Intensity Of Extreme Rainfall Events Research Articles

New insights into the catastrophic slope failures at Sau Mau Ping: the role of antecedent rainfall pattern

Climate change is increasing the frequency and intensity of extreme rainfall events, which aggravate the threat to the safety of natural and man-made slopes. There is growing interest in the role of rainfall characteristics in these slope failures. Most of previous studies treated the rainfall individually or as cumulative value and used hypothetical rainfall temporal patterns with no association with actual physical failures. In this study, the two deadly landslides in Sau Mau Ping, Hong Kong, in June 1972 and August 1976, which caused 165 casualties, are revisited. An intriguing question that has long been overlooked is posed: why the slopes that withstood the 1972 rainfall failed in the 1976 rainfall, given that the rainfall intensity of the latter event was only half of the former? Based on an extensive review of the forensic reports and relevant studies on the failure events, numerical modeling is carried out by a combination of seepage analysis with stability analysis and unsaturated shear strength theory. Focus is placed on the geological and hydrological settings and the rainfall characteristics, particularly the temporal pattern of the antecedent and main rainfall, to look into the causes and mechanisms for these failures. Implications of the new findings for future research and practice are also highlighted.

Characteristics and dynamic mechanism of rill erosion driven by extreme rainfall on karst plateau slopes, SW China

Driven by climate change and increased human activities, the frequency and intensity of extreme rainfall events are increasing, leading to increased risk of water erosion on slopes in karst rocky desertification (KRD) areas. However, the driving factors (rainfall intensity, slope gradient, and the degree of underground fissure pore), characteristics, and dynamic mechanisms of rill erosion on KRD slopes under extreme rainfall have received limited attention. A rainfall simulation experiment was performed to investigate the driving factors of rill erosion on KRD slopes under extreme rainfall events. The experiments were conducted using an erosion flume (4 m long, 1.5 m wide and 0.35 m deep) with five rainfall intensities (50, 105, 115, 125 and 145 mm·h−1), three-level slope gradients (5°, 15° and 25°), and three typical degrees of underground pore fissure (1 %, 3 % and 5 %). The results showed that extreme rainfall significantly stimulated the formation and development of rill erosion on KRD slopes. In particular, rainfall intensity and slope gradient significantly affected rill erosion (p < 0.05), whereas the degree of underground pore fissure did not have any distinct effect. Increasing rainfall intensity intensified rill erosion by significantly (p < 0.05) promoting the rill density, total rill surface area, and longest of rill length. With increasing slope gradient, the rill density, rill distribution density, and average rill depth significantly increased (p < 0.05). Moreover, extreme rainfall events exacerbated surface soil erosion by enhancing the hydrodynamic characteristics of slope runoff. Rill erosion was most sensitive to the shear stress of runoff, and rill density was found to be the most suitable rill index for describing surface soil erosion on the slope under extreme rainfall. The findings provide valuable insights into the characteristics and mechanisms of soil erosion in karst regions under future climate warming.

Vulnerability of wells in unconfined and confined aquifers to modern contamination from flood events

Groundwater is a primary potable water supply for coastal North Carolina (NC), but the increased intensity of extreme rainfall events and floods may exacerbate surface and subsurface processes that contribute anthropogenic chemicals to wells in the major confined aquifers of this region. We evaluated groundwater for organic chemicals of emerging concern (CEC) and the presence of tritium using flooded and not-flooded wells in the NC Department of Environmental Quality well monitoring network across the NC Coastal Plain. Flooded wells experienced standing water around the well casing at least once during the study period. Tritium concentrations, which indicate modern water presence (water recharged after 1953), were significantly greater in groundwater from flooded wells than not-flooded wells. In confined aquifers, modern water was detected at greater depths in flooded wells (206 m) than not-flooded wells (100 m). Suspect-screening high resolution mass spectrometry (HRMS) analysis of 150 groundwater samples yielded a total of 382 unique organic chemicals. Each groundwater sample contained, on average, 19 tentatively identified chemicals from the NIST 20 mass spectral database (M1) and 9 USEPA ToxCast chemicals. The number of tentatively-identified chemicals per sample was not significantly different among aquifers demonstrating the pervasive presence of the detected CECs in unconfined and confined aquifers. The presence of modern water in groundwater from flooded wells coincided with higher detection frequencies of certain organic contaminant classes, particularly pharmaceuticals, food additives, and regulated aromatic hydrocarbons. These results indicate that wells in both unconfined and confined aquifers are susceptible to modern water contamination during flood events; this finding has critical public health implications for coastal communities.

