emori, and Taikan Oki.
An abstract can be viewed on the AMS website, and a pdf file can be downloaded
but there is a cost. This paper only dealt with 2 years of data 1998 and 1999,
so it would not be of direct benefit to you. However, the authors may have
references available now for the record up to now, 8+ years from which 2-year
return period data might be fairly reasonable.

As for your proposal, it would appear that you have not considered return
period.

Ron Kilmartin
Consulting Engineer
Pleasant Hill, CA


-------------- Original message ----------------------
From: "Russ Faust" <rwf7437@...>
> http://www.weather.gov/oh/hdsc/
>
>
> ----- Original Message -----
> From: Rogelio M. Espinosa
> To: hydrologymodel@...
> Sent: Monday, June 11, 2007 7:37 AM
> Subject: [hydrologymodel] daily rainfall data from non-recording gage
>
> dear members;
>
> I am trying to develop an IDF for our locality using probability analysis.
> However, i have this problem on rainfall data. the only data available is
> daily rainfall depths and duration for about 25 years taken from a non
> recording gage. In developing the IDF, one has to obtain the average
> rainfall intensities for time increment windows of 15 min , 20 min , 30
> min, 45 min, 60 min and up to 72 hrs (either on annual series or partial
> series basis ) and treat these with probability analysis using appropriate
> models. My problem is how to get the average rainfall intensities for time
> increment windows enumerated above with data on non-recording gage. What i
> know is that it would be very much easier if you have outputs from a
> pluviometer. In the absence of data from recording gages , Is it safe to
> say that these average intensities can be computed by merely dividing
> rainfall duration ( say t= 5.0 min ) from rainfall depth (say d = 10 mm )
> and consider the quotient ( i = 120 mm / hr ) as part of time increment
> window of 5 min? if so, what about for rainfall duration not within the
> time increment windows?
>
> any suggestion / s will be greatly appreciated . .
>
> Thnk you and more power.
>
> rogelio m. espinosa
> College of engineering & technology
> western mindanao state university
> zamboanga city, philippines
> telefax no: 062-991-9365