Predictive Assessment of the Performance of the Huancayo Rainwater System (Junín) in the Face of Climate Change: An Approach Using Digital Hydraulic Models

Urbanization is known to increase the volume of stormwater runoff and peak flow rates, which leads to changes in the natural flow regime and increases the likelihood of flooding. Low-impact development (LID) practices seek to reduce runoff volume and peak flow and are generally considered to be a more sustainable solution for urban stormwater management. In this study, we present a systematic approach to address nuisance flooding issues in small cities and communities. As an application, the effectiveness of two LID practices, rain barrels and permeable pavements, were explored in mitigating the urban flooding problem of a highly urbanized small coastal watershed in Alabama, USA. The EPA Stormwater Management Model (SWMM) was first calibrated for water depth using data collected at multiple sites within the watershed during the 2014–2015 period. The calibrated model was then used to first identify the areas prone to flooding using design storms with 1, 2, 5-, 10-, 50-, and 100-year return periods. Floodplain maps were generated for those design storms with HEC-RAS. Next, LID options upstream of those flood-prone areas were assessed to potentially minimize the flooding risks. The results indicate that LID controls can have considerable benefits for stormwater management by reducing runoff volume (1–24%), peak flow rates (18–25%), and water depth (5–15%), potentially returning watersheds to their natural flow regimes, thereby minimizing the flooding risk in urbanized areas. However, the effectiveness of LIDs, especially for the runoff volume, quickly diminishes as the return periods of the storms increase. Rain barrels were identified as the most economical and effective LID within the drainage system.

Low Impact Development (LID) is a green infrastructure approach to ease the surface runoff that arises due to climate change and from an increasing impervious surface area caused by urbanization. This study aims to determine which LID control is best suited for Barangay San Rafael, San Jose Del Monte, Bulacan. Using Storm Water Management Model (SWMM), a hydraulic model of the area was created to apply the LIDs and simulate a runoff. The data used in SWMM for the runoff simulation is the monthly rainfall values for year 2020. Based on the simulation using SWMM, the existing drainage system has a high total flood volume with total flood volume of 243.511 liters. Based on the data collected from SWMM, the most effective combination with total flood volume of 50.884 liters was the combination of all the LID practices. The study has used three (3) different LID practices and the combinations of the LID practices to obtain the ideal LID combination namely, Bioretention Cell, Bioswale, Bioswale and Permeable Pavement. In the final analysis, the combination of Permeable Pavement, Bioretention Cell, and Bioswale is the best combination out of the three LID controls mentioned. Bioretention Cells are primarily used in parking lot islands, traffic islands, and driveway runoff. The same is true for Permeable Pavement, which is used mainly on roadways and parking lot islands. Considering the total flood volume that the SWMM calculated, the combination of the three LID parameters alone has the lowest total flood volume.

Flood modelling is an effective way to manage the stormwater network in cities. It aims to understand and predict the behaviour of stormwater network so that it can test and evaluate effective solutions to structural and operational problems. So simulation modelling stays a preoccupation for building a successful hydraulic modelling in urban areas. This study investigates the impact of the design rainfall on the hydraulic modelling results for the Azzaba stormwater network located in the North-East of Algeria by using the Storm Water Management Model (SWMM). Four scenarios of design rainfall events were compared for 10, 25 and 50-year return periods, where we used double triangle and composite curves for the design rainfall event definition. The results show the impact of the choice of design rainfall on the behaviour of the stormwater network, from which the results of simulation by the double triangle method for the short durations represents a great risk on the probability that the stromwater network can overflow and flood the city, with a difference in peak discharge estimated at 62.97% and 58.94% for 2 h and 3 h events compared to the peak discharge simulated by the composite rainfall method.

Applying the Low-Impact Development (LID) approach in urban drainage systems can help control surface runoff, therefore mitigating the potential of flooding risk. However, its effectiveness varies widely, and various technical factors influence its performance. This study aims to determine the effectiveness and performance of LID units, namely bioretention and infiltration wells, in controlling surface runoff. The Center Park Housing area, covering an area of ​​11.53 hectares located in Palembang City, was chosen as the study area. The ability of the LID unit to reduce the volume and discharge of runoff, as well as the runoff coefficient, was simulated using the Storm Water Management Model (SWMM) program based on input from various design rainfall cases. There were four simulated design rainfalls, i.e. 108.76 mm (2-year return period), 133.20 mm (5-year), 149.38 mm (10-year), and 169.82 mm (25-year). The LID unit implementation scenarios were varied with the number of infiltration well units of 1 - 4 units per house plot. The number and area of ​​bioretention units were considered constant for all scenarios. The simulation results show that the LID implementation can reduce runoff volume and peak discharge and help decrease the runoff coefficient in the study area effectively, especially in the case of lower design rainfall (2-year). The performance of the infiltration wells unit in producing runoff losses is better than the bioretention unit because its construction structure has a larger storage capacity for a similar unit area. Although the LID method is quite effective in reducing runoff, its combination with conventional methods may produce better performance, so further research that discusses this needs to be addressed.

