Return Period Research Articles

Stormwater controls for channel stability: Focusing on bed material transport prevents degradation.

The hydrologic benefits of catchment-scale implementation of stormwater control measures (SCMs) in mitigating the adverse effects of urbanization are well established. Nevertheless, recent studies indicate that the Unified Stormwater Sizing Criteria (USSC) regulations, mandating the combined use of distributed and storage stormwater controls, do not protect channel stability, despite their effectiveness in reducing runoff from impervious surfaces. The USSC are the basis of SCM design in 11 U.S. states and the District of Columbia. This study employed a calibrated, sequential modeling approach, which integrated a catchment-scale Storm Water Management Model (SWMM) with the Hydrologic Engineering Center River Analysis System (HEC-RAS), to evaluate the effectiveness of two alternative stormwater regulations in preventing channel erosion. A three-step methodology was developed using the calibrated SWMM and HEC-RAS models: (1) establish the pre-development scenario; (2) design SCMs for channel stability under design storm conditions; and, (3) assess regulation effectiveness through continuous simulations. The modeling results revealed that designing stormwater controls using the USSC increased sediment transport for the 1-, 2-, and 5-yr, 24-hr annual recurrence interval (ARI) design storms 2 to 2.7 times the pre-development conditions. SCM designs aimed at matching the sediment transport of the pre-development catchment reduced peak flows 30-70% and prevented knickpoint formation, as compared to designs based on hydrologic targets only. Study results demonstrate that to protect channels from degradation following urban development, the morphology and bed material of the receiving channel must be considered in the design of stormwater controls.

Investigating the spillover effect of implied volatility on nifty return in different time periods with reference to index options: a multivariate GARCH approach

Investigating the spillover effect of implied volatility on nifty return in different time periods with reference to index options: a multivariate GARCH approach

The Impact of River Mouth Sediment Deposition on Flood Risk: The Case Study of The Sakarya River

Flooding is a natural disaster that causes loss of life and property worldwide. Floods can be predicted and their damages can be reduced. Various natural and man-made factors can cause floods. Sediment movement can be counted as one of the causes of floods, albeit rarely. The Sakarya River bed and river mouth is one of the risky areas for flooding due to sediment deposition. Due to the activities of quarries on the Sakarya River, the amount of sediment carried by the river increases, and the damage to the river bed morphology. In rare cases, the mouth of the river is completely closed due to sedimentation, which has caused many disasters such as coastal flooding and capsizing of marine vessels, leading to loss of life and property. Therefore, the occurrence of floods due to sediment deposition at the mouth of Sakarya River was investigated. The 5, 10, 25, 50, 100, and 500-year return period flows in the downstream part of the Sakarya River and Karasu district were analyzed with the 2D flood model in case of insufficient discharge from the river mouth. Water depth, velocity, and flood hazard maps for these return periods were prepared. The impact of flooding on Karasu district was analyzed in terms of affected buildings and affected area (ha). Thus, the effects of the floods occurring in the downstream region as a result of the interventions to the river bed in the upstream region were analyzed.

Aseismic slip history after the 2011 Tohoku earthquake in the Suruga Trough, Central Japan

