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1
Schärer, Lotte Askeland, Jan Ove Busklein, Edvard Sivertsen, and Tone M. Muthanna. "Limitations in using runoff coefficients for green and gray roof design." Hydrology Research 51, no. 2 (March 30, 2020): 339–50. http://dx.doi.org/10.2166/nh.2020.049.
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Abstract Climate change combined with urbanization increases the performance demand on urban drainage systems. Green roofs are one of the most used green infrastructure measures to alleviate the pressure on the urban drainage system through the detention and retention of runoff. The rational method with the runoff coefficient (C) is one of the most commonly used design tools for stormwater design in Norway. This method relies on a runoff coefficient being available for green roofs, which is typically not the case. This paper compares laboratory and experimental field studies to investigate runoff coefficients from different types of detention-based roofs. The methodology described in the German ‘FLL Guideline’, one of the world's most commonly used green roof standards, was used to measure the runoff coefficients for the different components making up a typical green roof. The contribution from each layer is reflected in the runoff coefficients. The runoff coefficients from the field experiments were calculated using observed precipitation and runoff from existing green roofs in Oslo, Trondheim, Sandnes, and Bergen, Norway. Events that had a cumulative precipitation comparable to the laboratory events, but longer durations, were selected. These events gave significantly lower and varying runoff coefficients, clearly demonstrating the limitation of choosing a suitable runoff coefficient for a given roof. However, laboratory experiments are important in understanding the underlying flow processes in the different layers in a detention-based roof.
2
Del Giudice, G., R. Padulano, and G. Rasulo. "Factors affecting the runoff coefficient." Hydrology and Earth System Sciences Discussions 9, no. 4 (April 17, 2012): 4919–41. http://dx.doi.org/10.5194/hessd-9-4919-2012.
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Abstract. The runoff coefficient φ is a crucial parameter for flood peak discharge estimate in ungauged drainage basins. Tables and graphs generally allow the determination of φ in a somewhat empirical way that can lead to inconsistency in application; therefore, it is important to identify other parameters that can be utilized to assess φ more directly. In the present paper, focusing on Southern Continental Italy, a simple analytical expression between runoff coefficient φ and soil potential maximum retention S is proposed; moreover, an improvement of this expression is provided by considering the pre-event moisture condition of the watershed through the use of a climatic factor. At this aim, the US Soil Conservation Service classification for soil permeability has been adopted, that allows the evaluation of S, according to its relationship with the runoff curve number CN, as a function of soil type, land use and antecedent soil moisture condition (AMC).
3
Şen, Zekai, and Abdüsselam Altunkaynak. "A comparative fuzzy logic approach to runoff coefficient and runoff estimation." Hydrological Processes 20, no. 9 (2006): 1993–2009. http://dx.doi.org/10.1002/hyp.5992.
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Zhao, Na Na, Fu Liang Yu, Chuan Zhe Li, Jia Liu, and Hao Wang. "An Experimental Study on the Rainfall-Runoff Progress of Wheat under Different Slope Angle." Advanced Materials Research 912-914 (April 2014): 1986–94. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1986.
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Rainfall-runoff process plays an important role in hydrological cycle, and the study on the rainfall-runoff will provide foundation and basis for research on basin hydrology and flood forecasting. In this paper, the surface runoff and subsurface flow of wheat were observed in the laboratory by artificial rainfall, and analyzed the cumulated surface runoff and recession process of subsurface flow by regression analysis. In addition, the factors affected the runoff and response of soil moisture on the runoff coefficients was also discussed. Results showed that the rainfall intensity, soil coverage and slope had important influence on the surface runoff generation, and the surface runoff was observed when the total rainfall amount exceeded 32mm and 13mm for 5°and 15° slope respectively. The cumulative surface runoff could be expressed as a power function, which had higher determination coefficient R2 (0.92~0.999). The subsurface flow was only observed at the ripening period and wheat stubble treatment, and mainly affected by slope angle and initial soil moisture, whereas rainfall intensity showed little impact. The recession curve of subsurface flow can be described as a simple exponential expression or power function, which the determination coefficient was 0.88 and 0.94 by regression analysis, respectively. Moreover, there was an obvious threshold (approximately 30%) between the average initial soil moisture and runoff coefficients, which the runoff increased significantly as above the threshold.
5
Zhang, Chao, Bo Fu Li, and Ying He Jiang. "Flush Rule and Initial Flush Analysis of Cement Concrete Pavement." Advanced Materials Research 941-944 (June 2014): 701–6. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.701.
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Road runoff was the major contribute to water body pollution. According to the cement concrete pavement flush was evaluated by artificial rainfall model, the experiment indicated that the runoff coefficient of cement concrete pavement was 0.85, the flush coefficient of dissolvable pollutant of road runoff flush model k was 0.082, and the flush coefficient of indissolvable pollutant of road runoff flush model k was 0.057. With the increasing cumulate runoff ratio, the initial flush coefficient kn was decreasing. The emission of 90% dissolvable pollutant and of 30% indissolvable pollutant was removed by 30% runoff.
6
Viglione, A., R. Merz, and G. Blöschl. "On the role of the runoff coefficient in the mapping of rainfall to flood return periods." Hydrology and Earth System Sciences 13, no. 5 (May 12, 2009): 577–93. http://dx.doi.org/10.5194/hess-13-577-2009.
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Abstract. While the correspondence of rainfall return period TP and flood return period TQ is at the heart of the design storm procedure, their relationship is still poorly understood. The purpose of this paper is to shed light on the controls on this relationship examining in particular the effect of the variability of event runoff coefficients. A simplified world with block rainfall and linear catchment response is assumed and a derived flood frequency approach, both in analytical and Monte-Carlo modes, is used. The results indicate that TQ can be much higher than TP of the associated storm. The ratio TQ /TP depends on the average wetness of the system. In a dry system, TQ can be of the order of hundreds of times of TP. In contrast, in a wet system, the maximum flood return period is never more than a few times that of the corresponding storm. This is because a wet system cannot be much worse than it normally is. The presence of a threshold effect in runoff generation related to storm volume reduces the maximum ratio of TQ /TP since it decreases the randomness of the runoff coefficients and increases the probability to be in a wet situation. We also examine the relation between the return periods of the input and the output of the design storm procedure when using a pre-selected runoff coefficient and the question which runoff coefficients produce a flood return period equal to the rainfall return period. For the systems analysed here, this runoff coefficient is always larger than the median of the runoff coefficients that cause the maximum annual floods. It depends on the average wetness of the system and on the return period considered, and its variability is particularly high when a threshold effect in runoff generation is present.
7
Abd-Elhamid, Hany F., Martina Zeleňáková, Zuzana Vranayová, and Ismail Fathy. "Evaluating the Impact of Urban Growth on the Design of Storm Water Drainage Systems." Water 12, no. 6 (May 31, 2020): 1572. http://dx.doi.org/10.3390/w12061572.
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Urban growth is one of the major causes of flooding in urban areas. This affects the runoff coefficients, which is among the most important factors that affect the design of storm water drainage systems. Changing the runoff coefficient will affect the design parameters of the drainage network, including outfall discharge, velocity, lag time and cost of construction. This study aims to assess the effect of changing the runoff coefficient due to urban growth on the design of a storm water drainage system. The hydrological models Hyfran, StormCAD and GIS are used to analyze different runoff coefficients. This study examines three zones in Dammam in the Kingdom of Saudi Arabia (KSA). The data developed from the models for the current case studies are used to develop an empirical equation to predict the max discharge for other catchments. The discharge is a function of the return period, runoff coefficient, drainage density, longest path, rainfall intensity and catchment area. To validate the developed equation, we use it to estimate the discharge in a real case study in South Korea. A comparison between the measured discharge and estimated discharge shows that the empirical equation is capable of predicting the maximum discharge for different catchments with high accuracy. Then, the validation of the models is carried out to determine the effect of the runoff coefficient on the design of a storm water drainage system in a case study in KSA. The results show that an increasing runoff coefficient due to urban growth increases the outfall discharge and velocity of storm water drainage systems, as well as affecting the cost of construction and decreasing the lag time. The cost increases by two to three times with increasing urbanization. This study provides a new perspective on the hydrologic impact of urban growth on the design of storm water drainage systems, which are essential for flood management. Moreover, the relationship between urban growth and the cost of storm drainage networks is explored, which could help decision makers to make appropriate judgements.
