Increase In Precipitation Intensity Research Articles

The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble

There is a general lack of information about the potential effects of 1.5, 2 or more degrees of global warming on the regional climates within Africa, and most studies that address this use data from coarse resolution global models. Using a large ensemble of CORDEX Africa simulations, we present a pan-African overview of the effects of 1.5 and 2 °C global warming levels (GWLs) on the African climate. The CORDEX simulations, consistent with their driving global models, show a robust regional warming exceeding the mean global one over most of Africa. The highest increase in annual mean temperature is found over the subtropics and the smallest one over many coastal regions. Projected changes in annual mean precipitation have a tendency to wetter conditions in some parts of Africa (e.g. central/eastern Sahel and eastern Africa) at both GWLs, but models’ agreement on the sign of change is low. In contrast to mean precipitation, there is a consistent increase in daily precipitation intensity of wet days over a large fraction of tropical Africa emerging already at 1.5 °C GWL and strengthening at 2 °C. A consistent difference between 2 °C and 1.5 °C warmings is also found for projected changes in annual mean temperature and daily precipitation intensity. Our study indicates that a 0.5 °C further warming (from 1.5 °C–2 °C) can indeed produce a robust change in some aspects of the African climate and its extremes.

Analysis of the Long-term Precipitation Trend in Illinois and Its Implications for Agricultural Production

Climate change is expected to modify the hydrological cycle resulting in a change in the amount, frequency, and intensity of surface precipitation. How the future hydrological pattern will look is uncertain. Climate change is expected to bring about intense periods of dryness and wetness, and such behavior is expected to be difficult to predict. Such uncertainty does not bode well for the agricultural systems of the United States (US) Midwest that are reliant on natural precipitation systems. Therefore, it is necessary to analyze the behavior of precipitation during the cropping period. The manifestation of global-warming-related changes has already been reported for the last couple of decades and more so in the current decade. Thus, precipitation data from the recent past can provide vital information on what is about to come. In this study, the precipitation data of Illinois, a Midwestern state of the US with rain-fed agriculture, was analyzed with a focus on the climate dynamics during the cropping period. It was observed that even though there has been some increase in the annual precipitation amount (+1.84 mm/year) due to the increase in precipitation frequency and intensity, such change happened outside of the cropping period, thereby ensuring that climate change has not manifested itself during the cropping period.

Understanding the Dynamics of Future Changes in Extreme Precipitation Intensity

AbstractClimate model projections of extreme precipitation intensity depend heavily on the region: some regions will experience exceptionally strong increases in extreme precipitation intensity, while other regions will experience decreases in extreme precipitation intensity. These regional variations are closely related to regional changes in large‐scale ascent during extreme precipitation events—that is, “extreme ascent”—but the drivers of extreme ascent changes remain poorly understood. Using output from a large ensemble of the Canadian Earth System Model version 2, we show that subtropical changes in extreme ascent likely result from changes in the horizontal scale of ascending anomalies, which are in turn associated with changes in vertical stability. Near the equator, changes in the seasonal mean circulation may be an important factor influencing extreme ascent, but this finding is model dependent.

Projected changes in extreme precipitation over Scotland and Northern England using a high-resolution regional climate model

The UK Met Office has previously conducted convection-permitting climate simulations over the southern UK (Kendon et al. in Nat Clim Change 4:570–576, 2014). The southern UK simulations have been followed up by a new set of northern UK simulations using the same model configuration. Here we present the mean and extreme precipitation projections from these new simulations. Relative to the southern UK, the northern UK projections show a greater summertime increase of return levels and extreme precipitation intensity in both 1.5,hbox {km} convection-permitting and 12,hbox {km} convection-parameterised simulations, but this increase is against a backdrop of large decreases in summertime mean precipitation and precipitation frequency. Similar to the southern UK, projected change is model resolution dependent and the convection-permitting simulation projects a larger intensification. For winter, return level increases are somewhat lower than for the southern UK. Analysis of model biases highlight challenges in simulating the diurnal cycle over high terrain, sensitivity to domain size and driving-GCM biases, and quality issues of radar precipitation observations, which are relevant to the wider regional climate modelling community.

