KR20150034368A

KR20150034368A - Method for Calculating Flood Discharge using Field Infiltration Tests

Info

Publication number: KR20150034368A
Application number: KR20130114355A
Authority: KR
Inventors: 강영복
Original assignee: 강영복
Priority date: 2013-09-26
Filing date: 2013-09-26
Publication date: 2015-04-03

Abstract

The present invention relates to a system and method for estimating flood rate using on-site penetration test, and it is an object of the present invention to provide a system and method for calculating flood amount using on-site penetration test, It is possible to improve the reliability of the flood calculation results compared with the prior art and to apply it to various sites by calculating the flood amount according to the SWMM model and the Clark synthesis unit method.

Description

[0001] Field of the Invention [0002]

The present invention relates to a method for estimating flood discharge using an on-site penetration test, and more particularly, to an on-site penetration test on a watershed to be analyzed, The present invention relates to a method of estimating flood flow using a field penetration test, which can greatly improve the reliability of flood calculation results compared to the prior art and can be applied to various sites by estimating the flood flow according to the SWMM model and the Clark synthesis unit diagram.

Recent rainfall patterns have caused frequent damage due to localized localized heavy rains due to local characteristics, and interest in sudden floods has increased and studies are being carried out to identify and predict the causes of these floods in various areas.

The most preferred effective rainfall calculation method in the conventional water resource practice is a method using a rational formula and a CN (Curve Number) value of a standard rainfall-runoff curve method. Considering the characteristics of domestic terrain, it has considerable problems in terms of application criteria and reliability.

As an example of a conventional technique for estimating the flood discharge amount by estimating the flow amount of the analysis target watershed, Korean Unexamined Patent Application Publication No. 10-2005-0090158, entitled " Method for calculating the runoff amount of the target watershed using the digital map superposition " (CN), which is a hydrological topography factor, and automatically constructs the input data of the runoff model using the digital map to estimate the flood amount.

However, as mentioned above, as described above, since the CN value of the standard rainfall-runoff curve method is applied uniformly without considering the characteristics of the target watershed, the application standard is not clear and the problem of lack of reliability It was the same.

The problem to be solved by the present invention is to overcome the above problems, and it is an object of the present invention to provide a method and apparatus for analyzing the penetration curves of soils and fields, The present invention provides a method of estimating flood amount using on-site penetration test which can greatly improve the reliability of the flood calculation results compared with the prior art and can be applied to various sites by calculating the flood amount according to the SWMM model and the Clark synthesis unit method.

The present invention relates to a method for estimating flood amount using an on-site penetration test, comprising the steps of: (A) selecting a watershed for a site penetration test; (B) conducting a watershed characterization survey in the selected watershed; (C) selecting a site penetration test method; (D) performing field penetration test to obtain actual penetration test data in the target watershed; (E) estimating the effective rainfall in the target watershed according to the SWMM model using actual penetration test data; And (F) calculating a flood amount by applying the Clark synthesis unit method according to the result of calculating the effective rainfall in the target watershed.

At this time, the step (D) includes: (D1) conducting a soil characteristics survey on a watershed; (D2) selecting a site penetration test site; (D3) performing penetration test on the ground to calculate permeability per land use; (D4) inducing the infiltration curves of the soils; And (D5) deriving a penetration curve equation according to the land use status.

Particularly, the soil characteristics survey item according to the step (D1) can be classified into soil pot, base material and sedimentation mode, land use status, land use recommendation, soil drainage status, erosion potential, effective soil surface, The present state of inclusion, the trend of watershed inclination, and the status of the soil of the soil.

Advantageously, the step (E) comprises: (E1) determining a watershed input data comprising an area mean slope of the watershed, an area of the impervious area, a length of the lower and upper walls, a width of the lower or upper waterway, step; And (E2) determining an effective rainfall using the determined watershed input data.

Also preferably, (F) comprises: (F1) determining a parameter; And (F2) estimating the flood discharge amount by analyzing the infiltration ability by the duration of the rainfall using the infiltration curve equation according to the determined parameters.

