Dissertations / Theses on the topic 'Coefficient of runoff'

Turkey has very different geomorphologic, hydrologic and climatic conditions, so the runoff coefficient should be different from one basin to another. But only one constant value, which is 0.37, is being used for all the basins in Turkey. In this thesis, monthly, seasonal and annual runoff coefficients of 48 sub-basins in western and southern part of Anatolia are determined by using synchronous and average rainfall, runoff data of 26 year record period. Their temporal and spatial distributions are investigated. The relationship between the basin parameters and the runoff coefficient are also examined. Some of the basins have unrealistic large runoff coefficients, therefore excluded from the analyses. The basin boundaries and parameters are determined by using Geograhic Information System (GIS), and areal average precipitations are found by a program written in visual basic language that uses ArcObjects. The Box-Cox transformed data are used in regression analysis. There are a number of dams in the region, which affect the natural flow. Such streams are found and their sub-basins are not used in the analyses. The results revealed that there is not a strong the relationship between the basin parameters and annual and seasonal runoff coefficients for the whole region, but there are significant relations between them for some basins.

Roads and parking lots make up the largest percentage of manmade impervious surfaces in the world. Large amounts of runoff contribute to wastewater treatment plant overloads and subsequent raw sewage discharges. A high runoff rate reduces the groundwater recharge potential, causes stream bed erosion, and flooding which frequently results in the loss of life, property and /or crop damage. High runoff rates also cause surface pollutants to be washed into storm sewers, streams and other waterways, causing damage to aquatic plant and animal life. Pourous pavements are one of the tools which environmental engineers, landscape architects and planners may use in design for stormwater management to help reduce runoff.Previous investigators have assumed that compressed concrete block unit pavements, on a sand bed and gravel base, with sand joints, become impermeable over time. This study sought to determine the runoff coefficient for a trafficked pavement that has been in use for ten months. A Variable Intensity Portable Rain Simulator was used in 120 tests on nine plots from a pedestrian plaza and three plots from an intersection of a neighborhood outlet and a city street, paved with Unidecor (or Cobble-) Pavers. Three rainfall intensity ranges were tested for each pavement type; 0 to 7 millimeters per hour, 7 to 15 millimeters per hour, and 15 to 30 millimeters per hour. For storms with an intensity level of twelve millimeters per hour average, the runoff coefficient on the plaza was significantly different than that for the intersection. Additionally, it was found that for the three intensity ranges tested the runoff was significantly different for each range.Ball State UniversityMuncie, IN 47306

This study examined nonpoint source pollution via tributaries to Pineview Reservoir. Since few literature values of export coefficients are available for snowfall-dominated watersheds such as Pineview, locally scaled rates were quantified using an upstream-downstream bracketing technique. Nitrogen and phosphorus grab samples were manually collected and discharge measurements were conducted during the annual study period. Additionally, high-frequency monitoring sensors that measured EC, temperature, turbidity, and water level were deployed at the up- and downstream sites to represent short-duration transport events and to examine watershed processes on a more representative time scale. Daily nutrient loads were estimated from grab samples and flow rates using the Rank- Data (RD) distribution method and, using surrogate relationships for discharge and total phosphorus (TP) concentration from high-frequency sensors, half-hour TP loads were calculated. Short-duration snow melt events were identified by turbidity spikes and increased air temperatures as well as, in some cases, hydrograph peaks. During these events, export coefficients from 0.31 to 0.54 g TP/ha/hr were observed for low and high elevation snow melt events. While losses to ground water were observed for one study reach, the study reach with positive load gains had annual export coefficients of 0.018 g TP/ha/hr from high-frequency loads and 7.5e-5 g NOx-N/ha/hr, 3.5e-6 g SRP/ha/hr, and 9.1e-6 g TP/ha/hr from RD loads. These rates were 1,000 to 2,000 times greater than available literature values typical of rainfall-dominated watersheds. This study showed the importance of erosive, snow melt events on nutrient transport and the need for high-frequency monitoring representing short-duration events for accurate estimation of export coefficients. Management strategies to reduce nutrients from tributaries should focus on erosion control in the Pineview Reservoir watershed.

