scholarly journals An empirical approach for computing surface runoff concentration time

2018 ◽  
Vol 9 (2) ◽  
pp. 410-420
Author(s):  
Shanshan Bao ◽  
Xiaojun Wang ◽  
Hongyan Li ◽  
Hang Lv ◽  
Yuening Li
Keyword(s):  
Genetic Algorithm ◽  
Surface Runoff ◽  
Empirical Formula ◽  
Rainfall Intensity ◽  
Daily Precipitation ◽  
Average Concentration ◽  
Songhua River ◽  
Concentration Time ◽  
Average Rainfall ◽  
Basin Area

Abstract This article examines data from the Shihuiyao, Nierji, Tongmeng, Jiangqiao, and Dalai hydrological stations in the Nen River basin to understand the hydrological processes occurring in the catchments. Daily precipitation and runoff data from 1955 to 1973 were combined using the smoothed minima trial method to determine the surface runoff concentration time. Then, a genetic algorithm was used to optimize the parameters and obtain an optimal empirical formula. An improved empirical formula was implemented with the genetic algorithm and optimized parameters then incorporated variable average rainfall intensity, correlation between basin area, surface runoff average concentration time, and average rainfall intensity. Finally, an optimized empirical formula (using genetic algorithm to optimize the parameters) and improved empirical formula (incorporating variable average rainfall intensity) were tested by using the daily precipitation and runoff data from the Baishan and Hongshi hydrological stations of the Second Songhua River. The results show that an optimized and improved formula can be used to more accurately estimate hydrologic conditions in the Nen River. Therefore, the improved formula is an efficient method for calculating surface runoff concentration time. Surface runoff concentration time is an important basis for differentiating source waters, which include surface runoff and underground runoff.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

scholarly journals Development of Temporal Rainfall Pattern for Southern Region of Sarawak

2012 ◽  
Vol 3 ◽  
pp. 17-23 ◽  
Author(s):  
Rosmina A. Bustami ◽  
Nor Azalina Rosli ◽  
Jethro Henry Adam ◽  
Kuan Pei Li
Keyword(s):  
Temporal Pattern ◽  
Rainfall Intensity ◽  
Peninsular Malaysia ◽  
Southern Region ◽  
Rainfall Pattern ◽  
Rainfall Duration ◽  
Design Rainfall ◽  
Average Rainfall ◽  
Urban Storm ◽  
Australian Rainfall

 In the process of a design rainfall, information on rainfall duration, average rainfall intensity and temporal rainfall pattern is important. This study focuses on developing a temporal rainfall pattern for the Southern region of Sarawak since temporal pattern for Sarawak is yet to be available in the Malaysian Urban Storm Water Management Manual (MSMA), which publishes temporal pattern for design storms only for Peninsular Malaysia. The recommended technique by the Australian Rainfall and Runoff (AR&R) known as the ‘Average Variability Method’ and method in Hydrological Procedure No.1-1982 are used to derive design rainfall temporal pattern for the study. Rainfall data of 5 minutes interval from year 1998 to year 2006 for 7 selected rainfall stations in the selected region is obtained from Department of Irrigation and Drainage (DID). The temporal rainfall patterns developed are for 10 minutes,15 minutes, 30 minutes, 60 minutes, 120 minutes, 180 minutes and 360 minutes duration. The results show that Southern region of Sarawak has an exclusive rainfall pattern, which is different from the pattern developed for Peninsular Malaysia.

scholarly journals Study on Variation of Surface Runoff and Soil Moisture Content in the Subgrade of Permeable Pavement Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lijun Hou ◽  
Yuan Wang ◽  
Fengchun Shen ◽  
Ming Lei ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Soil Moisture Content ◽  
Asphalt Pavement ◽  
Infiltration Rate ◽  
Runoff Coefficient ◽  
Flood Peak