Fate of Rainfall Over the North Indian States in the 1.5 and 2°C Warming Scenarios

AbstractRise in mean temperature put a great deal of uncertainty about how weather and climate extremes may play out, particularly in India's varied climatic zones. Consequently, it is important to understand the possible changes in both magnitude and direction of weather and climate extremes like rainfall for different warming levels of 1.5 and 2°C scenarios concerning preindustrial and present levels. Hence in the present study, the precipitation behavior of seven North Indian states that is, Haryana, Himachal Pradesh, J&amp;K, Punjab, Rajasthan, Uttar Pradesh, and Uttarakhand carefully studied using CMIP5 models. Future projections of precipitation has been done for the Paris Agreement global warming level of 1.5 and 2°C scenarios. Along with model validation and future projections of precipitation, the return period of extreme rainfall is also discussed to understand the behavior of the occurrence of extreme precipitation. Statistical analysis shows that the ensemble means have the least error as compared to the other six CMIP5 models. Therefore, future analysis has been done with the ensemble mean. Our findings show that the precipitation is likely to decrease in the 1.5°C scenarios, while it is likely to increase in the 2°C scenarios. The occurrence and intensity of extreme rainfall events are likely to be more frequent in all the models. The return period of the extreme rainfall events is likely to increase in all the states in both the warming scenarios. A three‐fold rise is likely to increase extreme rainfall events in the 2°C scenario.

Impact of Short-Term Salinity and Turbidity Changes on Hatching and Survival Rates of Japanese Sea Cucumber, Apostichopus japonicus (Selenka, 1867), Eggs

The increased frequency and intensity of extreme rainfall events attributed to global climate change could lead to changes in salinity and turbidity levels in coastal waters which may negatively impact the survival of organisms, particularly during the early developmental stages. In this study, the influences of salinity and turbidity on the early life stage of Japanese sea cucumber, Apostichopus japonicus (Selenka, 1867), were studied in a series of small-scale laboratory experiments. During the first half of the experiments, A. japonicus fertilised eggs were exposed to various levels of salinity stresses (34: control, 30, 26, 22, 18, 14 PSU) for a single period of 3 h. In the second half of the experiments, following the same duration as the first experiment, fertilised eggs were exposed to different levels of turbidity, 0 (control), 100, 300, 500, and 700 NTU. The results showed that the hatching and survival rates significantly decreased as salinity dropped. As for turbidity, there were significant adverse effects on hatching and survival rates of A. japonicus. This study shows that short-term low salinity and high turbidity influenced events could potentially reduce larvae survival of A. japonicas. These factors could affect the robustness of future adult populations.

Climate Change and Rainfall Intensity–Duration–Frequency Curves: Overview of Science and Guidelines for Adaptation

AbstractOne of the most important impacts of a future warmer climate is the projected increase in the frequency and intensity of extreme rainfall events. This increasing trend in extreme rainfall i...