Sveriges avloppsledningsnät förnyas och utvidgas kontinuerligt. Idag finns ett flertal datorprogram för hydraulisk modellering av flöden och uppdämningsnivåer i spill- och dagvattennät. Modellerna kan även användas som planeringsverktyg för att bedöma effekter av planerade åtgärder samt för uppföljning av utförda åtgärder. Vid uppbyggnaden av en modell krävs beräkningsresultat från en hydrologisk avrinningsmodell som indata. Det största arbetet vid modelluppbyggandet ligger just i beskrivningen av hydrologin. För att kunna simulera avrinningsförlopp i samband med nederbörd på ett verklighetsliknande sätt är kännedom om storleken på och fördelningen av anslutna hårdgjorda ytor till ledningsnätet med snabb nederbördsavrinning väsentligt. 

 

Till kalibreringen och valideringen av avloppsmodellen krävs mätdata. Flödesmätningar är dyra att genomföra vilket har skapat ett intresse att hitta metoder som säkert beräknar de anslutna hårdgjorda ytorna redan från de uppgifter som finns på kartor och i databaser. Svenska riktlinjer för beräkning av hårdgjorda ytor tillhandahålls av branschorganisationen Svenskt Vatten som företräder VA-verken och VA-bolagen i Sverige. Beräkningar med dessa riktlinjer ger dock inte alltid den korrekta storleken på de hårdgjorda ytorna. Syftet med examensarbetet har varit att undersöka olika metoder att beräkna anslutna hårdgjorda ytor till spillvattennätet samt att undersöka huruvida det finns ett samband mellan de avrinningsområden där beräkningarna av de hårdgjorda ytorna inte stämmer. Nio befintliga modeller framtagna i modelleringsverktyget MIKE URBAN användes vid undersökningen. Sex av dessa modeller användes till kalibrering och tre modeller användes till validering.

 

Undersökningen visade inget samband mellan ytavrinning (reduktionsfaktor) och lutning. Fördelningen av mätpunkter mellan olika jordartskategorier var väldigt ojämn vilket gjorde det svårt att studera huruvida det finns ett samband mellan avrinning och jordart. Resultatet från undersökningen visar att avrinningskoefficienter bör delas upp efter typ av ledningsnät i avrinningsområdet. Metoden med olika avrinningskoefficienter för olika typer av ytor visar på bra resultat för tätbebyggda områden. Metoden med sammanvägda avrinningskoefficienter för olika bebyggelsetyper visar relativt bra resultat med tanke på att det är en överslagsberäkningsmetod.

 

För tätbebyggda områden bedöms metoden med avrinningskoefficienter för olika typer av ytor fungera bra. Vid mindre tätbebyggda områden ökar osäkerheten. Metoden med sammanvägda avrinningskoefficienter för olika bebyggelsetyper bedöms fungera väl för överslagsberäkningar då den är mindre tidskrävande än den andra metoden. Ingen av de undersökta metoderna bedöms kunna ersätta flödesmätningar. 

Sweden’s sewage systems are continuously being maintained and expanded. Several computer programs are today available for hydraulic modeling in sewage and storm water systems. The models can also be used as a planning tool to evaluate effects of planned interventions and to follow up performed interventions. Input data from a runoff model is required at the model build-up. Most of the work in model build-up lies at the description of the hydrology. In order to simulate runoff processes in connection with precipitation, understanding of the size and distribution of impervious surfaces with fast response runoff are essential.

 

Measurements are required for the calibration and validity check of the model. Unfortunately, flow measurements are expensive to perform. This has created an interest to find methods that safely calculate the connected impervious surfaces already from the information that can be found in maps and in databases. The Swedish guidelines for calculation of impervious surfaces are provided by the Swedish Water and Wastewater Association. Calculations with these guidelines do not always give the true size of the impervious surfaces. The aim of this master thesis was to examine various methods to calculate impervious surfaces connected to the sewage system and whether there is a correlation between drainage areas where the calculations do not agree. Nine existing models developed in the computer program MIKE URBAN were used in this study. Six of these models were used in the calibration and three models were used in the validity check of the methods.

 

The study did not show any correlation between runoff (reduction factor) and slope. The distribution of datum points between different soil types varied so much that it made it difficult to study whether there was correlation between runoff and soil type. The result from the study showed that the runoff coefficients should be divided after type of sewage system in the drainage area. The method with runoff coefficients for different types of surfaces showed fairly good results for highly urbanized areas. The method with weighted runoff coefficients for different types of habitations showed relatively good results considering that it is a method for rough calculations.

 

The method with runoff coefficients for different types of surfaces is considered well-functioning for highly urbanized areas. In less urbanized areas, this method showed shorter results. The method with weighted runoff coefficients for different types of habitations is considered well for rough calculations when it is less time consuming than the other method. None of the examined methods are considered able to replace flow measurements.

