Urban Flood Control Research Articles

기상레이더와 지형정보시스템을 이용한 분포형 강우-유출 유역모형의 개발과 검정

기상레이더와 지형정보 시스템을 이용한 홍수사상에 기초하고, 운동역학적이며, 초과강우가 고려된 분포형 강우-유출 유역모형이 개발되었다. 이 유역모형에서 강우로 인한 지표면 유출 및 지표면 흐름과 관련된 각종 변수의 공간적 변동성과 불확실성을 인식하고 설명한다. 개발된 모형은 래스터 지형정보시스템과 공간적ㆍ시간적으로 변하는 강우자료와 호환된다. 몬테칼로 모의와 우도값이 이 모형의 검정을 위하여 이용되었으며, 검정 모형으로부터 반응되는 시스템의 가능범위가 허용되었다. 레이더-강우 추정에 대한 보정으로 강우계가 이용되고, 복잡한 토지이용 상태인 미국 덴버시 도시배수홍수조절 구역내에 있는 두 개 유역들(Ralston Creek와 Goldsmith Gulch 유역)의 제한된 기왕 홍수사상에 이 모형이 적용되었다. 제한된 수의 몬테칼로 모의들과 고려된 홍수사상들을 근거로 관측수문곡선과 계산수문곡선을 비교하여, Nash와 Sutcliffe 효율점수의 범위를 얻게 되었으며, 그 범위는 Ralston Creek과 Goldsmith Gulch 유역에 대한 검정모형들로부터 각각 -0.19∼0.95와 -0.75∼0.81이다. 또 한, Ralston Creek과 Goldsmith Gulch 유역의 Nash와 Sutcliffe 효율점수는 유출용적에 대해 각각 0.88과 0.1, 첨두유량에 대해 0.14와 0.71, 첨두유량 도달시간에 대해 0.99와 0.95로 평가되었다. An event-based, kinematic, infiltration-excess, and distributed rainfall-runoff model using weather radar and Geographic Information System(GIS) was developed to acknowledge and account lot the spatial variability and uncertainty of several parameters relevant to storm surface runoff and surface flow The developed model is compatible with raster GIS and spatially and temporally varied rainfall data. To calibrate the model, Monte Carlo simulation and a likelihood measure are utilized; allowing for a range of possible system responses from the calibrated model. Using rain gauge adjusted radar-rainfall estimates, the developed model was applied and evaluated to a limited number of historical events for the Ralston Creek and Goldsmith Gulch basins within the Denver Urban Drainage and Flood Control District (UDFCD) that contain mixed land use classifications. While based on a limited number of Monte Carlo simulations and considered flood events, Nash and Sutcliffe efficiency score ranges of -0.19∼0.95 / -0.75∼0.81 were obtained from the calibrated models for the Ralston Creek and Goldsmith Gulch basins, based on a comparison of observed and simulated hydrographs. For the Ralston Creek and Goldsmith Gulch basins, Nash and Sutcliffe efficiency scores of 0.88/0.10, 0.14/0.71, and 0.99/0.95 for runoff volume, peak discharge, and time to peak, respectively, were obtained from the model.

Detention/retention storages for peak flow reduction in urban catchments: Effects of spatial deployment of storages

Stormwater management techniques for urban flood control have remained relatively unchanged in many practices throughout the world for most of the past 150 years. In the past 30 years, however, detention and/or retention techniques have been acknowledged as alternative approaches capable of meeting flood control objectives while providing environmental benefits and, sometimes, cost savings to developers and authorities responsible for stormwater management. In many places the use of detention and/or retention techniques has become common practice, particularly in urban catchments where open space for flood control is in short supply.This paper reports results of hydrological modelling undertaken in a hypothetical urban catchment using basic hydrographs generated by the DRAINS computer package.3 The two main aims of the modelling were 1) to explore the influence of position of retention and detention flood management elements on end-of-catchment catchment ‘peak flow’ outputs in hypothetical urban catchments, and 2) to provide clear, comparative information on the performances of the different strategies examined.The outcome from this study will not necessarily be applicable directly to all urban catchments, however it is possible that a refinement of generic flood control strategies could be developed as further related studies are undertaken in this area.

Urban Flood Control through a Mathematical Cell Model

This study models urban flood behavior by the flow cell scheme. The flow cell concept has origins in the Mekong River Delta Model (Zanobetti et al., 1970) and is historically used to simulate large rural floodplains. The flow cell concept was used to model the Pantanal Matogrossense, a large Brazilian marsh watershed of ecological importance (Mascarenhas and Miguez, 1993). That work is here adapted to model the diversity of drainage in the city of Joinville, Santa Catarina in southern Brazil.

