MAIN STREAM RESERVOIR ECOLOGICAL MODULATION METHOD CONSIDERING INCOMING WATER FROM INTERVAL TRIBUTARIES

Abstract

A main stream reservoir ecological modulation method considering incoming water from interval tributaries is provided. The method determines the contribution ratio of the incoming water from interval tributaries to first-day's water rising in a high-flow surge process and when to start ecological modulations of spawning ground sections, determines a river course routing method after a main stream and its tributaries joining and calibrating parameters, based on past hydrological data, performing river flow calculation on the discharge volume of upstream reservoirs and the flow after interval tributaries joining, and determines a main stream reservoir ecological modulation mode considering incoming water from interval tributaries.

Claims

1. A main stream reservoir ecological modulation method considering incoming water from interval tributaries, comprising the following steps: Step 1 of determining a contribution ratio of the incoming water from interval tributaries to first-day's water rising in a high-flow surge process and when to start ecological modulations of spawning ground sections, wherein Step 1 specifically comprises the following sub steps: (1) determining target fish's ecological and hydrological parameters of spawning ground sections, according to target fish's spawning monitoring data of spawning grounds and hydrological data, determining target fish's ecological and hydrological parameters of spawning ground controlled sections, that is, determining values of a rising flow Q.sub.e, an initial increase of water levels Z.sub.e, a peak flow Q.sub.m, an average flow increase dQ, and a duration of water rising D; (2) calculating the contribution ratio of the incoming water from interval tributaries to the first-day's water rising in a high-flow surge process, according to a long series of restored hydrological runoff data, calculating a frequency of high-flow surge processes in downstream spawning grounds, analyzing an influence of the incoming water from an upstream main stream and interval tributaries on the high-flow surge processes in downstream spawning grounds, determining a contribution ratio β of the incoming water from interval tributaries to the first-day's water rising in the high-flow surge process of spawning grounds; (3) determining when to start ecological modulations, according to the hydrological runoff data of controlling stations at a main stream and its tributaries, simulating a high-flow surge generation process by an IHA method, in a case that the contribution ratio β of the incoming water from interval tributaries to the first-day's water rising in the high-flow surge process of spawning grounds is greater than a threshold θ during fish spawning, selecting the rising flow Q.sub.e, the average flow increase dQ, and the duration of water rising D of interval tributaries as control indexes for starting ecological modulations, thus a starting time st for starting ecological modulations being judged according to a process of the water rising of and the incoming water from tributaries; in a case that the contribution ratio R of the incoming water from interval tributaries to the first-day's water rising in the high-flow surge process of spawning grounds is not greater than a threshold θ during fish spawning, selecting the rising flow Q.sub.e, the average flow increase dQ, and the duration of water rising D of a main stream as control indexes for starting ecological modulations, thus the starting time st for starting ecological modulations being judged according to the water rising of a main stream; Step 2 of determining a river course routing method after a main stream and its tributaries joining and calibrating parameters, based on past hydrological data, performing river flow calculation on a discharge volume of upstream reservoirs and a flow after interval tributaries joining, taking into account an inflow of other small tributaries, performing river flow calculation by a Muskingen model considered with an inflow of side branches; Step 3 of determining a main stream reservoir ecological modulation mode considering incoming water from interval tributaries, wherein Step 3 specifically comprises the following sub steps: (1) building a high-flow surge frequency simulation model of spawning ground sections, according to a high-flow surge composition of spawning ground sections and the contribution ratio of the incoming water from interval tributaries to the first-day's water rising in the high-flow surge process, determining a main stream reservoir ecological modulation mode, so as to maximize an artificial high-flow surge frequency H, that is, max|H|, where H is the determined high-flow surge frequency of spawning ground-controlled sections calculated by the ecological modulation method considering incoming water from interval tributaries; (2) determining the ecological modulation mode of the main stream reservoir coordinated to the interval incoming water, in order to coordinate to the interval incoming water to make the high-flow surge frequency H of the controlled section as large as possible, solving an outflow process of the main stream reservoir through optimization, and an outflow outst+j+1 of the main stream reservoir during st+j+1 period being deduced as Formula (3),
sy.sub.st+j+1=d.sub.0(out.sub.st+j+1+mj.sub.st+j+1)+d.sub.1(out.sub.st+j+mj.sub.st+j)+d.sub.2sy.sub.st+jQout.sub.st+j+1=(Qsy.sub.st+j+1−d.sub.1(Qout.sub.st+j+Qmj.sub.st+j)−d.sub.2Qsy.sub.st+j)/d.sub.0−Qmj.sub.st+j+1  (3) where sy.sub.st+j refers to a composite flow of the spawning ground controlled section, mj.sub.st+j refers to the flow of interval tributaries, and st is a starting period of ecological modulations, which is determined by water rising of a main stream or interval tributaries, that is, during fish spawning period β>θ in a case that a water rising process with a continuous water rising process for not less than D days, an average flow increase of not less than dQ, and a corresponding rising flow of not less than Q.sub.e occurs at a forecasted interval tributary, a main stream reservoir starts an ecological compensation modulation considering interval incoming water on a first day of interval water-rising, during β≤θ in a case that a water rising process with a continuous water rising process for not less than D days, an average flow increase of not less than dQ, and a corresponding rising flow of not less than Q.sub.e occurs at a forecasted main stream, a main stream reservoir starts an ecological compensation modulation considering interval incoming water on a first day of main stream water-rising.