At the large watershed scale, we emphasize the effects of flow through a river network on streamflow under dry conditions. An immediate consequence of assuming dry conditions is that evapotranspiration causes flow in the river network to exhibit oscillations. When all links in the river network combine their flow patterns, the oscillations interact in ways that change the timing and amplitude of the streamflow waves at the watershed outlet. The geometric shape of the river network is particularly important, so we develop an analytic solution for streamflow which emphasizes that importance. Doing hydrology backward is a strategy recently developed by several researchers to deal with uncertainty in measurements of forcing terms applied to hydrologic models. The strategy has also been applied to resolve the assumption of homogeneity on realistic catchments that exhibit many heterogeneous properties. In this work, we demonstrate hydrology in the backward direction applied to two examples: using streamflow at the catchment scale to determine runoff at the hillslope scale and using the hillslope runoff to infer the applied evapotranspiration forcing under the assumption of dry conditions. In order to work across scales, we utilize the analytic solution for streamflow at the outlet of a river network. At the hillslope scale, we develop a soil model to create fluxes consistent with observed soil processes.

Previous field demonstration projects in metro-Atlanta have shown that seep berms, which are elongated sedimentation basins at the outlet of a disturbed land area, can provide high suspended sediment trap efficiencies with respect to coarse sediments on construction sites having drainage areas greater than five acres. Previous literature has shown that vegetative filter strips are efficient traps for fine suspended sediment in stormwater runoff. A combination of a seep berm and vegetative filter in series was studied in this thesis as an erosion control measure with quantification of its flow resistance and sediment removal efficiency. First, a field demonstration project was implemented to evaluate seep berms as a viable erosion control measure through a side-by-side comparison with the more commonly-used silt fences on construction sites with drainage areas less than five acres in metro Atlanta. High suspended sediment trap efficiencies were recorded for the seep berm on two separate sites, and the seep berm was shown to be superior to silt fences with respect to sediment control in the site runoff. Then a vegetative filter was studied in the laboratory in a specially-built flume for that purpose. The relationship between vegetative drag coefficient and various parameters reflecting flow conditions and vegetation density in steady, uniform open channel flow was studied in the flume. Both rigid, emergent vegetation and submerged, flexible vegetation were studied at two different plant densities. The application of porous media flow concepts to open channel flow through vegetation resulted in a collapse of data for vegetative drag coefficient for the various vegetation types and densities into a single relationship when plotted against vegetative stem Reynolds number. Point velocity and turbulence intensity profiles at different locations in the vegetative filter were recorded with an acoustic Doppler velocimeter to observe the turbulence structure of the flow and its effects on vegetative drag and settling of sediment. A sediment slurry consisting of a suspension of fine sand was fed into the flume, and an automated sampler was used to measure suspended sediment concentrations along the vegetative filter length for a series of discharges from which sediment flux and trap efficiency could be determined. Experimental data for trap efficiency were plotted against a dimensionless settling efficiency for each type of vegetation and density. These relationships, along with the one developed for the coefficient of drag, were applied in a numerical design technique that allows designers to determine the flow depth, velocity and trap efficiency of a vegetative filter of known dimensions for a given flow rate, sediment grain size distribution, slope, and vegetation density. In a typical design example, the combined trap efficiency proved that a seep berm followed by a vegetative filter can be a very effective erosion control measure.

This dissertation is focused to modeling of the rainfall in laboratory conditions by the rainfall simulator invented in VUT Brno. Results of the measuring are compared with measured values of the original rainfall simulator located in VVU VSH VUT in Brno by the Kninicky village in 1976-1980. Dissertation verifies rightness of substituting the natural rain with the rainfall simulator on bare soil in the original location, kinetic energy of the rain drops is substituted with the energy gained from the weight of the drops - the flow. Generally the dissertation determines the possibilities of the rainfall simulator's current location.

