Improving Urban Drainage Systems Resiliency Against Unexpected Blockages: A Probabilistic Approach

Considering the increase of flood hazards in many large cities, the rehabilitation of hydro-urban infrastructures is an important concern for the municipal authorities. A probabilistic approach based on Monte Carlo Simulation (MCS) is presented in this study to improve the resiliency of urban drainage systems when they are subject to unexpected structural blockages. The approach is integrated with SWMM simulation model and an evolutionary search algorithm to find the best set of rehabilitation measures under a significant number of blockage scenarios. Experimental results on the west zone of main drainage system in Tehran city indicate that proposed approach outperforms the conventional hydraulic-based methodology in terms of cost effectiveness and functionality. Results also show that adding the redundancy to the system by bypass lines in bottlenecks is considerably more efficient for flood mitigation and the increase of system resiliency under blockage incidents rather than using conventional methods such as detention ponds and enlargement of the channel sizes.     

城市河道生态修复方法初探

城市河道是城市社会经济发展必不可少的要素,是城市水系的载体,同时也是城市生态系统的重要组成部分.主要针对城市河道的治理,介绍了城市河道现状及国内外河道整治研究进展,详细阐述了城市河道生态修复的理论和内涵,并在此基础上介绍河道生态护坡、景观设计、水质修复等相关技术.     

国内外城市排水系统的回顾与展望

从国外城市排水系统各个发展阶段的特点及其最新进展出发，通过对比、分析找出国内外的差距，提出一些初步想法：适当的调整政策，并加大投资，以加快发展；引入城市排水管理的新观念，全面规划，提高效益；选择污水截流加处理作为改造现存直排式合流制的主要方案；积极创造条件，修订设计规范；建立我国的城市暴雨径流过程的计算机方法。     

城市小区管网排水及区域排涝水文计算方法初步探讨

城市小区管网排水和城市区域排涝两者概念不同，采用的标准和水文计算方法也有很大差别。从设计暴雨、产流、汇流等方面初步探讨了两种水文计算方法和成果的差异。     

Valuating the Receiving Waters of Urban Wastewater Systems through a Stakeholder-based Approach

The valuation of ecological services in European aquatic ecosystems is increasingly deemed to be an essential element for the integrated management concept pursued by the Water Framework Directive (2000/60/EC). However, the assessment methods are often doubted for their objectivity and transparency when based on the elicitation of stated preferences. The current research attempted to explicitly focus on the biases linked with the stakeholders participating in assessing methods operating with stated preferences. The most significant stakeholder groups were classified in three broad teams of Experts, Decision Makers and Affected Professions. The three teams' preferences were in turn assessed in economic and non-economic terms for the accentuation of the high fluctuation among the findings, and the threatening biases emerged in the sourcing of stated preference methods. The wastewater treatment plant in Athens, Greece and Saronikos Bay offered a sound case study.     

Many-Objective Optimization of Sustainable Drainage Systems in Urban Areas with Different Surface Slopes

Water Resources Management - Sustainable urban drainage systems are multi-functional nature-based solutions that can facilitate flood management in urban catchments while improving stormwater...     

Water Costs Allocation in Complex Systems Using a Cooperative Game Theory Approach

The management of complex water resource systems that address water service recovery costs and consider adequate contributions and priorities require methods that integrate technical, economic, environmental, social and legal aspects into a comprehensive framework. In Europe, the Water Framework Directive (WFD) 2000/60/EC recommends that the pricing politics in a river basin take into account the cost recovery and the economic sustainability of the water use. However, the current cost allocation methods do not consider the user’s willingness to pay and often do not permit a total cost recovery. Thus, a new approach is required that includes these requirements when defining water rates. This article presents a methodology to allocate water service costs in a water resource system among different users that attempts to fulfil the WFD requirements. The methodology is based on Cooperative Game Theory (CGT) techniques and on the definition of the related characteristic function using a mathematical optimisation approach. The CGT provides the instruments that are necessary to analyse situations that require a cost-sharing rule. The CGT approach can define efficient and fair solutions that provide the appropriate incentives among the parties involved. Therefore, the water system cost allocation has been valued as a game in which it is necessary to determine the right payoff for each player that is, in this case, a water user. To apply the CGT principles in a water resources system, the characteristic function needs to be defined and evaluated using an adequate modelling approach; in this study, it is evaluated using the optimisation model WARGI. (Sechi and Zuddas 2000). The so-called “core” represents the game-solution set. It represents the area of the admissible cost allocation values from which the boundaries on the cost values for each player can be supplied. Within the core lie all of the allocations that satisfy the principles of equity, fairness, justice, efficiency and that guarantee cost recovery. The core of a cooperative game can represent a useful instrument to define the water cost rates. Furthermore, it can be used as a valid support in water resource management to achieve the economic analysis required by the WFD. The methodology was applied to a multi-reservoir and multi-demand water system in Sardinia, Italy.     

