The nexus of inhabitants and impervious surfaces at city scale — wastewater and stormwater travel time distributions and an approach to calibrate diurnal variations

ABSTRACT

We present an approach to calibrate dry weather flow patterns of people in eight subnetworks of Dresden, Germany. The monitored data was pre-processed, and SWMM model runs were performed. Congruence of modelled results and observed data was evaluated with the Nash-Sutcliffe Efficiency (NSE). New diurnal variation patterns of dry weather flow were quantified based on the presented calibration approach. Most of the modelled hydrographs exceeded an NSE of 0.9 just after the second SWMM model run, which is a sign of model adequacy. Travel time distributions (TTDs) of upstream wastewater from connected people and stormwater from impervious surfaces of the monitored locations were determined, and a dynamic index ?_iA-PE(k) was proposed, determined and its adequacy was assessed. In general, TTDs confirmed a lower population density and a less meshed urban drainage network in the outer parts of Dresden. The functional information within ?_iA-PE(k) considers development characteristics among the subnetworks and within a subnetwork of interest. The presented index is useful to evaluate prospective strategies of developments and the implementation of green and blue infrastructures in residential areas.     

Modelling low impact development in watersheds using the storm water management model

ABSTRACT

Low impact development (LID) has been widely used to manage stormwater, but evaluations of the benefits of implementing LID need to extend up to the watershed level. Modelling is an important method and this paper proposes an approach that focuses on modelling LID in watersheds using the Storm Water Management Model (SWMM). There are two ways to simulate LID in a SWMM. The first is using the LID editor, and the second is simply adjusting the parameters in the basic SWMM. In the proposed methodology, these two ways are combined. The methodology was applied to one of China’s pilot sponge -cities, Tsingtao. The results show that the method can improve the efficiency and guarantee the accuracy of the model at the watershed level. Use of LID application in the pilot area can significantly reduce runoff volume, but the effect is different in different sub-watersheds.     

Performance studies of R433A in a direct expansion solar-assisted heat pump

ABSTRACT

Energy assessment of a simple direct expansion solar-assisted heat pump system has been experimentally assessed with R433A as a possible alternative to R22. An artificial neural network integrated genetic algorithm model was developed to assess the performance system. The data obtained from the experimentation at different ambient conditions are used as the training data for the ANN network. The back propagation learning mechanism with variants Lavenberg-Maguardt with 20 neurons in the hidden layer were used in modelling of ANN. The values obtained from the analysis using ANN are optimised further by integrating the ANN procedure with GA. The results indicated that R433A has 6.4% and 1% lower instantaneous compressor power consumption and heating capacity compared to R22. Energy performance ratio of R433A was found to be about 5.67% higher compared to R22. The results confirmed that R433A can be used as a possible alternative to R22 DX-SAHP systems.     

Go Public!

Problem: While mortgage foreclosures are devastating communities across the United States, few planners know how to access the data necessary to document the number of foreclosures, where they are located, how the problem has changed over time, or how many households are affected, in order to assess how foreclosures affect borrowers, renters, and communities. There is no national dataset with foreclosure information, and in many communities, this information is buried in county property records, state legal files, and property auction lists.

Purpose: This article explains foreclosure as a process and describes how to use publicly available data to study foreclosure and inform outreach efforts. It shows how a collaborative effort among researchers and practitioners can produce useful data and analysis to reduce incidences of foreclosure. It concludes with suggestions for improving data access and quality.

Methods: The main foreclosure data used in the illustrative examples in this article were gathered from foreclosure court records and enhanced with data from property sales and tax records, Home Mortgage Disclosure Act data, and foreclosure sale records.

Results and conclusions: Although records on property foreclosures, real estate owned properties, and loan servicers are publicly available, accessing them, combining information from different records, and correcting mistakes to make them useful for analysis is time consuming and costly. Teams of researchers, public officials, and non-profits in a number of places, including one involving the author, have collaborated to build local foreclosure datasets using public data, producing accurate, property-level data that planners can use to guide policy, target direct outreach to at-risk borrowers and renters, and purchase distressed properties.

Takeaway for practice: Public entities hold some of the best data available on the foreclosure crisis but, in most places, accessing it involves considerable time, effort, and money. When researchers and practitioners work collaboratively to access and analyze these data their joint efforts can transform data-sharing practices and institutions, facilitating wider access and use in the future.

Research support: This research was supported by the Fund for New Jersey, NeighborWorks America, Local Initiatives Support Corporation (LISC), the Michael J. and Susan Angelides Public Policy Research Fund, the Edward J. Bloustein School of Planning and Public Policy at Rutgers University, Essex County, Hudson County/Jersey City, and Union County.     

