Global dataset for evaluating impact of topographic factors on hydrologic response to climate variability

The dataset contained here was used to document the biomes in the world that show high sensitivity in their hydrologic response to interannual changes in climatic forcing during the 2001-2016 period, while evaluating the role of major topoclimatic factors in modulating these responses. To do this we generated a hydrologic sensitivity index (HSi). HSi evaluates the absolute ratio between the changes of the climatic conditions (dryness index, DI) and hydrologic response (evaporative index, EI_R) between consecutive years (e.g. HSi= |∆ EI_R /∆ DI|). HSi was computed for every successive pair of years from 2001 to 2016.  A total of 15 HSi maps were obtained representing the HSi for each consecutive pair of years.  For each map, where HSi >1, regions are classified as Sensitive and for HSi ≤1, Resilient. To provide a synthesis of the general trend of global hydrologic sensitivity, we display the frequency of HSi, showing the recurrence of HSi >1 for every non-ocean location with a range of 0 (low frequency) to 15 (high frequency). Regions where frequency HSi≥7 are considered highly recurring and as such are deemed as the most hydrologically sensitive. 

This dataset includes the code and raster data to evaluate the effect of the topography on HSi to plot the average frequency HSi for all elevations, aspects, and slope steepness against  latitudinal change. We used global digital elevation models (DEMS) from the Shuttle Radar Topography Mission (SRTM) data (90 m resolution; version 4, for latitudes < 60◦ N and GTOPO30 (1◦ resolution; http://lta.cr.usgs.gov/GTOPO30) for latitudes > 60◦ N. Slope and aspect maps were derived from the DEMs using standard GIS-based methods in ArcMap 10.7.Elevation range used is [0,7000] meters above sea level (m.a.s.l), aspect (N, NE, E, SE, S, SW, W, NW) specifically above slope values greater than 10-degrees (no flat areas used), and slope [0,90] degrees.

Contents:

• 1 MATLAB with the code ready to use
• 1 PDF file with the same code
• 27 geotiff files for elevation (dem#1-27.tif)
• 27 geotiff files for frequency HSi (freq#1-27.tif) 

Note: the following files of slope and aspect could not upload in repository due to exceedance in storage limit: 50MG. The DEM files must be run in ArcMap using slope and aspect tool to produce the following files with the following names.

• 27 geotiff files for slope (slope#1-27.tif)
• 27 geotiff files for aspect (aspect#1-27.tif)