Summary Detailed investigations of aseismic slow slip events (SSEs) are crucial for estimating the strain budget and SSE mechanisms within subduction zones. The Suruga Trough, which includes the Tokai seismic gap, is an important area in Japan from a hazardous perspective. However, the aseismic slip history of this trough following the 2011 Tohoku earthquake is difficult to determine as a result of post-seismic deformation caused by the earthquake. In this study, we provided detailed imaging of the interplate aseismic slip in the Suruga Trough after the 2011 Tohoku Earthquake by applying a network inversion filter to global navigation satellite system data and considering viscoelastic deformation and afterslip caused by the earthquake. The analysis revealed the 2012 Shima long-term SSE (l-SSE), 2013-2016 Tokai l-SSE, 2017-2020 Shima l-SSE, and 2023-2024 Atsumi+Tokai l-SSE, with the slip area expanding to the area adjacent to the Tokai seismic gap from July 2023, consequently changing the stress state to promote the anticipated Tokai earthquake. The findings of this study suggest that the recurrence interval of the Tokai slow slip ranges from 10 to 13 years, with a duration of approximately 4-5 years and a total magnitude ranging from 6.5 to 7.1. The l-SSE zone shows that the upper-limit temperature threshold, which is the temperature at the upper bound of the l-SSE zone aligning the 350°C isothermal line in the Tokai segment, does not hold in the Suruga Trough. The change in strike direction of the l-SSE zone suggests that a discontinuous factor controls the l-SSE occurrence, such as high pore pressure caused by fluid infiltration to the plate interface. Furthermore, we explored a gap between the short-term SSE (s-SSE) and l-SSE zones, and the findings indicated a non-continuous transition from l-SSE to s-SSE, thus providing insights into the discontinuous factors that regulate l-SSE and s-SSE generation. The recurrence interval (10–13 years) and duration (4-5 years) of the Tokai SSEs are long, and their moment rates (1015.8Nm/day) are low compared to those of the l-SSEs in other regions. The SSE parameters suggest that the scaling law may not apply to SSEs in the Suruga-Nankai Trough with the prolonged duration.

Tracing the relationship between the upper plate earthquake cycle and megathrust slip, the Atacama fault system in Northern Chile

Inland-normal faulting is recognised as an important process following large subduction earthquakes. The lack of data limits the understanding of how normal fault reactivation relates to the subduction earthquake cycle. We characterised the palaeoseismology of the Atacama fault system (AFS) in the Chilean subduction zone. Our results showed that upper plate normal faulting earthquakes with Mw 7.0 and recurrence intervals of 35 ± 9 ky generated surface ruptures preserved as fault scarps. The average fault slip rate of 0.07 ± 0.01 m/kyr is three orders of magnitude slower than the convergence velocity, and the recurrence intervals of surface-rupturing earthquakes on the studied faults are much larger than the recurrence of great to giant (Mw > 8.5) subduction earthquakes in the Chilean margin. This demonstrates that the reactivation of an individual fault in the AFS is not always synchronised with this type of subduction earthquake.

ANALISIS DEBIT RANCANGAN MENGGUNAKAN METODE HASPERS PADA DAS BABAK KABUPATEN LOMBOK TENGAH

The Babak River Watershed is located in Tanah Beak Village and borders directly with Bagu Village, Pringgarata District, Central Lombok Regency, which is one of the areas where river flooding and drainage systems often occur. In the analysis, the method used is to collect rainfall data and river watershed (DAS) data, the data is analyzed using the Normal method, Normal log, Person Type III log and Gumbel method, then calculate the design discharge PMP value, after the calculation is carried out, the discharge is obtained. design in the Babak river basin using the Haspers method for each 2 year return period the discharge is = 55966.851 m3/sec, 5 year return period the discharge is = 58655.999 m3/sec, 10 year return period the discharge is = 60437 .904 m3/sec, 20 year return period debit of = 62125.576 m3/sec, 25 year return period debit of = 62687.966 m3/sec, 50 year return period debit of = 64356.591 m3/sec, return period 100 years of discharge is = 66027.221 m3/sec. Meanwhile, the maximum rainfall value that may occur, the PMP value is obtained = 967.256 mm.

Treatment, prognosis, and outcome of dogs treated for rectal plasmacytoma: a multicentric retrospective study.

