Short-duration Storms Research Articles

Frequency and Spatial Variability of European Record Floods

AbstractRegional envelope curves (RECs) have been used to characterize the flooding potential of regions worldwide. However, a comprehensive assessment for Europe is still missing. In this study we use the largest European flood database to quantify the magnitude of record floods, their dependence on catchment size, and the amount of available independent information, which is needed for estimatinig the REC's exceedance probability. We propose a framework for estimating REC parameters across large areas, consisting in partitioning the domain according to the observation density and estimating the REC slope through quantile regression. The results show that the REC parameters vary substantially across Europe. The envelope unit flood associated with a catchment area of 1,000 km2 varies between 0.1 and 6 m3s−1 km−2 and is highest in Mediterranean and Alpine areas and lowest in central‐eastern Europe. The slope of the envelope varies between 0 and −1 and is larger in Southern Europe than in Northern Europe. These differences are explained by steeper landscape in mountaineous regions and localized short duration storms producing large floods in small catchments in the Mediterranean, whose intensities are larger than in other parts of Europe. Based on the framework of probabilistic envelope curves we show that, despite the uneven observation density, the obtained RECs are associated with comparable exceedance probabilities.

Unveiling the Evolution of Extreme Rainfall Storm Structure Across Space and Time in a Warming Climate

AbstractClimate change induces significant changes in storm characteristics, particularly for short‐duration extreme storms (heavy rain features), impacting their intensity and spatio‐temporal distribution. Although alterations in precipitation intensity are well documented, past studies examining changes in spatio‐temporal distribution of storms (storm rainrates) were region‐specific and focused on isolated aspects of change in space or time, eluding a comprehensive understanding of the precise nature and extent of these changes. Bridging this gap, this study introduces a novel grid‐based measure of storm homogeneity, “spatio‐temporal homogeneity” metric and investigates the global patterns of change in combined spatio‐temporal characteristics of extreme storms. Analyzing the 30 min × 0.1° × 0.1° resolution Global Precipitation Measurements, the study finds that extreme storms are shrinking in both space and time due to rising surface air temperatures, predominantly in tropics. In contrast, temperate regions experience expanded extreme storms with increasing temperatures. The study also identifies a global trend toward more front‐loading in storms with rising temperatures, driven by a substantial increase in tropics and southern temperate regions. Conversely, storms in northern temperate regions become slightly more rear‐loaded as temperature increases. Furthermore, the study finds that characteristics of short–duration storms (6–12 hr) are more sensitive to temperature changes. Overall, this study contributes valuable insights into the global spatio‐temporal changes of extreme storms, highlighting regions most susceptible to alterations in storm patterns due to climate change. These findings are essential for developing effective adaptation strategies and flood management practices to cope with the changing nature of extreme storms in a warming climate.

Climate change impact and adaptation assessment for road drainage systems

Climate change exhibits a clear trend of escalating frequency and intensity of extreme weather events, posing heightened risks to drainage systems along the existing road networks. However, very few studies to date have investigated the consequences of projected future changes in rainfall on main road drainage and the resulting risk of road flooding. The work presented in this paper builds on the limited research by introducing a probabilistic model for assessing the impact of climate change on road drainage systems, incorporating climate uncertainty and drainage system variation. The probabilistic scenario-based model and associated framework offer a practical and innovative method for estimating the impact of short-duration storms under future climates for 2071–2100, in the absence of fine-resolution spatio-temporal data. The model also facilitates the assessment of the effectiveness of a climate adaptation strategy. An illustrative case-study of a road drainage system located in the south of Ireland is presented. It was found that the probability of road flooding during intense rainfall is projected to surpass the current acceptable limits set by Irish standards. Assessment of a proactive climate adaptation strategy implemented in 2015 indicated it may need to be adjusted to further reduce climate change impacts and optimise adaptation costs.