Hydrologic Design of Urban Flood Control Detention Ponds

Three different approaches can be used for the hydrologic design of flood control detention ponds that service urban catchments: (1) design storm approach; (2) continuous simulation approach; and (3) analytical probabilistic approach. In this study, the three approaches were compared for the first time using a hypothetical catchment in Chicago, Illinois. While all three approaches can generate similar results, the results from the design storm approach were shown to vary by 40% to 50% depending on the choice of models and design storms. An appreciation of this level of variation of the results and the development of procedures for the reduction of this variation are recommended for better application of the design storm approach. The results presented in this paper further verify the suitability of the analytical probabilistic approach for the hydrologic design of urban flood control detention ponds.

Risk based urban watershed management under conflicting objectives

Ecological impairment and flooding caused by urbanization can be expressed numerically by calculating the risks throughout the watershed (floodplain) and along the main stems of the streams. The risks can be evaluated in terms of the present and/or future. This article describes the methodologies for ascertaining the risks in the Geographical Information Systems (GIS) environment. The objectives of urban flood controls and ecological preservation/restoration of urban waters are often conflicting and, in the past, the sole emphasis on flood control led to destruction of habitat and deterioration of water quality. An optimal solution to these two problems may be achieved by linking the risks to the concepts of risk communication, risk perception, and public willingness to pay for projects leading to ecological restoration and ecologically sustainable flood control. This method is appropriate because, in each case, public funds are used and the projects require approval and backing of policy makers and stakeholders. This article briefly describes a research project that attempts to resolve the conflict between the flood protection and stream ecological preservation and restoration and suggests alternative ways of expressing benefits of urban stream flood control and restoration projects.

Fort Collins Flood 1997: Comprehensive View of an Extreme Event

The July 1997 flood in Fort Collins was caused by the heaviest rains ever documented over an urbanized area in Colorado, and offers a data base and multifaceted set of lessons about flood planning, mitigation, response, and recovery for engineers, flood managers, and urban officials. The storm dropped 10 to 14 inches in 31 hours and some peak discharges greatly exceeded projected 100-year and 500-year flows. Five people died, 54 were injured, about 200 homes were lost, and 1,500 homes and businesses were damaged. Damages at Colorado State University were about $100,000,000, including catastrophic losses to the library. The paper summarizes the flood experience and provides lessons in five categories: urban drainage and flood control, risk management, mitigation, flood response, and public involvement.

Development of a state policy for sustainable urban drainage

A survey of state and municipal administrations’ performance on urban flood control and drainage is presented as a basis for discussing urban stormwater and sustainability. The investigation was done as part of a strategy for the development and implantation of a sanitation policy in the state of Santa Catarina, in southern Brazil.

Multiobjective Watershed-Level Planning of Storm Water Detention Systems

Detention basins are the most popular structural measure for urban flood control and have proven effective for both water quantity and quality management. Integrated, watershed-level planning of the layout and sizing of detention systems is essential because localized solutions may actually aggravate the negative impacts of urban drainage. Successive reaching dynamic programming (SRDP) is applied to minimize detention system costs of maintaining ranges of desired downstream peak flow attenuation, with basin and channel routing imbedded within the algorithm. A multiobjective genetic algorithm (MOGA) is also applied to generating nondominated solutions for system cost and detention effect for a watershed-level detention system. These algorithms are applied to a layout and design of a stormwater detention system in the Pazam watershed located in southern Taiwan. The case study confirms the robustness and computational efficiency of the SRDP algorithm, and the MOGA generates a wide range of nondominated solutions for trade-off analysis using a proposed \Ielite solutions conservation\N procedure.

Towards a universal stormwater management practice for arid zone residential developments

The principal centres of research and development in stormwater management are in the World's temperate regions for which a wide range of best practices are already known. The article suggests a strategy for improving performance in urban flood control, pollution minimisation and stormwater harvesting in arid/semi-arid regions. The basis of the approach is, firstly, systematic documentation of performances in strategic project cases – by regions – followed by integration of these into a universal best practice. A documentation matrix for stormwater management cases in Adelaide, South Australia, is described. Factors considered in the matrix include devices and treatments, development types and forms, aquifer recharge capability and soil types. The matrix will provide, progressively, vital information for planners and designers and guide researchers in the most productive use of limited monitoring resources.

