Preserving Spatial Correlation in Network Water Demands

Demands for water in a municipal pipe network can exhibit strong spatial correlation owing to similar daily schedules among residential users and other consumers. This paper shows how to specify a diurnal demand pattern to preserve a desired degree of cross correlation among network water users. The influence of temporal averaging and spatial aggregation on the level of cross correlation among nodal water demands is clarified. The effect of spatially correlated network demands on the magnitude of the pressure head and on the migration of a contaminant intrusion is examined. For the range of conditions explored here, results show the correlation between water demands does not have a significant effect on the average nodal pressure head in a system with conventionally sized pipes. However, highly correlated water demands lead to larger variations of nodal pressure head, which result in larger probabilities of pressure failure. In addition, the average pressure head at any time ultimately depends on the parent pattern provided.