The intensification of the hydrological cycle due to climate change entails more frequent and intense rainfall. As a result, urban water systems will be disproportionately affected by the climate change, especially in such urban areas as Las Vegas, which concentrates its population, infrastructure, and economic activity. Proper design and management of stormwater facilities are needed to attenuate the severe effects of extreme rainfall events. The North American Regional Climate Change Assessment Program is developing multiple high-resolution projected-climate data from different combinations of regional climate models and global climate models. The objective of this study was to evaluate existing stormwater facilities of a watershed within the Las Vegas Valley in southern Nevada by using a robust design method for the projected climate. The projected climate change was incorporated into the model at the 100 year return period with 6 h duration depths, using a statistical regionalization analysis method. Projection from different sets of climate model combinations varied substantially. Gridded reanalysis data were used to assess the performance of the climate models. An existing Hydrologic Engineering Center’s Hydrological Modeling System (HEC-HMS) model was implemented using the projected change in standard design storm. Hydrological simulation using HEC-HMS showed exceedances of existing stormwater facilities that were designed under the assumption of stationarity design depth. Recognizing climate change and taking an immediate approach in assessing the city’s vulnerability by using proper strategic planning would benefit the urban sector and improve the quality of life.

Hydrological extremes associated with climate change are becoming an increasing concern all over the world. Frequent flooding, one of the extremes, needs to be analyzed while considering climate change to mitigate flood risk. This study forecast streamflow and evaluate risk of flooding in the Neuse River, North Carolina considering future climatic scenarios, and comparing them with an existing Federal Emergency Management Agency study. The cumulative distribution function transformation method was adopted for bias correction to reduce the uncertainty present in the Coupled Model Intercomparison Project Phase 6 (CMIP6) streamflow data. To calculate 100-year and 500-year flood discharges, the Generalized Extreme Value (L-Moment) was utilized on bias-corrected multimodel ensemble data with different climate projections. Out of all projections, shared socio-economic pathways (SSP5-8.5) exhibited the maximum design streamflow, which was routed through a hydraulic model, the Hydrological Engineering Center’s River Analysis System (HEC-RAS), to generate flood inundation and risk maps. The result indicates an increase in flood inundation extent compared to the existing study, depicting a higher flood hazard and risk in the future. This study highlights the importance of forecasting future flood risk and utilizing the projected climate data to obtain essential information to determine effective strategic plans for future floodplain management.

Every Year, flooding causes a calamitous impact on the people, economy, and environment all over the world. In recent years, the flood-related damages have been increasing in the United States regardless of several investments in the flood control measures. Floodplain mapping is an important tool for management that aids in the planning of infrastructures within the floodplain zone. With the magnifying effects of climate change on the hydrological cycle the study of floodplain is becoming a key tool in the water management. Federal Emergency Management Agency has recently updated their floodplain standard as per the presidential executive order 2015 on the Federal Flood Risk Management Standard. This study incorporates the newly updated floodplain mapping standard in the flood risk assessment of approximately 11.2 km stretch of the Patapsco River near Ellicott City. Hydrologic Engineering Center’s River Analysis System (HEC-RAS) with the conjunction of geographical information systems were used in the floodplain analysis. The different return period flows (2, 5, 10, 25, 50, 100, and 500) were used from the frequency analysis. These flows were routed through the selected reach of Patapsco River and the vulnerability assessment of the nearby existing infrastructures was conducted. This study can assist the decision makers and planner for the implementation of flood protection measures near the Ellicott City.

The spatiotemporal hydrologic variability over different regions of the contiguous United States poses the risk of droughts and floods. Understanding the historic variations in streamflow can help in accessing future hydrologic conditions. The current study investigates the historic changes in the streamflow within the climate regions of the continental United States. The streamflow records of 419 unimpaired streamflow stations were grouped into seven climate regions based on the National Climate Assessment, to evaluate the regional changes in both seasonal streamflow and yearly streamflow percentiles. The non-parametric Mann–Kendall test and Pettitt’s test were utilized to evaluate the streamflow variability as a gradual trend and abrupt shift, respectively. The Walker test was performed to test the global significance of the streamflow variability within each climate region based on local trend and shift significance of each streamflow station. The study also evaluated the presence of serial correlation in the streamflow records and its effects on both trend and shift within the climate regions of the contiguous United States for the first time. Maximum variability in terms of both trend and shift was observed for summer as compared to other seasons. Similarly, a greater number of stations showed streamflow variability for 5th and 50th percentile streamflow as compared to 95th and 100th percentile streamflow. It was also observed that serial correlation affected both trends and steps, while accounting for the lag-1 autocorrelation improved shift results. The results indicated that the streamflow variability has more likely occurred as shift as compared to the gradual trend. The outcomes of the current result detailing historic variability may help to envision future changes in streamflow. The current study may favor the water managers in developing future decisions to resolve the issues related to the streamflow variability in flood and drought-prone regions.

The current research is a partnering effort between Southern Illinois University Carbondale and City of Las Vegas to assess the vulnerability to drought, extreme heat, and extreme precipitation. This study focuses on precipitation and usesdifferent climate scenarios from the high-resolution North American Regional Climate Change Assessment Program (NARCCAP) climate model data to evaluate the existing stormwater infrastructure of the Gowan Watershed in the Las Vegas valley. Six NARCCAP modelsconsidered in the study have shown the Gamma distribution as the best fitted from Kolmogorov Smirnov best fit test. Delta change method is adopted to quantify the effect of climate change on storm depth. U.S. Army Corps of Engineers HEC-HMS model is used to evaluate the changes in peak flow, storage, and outflow within the watershed. The findings of the analysis show that the drainage facility of the study area is vulnerable to the related climate change impacts. This study helps to quantify the effect of climate change on design storm depth of urban watershed.

The hydrologic response of a watershed mostly depends on factors such as land use, soil type, and climatic inputs. Watershed modeling requires information on several soil properties, such as, texture, taxonomy, soil moisture, number of layers, and hydraulic conductivity. Several models are available that allow users to simulate the streamflow for a particular watershed using land use, topography, soil properties, and weather data. Better understanding of the future streamflows and water quality is essential for the long-term planning and management of water resources. The prediction of future flows and other hydrological parameters can be performed using different available modeling tools. Over the years, modeling of a watershed has significantly developed with the introduction of different sets of soil data such as Soil Survey Geographic (SSURGO) and State Soil Geographic (STATSGO). Both SSURGO and STATSGO data are compatible with GIS-enabled interfaces and can be used in both distributed and lumped hydrologic models. Soil and water assessment tool (SWAT) is one such tool that allow the use of soil properties data to estimate the runoff process of a watershed. The predictability of hydrological models vary significantly with the variation in input data resolution. The primary objective of this study was to compare the SWAT-simulated outputs: stream flow; and water quality parameters, for SSURGO and STASTGO data. The study was performed in the watershed of Lower Cumberland-Sycamore in Tennessee. The simulation results has demonstrated that the effectiveness of the model prediction depends mostly on the type and quality of input soil data, and suggested that the higher resolution data yields better model results when compared with observed data.