Nature Based Solutions for Sustainable Urban Storm Water Management in Global South: A Short Review

Rapid urbanization in the Global South exacerbates urban water management challenges such as urban flooding and water pollution, rendering many areas water-insecure. Our reliance on grey infrastructures to combat these water management challenges is not sustainable in the long run, due to which a better alternative must be sought. Nature-based Solution (NBS) promote ecosystem services and enhance climate resiliency along with flood control and improvement of water quality by utilizing natural elements including green spaces and water bodies within the urban environment. In the past few decades, NBS have been adapted for urban drainage in Global North and evolved by means of various terms based on geographic location, practices and applications. Some of these well-known terms include Low Impact Development (LIDs), Sustainable Urban Drainage Systems (SUDS), Water Sensitive Urban Design (WSUD) and Best Management Practices (BMPs). The transition towards a resilient and sustainable environment has been made possible through the application of NBS. Recently, countries in the Global South such as Singapore, Malaysia, Vietnam, and Thailand are trying to alter urban storm water management strategies through conversion of grey infrastructure to green infrastructure by employing various NBS techniques. The findings of this study show how NBS has influenced the Global South’s urban water management.

Development of a bio-retention system for urban storm water management

Urban stormwater that flows through all the manmade structures contains high levels of BOD TSS, orthophosphate, surfactants etc. It raises concerns of water quality in the receiving natural water courses. Bio-retention is one of the prominent methods of stormwater management for the removal of contaminants from stormwater. In this esxperimental study, a column containing mulch, blast furnace slag, sand, silt etc. was used to assess the removal of suspended solids and nutrients (nitrate and phosphate) from stormwater. The tests were conducted with a flow through period of 3, 7 and 15 days. Removal efficiency of 80% total suspended solids for 15 day, 60% nitrate for 7 days and 70% phosphorous for 3 and 7 days was observed through the column. pH variation was found to be insignificant in the range of 6-7.5.

Simulation of Urban Storm Water Runoff Control Based on Big Data

The acceleration of urbanization has brought about rapid economic development, but at the same time, it has also brought some damage to the ecological environment. The proportion of hardened area of the ground is higher and higher, and the rainwater runoff pollution caused by rainfall is more and more serious. In order to follow the sustainable development strategy, and for the more stable and high-speed economic development, the control of rainwater runoff pollution is urgent. The purpose of this paper is to simulate the urban storm water runoff control and find the most suitable scheme for storm water runoff pollution control. Because the simulation of SWMM is more accurate than other models, it can directly reflect the situation of rainwater runoff pollution, so the model selected for rainwater runoff in this paper is SWMM, and then build the model, through the collection and collation of the basic data of the study area, the generalization of the sub catchment area and drainage network is completed. Through the analysis of the characteristics of the study area, the rainwater garden and permeable pavement are determined as the scheme to control the rainwater runoff in the study area. Finally, the SWMM model is used to simulate the control effect of rainwater garden and pervious pavement on rainwater runoff pollution control. The experimental results show that the storm water garden can effectively control the impact of SS scouring effect on the environment, significantly reduce the discharge of SS, and significantly reduce the peak concentration of SS, and its ability to control SS increases with the thickness of the surface plant layer. The control ability of rain permeable brick pavement to SS increases with the increase of surface porosity, that is, the control effect of SS is the best when the porosity is 20%.

AN ANALYSIS ON THE EFFICIENCY OF GREEN ROOF IN MANAGING URBAN STORMWATER RUNOFF

Modernization has created new impervious urban landscape contributed to major catastrophe. Urban drainage system incapable to convey the excess rainwater resulting in flash flood due to heavy rainfall. The combination of green roof on building have tremendously proved to control stormwater efficiently. This study is conducted to review the efficiency of intensive and extensive green roof in reducing urban storm water runoff. This study identifies characteristic of green roof that contributes to lessening urban storm water runoff. Data was collected based on rigorous literature reviews and analyzed using meta-analysis. Overall, findings revealed intensive green roof performed better in reducing storm water runoff compared to extensive green roof. Green roof performance increases as the depth of substrate increased. Origanum and Sedum plants are both highly effective for intensive and extensive green roofs. The performance of green roof reduces as degree of roof slope increased.

Isotope hydrology and water sources in a heavily urbanised stream

Complex networks of both natural and engineered flow paths control the hydrology of streams in major cities through spatio-temporal variations in connection and disconnection of water sources. We used spatially extensive and temporally intensive sampling of water stable isotopes to disentangle the hydrological sources of the heavily urbanized Panke catchment (≈ 220 km²) in the north of Berlin, Germany. The isotopic data enabled us to partition stream water sources across the catchment using a Bayesian mixing analysis. The upper part of the catchment streamflow here is dominated by groundwater from gravel aquifers underlying surrounding agricultural land. In dry summer periods, streamflow becomes intermittent; possibly as a result of local groundwater abstractions. Urban storm drainage is also an important part of runoff generation, dominating the responses to precipitation events. Although this dramatically changes the isotopic composition of the stream, it only accounts for 10-15% of annual streamflow. Moving downstream, subtle changes in sources and isotope signatures occur as catchment characteristic vary and the stream is affected by different tributary inflows. However, effluent from a wastewater treatment plant (WWTP) serving 700,000 people dominates the stream in the lower catchment where urbanisation effects are more dramatic. The associated increase in sealed surfaces downstream also reduces the relative contribution of groundwater to streamflow. The volume and isotopic composition of storm runoff is again dominated by urban drainage. As a result, only about 10% of annual runoff in the lower catchment comes from urban storm drains. The study shows the potential of stable water isotopes as inexpensive tracers in urban catchments that can provide a more integrated understanding of the complex hydrology of major cities. This offers an important evidence base for guiding the plans to develop and re-develop urban catchments to protect, restore and enhance the ecological and amenity value of these important resources.

Method for estimating the incoming flow of surface runoff in the urban storm sewer

Согласно положениям Водного кодекса Российской Федерации № 74-ФЗ и Федерального закона № 416-ФЗ «О водоснабжении и водоотведении», все предприятия, эксплуатирующие централизованные системы водоотведения, в том числе системы отведения поверхностных сточных вод, должны в установленном порядке вести коммерческий учет объема принятых в эксплуатируемые системы сточных вод, а также объема стоков, отведенных в водные объекты. Приведена методика учета объемов поступления поверхностных сточных вод в централизованные системы поселений и в водные объекты города, а также особенности ее применения с использованием расчетных методов. Показано, что реализация обоснованных методов учета объемов сброса поверхностных сточных вод с территории города в водные объекты обеспечит достоверность и легитимность расчетов объемов принятых (отведенных) поверхностных сточных вод при осуществлении государственного мониторинга водных объектов, определении платежной базы за негативное воздействие на окружающую среду и определении тарифов для абонентов сети. According to the provisions of the Water Code of the Russian Federation No. 74-FZ and Federal Law No. 416-FZ «On Water Supply and Wastewater Disposal», all enterprises operating public wastewater disposal systems, including surface runoff drainage systems, shall, in accordance with the established procedure, keep a commercial record of the volume of wastewater received by the operated systems, as well as of the volume of wastewater discharged into water bodies. The method for accounting for the volume of surface runoff discharged into public systems of communities and into urban water bodies, as well as the specific features of applying the method with the use of calculations. It is shown that the implementation of justified methods for accounting for the volume of surface runoff discharged from urban territories into water bodies will ensure the reliability and legitimacy of the calculations of the volumes of received (removed) surface runoff in the process of the state monitoring of water bodies, determining the basis of charging for the negative environmental impact and setting tariffs for the customers using sewer network.