The aim of this study was to report the outcome and prognosis of canine patients treated medically or surgically for rectal plasmacytomas and to identify factors associated with recurrence, mortality, or progression to multiple myeloma. The databases of 7 referral hospitals were reviewed. The Kaplan-Meier method and Cox proportional hazards analysis were used to determine the association of a range of variables with recurrence and progression-free interval for the surgically treated patients. 20 dogs were included. Nineteen cases were treated surgically, and 1 case was treated conservatively (analgesia and monitoring). Metastatic lesions were detected in 2 of 20 dogs (10%). Four of 19 dogs (21%) treated surgically developed postoperative complications, 1 major (1 of 19 [5.2%]) and 3 minor (3 of 19 [15.8%]). Tumor recurrence was identified in 6 of 19 dogs (31.5%). The 1-, 2-, and 3-year survival rates were 95%, 72%, and 66%, respectively. None of the variables tested were associated with occurrence of complications. Increased distance from the anus, incomplete surgical margins, and decreasing surgeon experience were associated with an increased risk of recurrence. No progression to multiple myeloma was seen in any of the cases. Surgical treatment of rectal plasmacytomas is associated with a low major complication rate and long survival. Metastasis and recurrence rates are significantly higher than previously reported. Conservative surgery leads to long-term survival, but recurrence is common. Future studies should focus on the benefits of adjuvant treatments.

Descriptive Methodology for Risk Situation of Disastrous Sea Waves in the China Sea

To meet the needs of marine disaster prevention and mitigation, this paper proposes a systematic methodological framework to describe the annual risk situation of Disastrous Sea Waves (DSWs) from four perspectives. Its application is demonstrated for the China Sea in 2023 as a case study. The systematic approach is reflected in the following: (1) a comprehensive description of DSW risks based on three dimensions: occurrence frequency, maximum intensity, and hazard index; (2) an overview of the DSW risk characteristics for the year through spatial and monthly distributions; (3) a comparative analysis of the year’s DSWs, with historical data based on anomalies and return periods used to assess the risk characteristics and extremities; and (4) an analysis of the causes of the year’s characteristics based on monthly anomalies and weather systems. Through its application to the China Sea in 2023, the analysis process is introduced as follows. (1) High-Frequency and Intensity Areas: DSWs frequently occurred in the northeastern South China Sea (SCS) and Taiwan Strait, exceeding 450 h. The maximum significant wave height (Hs), reaching 11.3 m, was recorded in the southern East China Sea (ECS) in August. (2) Extremity in Frequency and Attribution: The occurrence frequency was extremely high, with the cumulative hours exceeding the historical average by 159 h (9.1%). The southwestern SCS showed the most significant excess, up to 168 h (>120%). The reason for this was that DSWs in January caused by prolonged cold air lasted 236 h longer (121%). (3) Extremity in Intensity and Attribution: The maximum Hs in the southern ECS and Taiwan Strait was 2 m (30%) higher than the historical average. The intensified cold air waves caused the higher intensities. (4) Hazard Levels: Higher risk occurred in the southwestern SCS, southern ECS, and Taiwan Strait, while the highest extremity occurred in the Bohai Sea.

Modeling the Inter-Arrival Time Between Severe Storms in the United States Using Finite Mixtures

When inter-arrival times between events follow an exponential distribution, this implies a Poisson frequency of events, as both models assume events occur independently and at a constant average rate. However, these assumptions are often violated in real-insurance applications. When the rate at which events occur changes over time, the exponential distribution becomes unsuitable. In this paper, we study the distribution of inter-arrival times of severe storms, which exhibit substantial variability, violating the assumption of a constant average rate. A new approach is proposed for modeling severe storm recurrence patterns using a finite mixture of log-normal distributions. This approach effectively captures both frequent, closely spaced storm events and extended quiet periods, addressing the inherent variability in inter-event durations. Parameter estimation is performed using the Expectation–Maximization algorithm, with model selection validated via the Bayesian information criterion (BIC). To complement the parametric approach, Kaplan–Meier survival analysis was employed to provide non-parametric insights into storm-free intervals. Additionally, a simulation-based framework estimates storm recurrence probabilities and assesses financial risks through probable maximum loss (PML) calculations. The proposed methodology is applied to the Billion-Dollar Weather and Climate Disasters dataset, compiled by the U.S. National Oceanic and Atmospheric Administration (NOAA). The results demonstrate the model’s effectiveness in predicting severe storm recurrence intervals, offering valuable tools for managing risk in the property and casualty insurance industry.

Effectiveness and cytokine profile of combined anti-vascular endothelial growth factor and corticosteroid therapy for chronic retinal vein occlusion.

