Storm Duration Research Articles

The effects of coastal marsh geometry and surge scales on water level attenuation

Coastal wetlands are an effective natural and nature-based feature to mitigate coastal flood hazards. While the sheltering and attenuation offered by wetlands are recognized, the protection level varies based on wetland and storm characteristics. Here we focus on the effects of the spatial scales of the coastal wetlands (i.e., channel geometry, marsh elevation-gradient) and the temporal scales of storm forcing (i.e., storm surge amplitude and duration) on peak water level attenuation. The study was conducted by performing hydrodynamic simulations on an idealized marsh geometry. One hundred seventy-one hydrodynamic simulations were conducted by varying wetland features under variable hydrodynamic forcing. Increased tidal channel area enhances water flow across marshes by reducing the capacity of vegetated platforms to resist propagation of a storm surge. The level of surge attenuation and channel area shows a non-linear relationship. Storm scales also affect surge attenuation for a given channel geometry. Higher amplitudes and lower surge durations provide greater attenuation of peak water levels. The level of attenuation and surge scales also show a non-linear correlation. A multivariate scaling relationship was developed that successfully integrates the combined effects of channel geometry and surge scales on water level attenuation by salt marsh. This research provides guidance to engineers and coastal managers on salt marsh's flood hazard reduction benefits.

Quantification of the Cross-helicity Turbulent Cascade in Compressible MHD Simulations

In plasma turbulence, energy and cross helicity are transferred across scales at a constant rate as a consequence of nonlinear interactions. In incompressible magnetohydrodynamics (MHD), the energy cascade rate of both quantities can be computed by means of the temporal evolution of second-order structure functions, known as Karman–Howarth–Monin (KHM) equations. In the present work, we derive the KHM equation to compute the energy cascade rate of cross helicity in compressible MHD. Using three-dimensional direct numerical simulations, we validate the equation and use it to measure the cross-helicity turbulence properties. Our results show a slower development of the cross-helicity cascade with respect to the energy one and the presence of inverse cascades of energy and cross helicity at large scales when in the presence of a strong mean field. We propose the relation of these phenomena with the longer duration of geomagnetic storms after the arrival of solar winds with large cross helicity and the observation of patchy inertial ranges displaying positive and negative cascade rates for certain solar wind intervals.

In the shadow of the dam – Hydrology of the Little Conemaugh river and its South Fork, with insights about past and future flooding

The Little Conemaugh River watershed and its South Fork sub-basin figure prominently in historical flooding of Johnstown, Pennsylvania and nearby communities with catastrophic flooding in 1889, 1936, and 1977 (reviewed herein). Historical stream gage data and data from a new gage on the South Fork (established via a novel, portable cableway system) are used with Nexrad rainfall data to assess watershed response and provide novel analysis of flood hydrology in the Little Conemaugh basin and the sub-basin. Using unit hydrograph estimates for longer duration storms (>8 h) and different baseflow conditions, we probe possible effects of several design storms, including those stemming from a hurricane remnant scenario (Agnes in 1972) and 50-, 100-, and 500-year 12-hour precipitation depths. The unit hydrographs provided peak discharge (Qpeak) estimates for 1977 (the only flood event with available hourly rainfall data) that are in good agreement with empirical peak discharges.Significant channel improvements completed in 1943 were designed to carry the largest known natural flow on record at that time (1936 Qpeak). Preliminary results from design storm scenarios indicate the need for a careful evaluation of extreme discharges and their return periods (including snowmelt-related contributions), as future flood levels in Johnstown may occur more frequently than originally thought. The 1977 flood, which triggered 7 dam failures and eclipsed 1936 Qpeak, resulted from less than 40% the estimated probable maximum precipitation (PMP) for a 12-hour storm. Peak discharges of similar magnitude would have ensued in 1972 had remnants of Hurricane Agnes tracked slightly westward. Flooding and infrastructure problems could be compounded for storms of 24-hour or longer durations, similar to record flooding seen in central Pennsylvania and New York in 1972. Flood recurrence, emergency procedures, and dam safety (particularly, spillway capacity in the Little Conemaugh basin and surrounding region) should likely be reassessed and protective early-warning measures (ineffective in 1977) implemented for the people of Johnstown.

