Subject: Dear WEAP Users, Posted: 4/8/2015 Viewed: 22827 times
1. I have a river discharge/flow/runoff of main river, If I add this flow as a head flow to WEAP, can WEAP calculates the available water automatically in the basin that I am doing in my research or Will I need to use an other hydrological model to calculate the river flow?
2. Is it possible to use river flow 25 years ago from 1960-1990 as a current year and forecasting year 2016-2060? Or is t neccesary to have recently discharge?
Thanks for your time and consideration.
Ms. Stephanie Galaitsi
Subject: Re: Dear WEAP Users, Posted: 4/8/2015 Viewed: 22794 times
Dear Mr. Hussein,
You can specify the river headflow. In the data tree, go to Supply and Resources/River/[Name of your river] and then click the tab Inflows and Outflow and fill out the Headflow (remember to start with Current Accounts). I recommend using the Read From File Wizard if you are modeling 1960-1990. Note that the value of this flow will not change until other elements in WEAP add more supply or remove supply, so make sure this value represents the value of the river in the area you are modeling, and not upstream.
To answer your second question, there's nothing in WEAP to stop you from using data for different years, but I would recommend using it for the correct years so that when it is time to calibrate, you can test your model against data from those years as well without confusing demands or infrastructure developments from different years. Also, if you are using old data to model current data, ask yourself if the system has changed, such as land use upstream, that might make this old data no longer representative.
If I were you, I would use the Water Year Method. It is explained in the Tutorial - it's the last part of the "Scenarios" module.
Thank you very much for your prompt response. Well understood your response, again could you please clarify me the second question for example how the old data from 1960-1990 which is a 25 years ago represent my current study while obivous there is land use change in upstream while downstream ( my study area) no development current but from 1960-1990 existed development projects (Note: the Basin is transbundary river basin and my study area is downstream of the basin).
The other question is: incase if I use the old data of the river flow, is it must also to use the other WEAP input data with the same year or I can use the current data e.g population, and other WEAP required data?
Thanks again for your time.
Ms. Stephanie Galaitsi
Subject: Re: Dear WEAP Users, Posted: 4/9/2015 Viewed: 22771 times
Glad to help.
For using old data - the river flow may be substantially different than what it was in 1960-1990. This may be due to irrigators withdrawing more water during the summer, or it might be due to more runoff from urban areas during the winter. Or a thousand other things. So if you use old data to predict current flow, you may find it is not representative of the hydrological system, or the water the system can provide. It also will be hard to calibrate your model because the current data (for water diversions and instream flow, for example) did not come from that streamflow.
There is nothing stopping you in WEAP from mixing and matching data from different years, but again it is an issue of calibration. How will you know that your model is operating correctly if you can't compare it to real data? It is easy to input data into a model - the challenging part is showing that the model can then approximate the actual system.
Thanks for your technical support. I run the model with the recently available data, 2002-2014 river flow so I have two questions:
1. I used as current account 2002 and from 2003-2055 so How can I pridict future flow from 2015-2055 by using WEAP? and how will be demand for all water users if I have updated data of 2014 for example 2014 irrigated area, 2014 population census and so on but my current account is 2002. Or else I will use the same data from 2002-2014 then from 2015 for future projection data
2. Regarding to the calibration, I tried to use PEST as automatic but error, so what are the exact parameters to use calibration?
Ms. Stephanie Galaitsi
Subject: Re: Dear WEAP Users, Posted: 5/20/2015 Viewed: 22556 times
These are great questions.
If you're using streamflow to drive your model (as opposed to catchments), you can use the Water Year Method to model the future. The Water Year Method (which is explained in the "Scenarios" section of the WEAP tutorial). The Water Year Method allows you to use a year of data that you already have (this captures the seasonal pattern of the river) and then for the years afterwards, you can say whether it's a dry or wet (or very dry/very wet) variation on that pattern.
I recommend creating a reference scenario and then creating various water year method scenarios, perhaps 1 looking at a succession of dry years, 1 looking at alternating dry and wet, etc. This gives you a sense of how your system will respond to different environment circumstances (because of course we don't know the future, but we want to be prepared for even the worst possibilities.
For the PEST Calibration, have you read through the PEST section in the WEAP Help Menu? At the top of WEAP, open the menu, open the "Help" menu, and open "Index" and then in the window, click search and type "Pest" and then click enter. That will bring up a lot of information - it has a section about parameters.