Precipitation variability over Northwest Himalaya from ∼4.0 to 1.9 ka BP with likely impact on civilization in the foreland areas

We present a stalagmite based high resolution climatic record between ∼4.0 and 1.9 ka BP from Dharamjali Cave in Pithoragarh (Kumaun Himalaya), an area which is influenced primarily by the Indian Summer Monsoon (ISM) and supplemented by the Indian Winter Monsoon (IWM). The chronology of the 41.5 cm long DH-1 stalagmite was constructed using a StalAge model on six 230Th/U dates. However, some samples have higher 232Th concentrations, leading to an increase in the final age uncertainties, hence the chronology supports only the possible climatic boundaries. However, the significance of this work lies in its being one of the rare studies of speleothems to reconstruct high resolution climatic changes in the NW India for the Upper Holocene. The δ18O values, ranging between −5.3‰ and −10‰, show a large variation, compared to the areas dominated by a single monsoon, and this can be ascribed to the two sources of moisture (e.g., ISM and IWM) in the study area during the Upper Holocene. The sample consists of aragonite except for two sections of calcite growth from 0–7.3 cm and 8.5–13.5 cm from the top. The climatic reconstruction, within the age uncertainties, indicates strengthened precipitation from 4.0 ka BP with a sharp drop (>−2‰) in δ18O values, peaking at ∼3.7 ka BP. A gradual decline in precipitation is observed from ∼3.7 to 3.0 ka BP with possible droughts, centered at ∼3.4, ∼3.2 and ∼3.0 ka BP. Subsequently, climatic amelioration took place between ∼3.0 and 2.9 ka BP, showing fluctuating trend in δ18O values with comparatively more rainfall, possibly generated by the IWM in the form of thunderstorms and hailstorms from ∼2.9 to 2.7 ka BP. Precipitation declined from ∼2.7 to 2.4 ka BP with a decadal scale major drought event, strongest in the present data set, at ∼2.5–2.4 ka BP, whereas, an abrupt drop in stalagmite δ18O values from ∼2.4 to 2.3 ka BP points to increased precipitation intensity. Thereafter, the precipitation gradually decreased until ca. 2.1 ka BP with one of the driest events at ∼2.1 ka BP. A century scale increasing trend in the precipitation intensity is observed from ∼2.1 to 2.0 ka BP, following which the precipitation again declined. Accordingly, five sudden drought events are documented, centering at ∼3.4, ∼3.2, ∼3.0, ∼2.5–2.4 and ∼2.1 ka BP. A gradual reduction in precipitation from ∼3.7 to 3.0 ka BP coincides with reduction and deurbanisation and step-wise disintegration of the Harappan civilization along the Indus-Ghaggar-Sarasvati valleys in the foreland areas of northwestern India.

Extreme precipitation linked to temperature over Japan: current evaluation and projected changes with multi-model ensemble downscaling

Recent studies have revealed that an increase in surface air temperature elevates the intensity of extreme precipitation associated with the increase of water vapor in the atmosphere, according to the principle of the Clausius–Clapeyron (CC) relationship. In this study, (1) we have verified the dependence of extreme precipitation intensity on temperature (CC relationship) under current climate and (2) investigated the projected changes of the CC relationship over Japan by using multi-model ensemble downscaling experiments of three Regional Climate Models (RCMs) (NHRCM, NRAMS, WRF) forced by JRA25, as well as three General Circulation Models (GCMs) (CCSM4, MIROC5, MRI-CGCM3). Simulated extreme precipitation linked to temperatures from ensemble experiments coincides with observations that place peak temperatures around 19–22 °C. Climate scenarios (RCP4.5) of the late twenty-first century suggest a 2 °C increase of 2 m air temperature, an increase in precipitation intensities above 15 mm/day, and a decrease in weaker precipitation intensities of 10–15 mm/day. The projected change rate of the mean precipitation intensities per mean change in air temperature over Japan is found to be 2.4%/°C. Extreme precipitation intensity increases with temperatures up to 22 °C in future climate scenarios, while the peak is 20 °C for the current climate. Extreme precipitation intensities at higher percentiles are projected to have larger rates of increase (3–5%/°C in the current climate and 4–6%/°C in the future climate scenarios). A decrease of precipitation intensity at higher temperatures relates to water vapor availability. An insufficient water vapor supply for saturation at higher temperatures can lead to a decrease in cloud formation and extreme precipitation.