8
Chen, Xiaofei, Juraj Parajka, Borbála Széles, Peter Valent, Alberto Viglione, and Günter Blöschl. "Impact of Climate and Geology on Event Runoff Characteristics at the Regional Scale." Water 12, no. 12 (December 9, 2020): 3457. http://dx.doi.org/10.3390/w12123457.
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The dynamics of flood event characteristics, such as the runoff coefficient and the recession time constant, differ in time and space, due to differences in climate, geology, and runoff generation mechanisms. This study examines the variability of event runoff characteristics and relates them to climatic and hydro-geological characteristics available at the regional scale. The main focus is to examine the role of rainfall patterns (i.e., event precipitation volume, precipitation intensity, and antecedent precipitation) and runoff regime (i.e., initial flow before runoff event and event duration) characteristics on the seasonal dynamics of runoff response. The analysis is performed in four small Austrian catchments representing different hydro-geological settings obtained by field mapping. The results are based on an analysis of 982 runoff events identified from hourly measurements of streamflow and precipitation in the period 2002 to 2013. The results show that larger event runoff coefficients and flow peaks are estimated in catchments with high mean annual precipitation than in drier catchments. In contrast to some previous studies, the results show only poor relation between antecedent precipitation (as an index of catchment wetness) and event runoff response. The initial flow is found to be the main factor influencing the magnitude of runoff coefficient and event peaks in all analyzed catchments and geological settings. The recession time constant tends to be inversely related to the maximum event precipitation intensity, with an exception for one catchment (Wimitzbach), which is characterized by the largest proportion of deep interflow contribution to runoff. The analysis of the runoff response by different event types indicates that runoff coefficients and recession time constants are the largest for snowmelt runoff events.
9
LIU, Jianbo, Guangyao GAO, Shuai WANG, and Bojie FU. "Combined effects of rainfall regime and plot length on runoff and soil loss in the Loess Plateau of China." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 109, no. 3-4 (September 2018): 397–406. http://dx.doi.org/10.1017/s1755691018000531.
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ABSTRACTThe purpose of this paper was to study the interaction effects of rainfall regime and slope length on runoff and soil loss under different land uses. Event runoff and soil loss in forest, shrub and grass were measured in plots with lengths of 5, 9 and 13m in the Loess Plateau from 2008 to 2016. A total of 59 erosive rainfall events were recorded and classified into three rainfall regimes. Firstly, the results showed that the runoff coefficient was grass>shrub>forest, and soil loss was grass>forest>shrub, but the differences between forest and shrub in runoff and between grass and forest in soil loss did not reach significant levels. Secondly, rainfall regimes had an important effect on runoff and soil loss under different land uses. The lowest runoff coefficients and the highest soil loss in regime 2 were found in shrub and forest land, respectively, which differed from that of regime 1. In total, rainfall regime 1 had the highest runoff coefficient of 0.84–2.06%, followed by regime 3 with 0.33–0.88% and regime 2 with 0.04–0.06%. Soil loss in forest and grass land had a different order of regime 3>regime 1>regime 2. Thirdly, both the runoff coefficient and soil loss decreased with increasing plot length, while the effect of slope length on runoff/soil loss were influenced by land use type and rainfall regimes.
10
Sriwongsitanon, Nutchanart, and Wisuwat Taesombat. "Effects of land cover on runoff coefficient." Journal of Hydrology 410, no. 3-4 (November 2011): 226–38. http://dx.doi.org/10.1016/j.jhydrol.2011.09.021.
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Feng, P., and J. Z. Li. "Scale effects on runoff generation in meso-scale and large-scale sub-basins in the Luanhe River Basin." Hydrology and Earth System Sciences Discussions 5, no. 3 (June 19, 2008): 1511–31. http://dx.doi.org/10.5194/hessd-5-1511-2008.
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Abstract. The scale effects on runoff coefficients have been observed by several researchers on plots or small watersheds, however, little research has been done on meso-scale and large-scale catchments. So six meso-scale and large-scale sub-basins of the Luanhe river basin, in northeast of China, were selected for calculating the runoff coefficients of single event during 1956–2002. An obvious reduction in average runoff coefficients from 0.43 (Liuhe basin) to 0.10 (Luanhe basin) was found with increasing basin area. And for the annual runoff coefficients from 1956 to 2002, the same trend was also observed. In addition, runoff coefficients varied wildly from one rainstorm to the other. One of the reasons is that at the beginning of the storm, the rainfall is absorbed in the soil and fills in the macropores of the soil, and after runoff generation rainfall infiltrates during the routing process. And the spatial variability of rainfall, the groundwater discharge ability can also lead to runoff coefficients reduction with the increasing basin area. The study on the scale effects on runoff coefficient is very important to develop a physically-based hydrological model and parameter estimation on different scales.
12
Liu, Zheng Mao, Guang Liang Xia, Zhi Ke Chen, Ting Ting Sun, Pai Liu, Chao Du, Chao Qing, and Ya Shan Song. "Runoff Depth Variation Process and Driving Mechanism of Upper Reaches of Marsh Stream." Advanced Materials Research 550-553 (July 2012): 2571–79. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2571.
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Through the double mass curves analysis, it concluded that the relationship between the areal and the runoff depth within upper reaches of the Naoli River, the Naoli River basin had experienced a great change since 1963, especially the runoff coefficient which appeared in a decreasing trend. By adopting the runoff coefficient difference Rank and T test (α=0.05,n1=7,n2=43,T=255,T1α=108.52,T2α=248.47, T＞T2α＞T1α), it also concluded that there was no consistency between the runoff coefficient series from 1956 to 1962 and the ones from 1963 to 2005. By analyzing the frequency curves of precipitation-runoff depth, it indicated that, under the same precipitation frequency, the runoff coefficient in 1963-2005 was much smaller than that in 1956-1962. The research results revealed that: (1) The precipitation was the key driving force to runoff variation; (2) The land use/cover changes posed by human activities was one of important causes contributing to runoff coefficient mutation in the catchment area; (3)The runoff depth variation was mainly controlled by the Longtouqiao reservoir and the water consumption was influenced by irrigation of paddy field since 2001.
13
Miardini, Arina, and Pranatasari Dyah Susanti. "Analysis Physical Characteristics of Land for Estimated Runoff Coefficient as Flood Control Effort in Comal Watershed, Central Java." Forum Geografi 30, no. 1 (August 3, 2016): 58. http://dx.doi.org/10.23917/forgeo.v30i1.1131.
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Watershed conditions in Indonesia have been degraded over time, which is marked by increasing area of critical land. The vast area of critical land was evidenced to be a serious threat for watershed carrying capacity which eventually affected the hydrology imbalance in the watershed area. One among watershed with degraded lands which seriously requires priority handling is Comal watershed. The purpose of this study is to identify the physical characteristics of Comal watershed which have significant influence in determining the runoff and calculating the runoff coefficient by taking into account the parameters of watershed’s physical characteristics. The method used in this analysis is Cook method, which is done through the estimation of runoff coefficient by evaluating the parameters of slope, infiltration, vegetation cover, and drainage density. The unit of analysis in this study is land mapping unit. Results of the four parameters are classified and the classification is done so that the scores of the runoff coefficient are figured out, while the peak discharge determination is performed by using the Rational method. The analysis showed that runoff coefficient of Comal watershed is 61.63%, which can be categorized as high. The runoff coefficients and peak discharge calculations of each sub watershed, respectively, Comal Hilir of 52.65% with peak discharge 505.68 m3/sec, Genteng of 65.04% with peak discharge 542.44 m3/sec, Lomeneng of 64.00% with peak discharge 194.23 m3/sec, Srengseng of 64.10% with peak discharge 270.46 m3/sec, and Wakung Hulu of 62.34% with peak discharge 686.64 m3/ sec. The most influential runoff coefficient factors are, respectively, infiltration rate, slope, vegetation cover, and drainage density. Flood control priority in Comal watershed should be preoccupied to increase the infiltration rate through a combination of three conservation techniques of mechanical, vegetative, and biology.
