Water-Sensitive Urban Planning: Modeling On-Site Infiltration

Abstract

A hydrological micromodel was developed and applied to a neighborhood typical of urban development on Israel's coastal plain, over the phreatic coastal aquifer. The model was used for analyzing the effects of urban development on infiltration and runoff, and for evaluating a number of practices designed to enhance on-site infiltration. The effect of spatial resolution in the model on computed results was investigated. It was shown that for the range of data examined, simulation at the micro- (residential lot) level can be extrapolated to the neighborhood scale, by adding the responses of the individual microunits. Simulations by the hydrological micromodel showed that connecting roof drains to a yard/garden, and allowing the runoff from the roof to infiltrate through an “infiltration strip” or infiltration trench of an appropriate size, can increase infiltration over a residential lot as much as 18% of the annual rainfall (depending on the soil conductivity and annual rainfall). The dependence of annual infiltration on physical and planning parameters was generalized in functional relations that can be used to assess the effectiveness of measures for increasing infiltration and reducing runoff. This work was part of an effort to develop, test, and recommend policies and practices for water-sensitive urban planning for protecting water resources.