A Review of Recent Developments on Modeling Low Impact Development (LID) Technique

Within a wide range of best management practices for stormwater management in urban areas, there has been an increasing interest in source control measures. Source controls such as low-impact development (LID) techniques are potentially attractive as retrofit options for older developed areas that lack available land to implement conventional measures such as stormwater management ponds. Hence, distributed urban drainage models requiring detailed representation of developed drainage areas should be developed to accurately estimate the benefits that LIDs may provide. This study (1) presents a two-stage classification process on a high-resolution WorldView-2 image, and (2) demonstrates how to use the extracted land cover information in the subsequent hydrologic modelling and assessment of different LIDs’ performance. The proposed two-stage classification method achieved an overall accuracy of 80.6%, whereas a traditional pixel-based achieved 68.4% in classifying the same urban area into six land cover classes. From the classification results, the hydrologic properties of micro-subcatchments were imported in the United States Environmental Protection Agency Storm Water Management Model to assess the performance of LIDs. A reduction of run-off volume 18.2% and 37.1% was found with the implementation of porous pavement and bioretention, respectively, in a typical low-rise residential area located in the city of San Clemente, California, US. The study demonstrates the use of high-resolution remote sensing image to aid in evaluating LID retrofit options, and thus benefits in situations where detailed drainage area information is not available.

Effectiveness of low impact development practices in two urbanized watersheds: Retrofitting with rain barrel/cistern and porous pavement

Urbanization is one of the main important factors leading to urban flooding, which has caused major damage to the environment and society. Controlling urban flooding has become a new challenge for urban planners. There are many reasons of urban flooding in Delhi. It may occur due to increased urbanization, low rate of infiltration and poor infrastructure for storm water drainage network, improper drainage system. For controlling urban flooding, there is one of the control source solutions that help in reducing the urban flooding that is low impact development techniques. Low impact development (LID) is a new innovative technique for managing storm water at the source and helps to improve the water quality as well. It is most popular method which helps to reduce the hydrologic as well as water quality which effects by urbanization. The storm water management model (PCSWMM) is a widely used rainfall-runoff simulation model which has ability to model LID techniques. The LID used in this study is infiltration trench, green roof and rain water harvesting. The result obtained from the model (with LID) found to be satisfactory with the ground reality. In this present study, PCSWMM has been used for the first time for modelling storm water drains of the urban area (Delhi city, India), and the results obtained from simulation are in good consent with the observed data. Thus, the present study will help the flood managers to manage excess surface runoff during storm more efficiently in urban cities.

Low impact development (LID) techniques are increasingly used as a stormwater management strategy to maintain the hydrological conditions of developed areas and mitigate the negative consequences of stormwater runoff and nonpoint source pollution. Although LID techniques have been commonly used in moderate to humid areas, further information is needed on their effectiveness in semi-arid and arid regions. This study aims to examine and compare the effectiveness of LID techniques in arid and semi-arid climate conditions. First, a comprehensive study was conducted to rank LID techniques based on literature reviews while also incorporating different stakeholder priorities. Then, the city of Varamin, Tehran, Iran, was chosen as a low slope arid and semi-arid study region to assess the applicability of the best three high-ranked LID techniques using the storm water management model (SWMM). The results indicated that rainwater harvesting is the most effective technique in terms of stormwater quality and quantity management. The implementation of the rainwater harvesting technique across the case study is likely to decrease the average discharge, peak discharge, total volume, total runoff, and total suspended solids (TSS) by respectively 31.2%, 12.7%, 40.71%, 40.77% and 37.91%. Besides, rainwater tanks were projected to provide the water demands of home gardens during the five dry months, in addition to other domestic needs for water conservation objectives. The application of LID techniques in such water-limited regions can be useful for both stormwater management and water conservation.