14
Liang, Shumin, and Richard Greene. "A high-resolution global runoff estimate based on GIS and an empirical runoff coefficient." Hydrology Research 51, no. 6 (July 24, 2020): 1238–60. http://dx.doi.org/10.2166/nh.2020.132.
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Abstract This paper reviews 110 years of global runoff estimation. By employing the method of ordinary least square regression on a sample region's runoff coefficient, an empirical formula of a runoff coefficient is calculated for China. Based on this empirical formula applied with a high-resolution grid of precipitation, runoff is calculated resulting in an equally high-resolution map of global runoff using a geographic information system (GIS). The main results are (1) the global total runoff volume is 47,884 km3, (2) the average runoff depth is 359 mm, (3) the interior drainage region's runoff volume is 1,663 km3, and (4) the average runoff depth is 58.4 mm. The results are compared with the results of the existing literature on global runoff. This study emphasizes the importance of runoff and groundwater recharge in arid and semi-arid regions where the estimation value of runoff depth is significantly increased.
15
Itsukushima, Rei. "Characteristics and Controlling Factors of the Drought Runoff Coefficient." Water 13, no. 9 (April 30, 2021): 1259. http://dx.doi.org/10.3390/w13091259.
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Increasing water demand due to population growth, economic development, and changes in rainfall patterns due to climate change are likely to alter the duration and magnitude of droughts. Understanding the relationship between low-flow conditions and controlling factors relative to the magnitude of a drought is important for establishing sustainable water resource management based on changes in future drought risk. This study demonstrates the relationship between low-flow and controlling factors under different severities of drought. I calculated the drought runoff coefficient for six types of occurrence probability, using past observation data of annual total discharge and precipitation in the Japanese archipelago, where multiple climate zones exist. Furthermore, I investigated the pattern of change in the drought runoff coefficient in accordance with the probability of occurrence of drought, and relationships among the coefficient and geological, land use, and topographical factors. The drought runoff coefficient for multiple drought magnitudes exhibited three behaviors, corresponding to the pattern of precipitation. Results from a generalized linear model (GLM) revealed that the controlling factors differed depending on the magnitude of the drought. During high-frequency droughts, the drought runoff coefficient was influenced by geological and vegetation factors, whereas land use and topographical factors influenced the drought runoff coefficient during low-frequency droughts. These differences were caused by differences in runoff, which dominated stream discharge, depending on the magnitude of the drought. Therefore, for effective water resource management, estimation of the volume of drought runoff needs to consider the pattern of precipitation, geology, land use, and topography.
16
Becciu, G., and A. Paoletti. "Random characteristics of runoff coefficient in urban catchments." Water Science and Technology 36, no. 8-9 (October 1, 1997): 39–44. http://dx.doi.org/10.2166/wst.1997.0641.
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In the paper an analysis of hydrological losses, observed during storm events recorded in experimental urban catchments, is presented. Random nature of runoff coefficient and its effects on peak discharge estimation are discussed. Simple relationships for estimation of main moments of runoff coefficient are presented.
17
Song, Xiaoyuan, Zhongyuan Zhu, XiaoKang Xi, Guibin Zhang, and Hailong Wang. "The Characteristics of Runoff Process Structure Changes under the Influence of Climate Change and Human Activities and the Decomposition of Contribution Rate of Impact Factors." Geofluids 2021 (January 6, 2021): 1–9. http://dx.doi.org/10.1155/2021/6673217.
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The research of the runoff structure and its influencing factors in the Xilinhe River Basin not only provides indispensable basic data for the economic development, but also has long-term significance for the protection of grasslands. Based on the runoff data of Xilinhot Hydrological Station from 1960 to 2010 and the daily meteorological data of three surrounding weather stations from 1960 to 2010, the paper calculated the potential evapotranspiration with Penman’s formula and used the combination of Mann-Kendall and Pettitt to diagnose the variation points of characteristic value of runoff distribution during the year. The cumulant slope change rate method is used to quantitatively analyze the contribution rate of climate change and human activities to the uneven distribution coefficient and the complete adjustment coefficient of runoff during the year. The results show that (1) the monthly distribution of runoff in the Xilinhe River Basin is obviously “bimodal” during the year, and the uneven coefficient, complete adjustment coefficient, and concentration in the 2000s are significantly higher than those of 60s-90s. (2) In 1998, the coefficient of uneven distribution of runoff in the Xilinhe River Basin and the coefficient of complete adjustment both showed abrupt changes. (3) Climate change and human activities contributed 11.48% and 88.52% and 9.35% and 90.65% to the uneven distribution coefficient and the complete adjustment coefficient, respectively, of the runoff in the Xilinhe River Basin. Human activities are the main driving factors for changes in the distribution of runoff in the Xilinhe River Basin during the year.
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Song, Xiaoyuan, Zhongyuan Zhu, XiaoKang Xi, Guibin Zhang, and Hailong Wang. "The Characteristics of Runoff Process Structure Changes under the Influence of Climate Change and Human Activities and the Decomposition of Contribution Rate of Impact Factors." Geofluids 2021 (January 6, 2021): 1–9. http://dx.doi.org/10.1155/2021/6673217.
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The research of the runoff structure and its influencing factors in the Xilinhe River Basin not only provides indispensable basic data for the economic development, but also has long-term significance for the protection of grasslands. Based on the runoff data of Xilinhot Hydrological Station from 1960 to 2010 and the daily meteorological data of three surrounding weather stations from 1960 to 2010, the paper calculated the potential evapotranspiration with Penman’s formula and used the combination of Mann-Kendall and Pettitt to diagnose the variation points of characteristic value of runoff distribution during the year. The cumulant slope change rate method is used to quantitatively analyze the contribution rate of climate change and human activities to the uneven distribution coefficient and the complete adjustment coefficient of runoff during the year. The results show that (1) the monthly distribution of runoff in the Xilinhe River Basin is obviously “bimodal” during the year, and the uneven coefficient, complete adjustment coefficient, and concentration in the 2000s are significantly higher than those of 60s-90s. (2) In 1998, the coefficient of uneven distribution of runoff in the Xilinhe River Basin and the coefficient of complete adjustment both showed abrupt changes. (3) Climate change and human activities contributed 11.48% and 88.52% and 9.35% and 90.65% to the uneven distribution coefficient and the complete adjustment coefficient, respectively, of the runoff in the Xilinhe River Basin. Human activities are the main driving factors for changes in the distribution of runoff in the Xilinhe River Basin during the year.
19
Ha, Ghafouri Azar, and Bae. "Long-Term Variation of Runoff Coefficient during Dry and Wet Seasons Due to Climate Change." Water 11, no. 11 (November 17, 2019): 2411. http://dx.doi.org/10.3390/w11112411.
