Low Impact Development Design Research Articles

Robustness analysis of storm water quality modelling with LID infrastructures from natural event-based field monitoring

Sponge city construction (SCC) in China, as a new concept and a practical application of low-impact development (LID), is gaining wide popularity. Modelling tools are widely used to evaluate the ecological benefits of SCC in stormwater pollution mitigation. However, the understanding of the robustness of water quality modelling with different LID design options is still limited due to the paucity of water quality data as well as the high cost of water quality data collection and model calibration. This study develops a new concept of ‘robustness’ measured by model calibration performances. It combines an automatic calibration technique with intensive field monitoring data to perform the robustness analysis of storm water quality modelling using the SWMM (Storm Water Management Model). One of the national pilot areas of SCC, Fenghuang Cheng, in Shenzhen, China, is selected as the study area. Five water quality variables (COD, NH3-N, TN, TP, and SS) and 13 types of LID/non-LID infrastructures are simulated using 37 rainfall events. The results show that the model performance is satisfactory for different water quality variables and LID types. Water quality modelling of greenbelts and rain gardens has the best performance, while the models of barrels and green roofs are not as robust as those of the other LID types. In urban runoff, three water quality parameters, namely, SS, TN and COD, are better captured by the SWMM models than NH3-N and TP. The modelling performance tends to be better under heavy rain and significant pollutant concentrations, denoting a potentially more stable and reliable design of infrastructures. This study helps to improve the current understanding of the feasibility and robustness of using the SWMM model in sponge city design.

A User-Friendly Software Package to Develop Storm Water Management Model (SWMM) Inputs and Suggest Low Impact Development Scenarios

Increases in imperviousness due to urbanization and industrialization increases stormwater runoff and nonpoint source pollution. Approaches reducing these hydrological impacts include low impact development (LID) methods. Various methods have been developed and applied to date, and an evaluation of stormwater runoff and a reduction of non-point source pollution has been conducted. The Storm Water Management Model (SWMM) is capable of simulating various LID approaches, although selecting and implementing a suitable method for a specific target area, when considering the cost of various low impact development approaches, requires significant time and effort. A software program called Storm Water Management Model–low impact development design program (SWMM-ING), that can be optimally applied to deal with the cost of low impact development methods, was developed in this study. For SWMM-ING, an optimization process was conducted for low impact development, which can reduce stormwater runoff by 10%, suspended solid by 15%, and total phosphorus by 15%. The spatial arrangement and the area of the permeable pavement, bioretention cells, infiltration trenches, and green roofs were determined. Because SWMM-ING has a user-friendly graphical interface, and the optimization process of the low impact development approach is simple and straightforward, it has the advantage of not requiring specialized knowledge.

Evaluation of the Main Function of Low Impact Development Based on Rainfall Events

Low Impact Development (LID) is one of the sustainable approaches to urban stormwater management in areas with rapid urbanization. Although LID has been shown to have a positive effect in flood reduction, the hydrological balance regulation effect of LID under a variety of rainfall events is not fully understood. In this study, we assessed the hydrological efficiency of LID at two residential–commercial mixed sites in Korea to investigate the main function of LID in terms of diverse rainfall characteristics. Storm Water Management Model (SWMM) was constructed to simulate the hydrological process numerical simulations in the pre-development, post-development and LID design scenarios, respectively. The model was calibrated and validated by using five observed rainfall–runoff events. Then, four single and four multiple LID practices (LIDs) were used to estimate their effectiveness under seven different designed rainfall events. The results indicate that LIDs substantially influence the hydrology cycle system, while the regulating effect varies with rainfall amounts. The efficiency of LIDs in flood reduction is proved to be more effective during lower storm events. However, LIDs should be designed to primarily prioritize the restoration of hydrological balance when the rainfall return period is longer.

Design of low impact development in the urban context considering hydrological performance and life‐cycle cost

AbstractThe pressures on water system are increasing in cities. Rapid urbanisation caused by booming population leads to more impervious area and less infiltration, with the consequence of larger runoff volume and higher flood risk. Launched in 2014, the low impact development (LID), an important part of Sponge City in China initiative, invests in projects that aim to restore the water cycle in the urban area. A comprehensive understanding of the performance of LID measures at watershed scale under different rainfall scenarios and life cycle costs is necessary. The objectives of this study are to assess the hydrological performance and to identify the optimal LID design by using SWMM model and life cycle cost (LCC) method. This study found that LID practices, including bioretention, grass swale, and permeable pavement, showed good performance on urban storm mitigation at watershed scale under different rainfall scenarios. Furthermore, the rates of surface runoff reduction were largely insusceptible to the change of rainfall volume and duration. Regarding the cost‐effectiveness, the priority was grass swale > bioretention > permeable pavement in the study area. The optimal LID scenario was the combination of these three types of LID. The proposed approach can help the decision‐makers to determine the preferable LID plan suitable for the local communities.