Estimating Rainfall Erosivity Factor Using Future Climate Projection in the Myjava Region (Slovakia)

Abstract Rainfall erosivity factor (R) of the USLE model is one of the most popular indicators of areas potentially susceptible to soil erosion. Its value is influenced by the number and intensity of extreme rainfall events. Since the regional climate models expect that the intensity of heavy rainfall events will increase in the future, the currently used R-factor values are expected to change as well. This study investigates possible changes in the values of R-factor due to climate change in the Myjava region in Slovakia that is severely affected by soil erosion. Two rain gauge stations with high-resolution 1-minute data were used to build a multiple linear regression model (r 2 = 0.98) between monthly EI 30 values and other monthly rainfall characteristics derived from low-resolution daily data. The model was used to estimate at-site R-values in 13 additional rain gauge stations homogeneously dispersed over the whole region for four periods (1981–2010, 2011–2040, 2041–2070, 2071–2100). The at-site estimates were used to create R-factor maps using a geostatistical approach. The results showed that the mean R-factor values in the region might change from 429 to as much as 520 MJ.mm.ha−1.h−1.yr−1 in the second half of the 21st century representing a 20.5% increase.

Projecting changes in extreme rainfall from three tropical cyclones using the design-rainfall approach

In the past quarter-century, Eastern North Carolina (ENC) experienced several devastating tropical cyclones that led to widespread flooding and damage. Historical climate records reflect an increasing trend in the frequency and intensity of extreme rainfall events across the eastern U.S., which is projected to continue to increase throughout the twenty-first century. Potential changes to extreme rainfall across ENC are explored and quantified for 2025–2100 for three tropical cyclones using an approach based on relative changes in future extreme rainfall frequencies (return periods) from dynamically downscaled projections. Maximum rainfall intensities at ‘2100’ could increase locally by 168%, with widespread regional increases in total rainfall up to 44%. Although these magnitudes exceed the consensus in the literature, the values here are comparable to the most extreme rainfall events observed in the U.S. during the early twenty-first century, which suggests that the intensity of projected future events is already a present-day reality.

Climate and Extreme Rainfall Events in the Mono River Basin (West Africa): Investigating Future Changes with Regional Climate Models

This study characterizes the future changes in extreme rainfall and air temperature in the Mono river basin where the main economic activity is weather dependent and local populations are highly vulnerable to natural hazards, including flood inundations. Daily precipitation and temperature from observational datasets and Regional Climate Models (RCMs) output from REMO, RegCM, HadRM3, and RCA were used to analyze climatic variations in space and time, and fit a GEV model to investigate the extreme rainfalls and their return periods. The results indicate that the realism of the simulated climate in this domain is mainly controlled by the choice of the RCMs. These RCMs projected a 1 to 1.5 °C temperature increase by 2050 while the projected trends for cumulated precipitation are null or very moderate and diverge among models. Contrasting results were obtained for the intense rainfall events, with RegCM and HadRM3 pointing to a significant increase in the intensity of extreme rainfall events. The GEV model is well suited for the prediction of heavy rainfall events although there are uncertainties beyond the 90th percentile. The annual maxima of daily precipitation will also increase by 2050 and could be of benefit to the ecosystem services and socioeconomic activities in the Mono river basin but could also be a threat.

Geographic and temporal variation in persistent pollutants in Australian humpback and snubfin dolphins

Abstract We investigated between 2014 and 2016 the concentrations of PCBs, DDTs and HCB and trace elements in blubber and skin samples of Australian humpback and snubfin dolphins collected from the Fitzroy River estuary and Port Curtis, Queensland, Australia. The concentrations of PCBs, DDTs and HCB from this study were compared with results from samples collected in 2009 and 2010 from the same areas. Our results showed that the concentrations of PCBs, DDTs and HCB have increased over time. A large proportion (~68%) of the sampled population accumulated organochlorines contaminants above thresholds over which immunosuppression and reproductive anomalies are known to occur. Results also suggest a general enrichment of some trace elements above natural levels in humpback and snubfin dolphins from the Fitzroy River estuary and Port Curtis. Extensive flooding in adjacent catchments is the most likely primary factor responsible for increased distribution and bioavailability of these contaminants into coastal waters. Land-based pollution from the adjacent catchments is an ongoing threat to coastal systems and particularly for top predators such as dolphins in the Great Barrier Reef. Climate change models predict increasing frequency and intensity of extreme rainfall events that will impact coastal Queensland and the Great Barrier Reef. Reduction of land-based persistent pollutants into coastal waters of the Great Barrier Reef will be critical for the health and survival of humpback and snubfin dolphins in this region.

