Immedaite Help Is required

1. Feb 11, 2010

remaan

Hello every one, I wish if you could help with this problem :

b]1. The problem statement, all variables and given/known data[/b]

Given the following informaiton for a paritculart watershed, determine the amount of the annual precipitaion recieved

2. Relevant equations

water shed area : 4530 m^2
average flowrate : 39.6 m^3/second
Average infiltration 9.2 * 10 ^ -7 m/s
Evapo-transpirtaiton : 45 cm/year
change is storage -23.9 cm/year

3. The attempt at a solution

I am sure that the formula to solve this is : change in storage = input - output + prec. - Evaportaion .

However, I have some doubts :

First, I assumed that the Evapo-transpirtaiton is the same as : Evaportaion so I am going to substitute it in the formula .

Second, which is the major :
The units - do we need to convert the units ?
My idea is to convert all cm to m but then when prec.is found : how to know if m/year

or m/s ?

2. Feb 12, 2010

Lok

Just transform all to a single unit. No matter what transformation you make if you have a single set of units the result will be right. And after you can transform the result in any unit system you want or anything that fits better, m/year maybe.

e.g.

m instead of any other lenght unit
year instead of second .......as at such a surface area the second seems small.

3. Feb 12, 2010

remaan

oh,
so, you're saying that I need to make all cm to m and all seconds to years.

But the numbers will be sooo big because there are a really huge amount of seconds in one year ..

So, is that ok ?

4. Feb 12, 2010

Staff: Mentor

That's where the scientific notation (6.02x1023) comes in handy.

Last edited by a moderator: Aug 13, 2013
5. Feb 14, 2010

remaan

Ok, thnx I 'll try this >

6. Feb 14, 2010

Senjai

Borek you made me laugh :)

7. Feb 14, 2010

remaan

But, what if I got powers with(-) sign ?

8. Feb 15, 2010

Staff: Mentor

That's OK, that's part of the notation. Do you know what it means?

Last edited by a moderator: Aug 13, 2013
9. Feb 18, 2010

remaan

ya .. thnx alot