Hydrologic Sensitivities and ENSO Variability Across Hydrological Regimes in Central Chile (28°–41°S)

AbstractThere is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Pacific and related impacts on the precipitation regime in Chile; nonetheless, many aspects of the hydrological propagation and temperature responses to ENSO remain unclear in this region. We examine fluctuations across 59 near‐natural catchments in central Chile (28°–41°S) under contrasting ENSO phases during the period 1981–2019. Our results show statistically significant ENSO‐related hydroclimatic anomalies in almost all watersheds analyzed, which confirms the major influence of ENSO within this domain. By comparing El Niño phases against La Niña, we observe generally wetter conditions, warmer winters, cooler late springs, lower (higher) runoff ratios in snowmelt‐driven (rainfall‐driven) basins, and longer storm durations while storm frequencies (i.e., number of events of consecutive days with precipitation) are preserved. Additionally, low (high) elevation catchments are related to positive (negative) streamflow sensitivities to winter temperature, which increase in magnitude with the evaporative index; besides, catchments with sharp warm‐and‐dry conditions yield largely negative sensitivities to late spring temperature. Further, positive streamflow anomalies in rainfall‐driven catchments are explained by temperature and precipitation ENSO‐related amplitudes (El Niño minus La Niña) that separately favor streamflow; however, in mixed regimes and snowmelt‐driven basins these results are spatially scattered. Hence, this study supports that meteorological, hydrological, and physiographic attributes modulate the translation of climate variability into river hydrology. The results presented here unravel the joint effects of precipitation and seasonal temperature fluctuations through different hydrological regimes, across a region that encloses populated cities and water‐intensive activities.

The effect of sequential storms on the performance of homogeneous berm breakwaters

Reshaping of homogeneous berm breakwaters have been experimentally investigated using 2D physical tests. Berm recession depends on storm duration in addition to breakwater geometry and other storm parameters such as significant wave height and peak period. Furthermore, a berm breakwater may experience some recessions prior to exposing to a design storm for which the breakwater is designed. In this study, 109 tests have been conducted totally to investigate the enhancement of berm recession during design storms and also to study the effect of sequential storms on the ultimate berm recession during the life span of berm breakwaters. The measured cumulative recessions have been compared with direct recessions obtained from a breakwater with no initial reshaping. According to the results, the effect of earlier sea states on final berm recession depends on the design stability index and it can be neglected only if the design storm is too weak ( H 0 T 0 < 40 ) or it is too strong ( H 0 T 0 > 80 ). For weak design storms, earlier reshaping is negligible, while for strong design storm, the final reshaped profile will be governed only by such design storms regardless of earlier sea states. The results show that the predicted berm recession against design storms can be maximum 10% less than the actual recession in the case of missing the effect of earlier sea states. Since this conclusion is valid for both statically and dynamically stable berm breakwaters (the maximum value occurs around H 0 T 0 = 70 ), it is suggested finally that designers consider 10% more recession than the predicted values by existing design formulae to be sure about the endurance of berm width against the cumulative berm recessions during design life of reshaping berm breakwaters. The observations showed also that this width can efficiently dissipate the wave energy and protect underneath layers. • Homogenous reshaping berm breakwaters are studied using 109 physical tests. • A new formula is proposed to calculate berm recession during storms as a function of modified stability index. • Cumulative recession during design life of berm breakwater is investigated and an applicable suggestion is provided. • A modified stability index is proposed for measuring the influence of design storms.