According to the present invention, there is provided a method of estimating the flood amount using the field penetration test, which can significantly improve the reliability of the flood amount estimation result and apply it to various sites in comparison with the prior art, There is an effect to provide.

Figs. 1a-1k show results of soil characterization for the target watershed.
FIG. 2 is a graph comparing the permeability of the target watershed by land use status.
3 is a graph showing the Clark synthesis unit derivation method.
4 is a graph showing the flood discharge amount according to the effective rainfall calculation method.
FIG. 5 is an overall flowchart of a method for estimating flood amount using a field penetration test according to a preferred embodiment of the present invention. FIG.

Before describing the specific details for the practice of the invention, terms and words used in the specification and claims should be construed to enable the inventor to properly define the concept of a term in order to best describe its invention It should be interpreted as meaning and concept consistent with the technical idea of the present invention.

It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

The present inventors have recognized that it is necessary to clearly calculate the outflow characteristics in consideration of the infiltration amount and the rainfall intensity in order to calculate the flood amount in the analysis watershed. Particularly, the conventional effective rainfall estimation method, The CN (Curve Number) method of the relationship curve method has been recognized as a problem and it has been studied to overcome these problems.

Specifically, the inventors of the present invention derive an effective rainfall criterion based on the relationship between the infiltration curve and the rainfall intensity calculated from actual permeability data according to the actual soil conditions, and based on the result, various conditions such as land use pattern, soil canal, (Huber and Dickinson, 1988) model, NRCS composite unit method, and Clark composite unit method were used to calculate flood discharge.

In addition, the reliability was verified by comparing the flood amount calculated by the effective rain rate calculation with the actual flood amount measured in the actual river. The effective rainfall criterion itself was compared with the Horton penetration curve method and the NRCS method Reliability was verified.

As a statistical processing program for various data calculation and comparison with the measurement results in the present invention, general purpose programs such as Excel and SPSS (Statistical Package for the Social Sciences) were used.

Hereinafter, a method of estimating flood water using a field penetration test according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1A to 5.

FIG. 2 is a graph comparing the infiltration ability of the target watershed by land use status, FIG. 3 is a graph showing a Clark synthesis unit guiding method, and FIG. 4 is a graph showing a flood discharge amount according to an effective rainfall estimation method, and FIG. 5 is a general flowchart of a flood amount estimation method using a field penetration test according to a preferred embodiment of the present invention.

First, select the watershed for the site penetration test ( S11 ).

In the preferred embodiment of the present invention, the Hongcheon River basin was selected as the basin for the field penetration test, the basin area was 880.64 km ² , the Hongcheon River water level observatory was used as the starting point for the flow test and correction, The total watershed area is 955 km ² when it is included in the watershed until the Ochan River merges downstream of Hongcheon Bridge to study.

Next, a watershed characterization survey is conducted on the selected watershed ( S12 ).

In the preferred embodiment of the present invention, the watershed characteristics survey was conducted based on the Hongcheon River Hongcheon Bridge in the target watershed. As described above, the target watershed area was 880.64 km ² , the flow length was 78.7 km, the watershed average width was 11.19 km And the shape coefficient is 0.142.

The slope of slope is 1/799, which is a mild slope. The minimum stream width is 33 m at the most upstream but the width is 100 m ~ 227 m from the starting point to 29 km. The roughness coefficient is 0.030 ~ 0.035 (Gangwon-do, 1990) because there are many gravel and sand in the underground.

The first tributary to be merged at the upstream 22.4 km from Hongcheon Bridge is the local river (54.5 km) and the river basin (342.0 km ² ), which accounts for 38.8% of the basin (Hongcheon, 1994).

The characteristics of the inner watershed in the Hongcheon River are characterized by the extension of the inner watershed stream rather than the upper stream extension of the Hongcheon River, Therefore, determination of inflow time and dwelling time of Hongcheon river, time of occurrence of peak flood amount, and the like were investigated and reflected in the present invention.

Table 1 shows the watershed characteristics of the Hongcheon River and Nunchon River.

Next, the site penetration test method is selected ( S13 ).