碩士
淡江大學
水資源及環境工程學系碩士班
96
This research had collected the daily runoff and daily rainfall data of five different watersheds, which are Chung-Techou watershed, A-Lien-2 watershed, Nan-AO-Chao watershed, Ao-Wei-Chiao watershed, and Hsueh-Shan-Keng watershed, from 1997 to 2006. These data also explains the way of reasoning the time of concentration and runoff coefficient in different watersheds. The rational formula was discussed the relationship between rainfall and runoff coefficient. The data is divided into 5 types, which are one year, November to April, May to October, May to July, August to October, November to January, and February to April. This research makes use of Geographic Information Systems to analyze the effects of the degree of development and slope of each watershed. The relationships between different watershed’s slope, time of concentration and rainfall intensities were also discussed. This preliminary research inquired into the statistical characteristics from the actual measurements in the historical flood, and summed up the influences of the geographically characteristics of five different watersheds. From the analyses’ results, the time of concentration was not directly proportional to the degree of slope. The texture of soil and the type of land use in different watershed area were also examined and analyzed in order to find out how these factors have affected on the surface runoff and the river discharge. The result shows how the influence of land uses and the slope on runoff coefficient in different watersheds. This research suggests that the use of Geographic Information Systems to investigate the watershed environment is essential in the future. Owing to the relationship between nature environment and land exploitation are complicated, it could have great differences according to the various characteristics for different districts. Therefore in the future with similar research, the model (watersheds) should be carefully chosen.

碩士
國立中興大學
土木工程學系
86
In general, runoff coefficient plays an important role in watershed hydrologic designs and managements. Therefore, to systematically determine individual watershed runoff coefficient is quite necessary. This study is thus to combine GIS and rational formula to establish a runoff coefficient distribution map over Taiwan area. Firstly, the entire Taiwan island is divided into three major areas according their geomorphologic and hydrologic properties, the related physiographic factors such as watershed area, slope, stream length ---, etc., can all be generated through GIS software ARC/INFO and ArcView analyses. As for the estimation of watershed design peak flow rates, multi-regression method is used to obtain the 100-year frequency design peak flow rate from the above physiographic independent variables. The results shows the hydrogeneity for the watersheds selected in each area and proves the zonal distributed properties in Taiwan area. On the other hand, rainfall intensity and time of concentration for individual watershed can be solved simultaneously through kinematic-wave governing equations and rainfall-duration formula. These parameters are then fitted into rational formula, runoff coefficients can be obtained and the associated distribution map can then be produced. In summary, the runoff coefficients distribution over the island declines from both east and west coast toward inland mountain areas. In central mountainous area, the values are in closed ring forms with the range 0.55-0.7.The outer value of runoff coefficients in the plain area is 0.8 and it can be considered as an upper value of watershed mountain zones.Also, the general framework of this study is constructed on ArcView GIS software. Since ArcView software employs AVENUE object-oriented programming, the proposed method also contains a group of user interfaces to automatically, user-friendly calculate the outcomes of watersheddesign peak flow rate, time of concentration, rainfall intensity as well as runoff coefficients.

碩士
淡江大學
水資源及環境工程學系碩士班
96
Thesis studies used the measured river discharges and rainfalls from different watersheds for different typhoons and rainfall events. The Rational Formula is analyzed the relation between runoff coefficient and runoff . GIS is calculated slopes and landuses in different watersheds. Compared between concentration times, rainfall intensity, slopes, and landuses, and we analyzed the relation between landuses and the runoff coefficient. It collected the daily runoff and rainfall data from five different watersheds from 1997 to 2006, and the five different typhoons’ data which are Amber, Toraji, Mindulle, HaiTang, and Talim had also been gathered. And it calculated the time of concentration, the rainfall intensity, and runoff coefficient in different watersheds, and it analyzed the relation between runoff coefficient and runoff. From the results, we known that in the rainfall events shown the better agreement in the linear regression analysis. In GIS application on DTM, three type of slope, Ⅰ(0%~5%), Ⅱ(5%~40%), and Ⅲ(＞40%), were use to study the slope effects on the relation between river discharge and surface runoff. From the analyses’ results, the time of concentration was directly proportional to the degree of slope. According to different landuses, we discussed the relation between the degree of the developmens and runoff coefficients. The results of this research showed, besides Ma-An-Chi Bridge and Ma-Yeuan Bridge, landuses were better and run-off coefficient were better in the typhoon events.In the effective rainfall''s events, landuses were better and run-off coefficient were better in all watersheds.