Aspects related to variability of radiative cooling by NO in lower thermosphere, TEC and O/N2 correlation, and diffusion of NO into mesosphere during the Halloween storms

Nitric Oxide is a very important trace species which plays a significant role acting as a natural thermostat in Earth’s thermosphere during strong geomagnetic activity. In this paper, we present various aspects related to the variation in the NO Infrared radiative flux (IRF) exiting the thermosphere by utilizing the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/ Sounding of the Atmosphere using Broadband Emission Radiometry) observational data during the Halloween storm which occurred in late October 2003. The Halloween storm comprised of three intense-geomagnetic storms. The variability of NO infrared flux during these storm events and its connection to the strength of the geomagnetic storms were found to be different in contrast to similar super storms. The connection between the quantum of energy outflux from the upper atmosphere into space in terms of NO IRF and the duration of storms is established. The NO radiative cooling, and the closely correlated depletion in O/N2 ratio are controlled by the Joule heating intensity (proxied by AE-index). The collisional excitation rate of NO, calculated using the modelled datasets of WACCM-X (Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension), correlates well with the observed pattern of radiative emission by NO. Observational datasets from TIMED/GUVI (Global Ultra-Violet Imager) and MIT Haystack observatory madrigal GNSS (Global navigation satellite system) total electron content (TEC) database shows that the TEC and O/N2 enhancement in low-mid northern hemispheric latitudes are mainly controlled by the z-component of Interplanetary magnetic field (IMF-Bz). The penetration of eastward electric field during the storm events is found to be responsible for the overall enhancement of TEC. The contribution of enhanced day-side TEC in observed variation of O/N2 ratio by GUVI is also reported. It is also seen that during substorms related events the night-time polar region experiences more cooling due to NO than the daytime polar region. The connections between the mid- and low-latitude enhancement in NO IRF with the propagation of LSTIDs (Large-scale traveling ionospheric disturbances) in combination with the O/N2 variability, and the altitudinal variation in NO flux with the progression of the storm is also investigated. This study presents the evidence on the role of diffusion processes in the large scale enhancement of NO in the mesospheric altitudes.

Climate Change and Weather Extremes in the Eastern Mediterranean and Middle East

AbstractObservation‐based and modeling studies have identified the Eastern Mediterranean and Middle East (EMME) region as a prominent climate change hotspot. While several initiatives have addressed the impacts of climate change in parts of the EMME, here we present an updated assessment, covering a wide range of timescales, phenomena and future pathways. Our assessment is based on a revised analysis of recent observations and projections and an extensive overview of the recent scientific literature on the causes and effects of regional climate change. Greenhouse gas emissions in the EMME are growing rapidly, surpassing those of the European Union, hence contributing significantly to climate change. Over the past half‐century and especially during recent decades, the EMME has warmed significantly faster than other inhabited regions. At the same time, changes in the hydrological cycle have become evident. The observed recent temperature increase of about 0.45°C per decade is projected to continue, although strong global greenhouse gas emission reductions could moderate this trend. In addition to projected changes in mean climate conditions, we call attention to extreme weather events with potentially disruptive societal impacts. These include the strongly increasing severity and duration of heatwaves, droughts and dust storms, as well as torrential rain events that can trigger flash floods. Our review is complemented by a discussion of atmospheric pollution and land‐use change in the region, including urbanization, desertification and forest fires. Finally, we identify sectors that may be critically affected and formulate adaptation and research recommendations toward greater resilience of the EMME region to climate change.

