Are We Getting Closer to or Farther from Water? Human Population Distance to Water in the USA, 1790- 2010

Abstract:

Water is an attractive factor when people choose where to live. Early civilizations and modern cities primarily evolved around rivers. In early settlement periods, humans choose to locate close to rivers to satisfy their direct consumptive use as well as for navigation purposes. However, as population, wealth, and technical sophistication grow, the relative importance of proximity to rivers weakens, while agglomeration economic effects of historical established settlements and the indirect amenity value of water grow stronger. The reliance on locally available water decreases such that people are not constrained to live only in water-rich places. In this study, we examined the relationship between water resources (surface river networks and major aquifers) and the human population distribution in the conterminous United States from 1790-2010 to answer the following questions: 1) Are we getting closer to or farther from surface water? 2) How is the relative importance of groundwater changing over time? Our analysis indicated that humans have gotten farther from surface water, especially the arid regions, where the mean human population distance increased steadily from 13km to 26km from 1790 to 2010. However, groundwater became more attractive in determining human population distribution, indicated by rapid growth in population percentage living over major aquifers, especially after 1940. The latter trend is associated with rapid technological development. This study of the relationship between human population and water resources provides policy support for the sustainable management of surface water and groundwater resources.