Towards a universal stormwater management practice for arid zone residential developments

The principal centres of research and development in stormwater management are in the World's temperate regions for which a wide range of best practices are already known. The article suggests a strategy for improving performance in urban flood control, pollution minimisation and stormwater harvesting in and/semi-arid regions. The basis of the approach is, firstly, systematic documentation of performances in strategic project cases — by regions — followed by integration of these into a universal best practice. A documentation matrix for stormwater management cases in Adelaide, South Australia, is described. Factors considered in the matrix include devices and treatments, development types and forms. aquifer recharge capability and soil types. The matrix will provide, progressively, vital information for planners and designers and guide researchers in the most productive use of limited monitoring resources.

Study on Integrating Uban Development and Restoration of Hydrologic Cycle by Systematizing its Components

The Housing and Urban Development Corporation (HUDC) for which the author had worked for about 30 years has implemented urban development projects totaling 32, 000ha as of today since its establishment in 1955, constantly playing a major social role in the development of new towns. This urban development has two aspects, i.e., supplying land for housing and development of urban infrastructures; both in combination have greatly contributed to creating well-planned new urban areas.This paper discusses the synthesizing process and integration of a comprehensive “hydrologic cycle restoration system” as an advanced form of various flood-controlling measures introduced by the HUDC, from a viewpoint of urban infrastructure development in realizing an ideal form of urban development and flood control.

Hydrology day

Registration for the Hydrology Day sponsored by the Front Range Branch of AGU on April 23 at Colorado State University in Fort Collins, Colorado, totaled 121 participants, of whom 61 were students.Thirty‐one individuals joined the Front Range Branch. Three students from Colorado State University won the awards for best paper in their category: Thomas W. Anzia (Sr.), ‘A Comprehensive Table of Standard Deviates for Confidence Limits on Extreme Events;’ Victor Nazareth (M.S.), ‘Aquifer Properties from Single‐Hole Aquifer Tests;’ and Roy W. Koch (Ph.D.), ‘A Physically Based Derivation of the Distribution of Excess Precipitation.’ Judges for the awards were Dr. Bittinger, Resource Consultants, Fort Collins; George Leavesley and Daniel Bauer, USGS, Water Resources Division, Denver; Scott Tucker, Executive Director, Denver Urban Drainage and Flood Control District; Charles Brendecke, Department of Civil Engineering, Univ. of Colorado, Boulder.

DEMAND SIGNALS FOR URBAN DRAINAGE AND FLOOD CONTROL PROJECTS1

ABSTRACT: Planning for urban drainage and flood control requires the use of a rational procedure for setting priorities and allocating funds. An innovative procedure developed by the Los Angeles County Flood Control District is described. It consists of the use of bond election voting results as a surrogate for demand signals representing the public preference for project approval. A regression equation has been developed to relate project characteristics to the likelihood of approval. The procedure is implemented through a “funnel‐screen” review procedure which results in a list of reviewed and approved projects.

Diel Periodicity of Chironomid 1 Larval and Pupal Drift in an Urban Flood Control Channel System

The diel drift periodicity of chironomid larvae and pupae in a flood control channel system was investigated on 4 occasions. A 15-min drift sample was collected every h over a period of 24 h by using a 130-μm pore plankton net. Hourly changes in current velocity and water temperature, and time of sunset and sunrise were recorded during each diel period. Larvae and pupae of Cricotopus bicinctus (Meigen), C. sylvestris (F.), Chironomus decorus Johannsen, and pupae of Paralauterborniella subcincta (Townes) drifted in higher numbers in darkness than in the daylight periods, with maximum numbers occurring within 5 h after sunset. Larvae of P. subcincta drifted more during the daytime. Water temperature and current velocity seem to have very little effect on numerical increases or decreases of these midge species in drift, except for larvae of P. subcincta . Darkness is considered to be the major entraining factor for the higher numbers of larvae and pupae of C. bicinctus , C. sylvestris , C. decorus , and pupae of P. subcincta occuring in drift during a diet period.

Integrating ecological and social considerations into urban flood control programs

A well‐planned flood control program requires integration of diverse sets of information to develop alternative remedial measures for public discussion and selection. Although procedures for the required hydrologic studies, engineering designs, and economic analyses are readily available, procedures for assessing effects on the natural environment and on social aspects are still being developed. This paper illustrates one approach to integrating all this information in comparing alternatives, using the Proctor Creek watershed in Atlanta, Georgia, as an example. The illustration begins with a program such as might be formulated by available planning methodology from hydrologic, economic, and engineering data. The illustration continues with suggestions on how to collect meaningful social suitability data from a questionnaire designed to document public perceptions and preferences, ecological data from natural areas in the floodplain, and data relating the effects of the floodplain land use to the well‐being of the community. A procedure for integrating these considerations with the established analyses into alternatives presented for public discussion and decision making is then illustrated. Suggestions are also made on how the selected flood control program can be most successfully implemented.