The self-designed indoor simulated rainfall device was used to rain on five types of pavement structures with 4 types of rainfall intensity (2.5 mm/min, 3.4 mm/min, 4.6 mm/min, and 5.5 mm/min). The effect of rainfall intensity on the surface runoff, the relation between the subgrade soil moisture content changes, and the influence of initial soil water content on rain infiltration rate are studied. The test results show that the surface runoff coefficient of densely asphalted pavement is greater than 90% in drainage pavements and it has little influence on the reducing and hysteresis of the flood peak. The surface runoff coefficient of large-void asphalt pavement (permeable) is less than 40%. Although the large-void asphalt pavement (permeable) can reduce a small amount of surface runoff, it has no obvious effect on the reduction and hysteresis of the flood peak. In semipermeable pavement, with the increasing of the thickness of base (graded gravel), the surface runoff coefficient decreases at different rainfall intensities, parts of the surface runoff are reduced, and the arrival of flood peaks is delayed. In permeable roads, almost no surface runoff occurred. As time continued, the soil moisture content quickly reached a saturated state and presented a stable infiltration situation under the action of gravity and the gradient of soil water suction. As the initial moisture content increases, the initial infiltration rate decreases and the time to reach a stable infiltration rate becomes shorter. The drier the soil, the greater the initial infiltration rate and the higher the soil moisture content after infiltration stabilization. Permeable roads can greatly alleviate the pressure of urban drainage and reduce the risk of storms and floods.

An Experimental Study on the Rainfall-Runoff Progress of Wheat under Different Slope Angle

2014 ◽  
Vol 912-914 ◽  
pp. 1986-1994
Author(s):  
Na Na Zhao ◽  
Fu Liang Yu ◽  
Chuan Zhe Li ◽  
Jia Liu ◽  
Hao Wang
Keyword(s):  
Regression Analysis ◽  
Soil Moisture ◽  
Power Function ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Slope Angle ◽  
Subsurface Flow ◽  
Rainfall Runoff ◽  
Determination Coefficient ◽  
Initial Soil

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.

scholarly journals Karst bare slope soil erosion and soil quality: a simulation case study

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 985-995 ◽  
Author(s):  
Q. Dai ◽  
Z. Liu ◽  
H. Shao ◽  
Z. Yang
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Soil Infiltration ◽  
Seepage Rate ◽  
Rainfall Duration ◽  
Sediment Production ◽  
Correlation Degree ◽  
Slope Runoff

Abstract. The influence on soil erosion by different bedrock bareness ratios, different rainfall intensities, different underground pore fissure degrees and rainfall duration are researched through manual simulation of microrelief characteristics of karst bare slopes and underground karst crack construction in combination with artificial simulation of rainfall experiment. The results show that firstly, when the rainfall intensity is small (30 and 50 mm h−1), no bottom load loss is produced on the surface, and surface runoff, underground runoff and sediment production are increased with the increasing of rainfall intensity. Secondly, surface runoff and sediment production reduced with increased underground pore fissure degree, while underground runoff and sediment production increased. Thirdly, raindrops hit the surface, forming a crust with rainfall duration. The formation of crusts increases surface runoff erosion and reduces soil infiltration rate. This formation also increases surface-runoff-erosion-damaged crust and increased soil seepage rate. Raindrops continued to hit the surface, leading the formation of crust. Soil permeability showed volatility which was from reduction to increases, reduction, and so on. Surface and subsurface runoff were volatile with rainfall duration. Fourthly, when rock bareness ratio is 50 % and rainfall intensities are 30 and 50 mm h−1, runoff is not produced on the surface, and the slope runoff and sediment production present a fluctuating change with increased rock bareness ratio. Fifthly, the correlation degree between the slope runoff and sediment production and all factors are as follows: rainfall intensity-rainfall duration-underground pore fissure degree–bedrock bareness ratio.

scholarly journals Intellectual productivity under task ambient lighting

2016 ◽  
Vol 50 (2) ◽  
pp. 237-252 ◽  
Author(s):  
H Ishii ◽  
H Kanagawa ◽  
Y Shimamura ◽  
K Uchiyama ◽  
K Miyagi ◽  
...  
Keyword(s):  
Objective Evaluation ◽  
Average Concentration ◽  
Cognitive Tasks ◽  
Colour Temperature ◽  
Time Ratio ◽  
Lighting Conditions ◽  
Concentration Time ◽  
Ambient Lighting ◽  
Normal Colour ◽  
Intellectual Productivity

