KR20090111975A - Method for calculating total maximum daily load using instreamflow requirement - Google Patents

Abstract

PURPOSE: A daily maximal allowable contamination load calculation method using a river maintenance flow rate is provided to maintain the consistency between upper and lower streams and to present the realistic target amount. CONSTITUTION: A daily maximal allowable contamination load calculation method using a river maintenance flow rate is as follows. An object area for determining the river maintenance flow rate is selected. The necessary flow rate of the chosen object area and the necessary flow rate are calculated. For the necessary flow rate, the mean minimum flow and the ecology are considered according to each area stream. For the necessary flow rate, the external appearance is considered. The determined river maintenance flow rate becomes the standard flow rate.

Description

Calculation method of maximum daily permissible load using river maintenance flow {METHOD FOR CALCULATING TOTAL MAXIMUM DAILY LOAD USING INSTREAMFLOW REQUIREMENT}

The present invention relates to a method for estimating daily maximum pollution allowable load using stream maintenance, and more specifically, by using monthly stream maintenance in consideration of both ecological and landscape requirements and hydrological drainage, the amount of runoff caused by seasonal changes throughout the year. This study relates to a method for estimating the maximum daily allowable pollution load using stream maintenance, which can consider the change of water supply.

In the water quality management of rivers in public waters up to now, the concentration regulation method which does not take into consideration the acceptable pollutant load is too strict in the upstream basin with relatively few pollutants and rather in the middle and downstream basins where the pollutant is too dense. It is an irrational system that can be tolerated, and to compensate for this, the total pollution management system is currently implemented in the four major rivers in Korea.

In other words, the existing concentration regulation method which considers only the emission allowance standard without considering the allowable pollution load of the river has a fundamental limit that cannot control the increase of the pollution load due to the quantitative expansion of the waste water. Water quality management and water treatment technologies are limited to the management of discharge facilities to meet emission allowance standards, but in the total pollution management system, this includes the investigation of environmental information in the watershed, analysis of pollutant spills, prediction and reduction techniques, as well as securing flow rates. Holistic water management measures can be derived and applied.

However, in such total pollution management system, there is uncertainty in how to set the average reservoir (Q ₂₇₅ ), which is the standard flow rate announced by the Ministry of Environment, it is difficult to set the target water quality, and due to the lack of data due to flooding and the lack of data, There is a problem that correction and verification are difficult.

Therefore, it can be said that it is important to solve the problems of current water pollution total management system and to derive reasonable results. In particular, the method of calculating the existing average water storage as the standard flow rate in the dry pollution management system is the flow rate in the dry season. This overestimation can also overestimate the permissible contamination load, and in the rainy season, the flow rate is underestimated and the permissible pollution load can be underestimated.

On the other hand, in order to consider the influence of nonpoint source on the average reservoir amount, which is the standard flow rate of pollutant system, it is difficult to consider the effect of nonpoint source load due to a certain ratio reduction of point source. Although a decision support system has been developed for calculating allowable loads or calculating total maximum daily loads (TMDLs) that can take into account nonpoint sources, the uncertainty of the method for establishing the reference flow and the seasonality of runoff are among the problems of the existing total pollution control system. There is still a need for ways to consider change.

The present invention was devised to solve the above problems, and the standard flow rate of the existing pollution total management system was calculated to target one flow rate during the year by using the average low amount of water, which sets a uniform target amount throughout the year and the seasonality of the runoff. Since it is not reasonable in this obvious country, the objective of the present invention is to use a monthly stream maintenance that takes into account both the ecological and landscape required flow and hydrological drainage, so that the change of runoff due to the change of seasons throughout the year can be considered, suggesting a realistic target amount. It is to provide a method for estimating the maximum daily allowable pollution load using river maintenance.

It is another object of the present invention to maintain consistency between upstream and downstream by performing an analysis to check whether the maximum daily allowable pollution load can be maintained at the entire exit point when the maximum daily allowable pollution load (TMDL) for each heavy basin of the target river is satisfied. It is to provide a method for estimating the maximum daily allowable pollution load using river maintenance flow.

