Estimation of the SDGs indicator 11.3.1 in Japan
Background
SDGs indicator 11.3.1, "Ratio of land consumption rate to population growth rate," assesses progress toward Target 11.3: "By 2030, enhance inclusive and sustainable urbanization and capacity for participatory, integrated, and sustainable human settlement planning and management in all countries."
Earth observation data is anticipated to play a key role in calculating this indicator, and the custodian agency, the United Nations Human Settlements Programme (UN-Habitat), has developed and published the methodology. This methodology enables governments to calculate the indicator, allowing for adaptations to each country’s specific conditions for optimal application.
In Japan, the Ministry of Internal Affairs and Communications has established the Working Group on Validation of Use of Observation Data under the Industry-Government-Academia Partnership for the Promotion of Big Data Utilization. This working group, in collaboration with relevant ministries and experts, examined the indicator using satellite data from JAXA and other Japan-specific datasets.
This article details the process of calculating and visualizing the Land Consumption Rate to Population Growth Rate (LCRPGR) in Japan using satellite data.
Definition of Indicator 11.3.1
Indicator 11.3.1 is defined as the ratio of the Land Consumption Rate (LCR) to the Population Growth Rate (PGR).
The Population Growth Rate (PGR) is calculated as the natural logarithm of the ratio of the population at the end of the target period to the population at the beginning of that period, divided by the number of years within that period.
Similarly, the Land Consumption Rate (LCR) is calculated by determining the change in the land area occupied by urban spaces during the target period, expressed as a ratio to the land area occupied at the beginning of that period, also divided by the number of years.
Pop t is the total population of the target region in the first or the past year, Pop t+n is the total population of the target region in the last or the present year, Urb t is the total area of city/urban area in the first or the past year, Urb t+n is the total area of city/urban area in the last or the present year and y is the number of years in the measurement period for population and the area of the region.
Thus, Indicator 11.3.1 (LCRPGR) can be derived using the following formula.
Procedures
To calculate and visualize LCRPGR we first determined the Population Growth Rate (PGR) and Land Consumption Rate (LCR) separately before calculating LCRPGR.
Trends by Ordinance-Designated City
To compare trends across Japan’s major cities, we calculated the indicators for 20 ordinance-designated cities, representing each region.
For the PGR calculations, we used administrative boundary statistics from the following population data sources:
Comparison of Changes in LCRPGR, LCR, and PGR by City
Analyzing changes in LCRPGR, LCR, and PGR across cities revealed distinct trends. Some examples are highlighted below:
Kyoto: The LCR shifted from an increasing to a decreasing trend, and the PGR also moved from increasing to decreasing. From 2010 to 2015, both land consumption and population grew; however, from 2015 to 2020, both began to decline.
Tokyo Surrounding Cities (Saitama, Kawasaki, Yokohama): The LCR transitioned from an increasing to a decreasing trend, while the PGR continued to rise. This pattern suggests ongoing population growth, even as the pace of land consumption expansion has slowed.
Conclusion
This analysis demonstrates that Japan-specific data and indicators, corrected with appropriate error evaluation, can effectively capture population dynamics and land consumption trends within any administrative region or economic area.
A comparison of approximate indicators calculated on a grid square basis versus an administrative area basis shows that the two methods yield comparable results. This suggests that approximate indicators are valuable for expanding the calculation scope and estimating these metrics.