A new mechanism for warm-season precipitation response to global warming based on convection-permitting simulations

Climate models project increasing precipitation intensity but decreasing frequency as greenhouse gases increase. However, the exact mechanism for the frequency decrease remains unclear. Here we investigate this by analyzing hourly data from regional climate change simulations with 4 km grid spacing covering most of North America using the Weather Research and Forecasting model. The model was forced with present and future boundary conditions, with the latter being derived by adding the CMIP5 19-model ensemble mean changes to the ERA-interim reanalysis. The model reproduces well the observed seasonal and spatial variations in precipitation frequency and histograms, and the dry interval between rain events over the contiguous US. Results show that overall precipitation frequency indeed decreases during the warm season mainly due to fewer light-moderate precipitation (0.1 10 mm/h) events increase. Dry spells become longer and more frequent, together with a reduction in time-mean relative humidity (RH) in the lower troposphere during the warm season. The increased dry hours and decreased RH lead to a reduction in overall precipitation frequency and also for light-moderate precipitation events, while water vapor-induced increases in precipitation intensity and the positive latent heating feedback in intense storms may be responsible for the large increase in intense precipitation. The size of intense storms increases while their number decreases in the future climate, which helps explain the increase in local frequency of heavy precipitation. The results generally support a new hypothesis for future warm-season precipitation: each rainstorm removes ≥7% more moisture from the air per 1 K local warming, and surface evaporation and moisture advection take slightly longer than currently to replenish the depleted moisture before the next storm forms, leading to longer dry spells and a reduction in precipitation frequency, as well as decreases in time-mean RH and vertical motion.

Effects of Precipitation and Topography on Total Phosphorus Loss from Purple Soil

The Sichuan Basin is the main agricultural production area of the upper reaches of the Yangtze River and is also an extremely important ecological area because it is rich in biodiversity and has complex and diverse landscape types. The dominant soil type, purple soil, is prone to rapid soil erosion and weathering processes because it is shallow and rich in phosphorus and other nutrients. Field experiments were conducted to reveal the effects of precipitation and topography characteristics on nonpoint source pollutants from purple soil. The results showed that total phosphorus (TP) load and TP concentration both increased with increasing rainfall amount, and there was an initial time of runoff and sediment yield before runoff generation. Moreover, the TP load generally increased with precipitation intensity as setting a coincident value of rainfall amount; however, the difference between TP load at 30 and 60 mm/h was minimal as was the difference between 90 and 120 mm/h. Similarly, TP concentration increased with increasing precipitation intensity. In terms of topographical conditions, TP load increased with increasing gradient, but began to decline when the gradient was about 20°, which indicates that 20° is the critical gradient for TP loss. There was a significant positive correlation between gradient and TP concentration when the gradient was <15°, whereas the increase in TP concentration slowed as the gradient increased.

A savanna response to precipitation intensity.

As the atmosphere warms, precipitation events are becoming less frequent but more intense. A three-year experiment in Kruger National Park, South Africa, found that fewer, more intense precipitation events encouraged woody plant encroachment. To test whether or not these treatment responses persisted over time, here, we report results from all five years of that experiment. Grass growth, woody plant growth, total fine root number and area and hydrologic tracer uptake by grasses and woody plants were measured in six treated plots (8 m by 8 m) and six control plots. Treatment effects on soil moisture were measured continuously in one treated and one control plot. During the fourth year, increased precipitation intensity treatments continued to decrease water flux in surface soils (0–10 cm), increase water flux in deeper soils (20+ cm), decrease grass growth and increase woody plant growth. Greater root numbers at 20–40 cm and greater woody plant uptake of a hydrological tracer from 45–60 cm suggested that woody plants increased growth by increasing root number and activity (but not root area) in deeper soils. During the fifth year, natural precipitation events were large and intense so treatments had little effect on precipitation intensity or plant available water. Consistent with this effective treatment removal, there was no difference in grass or woody growth rates between control and treated plots, although woody plant biomass remained higher in treated than control plots due to treatment effects in the previous four years. Across the five years of this experiment, we found that 1) small increases in precipitation intensity can result in large increases in deep (20–130 cm) soil water availability, 2) plant growth responses to precipitation intensity are rapid and disappear quickly, and 3) because woody plants accumulate biomass, occasional increases in precipitation intensity can result in long-term increases in woody plant biomass (i.e., shrub encroachment). While results are likely to be site-specific, they provide experimental evidence of large ecohydrological responses to small changes in precipitation intensity.