In order to achieve the above object, the present invention comprises the steps of (a) selecting the target watershed to determine the stream maintenance; (b) estimating the required flow rate in consideration of the average flow rate, ecology required flow rate and landscape for each heavy watershed in the selected target watershed; (c) comparing the average flow rate calculated in step (b), the required flow rate considering ecology with the required flow rate considering landscape, and determining a large value as the monthly stream maintenance flow rate for each heavy water basin; and (d) the step (c). Estimation of daily maximum pollution allowable load using the river maintenance flow rate comprising the step of calculating the maximum daily allowable pollution load for each heavy water basin by determining the target material and its water quality. Provide a method.

In addition, the present invention (e) when the daily maximum pollution allowable load calculated in the step (d) for each heavy water basin, the maximum daily pollution allowable load is the maximum daily pollution at the total watershed exit point whether it is suitable for the target water system Checking whether the allowable load is satisfied; (f) If the result of the check in step (e) shows that the maximum daily allowable pollution load for each heavy basin is appropriate for the target watershed, the maximum daily allowable pollution load for each heavy basin is determined by the value, and if not, the load for each heavy basin It is characterized in that it further comprises the step of determining whether or not the reasonable maximum daily allowable load of pollution again.

As described above, the method for estimating the daily maximum pollution allowable load using the stream maintenance flow rate according to the present invention can consider the change of runoff due to the change of season throughout the year by using the monthly stream maintenance flow rate considering both the ecological and landscape required flow rate and the hydrological drainage. It is possible to present realistic target quantities and to analyze whether the daily maximum pollution allowable load can be maintained at the entire exit point when the maximum water allowable load (TMDL) for each heavy water basin of the target stream is satisfied, the consistency between upstream and downstream is also performed. It is effective to maintain.

When described in detail with reference to the accompanying drawings a preferred embodiment of the present invention configured as described above are as follows.

1 is a flow chart showing an embodiment for calculating the maximum daily pollution allowable load using the river maintenance flow according to the present invention, Figure 2 is selected as the target watershed of an embodiment for determining the river maintenance flow according to the present invention Figure 3 is a view showing the watershed division of Anyangcheon, Figure 3 is a view showing the target water quality of the Anyangcheon basin selected as the target watershed according to an embodiment of the present invention, Figure 4 is selected as the target watershed of an embodiment according to the present invention A diagram comparing the simulation results with the daily maximum pollution allowable load calculation method using the river maintenance flow for the Anyang stream basin, Figure 5 shows a schematic diagram of the QUAL2E model for the Anyang stream basin selected as the target basin according to the present invention Drawing.

As shown in FIG. 1, the method for calculating the maximum daily pollution allowable load using the stream maintenance flow rate according to the present invention first determines the stream maintenance flow rate as a reference flow rate of the target water system.

Here, the stream maintenance flow is the minimum flow rate to flow in the stream, and the river maintenance flow is selected based on the dry water (Q ₃₅₅ ), but river water conservation, river ecosystem protection, river landscape conservation, saltwater intrusion prevention, river blockage prevention, river facilities And it is calculated in consideration of the required flow rate for the protection of the intake source, maintenance of the groundwater level, the above water level is the minimum flow rate that can be shared with nature as the flow rate that flowed to the dry season in the river of the natural state in the past.

Basically, the river maintenance flow rate cannot be changed unless the river's repair, flood, and environmental conditions change significantly compared to the current state, but when the natural function is newly strengthened or the artificial function is increased or decreased by demand, Can be changed accordingly.

Article 20 of Korea's River Act specifies that river flow rates should be set and announced by setting a reference point.However, such a method can be applied to the middle and large rivers of the first tributary of ten rivers and ten rivers (mainly national rivers). As the main target, studies on small and medium rivers such as local second-class rivers are currently insufficient, and since there is no measured flow rate data, most of them use the low water flow rate calculated using the non-flow method using the adjacent main water table. It is adopted as river maintenance flow rate.