To investigate whether sub-Tenon injection of triamcinolone acetonide (STTA) combined with anti-vascular endothelial growth factor (VEGF) prolongs the recurrence intervals of macular edema (ME) for chronic retinal vein occlusion (RVO) and to investigate the differences in intraocular inflammatory cytokines between good responders (GRs) and non-responders (NRs). This retrospective, observational study involved 42 eyes of 42 patients with ME due to chronic RVO who had received only anti-VEGF for ≥ 1 year and were transitioned to combination therapy. GRs were defined as patients whose recurrence intervals were prolonged by ≥ 2 weeks compared with patients receiving anti-VEGF alone. Moreover, immediately before starting the combined therapy, aqueous humor was collected and the following inflammatory cytokines were compared between GRs and NRs: CCL11, MCP-3, IP-10, CCL13, G-CSF, GM-CSF, IL-1α, IL-15, IL-4, M-CSF, MMP-9, TNF-α, MCP-1, CXCL-1, CXCL12, IL-8, galectin-1, IFN-γ, IL-12, IL-2, IL-6, MMP-1, PDGF-AA, and VEGF-A. These results were analyzed by nominal logistic regression after stepwise variable selection. There were 26 eyes (62%) in the GR group. Nominal logistic analyses showed that a higher concentration of IL-1α (P = 0.016) and lower concentrations of IL-5 (P = 0.015), IL-6 (P = 0.022), and galectin-1 (P = 0.015) were significantly associated with the extension of the time from injection to recurrence of ME. Combined anti-VEGF and STTA therapy for chronic RVO was effective in 62% of patients, suggesting the effectiveness of STTA. Higher IL-1α and lower IL-5, IL-6, and galectin-1 were the factors associated with combined treatment effectiveness.

Comprehensive benefits evaluation of low impact development using scenario analysis and fuzzy decision approach

The comprehensive benefit evaluation of LID based on multi-criteria decision-making methods faces technical issues such as the uncertainties and vagueness in hybrid information sources, which can affect the overall evaluation results and ranking of alternatives. This study introduces a multi-indicator fuzzy comprehensive benefit evaluation approach for the selection of LID measures, aiming to provide a robust and holistic framework for evaluating their benefits at the community level. The proposed methodology integrates quantitative environmental and economic indicators with qualitative social benefit indicators, combining the use of the Storm Water Management Model (SWMM) and ArcGIS for scenario-based analysis, and the use of hesitant fuzzy language sets and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) for decision-making. The framework’s novelty lies in the integration of the hesitant fuzzy weighted average algorithm to handle subjective uncertainties in expert judgment and the incorporation of multi-return period scenarios to enhance the robustness of the evaluation. The comprehensive benefits of 26 LID configurations were conducted in Chenglong Road Subdistrict under five rainfall return period scenarios of 5, 10, 20, 50, and 100 years. The results show that LID measures, particularly combinations of sunken green spaces and permeable paving, offer significant reductions in runoff and peak flow, along with improved flood mitigation across multiple return periods. Additionally, this study identifies practical LID implementation priorities for local decision-makers. The relative closeness is influenced by the indicators and non-calibrated parameters. However, it overall does not affect the main trends and key insights derived. The robustness of the proposed approach is reinforced by four key aspects: the impact of the Thiessen polygon method in ArcGIS, the influence of composite runoff coefficient and iterative optimization in SWMM, the effect of hesitant fuzzy linguistic sets and TOPSIS on weight calculation, and the contribution of simulations under different return periods to stability analysis.

Safety of topical estrogen therapy during adjuvant endocrine treatment among patients with breast cancer: A meta-analysis based expert panel discussion.