The competitive advantage of C4 grasses over CAM plants under increased rainfall variability

The intensity of extreme rainfall events is increasing in many regions of the world, with important impacts on community dynamics and ecosystem functioning especially in water-limited ecosystems. The impact of the intensification of extreme precipitation on mixed communities of CAM plants and dryland C4 grasses remains poorly understood. Through a set of greenhouse experiments we investigated the effect of increasing intraseasonal rainfall variability on two separate pairs of CAM and C4 grass species (C. imbricata and B. eriopoda; O. phaeacantha and B. curtipendula) that coexist in arid grasslands across the southwest USA. The increased rainfall variability did not significantly change the biomass of C. imbricata while increasing the biomass of B. eriopoda when these two species coexisted. More extreme rainfall regimes caused a 24.8% decrease in B. curtipendula (grass) biomass, compared with a 71.3% decline in the O. phaeacantha CAM plant. Significantly lower nocturnal carbon assimilation rates and higher stem volume-to-surface area ratios were found in CAM plants in mixture than in monoculture. Our study suggests that C4 grasses may outcompete CAM plants through greater access to deep soil water under increased rainfall variability and highlights the important role of hydrologic conditions as determinants of the competitive relations between CAM plants and grasses, their community composition, and ecological resilience in dryland ecosystems.

A study on the capability of the NCEP-CFS model in simulating the frequency and intensity of high-intensity rainfall events over Indian region in the high and low resolutions

In the current perception of an increase in extreme precipitation events in a developing and densely populated country like India and the demands of high resolution forecast runs are high, the present study compares the statistical skill of free runs from an operational climate model run in two horizontal resolutions in simulating the frequency and intensity of extreme rainfall events over Indian region. The operational climate model is a version of the National Center for Environmental Prediction (NCEP, USA) Climate Forecast System (CFS) version 2. It is run at two horizontal resolutions: CFST126 and CFST382, which is used for seasonal and extended range prediction in real-time in the India Meteorological Department’s (IMD) operational forecast framework. From the analysis of departure and bias of both the components of the model with respect to India Meteorological Department’s (IMD) observation, it is observed that marked dissimilarity in simulating high-intensity rain events exists between this two versions of the same model which should be hypothetically same. Both the models capture intensity and frequency differently. The main conclusions are (a) CFST126 free run gives better estimates of the frequency of rainfall events compared to CFST382, (b) CFST382 free run gives better estimates of the intensity of rainfall events compared to CFST126. These discrepancies indicate the resolution dependence of the statistics of extreme event, which should be statistically corrected and a multi-resolution ensemble version runs of CFSv2 has to be used for operational outlooks of the extreme events.

Influence of Climate Change on the Design of Retention Basins in Northeastern Portugal

Retention basins are used to control the quantity and quality of stormwater runoff. Their design is based on Intensity-Duration-Frequency (IDF) curves and on the assumption that the rainfall distribution is stationary. The analysis of rainfall observed for recent past conditions and projected for the future suggests the existence of significant changes in the frequency and intensity of extreme rainfall events. This study aims to assess the potential impacts of climate change in the design of retention basins. The adopted multi- and interdisciplinary methodological approach comprises: Rainfall aggregation and disaggregation, distribution fitting for different climate change scenarios, durations and return periods, model bias correction, robust regression of rainfall intensity for different durations and, finally, engineering design based on IDF curves. Results obtained with IDF curves defined in the Portuguese law and estimated from the ECHAM5/MPI-OM1/COSMO-CLM regional climate model for recent past and future climate scenarios point to: (i) Increase in the volume of the retention basin, more expressive in the end of the XXI century; (ii) changes of different magnitude within the country and the same rainfall region; and (iii) increase of 20% to 23% on average, and 46% to 65% at most, for the conditions of B1 and A1B scenarios, respectively.