Application of physical scaling towards downscaling climate model precipitation data

Physical scaling (SP) method downscales climate model data to local or regional scales taking into consideration physical characteristics of the area under analysis. In this study, multiple SP method based models are tested for their effectiveness towards downscaling North American regional reanalysis (NARR) daily precipitation data. Model performance is compared with two state-of-the-art downscaling methods: statistical downscaling model (SDSM) and generalized linear modeling (GLM). The downscaled precipitation is evaluated with reference to recorded precipitation at 57 gauging stations located within the study region. The spatial and temporal robustness of the downscaling methods is evaluated using seven precipitation based indices. Results indicate that SP method-based models perform best in downscaling precipitation followed by GLM, followed by the SDSM model. Best performing models are thereafter used to downscale future precipitations made by three global circulation models (GCMs) following two emission scenarios: representative concentration pathway (RCP) 2.6 and RCP 8.5 over the twenty-first century. The downscaled future precipitation projections indicate an increase in mean and maximum precipitation intensity as well as a decrease in the total number of dry days. Further an increase in the frequency of short (1-day), moderately long (2–4 day), and long (more than 5-day) precipitation events is projected.

Past and future trends of hydroclimatic intensity over the Indian monsoon region

AbstractThe hydroclimatic intensity index (HY‐INT) is a single index that quantitatively combines measures of precipitation intensity and dry spell length, thus providing an integrated response of the hydrological cycle to global warming. The HY‐INT index is a product of the precipitation intensity (PINT, intensity during wet days) and dry spell length (DSL). Using the observed gridded rainfall data sets of 1951–2010 period, the changes in HY‐INT, PINT, and DSL over the Indian monsoon region have been examined in addition to changes in maximum consecutive dry days (MCD). We have also considered 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models for examining the changes in these indices during the present‐day and future climate change scenarios. For climate change projections, the Representative Concentration Pathway (RCP) 4.5 scenario was considered. The analysis of observational data during the period 1951–2010 suggested an increase in DSL and MCD over most of central India. Further, statistically significant (95% level) increase in HY‐INT is also noted during the period of 1951–2010, which is mainly caused due to significant increase in precipitation intensity. The CMIP5 model projections of future climate also suggest a statistically significant increase in HY‐INT over the Indian region. Out of the 10 models considered, seven models suggest a consistent increase in HY‐INT during the period of 2010–2100 under the RCP4.5 scenario. However, the projected increase in HY‐INT is mainly due to increase in the precipitation intensity, while dry spell length (DSL) showed little changes in the future climate.

Potential changes in the number of wet days and its effect on future intense and annual precipitation in northern Oman

AbstractThe changes in the number of wet days (NWD) in Oman projected by climate models was analyzed, focusing mostly on variation of precipitation intensity and its effect on total annual precipitation (PTOT) in the future. The daily precipitation records of 49 gage stations were divided into five regions. Of the five general circulation models studied, two of them were selected based on their performance to simulate local-scale precipitation characteristics. All regions studied, except the interior desert region of the country, could experience fewer wet days in the future, with the most significant decreases estimated in southern Oman. The contribution from the cold frontal troughs to the PTOT in the northeast coastal region would decrease from 85% in the 1985–2004 period to 79% during the 2040–2059 period and further decrease to 77% during the 2080–2099 period. In contrast, results depict enhanced tropical cyclone activities in the northeast coastal region during the post-monsoon period. Despite the decreases in the NWD, PTOT in all regions would increase by 6–29% and 35–67% during the 2040–2059 and 2080–2099 periods, respectively. These results, therefore, show that increases in precipitation intensity dominate the changes in PTOT.

Less warming projected during heavy winter precipitation in the Cascades and Sierra Nevada

ABSTRACTLocal rates of warming from increased greenhouse gas concentrations can be different during heavy precipitation than during other times. This variable warming can influence precipitation extremes through the Clausius–Clapeyron relationship and modulate the rate of snowfall decline. Large ensembles of simulations from a regional climate model were used to project, with high signal‐to‐noise ratio, changes in the daily winter temperature versus precipitation intensity relationship from the contemporary period to a mid‐21st century scenario over the Cascades and Sierra Nevada of the United States. Warming rates decreased with increasing precipitation intensity over all montane regions, with the strongest relationship in the northern Cascades (1.2 °C less warming at 100 mm day−1 than at trace amounts). The relationship may be linked to the projected north Pacific meridional warming gradient, as the moisture of the largest precipitation events originates at lower latitudes where warming is less, though other factors may contribute.