Therefore, in order to determine the effective stream maintenance of the target watershed, it is necessary to understand the river environment and river characteristics such as river sulfur, various flow inflows and flows, river conditions, natural environment and social environment, and establish river tools and representative points of the river. And the required flow rate for each item for river water quality, ecosystem (fish), river landscape, water use, saltwater intrusion prevention, blockage of sewers, protection of river management facilities, and maintenance of groundwater level. It is preferable to determine a large value as the stream maintenance amount by comparing the amount of low water.

In an embodiment of the present invention, the ecology, landscape, and water quality are considered as items of the required flow rate, and the target watershed is determined by selecting the Anyangcheon watershed as shown in FIG.

On the other hand, Anyang Stream is a national river and is the first tributary of the Han River. It is a representative urban stream that flows from the supportive hills of Uiwang-si, Gyeonggi-do and flows into the Han River via Gyeonggi-do and Seoul. The second tributary of the second tributary stream is included, and divided into 20 tributary heavy water basins and the main stream adjacent basin as shown in FIG. 2 in consideration of the river network and the DEM, and the characteristics of each basin are shown in Table 1 below.

In order to determine the stream maintenance flow in the present invention, first, the amount of water to be drained must be calculated. The average flow rate was calculated for the main stream, and the standard flow rate was calculated for the tributaries where there is no facility to supply the flow downstream, such as an upstream dam. The watershed in the metered watershed is calculated by arranging the sulfur curve of any duration from historical flow data, and then annually lists the excess probability or minimum flow rate and calculates it from arithmetic mean or frequency analysis, but there is no or partial historical flow data. Uncalibrated watersheds should have been estimated using estimated watershed data or hydrologic model results in or near the watershed.

Therefore, in the present invention, a regional regression method is used to calculate a general average long distance reflecting Korean characteristics, and the following Equation 1, which is recently calculated using data of Korea, is used.

Where Q is the average dry run (cms) and A is the basin area (km ² ).

Second, we use PHABSIM (Physical HABitat SIMulation system) to estimate the required flow rate considering ecological flow, which is a conceptual and analytical structure to deal with the river flow management problem, Instream Flow Incremental Methodology (IFIM). As part of the premise that fish tend to choose their favorite maintenance conditions based on the assumption that fish respond directly to changes in the hydraulic environment, the prevalence that fewer habitats will decrease as habitat preferences decrease. In the background.

This PHABSIM is a model that performs hydraulic simulation of arbitrary flow rate and obtains the relationship between weighted available area and flow rate through habitat simulation that combines simulation results with habitat fit curve. After obtaining the relation curve of overflow, the flow rate corresponding to the maximum weighted available area is adopted as the required flow rate to preserve the ecosystem.

On the other hand, looking at the dominant species of the river in order to select the representative fish species of Anyangcheon, which is the target river of the present invention (Kee-young (2003). Anyang Stream Rehabilitation Comprehensive Measures. Gyeonggi Development Institute), Anyangcheon mainstream hunger bridge point is crucian carp, Since pyramids, Wanggokcheon, Amcheon, and Suamcheon are represented as the dominant species of each species, they are selected as representative fish species of each stream, and Dangjeongcheon, Sanboncheon, Samsungcheon, and Sambongcheon are also selected as the representative fish species. 1995. Development and Application of Determination Method of Stream Maintenance Flow The conditions for repairing habitats of representative fishes presented by Korea Water Resources Corporation, Ministry of Construction and Transportation are shown in Table 2.

Here, the hydraulic simulation in the PHABSIM is a process of simulating the water level and the flow rate while gradually increasing the flow rate, 'Anyangcheon basin comprehensive dimension plan' (Hyundai Eng., 2005. Anyangcheon basin comprehensive plan) Report, using cross-sectional data and roughness coefficients of the HEC-RAS model constructed by the Seoul Regional Construction and Management Administration, Ministry of Construction and Transportation, and performing the water level simulation using the established HEC-RAS, and the velocity simulation using the Manning formula. This is done using VELSIM.