Hydrometeorological assessments and suspended sediment delivery from a central Himalayan glacier in the upper Ganga basin

Integrated hydrometeorological investigations are not frequently available at a regional scale over a longer time period, especially near the terminus of Indian Himalayan glaciers. An integrated approach to the collection of hydrological data has major advantages for understanding the runoff generation mechanisms at basin scale, particularly when coupled with meteorological observations. The current study involves time series analysis of hydrometeorological records collected near the terminus of the Chorabari Glacier, for four consecutive ablation seasons (June–Sept.) 2009–2012. The analysis shows that variation in rainfall was higher (cv = 0.9) at the same elevation over proximal sites, while the intensity of extreme rainfall events was 121–160 mm/d. The diurnal temperature range (DTR) has a tendency to reduce over the ablation season because of the onset of the Indian Summer Monsoon (ISM) and then further increases during the ISM withdrawal indicating humid-temperate conditions. The peak discharge (Qpeak) was found to be higher during July and August. Snow and glacier melt contributed 76% of the total suspended sediment transport during peak ISM months (July and August) reflecting seasonal evolution of the hydrologic conduits. The results indicate that Karakoram and western Himalayan glaciers produce comparatively low sediment yield compared to central Himalayan glaciers. The hydrological variations are depicted through flow duration curves (FDC) for meltwater discharge and sediment load. The flow corresponding to Q50, Q75, and Q90 (where Qx is the discharge that is exceeded x percent of the time referred to as % dependability) are 4.2, 3.7, and 2.8 m3/s; and the corresponding dependability for suspended sediment loads (SSLs) are 409.0, 266.0, and 157.2 t/d, respectively. The daily SSL and discharge (Q) from 2009 to 2012 were used to develop a sediment rating curve (SSL = 39.55 × Q1.588, R2 = 0.8). Multiple regressions are used to determine the impacts of meteorological parameters on glacier melt. The meteorological conditions, hydrological characteristics, and suspended sediment delivery for the Chorabari Glacier provide insight on meltwater generation processes and sediment transport patterns during the ISM season.

Developing IDF curve of extreme rainfall at Tan Son Hoa station for the period 1980-2015

Recently, the Intensity – Duration – Frequency (IDF) relationship of extreme rainfalls in a local area is usually investigated to provide accurate required data for calculating, planning, and developing urban drainage systems, especially in the context of climate change. Traditionally, IDF curves are computed based on a statistical method for analyzing the frequency of occurrence or non-occurrence of annual extreme rainfall events over a return period; or based on a probability distribution function of these events. However, these traditional methods do not take into consideration the relationship between extreme rainfalls of different durations as they only simulate the intensity of extreme rainfall events at each individual duration after generated a large number of parameter sets. Therefore, the results of these methods are inaccurate and much depend on the actual observed data. In this study, a new approach to develop IDF relations was proposed based on the scale-invariance nature of extreme rainfalls at different durations. This method will be examined and compared with traditional methods based on the IDF curves of extreme rainfalls at Tan Son Nhat gauge station (HCMC) from 1980 to 2015. Results have indicated that there is a linear relationship between extreme rainfalls at different time scales and showed that the proposed method is appropriate for estimating the IDF curves with many prominent advantages rather than traditional method.

Spatio-temporal variability and trends of precipitation and extreme rainfall events in Ethiopia in 1980–2010