P1183: CAR-T MORPHOLOGICAL CHARACTERISTICS AND DYNAMICS IN PERIPHERAL BLOOD, EVALUATED BY A NOVEL MICROSCOPY PLATFORM

Background: Chimeric Antigen Receptor T-cells (CAR-T) therapy becomes a preferable therapeutic approach in patients with relapsed and refractory (R/R) non-Hodgkin’s large B cell lymphomas (LBCL) who failed ≥2 therapeutic regimens. However, there are no commercial assays for routine CAR-T measurements and clinical studies often employ PCR or FACS, both expensive and relatively complicated. Detection of CAR-T in peripheral blood smear (PBS) is challenging, mostly due to the lack of data regarding their morphology prior to transfusion and the low sensitivity of currently available technologies. As oppose to the currently available digital morphology, Scopio Labs Full Field Morphology (FFM) is a novel digital microscopy platform that provides high-resolution images combined with a full field analysis, incorporating artificial intelligence capabilities, thereby enabling the detection and classification of rare cells in PBS, including CAR-T cells. Aims: The dynamics of CAR-T quantity and subtypes in PBS were evaluated, and correlated with responsiveness to treatment and treatment-related toxicities. Methods: Morphological library of CAR-T cells was established from cells obtained directly from the CAR-T transfusion-bag (Fig. 1A). FFM analysis of consecutive PBS samples obtained from 26 R/R DLBCL patients, treated either with tisagenlecleucel (tisa-cel) or axicabtagene ciloleucel (axi-cel) at the Tel Aviv Sourasky Medical Center between October 2019-October 2020 was performed. Results: We identified in the CAR-T cell transfusion bags 5 distinct CAR-T morphological sub groups prior to transfusion: regular, activated, apoptotic, multinucleated and cells in mitosis (Fig. 1A). First, 79 smears, obtained from 18 patients, were examined with the FFM platform vs the CellaVision DM1200 system. Overall, 24,247 WBC were detected by the FFM platform (average 303 cells per PBS), compared with 4,335 detected by CellaVision DM1200 system (average 54.4 cells per PBS). Detection of CAR-T was superior with the FFM platform (median difference per PBS - 2, IQR 0-6, p<0.001). Then, PBS from 26 patients, 21 (80.7%) treated with tisa-cel, and 5 (19.2%) treated with axi-cel, were analyzed by the FFM platform. The absolute number of CAR-T cells in the PBS post infusion was higher in patients treated with axi-cel (across days 1 to 15). The average numbers of total, regular, and activated CAR-T cells, measured on day 5 post CAR-T-transfusion, were all higher in patients that obtained CR vs those who did not (Fig. 1B). Longer duration of cytokine release storm (CRS) was associated with higher number of CAR-T cells with activated morphology, and a lower presence of apoptotic cells on day 14. Higher number of apoptotic cells on day 14 were associated with a deferred CRS onset, while lower number of activated morphology cells on day 14 was associated with earlier onset of CRS. There was a positive correlation between the number of cells, measured on day 7 by FACS, and time to peak of regular morphological CAR-T cells (r=0.67, p=0.034, n=10). Image:Summary/Conclusion: In this study, we show that CAR-T cells has heterogeneous morphology identified in PBS. Specific morphological features in specific days were associated with outcome and therapy related toxicities, emphasizing that CAR-T monitoring require quantitative, qualitative and repeated measurements. Thus, morphological CAR-T surveillance using FFM might serve as an available, simple and inexpensive method to provide clinically relevant insights.

Regional Analysis of Dust Day Duration in Central Iran

The duration of dust days (DDD) is one of the most important parameters that may worsen the effects of the presence of dust in the affected areas. Persistent pollution over consecutive dusty days can have particularly negative effects on the human respiratory system. The present analysis was conducted in Central Iran, where the phenomenon of dust is one of the most important problems. In this study, using dust codes recorded at 35 synoptic stations, the homogeneity of DDD across the region was investigated using the L-moments method. Then, characteristics of DDD over the period 1999–2018 were calculated. The results showed that the region is statistically homogeneous. Furthermore, Zabol and Zahdan are the stations worst affected, with the longest durations of 22 and 21 days in 2014. Additionally, the values of DDD with return periods of 5, 10, 25, and 50 years were calculated using fitted statistical distributions and kriging and mapped. Finally, using the K nearest neighbor method the most important factor affecting DDD of the spatial characteristics, including longitude, latitude, elevation, average daily temperature (tm), dew point (td), wind altitude (u), maximum wind speed (ffmax), and direction of the fastest wind (ddmax), was determined. It was found that the southeastern parts of the study area are affected by the longest dust storm duration in all return periods; over longer return periods, long dust storms are also found in the central parts, especially the central desert of Iran. Therefore, these areas should be given priority in fighting and controlling wind erosion. Furthermore, the results showed that the maximum wind speed has the greatest effect on DDD.