Rapid urbanisation has caused an increased in peak discharge that conventional drainage systems cannot adequately handle. Low Impact Development (LID) practices are becoming a new approach in helping to better mimic the pre-development discharges. This study aims to evaluate the effectiveness of LID and Best Management Practices (BMP) under different rainfall conditions. Vegetative swale and detention pond were selected to represent LID and BMP. Simulations of four main scenarios namely, base case, LID, BMP, and combined LID-BMP were performed using Stormwater Management Model (SWMM). Results show that among the scenarios simulated, the combined LID-BMP is most effective with average peak flow reduction of 54%. This is followed by BMP that achieved 37% in average peak flow reduction as compared to 27% peak flow reduction by LID. The findings indicate the need for integrated strategy when dealing with stormwater management measures.

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

One of the main causes of urban inundation is the rise of impermeable surfaces brought on by increasing urbanization. Low impact development (LID) practices have been employed in previous studies to mitigate urban flooding. However, the effectiveness of LID practices in reducing runoff peaks and improving water quality is unknown, especially in the equatorial region. This study explored nine alternative scenarios to evaluate the effectiveness of the bioretention system and vegetated swale using the Storm Water Management Model (SWMM). Using precipitation data of December 2021, the Swinburne University of Technology Sarawak Campus has been chosen as the case study. The findings demonstrated that these two LID practices could significantly lessen urban flooding. Under scenario 7, the combination of 28.4% bioretention system and 11.3% vegetated swale reduced the maximum runoff peaks by 22.98% at Peak A, 24.71% at Peak B, and 24.09% at Peak C. In the meantime, under scenario 7, the implemented LID practice has removed 20.09% of TSS, 19.75% of TP, and 12.26% of TN. It was discovered that runoff peak reduction increases as the area covered by vegetated swale and bioretention system increases. The outcomes showed that bioretention system performed better than the vegetated swale in reducing peak runoff and enhancing water quality. Local authorities can use the findings of this study to offer recommendations for reducing disaster risk, controlling urban flooding, and revitalizing urban areas.

The present work aims at quantifying the benefit of Low Impact Development (LID) practices in reducing peak runoff and runoff volume, and at comparing LID practices to conventional stormwater solutions. The hydrologic-hydraulic model used was the Storm Water Management Model (SWMM5.1). The LID practices modeled were: (i) Green roofs; and (ii) Permeable pavements. Each LID was tested independently and compared to two different conventional practices, i.e., sewer enlargement and detention pond design. Results showed that for small storm events LID practices are comparable to conventional measures, in reducing flooding. Overall, smaller storms should be included in the design process.

Costs of Meeting Water Quality Goals under Climate Change in Urbanizing Watersheds: The Case of Difficult Run, Virginia

Rapid urbanization has increased impervious areas, leading to a higher flood hazard across cities worldwide. Low Impact Development (LID) practices have shown efficacy in reducing urban runoff; nevertheless, choosing the best combinations in terms of implementation cost and performance is of great importance. The present study introduces a framework based on green infrastructure, multi-objective optimization, and decision support tools to determine the most cost-effective LID solutions. The Storm Water Management Model (SWMM) was employed for rainfall-runoff and hydraulic modeling in Region 1, District 11 of Tehran, Iran. Six scenarios of different combinations of LID practices were developed. The system for Urban Stormwater Treatment and Analysis Integration (SUSTAIN) was used to optimize and evaluate each scenario. The selected solutions were imported to the SWMM to evaluate the stormwater system performance. Then, two multi criteria decision making (MCDM) models, including TOPSIS and COPRAS, were employed to rank the scenarios based on four technical and economic criteria. Results showed that scenario 4, consisting of rain barrels, porous pavements, and vegetated swales, had the best performance under TOPSIS with a 7.68 million USD and reduced the runoff volume and peak flow by 20.77% and 19.2%, respectively. However, Under the COPRAS method, Scenario 2 with a combination of rain barrels, bio-retention cells, and vegetated swales showed higher performance than the other scenarios with 3.25 million USD and led to a 15% reduction in the runoff volume and 4.30% in the peak flow. The COPRAS method was more sensitive to cost weights and chose the most economical scenario as the ideal. However, Scenario 4 concluded to be more feasible due to spatial limitations in the study area. The proposed SWMM—SUSTAIN—MCDM framework could be helpful to decision-makers in the design, performance evaluation, cost estimation, and selection of optimal scenarios.

