Design method of drought-resistant water source reserve for reservoir groups with different low flow levels and compositions

Abstract

The drought-resistant water source reserve design method for reservoir groups with different dry flow levels and compositions includes the following steps: Step 1, establish a set of water supply guarantee and water resources control indicators CIS in the basin; Step 2, establish a series of reservoirs WRSL for the overall water situation in the basin; Step 3, identify typical drought water shortage years in the basin; Step 4, deduce the overall dry flow design composition process with different frequencies of typical water shortage years; Step 5, analyze and calculate the water shortage in the basin and its temporal and spatial distribution; Step 6, determine the drought-resistant water source reserve and allocation of the reservoir group in the basin. Under the premise of ensuring flood control safety, this method effectively responds to the increasingly frequent water supply shortage problem of extreme dry events under the new situation, and provides technical support for flood and drought disaster prevention in the new stage.

Description

Technical Field

[0001] The invention relates to the technical field of river basin drought resistance and water safety guarantee, and in particular to a drought resistance water source reserve design method for reservoir groups with different dry flow levels and compositions. Background Art

[0002] Improving the flood and drought disaster prevention capabilities of the basin is an important part of the water security of the basin. In the past, when the comprehensive planning of rivers and the design of water conservancy and hydropower projects were carried out, the focus was usually on the protection needs of important flood protection objects, and characteristic parameters such as reservoir flood limit water level and flood control storage capacity were set to ensure the flood control safety of the basin under the corresponding protection standards. However, no corresponding characteristic parameters were set for the drought in the basin. With the rapid development of the economy and society and the impact of global warming, the demand for water resources has increased significantly. In addition, under the dual influence of extreme climate events and strong human activities in recent years, the problem of drought and water shortage has become increasingly serious. The number of extreme drought events in the Yangtze River Basin and the southwestern rivers has increased a lot compared with the past. The disaster risk pattern remains unchanged, but the high-value area has increased significantly. From June to August 2022, the entire Yangtze River Basin encountered varying degrees of continuous high temperature and drought in summer, and the extreme phenomenon of "anti-dryness during the flood season" rarely occurred, which had a serious impact on the economic life of the people in the relevant provinces and regions of the basin. Therefore, it is urgent to carry out emergency reserve water source planning research in the Yangtze River Basin under extreme drought conditions in the face of the current changes in the water resources carrying pattern of the Yangtze River Basin.

[0003] On the other hand, with the rapid development of water conservancy and hydropower engineering construction in my country, it has changed from "engineering water conservancy" with construction as the main focus to "resource water conservancy" with how to dispatch and utilize these water conservancy projects. At present, the water conservancy project system in the Yangtze River Basin has been basically completed and put into operation. Water conservancy projects are an important means to regulate the uneven temporal and spatial distribution of water resources in the basin and to respond to droughts and ensure water supply security. The large-scale control reservoirs of main and tributary rivers have provided the possibility for planning drought-resistant water sources and reserve water sources. How to use scientific methods for design and planning is worth selecting specific basins for practical research.

[0004] Problems with existing technologies: When analyzing and studying low-water conditions, existing technologies still focus on single control nodes or protected objects, but rarely rise to the large-scale spatial and temporal scale of the basin to explore the large-scale multi-regional low-water condition analysis and calculation methods that meet different scenarios such as different low-water levels and regional compositions in the basin. There are limitations that only apply to single specific objects and smaller regional scopes. At the same time, when considering drought-resistant scheduling of reservoirs, existing technologies mostly operate strictly in accordance with the original design characteristic water level, or implement emergency dynamic control, and can only respond to limited droughts in an emergency. There is no systematic response to drought-resistant water source storage capacity for basin reservoirs with different low-water levels and compositions, and there is a gap from the requirements of "water security guarantee capabilities" in the new era.

[0005] Therefore, it is necessary to design a drought-resistant water reserve design method for reservoir groups with different low flow levels and compositions to overcome the above problems. Summary of the invention

[0006] In order to avoid the above problems, a drought-resistant water reserve design method for reservoir groups with different dry flow levels and compositions is provided to provide technical support for drought-resistant scheduling and water security in the basin.