Analysis of Ocean Parameters as Sources of Coastal Storm Damage: Regional Empirical Thresholds in Northern Spain

This contribution aims to explore the role of oceanographic parameters on the damage caused by storms at the eastern Cantabrian coast (1996–2016). All wave storms affecting the study area were characterized in terms of several oceanographic parameters; among them, damaging storms (responsible for direct and tangible loss) were identified. Cross-referencing both databases makes it possible to find some thresholds that explain storm conditions associated with property damage. Particularly relevant are those responsible for significant and widespread damage: maximum significant offshore wave height &gt;6.5 m, maximum total water level &gt;6 m, SPI &gt; 1700 m2h, and a storm duration &gt;48 h. These values are exceptionally high, mostly exceeding the 95th percentile. A comparison has been made with other thresholds described in the literature. The concurrence of high wave height and high tidal level is crucial as the greatest damage is caused by the combination of wave impact and over-wash, so a long duration of the storm is necessary to coincide with high tide. An empirical Intensity-Duration threshold has also been obtained with the following function I = 248.7 D−0.45. Damage can occur with moderate storms, but with severe effects only with exceptional wave and sea-level values, during long-lasting storms.

Effect of Climate Change on Agricultural Productivity in Japan

The study sought to examine the effect of climate change on agricultural productivity in Japan. The study adopted the cross-section research design. Questionnaires were used to collect the data. The respondents included farmers and officials in Japan's Ministry of Agriculture, Forestry and Fisheries. The study indicated the negative and significant correlation between agricultural productivity and climate change. Climate change was found to be satisfactory in explaining agricultural productivity in Japan. The results indicated that climate change is a good predictor of agricultural productivity. The regression results showed that climate change is negatively and significantly related to agricultural productivity. The results implied that when the climate change deteriorates by one unit, the agricultural productivity will reduce by 0.327 units holding other factors constant. The effect of climate change is frequent wildfires, more extended periods of drought in some regions and an increase in the number, duration and intensity of tropical storms. The study recommended there is a need to focus on planet-friendly investments. Individuals can spur change through savings and investments by choosing financial institutions that do not invest in carbon-polluting industries. The government needs to accomplish sensitization program awareness on cause, influence, reduction and adjustment to environmental change. The government needs to additionally urge the adoption of smart agriculture where farmers do not count on rain feed agriculture but on scientific agriculture. It should provide farmers with drought-resistant seeds and livestock to improve production and ensure food security in Japan. Technological development can decrease the unfavorable effects of weather irregularity and might affect global adaptation efforts favoring various nations. There should be an emphasis on more tree planting in the country. Keywords:&nbsp; Climate Change, Agricultural Productivity, Japan

Sediment sorting and bedding dynamics of tidal flat wetlands: Modeling the signature of storms

Field studies suggest that storms can considerably affect the morphology, sedimentology and bedding structure of tidal flat wetlands because of their high-energy, while numerical modeling studies unravelling the underlying mechanisms remain rare. With a tidal flat of the Changjiang Delta, China as a reference site, this study explores the role of storms on sediment sorting and bedding behaviors using a biomorphodynamic model that couples hydrodynamics, sediment transport, marsh dynamics and morphological change. Model results indicate that storms can leave clear signatures on tidal flats in both horizontal and vertical sedimentary features, in agreement with field observations. The high bed shear stress induced by storms can initiate the motion of relatively coarse sediment which can be brought shoreward during the flood and settle on the upper tidal flats (or saltmarshes), altering the typically observed cross-shore “landward fining” phenomenon. The storm-entrained coarse sediment on the higher flat is usually hard to be brought offshore during calm weather, and hence leaving an evident sand-dominated layer (SDL) within neighboring mud-dominated layers (MDL). Storms can also destroy tidal rhythmites formed under calm weather. With the increase in storm intensity and duration, the thickness and the sand fraction of the SDL increase accordingly. The SDL thickness generated by a weaker storm during the spring tide is larger than that of a stronger storm during the neap tide. Storm chronology also plays an important role. In particular, the impact of two overlapping or temporally close storms is larger than the sum of the two individual storms. Overall, this study results in a more in-depth mechanistic understanding of storm impacts on tidal flat biomorphodynamics, providing a scientific facet to make sustainable management strategies for coastal wetlands.