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This study investigates the future long-term variation of the runoff coefficient during dry and wet seasons in five major basins in South Korea. The variation is estimated from the Soil and Water Assessment Tool (SWAT) model outputs based on an ensemble of 13 different Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs) in representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios. The estimates show a temporal non-considerable increase rate of the runoff coefficient during the 21st century in both RCPs, in which the trend and uncertainty of the runoff coefficient in the dry season is projected as higher than that in the wet season. A sharp contrast between the trends of the two components of the runoff coefficient is found during the dry and wet seasons. Over the five major basins, a higher increase rate of runoff coefficient is projected in the northeastern part of the Han River basin and most of the area of the Nakdong River basin. The spatial variation in the runoff coefficient change also represents a relationship with the change in the percentage of each land cover/land use type over 109 subbasins, where the correlation of the wet-season runoff coefficient is calculated as higher than that of the dry season. This relationship is expected to vary with changes in temperature and precipitation during both seasons in three future periods.
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Bai, Tian, Klaudia Borowiak, Yawen Wu, and Jingli Zhang. "Highly Resolved Runoff Path Simulation Based on Urban Surface Landscape Layout for Sub-Catchment Scale." Water 13, no. 10 (May 12, 2021): 1345. http://dx.doi.org/10.3390/w13101345.
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The present study explored the regularities of the path and network structure of surface runoff formed under the influence of urban surface landscapes. We used unmanned aerial vehicle sensors to examine terrain and land use/cover change. The sub-catchments of a typical city, Luohe, China, were evaluated for the effect of landscape on surface runoff. Landscape and topographic parameters from 166 urban sub-catchments in Luohe were obtained by measuring digital surface models and orthophoto maps. The minimum cumulative resistance model was used to simulate potential runoff and 491,820 potential runoff paths, connected upstream and downstream, were obtained in 166 sub-catchments. The chi-square test was used to compare simulation runoff paths and actual runoff depth, with the results showing that they led to the same distribution trend. When the gravity coefficient was greater than 18.93, path disconnection occurred among 166 sub-catchments, with a decrease in channels. The potential runoff distribution appeared in aggregation; as the gravity coefficient increased from low to high, aggregation showed a trend of increasing initially but subsequently decreasing. The initial runoff formed sub-catchments with high gravity coefficients, then accumulated and spread to the others. It is important that proper measures are taken to establish a unified planning of the city’s surface landscape in order to produce suitable surface runoff distribution.
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Gholami, Leila, Kazimierz Banasik, Seyed Hamidreza Sadeghi, Abdulvahed Khaledi Darvishan, and Leszek Hejduk. "Effectiveness of Straw Mulch on Infiltration, Splash Erosion, Runoff and Sediment in Laboratory Conditions." Journal of Water and Land Development 22, no. 1 (October 28, 2014): 51–60. http://dx.doi.org/10.2478/jwld-2014-0022.
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Abstract Mulches have extraordinary potential in reducing surface runoff, increasing infiltration of water into the soil and decreasing soil erosion. The straw mulches as a biological material, has the ability to be a significant physical barrier against the impact of raindrops and reduce the detachment of soil aggregates. The present study is an attempt to determine the efficiency of straw mulch as conservation treatment in changes in the splash erosion, time-to-runoff, runoff coefficient, infiltration coefficient, time-to-drainage, drainage coefficient, sediment concentration and soil loss. The laboratory experiments have been conducted for sandy-loam soil taken from deforested area, about 15 km of Warsaw west, Poland under lab conditions with simulated rainfall intensities of 60 and 120 mmh–1, in 4 soil moistures of 12, 25, 33 and 40% and the slope of 9%. Compared with bare treatments, results of straw mulch application showed the significant conservation effects on splash erosion, runoff coefficient, sediment concentration and soil loss and significant enhancement effects on infiltration and drainage. The results of Spearman-Rho correlation showed the significant (p < 0.05) correlation with r = –0.873, 0.873, 0.878 and 0.764 between rainfall intensity and drainage coefficient, downstream splash, sediment concentration and soil loss and with r = –0.976, 0.927 and –0.927 between initial soil moisture content and time-to-runoff, runoff coefficient and infiltration coefficient, respectively.
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Viglione, A., R. Merz, and G. Blöschl. "On the role of the runoff coefficient in the mapping of rainfall to flood return periods." Hydrology and Earth System Sciences Discussions 6, no. 1 (January 30, 2009): 627–65. http://dx.doi.org/10.5194/hessd-6-627-2009.
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Abstract. While the correspondence of rainfall return period TP and flood return period TQ is at the heart of the design storm procedure, their relationship is still poorly understood. The purpose of this paper is to shed light on the controls on this relationship examining in particular the effect of the variability of event runoff coefficients. A simplified world with block rainfall and linear catchment response is assumed and a derived flood frequency approach, both in analytical and Monte-Carlo modes, is used. The results indicate that TQ can be much higher than TP of the associated storm. The ratio TQ/TP depends on the average wetness of the system. In a dry system, TQ can be of the order of hundreds of times of TP. In contrast, in a wet system, the maximum flood return period is never more than a few times that of the corresponding storm. This is because a wet system cannot be much worse than it normally is. The presence of a threshold effect in runoff generation related to storm volume reduces the maximum ratio of TQ/TP since it decreases the randomness of the runoff coefficients and increases the probability to be in a wet situation. We also examine the question which runoff coefficients produce a flood return period equal to the rainfall return period if the design storm procedure is applied. For the systems analysed here, this runoff coefficient is always larger than the median of the runoff coefficients that cause the maximum annual floods. It depends on the average wetness of the system and on the return period considered, and its variability is particularly high when a threshold effect in runoff generation is present.
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Liu, Tong, Tsuyoshi Kinouchi, Javier Mendoza, and Yoichi Iwami. "Glacier Mass Balance and Catchment-Scale Water Balance in Bolivian Andes." Journal of Disaster Research 11, no. 6 (December 1, 2016): 1040–51. http://dx.doi.org/10.20965/jdr.2016.p1040.
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In investigating glacier mass balance and water balance at Huayna Potosi West, a glacierized basin in the Bolivian Andes (Cordillera Real), we used a remote sensing method with empirical area-volume relationships, a hydrological method with runoff coefficients, and water balance method. Results suggest that remote sensing method based on the glacier area from satellite images and area-volume relationships is too imprecise to use in performing analysis in short time intervals. Glacier mass balance obtained using a new area-volume relationship was, however, similar to that obtained by the water balance method, thus proving that the new area-volume relationship is reasonable to use for analyzing glaciers within a certain size range. The hydrological method with a runoff coefficient considered glacier as the only storage for saving or contributing to runoff and nonglacier area as the only source of evaporation. We applied a fixed runoff coefficient of 0.8 without considering wet or dry seasons in nonglacier areas – a method thus sensitive to meteorological and hydrological data. We also did not consider glacier sublimation. The water balance method is applicable to the study region and excelled other methods in terms of resolution, having no empirical coefficients, and considering sublimation and evaporation. Among its few limitations are possibly underestimating evaporation and runoff over nonglacier areas during wet months and thus possibly overestimating glacier contribution at mean time.
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Nganro, Sudirman, Slamet Trisutomo, Roland Alexander Barkey, and Mukti Ali. "ANALISIS KOEFISIEN LIMPASAN PERMUKAAN KOTA MAKASSAR DENGAN METODE COOK." TATALOKA 21, no. 2 (May 28, 2019): 285. http://dx.doi.org/10.14710/tataloka.21.2.285-292.
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Rain falling on the Watershed will turn into a stream in the river, this is because the rainwater is not entirely infiltrated into the soil, the unabsorbed water is called surface runoff. Factors affecting runoff are meteorological elements and drainage elements. This study aims to calculate the surface runoff coefficient using land cover maps 2017 and 2050, slope and soil type as parameters. Cook method divides the watershed characteristics into 4 sections as parameters to calculate the runoff coefficient of topography, soil type, vegetation cover and surface deposit. Each parameter is weighted based on its characteristics to calculate the coefficient of surface runoff symbolized by the letter C. The analysis results show that in the year 2017 obtained the value of C = 0.4734 and for the year 2050 C = 0.4785. There's a difference of 0.0051 coefficient of runoff value between land use map and land cover in 2017 and 2050. The results of this study will be used to calculate the flood discharge design in the object of research in Makassar City.