[0007] The drought-resistant water source reserve design method for reservoir groups with different low water levels and compositions provided by the present invention comprises the following steps:

[0008] Step 1: Establish a CIS for water supply security and water resources management indicators in the basin;

[0009] Step 2, establish the basin overall water regime series library WRSL;

[0010] Step 3, identify the typical water shortage year type of the basin drought;

[0011] Step 4, deriving the overall low water design composition process of different frequencies in typical water shortage years;

[0012] Step 5: Analyze and calculate the water shortage in the basin and its temporal and spatial distribution;

[0013] Step 6: Determine the drought-resistant water reserve and allocation of the basin reservoir group.

[0014] Preferably, step 1 includes the following sub-steps:

[0015] 1.1 According to the research object and objectives, the distribution of water users in the study area is taken into consideration, the natural water system topology, water project layout and water resources management requirements are considered, the control section CC for analyzing and calculating the drought-resistant water source storage capacity is determined, and the control section set CCS is established:

[0016] CCS{CC1,...,CC i ,...,CC N};

[0017] Among them, CC i is the control section of the i-th drought-resistant water source storage capacity, i ranges from 1 to N, and N is the total number of control sections;

[0018] 1.2 For control sections with water supply guarantee tasks, the water supply guarantee demand of the specified water supply objects is used as the water supply guarantee threshold WST. For control sections with water resources management objectives, the outer envelope value of the approved ecological flow guarantee target value and the minimum downstream flow value is used as the water resources control threshold WRMT. The water supply guarantee and water resources control threshold set CTS of the above control sections is established:

[0019]

[0020] Among them, Qs t Qc is the safe water intake flow rate for water supply in period t, t is the safe discharge flow of water resources control in the tth period, T is the total number of periods, if the period step is day, then T is the total number of days in the historical sequence; if the period step is ten days, then T is the total number of ten days in the historical sequence; if the period step is month, then T is the total number of months in the historical sequence;

[0021] 1.3 When the water supply guarantee threshold WST and water resources management threshold WRMT of the control section are water level or water volume values, they are converted into flow values ​​through the water level-flow relationship and the corresponding duration of water volume; on this basis, considering the changes in the annual time distribution of WST and WRMT, according to the distribution of the control sections in the basin and the requirements of the threshold indicators, the appropriate duration is selected as the time step, and the annual time distribution process of WST and WRMT is established to form the control indicator set CIS:

[0022]

[0023] Preferably, the control sections include river basins, regional key water supply guarantee sections, main and tributary water resources management sections, and water conservancy and hydropower project sections; if there are hydrological stations near the upstream and downstream of the control sections, the hydrological process is directly analyzed and calculated using the hydrological observation data; if there are no hydrological observation sections upstream and downstream, the hydrological process of the section is inferred by the hydrological analogy method.

[0024] Preferably, step 2 comprises the following steps:

[0025] 2.1 The long-series flow and water level observation data of the control section CC are used to form the water regime historical data set HHDS, and the long-series mean values ​​of flow and water level of different durations, coefficient of variation CV, coefficient of skewness CS and different frequency design values ​​are used to form the water regime result data set HRDS;

[0026] 2.2 The historical water regime dataset HHDS and the water regime result dataset HRDS of the integrated control section CC are used to build the basin-wide water regime series database WRSL:

[0027]

[0028] Among them, FL is the runoff observation data, Qo t is the flow observation value at time t, Qr t is the interval flow value of duration t, WL is the water level observation data, Zo t is the water level observation value during the period t; is the flow value of the sth upstream section for a duration of t, and S is the number of sections upstream of the control section;

[0029] RFL is the runoff design result set, Qa is the mean of the flow series, QCV is the coefficient of variation of the flow series, QCS is the skewness coefficient of the flow series, Qs p is the design value of the flow series frequency p; RWL is the water level design result set, Za is the mean of the water level series, ZCV is the coefficient of variation of the water level series, ZCS is the skewness coefficient of the water level series, Zs p is the design value of the water level series frequency p.

[0030] Preferably, the frequency P is selected according to the design requirements and in accordance with the provisions of the "Specifications for Hydrological Calculations of Water Conservancy and Hydropower Projects". If there is no existing design value result for the control section CC, the analysis and calculation shall be carried out in accordance with the methods specified in the "Specifications for Hydrological Calculations of Water Conservancy and Hydropower Projects".