In the preferred embodiment of the present invention, the permeability test method uses a standard dual pipe permeability measuring device and a small dual pipe permeability measuring device in parallel. Specifically, in principle, a standard double pipe permeability measuring device is used, A small dual tube permeability meter was used in areas where it is difficult to penetrate more than 10 cm from the ground and where it is difficult to use standard double pipe permeability measuring instruments such as areas where water permeability is high and water needs to be frequently injected into a tube of a standard permeability meter.

On the other hand, as a test method of penetration into the reservoir, it is known that a method suitable for the site condition is performed by referring to the ore-hole (standard type), the bottom penetration method, and the physical test in Korea. In the US, a standard penetration test is performed using a double-ring infiltrometer (ASTM D3385-03).

The standard double tube permeability meter used an outer pipe diameter of 600 mm and an inner pipe diameter of 300 mm. Experiments using this device are known to be less reliable than those with a hydraulic conductivity of greater than 10 ^-2 cm / s or less than 10 ^-6 cm / s, It is inconvenient to experiment in a place where it is not easy to access. In addition, if the water supply for the experiment is not smooth in the area with high permeability, the continuity of the experiment is lost and the experiment itself is impossible.

A small permeability meter was used with an outer tube diameter of 110 mm and an inner tube diameter of 64 mm. According to a study by the US Environmental Protection Agency, a small permeability meter manufactured by Turf-Tec has been suggested to be convenient for use in a variety of soil conditions (Lantrip and Harrison, 1999). Turf-Tec's small permeability tester is smaller than standard double tube permeability tester. Therefore, it is very easy to carry and experiment in areas where water requirement is small and access is difficult.

Next, the site penetration test is performed to obtain the actual penetration test data in the target watershed ( S14 ).

The area to be penetrated is currently undeveloped and the majority of them are inaccessible and there is a need to supply large quantities of water to carry out continuous testing. However, in some areas due to local conditions, it was not easy to supply the necessary water for the experiment. Therefore, in the area where the soil layer is deep in the penetration test area, the installation of the measuring device is good, and the water supply and access is easiest, the standard double pipe permeability measuring device and the small double pipe permeability measuring device are tested in parallel, and the penetration test data Respectively.

Below, S14 The steps will be described in more detail.

(1) Investigate soil characteristics.

As shown in FIGS. 1A to 1K, the soil characteristics survey items were classified into soil type, base material and sedimentation style, land use status, land use recommendation, soil drainage status, Soil, Soil and Gravel, Watershed Slope Status, and Topsoil Saturn Status.

Fig. 1 (a) is a view showing a soil drainage state, Fig. 1 (f) shows an erosion possibility status, Fig. 1 (g) shows an effective soil surface, 1h shows the state of the deep sea soil, FIG. 1I shows the state of the sea surface gravel, FIG. 1J shows the state of the watershed slope, and FIG.

Referring to FIG. 1A, a total of 89 soil pots were classified into 48 soil pots according to the inclination of the terrain. As shown in Fig. 1b, the metamorphic rocks were 65.73% (627.7 km ² ), the igneous rock 27.84% (265.9 km ² ), the sedimentary rock 1.03% (9.8 km ² ) and the fourth base 5.4% km ² ), and organic matter content and water content of soils were classified according to the characteristics of geology.

FIG. 1D shows the land use status in consideration of the soil condition. FIG. 1C shows the land use status. Forest area is 67.85% (644.0 km ² ), grassland (grassland) is 12.15% (115.3 km ^2), before (田) is 11.32% (107.4 km ^2), answer (畓) is 5.88% (55.8 km ^2), the river is ^{2.58% (24.6 km 2),} 0.22% in the following Of which 2.06 km ² is the other land. Next, FIG. 1e shows the drainage of the soil, showing a very good area of 54.50% (520.4 km ² ), a slightly better area of 5.30% (50.6 km ² ), and a slightly better area of 6.67% (350.2 km ² ), and some defects were 0.97% (9.2 km ² ).

Saturn of the topsoil is determined according to Fig. 1h as the erosion-incapable area (Fig. 1f). The effective soil depth of the soil is 8.13% (77.6 km ² ) for 100 cm or more, 33.19% (316.9 km ² ) for 50 cm ~ 100 cm and 36.51% (348.6 km ² ) for 20 cm ~ 50 cm ² ), and below 20cm, 22.18% (211.8 km ² ), which is widely distributed as 53.74% (513.3 km ² ) in areas where surface erosion occurs.