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Chou, Chien-ming. "Random Modeling of Daily Rainfall and Runoff Using a Seasonal Model and Wavelet Denoising." Mathematical Problems in Engineering 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/917365.
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Instead of Fourier smoothing, this study applied wavelet denoising to acquire the smooth seasonal mean and corresponding perturbation term from daily rainfall and runoff data in traditional seasonal models, which use seasonal means for hydrological time series forecasting. The denoised rainfall and runoff time series data were regarded as the smooth seasonal mean. The probability distribution of the percentage coefficients can be obtained from calibrated daily rainfall and runoff data. For validated daily rainfall and runoff data, percentage coefficients were randomly generated according to the probability distribution and the law of linear proportion. Multiplying the generated percentage coefficient by the smooth seasonal mean resulted in the corresponding perturbation term. Random modeling of daily rainfall and runoff can be obtained by adding the perturbation term to the smooth seasonal mean. To verify the accuracy of the proposed method, daily rainfall and runoff data for the Wu-Tu watershed were analyzed. The analytical results demonstrate that wavelet denoising enhances the precision of daily rainfall and runoff modeling of the seasonal model. In addition, the wavelet denoising technique proposed in this study can obtain the smooth seasonal mean of rainfall and runoff processes and is suitable for modeling actual daily rainfall and runoff processes.
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Kim, Nam, and Mun-Ju Shin. "Estimation of Peak Flow in Ungauged Catchments Using the Relationship between Runoff Coefficient and Curve Number." Water 10, no. 11 (November 16, 2018): 1669. http://dx.doi.org/10.3390/w10111669.
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Hourly flood flow estimation for gauged and ungauged catchments is a prerequisite for planning and water management. Various methods have been applied in a multitude of studies to calculate the peak flow for ungauged catchments. However, it is not simple for engineers to use the existing methods in practical applications. An easier method is suggested for this purpose in this study. The authors estimated the relationship between the runoff coefficient, intensity of rainfall, and curve number, and then utilized the relationship to calculated the peak flow using the rational method for ungauged catchments. Rainfall and flood time series for ungauged study catchments were generated by a simple data generation method and a distributed rainfall–runoff model. Results showed that the runoff coefficients simulated using the estimated relationship reasonably agree with the runoff coefficients in the studied ungauged catchments. In addition, the peak flow simulated using the rational method and the relationship highly agree with the peak flow in the ungauged catchments. Therefore, the peak flow in ungauged catchments can be easily calculated by this method, which is more pragmatic for engineers.
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Banasik, K., and L. Hejduk. "Long-term changes in runoff from a small agricultural catchment." Soil and Water Research 7, No. 2 (May 18, 2012): 64–72. http://dx.doi.org/10.17221/40/2011-swr.
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River runoff is an important indicator of environmental changes, which usually include climate and/or land use changes, and is also the basis of catchment water management. This study presents results of monitoring and analysis of 48-year precipitation and runoff from a small agricultural catchment located in central Poland. No land use changes in that period have been reported. Mean monthly distributions of precipitation and runoff for the long-term period showed that July was the wettest month in respect of precipitation and a drier one in respect of runoff, averaging 12.9% and 5.2% of their annual values, respectively. To evaluate the trend of three annual hydrometeorological parameters, i.e. precipitation, runoff and runoff coefficient, the Mann-Kendall test was applied. It indicated no trend in respect of precipitation, and decreasing trends of runoff and runoff coefficient at a 95% level of significance. Linear approximation of the annual runoff values indicated a decrease in runoff of ca. 1.2 mm per year for the analysed period. A few other functions were also used for better approximation of runoff data.
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Wang, D., and L. Wu. "Similarity between runoff coefficient and perennial stream density in the Budyko framework." Hydrology and Earth System Sciences Discussions 9, no. 6 (June 14, 2012): 7571–89. http://dx.doi.org/10.5194/hessd-9-7571-2012.
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Abstract. Streams are categorized into perennial and temporal streams based on flow durations. Perennial stream is the basic network, and temporal stream (ephemeral or intermittent) is the expanded network. Connection between perennial stream and runoff generation at the mean annual scale exists since one of the hydrologic functions of perennial stream is to deliver runoff. The partitioning of precipitation into runoff and evaporation at the mean annual scale, on the first order, is represented by the Budyko hypothesis which quantifies the ratio of evaporation to precipitation (E/P) as a function of climate aridity index (Ep/P, ratio of potential evaporation to precipitation). In this paper, it is hypothesized that similarity exists between perennial stream density (Dp) and runoff coefficient (Q/P) as a function of climate aridity index, i.e., DpDp* (EpP) and QP (EpP) where Dp* is a scaling factor and Q is mean annual runoff. To test the hypothesis, perennial stream densities for 185 watersheds in the United States are computed based on the high resolution national hydrography dataset (NHD). The similarity between perennial stream density and runoff coefficient is promising based on the case study watersheds. As a potential application for macroscale hydrological modeling, perennial stream density in ungauged basin can be predicted based on climate aridity index using the complementary Budyko curve.
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Gu, Jun Fang, Xiao Li Wang, and Fu Hui Du. "The Runoff Forecasting Model Based on Wavelet Adaptive Neural Fuzzy Inference System." Applied Mechanics and Materials 182-183 (June 2012): 1032–40. http://dx.doi.org/10.4028/www.scientific.net/amm.182-183.1032.
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Considering various the wavelet decomposition reconstruction technology and training cycle of adaptive neural fuzzy inference system, this article propose four runoff forecast model of wavelet analysis and adaptive neural fuzzy inference system integration, such as the long cycle based on Mallat algorithm in runoff prediction, the long cycle based on wavelet packet algorithm in runoff prediction, the short cycle based on Mallat algorithm in runoff prediction, the short cycle based on wavelet packet algorithm in runoff prediction, and illuminate the model of the principles, structures and procedures. This model is used in Tangnaihe station monthly runoff forecast which lies in the Huanghe source area. Simulation results are evaluated by the cycle decomposition coefficients and Nash-Sutcliffe coefficient; it shows that the long cycle based on Mallat algorithm is best, the short cycle based on wavelet packet algorithm is worst. The author analyzes the reason and makes some proposal.
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Toledo, Cristian Epifanio, João Carlos Mohn Nogueira, and Alexandre De Amorim Camargo. "Evaluation of water loss in transit and surface runoff in a Brazilian semi-arid basin." Ambiente e Agua - An Interdisciplinary Journal of Applied Science 15, no. 4 (July 6, 2020): 1. http://dx.doi.org/10.4136/ambi-agua.2545.
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The objective of this work was to propose and evaluate a model to estimate transit water losses and surface runoff in a Brazilian semi-arid basin, fundamental components in the hydrological studies of the region, such as in the verification of hydrological connectivity. The study area was the Orós Reservoir Basin, located in the state of Ceará. The modeling of transit water loss and surface runoff were developed based on the work of Araújo and Ribeiro (1996) and Peter et al. (2014). In the proposed model, the parameter of loss in transit (k) was estimated at 0.027 km-1 for a section of the river basin, and when simulated for other stretches it provided good flow results at the end of the stretch, obtaining an NSE of 82%. The value of the runoff coefficient was estimated at 3% and when evaluating a spatial variation of this coefficient in the basin, the values varied from 2% to 12%, and the use of specialized runoff coefficient (RC) values promoted a higher NSE in the discharge simulation in the basin. It is concluded that the proposed model to estimate transit water losses and surface runoff demonstrated a high efficiency in the simulation of hydrological processes. The basin of Orós reservoir presented a high variability of the coefficient of surface runoff, justifying the need for a greater spatiality of this coefficient in heterogeneous environments.