2. The main stream reservoir ecological modulation method considering incoming water from interval tributaries according to claim 1, wherein, in Step 1, the starting time st for starting ecological modulations is judged according to the process of the water rising of and the incoming water from tributaries, that is, in the case that the water rising process with a continuous water rising process for not less than D days, an average flow increase of not less than dQ, and a rising flow of not less than Q.sub.e occurs at an interval tributary, the main stream reservoir begins to start the compensation modulation to meet requirements of the high-flow pulse process required for fish spawning in downstream spawning grounds; the starting time st for starting ecological modulations is judged according to water rising in a main stream, that is, in the case that the water rising process with a continuous water rising process for not less than D days, an average flow increase of not less than dQ, and a rising flow of not less than Q.sub.e occurs at a main stream, the main stream reservoir begins to start the compensation modulation considering interval tributaries to meet the requirements of the high-flow pulse process required for fish spawning in downstream spawning grounds.

3. The main stream reservoir ecological modulation method considering incoming water from interval tributaries according to claim 1, wherein, in Step 1, the duration of water rising D is a high-flow surge duration corresponding to 75% of a frequency of the high-flow surge required for fish spawning; the rising flow Q.sub.e and the average flow increase dQ are selected according to a frequency method and a maximum-minimum method, the frequency method is to assign the rising flow Q.sub.e and the average flow increase dQ to 75% of the high-flow surge of a main stream or interval tributaries during a spawning period, the maximum-minimum method is to select the maximum average flow increase in a main stream or interval tributaries during each spawning period and the corresponding rising flow, and to choose the average flow increase of continuous water rising and the corresponding minimum rising flow as the values of the average flow increase dQ of continuous water rising and corresponding rising flow Q.sub.e.

4. The main stream reservoir ecological modulation method considering incoming water from interval tributaries according to claim 1, wherein, in Step 2, a formula of the river flow calculation is $\begin{array}{cc}{Q}_{\mathrm{down},2}=d_0{Q}_{\mathrm{up},2}+d_1{Q}_{\mathrm{up},1}+d_2{Q}_{\mathrm{down},1}& \left(1\right)\end{array}$ $d_0=\left(1+\alpha \right)\frac{\frac{1}{2}\Delta t-\mathrm{kx}}{k-\mathrm{kx}+\frac{1}{2}\Delta t},$ $d_1=\left(1+\alpha \right)\frac{\frac{1}{2}\Delta t-\mathrm{kx}}{k-\mathrm{kx}+\frac{1}{2}\Delta t},$ $d_2=\left(1+\alpha \right)\frac{k-\frac{1}{2}\Delta t-\mathrm{kx}}{k-\mathrm{kx}+\frac{1}{2}\Delta t}$ where Q.sub.down,2 is an interval end flow of a downstream spawning ground controlled section, Q.sub.up,2 is an interval end flow of a upstream main stream-tributary-joint section, Q.sub.up,1 is an interval beginning flow of an upstream main stream-tributary-joint section, Q.sub.up,1 is an interval beginning flow of a downstream spawning ground controlled section, Δt is a calculation interval, k is a storage flow-discharge relationship curve, x is a flow proportion factor, a is a contribution ratio of the incoming water of interval tributaries to the joint section, and coefficients of the river flow calculation d.sub.0, d.sub.1 and d.sub.2 are calibrated by Least Square Method according to the long series of flow measured over many years.