This article summarizes the results from an analysis conducted to investigate the spatio-temporal variability and trends in the rainfall over Ethiopia over a period of 31 years from 1980 to 2010. The data is mostly observed station data supplemented by bias-corrected AgMERRA climate data. Changes in annual and Belg (March–May) and Kiremt (June to September) season rainfalls and rainy days have been analysed over the entire Ethiopia. Rainfall is characterized by high temporal variability with coefficient of variation (CV, %) varying from 9 to 30% in the annual, 9 to 69% during the Kiremt season and 15–55% during the Belg season rainfall amounts. Rainfall variability increased disproportionately as the amount of rainfall declined from 700 to 100 mm or less. No significant trend was observed in the annual rainfall amounts over the country, but increasing and decreasing trends were observed in the seasonal rainfall amounts in some areas. A declining trend is also observed in the number of rainy days especially in Oromia, Benishangul-Gumuz and Gambella regions. Trends in seasonal rainfall indicated a general decline in the Belg season and an increase in the Kiremt season rainfall amounts. The increase in rainfall during the main Kiremt season along with the decrease in the number of rainy days leads to an increase in extreme rainfall events over Ethiopia. The trends in the 95th-percentile rainfall events illustrate that the annual extreme rainfall events are increasing over the eastern and south-western parts of Ethiopia covering Oromia and Benishangul-Gumuz regions. During the Belg season, extreme rainfall events are mostly observed over central Ethiopia extending towards the southern part of the country while during the Kiremt season, they are observed over parts of Oromia, (covering Borena, Guji, Bali, west Harerge and east Harerge), Somali, Gambella, southern Tigray and Afar regions. Changes in the intensity of extreme rainfall events are mostly observed over south-eastern parts of Ethiopia extending to the south-west covering Somali and Oromia regions. Similar trends are also observed in the greatest 3-, 5- and 10-day rainfall amounts. Changes in the consecutive dry and wet days showed that consecutive wet days during Belg and Kiremt seasons decreased significantly in many areas in Ethiopia while consecutive dry days increased. The consistency in the trends over large spatial areas confirms the robustness of the trends and serves as a basis for understanding the projected changes in the climate. These results were discussed in relation to their significance to agriculture.

Extreme flooding mobilized dissolved organic matter from coastal forested wetlands

Two intense rainfalls [Hurricane Joaquin (2015) and Hurricane Matthew (2016)], one year apart, provided a unique opportunity to examine changes in dissolved organic matter (DOM) dynamics in coastal blackwater rivers under extreme flooding conditions in the southeastern United States. Two sites along Waccamaw River (a coastal blackwater river) and the outflow of 18 sub-basins of Yadkin-Pee Dee Basin were sampled during and after the flooding events. The peaks of dissolved organic carbon (DOC) and nitrogen (DON) concentrations were observed 18 and 23 days after peak discharge in 2015 and 2016, respectively. Moreover, DOM aromaticity and abundance of humic substances significantly increased during the same period. Separation of discharge hydrograph into surface runoff and subsurface flow suggested that temporal changes were mainly due to contributions from subsurface flow flushing organic matter from wetlands and organic-rich riparian zones. The spatial analysis highlighted the key role of the forested wetlands as the only land use that significantly correlated with both DOM quantity (DOC and DON load) and DOM composition (i.e., aromaticity). The Yadkin-Pee Dee River basin alone exported more than 474 million kg DOC into the ocean during high-flow conditions from the 2016 event, indicating that such extreme short-term events mobilized enormous amounts of organic carbon and nitrogen to the ocean. Considering the predicted increase in frequency and intensity of extreme rainfall events in the eastern U.S., the results of this study can shed light on changes in DOM dynamics that may occur under such conditions in the near future.

Changes in the patterns of extreme rainfall events in southern Brazil

ABSTRACTIn this study we have examined changes in frequency and intensity of extreme rainfall events for the state of Santa Catarina (SC) in southern Brazil during austral spring and summer. The results show that changes in El Niño‐Southern Oscillation (ENSO) between 1979–1999 and 2000–2015 due to different phases of Interdecadal Pacific Oscillation have an impact on the teleconnection patterns from the Pacific to South America. As a consequence, precipitation over SC in the late period is less likely to be linked to ENSO. Moreover, there have been changes not only in the frequency and intensity of extreme events between the two periods but also in the mechanisms that cause the extremes affecting the spatial distribution of the extremes. In spring, the extreme events are less likely to occur during El Niño events and more frequent during La Niña and neutral years. The classical mechanism, of an enhanced South Atlantic Lower Level Jet (SALLJ) bringing moisture to SC, is no longer responsible for the extremes in the spring. The current main mechanism is associated with the presence of frontal systems during ENSO years and the presence of the South Atlantic Convergence Zone (SACZ) to the north combined with an anticyclonic system off the South American coast during neutral years. As a consequence the extreme events are currently more frequent at stations in the eastern side of SC. In summer during neutral years, SACZ events have become less frequent at the same time that atmospheric blocking events have become more frequent, explaining the decrease in extremes. On the other hand, SACZ events have become more frequent during La Niña years and so do the extremes in SC, with El Niño events playing a less important role.

