2:45 PM - 3:00 PM
[AAS08-05] Multiple scale structure of rainfall and human distributions in monsoon Asia
Keywords:monsoon Asia, rainfall distribution, population density
Yamanaka et al. (JpGU-AGU2020 U24-01) show that Japanese 47 prefectures and Indonesian 34 provinces have COVID-19 total cases dependent on the population density, and suggest similar human damages also for natural disasters. Here I show such domestic population maldistribution, more exactly speaking differential population densities among administrative areas in monsoon Asia have a universal "law" originated from rainfalls (determining rice productivity) over river basins.
Japanese and Indonesian administrative districts have “laws” of population∝(population density)1/2 (Figure) and area∝(population density)–1/2. These satisfy population density= population/density, and population × density≒constant (≒1011 people km2), implying the narrower the more crowded. Those districts have histories longer than thousand years and originated from small kingdoms based on river basins (bordered by dividing mountains or river. They have been unified gradually to form larger territories (mainly rice-agricultural areas) with concentrating populations at bigger capitals, and become finally the whole national territories since about four hundred years ago.
In the rice-agricultural areas, on one hand, the population∝rice paddy-field area∝river-basin total rainwater (volume), or population density∝annual rainfall (mm), which has been confirmed based on coastal concentrations of annual rainfall (Ogino et al., 2016, 2017) and population. Therefore the regional population∝annual rainfall × area, and annual rainfall∝1/area2, namely the broader the drier (a quarter rainfall makes a double area). On the other hand, rainfall extremes∝period1/2 (Jennings, 1950; Yoshino, 1960; Ninomiya and Sakakibara, 1979; Matsumoto, 1993; Kiguch and Oki, 2010, among others), therefore rainfall intensity (mm/observational period)∝(observational period)1/2. Since meteorological spatial scale∝temporal scale, we have (rainfall extreme)2×are≒constant, and annual rainfall∝(rainfall extreme)4. If the annual rainfall is doubled, the rainfall extreme becomes 21/4≒1.2 times, that is, increased 20%.
For the pandemic, the infection ratio∝(mean personal distance)–1∝(population density)1/2, and the total cases = population×infection ratio∝population density∝population2. Similarly, for the disasters dependent on population density, we have total sufferers∝population2. Therefore, if the magnitude is enlarged, medical/disaster prevention systems∝population become insufficient. The population concentration (city construction) with centralization originating from ancient rice-based autocracy is inappropriate for the population-proportional (equality-based) democracy.
Japanese and Indonesian administrative districts have “laws” of population∝(population density)1/2 (Figure) and area∝(population density)–1/2. These satisfy population density= population/density, and population × density≒constant (≒1011 people km2), implying the narrower the more crowded. Those districts have histories longer than thousand years and originated from small kingdoms based on river basins (bordered by dividing mountains or river. They have been unified gradually to form larger territories (mainly rice-agricultural areas) with concentrating populations at bigger capitals, and become finally the whole national territories since about four hundred years ago.
In the rice-agricultural areas, on one hand, the population∝rice paddy-field area∝river-basin total rainwater (volume), or population density∝annual rainfall (mm), which has been confirmed based on coastal concentrations of annual rainfall (Ogino et al., 2016, 2017) and population. Therefore the regional population∝annual rainfall × area, and annual rainfall∝1/area2, namely the broader the drier (a quarter rainfall makes a double area). On the other hand, rainfall extremes∝period1/2 (Jennings, 1950; Yoshino, 1960; Ninomiya and Sakakibara, 1979; Matsumoto, 1993; Kiguch and Oki, 2010, among others), therefore rainfall intensity (mm/observational period)∝(observational period)1/2. Since meteorological spatial scale∝temporal scale, we have (rainfall extreme)2×are≒constant, and annual rainfall∝(rainfall extreme)4. If the annual rainfall is doubled, the rainfall extreme becomes 21/4≒1.2 times, that is, increased 20%.
For the pandemic, the infection ratio∝(mean personal distance)–1∝(population density)1/2, and the total cases = population×infection ratio∝population density∝population2. Similarly, for the disasters dependent on population density, we have total sufferers∝population2. Therefore, if the magnitude is enlarged, medical/disaster prevention systems∝population become insufficient. The population concentration (city construction) with centralization originating from ancient rice-based autocracy is inappropriate for the population-proportional (equality-based) democracy.