5. The main stream reservoir ecological modulation method considering incoming water from interval tributaries according to claim 1, wherein, in Step 3, according to the main stream reservoir compensation modulation considering incoming water from interval tributaries, the high-flow surge frequency H of the spawning ground controlled section considering incoming water from interval tributaries is calculated, when the composite flow of spawning ground sections meets conditions in following Formula, it is counted as 1 surge act,
sy.sub.st+i<sy.sub.st+i+1−d,i=0,1 . . . day
sy.sub.st+1−sy.sub.st>Ze
sy.sub.st>e
max(sy.sub.st+i . . . sy.sub.st+day)>m where the values of the rising flow Q.sub.e, the initial increase of water levels Z.sub.e, the peak flow Q.sub.m, the average flow increase dQ and the duration of water rising D come from Step 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a topological relationship diagram of the water system of a river's main stream and its tributaries.

[0019] FIG. 2 shows the surge flow process in three instances at Zhutuo Station in 2000.

[0020] FIG. 3 shows the surge flow process in three instances at Zhutuo Station in 2010.

[0021] FIG. 4 shows the surge flow process in three instances at Zhutuo Station in 1986.

DETAILED DESCRIPTION

[0022] The embodiments of the present invention will be described in detail in combination with the drawings, and the technical solutions of the present invention will be described clearly and completely. However, such descriptions do not impose limitations on the present invention, only as examples, furthermore, make the advantages of the present invention clearer and easier to be understood.

[0023] The present invention takes the ecological modulation of the fish laying pelagic eggs perching in Xiangjiaba˜Chongqing Reach in the downstream of the Jinsha River as an example, adopting the method which also has a guiding significance for the ecological modulation of other rivers, provided by the present invention for detailed descriptions.

[0024] Sichuan-Chongqing Reach along the Jinsha River from Yibin to Chongqing is a national nature reserve for the rare and peculiar fish in the upper reaches of the Yangtze River, with about 387 km in length, the hydropower stations such as Xiluodu and Xiangjiaba in its upper reaches, and the Minjiang River, the Chishui River, the Tuojiang River and other larger tributaries among this reach, in which the representative fish laying pelagic eggs include golden loaches and elongate loaches, and in the downstream of which their spawning grounds are near Zhutuo Station. As the Xiangjiaba and Xiluodu hydropower stations were successively built and put into use in 2012, the runoff patterns of the Sichuan˜Chongqing downstream reach have been changed to a great extent, and especially affect the ecological and hydrological process during the spawning period of the nature reserve from May to July, making against the natural reproduction of the fish laying pelagic eggs.

[0025] The example of the present invention provides a main stream reservoir ecological modulation method considering incoming water from interval tributaries, which includes the following steps.

[0026] Step 1: Determining the Start-Up Index of the Ecological Modulation of Spawning Ground Sections and the Ratio of the Contribution to the Incoming Water from Tributaries.

[0027] 1. Determining the Ecological and Hydrological Parameters of Spawning Ground Sections.