Urban flooding poses a growing challenge, intensified by rapid urbanization and climate change, which strains traditional drainage systems. This study investigates the application of Low Impact Development (LID) techniques as a sustainable solution to enhance urban drainage system resilience. Using Gurugram, India, as a case study, the research evaluates the functional and structural resilience improvements achieved through LID implementation, alongside a Life Cycle Cost (LCC) analysis to assess cost-effectiveness.LID Performance Index (LPI) was employed to quantify the functional resilience – a  measure of system resilience under varying scenarios of urbanization and increased rainfall intensities. Structural resilience was analyzed by assessing reductions in vulnerable locations through one-at-a-time failure simulations. To effectively integrate the green roofs and rain gardens in the runoff management, the subcatchments with substantial impervious area and high runoff volume were designated as the potential subcatchments for LIDs’ application. The study examines four LID implementation scenarios, incorporating green roofs and rain gardens into 10% (S1), 25% (S2), 50% (S3), and 100% (S4) potential subcatchments.The finding reveals that incorporating LIDs into 10% of potential subcatchments (Scenario S1) enhances functional resilience by 21% and reduces vulnerable nodes by 8.7%. The corresponding Benefit-Cost Ratio (BCR) for Scenario S1 is 2.05 under a 5-year return period design storm, indicating its cost-effectiveness. While increasing LID coverage improves resilience, the cost-effectiveness diminishes due to higher implementation costs.The LCC analysis incorporates construction, maintenance, and salvage costs to evaluate the economic viability of LID practices. It highlights that LIDs are particularly effective for moderate storm events, with a noticeable decrease in effectiveness for extreme storms with higher return periods. The findings underscore the limitations of relying solely on LIDs for stormwater management, advocating for their integration with conventional drainage systems to address extreme scenarios effectively.The insights provided in study are valuable for urban planners, engineers, and policymakers aiming to develop sustainable and resilient urban drainage systems capable of mitigating urban flooding impacts.

LID (Low impact Development) has been widely promoted as a measure against urban flooding which has been recently increasing due to urbanization and climate change. However, studies that consider the combined effects of spatially distributing multiple LIDs simultaneously in an urban area of specific size as urban planning scenarios are few. In this study, two cases of past rainfall data (short duration and long duration heavy rainfall), are used to simulate the effects of 3 different urban planning scenarios of distributed LID (i.e. combined LIDs implementable at the 1) building-level, 2) in open spaces, and 3) combined implementation of both 1&2), in addition to simulating for separate implementation of each LID type using the Storm Water Management Model (SWMM). The results show that in the case of short duration heavy rainfall, all 3 LID scenarios provide a greater decrease in the rate of flood volume with comparison to the case of long duration heavy rainfall. This points to the fact that LIDs have a high potential to mitigate flood volumes resulting from short duration heavy rainfall - the type of rainfall which has become more frequent recently. Furthermore, the paper also organizes the LID types according to their implementability under different urban planning scenarios, and shows that such combined use of LIDs results in higher flood mitigation efficacy.

INTRODUCTION Humans and plants depend on an adequate supply of clean water for numerous reasons, from food production to sustaining terrestrial and aquatic life. The average Virginia resident uses about 47 gallons (178 L) of fresh water daily (VDEQ 2008). While a majority of Virginians are provided water from a centralized, public utility, there are nearly two million Virginia residents who depend on well water as their main source (VDH 2008). Replenishing groundwater withdrawals depends on recharge (water moving from the surface to groundwater) from infiltration of precipitation through permeable surfaces in the environment; an important part of the hydrologic, or water, cycle (VDEQ 2010). Forests and grasslands provide much of the available recharge area due to their high capacities to infiltrate precipitation. However, the urbanization process is rapidly converting forested areas and grasslands to commercial, residential, or industrial developments. This conversion creates a significant increase in impervious surfaces such as concrete, asphalt, building roofs, and even compacted vegetated sites (U.S. EPA 2003). Impervious surfaces decrease infiltration and groundwater recharge. They also generate increases in stormwater runoff; defined as any precipitation from a rain or snow event that flows off of an impervious surface. As water runs off urban impervious surfaces, it picks up sediment, oils, debris, nutrients, chemicals, and bacteria. The runoff is then collected in a conveyance system, transported, and discharged to surface waters such as creeks and rivers; most of the time without any type of water quality treatment (U.S. EPA 2003; Paul and Meyer 2001). In addition to carrying pollutants, the runoff is also typically warmer than the receiving surface waters. The increased volume and velocity of the stormwater runoff erodes soil and stream channels and can lead to stream “blow out.” Water quality is degraded and aquatic habitats are adversely altered (Meyer, et al. 2005, Booth and Jackson 1997). Due to the interconnected nature of watersheds, the degraded water travels downstream causing subsequent problems. The effect of increased development is an increase in stormwater runoff and associated pollutants into surface waters and a decrease in infiltration for groundwater recharge and stream base flows. Traditional practices for mitigating stormwater runoff impacts have targeted the management of peak runoff by using storage facilities such as detention and retention ponds. Mounting evidence that these methods are inadequate prompted the National Research Council in 2008 to advocate a shift to Low Impact Development (LID) practices to better meet stormwater quality and quantity management goals. LID is based on a set of techniques used in Prince Georges County, Maryland (Prince Georges County 1999). LID seeks to restore the natural hydrology of a site by minimizing the creation of impervious surfaces and increasing infiltration of runoff volume. The ineffectiveness of conventional management approaches and the implementation of the Chesapeake Bay and other critical watershed Total Maximum Daily Loads (TMDLs) caused Virginia to revise its entire process for regulating stormwater. LID and Environmental Site Design (ESD) practices are now used to design sites to meet hydrologic goals and to treat runoff to meet a net site nutrient export standard (Battiata et al. 2010). As of the date of this paper, 15 of these best management practices, or BMPs, have been approved for use by Virginia (Virginia Stormwater BMP Clearinghouse 2011). Similar approaches are being considered and adopted in other Chesapeake Bay jurisdictions, as well as nationally. The responsibility of stormwater management can be fragmented between state, local, and municipal government (Roy, et al. 2008), often differing from watershed to watershed. Because LID is decentralized, it changes the management focus from a large, regional scale to a site scale. Changes at the residential lot level can generate much greater infiltration over the watershed. Each homeowner can significantly reduce the stormwater load leaving their property, thereby improving surface water quality and helping to recharge groundwater reserves. From a green building perspective, LID techniques can provide a substantial credit under the LEEDS-ND (Leadership in Energy and Environmental Design-Neighborhood Development) program. The objective of this paper is to provide a relative context for runoff at the site scale, and an overview of the available BMPs that may be applicable.