Understanding compound extreme precipitations preconditioned by heatwaves over China under climate change

Compared with individual heatwaves or storm events, the compound extreme precipitations preconditioned by heatwaves (CHEPs) usually amplify their adverse repercussions on both ecosystems and society. However, little is known about the physical mechanisms of generations, especially considering precipitation types triggered by various factors and synoptic patterns. By classifying extreme precipitations based on duration, we conduct an event-based analysis and comprehensively assess CHEPs using the machine learning-constrained framework and binning scaling methods over China. We find the fraction of CHEPs to total extreme short-duration/long-duration precipitations (ESDPs/ELDPs) has substantially increased by 18%/15% from 1979 to 2021, when using dry-bulb temperature to identify heatwaves. More notably, the hotspots of CHEPs are generally consistent with those of ESDPs. The ESDPs play a dominant role in shaping CHEPs episodes, which are governed by enhancing atmospheric instability due to preconditioned heatwaves. The horizontal moisture advection and transient vertical dynamic motion of moisture, which are paramount to LDPs, is not significantly enhanced by the overheating atmosphere, leading to a small fraction of LDPs to CHEPs. In addition, the intensity of ESDPs tends to increase with air temperature at higher rates than that of ELDPs. As short-duration storms may trigger severe flash floods, ample attention should be paid to the escalating risks of CHEPs under climate change.

Field based estimates of wave power at a nearshore Mediterranean locale for sustainable wave energy harnessing

Measurements from two Nortek/AWAC acoustic Doppler current profilers deployed for over three years at three sites were used to estimate the nearshore wave energy resource of the Gulf of Chania, in the island of Crete, Greece. Similar to other Mediterranean nearshore locations, low maximum and mean wave power values were observed, i.e., 133 and 2.57 kW/m at ∼20 m depth, respectively. Even though the study sites were in close proximity, considerable differences were observed, highlighting the nearshore effects of shoaling, refraction, and focusing on wave power estimates, and the need for long-term measurements. Short-duration storms (lasting a few days) with high wave power potentials were observed. During summer, the sea was much calmer. The nearshore wave power resource was found unsteady, with coefficients of variation well above 2, while the capacity factors of Pelamis and Oyster wave energy converters were 3.65% and 9.57%, respectively. As a result, existing technology is currently commercially unattractive for the Mediterranean nearshore. Marine renewable energy can play an important role in EU’s Blue Growth strategy and assist in meeting the 2050 carbon neutrality target. For this reason, research should focus on downscaling and redesigning wave energy technology to enable sustainable deployment in the Mediterranean nearshore.

Changes of hydro-meteorological trigger conditions for debris flows in a future alpine climate

Debris-flow activity is strongly controlled by hydro-meteorological trigger conditions, which are expected to change in a future climate. In this study we connect a regional hydro-meteorological susceptibility model for debris flows with climate projections until 2100 to assess changes of the frequency of critical trigger conditions for different trigger types (long-lasting rainfall, short-duration storm, snow-melt, rain-on-snow) in six regions in the Austrian Alps. We find limited annual changes of the number of days critical for debris-flow initiation when averaged over all regions, but distinct changes when separating between hydro-meteorological trigger types and study region. Changes become more evident at the monthly/seasonal scale, with a general trend of critical debris-flow trigger conditions earlier in the year. The outcomes of this study serve as a basis for the development of adaption strategies for future risk management.

Sub-Hourly to Daily Rainfall Intensity-Duration-Frequency Estimation Using Stochastic Storm Transposition and Discontinuous Radar Data

Frequency analysis of rainfall data is essential in the design and modelling of hydrological systems but is often statistically limited by the total observation period. With advances in weather radar technology, frequency analysis of areal rainfall data is possible at a higher spatial resolution. Still, the observation periods are short relative to established rain gauge networks. A stochastic framework, “stochastic storm transposition” shows great promise in recreating rainfall statistics from radar rainfall products, similar to rain gauge-derived statistics. This study estimates intensity–duration–frequency (IDF) relationships at both point and urban catchment scales. We use the stochastic storm transposition framework and a single high-resolution, 17-year long (however, discontinuous), radar rainfall dataset. The IDF relations are directly compared to rain gauge statistics with more than 40 years of observation, and rainfall extremes derived from the original, and untransposed, radar dataset. An overall agreement is discovered, however, with some discrepancies in short-duration storms due to scaling errors between gauge and radar.

