Design Storm Hyetographs Research Articles

Development of rainfall hyetographs for the North Coastal Area of Central Java

Abstract Temporal distribution of hyetograph is a significant data used by engineers for designing hydraulic structures and urban drainage systems. It is used to estimate peak flood discharge and flood volume. The design storm hyetograph need to be determined accurately before taking any hydrologic analyses. The North Coast of Central Java-Indonesia has been severely affected by flooding during the last two decades. So far, engineers have predicted flood discharge using hyetographs from elsewhere, even though the storm’s characteristics are local. The developed hyetograph in a certain region may not necessarily be adopted in different places. Therefore, it is necessary to develop local hyetographs. This article is aimed to develop hyetographs for the North Coast of Central Java-Indonesia. Analytical statistic approach to historical data is applied to develop the storm hyetographs. The results reveal that there was a difference between the Alternating Block Method (ABM) hyetograph, which tended to be symmetrical, and the hyetograph developed tended to skew to the left (positive skewness), with lower peak storm. It is recommended to evaluate the use of the ABM method in other locations in Indonesia by developing hyetographs based on historical rainfall data.

Rainfall analysis and deriving design storm for hydrological modelling of Koyna dam catchment area in Maharashtra state of India

Rainfall is a key hydro meteorological variable. Climate change is disrupting the hydrological cycle and altering the usual cycle of rainfall, which frequently results in long-lasting storms with significant rainfall. A first step in hydrologic design of project is to determine the design storm or rainfall events to be used. For deriving design storm, researchers concluded that instead of using generalized readily available curves or maps, it is better to estimate design storm based on site specific historical rainfall data. The objective of the study is to analyze the rainfall data in the koyna watershed area in order to evaluate the design storm, which will be further used as an input data for HEC-HMS event based hydrological modelling of flood peak attenuation of design storm flow at koyna dam during extreme rainfall event.In this study, 40 years (1982–2021) of rainfall data from 8 rain gauge stations in Koyna Dam Catchment area is used initially for performing trend analysis through statistical and graphical techniques and then for Isopluvial analysis. The Sen's slope test and the Mann-Kendall test are the statistical techniques employed, and Innovative Trend Analysis is the graphical technique used. IDF approach is used for deriving design storm, and using Gumbel's frequency distribution method Isohyetal maps, IDF tables and curves are prepared for 2,10,25,50,75 and 100 year return periods and 6,12,24,48 and 96 h durations. Results obtained from statistical and graphical trend analysis of annual rainfall series are consistent. No statistically significant trend in annual rainfall series is observed, however there is rising and falling trend was observed in annual as well as monthly rainfall series.From the results of design storm study, the design storm hyetograph of 10 years return period and 96 h duration is selected, which gives the rainfall intensity of 10.88 mm/h for the koyna catchment. There are various dams nearby koyna catchment, The Isohyet maps, IDF curves and table output available from this study can be more reliably used during planning and design of hydraulic structure for other areas near by koyna catchment.

Development of Rainfall Design Storm Hyetographs for Al-Quassim Region – Kingdom of Saudi Arabia

Development of Rainfall Design Storm Hyetographs for Al-Quassim Region – Kingdom of Saudi Arabia

High-resolution spatial analysis of the variability in the subdaily rainfall time structure

The paper is motivated by the generally large variability in the rainfall time structure during the events with high subdaily precipitation totals in Czechia, which should be taken into account when designing water management systems to handle precipitation. The presented spatial analysis of the variability in the rainfall time structure is based on the regional frequency analysis of the 6-h totals with a spatial resolution of 1 km. The totals are quantified with the synergy method using the weather-radar-derived precipitation intensities and the totals measured by rain gauges. The frequency analysis employs the progressive and robust region-of-influence method. Instead of only one design storm hyetograph, each site is characterized by the possible occurrence of six hyetographs that are synthetized from the heavy rainfalls in Czechia. The percentage of individual hyetographs for a given design precipitation depth is assessed through the combination of the frequency analyses of the totals with respect to and regardless of the course of precipitation. The spatial heterogeneity in the percentages is significantly affected by the topography and amplifies with the increasing return period of the totals. The six synthetic hyetographs are represented relatively evenly in the lowlands. In contrast, the mountainous areas are characterized by a notable increase in the percentages of events of long-lasting steady rain, which are triggered by their circulation causes together with the significant role of the orographic precipitation enhancements, particularly through the windward orographic lifting, which is mainly on the northern and eastern slopes of the mountains. Future research on the dependence between the return period of the events of a specific precipitation course and the magnitude of the antecedent totals might be even more applicable to hydrological modeling in small catchments.

