Water-sensitive urban planning: Modeling on-site infiltration

A hydrological micromodel was developed and applied to a neighborhood typic al of urban development on Israel's coastal plain, over the phreatic coasta l aquifer. The model was used for analyzing the effects of urban developmen t on infiltration and runoff, and for evaluating a number of practices desi gned to enhance on-site infiltration. The effect of spatial resolution in t he model on computed results was investigated. It was shown that for the ra nge of data examined, simulation at the micro- (residential lot) level can be extrapolated to the neighborhood scale, by adding the responses of the i ndividual microunits. Simulations by the hydrological micromodel showed tha t 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 pl anning parameters was generalized in functional relations that can be used to assess the effectiveness of measures for increasing infiltration and red ucing runoff. This work was part of an effort to develop, test, and recomme nd policies and practices for water-sensitive urban planning for protecting water resources.