| Abstract: | Previous studies of correlation coefficients between paired observations using census, hydrologic, and remote sensing data abound. It is well established that bivariate relationships at coarser spatial resolutions are often stronger than at finer resolutions. No assessment as yet, however, corroborates this tendency with water resources variables. In this study, multiscale correlations between water use or water availability and population are presented in three river basins—the Missouri (United States), Danube (Europe), and Ganges (South Asia). High-resolution gridded data sets were obtained at 0.5° and resampled to fourteen different geographic scales to examine the effects of scale on the strength and trends of correlations. Correlation coefficients between most variable pairs increased at coarser scales. Smoothing fine-scale spatial patterns in the data at coarser scales is posited as a possible explanation. The increase was not often linear, however, nor was there always an increase. The Missouri Basin did not show a significant increase in correlations between water use and population with grid-cell size and nonlinear increases are evident in the Ganges Basin. |
