scholarly journals Hillslope Contribution to the Clark Instantaneous Unit Hydrograph: Application to the Seolmacheon Basin, Korea

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1707
Author(s):  
Chulsang Yoo ◽  
Huy Phuong Doan ◽  
Changhyun Jun ◽  
Wooyoung Na
Keyword(s):  
Peak Flow ◽  
Peak Time ◽  
Rainfall Runoff ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Storage Coefficient ◽  
Channel Velocity ◽  
Linear Reservoir ◽  
Mountainous Basin

In this study, the time–area curve of an ellipse is analytically derived by considering flow velocities within both channel and hillslope. The Clark IUH is also derived analytically by solving the continuity equation with the input of the derived time–area curve to the linear reservoir. The derived Clark IUH is then evaluated by application to the Seolmacheon basin, a small mountainous basin in Korea. The findings in this study are summarized as follows. (1) The time–area curve of a basin can more realistically be derived by considering both the channel and hillslope velocities. The role of the hillslope velocity can also be easily confirmed by analyzing the derived time–area curve. (2) The analytically derived Clark IUH shows the relative roles of the hillslope velocity and the storage coefficient. Under the condition that the channel velocity remains unchanged, the hillslope velocity controls the runoff peak flow and the concentration time. On the other hand, the effect of the storage coefficient can be found in the runoff peak flow and peak time, as well as in the falling limb of the runoff hydrograph. These findings are also confirmed in the analysis of rainfall–runoff events of the Seolmacheon basin. (3) The effect of the hillslope velocity varies considerably depending on the rainfall events, which is also found to be mostly dependent upon the maximum rainfall intensity.

scholarly journals Evaluation of Rainfall Temporal Distribution Models with Annual Maximum Rainfall Events in Seoul, Korea

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1468 ◽  
Author(s):  
Wooyoung Na ◽  
Chulsang Yoo
Keyword(s):  
Root Mean Square Error ◽  
Peak Flow ◽  
Temporal Distribution ◽  
Mean Square ◽  
Annual Maximum ◽  
Block Method ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Pattern Correlation ◽  
Annual Maximum Rainfall

This study evaluated five models of rainfall temporal distribution (i.e., the Yen and Chow model, Mononobe model, alternating block method, Huff model, and Keifer and Chu model), with the annual maximum rainfall events selected from Seoul, Korea, from 1961 to 2016. Three different evaluation measures were considered: the absolute difference between the rainfall peaks of the model and the observed, the root mean square error, and the pattern correlation coefficient. Also, sensitivity analysis was conducted to determine whether the model, or the randomness of the rainfall temporal distribution, had the dominant effect on the runoff peak flow. As a result, the Keifer and Chu model was found to produce the most similar rainfall peak to the observed, the root mean square error was smaller for the Yen and Chow model and the alternating block method, and the pattern correlation was larger for the alternating block method. Overall, the best model to approximate the annual maximum rainfall events observed in Seoul, Korea, was found to be the alternating block method. Finally, the sensitivity of the runoff peak flow to the model of rainfall temporal distribution was found to be much higher than that to the randomness of the rainfall temporal distribution. In particular, in small basins with a high curve number (CN) value, the sensitivity of the runoff peak flow to the randomness of the rainfall temporal distribution was found to be insignificant.

scholarly journals The dominant runoff processes on grassland versus bare soil hillslopes in a temperate environment - An experimental study

2019 ◽  
Vol 67 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Gabriel Minea ◽  
Gabriela Ioana-Toroimac ◽  
Gabriela Moroşanu
Keyword(s):  
Overland Flow ◽  
Bare Soil ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Antecedent Precipitation ◽  
Temperate Environment ◽  
The Relationship

Abstract This paper aimed to investigate the dominant runoff processes (DRP’s) at plot-scale in the Curvature Subcarpathians under natural rainfall conditions characteristic for Romania’s temperate environment. The study was based on 32 selected rainfall-runoff events produced during the interval April–September (2014–2017). By comparing water balance on the analyzed Luvisol plots for two types of land use (grassland vs. bare soil), we showed that DRP’s are mostly formed by Hortonian Overland Flow (HOF), 47% vs. 59% respectively. On grassland, HOF is followed by Deep Percolation (DP, 31%) and Fast Subsurface Flow (SSF, 22%), whereas, on bare soil, DP shows a higher percentage (38%) and SSF a lower one (3%), which suggests that the soil-root interface controls the runoff generation. Concerning the relationship between antecedent precipitation and runoff, the study indicated the nonlinearity of the two processes, more obvious on grassland and in drought conditions than on bare soil and in wet conditions (as demonstrated by the higher runoff coefficients). Moreover, the HOF appeared to respond differently to rainfall events on the two plots - slightly longer lag-time, lower discharge and lower volume on grassland - which suggests the hydrologic key role of vegetation in runoff generation processes.