Endocrine treatments, such as Tamoxifen (TAM) and/or Aromatase inhibitors (AI), are the adjuvant therapy of choice for hormone-receptor positive breast cancer. These agents are associated with menopausal symptoms, adversely affecting drug compliance. Topical estrogen (TE) has been proposed for symptom management, given its' local application and presumed reduced bioavailability, however its oncological safety remains uncertain. The present systematic review, meta-analysis and expert panel review aimed to evaluate the strength of the available evidence on the risk of recurrence and mortality when TE is utilised in congruence with TAM or AI treatment, among BC survivors. Six databases and two prospective registers, were interrogated from inception to January 3rd, 2024. Search terms were Breast cancer AND Hormone replacement therapy AND topical/vaginal oestrogen AND recurrence/mortality. All study designs reporting the use vs. non-use of TE in breast cancer survivors receiving adjuvant endocrine treatment were included. Six observational studies were deemed eligible for inclusion. Sources of heterogeneity were explored using subgroup analysis by risk of bias, median follow-up period, node positivity and menopausal status. Trial sequential analysis was performed to quantify outcome reliability. A global expert panel was called to deliberate on the data, pinpoint areas of limited understanding, and determine the most important areas for future research. Risk ratio effect sizes (RR) and corresponding 95% Confidence Intervals (CI) of breast cancer recurrence and mortality in survivors on endocrine treatment (TAM and/or AI) exposed to TE were reported. Expert panel appraisal of meta-analysis evidence with definition of current knowledge gaps and future research aims. In 38 050 female patients receiving adjuvant endocrine treatment, of whom 1805 had been exposed to TE, TE exposure of those on AI, did not increase all-cause mortality (RR 0.99 [95%CI 0.58, 1.69], I2=81%, P = 0.96; moderate GRADE certainty). However, such exposure may convey an increased risk of recurrence (RR 2.51 [95% CI 1.10, 5.72], I2=9%, P = 0.03; low-GRADE certainty). Exposure to TE during TAM did not increase either recurrence risk or all-cause mortality. Clinical factors such as lymph node positivity at the time of diagnosis and menopausal status and follow-up time appeared to be significant confounders. The use of TE does not appear to increase either recurrence or mortality risk among BC survivors treated with TAM. An increased recurrence risk, without an increase in mortality, cannot be ruled out when TE is used during AI.

Resolving the mass transfer in the symbiotic recurrent nova T Coronæ Borealis

T Coronæ Borealis (T CrB) is a symbiotic recurrent nova with an 80-year recurrence interval whose next eruption is imminent. We aim to resolve the accretion mechanism of the binary system governing the mass transfer during its super-active phase. Using phase-resolved high-resolution spectroscopy, we analyzed the zoo of spectral-line profiles arising from the symbiotic activity. We performed Doppler tomography of selected emission lines to resolve the system's gaseous components and their different velocity regimes. We find evidence of enhanced accretion through Roche lobe overflow during the super-active phase, as traced by the oxygen, helium, and hydrogen lines. The accretion disk is found to be fully viscously evolved and extends up to its maximal radius. By mapping the kinematics of lines probing different excitation energies, we can identify distinct interaction sites. These include the bright spot at the stream impact on the accretion disk outer radius, the irradiation at the red-giant facing side, the stream-disk overflow, the accretion disk wind, and an expanding nebula. The nebula emerged at the rise of the super-active phase and underwent an acceleration phase of about five years. The temporal evolution of the lines supports the scenario where the departure from quiescence started in the disk, likely triggered by a disk instability similar to what occurs in dwarf novae outburst, leading to an increased mass accretion and causing important irradiation of the giant that has further enhanced the mass-transfer rate during the super-active phase. Symbiotic recurrent nova, such as T CrB, are governed by similar mass-transfer mechanisms as found in cataclysmic variables despite their different orbital properties (longer orbital periods imposing larger accretion disks) and evolutionary pathways.