A novel spatial optimization approach for the cost-effectiveness improvement of LID practices based on SWMM-FTC

This study integrates and develops methods, namely low impact development (LID) selection method and an LID spatial planning model, to enable decision-making to minimize pluvial flooding for a community. The objective is to minimize the flood risk under the worst case of the design storm within the budget constraints. Design storms in current and future climate scenarios are analyzed as input to the Storm Water Management Model (SWMM). Then, LID practices are selected based on the proposed procedure and a spatial planning model is built to identify the optimal LID layouts using the simulated annealing (SA) algorithm. The lower and upper bounds of the generated rainfall intensities of a five-year 1-h duration design storms for the Hadley Centre Global Environment Model version 2 for the atmosphere and oceans (HadGEM2-AO), the Norwegian Earth System Model (NorESM1-ME), and the CSIRO-Mk3.6.0 Atmosphere-Ocean GCM (CSIRO-Mk3.6.0) during 2021–2040 are derived. The LID selection helps efficiently identify appropriate LID. Results show that nearly no flood occurs under the optimal LID layouts found by the LID spatial planning model. Moreover, it is more optimal to invest in LID in the lower sub-catchments in LID planning when the budget is limited. These methods are generally applicable for a community using LIDs as adaptation measures against pluvial flooding.

Low impact development practices mitigate urban flooding and non-point pollution under climate change

Stormwater infrastructure designers and operators rely heavily on the United States Environmental Protection Agency's Storm Water Management Model (SWMM) to simulate stormwater and wastewater infrastructure performance. Since its inception in the late 1970s, improvements and extensions have been tested and evaluated rigorously to verify the accuracy of the model. As a continuation of this progress, the main objective of this study was to quantify how accurately SWMM simulates the hydrologic activity of low impact development (LID) storm control measures. Model performance was evaluated by quantitatively comparing empirical data to model results using a multievent, multiobjective calibration method. The calibration methodology utilized the PEST software, a Parameter ESTimation tool, to determine unmeasured hydrologic parameters for SWMM's LID modules. The calibrated LID modules' Nash-Sutcliffe efficiencies averaged 0.81; average percent bias (PBIAS) -9%; average ratio of root mean square error to standard deviation of measured values 0.485; average index of agreement 0.94; and the average volume error, simulated vs. observed, was +9%. SWMM accurately predicted the timing of peak flows, but usually underestimated their magnitudes by 10%. The average volume reduction, measured outflow volume divided by inflow volume, was 48%. We had more difficulty in calibrating one study, an infiltration trench, which identified a significant limitation of the current version of the SWMM LID module; it cannot simulate lateral exfiltration of water out of the storage layers of a LID storm control measure. This limitation is especially severe for a deep LIDs, such as infiltration trenches. Nevertheless, SWMM satisfactorily simulated the hydrologic performance of eight of the nine LID practices.

Urbanization necessitates Low Impact Development (LID) practices for sustainable development, but existing studies lack analysis about the comprehensive effect and optimal allocation of LID combination practices. To address this gap, this study conducted an in-depth analysis of the runoff control effects of individual and combined LID practices and pollutants under varying retrofit proportions, utilizing the Storm Water Management Model (SWMM). Four evaluation metrics were employed for parameter calibration and validation assessment to ensure the accuracy of the SWMM. The Response Surface Methodology (RSM) was then employed to optimize the retrofit proportions of LID practices due to its high efficiency and statistical rigor. The results showed that, under the same retrofit ratio, bio-retention (BC) has a better runoff reduction rate and pollutant removal rate. For example, when the retrofit proportion is 100%, the runoff pollutant removal rates of BC in Parcel 1 and Parcel 2 are 29.6% and 32.9%, respectively. To achieve a 70% runoff control rate, the optimal retrofit proportions for Parcel 1 were 67.5% for green roofs (GR), 92.2% for permeable pavements (PP), 88.9% for bio-retention cells (BC), and 50% for low-elevation greenbelts (LEG); these correspond to the proportions for Parcel 2 that were 65.1%, 68.1%, 82.0%, and 50%, respectively. In conclusion, this study provides scientific and technical support for urban planners and policymakers in urban rainwater management, especially in similar regions.