[0031] Preferably, step 3 includes the following sub-steps:

[0032] 3.1 According to the topological structure of the water system in the basin, the long series of water shortage situations of the control sections are analyzed step by step from the upstream, and the incoming flow sequence IF, the downstream flow sequence DF, the interval water shortage flow sequence ISF and the cumulative water shortage flow sequence CSF of each control section are analyzed and calculated, and then the water shortage information set WSIS is constructed:

[0033]

[0034] Among them, Qi t is the incoming flow during time t, Qd t is the discharge flow during time t, Qis t is the interval water shortage flow during the duration t, Qcs t is the cumulative water shortage flow during time t; is the discharge flow of the sth upstream section for a period of time t, is the cumulative water shortage flow of the sth upstream section for a period of time t, and S is the number of sections upstream of the control section;

[0035] 3.2According to the cumulative water shortage flow Qcs of the control section t Sequence, calculate the cumulative water shortage Ws year by year y , and sort in descending order {Max(Ws y ), …, Min(Ws y On this basis, combined with the characteristics of the basin division, the maximum cumulative water shortage year of the control section of the main and tributary nodes or important guarantee nodes is taken as the typical water shortage year type CC of the division. i -TST(y);

[0036] in, Ty is the total number of time periods in year y.

[0037] Preferably, step 4 includes the following sub-steps:

[0038] 4.1 The annual average flow Qo of each control section in different typical years y y Compared with the corresponding design flow, the flow ratio coefficient MCQ of the typical year y is derived y-p , establish the low water magnification ratio matrix MCS = {MCQ 1-p , MCQ y-p , MCQ Y-p}, Y is the total number of typical years;

[0039] 4.2 Design low-flow flow TOS-Qs based on the total outlet section TOS of the basin p To control, according to the typical year y same multiple coefficient TOS-MCQ y-p Amplify and deduce the flow process of other control sections to form the overall low-flow design process set DDPS with a typical year y frequency p yp :

[0040]

[0041] Among them, DDP i is the design flow process sequence of section i in a typical year y with frequency p, is the flow observation value of the tth period at the i-th section, The flow rate of the i-th section in the t-th period of the typical year y frequency p; The interval flow of the ith section in the tth period, is the flow rate of the sth upstream section of the ith section in the tth period.

[0042] Preferably, step 5 specifically includes: for the overall low water design composition process of each frequency in different typical years, repeat step 3.1 to analyze and calculate the spatiotemporal distribution of water shortage of each frequency in different typical years in the basin, analyze the long series of water shortage situation of the control section step by step from the upstream, analyze and calculate the incoming flow sequence TST-IF, the downstream flow sequence TST-DF, the interval water shortage flow sequence TST-ISF and the cumulative water shortage flow sequence TST-CSF of each control section, and then construct the water shortage information matrix YPWSM of each frequency in different typical years:

[0043]

[0044]

[0045] Among them, y_p_Qi t is the inflow volume at frequency p in period t in a typical year, y_p_Qd t is the discharge flow at frequency p in period t in a typical year, y_p_Qis t is the interval water shortage flow at the tth period of the y-frequency p period in a typical year, y_p_Qcst is the cumulative water shortage flow in the tth period of frequency p in a typical year y; is the discharge flow of the sth upstream section at the tth period of the typical year y frequency p, is the cumulative water shortage flow of the sth upstream section in the tth period of typical year y frequency p, and S is the number of sections upstream of the control section.