As shown in Fig. 1j, the slope of the watershed corresponds to 67.4% of the area where the slope of the watershed is 60% to 100%, followed by 12.3% of the areas that make up 15% to 60%. Less than 15% corresponds to 14.8%, and the watershed is mostly mountainous and the slope of the watershed is very harsh.

(2) Select site penetration test site.

In a preferred embodiment of the present invention, 29 sites were selected for 18 soil containers occupying a large area in the target watershed of the above-mentioned soil tanks as the site penetration test sites. The number of penetration tests was determined according to the soil container area, and 50 km ² 3 to 4 times, 50 km ² The following points were selected so that one can be done. Thirty-one soil pots with a small area and similar drainage grades and less impact on the watershed runoff were excluded from the penetration test.

The results of the site penetration testing site selection are shown in [Table 2].

(3) The site penetration test was conducted to determine the land By use Infiltration .

As a result of field penetration test, the infiltration capacity varied according to the soil saturation. The average infiltration capacity per land use was 4.109 × 10 ^-2 cm / s, initial infiltration capacity 1.4 × 10 ^-2 cm / s, The initial permeability was 1.451 × 10 ^-3 cm / s and the infiltration capacity was 1.188 × 10 ^-3 cm / s to 10 ^-3 cm / s. The initial permeability was 5.890 × 10 ^-2 cm / s and the infiltration capacity was 1.7 × 10 ^-2 cm / s. The initial permeability was 6.033 × 10 ^-2 cm / s and the infiltration capacity was 1.52 × 10 ^{- 2} cm / s.

Next, the infiltration time was different according to infiltration ability of soils. The site area showed a penetration time of about 60 minutes to the infiltration ability, and the forest area was about 110 minutes and the whole area was less than 200 minutes. In the calculations of infiltration by soils, the infiltration ability of the soils was prepared by regression analysis of the results of field penetration test.

Table 3 shows the results of the infiltration rate and the infiltration ability of the soils.

(4) Sole star Permeability Induce a curvature.

Table 5 shows the results of the infiltration curves of the soils by analyzing the results of field penetration test in the target watershed.

The penetration ability according to the results of field penetration test is measured continuously. When applied to the Horton penetration model, the initial permeability, the infiltration ability and the time are known, so the reduction constant (k) can be determined.

In the present study, it was considered that the permeability of the soil was not significantly different from that of the hydrological soil because the geological characteristics were similar to those of the soil watershed. Therefore, the present invention was applied to the Horton infiltration model It was able to compare with NRCS effective rainfall calculation value.

(5) Derive infiltration curves according to land use status.

The infiltration curves were derived by summarizing the infiltration test results according to the land use status of each land area. Table 6 shows the penetration curves for each field.

As shown in FIG. 2, when the permeability of the forest area is analyzed, it is analyzed that 100% leakage occurs when rainfall of 80 mm / hr or more occurs. In case of rainfall exceeding 20 mm / hr, It was investigated that leakage would occur. When the rainfall intensity is more than 80 mm / hr, the rainfall area is also impermeable and the rainfall occurs.

Next, using actual penetration test data SWMM The effective rainfall in the target watershed is estimated according to the model ( S15 ).

Before describing step S15 in detail, the SWMM model will be described in detail.

SWMM is a model developed by Metcalf and Eddy in 1971 under the auspices of the US EPA to estimate floods caused by rainfall in urban waters. The SWMM is a model developed by Florida University and Water Resources Engineers (WRE) And water quality (Huber and Dickinson, 1988).

SWMM is designed to simulate actual storm events in consideration of system characteristics such as rainfall column, meteorological input data, and subwatersheds and sewer pipelines to predict outflows and water quality due to heavy rainfall. In 1981, the EXTRAN block, which was designed to be able to calculate the overflow, drainage, and pressure flow of the hand structures, was added to the model to supplement the TRANSPORT block in the SWMM model. Finally, the SWMM model is a comprehensive model that can simulate the surface and subsurface flow caused by rainfall events in the urban watershed, trace the runoff to the drainage network, simulate the reservoir, treat the pollutants and calculate the cost.