[0028] According to the currently available fish-spawned monitoring data and hydrological data (2009-2015) in spawning grounds, a high-flow surge process has to occur at Zhutuo Station in May and mid-June to early-July, respectively, to meet the requirements of the fish laying pelagic eggs. Specific ecological and hydrological requirements are as follow. The daily flow increase of the main stream high-flow at Zhutuo Station, that is, the average flow increase dQ is assigned to 700 in May, and 760 during mid-June to early-July. The duration of continuous incoming water with high-flow surges, that is, the duration of water rising D is assigned to 2 in May, and 3 during mid-June to early-July. The first-day's water rising, that is, the initial increase of water levels Z.sub.e is assigned to 900 in May, and 1200 during mid-June to early-July. The rising flow Q.sub.e is assigned to 3900 in May, and 6500 during mid-June to early-July. The peak flow Q.sub.m is assigned to 6200 in May, and 14000 during mid-June to early-July.

[0029] 2. Calculating the Contribution Ratio of the Incoming Water from Interval Tributaries to the First-Day's Water Rising in the High-Flow Surge Process.

[0030] The Minjiang River among tributaries has a relatively large drainage area under control, and the amount of incoming water from April to July from 1954 to 2012 accounted for 34.93% of Zhutuo Station. There were 240 simultaneous high-flow surges at Gaochang Station of the Minjiang River among 247 high-flow surges occurred at Zhutuo Station in the main stream of the Yangtze River, accounting for 97.17% of the high-flow surges at Zhutuo Station. The average ratio R of the Minjiang River's contribution to Zhutuo Station's first-day's water rising with high-flow surges from April to July is 36.7% through calculations. The measured data over the years show that at least one high-flow surge of the Minjiang River encounters the high-flow surge of Zhutuo Station every year, contributing a lot to the first-day's water rising of Zhutuo Station with high-flow surges.

[0031] 3. Determining when to Start Ecological Modulations.

[0032] The high-flow surge-generating processes for the hydrological runoff process of Jinsha River Pingshan Station (now Xiangjiaba Station) and Minjiang Gaochang Station from 1954 to 2012 were simulated by adopting the IHA method. Because the average ratio R (36.7%) of the Minjiang River's contribution to Zhutuo Station's first-day's water rising with high-flow surges from April to July is greater than the threshold (30%), the starting period of ecological modulations st was judged by water rising at the Minjiang River, that is, the water rising process with a continuous water rising process for not less than 2 days, an average flow increase of not less than 290 m.sup.3/s, and a corresponding rising flow of not less than 1413 m.sup.3/s occurred at the forecasted interval of the Minjiang River in May; the water rising process with a continuous water rising process for not less than 2 days, an average flow increase of not less than 2495 m.sup.3/s, and a corresponding rising flow of not less than 2330 m.sup.3/s occurred during mid-June to early-July. When meeting the above-mentioned ecological modulation starting conditions, the Xiluodu and Xiangjiaba reservoirs in the main stream of the Jinsha River will start an ecological compensation modulation on the first day of water rising at the Minjiang River.

[0033] Step 2: Determining a River Course Routing Method after a Main Stream and its Tributaries Joining and Calibrating Parameters.

[0034] Based on the daily runoff data derived from Xiangjiaba Station (original Pingshan Station), Gaochang Station, and Zhutuo Station during 1954˜April to July 2012, the distance difference between Xiangjiaba Station and Gaochang Station to the junction of the Jinsha River and the Minjiang River is not very large, so the flow at Zhutuo Station on the lower section is calculated by the Muskingen model, while the runoffs at Xiangjiaba Station (original Pingshan Station) and Gaochang Station are directly added together as the flow on the upper section. In addition to the Jinsha River and the Minjiang River, there are tributaries such as the Chishui River, the Tuojiang River, and the Hengjiang River in the upstream of Zhutuo Station, thus for the Muskingen model considered with the inflow of side branches, the Least Square Method is used to calculate deduction parameters d0, d1, and d2 to give d0=0.150, d1=0.495, d2=0.437, with the fitting correlation coefficient of R=0.994, so the fitting effect is better.

[0035] Step 3: Determining a Main Stream Reservoir Ecological Modulation Mode Considering Incoming Water from Interval Tributaries.

[0036] 1. Building the High-Flow Surge Frequency Simulation Model of Spawning Ground Sections.