In addition, the habitat simulation is a process of quantitatively expressing available habitats by combining a mathematical simulation and a habitat suitability curve. In the present invention, a composite suitability is calculated using a multiplication method most commonly used and each cell is calculated. After multiplying the surface area by, it is summed up to simulate the relationship between the weighted available area and the flow rate, and the flow rate when the weighted available area has the largest value is selected as the best ecological maintenance flow rate for the representative fish species.

In the present invention, in order to determine the stream maintenance flow rate, the required flow rate must be calculated in consideration of the scenery, and the flow rate required in consideration of the scenery is visual so that the river can be maintained as a natural space that can provide a rich and emotionally stable atmosphere. In the present invention, in the case of Anyangcheon basin, 'Anyangcheon Basin Overall Dimension Plan' (Hyundai Eng. (2005). Anyangcheon Basin Overall Dimension Plan. Seoul Regional Construction Management Administration, Ministry of Construction and Transportation) Landscape flow rate is calculated by considering used river cross section data, water width, velocity and depth.

That is, the feeling of high flow rate and low flow rate is based on the ratio between the targets such as the ratio of the water surface and the occupancy rate of the target space. / B), the minimum ratio (W / B) that can feel the flow is determined by considering the 20% of the width of the water, and in the case of rivers flowing through the city, it is desirable to see the flow of the flow, so you can feel the flow to some extent The flow rate is 0.2 m / s, and it is desirable to secure an average depth of 0.1 m in which the main bed material is not exposed to the water surface so that a sudden landscape change does not occur.

As a result, the stream retention in the Anyang River basin, which is calculated by comparing the required flow considering the ecology calculated using PHABSIM, the average reflow rate of Anyang stream determined by the regional regression method, and the required flow considering the landscape, is shown in Table 3. As in most rivers, the amount of ecological maintenance is higher than the average level, so in April-October, the average level of spawning, spawning, larvae, and in November-March is average, and in some cases the landscape is maintained. You can see that it is set to.

Next, after the river maintenance flow rate is determined as the reference flow rate of the target water system, the target substance and its water quality are determined to calculate the maximum daily allowable pollution load (TMDL) as follows.

To date, the Ministry of Environment has established the following Equation 2 using the target water quality and the standard flow rate for the target area management target area.

Here, the contamination amount of L _i is the target river management point i of the management target pollutant load (kg / day), the reference flow rate Q _i is the target river management point i (m ³ / s), C _i is i target river management point Management target water quality (mg / L).

In Equation 2, the reference flow rate is a flow rate that is used as a reference for the allocation of pollutant loads by the total water management unit basin and subwatershed. As the total volume management is not easy, the standard flow rate for the first total volume management was set to the average low volume over the past 10 years, including the management flow by artificial facilities such as large dams.

However, since the above method does not consider seasonal changes in nonpoint source and pollutant load, it can be referred to as a specific management system that can be applied only during the dry rainfall period. It is a method of using the river maintenance flow suggested above instead of the low water.

That is, as described above, the river maintenance flow rate is determined as the largest flow rate by comparing the ecological required quantity, hydrological drainage, and landscape flow rate, but the ecological required flow rate is determined differently according to the season. Tolerance load (TMDL) can be established.

Wherein, L _{i, t} is a reference flow rate (m ³ / s) of the target river management point i of the management target pollutant loading at time t (kg / day), Q _{i, t} is the target river management point i at time t For example, C _i is the target quality (mg / L) of total pollutant management at the target stream management point i .

In the following embodiment of the present invention will be carried out for the target material BOD, but the present invention is not limited to the BOD as the target material, the target water quality of the BOD of Anyangcheon, the target watershed is 5 for all sections according to the Ministry of Environment notice in 1991 Although it is set as a grade, 2002, the achievement year, has passed, and there is no target water quality that comprehensively examines the purpose of use and the water space of residents, but each municipality including the main stream of Anyang stream has set a new target water quality. It is a state.