Seasonal Changes in Chironomid Fauna and Rainfall Reducing Chironomids in Urban Flood Control Channels 1

Seasonal population changes in chironomid fauna of an urban concrete-lined flood control channel system were studied from Aug., 1974–Sept., 1976. Benthic samples from 9 stations along a 20-km stretch of the channel system were collected biweekly and air and water temperatures and rainfall were also recorded. Midge larvae of 7 genera were taken. Cricotopus spp., Dicrotendipes sp., and Chironomus spp., in that order, were of quantitative importance; the other 4 genera collectively formed 0–7% of the total monthly-collected larvae. Cricotopus spp. were present year-round, forming >86% of the total midges collected and 65–99% of the monthly totals. Dicrotendipes sp. (densest May–Nov.) were also present throughout the year, but their monthly populations ranged from <1–34% of the total. Chironomus spp. occurred from July–Nov., their density reaching up to 28% of the total midges taken then. The numerical increase in midges during the spring and summer coincided with warmer air and water during these periods. Two to 3 cm or more of rainfall in the area in a 24-h period drastically reduced larval populations, but within 2–4 wk, after a period of rainfall, they greatly increased.

Substrate Type as a Factor Influencing Spatial Distribution of Chironomid Midges in an Urban Flood Control Channel System 1

Spatial distribution of chironomid midges in relation to the various substrate types in a concrete-lined flood control channel system carrying domestic and industrial waste water was studied. Bare concrete surfaces, filamentous algae, detritus, fine sand, and coarse sand and gravel were the 5 types of substrates in this drainage system. A minimum of 10 benthic samples from each of the 5 substrates prevailing in different sections of the channel system were collected, using a modified Surber sampler (0.09 m2frame and 500μpore net). The study was repeated on 4 different occasions. Midges belonging to 5 genera were taken. Chironomus spp. and Cricotopus spp. were the 2 most abundant groups forming 97.4% of the total midges taken on any occasion. Chironomus spp. larvae predominated in fine sand, whereas Cricotopus spp. larvae were associated with detritus. On all 4 sampling dates, fine sand contained 42–80% of the total Chironomus spp. larvae taken from all 5 substrates. Similarly, substrate composed of detritus supported 58–78% of the total Cricotopus spp. larvae. Midge larval densities in some parts of the channels exceeded 3000/0.09 m2on some occasions. During sampling, a number of drift-borne Chironomus spp. and Cricotopus spp. larvae and pupae contributed to the benthic collections.

Optimal Sizing of Urban Flood-Control Systems

Optimal sizes for components of urban flood-control systems can be determined from a detailed simulation analysis controlled by an optimization methodology. Flood-control measures within urban areas frequently consist of complex systems of detention storage reservoirs, channel modifications, levees, land-use controls, flood proofing, and pumping facilities. The optimal size of each of these system components depends on the system interaction with other components and the hydrologic, economic, environmental, and other performance outputs of the system. A technique has been developed and programmed for an existing simulation model that automatically determines the sizes of urban flood-control components of detention storage, flow diversions, and pumping plants that results in maximizing system net benefits subject to accomplishment of hydrologic performance targets. The system is simulated using hydrologic data, component cost and performance functions, and flow damage information at damage centers.

Evaluation and Implementation of Urban Drainage Projects

Urban drainage and flood control must compete for funding from the limited public purse. Other types of evaluation problems are: (1) The determination of the merit of individual projects; (2) the ranking of competing UDFC projects to determine priorities; (3) the determination of optimal investment timing; and (4) the determination of the incidence of costs and benefits on different population sectors so that project costs can be equitably apportioned. The UDFC systems may be distinguished into minor or major systems, both for implementation purposes and for evaluation studies and public benefits differ considerably between the two types of systems. In the case of the major flood control project, attention has been focused on the potential reduction in flood damages associated with such projects. All public programs, e.g., public safety, water supply library services, urban drainage and flood control, and others should be subjected to the type of analysis presented to identify precisely the benefits from expenditures of public funds and the recipients of the benefits.

Master Planning Methodology for Urban Drainage

Effective operation and maintenance of the urban environment requires the coordinated management of the various elements that comprise the urban area. One of the principal elements of the urban system is that of water resource management which includes urban drainage and flood control. A systems engineering methodology was developed for master planning of the major drainage system in the Denver area under Project REUSE (Renewing the Environment through Urban Systems Engineering). The methodology incorporates a functional description of the urban drainage system, and a systematic process of data acquisition, runoff analysis, concept identification and selection, and master plan development and implementation.