碩士
國立臺灣大學
農業工程學系
82
At present, only the total runoff coefficient data for the Meinung Basin si available in Taiwan. Runoff coefficient data based on various land uses are not yet available because of its very small drainage area. In order to obtain more economic cross-section in the design of drainage canals and structures in that basin, more accurate calculation of drainage discharge is indispensable. In this study, rainfall coefficients of the respective small drainage areas in Meinung basin are estimated by using correction/revision method. Runoff coefficient values form outside area were first adopted for calculation and analysis by substituting various land use data of the respective small drainage areas and taking account of the drainage discharge diverted by Chu-Tze-Men Hydropower Plant. Then a correction value, k, can be calculated. After substituting these K- values into the original equation, corrected runoff coefficients for the respective small drainage areas with different land uses and frequencies can be obtained. The results of comparing the corrected K-Values for the maximum daily rainfall with various frequency are as follows: (1) When the recurrent period is equal to ot less than two years, K-value is large than one. (2) When the recurrent period is more than two years (i.e., 5, 10..........100 years), K-value is smaller than one and is decreasing with the increment of recurrent period. The average error of the calculated K-value with various frequencies in this study is 0.999, approximately equal to one. This shows that the runoff coefficients derived by Mono Be of Japan can be directly adopted for the Meinung Basin.

碩士
國立中興大學
土木工程學系
92
Runoff coefficient is an important index in analysis and design of Hydrology. It can be used to compare inflow with outflow. The runoff coefficient in common used is an approximate figure and it will be changed with difference of local characteristic. The discharge in a certain region can be calculated if we can get an exact runoff coefficient. Therefore the study combined rainfall intensity data with diffusive Tank Model to calculate the runoff coefficient in a certain region with actual and designed rainfall intensity. Diffusive Tank Model is connected with several tanks that can be used to retain water and the effect of simulation is very well. It has fine beneficial result for the runoff coefficient in this study. A test piece is to be situated at Kaohsiung Daliao. The study is according to paddy fields. At the final chapter, I will put this Runoff coefficient into SCS Curve Number Method established from U.S. Soil Conservation Service to find the Curve Number in this test place and check it with soil texture classification of U.S. Soil Conservation Service to prove the adaptation in Taiwan and analyze the similitude with the two models.

碩士
國立彰化師範大學
地理學系
100
Curve number method which was made by Soil Conservation Service of USA has been a worldwide method for flood estimation, but many scholars have thought that it has some serious problems, including classificational form of antecedent moisture condition and no consideration of characteristics of precipitation. What is above should be explored further in order to increase the correctness of flood estimation. In the thesis, the scope of this area of research is Chichiawan watershed, I use precipitation stations and a stream gauging station from Water Resources Agency, and choose materials of hourly precipitation and hourly stream gauging, which is from 1992 to 2002. Then these materials are carried out under preliminary analysis. In the events of precipitation and runoff of these years, I select the huger storm of one to three in every year, and the total amounts are twenty-one. Then I calculate the value of curve number with the method of base flow separation. In addition, all possible parameters of characteristics of rainfall which affects are calculated, including precipitation, intensity of rainfall and antecedent moisture condition, and coefficient of runoff is figured with the ratio precipitation to runoff volumes. And then, multiple regression analysis is carried out, that is, to analyze the regression between curve number, coefficient of runoff and characteristics of rainfall. After finishing the analysis, in order to reduce the error of the model to the minimum, I use correct estimations, including R2, RMSE and Scatter Diagram. The result of research shows that the effect of antecedent moisture condition is obvious, but curve number should not be separated three grades, and it is a continuous and variable process. Besides, among the characteristics of rainfall, put precipitation, the intensity of rainfall, and the rainfall of antecedent five days into multiple regression analysis, compared with correct estimations, and finally the effects of corelation is great.

碩士
國立中興大學
水土保持學系
88
The slope of hill in Taiwan has being been cultivated and used illegally and so that the disasters have been occurred so frequently result from pouring rain for the bellowing reasons: special geographical location, bad morphological and hydrological condition, the increasing population tension, industrial and economical consisting development and the social continuous change. To avoid and prevent disasters occuring, we must set in order to the watershed systematically and build soil and water conservation project in suitable place. Usually, we estimate the design runoff by Rational formula Q=(1/360)*CIA, and the key of successfully estimation of runoff is runoff coefficient C. This study use the image that was collected from the SPOT satellite, first to proceed image, secondary to analyze, and then use SCS CN approach of U.S. Soil Conservation Service, in order to conduct the situation of land use, the water content of soil, and the density of vegetation covering in the watershed. After combining by GIS, we can find the corresponding SCS curve number in every grid, and runoff coefficient of four seasons in the watershed. We found that the runoff coefficient is very high in summer and fall because of the rainfall those caused in West-South monsoon and typhoon. And in winter, result from the East-North monsoon in north of Taiwan, the runoff coefficient is higher than any other places in Taiwan. The results of this study will be available for people to refer when they will design soil and water conservation engineering constructions and to research on remote sensing hydrology.