Microbially induced sedimentary structures (MISS) generated by episodic storm surges in a temperate coast

This study recognizes the creation of primary sedimentary structures in a modern environment that reports valuable insights into the role of microbiota in sculpting sedimentary structures, and it may explain many previously confusing sedimentary structures in the rock record. The research considered the frequent flooding events on a coastal sedimentary flat colonized by microbial mats and the effect produced by severe storm surge events. Large-scale microbially induced sedimentary structures (MISS) were created; thus, the interaction between meteorologic, oceanographic, and geomorphologic conditions necessary to form them was analysed. The study was developed in Paso Seco, Argentina (40°38′31” S - 62°12′54” W), a sedimentary flat behind a sand spit, coated by thick microbial mats recurrently affected by storm events. Water level measurements were recorded continuously for five years (measurement interval 10 min). The seawater inundations were related to synoptic weather maps and oceanographic parameters (wave height, period, and tides) to analyse the cause of storm surges. Two situations of severe storms were studied in 2018 and 2019. The inundation of the study area occurs when a cold front in association with a low-pressure centre in the Atlantic Ocean, moving in an SW-NE direction, produces strong SW winds higher than 45 km h−1 and wave height higher than 2 m. Strong winds and storm duration (two or three days) in co-occurrence with spring tides create an extreme erosional event that affects the sedimentary microbial flat. In sum, the interaction between storm surge, high tide, wave setups and wave heights in Paso Seco produces coastal hinterland flooding that creates meter-sized MISS such as roll-ups, erosional pockets, and remnants mats structures. The impact of storm surges on the coast is common and catastrophic in modern times but is challenging to identify in the sedimentary record. Therefore, the microbial structures presented here could help interpret high-energy events occurrence, favourable to assessing past environmental conditions.

Flood Analysis and Non-Structural Approach for Flood Protection in Sg. Kelantan

Flooding is categorized as a natural disaster that occurs due to various climatic and geophysical factors. Malaysia is a lucky country as it experiences a tropical climate and generally protected from extreme drought. However, the states located along the east coast of the Peninsular Malaysia such as Kelantan, Terengganu, and Pahang always experienced a heavy flood, especially during the monsoon season due to high intensity of rainfall. The objectives of this paper were to simulate Flood Hydrographs for Various Storm Duration by using Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS), to investigate the location of floodplain at the catchment area of Sg. Kelantan by using River Analysis System (HEC-RAS), to identify the non-structural approach that can reduce the rate of flood based on its topography. By using HEC-HMS and HEC-RAS software, the peak discharge from each rainfall stations for different average recurrence interval (ARI) were calculated. Various non-strctural measures to reduce the impacts of flood are discussed.

Physiographic Controls on Landfast Ice Variability from 20 Years of Maximum Extents across the Northwest Canadian Arctic