Rainfall Events as Paths of a Stochastic Process: Problems of Design Storm Analysis

1984 ◽  
Vol 16 (8-9) ◽  
pp. 131-138 ◽  
Author(s):  
Johannes Brummer
Keyword(s):  
Stochastic Process ◽  
Peak Flow ◽  
Rainfall Events ◽  
Peak Flows ◽  
Design Storm ◽  
Adequate Evaluation ◽  
Rainfall Patterns

Problems in the construction of design storms are expressed in mathematical terms. Introduced here is a concept for approximating natural peak flow values by means of the distribution of typical rainfall patterns. A comparison demonstrates the quality of this concept and the competency of some well-known design storms for the adequate evaluation of peak flows.

scholarly journals Analysis of the Behavior of Abstractions in Two Urban Micro-Basins of the City of Cuenca (Ecuador), through an Aggregate Model

2021 ◽  
Vol 13 (6) ◽  
pp. 3209
Author(s):  
Ricardo Rubio-Ramírez ◽  
Rubén Jerves-Cobo ◽  
Diego Mora-Serrano
Keyword(s):  
Stormwater Runoff ◽  
Great Sensitivity ◽  
Aggregate Model ◽  
Antecedent Soil Moisture ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Impervious Area ◽  
Process Of Urbanization ◽  
Negative Impacts ◽  
The City

Several cities in developing countries are challenging the permanent process of urbanization. This generates a great disturbance on the hydrological response of the urbanized area during rainfall events, which can cause floods. Among the disturbances that urbanized basins may suffer, it is found that variations in rain losses (hydrological abstractions) can be estimated by the named volumetric runoff coefficient (CVOL) methodology. In the present study, this methodology is used in an attempt to estimate the hydrological abstraction of two nearby urbanized basins, with different degrees of impermeability, located in the city of Cuenca in Ecuador. The data for that analysis were collected between April and May of 2017. The results obtained indicate that the micro-basin with the largest impervious area presents the higher initial hydrological losses, the higher rate of decrease in abstractions, and the higher stormwater runoff flows per unit area. In addition, the abstractions found in the two urban micro-basins show great sensitivity to the maximum rainfall intensity and do not relate to the antecedent soil moisture. These results demonstrate the importance of having higher pervious surfaces in urbanized areas because they lead to reduce negative impacts associated with increased stormwater runoff on impervious surfaces.

scholarly journals Stationary and Non-Stationary Frameworks for Extreme Rainfall Time Series in Southern Italy

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1477 ◽  
Author(s):  
Davide De Luca ◽  
Luciano Galasso
Keyword(s):  
Time Series ◽  
Climate Models ◽  
Southern Italy ◽  
Regional Climate ◽  
Data Series ◽  
Rainfall Time Series ◽  
Annual Maximum ◽  
Data Set ◽  
Maximum Rainfall ◽  
Rainfall Events

This study tests stationary and non-stationary approaches for modelling data series of hydro-meteorological variables. Specifically, the authors considered annual maximum rainfall accumulations observed in the Calabria region (southern Italy), and attention was focused on time series characterized by heavy rainfall events which occurred from 1 January 2000 in the study area. This choice is justified by the need to check if the recent rainfall events in the new century can be considered as very different or not from the events occurred in the past. In detail, the whole data set of each considered time series (characterized by a sample size N > 40 data) was analyzed, in order to compare recent and past rainfall accumulations, which occurred in a specific site. All the proposed models were based on the Two-Component Extreme Value (TCEV) probability distribution, which is frequently applied for annual maximum time series in Calabria. The authors discussed the possible sources of uncertainty related to each framework and remarked on the crucial role played by ergodicity. In fact, if the process is assumed to be non-stationary, then ergodicity cannot hold, and thus possible trends should be derived from external sources, different from the time series of interest: in this work, Regional Climate Models’ (RCMs) outputs were considered in order to assess possible trends of TCEV parameters. From the obtained results, it does not seem essential to adopt non-stationary models, as significant trends do not appear from the observed data, due to a relevant number of heavy events which also occurred in the central part of the last century.

scholarly journals Extreme Rainfall in the Mediterranean: What Can We Learn from Observations?

2013 ◽  
Vol 14 (3) ◽  
pp. 906-922 ◽  
Author(s):  
N. Rebora ◽  
L. Molini ◽  
E. Casella ◽  
A. Comellas ◽  
E. Fiori ◽  
...  
Keyword(s):  
Extreme Rainfall ◽  
Flash Floods ◽  
Rain Gauge ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Life Threatening ◽  
The Mediterranean ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ground Effects

Abstract Flash floods induced by extreme rainfall events represent one of the most life-threatening phenomena in the Mediterranean. While their catastrophic ground effects are well documented by postevent surveys, the extreme rainfall events that generate them are still difficult to observe properly. Being able to collect observations of such events will help scientists to better understand and model these phenomena. The recent flash floods that hit the Liguria region (Italy) between the end of October and beginning of November 2011 give us the opportunity to use the measurements available from a large number of sensors, both ground based and spaceborne, to characterize these events. In this paper, the authors analyze the role of the key ingredients (e.g., unstable air masses, moist low-level jets, steep orography, and a slow-evolving synoptic pattern) for severe rainfall processes over complex orography. For the two Ligurian events, this role has been analyzed through the available observations (e.g., Meteosat Second Generation, Moderate Resolution Imaging Spectroradiometer, the Italian Radar Network mosaic, and the Italian rain gauge network observations). The authors then address the possible role of sea–atmosphere interactions and propose a characterization of these events in terms of their predictability.