Effects of rainfall intensity and intermittency on woody vegetation cover and deep soil moisture in dryland ecosystems

Identifying the relationship between the stochastic daily rainfall regime and the dynamics of plants and soil moisture is fundamental for the sustainable management of dryland ecosystems in a context of global climate change. An eco-hydrological model that couples the dynamics of woody vegetation cover and deep soil moisture (typically with a depth interval of 30–150cm) was used to investigate the effect of stochastic intensity and the intermittency of precipitation on soil moisture in this deep interval, which affects woody vegetation cover. Our results suggest that the precipitation intensity and intermittency play an important role in the dynamics of wood vegetation cover and deep soil moisture. In arid and semiarid regions, as the annual precipitation increased, the rate of woody vegetation cover increased as a power-law function, and the deep soil moisture increased exponentially. For a given annual rainfall, there were positive correlations between the rainfall intensity (or rainfall intermittency) and both the woody vegetation cover and deep soil moisture. The positive correlations between wood vegetation cover and both rainfall intensity and intermittency may decrease with increases in the precipitation intensity or precipitation intermittency. The positive correlations between deep soil moisture and both rainfall intensity and rainfall intermittency increase as the precipitation intensity or precipitation intermittency increases. Moreover, these positive correlations may increase with increases in the mean annual rainfall. Our results emphasize the importance of daily precipitation variations in controlling the responses of woody vegetation cover and deep soil moisture to climate variations in arid and semiarid regions. Our model can aid the understanding of rainfall processes and indicates that increases in rainfall intensity or rainfall intermittency may lead to an increase in woody vegetation cover and deep soil moisture given an invariable annual rainfall regime in dryland ecosystems.

Potential Impact of Climate Change on Rainfall Intensity-Duration-Frequency Curves in Roorkee, India

Intensification and frequency of hydrologic events are attributed to climate change and are expected to increase in coming future. Intensity-Duration-Frequency (IDF) curves quantify the extreme precipitation and are used extensively to assess the return periods of rainfall events. It is expected that climate change will modify the occurrence of extreme rainfall events. Thus a need of updating IDF curves arises under the climate change scenario. This paper aims at updating the IDF curves for a typical Indian town using an ensemble of five General Circulation Models (GCMs) for all the Representative Concentration Pathways (RCP) scenarios. Sub-daily maximum intensities (15-, 30-, 45-, 60-, 120-, and 180 min) were obtained from the observed records. Equidistance quantile method was used to study the relationships between the historical and projected GCM data, and the historical GCM and observed sub-daily data. This relationship was used to obtain projected sub-daily intensities. The IDF curves were developed using observed and projected data. Analysis of the curves indicated increase in precipitation intensities for all the RCP scenarios. It was also found that intensities of all return periods increases with intensifying RCP scenarios. The variation in the intensities across the GCMs was attributed to the driving forces considered in a particular GCM.

Groundwater Level Trends and Drivers in Two Northern New England Glacial Aquifers

AbstractWe evaluated long‐term trends and predictors of groundwater levels by month from two well‐studied northern New England forested headwater glacial aquifers: Sleepers River, Vermont, 44 wells, 1992‐2013; and Hubbard Brook, New Hampshire, 15 wells, 1979‐2004. Based on Kendall Tau tests with Sen slope determination, a surprising number of well‐month combinations had negative trends (decreasing water levels) over the respective periods. Sleepers River had slightly more positive than negative trends overall, but among the significant trends (p < 0.1), negative trends dominated 67 to 40. At Hubbard Brook, negative trends outnumbered positive trends by a nearly 2:1 margin and all seven of the significant trends were negative. The negative trends occurred despite generally increasing trends in monthly and annual precipitation. This counterintuitive pattern may be a result of increased precipitation intensity causing higher runoff at the expense of recharge, such that evapotranspiration demand draws down groundwater storage. We evaluated predictors of month‐end water levels by multiple regression of 18 variables related to climate, streamflow, snowpack, and prior month water level. Monthly flow and prior month water level were the two strongest predictors for most months at both sites. The predictive power and ready availability of streamflow data can be exploited as a proxy to extend limited groundwater level records over longer time periods.

