Rainfall-Runoff Simulation Using Climate Change Based Precipitation Prediction in HEC-HMS Model for Irwin Creek, Charlotte, North Carolina

摘要

Flooding in major urban areas are due to the intense rainfall and insufficient capacity of storm sewers system to suitably route the peak flow within the watershed. With increase in imperviousness due to urbanization and increase in precipitation due to changing climatic condition, storm water management has become crucial and equally challenging. Suitable approach for prediction of peak flow based upon the available historical precipitation data, land use condition, soil type, and suitable routing method is necessary. This study focused on the use of Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) for the prediction of peak flow condition in Irwin Creek watershed (15.46 sq.km) located in Charlotte, North Carolina. The urbanized area is prone to flooding on intensified storm events as evidenced recently during the Hurricane Matthew. Using precipitation data from United States Geological Survey (USGS) rain gauge stations, hydrological model was developed in HEC-HMS. Using geospatial hydrologic modeling extension (HEC-Geo HMS) in Arc GIS, watershed for Irwin Creek with 13 sub-watersheds was created. Curve number grid for each sub watershed was prepared in Arc GIS from the land cover and soil group data. Basin model file prepared from HEC-Geo HMS containing all the required hydrological parameters was imported into HEC-HMS. USGS streamflow station data was used for the calibration and validation of the model. 6 hr. 100 yr. storm event produced by National Oceanic and Atmospheric Administration (NOAA) was routed through calibrated model to generate the peak flow of the watershed. Additionally, the impact of climate change on precipitation resulting the peak flow was assessed using climate data developed by North American Regional Climate Change Assessment Program (NARCCAP). Delta change factor of 1.18 was calculated for this study from Hadley Regional Model 3-Hadley Center Coupled Global Climate Model, a regional climate model- global climate model paired model used by NARCCAP. Through the critical analysis of the peak runoff generated by the calibrated model for NOAA rainfall data and NARCAAP rainfall data, 43% increase in peak flow was determined for 18% increase in storm depth. The study highlighted the significance of consideration of climate change factor that is likely to result in increased peak discharge in the existing urban watersheds. Hence, the results from this study suggested the necessity of suitable runoff-reduction approaches like low impact development for the further development of the study area.