Impacts of Rainstorm Characteristics on Runoff Quantity and Quality Control Performance Considering Integrated Green Infrastructures

Green infrastructure (GI) has been implemented globally to mitigate the negative effects of urbanization. GI also regulates the urban runoff process and reduces non-point source pollution by intercepting initial runoff pollution and stormwater storage. In this paper, the impacts on GI were quantified and analyzed, considering eight designed storms with a 24 h duration and eight others with a 2 h duration with the combination of two characteristics (return period and peak time). The runoff process and reduction effect of pollutants were simulated for GI combinations (green roofs, vegetative swale, bio-retention units, and permeable pavement) using the Storm Water Management Model, taking the Dongshan campus of Shanxi University as an example case study. The results show that the GI combination can reduce runoff, suspended solids (SS), and chemical oxygen demand (COD). For short- and long-duration rainstorms, the average reduction rates of runoff, SS, and COD were 39.7%, 38.8%, and 39.6%, and 36.5%, 31.7%, and 32%, respectively, indicating its better effectiveness for short-duration storms. The GI’s effect was more sensitive during the short-duration storms owing to the greater absolute value of the 2 h elastic coefficients versus that of the 24 h, and the best reduction effect was observed with a rainfall peak coefficient of 0.1. These results provide a scientific reference for GI planning and implementation under a changing climate in the future.

Spatiotemporal dynamics of suspended particulate matter in the Bohai Sea, China over the past decade from the space perspective

Suspended particulate matter (SPM) concentration is an important biogeochemical parameter for water quality assessment and morphodynamic studies. In this study, the four recent SPM retrieval models developed for Bohai Sea were evaluated using in situ datasets, and the best performing model was selected to investigate the spatiotemporal dynamics of SPM in Bohai Sea from 2011 to 2021 based on 1164 satellite imageries. The results indicated that the satellite-derived SPM concentrations had a high accuracy (R2 = 0.86, relative percentage difference = 33.71 %). The SPM concentrations in the Bohai Sea demonstrated a significant decadal decreasing trend (0.503 mg/L/yr), and the distribution area with low SPM (<30 mg/L) increased by 3.29 % annually. The southern Bohai Sea declined observably, involving the Bohai Bay (2.07 mg/L/yr), Laizhou Bay (1.916 mg/L/yr), and central Bohai Sea (−0.661 mg/L/yr). Monthly SPM was characterized by significant seasonality. The SPM circulation pattern in the Bohai Strait was generally northerly inflow and southerly outflow. Significant wave heights (Hs) dominated the SPM variations and explained 58.9 % of monthly SPM changes in the Bohai Sea. The strong waves reduction was the main reason for the decadal decline of SPM concentrations. Wind waves associated with monsoons controlled seasonal variations of SPM and promoted the output in winter through the southern Bohai Strait. Storms could cause a sharp increase in SPM concentrations, especially in Bohai Bay and Laizhou Bay which were highly sensitive to northerly winds and strong waves. After the storm ended, the effects of short-duration storm might fade away within a few hours, while that of long-duration storm could last for 2–3 days. High sediment transport from Yellow River (>500 × 104 t/M) controlled 74.8 % of monthly SPM variations within 3-km area off the estuary, 45 % of that within 5-km area, and 28.4 % of that within 10-km area.

Design Hyetograph for Short-Duration Rainstorm in Jiangsu

The rainstorm intensity formula and the design of rainstorm hyetographs are important aspects in drainage design standards. Against the backdrop of climate change, in most cities in Jiangsu Province of China, significant trends of increasing intensities of heavy rainfall are apparent. The parameters of the rainstorm intensity formula are no longer applicable in the current context of significantly stronger rainstorms. To adapt to this change, we first contrasted the fitting accuracy of the Gumbel distribution, the exponential distribution, and the Pearson III distribution for the rainstorm intensity formula in Jiangsu. It was found that the Gumbel distribution has the smallest relative mean square error in most cities, proving that it provides the best estimation of rainstorm intensity formula parameters. Therefore, the rainstorm intensity formula parameters for 13 cities was revised using the Gumbel distribution based on the rainfall data from 1991 to 2020. Then, the precipitation with a 100-year return period was calculated using the revised formula. Moreover, to compensate for the lack of storm hyetographs that have been designed for Jiangsu, we designed short-duration rainstorm hyetographs for 13 cities using the Chicago hyetograph method and the Pilgrim and Cordery (PC) method. The results show that most of the short-duration rainstorms lasted between 45 and 120 min and were dominated by single-peaked patterns, with the peak position typically occurring in the first half of the rainfall cycle. The peak coefficient distribution of short-duration rainstorms shows that short-duration rainstorms in the south reached their peak rainfall intensity earlier than those in the north. On this basis, using the Chicago method and PC method, short-duration storm hyetographs were designed, which could be used in the design of drainage systems to provide support in effectively reducing urban flood threats. By comparing the hyetographs with real short-duration rainstorm patterns, it was found that the precipitation process designed using the PC method was most similar to the actual precipitation process. However, the PC method was found to be highly dependent on local precipitation data, whereas only the rain peak coefficient is required to design the Chicago rainstorm hyetograph. Therefore, we primarily recommend hyetographs designed using the PC method for Jiangsu Province’s 13 major cities, while we recommend the Chicago hyetograph for the surrounding areas of the 13 cities that have no meteorological stations or lack data.