[0046] Preferably, step 6 includes the following sub-steps:

[0047] 6.1 Divide K sub-regions SP with reservoirs as nodes, clarify the control sections SPCS within the sub-region and the cascade reservoir groups SPCR above the sub-region; according to the design results of the cascade reservoir group, extract the normal water level NWL, dead water level DWL, flood limit water level FLL, available storage capacity RS, sub-region storage capacity coefficient set PCC and water level storage capacity curve SCC of each reservoir, and establish the water level storage capacity information set CR-LCIS of the cascade reservoir group in the basin:

[0048]

[0049] Among them, NWL j is the normal water level of the jth reservoir, DWL j is the dead water level of the jth reservoir, FLL j is the flood limit water level of the jth reservoir, RS j is the available storage capacity of the jth reservoir, PCC j is the partition capacity coefficient set of the jth reservoir, SCC j is the water level and storage capacity curve of the jth reservoir;

[0050] PcC k is the storage capacity coefficient of the jth reservoir in partition k, RS b is the available storage capacity of the bth reservoir upstream of partition k, B is the number of reservoirs upstream of partition k; j is the water level of the jth reservoir, w j is the water level z of the jth reservoir j The corresponding storage capacity; f(z j ,w j ) is the water level z j With Ku Rong j Curve function, positive function f() uses reservoir capacity to calculate water level, f -1 () The reservoir capacity is calculated based on the water level, where R is the number of reservoirs in the cascade reservoir group;

[0051] 6.2 Using the interval water shortage flow sequence TST-ISF of the control section SPCS in the sub-district, the sub-district cumulative water shortage time sequence PCWS of each frequency in different typical years of each sub-district is summed up to form the water shortage time sequence set SP_WSS of each frequency in different typical years of the sub-district:

[0052]

[0053] Among them, y_p_Qscs k_t is the interval cumulative water shortage flow in the tth period of the typical year y frequency p of the kth interval, and K is the total number of intervals; is the interval water shortage flow of the mth section in the kth interval in the typical year y frequency p tth period, M is the number of control sections in the kth interval;

[0054] 6.3 For different typical water shortage processes of different frequencies, starting from the most downstream sub-district, the accumulated water shortage of the sub-district is used as the sub-district drought-resistant water source reserve storage capacity (PDC) that needs to be reserved for the cascade reservoir group SPCR above the sub-district. k , using the storage capacity coefficient PCc of the upstream reservoir in the sub-region k As the allocation coefficient, the sub-district cumulative water shortage schedule is allocated to each reservoir as the sub-drought-resistant water source storage capacity sequence SDCS that the reservoir needs to bear in the sub-district; on this basis, the sub-drought-resistant water source storage capacity sequences that each reservoir needs to bear are accumulated and summed to obtain the drought-resistant water source storage capacity reservation schedule DSSC of each reservoir; taking the flood limit water level as the water level value of the end period of the scheduling period, it is accumulated in reverse order from the end period of the scheduling period to the beginning period of the scheduling period to obtain the corresponding water level sequence SP-DSSL of the drought-resistant water source storage capacity of each reservoir; on this basis, the drought-resistant water source storage capacity DRCL of the basin cascade reservoir group corresponding to different typical frequencies is formed;

[0055]

[0056] Preferably, in step 6.1, the reservoir capacity between the positive water level and the lowest operable water level is used, and the lowest operable water level selects the flood limit water level or the dead water level. For special characteristic water level parameters such as the extreme dead water level and the extreme drawdown water level, they are selected according to actual conditions and incorporated into CR-LCIS.

[0057] Compared with the prior art, the present invention has the following beneficial effects: the present invention is a design method for drought-resistant water source storage for reservoir groups with different dry water levels and compositions. For the dry years in the basin under the pattern of large-scale controlled reservoir groups, especially under the conditions of reverse dryness in the flood season, the dry water situation in the flood season is considered, and the typical dry water shortage year type and the overall dry water level and composition process of the basin can be scientifically and reasonably formulated, the water shortage in the basin and its temporal and spatial distribution can be analyzed and quantified, and the drought-resistant water source storage and distribution of the reservoir group in the basin can be determined by deduction. On the one hand, it can effectively improve the water supply security guarantee capability of the basin, and on the other hand, it can make full use of the vacant storage capacity of the reservoir under the premise of ensuring flood control safety, effectively respond to the increasingly frequent water supply shortage problem of extreme dry water events under the new situation, and provide technical support for flood and drought disaster prevention in the new stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1It is a flow chart of the drought-resistant water source storage design method for river basin reservoir groups with different low water levels and compositions according to the present invention;

[0059] Figure 2 A topological structure of natural water systems, layout of water projects, and distribution map of control sections in a preferred embodiment of the present invention;

