HII POPULATION DENSITY DRIVER

What does this task do?

This task calculates the impact of population density on the terrestrial surface as one of the key drivers for a combined Human Impact Index⁠. "Impact" is a logarithmically scaled pressure score based on population density. The output HII driver calculated by this task is, like all other HII drivers, unitless; it refers to an absolute 0-10 scale but is not normalized to it, so the actual range of values may be smaller than 0-10.

The source population density cells are derived from the WoldPop Population Data dataset developed by WorldPop⁠. This dataset models the distribution of the global human population annually beginning in 2000 at a spatial resolution of 100 m. As a class property of HIITask the original dataset values are converted from the number of people per 100m x 100m grid cell to actual population density of people/sq km.

The pressure score is calculated as

pressure score = 3.333 * log(population density + 1)

Population density values above 1000 are given a maximum pressure score of 10. This directly follows the logic by Venter et al. 2016⁠.

Values are multiplied by 100 and converted to integer for efficient exporting to and storage in the Earth Engine HII Population Density Driver image collection (projects/HII/v1/driver/population_density).

Variables and Defaults

Environment variables

SERVICE_ACCOUNT_KEY=<GOOGLE SERVICE ACCOUNT KEY>

Class constants

scale=300

Usage

All parameters may be specified in the environment as well as the command line.

/app # python task.py --help
usage: task.py [-h] [-d TASKDATE] [--overwrite]

optional arguments:
  -h, --help            show this help message and exit
  -d TASKDATE, --taskdate TASKDATE
  --overwrite           overwrite existing outputs instead of incrementing

License

Copyright (C) 2022 Wildlife Conservation Society The files in this repository are part of the task framework for calculating Human Impact Index and Species Conservation Landscapes (https://github.com/SpeciesConservationLandscapes⁠) and are released under the GPL license: https://www.gnu.org/licenses/#GPL⁠ See LICENSE for details.