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.

Developing an integrated multiscale rainfall-runoff and inundation model: Application to an extreme rainfall event in Marikina-Pasig River Basin, Philippines

Study regionMarikina–Pasig basin, Philippines Study focusA multiscale rainfall-runoff and inundation model was developed to simulate the severe flooding caused by a high-intensity short-duration storm rainfall event in the urban domain. The model used the 2D shallow-water flow and finite volume schemes with second-order space–time accuracy to automatically incorporate the runoff into the flood inundation. The adaptive mesh refinement scheme—a variable grid-sizing technique—was implemented to dynamically refine the mesh from a watershed-scale to a more precise inundation in a subcatchment floodplain. The digital terrain and surface models were used to represent the variations in flood propagation along buildings and artificial barriers in the urban area. Additionally, the simulated flood depths and extent were validated by comparison with the observed data. New hydrological insightThe severe inundation produced by the extreme rainfall event was perceived to be caused by a combination of fluvial and pluvial flooding; exacerbated by the domain’s flat and low-lying elevation and its geographical features acting as a flood water receiving catchment accrued from the adjacent mountainous regions. The proposed method can be used to identify the flood depth and water accumulation, estimated peak time, potential flash-flood prone areas, and imperceptible flood origins without the need to establish first the water level and stream discharge boundary conditions. The domain-specific flood simulations can be used for early warning and to identify a broader scope of possible evacuation points during storm-based flooding events.

Estimation of Peak Discharges under Different Rainfall Depth–Duration–Frequency Formulations

One of the main signatures of short duration storms is given by Depth–Duration–Frequency (DDF) curves. In order to provide reliable estimates for small river basins or urban catchments, generally characterized by short concentration times, in this study the performances of different DDF curves proposed in literature are described and compared, in order to provide insights on the selection of the best approach in design practice, with particular reference to short durations. With this aim, 28 monitoring stations with time series of annual maximum rainfall depth characterized by sample size greater than 20 were selected in the Northern part of the Puglia region (South-Eastern Italy). In order to test the effect of the investigated DDF curves in reproducing the design peak discharge corresponding to an observed expected rainfall event, the Soil Conservation (SCS) curve number (CN) approach is exploited, generating peak discharges according to different selected combinations of the main parameters that control the critical rainfall duration. Results confirm the good reliability of the DDF curves with three parameters to adapt on short events both in terms of rainfall depth and in terms of peak discharge and, in particular, for durations up to 30 min, the three-parameter DDF curves always perform better than the two-parameter DDF.

An evaluation model for landslide and debris flow prediction using multiple hydrometeorological variables

Landslide and debris flows are typically triggered by rainfall-related weather conditions, including short-duration storms and long-lasting rainfall. The critical precipitation of landslides and debris flow occurrence is different under various hydrometeorological conditions. In this study, the trigger sensitivities of different daily hydrological variables were assessed using 50 days-worth of recorded landslide and debris flows using the Soil and Water Assessment Tool model. The event days were divided into long-lasting rainfall trigger (LLR-trigger) event days and short-duration storm trigger (SDS-trigger) event days with six determinate criteria based on modeled wetness states. The landslide and debris flow prediction model was built using nine hydrometeorological variables, and the predictive performance was tested with simulated data from 2010 to 2012. The results suggest that, except for rainfall, historical hydrological variables and their development provide important information for triggering landslides and debris flows. The prediction model with an area under curve (AUC) value of 0.85 was able to capture most of the landslides and debris flows. The temporal distribution of the two triggering events predicted by the model was consistent with the annual precipitation distribution. In addition, the spatial variations of the specific trigger types could be attributed to the different land covers. Despite some uncertainty, this study provides an idea of improving the landslide and debris flow prediction model.