On the Effectiveness of LID Infrastructures for the Attenuation of Urban Flooding at the Catchment Scale

AbstractThe efficacy of low‐impact development (LID) toward the attenuation of urban flood at the catchment scale is still an unsolved question. This work aims at providing insight into the effectiveness of LID at the catchment scale by a simple hydrological modeling approach that allows for an analytical solution. The paper focuses on LID design, investigating the peak discharge at the catchment outlet as a function of the return period of the rainfall event under unaltered and retrofitted conditions. The model captures the most important effects of LID on flood, that is, the temporal shift and attenuation of water discharge and the decrease of water volume conveyed by the drainage network due to increased hydrological losses. It is found that LID is likely more effective in reducing peak discharge at the local scale, while the effectiveness decreases with increasing catchment size. For some configurations, for example, when retrofit is performed in downstream areas, closer to the outlet, LID may even worsen the flood risk. The effectiveness of LID depends on the combination of several factors, including the fractional area covered by the LID infrastructures, their distribution within the catchment, and their hydraulic properties, as compared with the general hydraulic features of the catchment (network dispersion, detention, lag time, etc.). As a consequence, the LID design should be carried out considering all the relevant scales of the problem, from the local one, at which the LID infrastructure is implemented, to the catchment scale, and the discharge at the outlet in particular, in a comprehensive perspective.

Optimal Planning of Low-Impact Development for TSS Control in the Upper Area of the Cau Bay River Basin, Vietnam

Recently, an increase in impervious area induced by the process of urbanization has significantly affected the quantity and quality of urban surface runoff. Among the pollutants of the storm flow, total suspended solids (TSS) are an extremely important cause of water quality deterioration. This paper aims to use the integrated nondominated sorting genetic algorithm (NSGA II)–Storm Water Management Model (SWMM) method to find optimal Low-Impact Development (LID) plans which ensure maximum TSS load reduction and minimum total relative cost. Green roofs, permeable pavements, and tree boxes with fixed parameters and unit costs were considered for seeking optimal planning alternatives in the Cau Bay river basin. The optimization process yielded a cost–effectiveness curve, which relates cost of LID implementation with its corresponding TSS reduction efficiencies. The advantage of the optimization approach was clarified when, with a defined cost of LID implementation, there was a significant difference in TSS reduction efficiencies between the optimal and non-optimal alternatives. The increase in return periods of rainfall patterns not only resulted in a reduction in the TSS removal efficiencies of LID practices at the outfall of the study area, but also spatially changed in terms of the TSS removal efficiencies of the sub-catchments. The return period of the rainfall patterns utilized for LID design should not exceed 2 years. The simulation–multi-optimization approach facilitates integration of LID practice plans into the urban infrastructure master plans in Vietnam.

The model of low impact development of a sponge airport: a case study of Beijing Daxing International Airport

Abstract A sponge airport is a new concept of airport stormwater management, which can effectively relieve airport flooding and promote the usage of rainwater resources, often including the application of low impact development (LID) facilities. Although many airports in China have been chosen to implement sponge airport construction, there is a lack of quantitative evaluation on the effect of LID facilities. This paper takes Beijing Daxing International Airport as a case study and develops a comprehensive evaluation on the effect of LID facilities using the storm water management model (SWMM). The performance of four LID design scenarios with different locations and sizes of the rain barrel, the vegetative swale, the green roof, and the storage tank were analyzed. After LID, the water depth of J7 reduces from 0.6 m to 0.2 m, and duration of accumulated water reduces from 5 hours to 2.5 hours. The water depth of J17 reduces from 0.5 m to 0.1 m, and duration of accumulated water reduces from 2 hours to 15 minutes. The capacity of conduits has been greatly improved (Link 7 and Link 17). The application of LID facilities greatly improves rainwater removal capacity and effectively alleviates the waterlogging risk in the study area.