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Sishah, Shimelis. "Rainfall runoff estimation using GIS and SCS-CN method for awash river basin, Ethiopia." International Journal of Hydrology 5, no. 1 (March 22, 2021): 33–37. http://dx.doi.org/10.15406/ijh.2021.05.00263.
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Understanding hydrological behavior is an important part of effective watershed management and planning. Runoff resulted from rainfall is a component of hydrological behavior that is needed for efficient water resource planning. In this paper, GIS based SCS-CN runoff simulation model was applied to estimate rainfall runoff in Awash river basin. Global Curve Number (GCN250), Maximum Soil Water Retention (S) and Rainfall was used as an input for SCS-CN runoff simulation model. The final surface runoff values for the Awash river basin were generated on the basis of total annual rainfall and maximum soil water retention potential (S) of the year 2020. Accordingly, a runoff variation that range from 83.95 mm/year to a maximum of 1,416.75 mm/year were observed in the study region. Conversely, recently developed Global Curve Number (GCN250) data was tested with Pearson correlation coefficient to be used as an input for SCS-CN runoff simulation model. In doing so, predicted runoff generated in SCS-CN using GCN250 as a model input was validated with observed runoff obtained from station gauges in the study region. The results of validation show that, predicted runoff was well correlated with observed runoff with correlation coefficient of 0.9253. From this stand point, it is observed that the new GCN250 data can be used as an input for SCS-CN model to estimate rainfall runoff at basin level. Furthermore, correlation analysis was performed to explain the relationship between mean annual rainfall and surface runoff. The relationship between these two variables indicates a strong linear relationship with correlation coefficient of 0.9873.
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Chen, Xiaofei, Juraj Parajka, Borbála Széles, Peter Strauss, and Günter Blöschl. "Controls on event runoff coefficients and recession coefficients for different runoff generation mechanisms identified by three regression methods." Journal of Hydrology and Hydromechanics 68, no. 2 (June 1, 2020): 155–69. http://dx.doi.org/10.2478/johh-2020-0008.
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AbstractThe event runoff coefficient (Rc) and the recession coefficient (tc) are of theoretical importance for understanding catchment response and of practical importance in hydrological design. We analyse 57 event periods in the period 2013 to 2015 in the 66 ha Austrian Hydrological Open Air Laboratory (HOAL), where the seven subcatchments are stratified by runoff generation types into wetlands, tile drainage and natural drainage. Three machine learning algorithms (Random forest (RF), Gradient Boost Decision Tree (GBDT) and Support vector machine (SVM)) are used to estimate Rc and tc from 22 event based explanatory variables representing precipitation, soil moisture, groundwater level and season. The model performance of the SVM algorithm in estimating Rc and tc is generally higher than that of the other two methods, measured by the coefficient of determination R2, and the performance for Rc is higher than that for tc. The relative importance of the explanatory variables for the predictions, assessed by a heatmap, suggests that Rc of the tile drainage systems is more strongly controlled by the weather conditions than by the catchment state, while the opposite is true for natural drainage systems. Overall, model performance strongly depends on the runoff generation type.
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Volchak, Alexander, Sergey Parfomuk, and Svetlana Sidak. "Intra-annual Runoff Distribution in the Pripyat River Basin." E3S Web of Conferences 212 (2020): 01016. http://dx.doi.org/10.1051/e3sconf/202021201016.
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The time variability features of the intra-annual runoff distribution in the Pripyat River basin at the present stage are considered. The study used data from 10 active gauging-stations at the basin area for the period of enabled observations. Changes in the nature of natural runoff regulation of rivers are shown. An increase in the coefficient of natural runoff regulation after the period 1970-1983 for the rivers of the Pripyat River basin was revealed. The relationship between the coefficient of uneven runoff and the share of spring flood was established.
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Jeong, Yonggil, Jongpyo Park, and Hyunsuk Sin. "Correlation between LID Flood Control Capability and Runoff Coefficient." Journal of the Korean Society of Hazard Mitigation 20, no. 5 (October 31, 2020): 339–51. http://dx.doi.org/10.9798/kosham.2020.20.5.339.
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Short-term heavy rains caused by global warming could lead to urban flooding as well as damage to both people and property. Although Korea is taking active measures to reduce the impact of flood-related disasters through disaster impact assessments, these assessments mainly consist of qualitative evaluation procedures for urban inundation when designating districts for development projects. The recently developed “inundation determination and detention site size calculation program” has made it possible to review urban inundation hydraulic calculations, even when designating districts for development projects. However, there is still a limit to the hydraulic review and the utilization of Low Impact Development (LID) facilities due to the lack of linkage between the use of such facilities and the inundation determination program. Accordingly, it is necessary to develop a technique to utilize runoff coefficients in applying the LID in the flood determination program. Therefore, in this study, the flood control capacity of stormwater runoff reduction facilities at each LID facility was reviewed and the relationship with runoff coefficient was analyzed.
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Kohl, B., M. Fuchs, G. Markart, and G. Patzelt. "Heavy rain on snow cover." Annals of Glaciology 32 (2001): 33–38. http://dx.doi.org/10.3189/172756401781819139.
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AbstractHeavy rain on snow often leads to disastrous damages in torrent watersheds. In January 1998 a project was started to investigate “runoff and infiltration characteristics of different alpine soil/vegetation units under snow cover”. One aim was to determine the runoff rates from snow-covered, differently cultivated soil/vegetation units (pastures, dwarf-shrub stands, forests), especially under conditions of sparse snow cover and frozen soil. Differences in runoff formation between artificially snowed skiing areas and plots with natural snow cover were also of interest. Heavy rain (intensity 100 mm h–1) was simulated on four plots by using a transportable spray irrigation installation. The investigations showed runoff coefficients of 0.4–0.7. The lowest runoff values were found where the soil under snow cover was not frozen, but even on these stands the runoff coefficient exceeded 0.4. Snow depth and runoff delay are strongly correlated (R2 = 0.8). An increment in snow of 10 cm is followed by a runoff delay of 3.6 min. Divergences from this coherence are due to the composition of the snowpack, especially in case of artificial snow. This result is encouraged by runoff simulations performed for the irrigated plots by use of a hydrological model.
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Xiong, Lihua, and Shenglian Guo. "Effects of the catchment runoff coefficient on the performance of TOPMODEL in rainfall–runoff modelling." Hydrological Processes 18, no. 10 (June 22, 2004): 1823–36. http://dx.doi.org/10.1002/hyp.1449.
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Lallam, Faiza, Abdesselam Megnounif, and Abderrahman Nekkache Ghenim. "Estimating the runoff coefficient using the analytic hierarchy process." Journal of Water and Land Development 38, no. 1 (September 1, 2018): 67–74. http://dx.doi.org/10.2478/jwld-2018-0043.
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AbstractThe runoff coefficient (RC) is a parameter that is very often used in surface hydrology in order to characterize the drainage capacity of a watershed. The traditional estimate of this coefficient is often made from abacuses based on 2 or 3 parameters to the maximum. In this work, three numerical models are presented. Two models are based on experimental work. The first one is based on three criteria, namely the vegetation cover, the type of soil, and the slope. The second one considers the size of the watershed, the maximum daily rainfall and the type of soil. In practice, it is not easy to estimate the coefficient of runoff by simultaneously considering the influence of several criteria. In order to overcome this problem, a third model is developed and presented; it allows capitalizing the information from the first two models mentioned above. The objective of the present work is to be able to verify the comparability of these criteria and to assess the relative importance of each of them.
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Savenije, Hubert H. G. "The runoff coefficient as the key to moisture recycling." Journal of Hydrology 176, no. 1-4 (March 1996): 219–25. http://dx.doi.org/10.1016/0022-1694(95)02776-9.
