A Simple Method for Designing Infiltration Low Impact Development Techniques Considering Effects of Urbanization and Climate Change

Marcus N. Gomes Jr. , Cesar A. F. do Lago, Eduardo M. Mendiondo

Infiltration-focused low-impact development (LID) solutions aim to gradually absorb surface runoff, playing a critical role in reducing both peak flow rates and runoff volumes. These systems are commonly designed with specific surface areas and controlled ponding depths to provide sufficient storage capacity that counteracts the increased runoff resulting from urban expansion. Nevertheless, arbitrarily selecting the ponding depth---without systematic optimization---may lead to designs that either lack sufficient storage or utilize unnecessary space. This work presents MoDOBR, an optimized sizing framework specifically developed for retention systems. The methodology is demonstrated through four practical examples. A key aspect of the proposed approach is ensuring that the design ponding depth closely aligns with the required storage volume to manage excess runoff, particularly under conditions where infiltration pathways and underdrainage may become clogged or ineffective. The model dynamically solves the mass balance at both the system’s surface and at the interface with the saturated soil zone. The application of MoDOBR across various case studies, including a soil sensitivity assessment, reveals that sandy soils typically require LID installations covering about 2.9% of the drainage area, while clayey soils may demand up to 50% coverage when accounting for runoff from a storm with a 5-year return period.