A high resolution application of a stormwater management model (SWMM) using genetic parameter optimization

Low Impact Development (LID) tools and green infrastructure approaches have been developed and applied to mitigate the urbanization impacts on increasing runoff and pollutant washoff. The present work is the first part of a larger effort to simulate LID scenarios for a large scale urban catchment through up-scaling of high-resolution study catchments using the Stormwater Management Model (SWMM). In this study we present the setup, calibration, validation, and the results of a parameter sensitivity analysis of a high-resolution SWMM model for a highly urbanized small catchment located in Southern Finland. The homogenous subcatchments and associated narrow parameter boundaries, which are allowed by the high spatial resolution, result in insensitivity of SWMM to the fraction of impervious cover. The model optimization, using only the two identified key parameters “depression storage” and “Manning's roughness n for conduit flow”, yielded good performance statistics for both calibration and validation of the model.     

Visualising things. Perspectives on how to make things public through visualisation

In this paper, we will be discussing how visualisations can facilitate participatory processes by way of conveying issues of public concern as ‘things’. In the line of Latour’s plea to ‘make things public’, visualisations can be purposefully designed to trigger and encourage public debates concerning a wide range of issues. For this, we explore how a visualisation can be both transparent (i.e. visualising the complex entanglement of backstories of an issue) and readable. Specifically, we clarify the aspect of designing a readable visualisation of ‘things’. First, drawing from different fields of literature (i.e. Information Visualisation, Science and Technology Studies and Human-Computer-Interaction) we will articulate three main aspects of readability: engaging people to interact with a visualisation of complex issues, supporting sense making and encouraging reflection. Then, based on three empirical case studies, we indicate different design considerations in terms of engaging people to interact with a visualisation: contextualising a visualisation (via its location or medium), staging interaction and allowing people to provide their own perspective on the issue displayed. As a conclusion we propose a scenario that allows the visualisation to gradually become more transparent in support of its readability.     

Comparing Land Use Forecasting Methods: Expert Panel Versus Spatial Interaction Model

Problem: Legal requirements and good planning practice dictate that land development induced by major highway investments be forecasted. Two forecasting methods, the first qualitative and based on expert judgment and the second quantitative and based on formal spatial interaction models, are often presented as equivalent.

Purpose: We aim to extract lessons about the strengths and weaknesses of the two methods from a case study of a controversial highway, the Intercounty Connector (ICC), in the suburbs north of Washington, DC.

Methods: We compare forecasts of induced development obtained using both methods and judge their reasonableness against the empirical literature.

Results and conclusions: The two methods gave dramatically different results. The subjective judgment of experts predicted small impacts, on average, compared to a simple spatial interaction model. Also, subjectively forecasted impacts were limited to lands near the new facility, while modeled impacts rippled out across a much larger area. The subjective method seemed to give too little weight to accessibility effects and too much to zoning constraints, while a simple spatial interaction model seemed to do the opposite.

Takeaway for practice: Where time, budget, or data limitations preclude the development of state-of-the-art integrated land use and transportation models, we conclude based on this case study that the best approach is to combine simple models and expert judgment. Expert panels can be used to check model inputs against local knowledge and to adjust outputs in light of factors otherwise unaccounted for. Conversely, model outputs can be used to check expert opinion for inconsistency with known land use–transportation relationships.

Research support: None.     

Hotspots for Growth

Problem, research strategy, and findings: Our study contributes to the ongoing debate about the ability of Maryland's Priority Funding Area (PFA) program to control urban sprawl. We develop an economic-based land use conversion model to estimate if the PFA program steers urban growth to locations inside targeted growth areas within a fast-growing, exurban county. The results indicate that the size of an agricultural parcel, its distance from urban parcels, its proximity to highways, the productivity of agricultural land, and location in or outside PFAs influence the probability an agricultural parcel will be converted to urban use. We find that some of the parcels experiencing the greatest market pressure for development are located outside PFAs, and Maryland's incentive-based strategy is not completely effective at preventing sprawl.

Takeaway for practice: Careful design of the location of entrances and exits on and off highways, limitation of agricultural parcel fragmentation, and vigilant control of land use change in unproductive agricultural areas can limit sprawl. Our analysis highlights, yet again, the importance of communication between transportation and land use planners.

Research support: The research was supported by funding from the Harry R. Hughes Center for Agroecology, Inc.     

