Erfan Goharian

Low-Impact Development Practices to Mitigate Climate Change Effects on Urban Stormwater Runoff: Case Study of New York City

AbstractUrban stormwater runoff management systems are usually designed to meet performance standards based on historical climate data, which are assumed to be stationary. Based on the evidence from climate change impact studies, in the near future, stormwater management systems, within the built environment, may need to meet performance expectations under climatic conditions different from historical climate. Considering the impacts of climate change on rainfall intensities and stormwater runoff peak flow and volumes, and in turn the effectiveness of mitigation, practices for urban stormwater management are desirable. This paper presents the results of a climate change impact study on urban stormwater runoff in the Bronx River watershed, New York City. Considering the impacts of climate change on watershed runoff, the potential for low-impact development (LID) controls to mitigate the impacts was investigated. Stormwater runoff and LID controls were modeled using the U.S. EPA Storm Water Management Model...

Analysis of the Effects of Climate Change on Urban Storm Water Runoff Using Statistically Downscaled Precipitation Data and a Change Factor Approach

AbstractIn urban areas, there is concern that storm water runoff and flooding may be intensified because of the effect of climate change on precipitation amounts, intensities, and frequencies. Studies are needed to help storm water managers to plan and design effective adaptation and mitigation measures. This paper presents a study of the effects of climate change on urban storm water runoff in the Bronx River watershed in New York City. To show the effects of climate change on future precipitation, projections by 134 general circulation models (GCMs) from the fifth phase of the coupled model intercomparison project (CMIP5) are used. A new change factor method is proposed to select minimum, maximum, and mean daily precipitation scenarios for a future time period of 2030–2059. Because of the importance of short duration for extreme storm events, the daily precipitation is disaggregated to hourly increments. The U.S. Environmental Protection Agency storm water management model (SWMM) is used to model the hy...

Incorporating Potential Severity into Vulnerability Assessment of Water Supply Systems under Climate Change Conditions

AbstractIn response to climate change, vulnerability assessment of water resources systems is typically performed based on quantifying the severity of the failure. This paper introduces an approach to assess vulnerability that incorporates a set of new factors. The method is demonstrated with a case study of a reservoir system in Salt Lake City using an integrated modeling framework composed of a hydrologic model and a systems model driven by temperature and precipitation data for a 30-year historical (1981–2010) period. The climate of the selected future (2036–2065) simulation periods were represented by five combinations of warm or hot, wet or dry, and central tendency projections derived from the World Climate Research Programme’s (WCRP’s) Coupled Model Intercomparison Project Phase 5. The results of the analysis illustrate that basing vulnerability on severity alone may lead to an incorrect quantification of the system vulnerability. In this study, a typical vulnerability metric (severity) incorrectly...

Vulnerability Assessment to Support Integrated Water Resources Management of Metropolitan Water Supply Systems

AbstractThe combined actions of natural and human factors change the timing and availability of water resources and, correspondingly, water demand in metropolitan areas. This leads to an imbalance ...

Combined Impact of Inland and Coastal Floods: Mapping Knowledge Base for Development of Planning Strategies

AbstractConcurrent incidence of heavy rainfall events and coastal storm surges can cause damages of exponential proportion to the coastal habitants and infrastructures. Super Storm Sandy and hurricane Irene were wake up calls that the floodplains and evacuation zones in New York City need major revision. Federal and State emergency agencies have been working on revising the appropriate maps and spatial tools for planning and management purposes. This paper presents an integrated scheme for floodplain delineation in coastal areas, considering the combined effect of inland and coastal flooding. The proposed scheme is applied to the Bronx River watershed in the Bronx section of New York City. Consideration of inland and coastal flooding is provided by developing a conceptual rainfall-runoff model and a sea level simulation model. Climate change has intensified the intensity and frequency of extreme rainfall events and storm surges in the region. In order to evaluate climate change impacts on floodplain, proj...

Downscaling precipitation for local-scale hydrologic modeling applications: Comparison of traditional and combined change factor methodologies

AbstractFuture precipitation projections—and subsequent variation in simulated runoff response—can have a large impact on the planning and design of hydraulic structures and water systems and are, ...

LID Implementation to Mitigate Climate Change Impacts on Urban Runoff

Climate change can alter rainfall-runoff regime in urban areas by changing rainfall patterns and consequently increasing runoff peaks and volumes. Low Impact Developments (LIDs) and Green Infrastructure techniques are strategies which can be employed to control and decrease stormwater runoff in urban areas. In this study the potential for green infrastructure implementation to mitigate future climate change impacts on wet weather flow in the case study of the Bronx River watershed in New York City, USA, is analyzed. For this aim, the U.S. Environmental Protection Agency Storm Water Management Model (EPA SWMM) is created for the study watershed and driven by precipitation data from the IPCC CMIP5 which are temporally disaggregated using a new change factor methodology. In the following, the SWMM low-impact development (LID) controls component is used to investigate the effect of LIDs on runoff change. Flow-duration curves for historical and projected runoff by climate change are

Climate Change Impacts on Urban Runoff in a New York City watershed

Climate change is projected to have significant impacts on patterns of weather variables, all around the world. To study the impacts of climate change on rainfall, different global climate models (GCMs) and climate scenarios are used to build projections for probable future patterns of rainfall. Using the rainfall projections, the change in runoff peaks and volumes can be projected. In this paper,a climate change impact study is presentedto investigate the effect of future uncertain rainfall patterns on urbanrunoff in the Bronx River watershed in New York City,

Coastal Floodplain Mapping and Evaluation Using GIS and HEC-GeoRAS Models

Destructions caused by recent hurricanes on natural and built environment along New York City coastlines, emphasizeon the significance of delineating coastal floodplain and mapping the potential area of inundation followed by coastal floods. Floodplain delineation and appropriate planning in these areas, could help mitigating some of the flood damages. In this study,a Geographic information system (GIS) based method is proposed and appliedfor floodplain delineation in the coastal part of the Bronx River watershed, Bronx, New York City. Extreme water level in recurrence intervals of 2, 5, 10, 25, 50 and 100year is determined by frequency analysis of the extreme sea levels in the region provided by NOAA (National Oceanic and Atmospheric Administration).In order to determine coastal floodplain followed by increasing water level, HEC-RAS model is used. The GIS (geographic information system) capabilities are used for illustration of inundated regions. The results of the study show that the extent of floodplain perpendicular to the river direction, can be increased by up to 500 ft regarding the water level with 100year return period. Taking into account these results in determining land use of the floodplain besides the river, yields to mitigate the damages associated with coastal flooding caused by extreme water levels.

Using joint probability distribution of reliability and vulnerability to develop a water system performance index

AbstractAssessing the long-term reliability and vulnerability of municipal water supply systems often employs system modeling to analyze performance. Generally, decision-makers have long been in se...