Analysis and Flood Mapping of Pekalen Watershed of Probolinggo Regency Using HEC-RAS Application

Flooding is one of the natural disasters that needs attention, especially in the Pekalen watershed, Probolinggo Regency. The purpose of this research is to analyze the design flood discharge and mapping of the area potentially affected by inundation. The research stages began with arithmetic area average rainfall analysis, log pearson type III design rainfall analysis, chi squared and smirnov-kolmogorov distribution fit test, mononobe rainfall intensity, HSS Nakayasu design flood discharge analysis, and flood mapping with HEC-RAS 2D flood modeling. The design flood discharge of Pekalen watershed at 10-year return period is 421.4 m³/s, 25-year return period is 455.12 m³/s, and 50-year return period is 479 m³/s. The areas potentially affected by inundation at 25 years return periods are Sukomulyo, Sukokerto, Pajarakankulon, Kradenan, Tanjung, Karangbong, Temenggungan, Karanggeger, Ketompen, Petemon, Selogudigwetan, Selogudigkulon, Puspan, Braniwetan, Branilor, Sumbersecang, Satreyan, Maronkidul, Gerongan, Brabe, Condong, Racek, Pesawaran, Ranugedang, Jangkang, Segaran, Ranuagung, Tiris, Andungsari, Andungbiru, and Sumberaren.

Analisis Finansial Usahatani Nilam di Kecamatan Pasaman Kabupaten Pasaman Barat

Patchouli oil is a potential Indonesian essential oil that is widely traded in the world market. This study aims to analyze patchouli farming financially using the B/C Ratio, Net Present Value, Internal Rate of Return and Payback Period at an interest rate of 9% in patchouli farming in Pasaman District. The method used in this study is a survey. The data analysis used in this study is quantitative descriptive, aimed at determining the financial feasibility of patchouli farming using investment criteria in the form of B/C Ratio, Net Present Value, Internal Rate of Return and Payback Period. From the investment criteria study, it was found that patchouli farming is feasible to be implemented, with a B/C Ratio value of 1.09. The NPV value is IDR 16,524,016.00, -. The IRR value is 97.00%. The Payback Period value is 5 years 10 months 7 days.

Estimating the impact of 2D urban landscape patterns on extreme precipitation based on non-stationary models in the Guangdong-Hong Kong-Macao Greater Bay Area, China.

Rapid urbanization has significantly altered surface landscape configurations, leading to complex urban climates. While much attention has been focused on impervious surfaces' impact on extreme precipitation, a critical gap remains in understanding how various 2D urban landscape components influence extreme precipitation across different durations. Through an analysis of the non-stationarity and spatiotemporal variations in extreme precipitation across the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 1990 to 2020, we constructed the non-stationary Generalized Additive Models for Location Scale and Shape (GAMLSS) model by introducing six urban landscape structural metrics as explanatory variables for each of the 27 meteorological stations in the GBA. Additionally. we assessed the frequency of these metrics in the best-fitting models and predicted design values across different interannual periods. Our findings reveal that aggregation metrics (patch density: PD) and diversity metrics (Shannon's Diversity Index: SHDI) appeared more frequently in the best-fitting models than other metrics within all extreme precipitation indices. For short-duration extreme precipitation indices (≤ 3h), the area matrix (Impervious Surface Percentage: ISP), PD, and SHDI were selected more often than other metrics, whereas for long-duration (> 3h), PD and SHDI had a higher relative frequency as ISP's impact decreased. Design values peaked in the 2010s across all return periods (100, 50, and 20years), highlighting the importance of integrating urban landscape features into non-stationary models of extreme precipitation. This research provides valuable insights for improving the management of urbanization-induced heavy precipitation and flood risks.

Changes in event soil moisture-temperature coupling can intensify very extreme heat beyond expectations

The most disastrous heatwaves are very extreme events with return periods of hundreds of years, but traditionally, climate research has focussed on moderate extreme events occurring every couple of years or even several times within a year. Here, we use three Earth System Model large ensembles to assess whether very extreme heat events respond differently to global warming than moderate extreme events. We find that the warming signal of very extreme heat can be amplified or dampened substantially compared to moderate extremes. This modulation is detectable already in mid-century projections. In the mid-latitudes, it can be explained by changes in event soil moisture-temperature coupling during the hottest day of the year. The changes depend on the interplay of present soil moisture and coupling during heat events as well as projected precipitation changes. This mechanism is robust across models, albeit with large spatial uncertainties. Our findings are highly relevant for climate risk assessments and adaptation planning.

