Integrative Assessment of Stormwater Infiltration Practices in Rapidly Urbanizing Cities: A Case of Lucknow City, India

The lack of strategic planning in stormwater management has made rapidly urbanizing cities more vulnerable to urban water issues than in the past. Low infiltration rates, increase in peak river discharge, and recurrence of urban floods and waterlogging are clear signs of unplanned rapid urbanization. As with many other low to middle-income countries, India depends on its conventional and centralized stormwater drains for managing stormwater runoff. However, in the absence of a robust stormwater management policy governed by the state, its impact trickles down to a municipal level and the negative outcome can be clearly observed through a failure of the drainage systems. This study examines the role of onsite and decentralized stormwater infiltration facilities, as successfully adopted by some higher income countries, under physical and social variability in the context of the metropolitan city of Lucknow, India. Considering the 2030 Master Plan of Lucknow city, this study investigated the physical viability of the infiltration facilities. Gridded ModClark rainfall-runoff modeling was carried out in Kukrail river basin, an important drainage basin of Lucknow city. The HEC-HMS model, inside the watershed modeling system (WMS), was used to simulate stormwater runoff for multiple scenarios of land use and rainfall intensities. With onsite infiltration facilities as part of land use measures, the peak discharge reduced in the range of 48% to 59%. Correlation analysis and multiple regression were applied to understand the rainfall-runoff relationship. Furthermore, the stormwater runoff drastically reduced with decentralized infiltration systems.

Regenerating Stormwater Infrastructure into Biophilic Urban Assets. Case Studies of a Sump Garden and a Sump Park in Western Australia

The main purpose of this paper is to demonstrate how the old modernist engineering technologies, such as single purpose stormwater infiltration basins, can be transformed into quality environments that integrate ecological and social functions and promote multiple sets of outcomes, including biodiversity restoration, water management, and cultural and recreational purposes, among other urban roles. Using the principles and theories of biophilic urbanism, regenerative design, and qualitative inquiry, this article analyzes and discusses the actors, drivers, strategies, constraints, and values motivating the stakeholders to reinvent Perth’s stormwater infrastructure through two local case studies. The “WGV sump park” was developed through a public-private partnership, including professional consultants with community input, and the “Green Swing sump garden” was an owner-builder community-driven project involving volunteers, who maintain it. The results of this research suggest that both projects are successful at managing stormwater in a way that creates multiple community and biodiversity benefits. Communities could gain improved access to nature, social interaction, health, and well-being if local governments support these alternative approaches to regenerate underutilized stormwater infrastructure by promoting biophilic interventions. Mainstreaming this design approach identified some issues that may arise during the implementation of this biophilic urban approach, and the paper suggests ways to enhance the wider delivery of regenerative and biophilic design into urban planning, involving volunteer delivery and maintenance for small scale projects and fully professional assessments for large scale projects.

Characterization of earthworms in an infiltration basin for maintaining water infiltration

<p>Infiltration basins are among the most spread techniques for managing stormwater. Infiltration basins allow the infiltration of stormwater, which prevents their piping towards treatment systems. However, stormwater contains loads of pollutants and suspended solids that accumulate at the surface of the basin and form a sedimentary layer. That sedimentary lay may clog the infiltration basin partially, thus reducing its bulk infiltration capability. Fortunately, plants and fauna colonize spontaneously this sedimentary layer, thus preventing complete clogging and restoring soils' infiltration functions. The knowledge of the effect on restoring the infiltration function requires properly characterize fauna, notably earthworms, with the aim to predict their impact on infiltration. Besides, earthworms, considered as ecosystem engineers, are known to be good candidates for integrating soil chemical pollution.</p><p>If earthworms have been intensively studied in natural and agricultural soil, very few studies have focused on the characterization of earthworms' communities in urban soils and, in particular, in infiltration basins. This study presents the description of earthworms sampled at several places over one infiltration basins. This basin receives the stormwater collected over an industrial peri-urban catchment. The infiltration basin has been functioning for more than two decades, thus, plants and fauna have colonized the surface related to water ponding at surface and water infiltration. The sampled places were selected to follow three specific water pathways at the surface. High population variability was measured with densities ranging from 0 to 300 earthworms per square meter with the presence of adults but also juveniles. But, only endogenic and epigeic functional groups were found. The characterization of abundance, age, and species over the sampled places was correlated to water content and sediment thickness, in addition to pollutant loads.</p><p>The results show that earthworms require given edaphic conditions (including thick enough sedimentary layer) to settle. We then expect most earthworms to colonize those specific places, increasing water infiltration punctually at these places. Put all together, our findings participate in the understanding of colonization of basin infiltration by organisms and their contribution to their primary function: infiltrating water.</p>