Hi members, i would like to adapt a reservoir (working as infiltration basin with a surface to groundwater transfer link) to also function as flood control i.e. to empty in time for an incoming storm in 'real time'. Has anyone done this before in WEAP? I could do RTC in MATLAB (Simulink), how would i couple this with WEAP.

Hi John,

I'll give you a two part answer:

For emptying before an upcoming storm, you would need to make an expression that examined precipitation data for upcoming timesteps (this would work best for a daily or weekly model).

More generally, what you can do, and what I suspect is a good approximation for real life management, is program the reservoir to empty before the rainy season. To do this, go to the reservoir data, then to Operation, and under Top of Conservation, open up the Monthly Time Series Wizard. You can change the fill level to be lower just before the rainy season so that the reservoir empties(you can also change the top of the buffer too).

Thanks Stephanie. The 1st option would work well. How would you implement that in WEAP?

Hi John,

For the first option, you'd have to have a daily or weekly model, which comes with its own implications, so be cautious of that.

Then you'd have to require higher releases from the dam at times before storms. A couple things to consider here:
1) Are the release quantities determined by the size of the storm? (that will require more detailed expressions)
2) Are storm forecasts reliable in this region? (if not, you are assuming perfect knowledge in a system where that doesn't exist, and that will create a difference between the model and reality).
3) How soon before a storm (days?) would a release decision go into place?

Next you would have to implement the release with an "if" statement within the top of conservation of your reservoir. You'll have to fill in all the variables themselves, but it would look something like:

If( [it is going to be very rainy], [lower value for top of conservation],[normal value for top of conservation] )

There is a way to use the PrevTSValue function to look ahead. Normally, you tell PrevTSValue how many timesteps previous to look, but if you specify a NEGATIVE number of timesteps, you will look ahead into the future. This only works with future values of DATA variables -- you cannot get future values of RESULT variables.

For example, in the Tutorial on Hydrology, here is an expression to look at the precipitation for the upcoming month:

PrevTSValue(Demand Sites and Catchments\Agriculture Catchment:Precipitation[mm], -1)

If you wanted to sum up the values for the next seven timesteps (e.g., the next week in a daily model), it would be

PrevTSValue(Demand Sites and Catchments\Agriculture Catchment:Precipitation[mm], -1, -7, Sum)


Jack

Thank you Jack and Stephanie for the great suggestions. I will try them and share what happens.