A unified approach for hydrological modeling of arid catchments for flood hazards assessment: case study of wadi Itwad, southwest of Saudi Arabia

A unified and systematic approach for hydrological modeling is presented for assessing flood hazards in arid and semi-arid regions with wadi Itwad as a case study. The approach consists of the following steps: (1) estimation of the design storm duration, (2) estimation of the design rainfall depth, (3) development of the design storm hyetograph, (4) setup of the watershed hydrological system, (5) infiltration tests for estimate of soil characteristics, (6) land use and land cover analysis for curve number estimation, (7) how to incorporate dams (if any) and their reservoir characteristics for reservoir routing analysis, and (8) performing hydrological modeling under different scenarios, namely: lumped with and without the effect of dams and routed scenarios. An emphasis is made on the comparison between the SCS unit hydrograph and the unit hydrograph (UH) estimated for stream flow data. The UH method produces hydrographs that are typical of arid regions. It is characterized by a steep rising limb with a short time to peak, a rapid recession to zero base flow, and less flood volume due to transmission losses. The scenarios show that the lumped case overdesigns the protection schemes, while the lumped central basin with detention dams storing the flood water completely leads to underdesign in the downstream area. The routed scenario is more realistic, since it considers the detention dams with an overflow. The runoff volume (66.6 MCM) of the 10-year return period of the routed scenario is in the order of magnitude within the observed historical data (50 to 100 MCM) reported in the literature. The study concludes that the proposed approach is robust and takes into account the Saudi arid environment while performing flood risk assessment in KSA.

Generation of Synthetic Design Storm Hyetograph and Hydrologic Modeling under HEC HMS for Ziz Watershed

This article proposes a methodology for generating hourly rainfall from daily rainfall data. It was evolved as a tool for managing flood risks on Ziz catchment, by means of Intensity-duration-frequency curves (IDF) and designed hyetograph of Chicago. The study area is located in the south-eastern part of Morocco, and did not have a monitoring station for hourly rain measure, the methodomogy consist of determinating the rainfall intensity for 24 h using IDF, then estimating the hourly rainfall using Chicago formula, in order to assess the accuracy of the method the resulting hyetographs was introduced into the semi-distributed hydrological model HEC HMS to simulate hourly flow, which was compared to the observed one. The obtaining results exhibit that the observed value is positively correlated with those obtained by the above method, as shown by the correlation coefficient and the Nash-Sutcliffe. This approach can deal with instantaneous water management issues by tackling flood risks and providing an appropriate range of data for the dam’s management.

Assessing sub-daily rainstorm variability and its effects on flood processes in the Yangtze River Delta region

ABSTRACTTaking a representative catchment of the Yangtze River Delta region as the study area, this research evaluated sub-daily rainstorm variability and its potential effects on flood processes based on an integrated approach of the HEC-HMS model and design storm hyetographs. The results show that the intensities of rainfall on sub-daily scale are getting more extreme. The annual maximum 1-, 2- and 3-hour rainstorms followed significant upward trends with increases of 0.32, 0.43 and 0.44 mm per year, respectively, while the annual maximum 6-, 12- and 24-h events had non-significant rising trends. The detected significant trends in short-duration rainstorms were then used to redesign storm hyetographs to drive the HEC-HMS model, the results show that these changes in short-duration rainstorm characteristics would increase the flood peak discharge and flood volume. These findings indicate that regional flood control capabilities must be improved to manage the adverse impacts of rainfall variation under changing environments.