Assessing Future Rainfall Intensity–Duration–Frequency Characteristics across Taiwan Using the k-Nearest Neighbor Method

This study analyzes the changes in rainfall intensities across Taiwan using the k-Nearest Neighbor method. Biases are corrected according to the identified discrepancy between the probability distribution of the model run and that of the observed data in the historical period. The projections of 21 weather stations in Taiwan under 10 (2RCP × 5GCM) scenarios for the near-(2021–2040) and far-future (2081–2100) are derived. The frequently occurred short-duration storm events in some regions decrease, but they are still vulnerable to flood considering the existing drainage capacities. More specifically, the land-subsidence region in the central, the landslide-sensitive mountainous region in the north and central, the pluvial- and fluvial-flood prone region in the north, and the eastern regions with vulnerable infrastructures should be especially aware of long-duration extreme events. Associations of the rainfall intensity with the different return period as well as the duration are further analyzed. The short-duration extreme events will become stronger, especially for 1-h events in the northern region and 1 or 2-h events in both the southern and eastern regions. In addition, places without experiences of long-lasting events may experience rainfall amounts exceeding 500 mm should be alert. Adaptation measures such as establishing distributed drainage system or renewing hydrological infrastructures in the eastern region are suggested considering the near future projection, and in the central and the southern regions for far future as well. Our findings can assist adaptation-related decision-making for more detailed stormwater/water resource management.

Influence of storm events on surf zone zooplankton in a Southwestern Atlantic sandy beach: A preliminary methodology using high-frequency physical data

Here we present a preliminary methodology and unprecedented data for sandy beach surf zones, focused on understanding the effects of the passage of storm events in surf- zooplankton communities. The main objectives of the present study were to analyze the variation of surf zone physical parameters during several storm events, which have occurred on Pehuen Co beach (PC), using high-frequency physical data and to explore the influence of these events on surf zooplankton taking into account some ecological community indicators such as taxa richness, abundance and diversity. We observed that the zooplankton community structure was significantly altered after the storms, mainly in terms of abundance, but also in the number of taxa and general diversity. In addition, important differences between storm duration were registered. The short-duration storms (< 6 h) were associated with an increase of zooplankton abundances after the events, whereas the long-duration ones (> 6 h) showed a sharp decrease in the number of organisms. Based on the present results, the coastal biological system could be completely altered during storm events, considering that the observed changes in the zooplankton community probably affect other species that interact with them, altering the trophic relationships in surf waters. Additionally, the high-frequency data provided us valuable information not only to visualize the hydrodynamic consequences of the storms, but also to explain the changes in the zooplankton community. The present contribution provides an initial step toward comprehensive research about the physical-biological interactions in surf zone waters during storms, even more in the actual context of climate change where extreme events are expected to increase in frequency and intensity.

Effects of a Permanent Soil Cover on Water Dynamics and Wine Characteristics in a Steep Vineyard in the Central Spain

The study of alternative soil managements to tillage, based on the evidence of climate change in the Mediterranean basin, is of great importance. Summer and autumn are critical seasons for soil degradation due to the high-intensity, short-duration storms. Vineyards are vulnerable, especially on steep slopes. The particular effects of storms over the years under different soil conditions due to different management practices are not frequently addressed in the literature. The aim of this study was to examine the differences between runoff and soil moisture patterns influenced by 2 treatments: traditional tillage (Till) and a permanent cover crop. A shallow-rooted grass species Brachypodium distachyon (L.) P. Beauv. with considerable density coverage was selected as cover crop. This annual species was seeded once in the first year and then allowed to self-seed the following years. Tillage was performed at least twice in spring to a 10- to 15-cm depth and once in late autumn at a depth of 20 to 35 cm. Rainfall simulation experiments were performed, 1 year after treatments, using high-intensity rainfall on closed plots of 2 m2, located in the middle strips of the vineyard with different treatments. The effects of simulated rainfall experiments were determined in 3 different moments of the growth cycle of cultivar: (1) in summer with dry soils, (2) in early autumn with moderate soil moisture, and (3) in autumn with wet soils. During the 2-year trial, the soil moisture level in the soil upper layer (0-10 cm) was higher for Till treatment (14.1% ± 2.4%) compared with that for cover crop treatment (12.3% ± 2.0%). However, soil moisture values were more similar between treatments at 35 cm depth (12% ± 1%), with the exception of spring and autumn; in spring, water consumption in the cover crop treatment was the highest, and the moisture level at 35 cm depth was reduced (12%) compared with that for Till treatment (13%). In autumn, in cover crop treatment, higher water infiltration rate in soils led to higher soil moisture content at 35 cm (11%) compared with that of Till treatment (10%). The effects of simulated rainfall experiments on runoff and infiltration under different soil conditions and management practices vary seasonally. Runoff was significantly higher in summer for cover crop treatment (11%) as compared with that for Till management (1%), but significantly lower (3%) with wetter soils than for Till treatment (22%) in autumn. Thus, the simulation experiments with wet soils using cover crops produced higher infiltration rates and, consequently, the higher soil moisture content in the following days. The difference between seasons is attributed to the greater porosity of soil under Till treatment in summer, which resulted from the shallow plowing (10-15 cm depth), carried out to reduce moisture competition between weeds. The effect of traditional spring plowing was short-lived. The infiltration of water increased by cover crop treatment as compared with tillage in autumn both before and after ripping. Management practices did not influence wine parameters, as no significant differences were found between wine organoleptic characteristics in the duo-trio wine tastings, similarly, no differences were found for alcoholic degree, acidity, reduced sugars, and pH; however, a trend for a positive increase in polyphenol contents was noticed. Therefore, properly managed to avoid water shortages, cover crops can be recommended for soil protection in semi-arid environments.