碩士
淡江大學
水資源及環境工程學系碩士班
96
This paper discusses and analyzes the relation between runoff and rainfall of watershed area in raining situation. The flow and accumulated rainfall data of Hsiu-Luan headwaters watershed area of Tamshui river basin, Nei-Wan headwaters watershed area of TouChien river, and Pi An Chou headwaters watershed area of HouLong river in these ten years are collected and analyzed. The data includes the average of summation of daily runoff, the average of summation of first half year daily runoff, the average of summation of first 1/3 big daily runoff, and the average of summation of first 1/10 big daily runoff. Rational formula and GIS are used to analyze the relation between runoff coefficient, runoff, and degree of slope. The land use levels are used to determine the relation between developed area and runoff coefficient. The IA coefficient are use to analyze in this paper. The level of Pi An Chou is higher then other two basins. The runoff coefficient is also higher then other two basins.

In this diploma thesis the issue of drainage system influence on water regime of catchment area was solved. The aim of the thesis was to analyze influence of drainage system on specific catchment area using mathematical, hydrological and statistical methods. In the teoretical part, the thesis describes the issue of drainage (specifically the drainage system of area of the Czech republic) and the influence of drainage system on water regime. In the practical part an analysis of the catchment area of Kopaninský creek and subcatchment areas P6, P52 and P53 was performed. At all of those areas, certains parts are dewatered by subsurface systematic drainage system, those parts are described in detail. The runoff coefficients and specific runoff from each subcatchment areas in different time interval were calculated and observed. Runoff separation and precipitation-runoff situation analysis were performed. The results are evaulated in the chapter Results and Discussion.

The thesis is divided into theoretical and practical part. The theoretical part includes issues associated with runoff and discharge, methods for discharge measurement and measurements of uncertainties. The practical part of the thesis describes a specific process flow measurement in Kopaninský and Jenínský stream. There is a familiarization with the water flow velocity measurement and comparison methods of volume measurement discharge with continuous measurement. The results of the practical part served to refine the rainfall-runoff processes in research catchment areas. Refined values of the flow rate were used as input data for the calculation of the runoff coefficient and for quantifying the losses of nutrients from the catchment areas. Calculation of the runoff coefficient and nutrient losses were compared for the original and the revised equation discharge curve. Volume measurement discharge has shown that the different conditions above measurement weir during continuous monitoring lead to the uncertainties of measurement. That´s why one has to approach to each flowmeasurement individually and consider the situation in a particular installation.

碩士
國立中興大學
水土保持學系所
96
The GRAPH (Grid Rational Algorithm for Predicting Hydrograph) model has been developed for rainfall-runoff simulation in recent years. Due to different characteristics in watershed topography and hydrology, and the model neglecting the situation of sediment transportation and antecedent precipitation; the simulation results of the model should be adjusted to fit the real world by means of correction coefficients. Coefficient α represents water resources conservation capability and the coefficient β can be regarded as the index of sediment concentration in the runoff. In this study, simulated data are collected from previous studies for discussing the relationship between grouping the variations of (α，β) and the correspondent watershed topographic factors by using multivariate analysis. Correction coefficients and topographic factors derived from seven watersheds were used in the multivariate analysis. The result shows that twelve topographic factors in four principal axes can explain 90% variability; ten factors with significant correction from eigenvector were further selected for discriminant analysis. Factor of elongation ratio and circularity ratio were deleted due to less discrimination in structure matrix ,there are still remain eight topographic factors (perimeter of watershed, length of main stream, length of watershed, time of concentration, area of watershed, width of watershed, average slope and average initial runoff coefficient) showing significant discrimination.Watershed characteristics through the distribution of correction coefficients describes as follows: (1)Watershed with more function of water cultivation such as Da-Nan-Ao；(2)Watershed vulnerable to landslide during storm period, higher landslide potential such as Wu River, Ba-zhang River and Xin-Wu-Liu River；(3)Watershed with artificial disturbance and the improper land use caused river blockage during storm period such as Keelung River；(4)Watershed with landslide-dammed such as Choshui River；(5)Watershed with mudstone such as Erhjin River. Accuracy rate of correction coefficients variation is 90% which classifies by topographic factors, and the result shows that there is highly correlation between each other. Topographic factors can be a basis of classification for calculating discriminative score.