The SWMM model consists of four execution blocks such as RUNOFF block, TRANSPORT block, EXTRAN block and STORAGE / TREATMENT block, and five sub blocks such as RAIN block, TEMPERATURE block, COMBIN block and STATISTICS block. .

Below, S15 The steps will be described in detail.

end. Determine watershed input data.

Inputs related to the watershed include the area average slope of the watershed, the area of the impervious area, the length of the underpass and pipe network, the width of the pipe or underpass, and the slope of the underpass. Manning coefficients of the water and impervious watersheds, Manning coefficient of the waterway and pipe network, surface storage, penetration related parameters, and characteristic width.

In the present invention, a digital topographic map (1: 25,000) issued by the National Geographic Survey of the Ministry of Land, Transport and Maritime Affairs, a detailed soil map (1: 25,000) provided by the Rural Development Administration,

Digital topographic maps were separated and quantified using AutoCAD. Soil classification and land use status were analyzed using GIS software for precision soil and land use. The construction of river condition was constructed by using HEC-RAS in vertical and horizontal cross-section of Hongcheon River Basic Plan Report and applied to construct river basin model.

Specifically, for subdivision of subwatersheds, as shown in [Table 7], the Hongcheon River Stream Basic Plan NO. 280 Changjeon Pyeongchun Confluence Point (Hongcheon County, 2007) as the end point and 27 upstream subwatersheds.

For river network input data, as shown in [Table 8], 23 river basin models were constructed, natural river shape was applied for a certain period, and the inflow channel and the upstream part were converted into the number channel section.

I. Use the determined watershed input data to calculate the effective rainfall.

The valid rainfall was calculated using SWMM input data, and the calculated results were compared with past results. Especially, from the past survey data of Hongcheon River, The results were compared with the results from August 6 to 7, 2002, July 12 to 18, 2006.

The change of flood discharge by the effective rainfall method was studied. The flow rate of the NRCS effective rainfall calculation method and the Horton method were compared with the measured flow rate (daily mean flow).

The rainfall was calculated by inputting the daily rainfall and determining the runoff interval as 1 hour, and analyzed the change of the runoff amount according to the effective rainfall calculation method.

Based on the schedule of soil penetration testing by soil canal, the number of days of preceding rainfall was measured by the Korea Meteorological Administration (KMA). The model was applied with AMC (Early Soil Function Condition) at 60.3mm / 5 days and the initial penetration test results of the Horton method And 6 - hour time convergence to the infiltration ability and the infiltration ability were applied to all the soils, and the parameters were calculated and analyzed.

Table 9 shows the calculation results and the actual results according to the effective rainfall calculation method at the Hongcheon Bridge Bridge as the effective rainfall using SWMM.

Next, according to the result of the calculation of the effective rainfall in the target watershed Clark The flood quantities are calculated by applying the synthetic unit method ( S16 ).

Before describing step S16 in detail, the Clark synthesis unit method will be described in detail.

The basic concept of the Clark Synthetic Unit Method is to assume that the basin is composed of a linear reservoir located in the linear channel and the outlet of the basin and consider the transition effect of the outflow by the linear channel and the attenuation of the basin by the linear reservoir (Instantaneous Unit Hydrograph, IUH).

The transition effect of the runoff due to the linear waterway is considered by calculating the outflow due to the instantaneous unit effective rainfall, which is the unit effective rainfall momentarily dropped across the watershed, by simple transition using the time-area curve. It becomes the inflow hydrograph of the linear reservoir. The effect of the linear reservoir on the watershed is considered by performing a flood trace of the linear reservoir (S = KO) with the same reservoir characteristics for the influent hydrologic curve. The output of the linear reservoir thus calculated is the instantaneous unit of the watershed . The Clark method is suitable for natural watersheds because it can more accurately estimate the physical phenomena of the actual runoff considering not only the runoff transfer effect but also the reservoir effect.

The procedure for the Clark synthesis unit method is as follows.