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Şen, Zekai. "Instantaneous Runoff Coefficient Variation and Peak Discharge Estimation Model." Journal of Hydrologic Engineering 13, no. 4 (April 2008): 270–77. http://dx.doi.org/10.1061/(asce)1084-0699(2008)13:4(270).
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Baiamonte, Giorgio. "A rational runoff coefficient for a revisited rational formula." Hydrological Sciences Journal 65, no. 1 (November 8, 2019): 112–26. http://dx.doi.org/10.1080/02626667.2019.1682150.
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Preti, F., G. Forzieri, and G. B. Chirico. "Forest cover influence on regional flood frequency assessment in Mediterranean catchments." Hydrology and Earth System Sciences 15, no. 10 (October 7, 2011): 3077–90. http://dx.doi.org/10.5194/hess-15-3077-2011.
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Abstract. The paper aims at evaluating to what extent the forest cover can explain the component of runoff coefficient as defined in a regional flood frequency analysis based on the application of the rational formula coupled with a regional model of the annual maximum rainfall depths. The analysis is addressed to evaluate the component of the runoff coefficient which cannot be captured by the catchment lithology alone. Data mining is performed on 75 catchments distributed from South to Central Italy. Cluster and correlation structure analyses are conducted for distinguishing forest cover effects within catchments characterized by hydro-morphological similarities. We propose to improve the prediction of the runoff coefficient by a linear regression model, exploiting the ratio of the forest cover to the catchment critical rainfall depth as dependent variable. The proposed regression enables a significant bias correction of the runoff coefficient, particularly for those small mountainous catchments, characterised by larger forest cover fraction and lower critical rainfall depth.
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Yan, Shu, Zhong Yuan Zhang, Feng Lin Zuo, and Wei Hua Zhang. "A Comparative Study of Different Hydrological Model and their Application in Little River Catchment." Applied Mechanics and Materials 641-642 (September 2014): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amm.641-642.9.
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Sacramento, SimHyd and Tank model were selected and their structure, principles and characteristics were briefly described. Then by taking Little River Catchment in Georgia, USA as an example, the rainfall-runoff process was simulated by using the Rainfall Runoff Library. The results showed that: Nash-Sutcliffe coefficient reached more than 80% and RE (relative error coefficient of the total runoff) of Sacramento model also meets the requirements. Considering the Sacramento model is the best one on the Nash-Sutcliffe coefficient, the model is selected as the optimal model of Little River Catchment in this study.As the catchment is located in the southeastern USA, with humid climate, and saturated storage-based runoff generation, which is similar to Chongqing region, it provides relatively good reference for Chongqing as well as the entire southwestern region.
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Sadeghi, S. H. R., L. Gholami, E. Sharifi, A. Khaledi Darvishan, and M. Homaee. "Scale effect on runoff and soil loss control using rice straw mulch under laboratory conditions." Solid Earth 6, no. 1 (January 5, 2015): 1–8. http://dx.doi.org/10.5194/se-6-1-2015.
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Abstract. Amendments can control the runoff and soil loss by protecting the soil surface. However, scale effects on runoff and soil loss control have not been considered yet. The present study has been formulated to determine the efficiency of two plot sizes of 6 and 0.25 m2 covered by 0.5 kg m−2 of straw mulch with regard to changing the time to runoff, runoff coefficient, sediment concentration and soil loss under laboratory conditions. The study used a sandy-loam soil taken from summer rangeland, Alborz Mountains, northern Iran, and was conducted under simulated rainfall intensities of 50 and 90 mm h−1 and in three replicates. The results of the study showed that the straw mulch had a more significant effect on reducing the runoff coefficient, sediment concentration and soil loss on a 0.25 m2 plot scale. The maximum effectiveness in time to runoff for both the scales was observed at a rainfall intensity of 90 mm h−1. The maximum increasing and decreasing rates in time to runoff and runoff coefficient were observed at a rainfall intensity of 90 mm h−1, with 367.92 and 96.71% for the 0.25 m2 plot and 110.10 and 15.08% for the 6 m2 plot. The maximum reduction in the runoff coefficient was in the 0.25 m2 plot for the two rainfall intensities of 50 and 90 mm h−1, with rates of −89.34 and −96.71%. The maximum change in soil loss at the intensities of both 50 and 90 mm h−1 occurred in the 0.25 m2 plot, with 100%, whereas in the 6 m2 plot, decreasing rates of soil loss for the intensities of both 50 and 90 mm h−1 were 46.74 and 63.24%, respectively.
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KAVIAN, Ataollah, Leila GHOLAMI, Maziar MOHAMMADI, Velibor SPALEVIC, and Moghadeseh FALAH SORAKI. "Impact of Wheat Residue on Soil Erosion Processes." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 46, no. 2 (April 3, 2018): 553–62. http://dx.doi.org/10.15835/nbha46211192.
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Soil erosion is one of the key challenges in soil and water conservation. Vegetation that covers soil and organic and inorganic mulch is very useful for the control of erosion processes. This study examined treatment with wheat residual (as agriculture mulch) on infiltration, time to runoff, runoff coefficient, sediment concentration and soil erosion processes. The study has been conducted for sandy-loam soil taken from summer rangeland (Northern Iran) with simulated rainfall intensities of 50 and 100 mm h-1. The experiment was conducted in slopes of 30% in three replications with two amounts of wheat residual of 50 and 90 %. The results showed that conservation percent of soil erosion for wheat residual 50 and 90% was 61.68 and 73.25%, respectively (in rainfall intensity of 50 mm h-1). Also, the conservation percent of soil erosion for wheat residual of 50 and 90% cover was 70.68 and 90.55, respectively (in rainfall intensity of 100 mm h-1). It was concluded that the conservation treatments could reduce runoff coefficient, sediment concentration and soil erosion and increase the time to runoff and infiltration coefficient. This effect was significant on time for infiltration, sediment concentration and soil erosion variables (R2=0.99), time to runoff and runoff coefficient variables (R2=0.95). The interaction effects of rainfall intensity and soil conservation was significant for sediment concentration and soil erosion variables (R2=0.99).
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Sun, Jiamei, Dengxing Fan, Xinxiao Yu, and Hanzhi Li. "Hydraulic characteristics of varying slope gradients, rainfall intensities and litter cover on vegetated slopes." Hydrology Research 49, no. 2 (November 17, 2017): 506–16. http://dx.doi.org/10.2166/nh.2017.097.
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Abstract Litter produced by forests performs crucial functions in rainfall interception and soil conservation, particularly in the condition that larger raindrops formed by canopy accelerate soil erosion. To explore how forest litter exerts runoff hydrological characteristics and sediment yield processes, experiments on forest covered (Vitexnegundo var. heterophylla) slopes were conducted under various combinations of rainfall intensities and slope gradients. The results showed that litter reduced runoff yield rate by 9–31% and reduced sediment yield rate by 65–90%, with mean runoff and sediment reductions of 18% and 76% for all treatments. On forest covered slopes, Reynolds number and runoff power generally increased with the increase in both rainfall intensity and slope gradient. Litter layer reduced Reynolds number and runoff power with 8–29% and 56–80%, respectively. Darcy–Weisbach resistance coefficient decreased by increasing rainfall intensity and slope gradient. Litter layer increased Darcy–Weisbach resistance coefficient by three to nine times. Relationships between sediment yield rate and Reynolds number, runoff power, Darcy–Weisbach resistance coefficient were described by exponential, linear, power functions, respectively. The critical runoff power values for slopes with and without litter were 0.0027 and 0.0010 m/s, respectively. Reynolds number was the best hydrodynamic parameter for dynamic erosion characterizing.
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Liu, Wen, Qi Feng, Weiping Chen, and Wei Wei. "Assessing the runoff retention of extensive green roofs using runoff coefficients and curve numbers and the impacts of substrate moisture." Hydrology Research 51, no. 4 (July 13, 2020): 635–47. http://dx.doi.org/10.2166/nh.2020.167.