A multi-model climate response over tropical Africa at +2 °C

The impact of a +2°C global warming on temperature and precipitation over tropical Africa is examined, based on an ensemble of 12 regional climate model scenario simulations. These 12 scenarios are re-phased so that they all correspond to the same global warming of 2°C with respect to pre-industrial conditions. The continental temperature increase is above the global average. If heat waves are defined with the same temperature threshold in the reference climate and in the scenario, their frequency increases by a factor of 10. When the temperature threshold is adapted to future conditions, there is still a slight increase in frequency. The average precipitation does not show a significant response, due to model-to-model spread. However two compensating phenomena occur, which are robust among the models: (a) the number of rain days decreases whereas the precipitation intensity increases, and (b) the rain season occurs later during the year with less precipitation in early summer and more precipitation in late summer. Simulated daily temperature and precipitation data are combined in two impact models, one for the hydrology of the Nile and Niger basins, one for the food security of the different countries. They show that the main feature of the climate change is not a continuous trend signal, but an alternation of dry and wet decadal to multidecadal episodes.

Resolution dependence of precipitation statistical fidelity in hindcast simulations

AbstractNumerous studies have shown that atmospheric models with high horizontal resolution better represent the physics and statistics of precipitation in climate models. While it is abundantly clear from these studies that high‐resolution increases the rate of extreme precipitation, it is not clear whether these added extreme events are “realistic”; whether they occur in simulations in response to the same forcings that drive similar events in reality. In order to understand whether increasing horizontal resolution results in improved model fidelity, a hindcast‐based, multiresolution experimental design has been conceived and implemented: the InitiaLIzed‐ensemble, Analyze, and Develop (ILIAD) framework. The ILIAD framework allows direct comparison between observed and simulated weather events across multiple resolutions and assessment of the degree to which increased resolution improves the fidelity of extremes. Analysis of 5 years of daily 5 day hindcasts with the Community Earth System Model at horizontal resolutions of 220, 110, and 28 km shows that: (1) these hindcasts reproduce the resolution‐dependent increase of extreme precipitation that has been identified in longer‐duration simulations, (2) the correspondence between simulated and observed extreme precipitation improves as resolution increases; and (3) this increase in extremes and precipitation fidelity comes entirely from resolved‐scale precipitation. Evidence is presented that this resolution‐dependent increase in precipitation intensity can be explained by the theory of Rauscher et al. (), which states that precipitation intensifies at high resolution due to an interaction between the emergent scaling (spectral) properties of the wind field and the constraint of fluid continuity.

A U.S.‐based analysis of the ability of the Clausius‐Clapeyron relationship to explain changes in extreme rainfall with changing temperature

AbstractNumerous papers have shown links between >99th percentile hourly precipitation and daily temperature (Pextreme versus T), often explained using the Clausius‐Clapeyron (CC) relationship. The CC relationship predicts an approximately 7% increase in precipitation intensity per degree celsius. However, recent analyses indicate that the Pextreme versus T rate can be larger than the CC prediction. In this work, we analyze the Pextreme versus T rate with an automated method across the contiguous U.S. using station data aggregated on a 161 km grid. To evaluate controls on Pextreme versus T, we isolate convective storms to evaluate whether greater than CC rates are due to the transition between storm types or are a feature of convective storms at high T. We repeat the analysis using dew point to assess whether T control on extreme P is indeed a matter of moisture availability. When evaluated using both T and dew point, the northeastern U.S. is most likely to exhibit a greater than predicted Pextreme versus T rate (57% of the region when using T). At 56% of these points, the > CC rates appeared to occur entirely because of a transition between frontal and convective storms. At 30% of these sites, a greater than CC relationship appeared to occur entirely because of greater than CC scaling in convective intensity. At 11% of sites neither was found to be significant, and at 3% both were found to contribute significantly. This analysis suggests that > CC scaling is not prevalent everywhere in the contiguous U.S., and in regions where it does occur, it can be due to multiple causes.

Sensitivity of Flood-Depth Frequency to Watershed-Runoff Change and Sea-Level Rise Using a One-Dimensional Hydraulic Model

AbstractClimate change and sea-level rise are expected to alter the likelihood of extreme events, such as floods, within the design lifetime of infrastructure components. Critical civil infrastructure facilities, including wastewater treatment, transportation, and energy, need site-specific flood contingency plans that reflect the effects of changing climate. This study developed a sensitivity analysis method to assess future flood risk by estimating flood frequency under conditions of higher sea level and streamflow response to increased precipitation intensity. The method was applied to an ungauged location on a tidal estuary in the Mid-Atlantic region as a case study. One-dimensional (1D) unsteady flow analysis using a hydraulic analysis software developed by the U.S. Army Corps of Engineers was used to predict discharge and water surface elevation along the estuary reach, subject to prescribed boundary conditions of upstream discharge and downstream water surface elevation. A current-climate flood-dep...