PELAPORAN SPT MASA PPH 21 WAJIB PAJAK ORANG PRIBADI DENGAN MENGGUNAKAN E-BUPOT PADA KANTOR KONSULTAN PAJAK EXCELLENT EAGLESWAN: SKEMA PENGENAAN TARIF EFEKTIF RATA-RATA (TER)

The change in the calculation scheme & the deduction of PPh 21 rates for individual taxpayers and the change in reporting procedures for the periodic tax return electronically require taxpayers to adapt to these changes. The objective of this study is to assist taxpayers in understanding the effective tax rate and reporting procedures using e-Bupot so that taxpayers are not confused about the procedures that have been determined. This research uses a qualitative method by observing client salary data. Data regarding client salaries were obtained from observations conducted at the Excellent Eagleswan, Tax Consultant Office. In addition, we also conducted simulations using the online DJP website through e-Bupot. E-Bupot is used to make it easier for taxpayers to report Periodic Tax Return PPh 21 which is more effective and efficient than the use of e-SPT. This research is crucial because there is a new deduction system for PPh 21 and a new procedure for reporting periodic tax return, so taxpayers can find this information to facilitate them in the process.

Generalised Additive Model-Based Regional Flood Frequency Analysis: Parameter Regression Technique Using Generalised Extreme Value Distribution

This study examines the effectiveness of Generalised Additive Models (GAMs) and log-log linear models for estimating the parameters of the generalised extreme value (GEV) distribution, which are then used to estimate flood quantiles in ungauged catchments. This is known as the parameter regression technique (PRT). Using data from 88 gauged catchments in New South Wales, Australia, flood quantiles were estimated for various annual exceedance probabilities (AEPs) of 50%, 20%, 10%, 5%, 2%, and 1%, corresponding to return periods of 2, 5, 10, 20, 50, and 100 years, denoted by Q2, Q5, Q10, Q20, Q50, and Q100, respectively. These flood quantiles were then used as dependent variables, while several catchment characteristics served as independent variables in the regression. GAMs were employed to capture non-linearities in flood generation processes. This study evaluates different GAMs and log-log linear models, identifying the best ones based on significant predictors and various statistical metrics using a leave-one-out (LOO) validation approach. The results indicate that GAMs provide more accurate and reliable predictions of flood quantiles compared to the log-log linear models, demonstrating better performance in capturing observed values across different quantiles. The absolute median relative error percentage (REr%) ranges from 33% to 39% for the GAMs and from 36% to 45% for the log-log models. GAMs demonstrate better performance compared to the log-log linear models for quantiles Q2, Q5, Q10, Q20, and Q50; however, their performances appear to be similar for Q100.

Storylines of Unprecedented Extremes in the Southeast United States

Abstract Disaster planning based on historical events is like driving forward while only looking in the rear-view mirror. To expand our field of view, we use a large ensemble of weather simulations to characterise the current risk of extreme weather events in case study locations in the Southeastern United States. We find that extreme temperature events have become more frequent between 1981 and 2021, and heavy precipitation events are also more frequent in the wettest months. Combining a historical analysis of people’s recent experience with the rate of change of extreme events, we define four quadrants that apply to groups of case studies: Sitting Ducks”, “Recent Rarity”, “Living Memory”, and “Fading Memory”. A critical storyline is that of the “Sitting ducks”: locations where we find a high rate of increase in extreme events and where the most extreme event in recent memory (1981-2021) has a low return period in today’s climate. We find that these locations have a high potential for surprise. For example, in Montgomery County, Alabama, the most extreme temperature event since 1981 has a return period of 13 years in the climate of 2021. In these places, we offer unprecedented synthetic events from the large ensemble for use in disaster preparedness simulations to help people imagine the unprecedented. Our results not only document substantial changes in the risk of extremes in the Southeastern United States but also propose a generalizable framework for using large ensembles in disaster preparedness simulations in a changing climate.