[0037] We maximized the artificial high-flow surge frequency H at Zhutuo Station in the spawning ground, that is, max|H|. In this expression, H is the determined high-flow surge frequency of the spawning ground-controlled section calculated by the ecological modulation method considering incoming water from the tributary of the Minjiang River. When the composite flow of spawning ground sections sy.sub.st+j, meets the following conditions, it is counted as 1 surge act.

sy.sub.st+i<sy.sub.st+i+1−d,i=0,1 . . . day

sy.sub.st+1−sy.sub.st>Ze

sy.sub.st>e

max(sy.sub.st+i . . . sy.sub.st+day)>m

[0038] In the formula, the daily flow increase dQ of the main stream high-flow at Zhutuo Station is assigned to 700 in May, and 760 during mid-June to early-July; the duration day of continuous incoming water with high-flow surges is assigned to 2 in May, and 3 during mid-June to early-July; the first-day's water rising Z.sub.e is assigned to 900 in May, and 1200 during mid-June to early-July; the rising flow Q.sub.e is assigned to 3900 in May, and 6500 during mid-June to early-July; The peak flow Q.sub.m is assigned to 6200 in May, and 14000 during mid-June to early-July.

[0039] 2. Determining the Ecological Modulation Mode of the Main Stream Reservoir Coordinated to the Interval Incoming Water.

[0040] In order to coordinate to the interval incoming water to make the high-flow surge frequency H of the controlled section as large as possible, the outflow process of the main stream reservoir is solved through optimization, and the outflow outst+j+1 of the main stream reservoir during st+j+1 period is deduced as Formula (3).

sy.sub.st+j+1=0.15*(out.sub.st+j+1+mj.sub.st+j+1)+0.495*(out.sub.st+j+mj.sub.st+j)+0.437*sy.sub.st+jQout.sub.st+j+1=(Qsy.sub.st+j+1−0.495*(Qout.sub.st+j+Qmj.sub.st+j)−0.437*Qsy.sub.st+j)/0.15−Qmj.sub.st++1j  (3)

[0041] In the formula, sy.sub.st+j refers to the composite flow of the spawning ground controlled section, mj.sub.st+j refers to the flow of the Minjiang River in the interval tributary, and st is the starting period of ecological modulations, which is determined by the water rising at the Minjiang River, that is, when the water rising process with a continuous water rising process for not less than 2 days, an average flow increase of not less than 290 m.sup.3/s, and a corresponding rising flow of not less than 1413 m.sup.3/s occurs at the forecasted interval of the Minjiang River in May; when the water rising process with a continuous water rising process for not less than 2 days, an average flow increase of not less than 2495 m.sup.3/s, and a corresponding rising flow of not less than 2330 m.sup.3/s occurs during mid-June to early-July, the Xiluodu and Xiangjiaba reservoirs in the main stream of the Jinsha River will start an ecological compensation modulation on the first day of water rising at the Minjiang River.

[0042] The years 2000, 2010 and 1986 are selected as the typical high-flow year, normal flow year and low water year for Zhutuo Station. According to the above model, the outflow process of the main stream reservoir is calculated through optimization to get the ecological modulation mode.

[0043] For the three situations such as a natural situation, a regular modulation and ecological modulation mode considering incoming water from interval tributaries, the high-flow surge frequencies H0, H1 and H of the spawning ground controlled section at Zhutuo station are calculated in sequence. Specifically, according to the long series of hydrological data, the composite rule of incoming water to the spawning ground controlled section under natural conditions is analyzed, and the high-flow surge frequency H.sub.0 of the spawning ground controlled section under natural conditions is calculated. According to the regular modulation rule of the main stream reservoir, the high-flow surge frequency H.sub.1 of the spawning ground controlled section under the regular modulation is calculated. According to the main stream reservoir compensation modulation considering incoming water from interval tributaries, the high-flow surge frequency H of the spawning ground controlled section considering incoming water from interval tributaries is calculated. The calculation results are shown in Tables 1˜3, and the surge process is shown in FIGS. 2˜4.