An experiment was conducted to evaluate intellectual productivity in three lighting conditions: (a) conventional ambient lighting, (b) task ambient lighting with normal colour temperature (5000 K) and (c) task ambient lighting with high colour temperature (6200 K). In the experiment, cognitive tasks were given to 24 participants. The concentration time ratio, which is a quantitative and objective evaluation index of the degree of concentration, was measured. The results showed that the average concentration time ratio under the task ambient lighting with high colour temperature was 72.5%, which was 5.0% points higher than that under the conventional ambient lighting. It is believed that intellectual work can be performed better when the concentration time ratio is high.

Kinneret watershed analysis tool: a cell-based decision tree model for watershed flowand pollutants predictions

2006 ◽  
Vol 53 (10) ◽  
pp. 29-35 ◽  
Author(s):  
A. Preis ◽  
A. Tubaltzev ◽  
A. Ostfeld
Keyword(s):  
Genetic Algorithm ◽  
Lake Kinneret ◽  
Analysis Tool ◽  
Rainfall Time Series ◽  
Tree Model ◽  
Watershed Analysis ◽  
Average Rainfall ◽  
A Cell ◽  
Surface Water Resource ◽  
Series Intensity

This paper presents the methodology and application underlying the Kinneret Watershed Analysis Tool (KWAT), developed for flow and contaminant predictions for Lake Kinneret (the Sea of Galilee) watershed located in northern Israel. Lake Kinneret watershed is about 2,730 km2 (2,070 in Israel, the rest in Lebanon), inhabited by about 200,000 people organized in 25 municipalities, and three cities (the Israeli part). The model aims to predict flow and contaminant transports within the watershed, down to its outlet – Lake Kinneret, the most important surface water resource in Israel. The model is comprised of two sections: quantity and quality. The objective of the quantity section is to tune the values of a vector of coefficients α that multiply the average rainfall time series intensity I(t) (the input) imposed on given sub-sets (i.e., cells) of the basin so as to calibrate their outlet flows Q(t); the quality section then uses these optimal flows Q(t) and the effective optimal rainfall intensities to adjust the values of a vector of coefficients β so as to calibrate the sub-watersheds outlet concentrations C(t). The model uses decision trees coupled with a genetic algorithm for optimally tuning the KWAT coefficients for each of the watershed cells, which taken together comprise the flow and contamination amounts measured at the watershed outlet.

The use of simulated rainfall to study the discharge process and the influence factors of urban surface runoff pollution loads

2015 ◽  
Vol 72 (3) ◽  
pp. 484-490 ◽  
Author(s):  
Li Qinqin ◽  
Chen Qiao ◽  
Deng Jiancai ◽  
Hu Weiping
Keyword(s):  
Surface Runoff ◽  
Rainfall Intensity ◽  
Influence Factors ◽  
Early Period ◽  
Urban Surface ◽  
Discharge Process ◽  
Simulated Rainfall ◽  
Surface Dust ◽  
Pollution Loads ◽  
Runoff Pollution

An understanding of the characteristics of pollutants on impervious surfaces is essential to estimate pollution loads and to design methods to minimize the impacts of pollutants on the environment. In this study, simulated rainfall equipment was constructed to investigate the pollutant discharge process and the influence factors of urban surface runoff (USR). The results indicated that concentrations of total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) appeared to be higher in the early period and then decreased gradually with rainfall duration until finally stabilized. The capacity and particle size of surface dust, rainfall intensity and urban surface slopes affected runoff pollution loads to a variable extent. The loads of TP, TN and COD showed a positive relationship with the surface dust capacity, whereas the maximum TSS load appeared when the surface dust was 0.0317 g·cm−2. Smaller particle sizes (<0.125 mm) of surface dust generated high TN, TP and COD loads. Increases in rainfall intensity and surface slope enhanced the pollution carrying capacity of runoff, leading to higher pollution loads. Knowledge of the influence factors could assist in the management of USR pollution loads.

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