Subject: How to forecast headflow data through water year method Posted: 2/19/2017 Viewed: 287 times
I have the headflow data from 2006 to 2011. But if I want to use the water year method for future let say for the year 2020, so how to work out. Actually, how to know that weather in future there will be a dry or very dry condition and also need to know how to set the definitions for dry and very dry and also how to enter the sequence of a condition in future.
Subject: Re: How to forecast headflow data through water year method Posted: 2/20/2017 Viewed: 223 times
It sounds like you have already reviewed the Water Year Method, and conducted the activity in the tutorial (if you haven't, that's a great place to start).
Basically, you are asking how to know the future. Unfortunately we still don't have a good answer for that. I don't know how dry it will be, and I don't know the sequence of dry years and very dry years. But your job as a modeler is to test the *possibilities* for your basin, and that should include looking at extremes as well as non-extremes.
Therefore, I suggest you run several different scenarios where you experiment with the definitions of dry and very dry and experiment with the sequences in the Water Year methods. This won't tell you exactly what will happen in the future, but it will give you a range of possible futures, and the impacts on local water supply. Maybe everything will be fine. Maybe you will discover a threshold under which the water supply is unacceptable. The point is to understand the possibilities, not to know the future.
You can also look at the recent IPCC report and think about the trends in the various predicted RCPs. But those will tell a similar story - "we don't know the future, but here are some of our guesses of what it could be."
Hope this helps.
Subject: Re: How to forecast headflow data through water year method Posted: 2/21/2017 Viewed: 216 times
Thank you for the reply.
I also have one doubt if I use catchment to enter the irrigation demand then how can I enter the reference evapotranspiration data if I don't have the climate data like radiation, temperature etc required for the penman-monteith method.
Subject: Re: How to forecast headflow data through water year method Posted: 2/21/2017 Viewed: 186 times
It is often the case with models that we don't have all the data we want. In this case, you may have to make assumptions based on similar systems. Be sure to write out these assumptions very clearly in your reports about the results.
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