Impact of predicted precipitation scenarios on multitrophic interactions

Summary Predicted changes in the frequency and intensity of extreme rainfall events in the UK have the potential to disrupt terrestrial ecosystem function. However, responses of different trophic levels to these changes in rainfall patterns, and the underlying mechanisms, are not well‐characterised. This study aimed to investigate how changes in both the quantity and frequency of rainfall events will affect the outcome of interactions between plants, insect herbivores (above‐ and below‐ground) and natural enemies. Hordeum vulgare L. plants were grown in controlled conditions and in the field, and subjected to three precipitation scenarios: ambient (based on a local 10 year average rainfall); continuous drought (40% reduction compared with ambient); drought/deluge (40% reduction compared to ambient at a reduced frequency). The effects of these watering regimes and wireworm (Agriotes species) root herbivory on the performance of the plants, aphid herbivores above‐ground (Sitobion avenae, Metapolophium dirhodum, and Rhopalosiphum padi), and natural enemies of aphids including ladybirds (Harmonia axyridis) were assessed from measurements of plant growth, insect abundance and mass, and assays of feeding behaviour. Continuous drought decreased plant biomass, whereas reducing the frequency of watering events did not affect plant biomass but did alter plant chemical composition. In controlled conditions, continuous drought ameliorated the negative impact of wireworms on plant biomass. Compared with the ambient treatment, aphid mass was increased by 15% when feeding on plants subjected to drought/deluge; and ladybirds were 66% heavier when feeding on these aphids but this did not affect ladybird prey choice. In field conditions, wireworms feeding below‐ground reduced the number of shoot‐feeding aphids under ambient and continuous drought conditions but not under drought/deluge. Predicted changes in both the frequency and intensity of precipitation events under climate change have the potential to limit plant growth, but reduce wireworm herbivory, whilst simultaneously promoting above‐ground aphid numbers and mass, with these effects transferring to the third trophic level. Understanding the effect of future changes in the precipitation on species interactions is critical for determining their potential impact on ecosystem functioning and constructing accurate predictions under global change scenarios. A lay summary is available for this article.

Effect of climate change on stormwater runoff characteristics and treatment efficiencies of stormwater retention ponds: a case study from Denmark using TSS and Cu as indicator pollutants.

This study investigated the potential effect of climate changes on stormwater pollution runoff characteristics and the treatment efficiency of a stormwater retention pond in a 95 ha catchment in Denmark. An integrated dynamic stormwater runoff quality and treatment model was used to simulate two scenarios: one representing the current climate and another representing a future climate scenario with increased intensity of extreme rainfall events and longer dry weather periods. 100-year long high-resolution rainfall time series downscaled from regional climate model projections were used as input. The collected data showed that total suspended solids (TSS) and total copper (Cu) concentrations in stormwater runoff were related to flow, rainfall intensity and antecedent dry period. Extreme peak intensities resulted in high particulate concentrations and high loads but did not affect dissolved Cu concentrations. The future climate simulations showed an increased frequency of higher flows and increased total concentrations discharged from the catchment. The effect on the outlet from the pond was an increase in the total concentrations (TSS and Cu), whereas no major effect was observed on dissolved Cu concentrations. Similar results are expected for other particle bound pollutants including metals and slowly biodegradable organic substances such as PAH. Acute toxicity impacts to downstream surface waters seem to be only slightly affected. A minor increase in yearly loads of sediments and particle-bound pollutants is expected, mainly caused by large events disrupting the settling process. This may be important to consider for the many stormwater retention ponds existing in Denmark and across the world.