Data

DATA

At WaterITech our mission is to contribute to a sustainable use and management of the world’s precious water resources.


We are leading experts in hydrological and ecological modelling, and apply models to help analyze how different management choices may impact a water system.

Our models can be plugged into the unique solutions by WaterWebTools.com, which enables operational hydrological and ecological forecasting for any location in the world.


This makes our solutions highly relevant for water managers worldwide.

SWAT+ DATA

To help facilitate you, our partners, and other interested parties in applying one of the world’s most comprehensive hydrological models, namely SWAT+, we have prepared a guide for how to access key global data sources, which enable model applications for any location in the world.


We offer this guide and datasets with the hope that more people, including students and professionals, will be able to apply complex models such as SWAT+, which could ultimately support a more widespread use of state-of-the-art science in decision-making processes.

SWAT+ requires four key data sources for its applications (see below).


Digital elevation map

Soil map

In this page, you can learn how to acquire all these data from free globally available sources, which will allow you to set up a model from scratch, for any location in the world.


We have also produced a series of video tutorials, which demonstrate how you may process these global datasets by a series of GIS operations (e.g. clipping data for your area of interest), so that they can be applied in the SWAT+ model.


Please visit our Training page to find these videos.

Land cover map

Weather data

DIGITAL ELEVATION MAP

There are several datasets with global elevation data. For watershed delineations, we have had good experiences with The Shuttle Radar Topography Mission (SRTM) data. This was initially produced through a partnership between NASA and the National Geospatial-Intelligence Agency (NGA), where the NASA Space Shuttle Endeavour orbited the Earth 16 times in 2000, collecting radar data over approx. 80% of the Earth's land surface. The SRTM data has since been refined to flatten water bodies, better define coastlines, remove spikes and wells, and fill voids, and the most recent version (v3) from 2014 provide worldwide coverage of void filled data at a resolution of 1 arc-second (30 meters). https://doi.org/10.5066/F7PR7TFT

 

To access and download the SRTM data, we recommend using the Earth Explorer system (https://earthexplorer.usgs.gov/) by USGS. This requires you to create a free EarthData account, which will enable you to download the dataset (choose the SRTMGL1 data, which is 30 meter resolution) for any location in the world.

Learn how to download and process SRTM data for your next SWAT + setup by watching our training video.

SOIL MAP

Local soil properties can greatly influence the hydrology of a watershed. Complex hydrological models such as SWAT+ therefore also requires a large set of soil parameters to be able to simulate accurately the hydrology of a watershed. Parameterizing different soil types is often a cumbersome and difficult process that often requires application of a range of pedo-transfer functions, which can translate soil textural properties into the soil parameters needed by the model. While the SWAT+ model comes with a global soil dataset, more detailed datasets are available, which could improve the performance of the model. One of the most detailed global datasets available is the Harmonized World Soil Database (HWSD) compiled by FAO and IIASA. The most recent version (v1.21) is from 2012, which comes in a horizontal resolution of 30 arc-seconds (1 km), and two soil layers: topsoil (0-30 cm) and subsoil (30-100 cm).

 

WaterITech has produced a SWAT+ compatible soil database for HWSD, and a soil lookup table, which together with the soil map are needed for the model application. We utilized the review of pedo-transfer functions by Abbaspour et al. 2019 (doi.org/10.1038/s41597-019-0282-4), and derived all the required soil parameters in SWAT+ format using the median output value for a range of different pedo-transfer functions available for a given soil parameter. This unique dataset will provide you with a good basis for your model application, no matter where you are in the world. You can download the files right here:

a zipped raster file, 21 MB

in SWAT+ format, 8 MB

in SWAT+ format, 0.2 MB

LAND COVER MAP

Land cover impacts the hydrology of a watershed, as it influences the permeability of the landscape, and also the level of evapotranspiration, which varies for different types of vegetation and management. Land cover is also highly important for simulating sediment and nutrient processes within a watershed. There a several good global land cover maps available. The European Space Agency started producing the global GlobCover maps based on the Envisat satellite in 2005. The most recent map is from 2015, and comes in a resolution of 300 m. To be able to utilize this map in a SWAT+ application, you need a lookup table that translates the GlobCover land cover types into the corresponding SWAT+ land cover types available in the SWAT+ general database. WaterITech has prepared a lookup table specifically for this purpose. You can download the files right here:

a zipped raster file, 345 MB

in SWAT+ format, 0.2 MB

WEATHER DATA

Accurate weather data, and in particular precipitation data, is a key to be able to simulate the temporal and spatial dynamics of hydrology in a watershed. Ideally, local weather data is available, which can easily be formatted into SWAT+ format, and used as input to your model application (the required format is described in the SWAT+ manual available here: https://swatplus.gitbook.io/docs/user/io).

 

If you do not have good weather data for your area, you can instead use reanalysis data, some of which is now provided at a detailed spatial and temporal resolution. One of the best globally available reanalysis datasets is the ERA5 data produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). ERA5 comprise hourly data of all the weather parameters required by SWAT+, and covers the entire Earth on a 30km grid for the period 1950 to present. ERA5 data can be downloaded using the Climate Data Store Application Program Interface (CDS API). Downloading and formatting the ERA5 data into SWAT+ format requires some programming skills (https://cds.climate.copernicus.eu/api-how-to).

 

Alternatively, you can download the somewhat coarser Climate Forecast System Reanalysis (CFSR) data from 1979-2014, through the SWAT website (https://globalweather.tamu.edu/). The raw CFSR comprise 6 hourly data at a resolution of approx. 38 km for the entire Earth. The advantage of this dataset, when downloading this through the SWAT website, is that it has already been formatted into SWAT format.

SUPPORT BY WaterITech


If you would like assistance with data formatting or a model application, please feel free to contact us at WaterITech.