Year-to-year changes of NDR

Hello,

I encountered a similar issue as described on this page, but I still haven’t found a clear answer.

Based on my understanding of the manual, specifically the sentence “Time series of nutrient concentration used for model validation should span over a reasonably long period (preferably at least 10 years) to attenuate the effect of inter-annual variability.,” the NDR model requires inputting the average precipitation over a 10-year period, rather than inputting annual values separately. Is my understanding correct?

In my case, I have a 2015 LULC map and would like to estimate the NDR for each year from 2010 to 2020. Is it acceptable to input the annual average precipitation for each individual year in the model, or is this approach not recommended? If not, how was it possible for this publication to simulate the spatial distribution of water conservation from 2000 to 2019?

Thank for your answer.

Hello @Lee_Bay, and welcome to the forum!

The NDR model was made to represent long-term annual average nutrient flows. So we do recommend inputting the average precipitation over a 10-year period, rather than inputting annual values separately.

That said, people do use the model to represent each year separately. Even though it is not what the model was designed for, it’s ok to model one year at a time, but not to model sub-annual (like monthly) values.

~ Stacie

Thank you, @swolny!

Thank you for your response. I would like to confirm if I understood correctly. You mentioned that the NDR model was not originally designed to simulate nutrient flows year by year, but it is acceptable to use it for individual years as long as I am not modeling sub-annual data (like monthly values). Does this mean that if I want to simulate NDR for each year from 2000 to 2019, I should input the actual precipitation data for each individual year (e.g., 2000 for 2000, 2001 for 2001, etc.)? Or should I use a 10-year average precipitation for each year (e.g., 1995-2005 for 2000, 1996-2006 for 2001, etc.)?

Thank you for your help!

Does this mean that if I want to simulate NDR for each year from 2000 to 2019, I should input the actual precipitation data for each individual year (e.g., 2000 for 2000, 2001 for 2001, etc.)?

Yes, you’ll use the annual average precipitation for each individual year.

~ Stacie