An Integrated Framework to Evaluate Resilient-Sustainable Urban Drainage Management Plans Using a Combined-adaptive MCDM Technique

Due to the inevitability of urban flood in presence of the rainfalls exceeding design capacity of urban drainage system, resilience approach has been recently considered instead of the conventional urban drainage management. However, acceptance of resilience approach necessitates considering sustainability in the selection of urban drainage projects due to the various aspect of flood impacts. This paper presents a new integrated framework to show how urban drainage plans are resilient and sustainable. The framework consists of several indicators including technical, economic, social, environmental and planning aspects. On the other hand, the selection of suientropy of the probability distribution p _i . In fact, entropy reduces the effect of plan among available suggested plans is complicated in presence of multiplicity of the indicators. A new combined-adaptive multi criteria decision making technique including combination of Adaptive analytical hierarchical process, Entropy and TOPSIS is here introduced to facilitate the decision making process as well as dealing with uncertainties due to the subjective experts’ preferences. Moreover, presented framework are applied on a part of urban drainage system of Tehran, Capital City. Four urban drainage plans are designed and suggested to be evaluated along with existing system in terms of their sustainability and resilience. The results shows the presented framework provide comprehensive information regarding the behavior of the urban drainage plans against urban floods as well as their sustainability for urban managers. In addition, presented framework facilitates and accelerate the complicated process of decision making. Therefore, it can be employed as comprehensive decision support tool for resilient and sustainable urban drainage management.     

Multi-objective Evaluation of Urban Drainage Networks Using a 1D/2D Flood Inundation Model

The present paper describes a framework for the evaluation of a drainage system’s capacity in order to get a better understanding of the interactions between three rehabilitation measures: the Upgrading of Pipes (UP), Distributed Storage (DS) and the combination of both (UP+DS). It is posed as a multi-objective optimisation problem with the aim of minimising rehabilitation costs and flood damage. The approach of Expected Annual Damage Cost (EADC) was also introduced as the probabilistic cost caused by floods for a number of probable flood events (i.e. the accumulation of damage during a timeframe). The study combines computational tools such as a 1D/2D flood inundation model and an optimisation engine in the loop to compute potential damages for different rainfall events and to optimise combinations of rehabilitation measures. The advantages of this approach are demonstrated on a real-life case study in Dhaka City, Bangladesh. The optimal solutions confirm the usefulness and effectiveness of the proposed approach where both rehabilitation and damage costs are reduced by the optimal implementation of the UP and DS measures. In addition, the results of the proposed EADC approach indicate a damage cost reduction of at least 56% by implementing UP and of 27% by implementing DS, and both measures have lower rehabilitation costs. The proposed approach can be found appealing to water/wastewater utilities who are often challenged to achieve optimal design and rehabilitation of urban drainage systems.     

Investigation of Rainfall Forecast System Characteristics in Real-Time Optimal Operation of Urban Drainage Systems

This study investigates the role of rainfall forecast system characteristics in predictive real-time optimal operation (PRTOP) of urban drainage systems (UDSs). A simulation-optimization model is proposed integrating the stormwater management rainfall-runoff simulator, the harmony search optimization algorithm, and a rainfall forecasting module. This module generates different rainfall forecast scenarios depending on the forecast (time) horizon (FH) and the forecast type (perfect or imperfect). Five adaptive PRTOP models are compared to evaluate the relationships between the FH, forecast type, and the system’s relative regulating capacity (SRRC). The models are tested in a part of UDS of Tehran, capital of Iran. Results indicate that for the studied system, perfect knowledge of future rainfall is more beneficial for a specific range of the SRRC, equal to 80–90% of its upper bound. Besides, the performance of the PRTOP model improves with increasing the FH up to a certain point, and then having no further positive effect. Finally, the PRTOP model equipped with a hypothetical forecasting model where the forecast error is a nonlinear function of the forecast lead time still performs better than both a zero-FH reactive RTOP model and short forecast horizon PRTOP models.

     

Optimal Design of LIDs in Urban Stormwater Systems Using a Harmony-Search Decision Support System

During the last years, climate changes and urbanization are causing huge urban pluvial flood events in many countries in the world, driving to both develop and apply effective and innovative approaches for the design and management of urban stormwater systems. The gradual urbanization is provoking the increase of impervious surfaces and, consequently, of surface runoff and velocity and the reduction of concentration times of watersheds, both increasing soil erosion and worsening the water quality as a consequence of the intensive contamination. In this field, Low Impact Development (LID) practices for urban runoff control can be intended as an effective approach to both improve the urban resilience against the flooding risk and assure environmental interventions to adequate the urban stormwater systems to both climate and land use changes. In this paper, a Decision Support System (DSS) for the optimal design of LIDs in urban watershed is presented and discussed. The procedure is tested on Fuorigrotta (IT) and Ponticelli (IT) urban watersheds, with the aim of assessing the effectiveness of LIDs application in reducing both the flooded and conveyed volumes, at the expense of cost-effective solutions.     