scholarly journals Rainfall and weather conditions inducing intense landslide activity in northern Spain (Deba, Guipúzcoa)

2020 ◽  
Author(s):  
Victoria Rivas ◽  
Juan Remondo ◽  
Jaime Bonachea ◽  
Javier Sánchez-Espeso
Keyword(s):  
Weather Conditions ◽  
Rainfall Threshold ◽  
Large Network ◽  
Antecedent Rainfall ◽  
Northern Spain ◽  
Rainfall Events ◽  
Landslide Activity ◽  
Long Time ◽  
Span 60

Abstract. The Deba area is intensely affected by frequent shallow landslides triggered by rainfall. Relationships between rainfall and landslides in northern Spain, particularly for rainfall events driving multiple movements simultaneously, have not been explored in depth so far. This contribution explores the role of rainfall in landslide activity during a quite long time span, (60 years), from a large network of rainfall gauges and a complete inventory of landslides, and utilizing three different strategies of analysis. 1,180 landslides have been inventoried, and 3,241 rainfall episodes automatically recognized and characterized in terms of rainfall amount, duration and intensity. Antecedent rainfall has also been considered. Six episodes of intense rainfall, which have produced multiple landslides (> 50 % of the recent past occurrences) have been identified. The analysis provides different results: the extraordinary character of the triggering rainfall has been assessed, the meteorological conditions associated to those extreme episodes have been recognized and empirical rainfall threshold producing multiple landslides has been found (I = 7.7D-0.428) and compared with others described in literature. Results show that multiple landslide occurrences are triggered by extreme convective rainfall, intense, short and with limited horizontal extent, as well as a marked summer-autumn seasonality, characteristic of Mediterranean climate.

scholarly journals Rainfall-runoff relationships at event scale in western Mediterranean ephemeral streams

2021 ◽  
Author(s):  
Roberto Serrano-Notivoli ◽  
Alberto Martínez-Salvador ◽  
Rafael García-Lorenzo ◽  
David Espín-Sánchez ◽  
Carmelo Conesa-García
Keyword(s):  
Western Mediterranean ◽  
Additive Models ◽  
Future Climate Change ◽  
Ephemeral Streams ◽  
Return Periods ◽  
Rainfall Runoff ◽  
Event Scale ◽  
Rainfall Events ◽  
Flow Generation ◽  
Terrain Characteristics

Abstract. Ephemeral streams are highly dependent on rainfall and terrain characteristics and, therefore, very sensitive to minor changes in these environments. Western Mediterranean area exhibits a highly irregular precipitation regime with a great variety of rainfall events driving the flow generation on intermittent watercourses, and future climate change scenarios depict a lower magnitude and higher intensity of precipitation in this area, potentially leading to severe changes in flows. We explored the rainfall-runoff relationships in two semiarid watersheds in southern Spain (Algeciras and Upper Mula) to model the different types of rainfall events required to generate new flow in both intermittent streams. We used a nonlinear approach through Generalized Additive Models at event scale in terms of magnitude, duration, and intensity, contextualizing resulting thresholds in a long-term perspective through the calculation of return periods. Results showed that the average ~ 1.2-day and <1.5 mm event was not enough to create new flows. At least a 4-day event ranging from 4 to 20 mm, depending on the watershed was needed to ensure new flow at a high probability (95 %). While these thresholds represented low return periods (from 4 to 10 years), the great irregularity of annual precipitation and rainfall characteristics, makes prediction highly uncertain. Almost a third part of the rainfall events resulted in similar or lower flow than previous day, emphasizing the importance of lithological and terrain characteristics that lead to differences in flow generation between the watersheds.

scholarly journals The role of catchment classification in rainfall-runoff modeling

2011 ◽  
Vol 8 (3) ◽  
pp. 6113-6153 ◽  
Author(s):  
Y. He ◽  
A. Bárdossy ◽  
E. Zehe
Keyword(s):  
Classification Scheme ◽  
Intrinsic Value ◽  
Climatic Conditions ◽  
Ungauged Basins ◽  
Classification Methods ◽  
Rainfall Runoff ◽  
Catchment Hydrology ◽  
Natural Classification ◽  
Runoff Modeling

Abstract. A sound catchment classification scheme is a fundamental step towards improved catchment hydrology science and prediction in ungauged basins. Two categories of catchment classification methods are presented in the paper. The first one is based directly on physiographic properties and climatic conditions over a catchment and regarded as a Linnaean type or natural classification scheme. The second one is based on numerical clustering and regionalization methods and considered as a statistical or arbitrary classification scheme. This paper reviews each category including what has been done since recognition of the intrinsic value of catchment classification, what is being done in the current research, as well as what is to be done in the future.

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