A kyu-hashou isochronous line connecting the same flood reach times is used to divide the entire watershed into several subwatersheds and to calculate the time-area columnarity (time -area histogram, TAH).

When the unit effective rainfall instantaneously falls across the whole watershed, the inflow volume per hour interval to the watershed outlet linear reservoir is the unit effective rainfall (1cm) that falls on the area per arrival time interval, The inflow curvature of the inflow curve is calculated by the following equation (1).

In Equation (1), the inflow amount (m ³ s) of the i-th time period is the watershed area (km ² ) included in the i-th time period.

The continuity equation is transformed according to the storage equation (S = KO) according to the assumption of linearity with respect to the relationship between the storage amount and the discharge amount of the linear reservoir located at the outlet of the watershed, as shown in the following equation (2).

When the modified continuity equation is solved for O ₂ , it is summarized as the following equation (3), and the coefficients m ₀ , m ₁ and m ₂ can be calculated by determining the storage constant K and the time interval Δt.

In the case of the time-area columnarity created from the area curve, the time point of the tracing period and the inflow amount of the end point are the same (=) in the application of the continuity equation, the following equation (4) , It is possible to determine the end point of the momentary degree of the watershed outlet point by tracking the inflowing hydrograph by the period of time.

In order to construct the unit diagram of the necessary duration by using the instantaneous unit figure, it is necessary to delay to the right by t time so as to average the time interval end of two IUHs every time, The method of converting the duration of the diagram is mainly applied.

The parameter estimation method is as follows.

The Clark method is a synthetic unit method with the arrival time (concentration time) and the storage constant K as input factors.

The concentration time can be determined by measuring the time from the effective rain edge to the inflection point of the hydrographic curve in the meteorological watershed. In the meteorological watershed, the falling time is calculated using empirical formulas such as Kirpich, Rziha, Kraven formula, shall.

Below, S16 The steps will be described in detail.

a. Determine the parameters.

The Clark Synthetic Unit Method is suitable for natural river basins and is applied to estimate the flood discharge of the watershed in four local rivers, the middle and upper tributaries of the Hongcheon River.

For this purpose, the infiltration curve parameters were determined by the area - weighting method for each station by using the Horton method. In the field penetration test, the amount of previous rainfall was 60.3mm / 5 days, but the soil pots in the mountainous area were highly infiltrative and the permeability was less in the case of agricultural land (answer). The mean depth of effective soil depth was 0.73 m and was analyzed to be between 0.43 m and 1.12 m.

[Table 10] shows applied CN and permeability parameters for each river.

b. Depending on the parameters you decide Permeability Using the curves, spit The flood discharge is estimated by analyzing the penetration.

Horton 's infiltration curves were used to analyze the infiltration capacity by applying the results of field penetration test to the parameters, and the flood discharge was calculated and compared with the NRCS effective rainfall calculation method.

In the NRCS effective rainfall calculation method, the initial loss flow is constantly lost to 20% of the basal flow rate, and a certain amount of total flow is decreased according to the CN value, and the effective rainfall is calculated by the duration of the rainfall. However, when Horton 's infiltration curves are used, it is necessary to generate more rainfall than the infiltration rate, so that the effective rainfall occurs more slowly and the flow rate tends to be smaller than NRCS method.

More specifically, effective rainfall was calculated by applying the NRCS effective rainfall and Horton method, and the infiltration curve parameters were determined by area weighting method for each soil type. When the penetration test was carried out, the condition of the preceding rainfall was 60.4mm for 5 days, but the permeability was higher in the mountain area and the permeability was lower in the agricultural area (answer), and the soil condition was calculated assuming the natural condition. The CN values were calculated by hydrologic soil classification and were 40.97, 62.15, and 78.99 under AMC conditions (I, II, and III), respectively.

As shown in Table 11, the effective rainfall by the Horton infiltration curves was calculated from the AMC (221.0 mm / 12) of the NRCS, hr) and 186.9 mm / 12 hr, which is smaller than the AMC-Ⅲ (286.9 mm / 12 hr) condition of the NRCS, which is generally applied in practice.