[0060] Figure 3 It is a time distribution diagram of the reserve water level of the drought-resistant water source of the No. 1 reservoir in the study area of ​​a preferred embodiment of the present invention;

[0061] Figure 4 It is a time distribution diagram of the reserve water level of the 2# reservoir drought-resistant water source in the study area of ​​a preferred embodiment of the present invention;

[0062] Figure 5 It is a time distribution diagram of the reserve water level of the 3# reservoir drought-resistant water source in the study area of ​​a preferred embodiment of the present invention;

[0063] Figure 6 It is a time distribution diagram of the reserve water level of the 4# reservoir drought-resistant water source in the study area of ​​a preferred embodiment of the present invention;

[0064] Figure 7 This is a time distribution diagram of the reserve water level of the 6# reservoir drought-resistant water source in the study area of ​​a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0065] The drought-resistant water source reserve design method for reservoir groups with different low water levels and compositions provided in this embodiment includes the following steps:

[0066] Step 1: Establish a set of indicators for water supply security and water resources management in the basin, including:

[0067] 1.1 The distribution of water users in the study area selected in this embodiment, the topological structure of the natural water system, the layout of water projects, and the distribution of water resource control sections are as follows: Figure 2 As shown in the figure, CC1 is the key water supply guarantee section in the basin and region, and CC2 is the water resources control section, which constitutes the control section set CCS.

[0068] 1.2 Establish a set of water supply guarantee and water resources management thresholds for control sections.

[0069] This embodiment only uses the ten-day time scale as an example. For the water supply guarantee control section CC1, the water supply guarantee threshold WST (the water supply volume in ten days is about 120 million m 3 ), for the water resources control section CC2, the approved ecological flow guarantee target is used as the water resources control threshold WRMT (the ecological flow guarantee water volume per ten-day period is about 5 billion m 3), establish the water supply guarantee and water resources control threshold set CTS for the above control sections, and comprehensively form the control indicator set CIS.

[0070] Step 2: Establish a basin-wide water regime database WRSL, including:

[0071] 2.1 The long series flow observation data of control sections CC1 and CC2 from 1951 to 2022 form the water regime historical data set HHDS; the long series flow and water level mean, coefficient of variation CV, skewness coefficient CS and different frequency design values ​​form the water regime result data set HRDS.

[0072] 2.2 The historical water regime dataset HHDS and the water regime result dataset HRDS of the integrated control sections CC1 and CC2 are used to construct the basin-wide water regime series library WRSL.

[0073] Step 3: Identify typical drought and water shortage patterns in the basin, including:

[0074] 3.1 Analyze and calculate the spatiotemporal distribution of historical water shortage in the basin. According to the topological structure of the water system in the basin, the long series of water shortages in the CC2 and CC1 control sections from 1951 to 2022 are analyzed step by step from the upstream, and the incoming flow sequence IF, the downstream flow sequence DF, the interval water shortage flow sequence ISF and the cumulative water shortage flow sequence CSF of each control section are analyzed and calculated, and then the water shortage information set WSIS is constructed.

[0075] 3.2 Identify the typical water shortage year type of the basin. According to the cumulative water shortage flow Qcs of the control section CC1 t Sequence, calculate the cumulative water shortage Ws year by year y , and sort in descending order {Max(Ws y ), …, Min(Ws y On this basis, combined with the characteristics of the basin division, the maximum cumulative water shortage year of the control section of the main and tributary nodes or important guarantee nodes is taken as the typical water shortage year type CC of the division. i -TST(y), in this embodiment, a particularly dry year is selected as a typical drought water shortage year type.

[0076] Step 4, deriving the overall low water design composition process of different frequencies in typical water shortage years;

[0077] The average annual flow Qo of each control section in the typical year of 1978 1978 , compared with the design flow corresponding to the 95% design frequency, the flow ratio coefficient MCQ for the typical year of 1978 is derived 1978-95％ , establish the low water magnification ratio matrix MCS for each typical year:

[0078] The design flow TOS-Qs of the total outlet section TOS (CC1 section in this case) of the basin is 95％ To control, the same multiple ratio coefficient TOS-MCQ of the overall low-flow runoff in the typical year of 1978 in the study area was screened out. 1978-95％ Then, the annual ten-day flow process is selected, and the coefficient TOS-MCQ of the typical year 1978 is used. 1978-95％ The flow process of CC2 section is enlarged and deduced to form the overall low-flow design process set DDPS with a frequency of 95% in the typical year of 1978. 1978(95％) .