Development and application of an automated subcatchment generator for SWMM using open data

An open source subcatchment generator program was developed for the Stormwater Management Model (SWMM) to automate tedious stages in the model construction process. The generator divides the investigated area into subcatchments using a uniform computation grid and connects the grid cells together and to the underlying stormwater network. The system was tested by applying it to two small urban catchments with different fractions of impervious surfaces in Helsinki, Finland, using mostly openly available data. The simulated discharge results were compared to measured data and to results obtained from manually built models. The proposed system significantly accelerated the setup of a SWMM modelling project, as the routing between the subcatchments as well as the subcatchment slopes and flow widths were directly derived from the computation grid. Automatically generated and manually constructed SWMM models produced discharge results that differed only slightly from each other.     

Evaluating the SWMM LID Editor rain barrel option for the estimation of retention potential of rainwater harvesting systems

The low-impact development (LID) Editor rain barrel option of release 5.5 of the EPA storm water management model (SWMM) software does not allow the consideration of demand-driven behaviour of domestic rain water harvesting (RWH) systems to evaluate their runoff retention potential. This paper compares the results of the LID Editor with those obtained by a detailed demand-driven tank model scheme – used as a benchmark – and developed using basic functions of SWMM. The comparison showed the LID Editor-based model to generally overestimate the benchmark model in the evaluation of both volumetric and peak retention efficiency. The high variability of the results of the comparison suggests the use of the LID Editor rain barrel option for long-term simulation but not for single event analysis. A sensitivity analysis revealed that the overestimation provided by the rain barrel option is significant for tanks smaller than 2 m³, tank sizes of major diffusion for domestic RWH.     

基于3D Mine-ANSYS-FLAC~(3D)软件的三维地质数值建模方法

针对FLAC~(3D)建立复杂三维地质数值模型难度较大的问题,提出了一种快速有效的建模新方法。该方法首先利用3D Mine软件对Auto CAD平面图中的等高线和钻孔数据进行三维可视化操作,并输出为地层实体SAT文件或XY平面上等间距的三维坐标数据,利用自编程序将三维坐标数据转化为ANSYS可以识别的APDL语言文件后生成多个实体模型,经过ANSYS布尔操作、划分网格后利用接口程序导入FLAC~(3D),从而实现直观、快速地创建复杂地质体FLAC~(3D)模型。该方法在四川峨胜石灰石矿山三维地质数值建模中得到了实际应用,结果表明该方法是完全可行和有效的。     

微粒群多目标优化率定暴雨管理模型(SWMM)研究

针对SWMM存在模型参数多、率定困难的问题,采用微粒群算法(PSO0)对SWMM模型进行优化率定研究,完成了高维多目标优化率定过程.算例结果表明,微粒群算法可以有效地完成优化率定过程,并能实现多目标优化,这对模型率定和实际城市防汛工作具有一定指导意义.     

基于数据库建模的DWG文件数据挖掘模型研究

对设计院和设计部门积累的AutoCAD文件进行知识发现,具有非常重要的意义。而单纯的图形文件并不能有效的进行知识挖掘,因此如何将大量图纸中的信息提取出来是数据挖掘的基础和根本。给出一个基于数据库建模的体系结构模型,利用ActiveX Automation技术提取图形文件中包含的海量信息并存储到数据库中,将AutoCAD文件转换成为常用的数据库,在此基础上便可使用数据库的各种挖掘工具进行知识挖掘,从而为工程设计提供知识支持。     

基于GIS构建SWMM城市排水管网模型

基于地理信息系统(GIS)对SWMM城市排水管网模型进行快速构建,并在澳门某小区进行了应用和案例分析.结果表明,该方法简便快速,可准确提取排水管网的空间结构和属性数据,模拟结果与监测数据达到较好的拟合,为模型的进一步深入应用奠定了基础,对其他分布式水文模型的空间结构和属性数据的获取也有一定的借鉴意义.     

基于扩散波方法的管网排水过程数值模拟

基于扩散波方法,构建了一套排水管网水动力模型,并与已开发的高分辨率城市地表水文水动力模型进行了耦合。以理想排水管网和陕西省西咸新区沣西新城某小区实际排水管网的排涝过程验证模型,并模拟城市暴雨致涝过程。结果表明:理想算例中,该模型与SWMM模拟排水口流量过程高度吻合;实际算例中,与实测排水口流量过程对比,该模型的Nash-Sutcliffe效率系数分别为0.74、0.72、0.93和0.71,大于SWMM模型的0.62、0.66、0.73与0.65。在模拟研究区内涝积水过程时,计算数据与实测数据吻合度高,内涝积水点均实现精确模拟。     

Assessing methods for predicting green roof rainfall capture: A comparison between full-scale observations and four hydrologic models

