How can I create evapotranspiration raster data from CGIARCSI from 2010 -2020 for one of the developing countries? I want to know the AWY f the country and I have tried to extract by mask my study area using the data downloaded available raster data at (Global Aridity Index and Potential Evapotranspiration Climate Database v2 – CGIAR-CSI) with ArcGIS Pro, but no specific time range generated. Please help
Hi @ADIGUN -
This CGIAR data represents long-term annual average values (which are appropriate for the AWY model) they do not supply individual years of data. As their website says, it’s based on WorldClim climate data, which is also an annual average over the years 1970-2000.
~ Stacie
Thank you for your response, @swolny .
However, can I input the extracted by mask of the CGIAR evapotranspiration data (ArcGIS Pro) and precipitation map of 2010 - 2020 into InVEST? If not, suggest where to get evapotranspiration raster data besides CGIAR to match my Precipitation data.
Thank you
We recommend making sure that the evapotranspiration data is based on the same precipitation data that is also used as input to the model. Are you using WorldClim precipitation data? If not, then I suggest either looking for different ET0 data that is based on your precipitation data, or calculating ET0 from your precipitation data using one of the methods mentioned in the User Guide.
~ Stacie
Thank you for this beautiful response @swolny
I made my precipitation map from CRU V4.07 data using ArcGIS Pro. Kindly help me with the procedure to prepare a precipitation and evapotranspiration map from WorldClim precipitation data because they are monthly data. In addition, kindly suggest where I can download a good resolution (10m to 30m) of LULC map for developing countries in a continent like Africa.
Best Regards
Hi @ADIGUN -
To create an annual average precipitation map from the WorldClim data, you just need to add the monthly rasters together.
No matter where I’m working in the world, I look for land cover data created in the country itself, for example from a government geospatial website. Many countries have their own land cover map, and it is often the one most trusted by local partners.
The User Guide notes a couple of global land cover resources, but they are at much coarser resolution. A web search will lead you to a couple of global products at 10m resolution, like ESA’s WorldCover, which you can consider. It is important to evaluate whether a given land cover map represents your study area well. I’ve found that the same global source may be satisfactorily accurate in some places, and not very accurate in others.
~ Stacie
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Thank you once again @swolny
I am indeed grateful for your response. I have so many questions because I am new to the InVEST model. How do I prepare the evapotranspiration map from WorldClim data? I was given only downloaded monthly Tmin and Tmax.
Thank you
Thank you once again @swolny
I am indeed grateful for your response. I have so many questions because I am new to the InVEST model. How do I prepare the evapotranspiration map from WorldClim data? I was given only downloaded monthly Tmin and Tmax.
Thank you
If you decide to use WorldClim for precipitation data, then you can use the CGIAR evapotranspiration data, because it is based on WorldClim. That way you don’t need to calculate ET, it’s already done for you.
~ Staice
I am indeed grateful for this @swolny
The last question is, can we use CGIAR evapotranspiration for WorldClim precipitation data from 2001 to 2010? If not, how do I calculate the ET for that year on ArcGIS Pro using Tmax and Tmin of WorldClim data?
I appreciate your support and guidance. Thank you
I am indeed grateful for this @swolny
The last question is, can we use CGIAR evapotranspiration for WorldClim precipitation data from 2001 to 2010? If not, how do I calculate the ET for that year on ArcGIS Pro using Tmax and Tmin of WorldClim data?
I appreciate your support and guidance. Thank you
As the WorldClim web site says, their “historical” data covers years 1970-2000. And as the CGIAR web site says, since it is based on WorldClim, their ET data also covers years 1970-2000. Neither WorldClim nor CGIAR provide climate data from 2001-2010 (but I wish they would!), so if you specifically want those years then you’ll need to use different precipitation data.
The InVEST User Guide provides a couple of options for calculating ET from precipitation, temperature, solar radiation and/or other relatively easy-to-obtain data. I generally use modified Hargreaves, and CGIAR uses Penman-Montieth, both of which you can find lots of information about. CGIAR links to papers with their methods, which might be useful.
~ Stacie
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Thank you @swolny
Please I have been having difficulties preparing my Isohyetal map from observed data because I only have one gauge station for my study area of about 4500 square kilometres. How can I prepare my 2000, 2005, 2010, and 2015 Evapotranspiration and Precipitation map from WorldClim monthly weather data?
Thank you
If you use WorldClim (as described previously), you will have a precipitation map that represents an annual average over the years 1970-2000. You may use this precipitation map (and the CGIAR ET map derived from it) for model runs where your land cover maps are from 2000/2005/2010/2015, but you should note to your audience the difference in time coverage, and describe why WorldClim was the “best available” data, even though it does not include your years of interest.
It would indeed be better to use data that include the years 2000-2015 if you can, but then you might need to do more work to create those datasets. I am not familiar with most of the other precipitation datasets out there, so cannot make a strong recommendation, but there are several to choose from, some of which do include more recent data. Our User Guide mentions CRU, and I think CRU TS includes a “pet” evapotranspiration layer (so you would have both precipitation and ET from the same source), but its resolution is rather coarse. For other options, you’ll need to do a web search and see what fits your needs. One example is this comparison table of precipitation data from NCAR (Precipitation Data Sets: Overview & Comparison table | Climate Data Guide).
If the dataset you finally choose does not include evapotranspiration, the User Guide provides guidance for calculating the “modified Hargreaves” equation, and you can follow that to calculate ET.
~ Stacie
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