[0079] Step 5: Analyze and calculate the water shortage in the basin and its temporal and spatial distribution;

[0080] For the overall low-flow design composition process of each frequency in the 1978 model year, repeat step 3.1 to analyze and calculate the spatiotemporal distribution of water shortages of each frequency in different typical years in the basin, analyze the long series of water shortages in the control sections step by step from the upstream, analyze and calculate the incoming flow sequence TST-IF, downstream flow sequence TST-DF, interval water shortage flow sequence TST-ISF and cumulative water shortage flow sequence TST-CSF of each control section, and then construct the water shortage information matrix YPWSM of each frequency in the typical year of 1978.

[0081] Step 6, determine the drought-resistant water reserve and allocation of the reservoir group in the basin;

[0082] 6.1 Establish the water level and storage capacity information set CR-LCIS of the cascade reservoirs in the basin.

[0083] This embodiment divides the reservoir into five sub-regions SP with the reservoir as the node, and clarifies the control section SPCS within the region and the cascade reservoir group SPCR above the region.

[0084] According to the design results of cascade reservoirs, the NWL, dead water level DWL, flood limit water level FLL, available storage capacity RS, partition storage capacity coefficient set PCC and water level storage capacity curve SCC of each reservoir are extracted to establish the water level storage capacity information set CR-LCIS of the cascade reservoirs in the basin.

[0085] 6.2 Calculate the time series of water shortage at different frequencies in different typical years within the calculation interval.

[0086] Using the interval water shortage flow sequence TST-ISF of the control section SPCS within the partition, the partition cumulative water shortage time sequence PCWS of 95% frequency in each sub-district in typical year 1978 is summed up to form the interval water shortage time sequence set SP_WSS for each frequency in typical year 1978.

[0087] 6.3 Determine the spatial and temporal distribution of drought-resistant water storage capacity of cascade reservoirs in the basin.

[0088] For each frequency of water shortage process in the typical year of 1978, starting from the most downstream sub-district, the accumulated water shortage of the sub-district is used as the sub-district drought-resistant water source storage capacity (PDC) required by the cascade reservoir group above the sub-district SPCR. k The cumulative water shortage time of the sub-district is calculated by the storage capacity coefficient PCc of the upstream reservoir of the sub-district. k is the allocation coefficient, which is allocated to each reservoir as the sub-drought-resistant water source reserve capacity sequence SDCS that the reservoir needs to bear in this partition. On this basis, all sub-drought-resistant water source reserve capacity sequences that each reservoir needs to bear are accumulated and summed to obtain the drought-resistant water source reserve capacity reservation schedule DSSC of each reservoir; taking the flood limit water level as the water level value at the end of the scheduling period, it is accumulated in reverse order from the end of the scheduling period to the beginning of the scheduling period to obtain the corresponding water level sequence SP-DSSL of the drought-resistant water source reserve capacity of each reservoir. On this basis, a drought-resistant water source reserve capacity library DRCL for the cascade reservoir group in the basin that responds to different typical frequencies is formed. The time distribution of the drought-resistant water source reserve water level of each reservoir in this embodiment is as follows: Figure 3 to Figure 7 shown.