Converting traditional landscape into resilient landscape in Zhenjiang City to manage stormwater runoff: A case study

Since the beginning of low impact development (LID) introduced into China, the aesthetic perspective has been a big issue in LID practices. Many landscape architects viewed LIDs as a contradiction to the traditional landscape design. Therefore, a significant challenge in Sponge City construction in China is to communicate with landscape architects understanding the importance of managing stormwater runoff and pollutant removal close to the source. In this paper, we presented a framework developed for civil engineers and landscape architects working together to guide the LID or green infrastructure design. We presented a case study in China using this guideline to build a resilient landscape with aesthetics. It illustrated that the beautiful landscape could be integrated into local LID and regional green stormwater infrastructures for flood mitigation and high pollution load removal.

An Integrated Fuzzy Simulation-Optimization Model for Supporting Low Impact Development Design under Uncertainty

Seeking cost-effective design of urban hydrological facilities and drainage systems is an important task for many city planners. However, such a process has always been complicated with intrinsic uncertainties. This work presented an integrated fuzzy simulation-optimization model (FSOM) for supporting Low Impact Development (LID) design under model uncertainties. Various LID implementation schemes involving green roof, bio-retention cell, and permeable pavement were simulated through an urban hydrological model. Three model parameters were assumed as fuzzy sets. In a case study, fuzzy simulation (FS) and genetic algorithm (GA) were employed to search the optimal schemes of LIDs under various confidence levels of satisfying flood control constraints. Comparison of FSOM to traditional deterministic and stochastic models were also carried out. It was shown that FSOM could offer a flexible way of defining and assessing uncertainties associated with hydrological modeling and generate solutions that were comparable to those from either deterministic or stochastic models. However, FSOM also showed limitation of high computational requirement.

저영향개발 통합 계획 체계-다기능 성능 목표 구현 회귀적 계획 프로세스

Purpose and Method: The aim of this study is to suggest an integrated planning system for Low-Impact Development (LID) with recursive planning process achieving multi-functional objectives. LID can deliver multi-functional performance objectives including surface water management, non-point pollution management, amenity and biodiversity. Integrated LID planning system is proposed based on comparative analysis of six guidelines. Result: The phase of integrated LID design has 4 phases. The first phase is setting of the multi-functional objectives. The multi-functional objectives include performance standards and design criteria on surface water management, non-point pollution management, amenity, biodiversity. The second phase is composing the management train with LID components selected and placed. The third phase is balanced size of management train considering plot properties. The forth phase is refining dimension of each component. Each phase of LID design should include recursive planning process on performance standards and design criteria.

Model-Based Selection of Cost-Effective Low Impact Development Strategies to Control Water Balance

Urbanization induces an increase of runoff volume and decrease of evapotranspiration and groundwater recharge. Low impact development (LID) strategies aim to mitigate these adverse impacts. Hydrologic simulation is a reasonable option to assess the LID performance with respect to the water balance and is applicable to planning purposes. Current LID design approaches are based on design storm events and focus on the runoff volume and peak, neglecting evapotranspiration and groundwater recharge. This contribution presents a model-based design approach for the selection of cost-effective LID strategies. The method is based on monitored precipitation time series and considers the complete water balance and life-cycle-costs, as well as the demand for land. The efficiency of LID strategies (ELID) is introduced as an evaluation measure which also accounts for emphasizing different goals. The results show that there exist several pareto-optimal LID strategies providing a reasonable basis for decision-making. Additionally, the application of LID treatment trains emerges as an option of high potential.

The Influence of Soil Stochastic Heterogeneity and Facility Dimensions on Stormwater Infiltration Facilities Performance

The progressive increase of impervious surfaces induced by urbanization altered significantly the natural hydrological cycle of urban catchments. To face the need of more sustainable and effective solutions for stormwater management and planning, Low Impact Development (LID) practices have been frequently proposed to support existing urban drainage systems. Among LID infrastructures, design and management of stormwater infiltration facilities are still characterised by a high degree of uncertainty. Since the stochastic heterogeneity of the soil may affect significantly their hydraulic performance, it is crucial to understand whether it should be accounted for in the design process. To this aim, numerical experiments under transient variably water saturated conditions were performed. Four infiltration facilities of different bottom length subjected to the same spatial variability of the intrinsic permeability field were considered. Simulations showed that the effects of stochastic heterogeneity on the hydraulic performance are dependent on the dimensions of the facility and on the correlation lengths of the intrinsic permeability field. These effects may potentially undermine the capacity to capture stormwater. To be reduced, the bottom dimensions of the facility should be higher than the horizontal correlation lengths of the intrinsic permeability field. Most strikingly, whether the stochastic heterogeneity is considered or not, the volume infiltrated through the bottom follows an increasing power law with increasing bottom length, while the average infiltration rate at the bottom follows a decaying power law.