If the effective rainfall is large, the flow rate flowing out of the concept of total amount should be concentrated within the rainfall time. However, the actual water level of the Hongcheon River has been maintained for a certain period after the end of rainfall. This means that the subsurface runoff flows through the upper layer of the soil layer after the precipitation penetrates into the surface layer, and a part of the base flow rate of 84 ~ flows into the river.

In terms of effective rainfall runoff, the NRCS method shows runoff from the beginning of rainfall, but the infiltration curve does not leak until rainfall intensity exceeding the infiltration rate of the soil occurs, and runoff occurs in rainfall exceeding infiltration capacity. This is related to the surge of flood volume during heavy rainfall. If rainfall exceeding the penetration ability of the pitcher area occurs due to actual soil conditions, it is estimated that the flooding volume is increased due to impermeable localization.

Now, we compare flood runoff for effective precipitation for each technique.

Clark synthetic unit method parameters were calculated using 1: 25,000 digital map and GIS. The arrival time was calculated by using Kripich, Rziha, Kraven Ⅰ, and Kraven Ⅱ formula. Then, the Kraven Ⅱ formula was applied to the stream flow. The storage constant was applied with the Sabol formula and the CN value was applied with AMC III.

In order to derive the unit figure for each stream, we calculate the inflow flow by creating the time chart for each watershed, calculate the flow rate according to the storage constants, and calculate the unit figure corresponding to the critical duration of 12 to 24 hours (Fig. 3).

The peak flood amount and the total runoff amount were compared by applying the effective rainfall calculated from the derived units. As shown in [Table 12], the peak flood using Horton infiltration curves decreased by 27% and the total flow decreased by 35%, compared to the effective rainfall calculation method based on CN, from the starting point of the target watershed (after the confluence of Ochan River). It was considered that the inside floors decreased by 6%, 23%, 23%, 18%, 48%, and 9% and 38% respectively, while the floods and floods decreased by 21% and 52%, respectively.

Figure 4 is a graph showing the flood discharge amount according to the effective rainfall calculation method at the Hongcheon Bridge point. According to this, the peak value of Horton in the peak flood amount was 46.9% larger than that of NRCS, and the AMC-Ⅱ condition And 0.4%, respectively. In the AMC-Ⅲ condition, 18% was estimated to be small. The total outflow was estimated to be 46.9% for AMC-Ⅰ, and 18.0% for AMC-Ⅱ and 34.9% for AMC-Ⅲ.

Table 13 shows the peak flood volume and total runoff according to the effective rainfall calculation method at Hongcheon Bridge.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications can be made without departing from the invention. Accordingly, all such modifications and variations are intended to be included within the scope of the present invention.

Claims

In a method for estimating flood amount using a field penetration test,
(A) selecting a watershed for a site penetration test;
(B) conducting a watershed characterization survey in the selected watershed;
(C) selecting a site penetration test method;
(D) performing field penetration test to obtain actual penetration test data in the target watershed;
(E) estimating the effective rainfall in the target watershed according to the SWMM model using actual penetration test data; And
(F) Estimating the flood volume using the Clark Synthetic Unit method based on the calculated effective rainfall in the target watershed.

The method according to claim 1,
The step (D)
(D1) conducting a soil characterization survey on a target watershed;
(D2) selecting a site penetration test site;
(D3) performing penetration test on the ground to calculate permeability per land use;
(D4) inducing the infiltration curves of the soils; And
(D5) deriving a penetration curve according to the land use status, and calculating the flood amount using the field penetration test.

3. The method of claim 2,
The soil characteristics survey item according to the step (D1) includes soil pot, base material and sedimentation form, land use status, land use recommendation, soil drainage status, erosion possibility status, effective soil depth, , Watershed inclination status, and topsoil soil status.

The method according to claim 1,
The step (E)
(E1) determining the watershed input data including the area average slope of the watershed, the area of the impervious area, the length of the watershed and the network, the width of the watershed or bottom, and the slope of the watershed; And
And calculating an effective rainfall using the determined watershed input data (E2).

The method according to claim 1,
The step (F)
(F1) parameter; And
And calculating a flood discharge amount by analyzing the infiltration ability by the duration of the rainfall using the infiltration curve formula according to the determined parameters (F2).