Urban flood analysis for different design storm hyetographs in Xiamen Island based on TELEMAC-2D

Urban flood analysis for different design storm hyetographs in Xiamen Island based on TELEMAC-2D

Comparative Assessment of Different Methods in Generating Design Storm Hyetographs for the Philippines

Design storm hyetographs are synthetic temporal rainfall patterns used as input for flood modeling studies, drainage design and hydrodynamic modeling. In practice, the Philippines adopts the alternating block (AB) method to derive hyetographs using PAGASA-synthesized rainfall intensity-duration-frequency (RIDF) curves. In this study, six other methods- AB from actual RIDF curve, actual normalized 24-hour storms and four different patterns derived by Huff (1967)- were tested using the tipping-bucket raingauge records of a local weather station. Nonparametric statistical tests were employed to determine the significant difference between and among distributions. Moreover, Chi-squared goodness-of-fit test was used to compare the hyetographs with data from actual storms. The PAGASA AB hyetographs, while accurate in some instances, do not always represent actual storms well. Furthermore, other methods may have better fits for other storms. This study recommends further research in establishing design hyetographs in the Philippines.

Development of design storm hyetographs in hyper-arid and arid regions: case study of Sultanate of Oman

The temporal distribution of the design storm is an important input in hydrological models. This research aims to develop design storm profiles representative of arid and hyper-arid areas based on actual storm recordings. Two hundred thirty-six rainfall storms were collected from seventeen rainfall gauges that cover the coastal zone of Oman for the period from 1993 to 2007. Storms were classified into four categories according to their total durations. Design storm hyetographs were derived from raw rainfall records for all four categories using the Alternating Block Method (ABM) and were also computed by ABM applied on the Intensity-Duration-Frequency (IDF) curves. Both design storm profiles were compared and it was found that the ABM_IDF storm profiles were equivalent to the four ABM_Storms profiles from a practical point of view as they produce similar peak discharges. The storm profiles developed in the current research were also compared to the commonly used Soil Conservation Service (SCS) dimensionless distributions and the UK50 storm profiles. The results showed that the most conservative commonly used SCS type II and the UK50 summer profiles are not safe to be used in design purposes in arid and hyper arid regions, despite their wide utilization in many codes of practice in these regions. The study recommends using the newly developed dimensionless storm profiles derived from the actual records.

Analyses of extreme precipitation and runoff events including uncertainties and reliability in design and management of urban water infrastructure

There is a need for assessment of uncertainties and hence effects on reliability of design and management of stormwater pipes due to the prevalence of urban floods trigged by modification of land cover and high precipitation intensities respectively due to increasing urbanization and changing climate.Observed annual maximum series (AMS) of extreme precipitation intensities of 17 durations (1-min to 1440-min) and runoff records of 27years from a 21.255ha (23% impervious, 35% built-up and 41% open areas) Risvollan catchment in Trondheim City were used. Using a balanced bootstrap resampling (BBRS) with frequency analysis, we quantified considerable uncertainty in precipitation and runoff quantiles due to the sampling variability of systematic observations (e.g., −43% to +49% relative differences from the quantile estimates for the original sample). These differences are higher than suggested increase in design rainfall and floods by many countries for climate change adjustment. The uncertainties in IDF curves and derived design storm hyetographs are found to have large effects on the reliability of sizing of stormwater pipes. The study also indicated low validity of the assumptions on extreme precipitation and runoff relationships in the return period-based method for the partially paved urban catchment: (i) maximum of only 46% of the AMS of extreme precipitation and runoff events occurred concurrently and (ii) T-year return period extreme precipitation events do not necessarily result in T-year flood events. These indicate that there are effects of snowmelt seasonality, and probably catchment moisture states and interactions between the flows in subsurface media and pipes. The results substantiate the need for better understanding of relationships between precipitation and runoff extremes and urban runoff generation process, and importance of uncertainty assessment and application of reliability-based methods for design and management of water infrastructure.

Future fluvial flood risks in Central Vietnam assessed using global super‐high‐resolution climate model output

AbstractFluvial flood risks are explored at the Vu Gia–Thu Bon River system in Central Vietnam based on a coupled hydrological–hydraulic model combined with design storm hyetographs constructed based on heavy rainfall downscaled from the output of a state‐of‐the‐art super‐high‐resolution (20‐km mesh) global climate model simulated under greenhouse gas emission scenario A1B. The results indicate that intensified rainfall due to future climate changes (2075–2099) will lead to higher flood risks in the fluvial plains, especially in the lower areas of the river system. The potential extent of inundation caused by a 25‐year return period flood in future climate patterns will increase by approximately 150% compared with those produced by the most severe flood in the present‐day climate (1979–2003). Moreover, the flood risks induced by a 10‐year return period flood tend to be slightly more severe than that of the 25‐year return period in the present‐day climate.