[0044] 2000: Under natural conditions, 2 high-flow surges occurred at Zhutuo Station, but no high-flow surge occurred in the conventional modulation plan, while the ecological modulation plan guaranteed 2 occurrences of high-flow surges, and each indicator of high-flow surges met the requirements of the continuous water rising process for fish spawning, retaining the frequency of high-flow surges at Zhutuo Station, that is, H.sub.0=2, H.sub.1=0, H=2.

[0045] 2010: Under natural conditions, 3 high-flow surges occurred at Zhutuo Station, but no high-flow surge occurred in the conventional modulation plan from May to early July, while the ecological modulation plan guaranteed 2 occurrences of high-flow surges, and each indicator of high-flow surges met the requirements of the continuous water rising process for fish spawning, with the average daily increase of high-flows at Zhutuo Station wholly higher than the average daily increase of high-flows under natural conditions, that is, H.sub.0=3, H.sub.1=0, H=2.

[0046] 1986: Under natural conditions, 4 high-flow surges occurred at Zhutuo Station, 1 high-flow surge occurred in the conventional modulation plan, the ecological modulation plan initiated 2 ecological modulations, resulting in 4 high-flow surge processes at Zhutuo Station, and each indicator of high-flow surges met the requirements of the continuous water rising process for fish spawning, that is, H.sub.0=4, H.sub.1=1, H=4.

[0047] In summary, compared with conventional modulations, the main stream reservoir ecological modulation plan provided by the present invention effectively increases the frequency of the high-flow surge process, which is beneficial to the natural reproduction of the fish laying pelagic eggs in spawning grounds.

TABLE-US-00001 TABLE 1 Statistical Table of High-flow Surge Characteristics Indexes at Zhutuo Station in 2000 (high-flow year) average first-day's flow duration occurrence duration/ water rising increase/ peak of water modulation plan time day rising flow/m.sup.3/s m.sup.3/s flow/m.sup.3/s rising/d natural conditions 5.22-6.7 16 24.41% 4630 731 15600 15  6.12-7.15 38 17.45% 4900 612 25100 33 conventional / / / / / / / modulation ecological  5.8-5.13 5 18.43% 4882 700 6982 3 modulation 6.11-7.3 23 15.00% 13451 946.5 17237 4

TABLE-US-00002 TABLE 2 Statistical Table of High-flow Surge Situation at Zhutuo Station in 2000 (normal flow year) average first-day's flow duration occurrence duration/ water rising increase/ peak of water modulation plan time day rising flow/m.sup.3/s m.sup.3/s flow/m.sup.3/s rising/d natural conditions 5.10-5.23 13 16.99% 4650 187 6520 10 5.31-6.20 20 19.44% 6070 333 12400 19 6.22-7.12 20 16.19% 10500 517 19800 18 conventional / / / / / / / modulation ecological 5.19-5.24 5 15.32% 5875 700 7974 3 modulation  7.9-7.28 19 15.00% 11009 1070 25882 10

TABLE-US-00003 TABLE 3 Statistical Table of High-flow Surge Situation at Zhutuo Station in 1986 (low water year) average first-day's flow duration occurrence duration/ water rising increase/ peak of water modulation plan time day rising flow/m.sup.3/s m.sup.3/s flow/m.sup.3/s rising/d natural conditions 5.19-6.11 23 38.95% 4210 181 8190 22 6.15-6.18 3 19.68% 5540 1650 8840 2 6.19-6.23 4 29.66% 7080 2710 12500 2 6.30-7.5  5 18.06% 7750 4550 21400 3 conventional  6.4-7.13 39 15.32% 5668 270 15645 37 modulation ecological 5.20-5.25 5 20.81% 4325 700 6425 3 modulation  6.3-6.13 9 16.8%% 4274 676 9008 7 6.15-6.20 5 15.28% 7852 1037 12000 4  7.4-7.13 9 18.07% 10210 776 15645 7

[0048] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. All the changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention should cover the protection scope of the present invention. Therefore, the protection scope of the present invention should depend on the protection scope of the claims.