hi
1-i wanna know in drought condition how can i change dam operation rules based on the fraction of downstream demands?
2-to define the resiliency and vulnerability, do i have to work on results or can i define those parameters inside weap?

Hi Soroosh,

1) In the expression builder, I would use an "if statement". Here's an example of one.

If(Or(Year<2000, And(Year=2000, TS < Apr)),5,
Key\Drought, MonthlyValues(Oct, 15, Nov, 25, Dec, 25, Jan, 25, Feb, 16, Mar, 26, Apr, 46, May, 33, Jun, 33, Jul, 33, Aug, 26, Sep, 15),
MonthlyValues(Oct, 20, Nov, 25, Dec, 25, Jan, 25, Feb, 16, Mar, 26, Apr, 46, May, 43, Jun, 43, Jul, 43, Aug, 34, Sep, 20))

This says that if the year is before April 2000, have an instream flow requirement of 5. Otherwise, ask if there is a drought (that's another if statement). If there is a drought, use the monthly streamflow requirements given. If there is not a drought, us the other monthly streamflow requirements. You can make a similar sort of if statement in the Expression Builder for the reservoir operation.

2) I would recommend reading the section "User-Defined Variables" in the WEAP help menu to get a sense of what you can do.

thanks very dear stephanie
in expression builder in user-defined variables section,since you are an expert and very kind and nice would you please tell me, can i sum up all (time steps) forexample unmet demands for one variable and use it in a formulation?

Hi
if your hedging rules are only base on the current condition of the resrvoir volume or elevation you can simply define that at the expretion builder in the operation menue, buffer section
if your rules are base on the some other variable like demands(catchments) witch calculate during each time step you should you scripting method. ==> advanced==>event script==>before supply.

hi dearest ali
I wanna thank again you and steph, I almost got where I wanted with your guidance, thank you.
but please add any comment that you think may help me here in this context.

ok another question
in hedging a demand, when there are two branches upstream with reservoirs on each, how do we formulate the start of hedging? (the hedging is based on storage of reservoir )

Hi Soroosh,

WEAP allows for different sections of the dam volume, and a buffer coefficient when the dam goes below a certain level that you specify. This will allow you to be conservative or liberal with your dam hedging. You can read more about it in the WEAP help menu: search for "Reservoir Zones and Operations."