Development of storm hyetographs for flood forecasting in the Kingdom of Saudi Arabia

This paper presents the derivation of the design storm hyetograph patterns for the Kingdom of Saudi Arabia based on real rainfall events from meteorological stations distributed throughout the Kingdom. Two thousand twenty-seven rainfall storms for a 20–28-year period were collected and analyzed covering 13 regions of the Kingdom. Four distinct dimensionless rainfall hyetograph patterns have been obtained over the Kingdom, while two patterns have been obtained for each individual region because of the lack of data for long-duration storms in individual regions. The resulting dimensionless rainfall patterns for each region can be used to develop storm hyetographs for any design duration, total rainfall depth and return period. It has been shown that the developed storm hyetographs have different features from other storm patterns that are commonly used in arid zones. The study recommends using these curves for the design of hydraulic structures in Kingdom of Saudi Arabia and regions alike.

Role of rainfall events and imperviousness parameters on urban runoff modelling

The volume and rate of storm water runoff in an urban watershed depend directly on the precipitation magnitude as well as its spatial and temporal distribution over the catchment. The runoff simulation may be on the basis of continuous or event wise rainfall data. Event wise simulation requires a minimum of one design-storm hyetograph as input. In contrast, continuous runoff modelling incorporates the entire meteorological record (days, months or years) of the watershed as the input. Many a time, due to the non-availability of short-interval rainfall data, a continuous simulation is performed. The present study predicts the runoff in an urban north-east Indian catchment based on event wise and continuous simulation. Continuous modelling has been performed by taking the daily rainfall data as input file. Storm water management model has been used for runoff simulation. This would help to understand the variations in urban runoff modelling due to an event based and continuous rainfall input. Green Ampt model has been used for infiltration modelling. A comparison is presented between the predicted runoff from the continuous and event wise rainfall data by considering different imperviousness parameters. The simulated runoff is overestimated by the total impervious area (TIA) that disregards the type of connectivity to the collecting network.

Assessment of future flood intensification in Central Vietnam using a super-high-resolution climate model output

This paper presents an assessment of the changes in future floods. The ranked area-average heavy daily rainfall amounts simulated by a super-high-resolution (20 km mesh) global climate model output are corrected with consideration of the effects of the topography on heavy rainfall patterns and used as a basis to model design storm hyetographs. The rainfall data are then used as the input for a nearly calibration-free parameter rainfall–runoff model to simulate floods in the future climate (2075–2099) at the Upper Thu Bon River basin in Central Vietnam. The results show that although the future mean annual rainfall will not be considerably different compared to the present-day climate (1979–2003), extreme rainfall is projected to increase vigorously, leading to a similar order of intensification of future floods. It is very likely that the flood peak with a 25-year recurrence will increase approximately 42% relative to the present-day climate. The occurrence of floods with a 10-year recurrence may exceed those with a 25-year recurrence in the present-day climate. The projection results also exhibit insignificant uncertainties caused by an artificial neural network-based bias correction model. Additionally, the presented bias correction model shows advantages over a simple climatology scaling method.

Risk Assessment of Lake Flooding Considering Propagation of Uncertainty from Rainfall

AbstractRisk assessment of lake flooding is studied through uncertainty propagation of the rainstorm control model. The failure risks of insufficient drainage capacity are assessed using the classic reliability approach and time-dependent reliability approach separately. The rainstorm control model consists of three submodels: a design rainstorm model to determine design storm hyetograph, a rainfall-runoff model to generate inflow hydrograph of the lake, and a lake operation model to simulate the storage volume of lake. Monte Carlo simulation with stochastic rainfall is implemented to provide random input for the combined model. The effect of uncertainty propagation on the three submodels is examined. The developed methodology is demonstrated with a case study, and results reveal that it offers an appropriate technique to assess flooding risks and consider the effect of uncertainty propagation on urban storm water modeling in designing a new drainage plan.