Developing sustainable strategies by LID optimization in response to annual climate change impacts

Cities are more vulnerable to flooding due to the reducing of pervious areas influenced by urbanization and increases in extreme precipitation resulted from climate change. Conveying enlarging rainwater runoff requires an expansion of the draining system, which may cost a huge amount of grant investment. To deal with the problem, Low Impact Development (LID) techniques can be taken into consideration as a sustainable alternative option for urban drainage systems. However, the understanding of LID’s effects on urban flooding in different extreme rainfall characteristics is still limited. This study investigates potential performances of integration LID techniques (swale and infiltration trenches) in a drainage system by simulations EPA-SWMM models under different rainfall patterns for Quy Nhon, Vietnam. These performances have shown the effectiveness of the techniques in reducing the risks of flooding because of climate change. It also demonstrates that swales work more effectively in reducing flood probabilities which are caused by long duration and small peak rainfall compared to infiltration trenches. Whereas, infiltration trenches are more effective in reducing surface flooding but less efficient in cutting down the peak of generated runoff.

This study aims to investigate the effectiveness of the low impact development (LID) practices on sustainable urban flood storm water management. We applied three LID techniques, i.e. green roof, permeable pavements and bioretention cells, on a highly urbanized watershed in Istanbul, Turkey. The EPA-SWMM was used as a hydrologic-hydraulic model and the model calibration was performed by the well-known Parameter ESTimation (PEST) tool. The rainfall-runoff events occurred between 2012 and 2020. A sensitivity analysis on the parameter selection was applied to reduce the computational cost. The Nash-Sutcliffe efficiency coefficient (NSE) was used as the objective function and it was calculated as 0.809 in the model calibration. The simulations were conducted for six different return periods of a storm event, i.e. 2, 5, 10, 25, 50 and 100 years, in which the synthetic storm event hyetographs were produced by means of the alternating block method. The results revealed that the combination of green roof and permeable pavements have the major impact on both the peak flood reduction and runoff volume reduction compared to the single LIDs. The maximum runoff reduction percentage was obtained as 56.02% for a 10 years return period of a storm event in the combination scenario.