In the present invention, before the new water quality index and the target water quality are presented, 2011 is set as the intermediate target year, based on the target water quality set by each local government including the main Anyang stream, and based on the treated water discharge point of the Anyang sewage treatment plant. The target water quality of BOD is set to Class 2 (3 mg / L) in the upstream section and Class 4 (10 mg / L) in the downstream section, and the streams flowing into the main stream in this section are the same as the main stream. This is shown in FIG. 3.

The stream maintenance flow rate using the results of Table 3 and the target water quality concentration using the results of Figure 3, for the Anyang stream basin by using the equation (3) presented by the month, and further using the average reservoir amount The results of the existing method of calculating the target amount of TMDL are also presented, and the partial load (TDL) of the current watershed is conventionally calculated to calculate the reduced load (Lee Gil-sung et al. (2007). Table 4 shows the comparison between the water and pollutant circulation analysis and the Hydrological Simulation Program-Fortran (HSPF) model of the Korea Water Resources Association.

For reference, the average storage amount in the existing TMDL method for calculating only one target amount using the average storage amount is a value that cannot be derived from actual observations or reference observations, and therefore the value simulated using the HSPF model is used. do.

Here, if the simulation result of the HSPF model, which is the actual pollution load (TDL), exceeds the TMDL according to the present invention, the pollution load should be reduced by establishing a new design plan in each heavy water stream by the reduced load.

4 is a result of comparing the simulation results (TDL) of the HSPF model of 11 local second-class first tributaries of Anyangcheon and the entire Anyangcheon, and the existing TMDL using the TMDL and the average reservoir amount according to the present invention.

As can be seen in FIG. 4, it can be seen that the TMDL in winter and summer reflects the actual pollutant load (TDL), which is a simulation result of the HSPF model, compared to calculating a single TMDL based on the existing average water storage. The TMDL, which is established differently according to the flow rate, can be a more realistic plan because it increases the possibility of achieving the target.

However, in the watershed where sewage treatment plants exist, such as Mokgamcheon and Anyangcheon as a whole, the target maintenance flow rate is much smaller than the actual runoff and the concentration of sewage treatment plant does not meet the target water quality. Since the treated water is reused as the maintenance water of the river, the simulation results are relatively high. Therefore, the method of calculating the TMDL according to the present invention is not applicable in a watershed where special facilities and environments exist, rather than natural conditions.

Next, check whether the last calculated TMDL is appropriate for the water system and whether it is satisfied at the whole watershed outlet, if appropriate, determine the TMDL, and if not, reduce the load for each heavy basin and again Determine whether or not.

In other words, even if the TMDL is not satisfied due to the monthly TMDL for each heavy water basin, it may not be possible to maintain the TMDL at the exit point of the entire Anyang stream.

Therefore, in the present invention, when each heavy water basin meets the monthly target maintenance flow rate and TMDL by using the water quality analysis model QUAL2E, the total load at the watershed exit point is simulated monthly, where the water quality maintenance maintenance flow rate is considered. will be.

The QUAL2E model used in the simulation complements the one developed in 'Development of Water Circulation Consolidation Technology in Anyangcheon Basin' (Lee Gil-sung (2007). Development of Water Circulation Consolidation Technology in Anyangcheon Basin. Seoul National University, Ministry of Science and Technology). The section, which was constructed from before the merger to the Siheung stream, was extended to a total length of 30.4 km to the lower part of Anyang stream, the Han River confluence point, divided into 13 reach with similar hydraulic characteristics for each stream, and divided into 0.2 km units at each reach. Anyang Sewage Treatment Plant and its tributaries are input as point sources.

Figure 5 shows a schematic diagram of the QUAL2E model for Anyangcheon, the simulation results are shown in Table 5 below.