A new approach to selecting a regionalized design hyetograph by principal component analysis and analytic hierarchy process

Designing storm hyetographs is the essential element of hydrologic modeling analysis and storm water drainage design. In order to reasonably use storm hyetograph design in an un-gauged area, a regional representative hyetograph from an alternative and uniform area must be found. A new approach is proposed in this study to select a regional design storm hyetograph using principal component analysis (PCA) and analytic hierarchy process (AHP). The proposed approach combines both PCA and cluster analysis techniques. Furthermore, the AHP method is also used to establish the regional design hyetograph. A case study applied in the area of northern Taiwan shows that our method can successfully categorize the area into three homogenous zones. A representative regional hyetograph can be obtained by selecting the largest priority vector or by the weighted average of rain gauges in each zone.

A probabilistic description of rain storms incorporating peak intensities

Summary Design storms with standardized hyetograph shapes and selected combinations of storm depths and durations are widely used in engineering hydrology. The key distinguishing feature between equal-duration design storms is their distinct intensity distributions. Differences in design storm hyetographs do not affect storm frequency, since only the frequency of the combination of storm depth and duration are determined through the use of Depth–Duration–Frequency curves. Probability distributions of peak intensity within rainfall events are not determined in current practice. Some current research applies copulas to joint distributions of rainstorm variables, but most of these are limited to bivariate distributions, and those that are developed for trivariate distributions do not address key variables important to everyday practice, or are limited by complexity of analysis. An alternative approach to characterizing peak storm intensity, intensity peak factor, together with its probability distribution is developed in this paper. An Archimedean copula is applied to describe the joint probability distribution of storm duration with intensity peak factor. That joint distribution is combined with the probability distribution of storm depth, to produce a joint probability distribution for storm depth, duration, and peak intensity. The result is a simple approach to fully characterizing the storm variables of direct interest to practitioners, thereby providing a complete probabilistic description of the return period or frequency of a selected design storm.

Temporal properties of rainfall events in Calabria (southern Italy)

Abstract. Temporal properties of 152 575 rainfall events, recorded at time steps of 5 min, having different durations and occurring between 1989 and 2008 at 155 localities of Calabria (Italy), have been analysed in this paper. Samples from 45 533 storms have been selected to classify rainfall events as "significant" with regard to their contribution to soil erosion, flooding and/or other geo-hydrological processes. The samples are representative of a wide variety of situations in terms of duration, total rainfall, intensity, etc. The use of standardized rainfall profiles (SRP) is proposed to describe the within-storm temporal pattern. The main attraction of this method lies in the fact that it is based on actual data of regional precipitation. Its weak point is that large samples of data are required to obtain regional profiles. The research necessities for improving the use of Huff curves for storm disaggregation and its the potential use are summarized in this paper on the basis of the specific literature. A new criterion – based on the comparison of the areas A1, A2, A3 and A4 that underlie the four 25% of durations of a given SRP, and the corresponding four values of the "uniform" SRP (USRP), is suggested here with the aim of improving the use of the information content of SRP. Some interesting results concerning the sample frequency and the characterization of parameters for hydrological applications are commented on. The study conducted so far has produced important, albeit preliminary, results for different contexts of Calabria concerning the use of SRP among the methods for constructing design storm hyetographs.

Regionalization of extreme precipitation estimates for the Alabama rainfall atlas

The Alabama Rainfall Atlas is an internet-based server for delivery of design information on the characteristics of extreme precipitation throughout the state. Products delivered include intensity-duration-frequency (IDF) curves and 24-h design storm hyetographs based on US Soil Conservation Service (now the Natural Resources Conservation Service) methods. Three databases (daily, hourly, subhourly) upon which the server relies consist of at-site estimates of generalized extreme value distribution parameters for gauging sites throughout the state. Regionalization of those at-site estimates to develop precipitation products for a user-specified location is accomplished using a hybrid estimation method that consists of a weighted average of estimators based on gauging station proximities and record lengths. The regionalization procedure provides products on demand for any user-selected location (gauged or ungauged) and does not cause discontinuities at boundaries that would result from delineation of distinct regions. The databases are compact and user-requested products are produced and delivered nearly instantaneously. These latter issues are felt to be major ones considering the internet-based delivery method.