scl3/task_hii_popdens repository overview

⁠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.