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Abstract In this study, rainfall-runoff data of four green roofs with varying structural configurations under dry and wet substrates were analyzed to acquire the effective estimation for Runoff Coefficient (Cv) and Curve Number (CN) parameters. Results showed that for the dry and wet substrates, averaged runoff retention of vegetated green roofs varied from 34.7 to 48.5% and from 14.7 to 30.6%, that for bare green roofs was 64.9 and 35.1%, respectively. For dry and wet substrates, mean Cv of vegetated green roofs was 0.58 and 0.75, respectively. For vegetated green roofs under the wet substrate, average CN values ranged from 96 to 98, meanwhile for dry substrate, average CN varied from 93 to 97. For bare green roof, average CN was 93 for dry substrate and 97 for wet substrate. Predicted runoff using the SCS-CN method exhibited a good linear fit with the observed runoff of green roofs. A significantly positive relationship was found between initial substrate moisture and runoff coefficient as well as CNs. The drier initial substrate moisture conditions corresponded to the lower runoff coefficient and curve numbers. These results would facilitate the proper use of estimated Cv and CN values of green roofs for urban stormwater management in a semi-arid region.
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Hellebrand, H., L. Hoffmann, J. Juilleret, and L. Pfister. "Assessing winter storm flow generation by means of permeability of the lithology and dominating runoff production processes." Hydrology and Earth System Sciences 11, no. 5 (October 17, 2007): 1673–82. http://dx.doi.org/10.5194/hess-11-1673-2007.
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Abstract. In this study two approaches are used to predict winter storm flow coefficients in meso-scale basins (10 km² to 1000 km²) with a view to regionalization. The winter storm flow coefficient corresponds to the ratio between direct discharge and rainfall. It is basin specific and supposed to give an integrated response to rainfall. The two approaches, which used the permeability of the substratum and dominating runoff generation processes as basin attributes are compared. The study area is the Rhineland Palatinate and the Grand Duchy of Luxembourg and the study focuses on the Nahe basin and its 16 sub-basins (Rhineland Palatinate). For the comparison, three statistical models were derived by means of regression analysis. The models used the winter storm flow coefficient as the dependent variable; the independent variables were the permeability of the substratum, preliminary derived dominating runoff generation processes and a combination of both. It is demonstrated that the permeability and the preliminary derived processes carry different layers of information. Cross-validation and statistical tests were used to determine and evaluate model differences. The cross-validation resulted in a best model performance for the model that used both parameters, followed by the model that used the dominant runoff generation processes. From the statistical tests it was concluded that the models come from different populations, carrying different information layers. Analysis of the residuals of the models indicated that the permeability and runoff generation processes did provide complementary information. Simple linear models appeared to perform well in describing the winter storm flow coefficient at the meso-scale when a combination of the permeability of the substratum and dominating runoff generation processes served as independent parameters.
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Liu, Guangsheng, and Genxu Wang. "Insight into runoff decline due to climate change in China's Water Tower." Water Supply 12, no. 3 (May 1, 2012): 352–61. http://dx.doi.org/10.2166/ws.2012.003.
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Water resources in the Three-Rivers Headwater Region (TRHR), ‘China's Water Tower’, have declined in recent years. In particular, the causes and magnitude of declining runoff in the region remain unclear. This study investigated the recent climatic and hydrological trends in the TRHR. We also analyzed the influence of climate change on runoff decline. Meteorological and runoff data on the TRHR since 1961 were used. The results showed that ‘China's Water Tower’ is threatened by climate changes in several ways. The strong warming trend was the main driving factor for runoff decline. Moreover, the earlier thawing of snow and ice on frozen soil led to a significant decline in May runoff. The descending trend of the runoff coefficient suggests that basin storage and the mechanism of runoff generation may have changed appreciably. Climate warming has also caused recent degradation in the alpine wetland ecosystem and a considerable reduction in the runoff coefficient, thereby inducing a decreasing trend in river runoff. A common understanding of runoff decline due to climate change can be used in the planning and management for social, economic and cultural systems in China and surrounding countries.
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Lupakov, S. Yu. "Estimation of the runoff elasticity of the rivers in the eastern part of the Amur River basin." Geosystems of Transition Zones 5, no. 2 (2021): 179–88. http://dx.doi.org/10.30730/gtrz.2021.5.2.179-188.
Full textAbstract:
Taking into account the unstable moisture regime and the diversity of landscapes within the Amur River basin, the problem of assessing the impact of climatic changes on the processes of surface water cycle in the region becomes multifaceted, associated with the solution of particular problems. This work studied the reaction of a river runoff to changes in the amount of atmospheric precipitation on the basis of the elasticity coefficient. Small and medium-sized river basins (52 in total) belonging to the system of the Middle and Lower Amur are the objects of this study. The data of standard observations at hydrological posts and meteorological points for the summer-autumn flood hazard period (June-September) were used. The data series were selected to include different moisture conditions. It was found that with an increase in precipitation by 1 %, the river runoff in the flood hazard season has increased by 1.02–3.86 % in 48 cases, and decreased in 4 cases. The results of the work are fundamentally close to the regional estimates within the basin of the Amur River on the base of the analysis of factual material (including the near abroad) and simulation results, as well as to the values of the runoff elasticity coefficient obtained in different geographic zones and given in the specialized literature. The relationship between the elasticity coefficient values of runoff with various basin indicators has been studied. For the rivers in the Primorsky Kray (catchment area of the Ussuri River), the relationship between the elasticity coefficient values and the seasonal runoff and precipitation, the runoff coefficient, average height, catchments slopes and average river network slopes has been revealed. The influence of local conditions of runoff formation on the river basins response to changes in the amount of atmospheric precipitation is discussed.
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Wu, Pan, Sihai Liang, Xu-Sheng Wang, Jeffrey M. McKenzie, and Yuqing Feng. "Climate Change Impacts on Cold Season Runoff in the Headwaters of the Yellow River Considering Frozen Ground Degradation." Water 12, no. 2 (February 22, 2020): 602. http://dx.doi.org/10.3390/w12020602.
Full textAbstract:
Climate change has effects on hydrological change in multiple aspects, particularly in the headwaters of the Yellow River (HWYR), which is widely covered by climate-sensitive frozen ground. In this study, the annual runoff was partitioned into four runoff compositions: winter baseflow, snowmelt runoff, rainy season runoff, and recession flow. In addition, the effects of global warming, precipitation change, and frozen ground degradation were considered in long-term variation analyses of the runoff compositions. The moving t-test was employed to detect change points of the hydrometeorological data series from 1961 to 2013, and flow duration curves were used to analyze daily runoff regime change in different periods. It was found that the abrupt change points of cold season runoff, such as recession flow, winter baseflow, and snowmelt runoff, are different from that of the rainy season runoff. The increase in winter baseflow and decrease in snowmelt runoff at the end of 1990s was closely related to global warming. In the 21st century, winter baseflow presented a larger relative increase compared to rainy season runoff. The correlation analyses indicate that winter baseflow and snowmelt runoff are mainly controlled by water-resource-related factors, such as rainy season runoff and the accumulated precipitation in cold season. To analyze the global warming impacts, two runoff coefficients—winter baseflow discharge rate (Rw) and direct snowmelt runoff coefficients (Rs)—were proposed, and their correlation with freezing–thawing indices were analyzed. The increase of Rw is related to the increase in the air temperature thawing index (DDT), but Rs is mainly controlled by the air temperature freezing index (DDF). Meanwhile, the direct snowmelt runoff coefficient (Rs) is significantly and positively correlated to DDF and has decreased at a rate of 0.0011/year since 1980. Under global warming, the direct snowmelt runoff (runoff increment between March to May) of the HWYR could decrease continuously in the future due to the decrease of accumulative snow in cold season and frozen ground degradation. This study provides a better understanding of the long-term runoff characteristic changes in the HWYR.