To optimize the application of green roof technology, there is a need to quantify stormwater mitigation in advance of green roof construction. This study contributes toward meeting this need by assessing the utility of four hydrologic models for predicting green roof rainfall capture, including the: (1) curve number method, (2) characteristic runoff equation, (3) Hydrological Evaluation of Landfill Performance (HELP V3.9D) model, and (4) Storm Water Management Model (SWMM V5.1). Modeling results were compared to over twenty-four months of observed runoff data, collected between June 2011 and December 2013, from two full-scale green roofs in New York City (NYC). Both the curve number method and characteristic runoff equation had the highest Nash-Sutcliffe efficiency index (NSEI) between modeled and observed cumulative runoff depth per event (NSEI = 0.97) due to parameter calibration requirements, where error was mainly due to variations in green roof antecedent moisture conditions. The HELP model was originally intended for evaluation of a continuous landfill cover. As a result, HELP's inability to account for the non-vegetated areas on green roofs caused underestimation of runoff depth for most events (NSEI = 0.84). Alternatively, the SWMM model tended to overestimate event runoff depth (NSEI = 0.94), thought to be the result of its storage term parameterization. Model assessments point to the need for more robust parameter estimation methods, particularly for inputs that are statistical or difficult to measure directly, to improve pre-development accuracy of green roof performance models.     

Statehouse Versus Greenhouse

Problem: In the absence of U.S. federal action to address the problem of climate change, a diverse array of nonfederal policy entrepreneurs and climate action planners has produced an impressive body of plans and policies to fight climate change at the regional, state, and local levels. Their actions are highly laudable, but have they actually reduced greenhouse gas (GHG) emissions?

Purpose: This article evaluates the work of a group of innovative state-level policy entre-preneurs whose actions were chronicled by Barry Rabe, and a set of 29 state climate action plans systematically analyzed by Stephen Wheeler. It compares states with and without climate policy entrepreneurs and states with and without climate action plans, asks if either plans or entrepreneurs have been successful in reducing CO2 emissions, and identifies the elements within plans that are associated with the greatest reductions.

Methods: The analysis uses multiple regression models to explain changes in per capita CO2 emissions attributable to residen-tial, commercial, transportation, and total nonindustrial end users from 1990 to 2007. A package of control variables accounts for political, social, climatic, economic, and urban form factors, while policy variables isolate the effects of climate policy entrepre-neurs, climate action planners, and specific policy recommendations within climate action plans.

Results and conclusions: State-level climate actions reduce GHG emissions by a measurable but modest amount: about one half metric ton per person per year. This represents 2–3% of the average American's 24-ton annual total GHG emissions. The reduction is small in comparison to the magnitude of the problem, but a substantial tax increase or population shift away from sprawling areas would be necessary to achieve the same reduction. specific policies I find to be associated with lower emissions include: building efficiency in both residential and commercial sectors, Leadership in Energy and Environmental Design (LEED) policies in the commercial sector, and California's vehicle efficiency standards in the transportation sector.

Takeaway for practice: It is encouraging that we can already identify emission reduc-tions related to state climate action. However, the observed reductions remain small com-pared to the scope of the problem. These findings should persuade states without plans to begin the planning process while encourag-ing states with plans to encourage more entrepreneurship aimed at developing a second generation of policy options for stabilizing our planet's climate with or without federal action.

Research support: None.     

It’s Time to End Single-Family Zoning

Abstract

Local planning in the United States is unique in the amount of land it reserves for detached single-family homes. This privileging of single-family homes, normally called R1 zoning, exacerbates inequality and undermines efficiency. R1’s origins are unpleasant: Stained by explicitly classist and implicitly racist motivations, R1 today continues to promote exclusion. It makes it harder for people to access high-opportunity places, and in expensive regions it contributes to shortages of housing, thereby benefiting homeowners at the expense of renters and forcing many housing consumers to spend more on housing. Stacked against these drawbacks, moreover, are a series of only weak arguments in R1’s favor about preferences, aesthetics, and a single-family way of life. We demonstrate that these pro-R1 concerns are either specious, or can be addressed in ways less socially harmful than R1. Given the strong arguments against R1 and the weak arguments for it, we contend planners should work to abolish R1 single-family zoning.     

基于SWMM模拟上海市区排水及地面淹水过程

针对上海市城区排水系统的水文水力学特性，以SWMM（Storm Water Management Model）为基础开发出适合上海市区产流及排水特点和防汛管理要求的城市雨洪模型。模拟结果表明，该模型的计算结果较为理想、可靠，可在实时和规划条件下动态模拟各排水片和街区的地面积水全过程，并能满足市区防汛预报、水情分析、工程规划与管理等工作的要求。该模型对其他城市的类似工作具有较好的参考价值和指导意义。