Choosing the LID for Urban Storm Management in the South of Taiyuan Basin by Comparing the Storm Water Reduction Efficiency

Low impact development (LID) is a storm management philosophy. This paper aims at choosing the LID for urban storm management by comparing the efficiency in the south urban district in the Taiyuan Basin. Firstly, we set up a 1D–2D model to simulate the hydrological and hydraulic process of the area. Then the efficiency of different LID scenarios was analyzed by ratio of surcharging pipeline, percentage of ponding road, external outflow, infiltration, surface runoff, facility storage, and LID area ratio. It was found that the continuous porous pavement and rain garden are beneficial for use in residential and commercial settings in urban areas, and the rain garden performs more effectively and efficiently than the continuous porous pavement. The area occupied by LID might be under 20% of the impervious building area, because the LID performance was not improved significantly with the LID area when the ratio exceeded 20%. The LIDs could be more useful for small return periods and short duration storms, and could not replace conventional runoff management practices and drainage systems.

Intensity-Duration-Frequency curves on short duration storms

Las curvas intensidad-duracion-frecuencia (IDF) se utilizan en hidrologia para caracterizar la intensidad de la lluvia en funcion de su duracion y su periodo de retorno. Estas curvas son de gran importancia en la planificacion de recursos hidricos, asi como para el diseno de obras hidraulicas. La ecuacion empirica propuesta por Sherman en 1931 sigue siendo utilizada en la actualidad. Los parametros de esta ecuacion se estiman por metodos de minimos cuadrados o de optimizacion. Sin embargo, los valores obtenidos para parametrizar esta ecuacion carecen de sentido fisico. Empleando datos de 523 tormentas monitoreadas a cada minuto se obtienen sus curvas IDF. Los resultados muestran que el parametro que ajusta el factor de escala de la formula de Sherman es funcion de la duracion tipica de las tormentas que se analizan. Se concluye que el factor de escala debe obtenerse de relaciones fisicas y no de metodos analiticos. Se recomienda que se revisen las curvas IDF, calculadas tradicionalmente, y se comparen las duraciones tipicas de tormenta con el factor de escala de la formula de Sherman.

Sustainable urban drainage systems: a tool to adapt combined sewer systems to climate change

Climate change is a big challenge that may affect water and sanitation services. The authors studied a strategy to adapt current infrastructure to adverse effects due to climate change, such as more frequent and heavier rainfall, through sustainable urban drainage systems (SUDS). A part of the sewer network of Santander, in Spain, is taken as a case study. After building the model under the SWMM-5 code, some scenarios were simulated, including short-duration storm analysis, under the current climate and with climate change estimation, for an extended period simulation. The same analysis was performed adding SUDS. Peak flow, energy consumption reductions and the total storm water volume disconnected were measured. Every action had a positive effect in adapting the existing infrastructure to climate change, but the authors observed that when SUDS worked together, the benefits were greater, as expected. Any future intervention might be focused on encouraging SUDS as a drainage solution, not as isolated pilot projects.