Landfast ice is a defining feature among Arctic coasts, providing a critical transport route for communities and exerting control over the exposure of Arctic coasts to marine erosion processes. Despite its significance, there remains a paucity of data on the spatial variability of landfast ice and limited understanding of the environmental processes’ controls since the beginning of the 21st century. We present a new high spatiotemporal record (2000–2019) across the Northwest Canadian Arctic, using MODIS Terra satellite imagery to determine maximum landfast ice extent (MLIE) at the start of each melt season. Average MLIE across the Northwest Canadian Arctic declined by 73% in a direct comparison between the first and last year of the study period, but this was highly variable across regional to community scales, ranging from 14% around North Banks Island to 81% in the Amundsen Gulf. The variability was largely a reflection of 5–8-year cycles between landfast ice rich and poor periods with no discernible trend in MLIE. Interannual variability over the 20-year record of MLIE extent was more constrained across open, relatively uniform, and shallower sloping coastlines such as West Banks Island, in contrast with a more varied pattern across the numerous bays, headlands, and straits enclosed within the deep Amundsen Gulf. Static physiographic controls (namely, topography and bathymetry) were found to influence MLIE change across regional sites, but no association was found with dynamic environmental controls (storm duration, mean air temperature, and freezing and thawing degree day occurrence). For example, despite an exponential increase in storm duration from 2014 to 2019 (from 30 h to 140 h or a 350% increase) across the Mackenzie Delta, MLIE extents remained relatively consistent. Mean air temperatures and freezing and thawing degree day occurrences (over 1, 3, and 12-month periods) also reflected progressive northwards warming influences over the last two decades, but none showed a statistically significant relationship with MLIE interannual variability. These results indicate inferences of landfast ice variations commonly taken from wider sea ice trends may misrepresent more complex and variable sensitivity to process controls. The influences of different physiographic coastal settings need to be considered at process level scales to adequately account for community impacts and decision making or coastal erosion exposure.

Impacts of Hurricane Matthew on adjacent developed and undeveloped barrier islands in southeastern North Carolina

High-magnitude storms such as hurricanes can cause significant and potentially long-lasting morphological coastal change, particularly along low-lying barrier islands. This study investigated the impacts of Hurricane Matthew (2016) on neighboring undeveloped Masonboro Island reserve and engineered/nourished Wrightsville Beach barrier islands, located in southeast North Carolina. Using a combination of high-resolution pre- and post-storm RTK–GPS beach surveys, coupled with direct observations, storm surge and wave runup calculations and aerial imagery, a range of contrasting storm-induced coastal changes and impact regimes were identified across the two adjacent barriers. Storm impacts were especially pronounced across low-lying undeveloped central/southern Masonboro Island, which was dominated by significant overwash processes, leading to landward directed barrier crest migration. In contrast, only short-lived and minor collision with the dune base was observed at Wrightsville Beach, were storm impacts were dominated by a swash storm regime resulting in significant beach erosion. Field- and aerial based observations match well with modeled extreme water level estimates. This study offers a real-time example of how geomorphologically different neighboring islands respond to specific storm events, and how storm impact regime type and duration helps explain differences in barrier responses. Similar storm impacts are likely at other locations with comparable barrier island settings and differing coastal management approaches.

Increasing trends in rainfall erosivity in the Yellow River basin from 1971 to 2020

Hourly precipitation data from 1971 to 2020, collected from 98 stations distributed across the Yellow River basin, were analyzed to detect changes in characteristics on rainfall and rainfall erosivity for all storms and storms with extreme erosivity (greater than 90th percentile). Results showed that over the past 50 years, rainfall erosivity at both event and seasonal scales over the whole basin increased significantly (p < 0.05) with rates of 5.46% and 6.86% decade-1, respectively, compared to the 1981–2010 average values. Approximate 80% of 98 stations showed increasing trends and 20% of stations had statistically significant trends (p < 0.1). The increase of rainfall erosivity resulted from the significant increasing trends of average storm precipitation (p < 0.1), duration (p < 0.1), rainfall energy (p < 0.05) and maximum 1-h intensity (p < 0.05). In addition, the total extreme erosivity showed significant upward trends at a relative rate of 6.05% decade-1 (p < 0.05). Extreme erosivity storms occurred more frequently and with higher rainfall energy during the study period (p < 0.05). Trends for seasonal total and extreme erosivity were also estimated based on daily rainfall data, and the changing magnitudes were similar to those based on hourly rainfall data, which suggested daily rainfall can be applied to detect interannual and long-term variations of rainfall erosivity in the absence of rainfall data with higher resolution. It was suggested that soil and water conservation strategies and vegetation projects conducted within the Yellow River basin should be continued and enhanced in the future.

