Hydrologic Trend Analysis Tool

Hydrologic Trend Analysis Tool (HTAT) is a Python script tool for use with ArcGIS 10 that allows the user to define a land region on the included ArcGIS map and obtain monthly time series charts and tables for various water budget components associated with the region. Specifically, the Gravity Recovery and Climate Experiment (GRACE) satellite mission provides data on total Terrestrial Water Storage (TWS) anomaly for the region, and the Global Land Data Assimilation System (GLDAS) models provide data on soil moisture (SM) and snow water equivalent (SWE) anomalies for the same region.

The tool references an included static data package that currently extends from February 2003 through December, 2013. Therefore, the user should check this site periodically for updates to the data package and tool. Included in the package are monthly ArcGIS rasters of GRACE TWS anomaly, Mann-Kendall TWS trend rasters, as well as various supporting files, such as Hydrologic Unit Code (HUC) and political boundaries. Users should read the "Tool_Instructions" pdf for detailed instructions on how to install and use the tool. Specifically, in order to run the tool, the user will need to install the Scipy Python module (included), if it is not already installed in their ArcGIS Python distribution. However, the user can access the monthly GRACE rasters by simply opening the "MAP_HTAT" map file and then opening the Time Slider window within ArcGIS.

Feedback can be directed to Arthur Ryzak (

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