Stormwater runoff is a major concern in urban areas which is mostly the result of vast urbanization. To reduce urban stormwater runoff and improve water quality, low impact development (LID) is used in urban areas. Therefore, it is vital to find the optimal combination of LID controls to achieve maximum reduction in both stormwater runoff and pollutants with optimal cost. In this study, a simulation-optimization model was developed by linking the EPA Storm Water Management Model (SWMM) to the Multi-Objective Particle Swarm Optimization (MOPSO) using MATLAB. The coupled model could carry out multi-objective optimization (MOO) and find potential solutions to the optimization objectives using the SWMM simulation model outputs. The SWMM model was developed using data from the BUNUS catchment in Kuala Lumpur, Malaysia. The total suspended solids (TSS) and total nitrogen (TN) were selected as pollutants to be used in the simulation model. Vegetated swale and rain garden were selected as LID controls for the study area. The LID controls were assigned to the model using the catchment characteristics. The target objectives were to minimize peak stormwater runoff, TSS, and TN with the minimum number of LID controls applications. The LID combination scenarios were also tested in SWMM to identify the best LID types and combination to achieve maximum reduction in both peak runoff and pollutants. This study found that the peak runoff, TSS, and TN were reduced by 13%, 38%, and 24%, respectively. The optimal number of LID controls that could be used at the BUNUS catchment area was also found to be 25.

In recent years, plenty of simulation research about the low impact development(LID) control effect has emerged, but studies on scheme comparison and evaluation are lacking. In this study, a comprehensive benefit evaluation system for LID, including environmental, economic, and social benefits, was established on the basis of Analytic Hierarchy Process(AHP) and urban storm water model. Above all, benefit identification, quantitative evaluation and scheme comparison of single LID measures were obtained according to site investigation, simulated calculation and theoretical analysis. Whereafter, LID combination plans were designed based on single LID measures with high comprehensive benefit values, and their comprehensive benefits were evaluated to obtain the optimal plan. Then, based on well-founded system combined with Storm Water Management Model (SWMM), the design and optimization of LID were conducted, with a case in Xi’an, China. It turned out that the preferential order of the LID single measures according to the comprehensive benefit was: bio-retention > rain barrels > low-elevation greenbelt > green roofs > permeable pavement. Five LID combination plans were designed based on bio-retention, rain barrels, low-elevation greenbelt, and green roofs. Evaluation results showed that plan I (bio-retention and green roofs) was the optimal LID combination plan.

Green roof is a low impact development (LID) practice used to mitigate imperviousness in urban areas and to reduce flood risks. In order to have sufficient designs and accurate runoff predictions, computer models should be utilized with full understanding of green roofs' hydrologic processes. Evapotranspiration is usually considered important by researchers in the water balance modeling of a green roof. The Storm Water Management Model (SWMM) version 5.1 is widely utilized rainfall-runoff modeling software which has LID controls capable of modeling green roofs. A previous study has evaluated the performance of this model in green roof simulations for single events without considering evapotranspiration in its application, but attained negative outcomes. Thus, the objective of this study is to determine the significance of considering evapotranspiration in producing accurate runoff simulations specifically using SWMM 5.1. The results of this study have shown that when evapotranspiration was not considered, simulations failed to agree with observed values, whereas when evapotranspiration was considered, simulated runoff volumes attained a very good fit with the observed runoff volumes proving the significance of evapotranspiration as an important parameter in green roof modeling.

The Sustainable Drainage System module of the Town Energy Balance model (TEB-SUDS) was developed based on the Equivalent Sustainable Drainage System (E-SUDS) approach and has previously been applied to assess the hydrological responses of individual SUDS types. This study extends the analysis by evaluating the hydrological responses of aggregations of different compartments within an SUDS facility using the TEB-SUDS module. The presented results are benchmarked against the well- established Low Impact Development (LID) module of Storm Water Management Model (SWMM), demonstrating the high capability of the TEB-SUDS module in modelling the hydrological processes of SUDS facility for stormwater management.

This study aims to apply a cost-effectiveness approach to identify optimal Low Impact Development (LID) designs for peak flow management when two specific practices are simultaneously employed: Permeable Pavement (PP) and Green Roofs (GR). Four design parameters were considered, associated with coverage ratios and underlying layer thicknesses of the LIDs. The results showed that optimal costs and parameters were more affected by the level of peak flow reduction than by storms’ intensity and duration. The best settings occurred with permeable pavement treating 100% of the adjacent impervious area. In this case, the optimal designs were dominated by smaller coverage ratios (20 to 60%) and deeper (190 to 330 mm) storage layer of PP, combined with a very small or non-existent area of GR. The findings of the present study demonstrate how the optimization of design parameters may lead to more economic LID designs and provide additional guidance for LID practice implementation and to assist in the decision-making process for the most cost-effective and sustainable solutions.