1. Hydraulic Design of Reservoir in Permeable Pavement for Mitigating Urban Stormwater

Green infrastructure stormwater control measures, such as permeable pavement systems, are common practices used for controlling stormwater runoff in a developed country. This paper focus on the permeable pavement as a measure of stormwater mitigation in urban area. A hydraulic design aspect of reservoir stone layer is offered along with solution for the study area. Hydraulic design of the stone reservoir storage area includes depth of reservoir layer, drawdown time and storage volume. The depth of stone reservoir is calculated using the minimum depth approach for a permeable pavement of a given specific region. Rajendra Nagar Patna as study area is considered for design calculation. The depth of reservoir layer is 471 mm corresponding to last three years average annual precipitation of 120 mm. This will store water 7963 m³ with draw down time of 57 h. Soil beneath reservoir layer having low-infiltration rate, hence required additional measure like drain pipe. In addition, proper maintenance is needed to keep pores of the pavement surface remain open. According to researchers, cost of the permeable pavement is 15–80% less than the other stormwater management measures. Increasing the amount of stormwater in-filtered can result in lower stream flow levels after storm events. Permeable pavement can be used to substantially reduce the volume of stormwater runoff.