Runoff Capture Methods Developed for Stormwater Low-Impact Development Designs

AbstractEfforts under stormwater best management practices have led to low-impact development (LID) concepts for innovative stormwater designs. The key issue involved in the revolution of stormwate...

Storm Water Management of Low Impact Development in Urban Areas Based on SWMM

LID (low impact development) is the storm management technique designed for controlling runoff in urban areas, which can be used to solve urban flooding disasters. Taking Sucheng District of Suqian City, Jiangsu Province, China as an example, this project used SWMM (storm water management model) to study the effect of four different types of LID scenarios (① no LID technique, ② LID technique based on infiltration, ③ LID technique based on water storage, ④ LID technique based on the combination of infiltration and water storage) on urban flooding under different rainfall patterns. For the whole study area, the results show that infiltration facilities have the greater reduction rate of surface runoff compared with storage facilities. The combined model (infiltration + storage) works best in the reduction of peak flow and flood volume, with the maximum reduction rate of peak flow (32.5%), and the maximum reduction rate of flood volume (31.8%). For local nodes, infiltration facilities and water storage facilities have different effects. Infiltration facilities significantly reduce runoff of node 47, the reduction rate of ponding time ranges from 73.1% to 54.5%, while water storage facilities have no effects on it. Storage facilities significantly reduce runoff of node 52, the reduction rate of ponding time is 100%, while infiltration facilities have no effects on it. Under all the LID designs, runoff reduction gradually increases with the increasing rainfall amount, and peak reduction becomes stable when rainfall amount reaches about 81.8 mm. In general, the combined model (infiltration + storage) performs better than any other scenarios in runoff reduction. The research shows that LID facilities can greatly mitigate flood, thus the urban flooding disasters caused by extreme rainstorms can be prevented.

An assessment of the hydrologic effectiveness of low impact development (LID) practices for managing runoff with different objectives

This study represents an approach to assess the hydrologic effectiveness of low impact development (LID) practices based on the expected runoff process with different objectives and land utilization. The proposed approach is to simulate runoff hydrograph rather than several indices (e.g., runoff initiation, peak flow, and runoff volume) to avoid the uncertainties under a certain rainfall scenario. A rainfall-runoff model of a residential district in China, constructed based on the stormwater management model (SWMM), is auto-calibrated (validated) based on 12 (25) observed rainfall and runoff events using model-independent parameter estimation (PEST). The priority sites and parameters for LID practices for different objectives are auto-calculated using PEST based on the calibrated model and different expected runoff processes. The expected runoff processes are simulated from the calibrated model with four impervious cover scenarios corresponding to 5-year, 2-h duration design storm. The study illustrates that (i) the proposed approach can auto-optimize runoff manage strategies based on LID practices and land; (ii) the design parameters of LID practices can be auto-calculated and that simulated runoff processes are in near perfect agreement with expected runoff processes; (iii) this approach can auto-optimize any specific parameters of the SWMM and LID practices without changing those determined parameters. Our simple, but quantitative, approach for identifying potential LID sites and design parameters based on land can better inform the hydrologic effectiveness of LID practices for managing runoff.

Comprehensive performance evaluation of LID practices for the sponge city construction: A case study in Guangxi, China

Sponge city construction is a new concept of urban stormwater management, which can effectively relieve urban flooding, reduce non-point source pollution, and promote the usage of rainwater resources, often including the application of Low Impact Development (LID) techniques. Although 30 cities in China have been chosen to implement sponge city construction, there is a lack of a quantitative evaluation method to evaluate the environmental, economic, and social benefits of LID practices. This paper develops a comprehensive evaluation system to quantify the benefits of different combinations of LID units using the Storm Water Management Model (SWMM) and the Analytical Hierarchy Process (AHP) method. The performance of five LID design scenarios with different locations and sizes of the bio-retention facility, the grassed swale, the sunken green space, the permeable pavement, and the storage tank were analyzed for a sports center project in Guangxi, China. Results indicated that the green scenario that contains 34.5% of bio-retention facilities and 46.0% of sunken green spaces had the best comprehensive performance regarding meeting the requirements of 75% annual total runoff reduction and the attainment of good operation performance, rainwater utilization, landscape promotion, and ecological service functions, mainly because they are micro-scale and decentralized facilities that can manage stormwater at the source through the natural process. The optimal scenario was adopted to construct the project, and the proposed evaluation system can also be applied to optimal selection and performance effect evaluation of LID practices in other sponge city projects.