That is, when the actual pollution load for each heavy basin satisfies the TMDL according to the present invention of Table 4 as a result of the simulation of the above embodiment, the entire Anyangcheon TMDL is the TDL at the total watershed exit point by the simulation result of the QUAL2E model of Table 5. It can be seen that it is larger than the entire Anyangcheon TMDL, so it can be seen that the TMDL according to the present invention of Table 4 is appropriate, but if it is not satisfied to reduce the TMDL of each heavy basin according to the procedure of FIG. A plan is needed and eventually configured to meet the TMDL of the exit point.

While specific preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above-described embodiments, and a person skilled in the art to which the present invention pertains has the technical gist of the present invention. Various changes can be made without departing.

1 is a flow chart showing an embodiment for calculating the maximum daily pollution allowable load using the river maintenance flow rate according to the present invention.

Figure 2 is a view showing the watershed division of Anyang stream selected as the target basin of the embodiment for determining the stream maintenance flow rate according to the present invention.

Figure 3 is a view showing the set target water quality of the Anyangcheon watershed selected as the target watershed of one embodiment according to the present invention.

4 is a view comparing the simulation results with the daily maximum pollution allowable load calculation method using the stream maintenance flow for the Anyangcheon basin selected as the target basin according to the present invention.

5 is a view showing a schematic diagram of a QUAL2E model for the Anyangcheon basin selected as the target basin according to an embodiment of the present invention.

Claims (6)

(a) selecting a target watershed for which the stream maintenance flow is to be determined; (b) estimating the required flow rate in consideration of the average flow rate, ecology required flow rate and landscape for each heavy watershed in the selected target watershed; (c) determining a large value as the monthly stream maintenance for each heavy water basin by comparing the average shortage calculated in step (b), the required flow considering the ecology, and the required flow considering the landscape; and (d) river maintenance flow rate, characterized in that the river maintenance flow rate is determined in step (c) as a reference flow rate and the target material and the target water quality is determined by calculating the maximum daily permissible pollution load for each heavy water basin Method for Estimating Daily Maximum Pollution Permissible Load Using. The method of claim 1, (e) If each heavy watershed satisfies the maximum daily allowable pollution load calculated in step (d) above, the maximum daily allowable pollution load is satisfied at the exit point of the whole basin if the calculated maximum daily pollution allowance is appropriate for the target water system. Confirming; (f) If the result of the check in step (e) shows that the maximum daily allowable pollution load for each heavy basin is appropriate for the target watershed, the maximum daily allowable pollution load for each heavy basin is determined by the value, and if not, the load for each heavy basin Decreasing the maximum maximum pollution allowable load by reducing the maximum daily allowable pollution load calculation method using the stream maintenance, characterized in that it further comprises. The method of claim 1, The average low yield in step (b) is

(Wherein, Q is the average low water flow rate, A is the watershed area) The daily maximum pollution allowable load calculation method using the stream maintenance flow rate, characterized in that. The method of claim 1, The required flow rate considering ecology in step (b) is to perform the hydraulic simulation for any flow rate using PHABSIM, and the relationship between the weighted available area and the flow rate through the habitat simulation that combines the simulation result with the habitat fit curve. A method for calculating the maximum daily allowable pollution load using a river maintenance flow rate, wherein the flow rate corresponding to the maximum weighted available area is adopted as the best necessary flow rate for the representative fish species in the target watershed. The method of claim 1, The required flow rate in consideration of the landscape in the step (b) is calculated by considering the surface width, the flow rate and the depth of the daily maximum pollution allowable load calculation method using the stream maintenance flow rate. The method of claim 1, The maximum daily allowable contamination load in the step (d) is

(Wherein, L _{i, t} is the target river management point i of the management target pollutant loading at time t, Q _{i, t} is the target river management point i of the reference flow rate at time t, C _i is i target river management point Daily maximum pollution allowable load calculation method using the stream maintenance flow rate, characterized in that the daily maximum pollution allowable load is calculated using the total amount of pollution management target water quality).

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