Automating rainfall recording: Ensuring homogeneity when instruments change

Sub-daily rainfall is used in modelling of small catchments, design of urban drainage, calculating soil erosion, understanding the water balance of vegetated catchments, and assessing the impact of climate change on short duration storms. Hence it is critical to ensure that sub-daily rainfall records are homogeneous, but with a global shift to automated measurement of rainfall, there has been a change in the rainfall recording instrumentation. Although changes in instrumentation should be documented, in many cases this is not the case and station metadata are missing. As result, studies of rainfall patterns, particularly those investigating trends, often cannot report their treatment of possible inhomogeneities and must assume the data is suitable for further analysis.Here, we argue that standard quality assurance methods for checking inhomogeneities in rainfall may not identify a change in the rainfall record due to a change in instrumentation. Through testing (1) an aggregation of rainfall to the coarsest instrument resolution, (2) removal of rainfall below a minimum rainfall depth, (3) removal of rainfall below a minimum accumulation (event) depth, and (4) a combination of the above adjustments, we present recommendations for ensuring sub-daily rainfall is homogenous with minimum alteration to the rainfall record.We assess the proposed methods using the case study of Australia’s sub-daily rainfall monitoring network, where, in 1996 the pluviograph network was switched to tipping buckets, creating a large-sample test bed with a known systematic instrumentation change. Our results show that event-based statistics are considerably more sensitive to instrument change than annually aggregated rainfall statistics and hence standard methods for quality assurance may not identify possible inhomogeneities. We suggest an aggregation of the data to the coarsest instrument resolution, with the removal of small rainfall accumulations, can alleviate inhomogeneities for event-based statistics, whereas, for annual statistics, aggregation to the coarsest instrument resolution is sufficient. In the absence of a known instrumentation change, removing rainfall at or below the instrument resolution is also a viable technique for improving rainfall record homogeneity for event-based statistics. These findings will aid future sub-daily rainfall studies by justifying the use of a minimum rainfall or event depth for subsequent analysis.

Evaluation of an urban drainage system using functional and structural resilience approach

ABSTRACT This study presents a resilience-based evaluation of an urban drainage system (UDS) under the impact of functional and structural failure modes. Resilience based analysis is carried out using SWMM for a part of Gurugram City of Haryana, India. For simulating the drainage system response, half-hourly rainfall data available from GPM-IMERG was utilized to estimate the design storm of suitable duration. Sensitivity analysis is carried out to overcome the problem of lack of in-depth data to perform model calibration and validation. Besides, a comparison of three different estimation approaches of subcatchment width, an important SWMM parameter, is also presented. Different rainfall and urban growth scenarios were considered to analyse the drainage system's functional and structural resilience. For the studied UDS, a total of 22 vulnerable nodes were identified through the structural resilience approach, and the functional resilience approach revealed that urbanization has more pronounced effects on UDS than climate change.

Investigation of the Effect of Climate Change on Extreme Precipitation: Capital Ankara Case

This study examines the potential impacts of climate change on extreme precipitation. Rainfall analysis with stationary and nonstationary approach for observed and future conditions is performed for (1950-2015 period) observed data of 5, 10, 15, 30 minutes and 1, 2, 3, 6 hour and projections (2015-2098 period) of 10, 15 minutes and 1, 6 hour for Ankara province, Turkey. Daily projections are disaggregated to finer scales, 5 minutes storm durations, then five minutes time series aggregated to the storm durations that are subject of interest. Nonstationary Generalized Extreme Value (GEV) models and stationary GEV models for observed and future data are obtained. Nonstationary model results are in general exhibited smaller return level values with respect to stationary model results of each storm duration for observed data driven model results. Considering the projected data driven model results; on average nonstationary models produce mostly lower return levels for mid and longer return periods for all storm durations and return periods except one hour storm duration. Depending on the models and Representative Concentration Pathways (RCP), there are different results for the future extreme rainfall input; yet all results indicate a decreasing extreme trend.