Evaluation of Effect of Urban Non-point Source Pollution Control on Porous Asphalt-Bio-retention Combined Roads

Different combinations of low impact development (LID) technologies can be applied for control of urban non-point source pollution. There are currently few evaluations of urban non-point source pollution and pollution load reduction based on a combination of porous asphalt and bio-retention. Taking Shenzhen International Low Carbon City as an example, road-deposited sediments were collected prior to and after rainfall events. Runoff was monitored under six typical rainfall events, from porous asphalt and the inlet/outlet of bio-retention. Through analysis of changes in the process of "build-up-wash-off-transport" of pollutant loads, the average build-up of road-deposited sediments in the study area was found to be (15.80±3.79) g·m-2; the mass percentage of road-deposited sediments (size>250 μm) was approximately 65.14%. The average wash-off percentage of six different intensity rainfall events was 17.15%, and road-deposited sediments (size<105 μm) were carried by 62.71%-74.94%. The average pollution loads of surface runoff pollutants SS, TN, and TP were 2.02, 0.025, and 0.0013 g·m-2, respectively. The removal rates of SS, TN, and TP through porous asphalt under infiltration and filtration were 70.26%, 46.29%, and 19.27%, respectively. The secondary purification removal rates of runoff water in bio-retention were 85.25%, 20.22%, and 70.27%, respectively. Pollutant loads into Dingshan River totaled 0.08, 0.011, and 0.0003 g·m-2, representing 4.05%, 43.47%, and 24.39% of runoff. The combination thus had a significant effect on runoff purification. Through quantitative research on the formation of non-point source pollution, this paper provides a scientific basis for estimating pollution loads of urban non-point source pollution and evaluating the performance of LID projects. It makes suggestions for the popularization and application of LID and sponge city design in China.

Impacts of nonpoint source pollutants on microbial community in rain gardens

Low-impact development (LID) techniques are being applied to reduce non-point source (NPS) pollution which are generated from various land uses. Cost-effective LID design requires consideration of influent runoff properties as well as physical and ecological pollutant-removing mechanisms. However, current LID technology design has failed to reflect the different properties of influent water from various land uses, and the biological design factors in LID facilities causing low efficiency and difficulties in maintenance. This study was conducted to identify biological design factors by analyzing the impact of the pollutants included in influent runoff and physical environment on microbial growth in rain garden facilities applied to different land uses. The results showed that the non-point source pollutant loadings were about 1.5–3 times higher in the runoff from parking lots, which are frequently visited by automobiles than in roof runoff. Type of soil, chemical species, and chemical composition were assessed as internal environmental factors having significant impact on the phylum and the count of microorganisms in the facilities. The growth of Cyanobacteria, Streptophyta, Chlorophyta, Bacillariophyta, and Xanthophyceae was good when there was appropriate water content in the soil, light, and sandy soil. Based on these results, the future design of rain garden facilities should be performed by considering a microorganism appropriate to the properties of the influent pollutants, determining appropriate water content, nutrient content and soil type, and choosing plants that contribute to microbial growth.

Decision Support System for the Design and Planning of Low-Impact Development Practices: The Case of Seoul

This study presented the conceptual framework of the water-management analysis module (WMAM) to derive effective physical specifications for the design and planning of low-impact development (LID) practices using the storm-water management model (SWMM). This decision-support system can be used for six LID types and has the following key capabilities: determining relevant LID design parameters within the SWMM that critically influence the hydrological cycle components using a simple sensitivity analysis and determining the best hydrological values for LID planning specification. This study analyzed a highly urbanized university campus as a case study to determine the design and planning specifications for an infiltration trench and permeable pavement. In addition, the performance of different LID practices during high-intensity rainfall events was compared. The results indicate that the WMAM can be very useful in determining many LID design and planning parameters.

Storm Water and Contamination Control Efficiency Evaluation for Construction of a Neighborhood Project Using Low Impact Development

Urban flooding and water pollution are urgent problems to be solved in urban development. The improvement of urban drainage and water quality in urban construction using ecological measures is an important research task. Low impact development (LID) is a new concept in soil and water conservation aimed at improving urban rainwater use and reducing non-point source pollution. This paper discusses the best management practices (BMPs) related to storm water and contamination control efficiency by comparing pre-development and post-development neighborhoods (both conventional and LID designs). The study area was Weatherford, Oklahoma, United States. The results showed that conventional design had the lowest total runoff but highest peak rate, infiltration trenches with rain barrels were more efficient than bioswales, and the use of LID design would reduce total runoff and peak rate significantly. However, LID design would increase construction and annual maintenance fees.