Assessment of Penalty-Free Multi-Objective Evolutionary Optimization Approach for the Design and Rehabilitation of Water Distribution Systems

This paper describes a penalty-free multi-objective evolutionary optimization approach for the phased whole-life design and rehabilitation of water distribution systems. The optimization model considers the initial construction, rehabilitation and upgrading costs. Repairs and pipe failure costs are included. The model also takes into consideration the deterioration over time of both the structural integrity and hydraulic capacity of every pipe. The fitness of each solution is determined from the trade-off between its lifetime costs and its actual hydraulic properties. The hydraulic analysis approach used, known as pressure-dependent modelling, considers explicitly the pressure dependency of the water supply consumers receive. Results for two sample networks in the literature are included that show the algorithm is stable and finds optimal and near-optimal solutions reliably and efficiently. The results also suggest that the evolutionary sampling efficiency is very high. In other words, the number of solutions evolved and analysed on average before finding a near-optimal solution is small in comparison to the total number of feasible and infeasible solutions. We found better solutions than those reported previously in the literature for the two networks considered. For the Kadu network, for example, the new best solution costs Rs125,460,980—a significant improvement. Additional statistics that are based on extensive testing are included.     

A Dynamic Flow Forecast Model for Urban Drainage Using the Coupled Artificial Neural Network

Water Resources Management - Dynamic flow forecast, which is one of the critical technologies in the field of future Intelligent Drainage, has great potential for mitigating the damages resulting...     

屋面雨水系统研究的回顾

根据目前屋面雨水排水系统的工程实践和科技发展情况 ,结合过去的试验研究 ,阐述了雨水系统的泄水量与管内的流态变化情况。并对现行规范中的雨水斗 ,雨水立管的排水能力提出了修正建议     

A Distress-Based Condition Assessment Approach of Urban Water Assets Using Novel Deterioration Indices

Water Resources Management - This paper aims at proposing and demonstrating the application of a novel distress-based condition assessment approach to evaluate the physical condition of inspectable...     

Optimal Allocation of Flood Control Capacity for Multi-Reservoir Systems Using Multi-Objective Optimization Approach

Operation of multi-reservoir systems during flood periods is of great importance in the field of water resources management. This paper proposes a multi-objective optimization model with new formulation for optimal operation of multi-reservoir systems. In this model, the release rate and the flood control capacity of each reservoir is considered as decision variable and the resulting nonlinear non-convex multi-objective optimization problem is solved with ε-constraint method through the mixed integer linear programming (MILP). Objective functions of the model are minimizing the flood damage at downstream sites and the loss of hydropower generation. The developed model is used to determine optimal operating strategies for Karkheh multi-reservoir system in southwestern Iran. For this purpose, the model is executed in two scenarios based on “two-reservoir” and “six-reservoir” systems and for floods with return periods of 25 and 50 years. The results show that in two-reservoir system, flood damage is at least about 114 million dollars and cannot be mitigated any further no matter how hydropower generation is managed. But, in the case of developing all six reservoirs, optimal strategies of coordinated operation can mitigate and even fully prevent flood damage.     

王甫洲水利枢纽围堤排水沟坍塌的原因与修复

王甫洲水利枢纽围堤局部堤段下游排水沟产生渗透变形,对围堤的稳定构成威胁。通过分析排水沟变形坍塌的成因,提出在水库正常运行、不降低库水位的情况下,通过修改排水沟结构的设计,采用井点降水、铺垫压坡等施工技术,确保排水沟修复施工质量。获得了满意的修复效果。     

城市河流生态恢复系统分析

指出了目前城市河流面临的主要问题,以系统论的观点,基于生态系统尺度对城市河流进行生态系统恢复.从城市河流现状、生态恢复概念、恢复原则、主要内容、有待进一步解决的问题多方面对城市河流生态恢复进行了全面的论述.     

An Approach for Determination of the Drainage Network Effect on GIUH Using Hesitant Probabilistic Fuzzy Linguistic Sets

Water Resources Management - Digital elevation models (DEMs) enable extraction of stream networks, delineation of watersheds and determination of geomorphological characteristics. A widely used...     

A Scenario-Based Management of Water Resources and Supply Systems Using a Combined System Dynamics and Compromise Programming Approach

Water Resources Management - Long-term sustainability in water supply systems is a major challenge due to water resources depletion, climate change and population growth. This paper presents a...