[0089] As can be seen from the figure, in response to the basin-wide drought in 1978, the method of the present invention can analyze and quantify the water shortage in the basin and its temporal and spatial distribution, divide the water supply security deficit in the basin into the cumulative water shortage time distribution of each sub-area, and reasonably allocate it to each cascade reservoir. The drought-resistant water source reserve and reserved time distribution of the five reservoirs are determined, which effectively improves the water supply guarantee rate in the basin's dry season from November to April of the following year. It also makes full use of the vacant storage capacity of the cascade reservoirs, providing technical support for flood and drought disaster prevention in the new stage.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing drought-resistant water source reserves for reservoirs of different low water levels and compositions, characterized in that it comprises the following steps: Step 1: Establish a CIS for water supply security and water resources management indicators in the basin; Step 2, establish the basin overall water regime series library WRSL; Step 3, identify the typical water shortage year type of the basin drought; Step 4, deriving the overall low water design composition process of different frequencies in typical water shortage years; Step 5: Analyze and calculate the water shortage in the basin and its temporal and spatial distribution; Step 6, determine the drought-resistant water reserve and allocation of the reservoir group in the basin; Step 1 includes the following sub-steps: 1.1 According to the research object and objectives, the distribution of water users in the study area is taken into consideration, the natural water system topology, water project layout and water resources management requirements are considered, the control section CC for analyzing and calculating the drought-resistant water source storage capacity is determined, and the control section set CCS is established: CCS{CC1,...,CC i ,...,CC N }; in, CC i is the control section of the i-th drought-resistant water source storage capacity, i ranges from 1 to N, and N is the total number of control sections; 1.2 For control sections with water supply guarantee tasks, the water supply guarantee demand of the specified water supply objects is used as the water supply guarantee threshold WST. For control sections with water resources management objectives, the outer envelope value of the approved ecological flow guarantee target value and the minimum downstream flow value is used as the water resources control threshold WRMT. The water supply guarantee and water resources control threshold set CTS of the above control sections is established: Among them, Qs t Qc is the safe water intake flow rate for water supply in period t, t is the safe discharge flow of water resources control in the tth period, T is the total number of periods, if the period step is day, then T is the total number of days in the historical sequence; if the period step is ten days, then T is the total number of ten days in the historical sequence; if the period step is month, then T is the total number of months in the historical sequence; 1.3 When the water supply guarantee threshold WST and water resources management threshold WRMT of the control section are water level or water volume values, they are converted into flow values ​​through the water level-flow relationship and the corresponding duration of water volume; on this basis, considering the changes in the annual time distribution of WST and WRMT, according to the distribution of the control sections in the basin and the requirements of the threshold indicators, the appropriate duration is selected as the time step, and the annual time distribution process of WST and WRMT is established to form the control indicator set CIS: Step 2 includes the following steps: 2.1 The long-series flow and water level observation data of the control section CC are used to form the water regime historical data set HHDS, and the long-series mean values ​​of flow and water level of different durations, coefficient of variation CV, coefficient of skewness CS and different frequency design values ​​are used to form the water regime result data set HRDS; 2.2 The historical water regime dataset HHDS and the water regime result dataset HRDS of the integrated control section CC are used to build the basin-wide water regime series database WRSL: Among them, FL is the runoff observation data, Qo t is the flow observation value at time t, Qr t is the interval flow value of duration t, WL is the water level observation data, Zo t is the water level observation value during the period t; is the flow value of the sth upstream section for a duration of t, and S is the number of sections upstream of the control section; RFL is the runoff design result set, Qa is the mean of the flow series, QCV is the coefficient of variation of the flow series, QCS is the skewness coefficient of the flow series, Qs p is the design value of the flow series frequency p; RWL is the water level design result set, Za is the mean of the water level series, ZCV is the coefficient of variation of the water level series, ZCS is the skewness coefficient of the water level series, Zs p is the design value of the water level series frequency p; Step 3 includes the following sub-steps: 3.1 According to the topological structure of the water system in the basin, the long series of water shortage situations of the control sections are analyzed step by step from the upstream, and the incoming flow sequence IF, the downstream flow sequence DF, the interval water shortage flow sequence ISF and the cumulative water shortage flow sequence CSF of each control section are analyzed and calculated, and then the water shortage information set WSIS is constructed: Among them, Qi t is the incoming flow during time t, Qd t is the discharge flow during time t, Qis t is the interval water shortage flow during the duration t, Qcs t is the cumulative water shortage flow during time t; is the discharge flow of the sth upstream section for a period of time t, is the cumulative water shortage flow of the sth upstream section for a period of time t, and S is the number of sections upstream of the control section; 3.2According to the cumulative water shortage flow Qcs of the control section t Sequence, calculate the cumulative water shortage Ws year by year y , and sort in descending order {Max(Ws y ), …, