How to convert discharge m3/s to mm of discharge ?

divide discharge (m3/s) by area of your basin then you get  it in m/s.If you have your precipitatin in mm/month, you could then get mm/month for discharge by

Q (mm/month) = Q(m^3/s) *1000*24*number of days in month*3600/ Area (m^2)

First calculate specific runoff: q = (Q*1000)/A

Q - discharge, A-catchment area

Second runoff (R -mm) R=q*31,56

31,56 number of second in year minus 6

Similar to what Mohammad said with an extra explanation:

divide discharge (m3/s) by area of your basin then you get  it in m/s.If you have your precipitation in mm/day, you could then get mm/day for discharge by

Q (mm/day) = Q(m^3/s) *1000*24*3600/ Area (m^2)

Of course, that depends on how often your data is taken, if you have one measurement monthly then you'd be assuming that it was a monthly average multiplying the Q(mm/day) by the number of days in the respective month and similar to year.

If you actually had measurements taken throughout all day in m^3/s lets say every hour then you first convert your Q(m^3/s) to Q(mm/hour):

Q (mm/hour) = Q(m^3/s) *1000*3600/ Area (m^2)

and then add all the 24 measurements in mm/hour you have on each day, that will give you Q(mm/day). 

Thank you so much for the clear description Andres Peralta Tapia, Mohammad Javad Tourian and Ivan Radevski. 

If your problem is related to single event simulation, above answer is correct after subtraction of baseflow. 

You must calculate the quantity of water discharged to the area at the time , then divided water quantity (m3) by the area(m2) which received the water. you will get the water depth in m. Multiplying the water depth(m) by 1000 to get water quantity as mm depth.  

Hello,

it's easy, so, you follow this step, 

divide discharge (m3/s) by area of your basin then you get  it in m/s.If you have your precipitatin in mm/month, you could then get mm/month for discharge by

Q (mm/month) = Q(m^3/s) *1000*24*number of days in month (31, 30, 29 or 28)*3600/ Area (m^2)

How to convert discharge m3/s to mm of discharge ?. Available from: https://www.researchgate.net/post/How_to_convert_discharge_m3_s_to_mm_of_discharge [accessed Mar 29, 2015].

Hi Kabi Raj,

It will depend on the time-scale you want (hours, day, or month). It will also depend on how often the measurements are taken which will eventuallly affect your data and your analysis as well. First, you need to convert the discharge (volume per second) in to volume per month, if you go for monthly analysis, for example.

Multiply the rate (m/s) by the number of seconds in a day (86400) to get the total for a day. Then multiply this by the number of days (e.g 28, 30, 31). You will get m3/ month. Then divide this by the area of your catchment. This will give you units in meters (remember to convert to m2 if your area is in km2), which is actually the depth. You can convert the meters to cm or mm.

Dear friends:

Away from the aritmethics, One very importan question is to know which is the area of the catchment , that your know or not know, that is contributing to the total volume of flow, thay your are using.

Best regards, Marcelo Jorge

Hi Kabi,

Several answers already. But, whatever is the objective of your researh, please have a look at the attached paper. See the contents under the heading: Virgin flow calculation and validation. Any question, please do not hesitate to ask...

The previous answers gave the solution; you just need to consider the dimensions (m3/s or mm) and to find how you can shift from one to the other.

This is a very basic calculation in hydrology. The important matter herein is that for being able to compare both rainfall and discharge, both of them have to be INTEGRATED in the same period of time... so if you have monthly rainfall expressed in mm (indeed, mm month-1) you cannot compare it to discharge integrated daily (i.e. mm day-1), despite the fact that both of them are expressed in mm. You have to understand that either of those two hydrometeorological variables represent VOLUME of water, expressed in mm, over a common (catchment) area (collected in a given period). Further, once either rainfall or discharge are expressed correctly in mm (time-1), then the catchment area looses its meaning (i.e. it is valid for any catchment area).... Hope it helps. Regards.

Hello,

divide discharge (m3/s) by area of your basin then you get  it in m/s.If you have your precipitatin in mm/month, you could then get mm/month for discharge by

How to convert discharge m3/s to mm of discharge ? - ResearchGate. Available from: https://www.researchgate.net/post/How_to_convert_discharge_m3_s_to_mm_of_discharge.

1mm= {(discharge in m3/sec)*1000*86400* No. of days obtained discharge}/cca (in m2)

Sometimes this process deceives us as it looks simple, but can easy to get lose or confuse along the way, I have faced this kind of furious in conversion a lot of time, especially in the examination. I have seen previous explanation and also agree with their great sharing,

I just also found a link with a simple explanation with picture visualization that can be easier to tell than just a formula:

http://www.fao.org/3/r4082e/r4082e05.htm#4.1.1%20amount%20of%20rainfall

m3/sec * 86400 = m3/day

(m3/day)/catchment area (m2) = m/day

(m/day)*1000 = mm/day

mm/day * 30.41 (or no. of day in a specific month) = mm/month

mm/month * 12 (or mm/day * 365) = mm/year

http://www.tvrl.lth.se/fileadmin/tvrl/files/vvr111/9._Runoff_Calculations.pdf

Q(mm/day) = Q(m3/s) * 1000 * 24 * 3600/area of basin (m2)

be careful you have obtained the correct area of your basin

Hi Dr Kabi Raj Khatiwada . If you fix the area the m3 becomes m (length is variable only). If you fix time then the time can not be considered variable(not appear in the scale x or y) . So from m3/s, only m remains variable . This variable in m can be written in smaller unit which is mm.

The catchment area is multiplied by the depth of rain that falls on it to give the total volume of water produced. For more information. Try this tool

Thanks all...this is the best hint! "Q(mm/day) = Q(m3/s) * 1000 * 24 * 3600/area of basin (m2)"

Please, how to convert meter cube of water in mm?

For example, water use efficiency (WUE) (Kg/ha/m3) in WUE (kg/ha/mm)

Byamungu Zabuloni

WUE in 1 kg/ha/m3 is equivalent to 0.01 kg/ha/mm

Thanks a lot! I have been struggling to get this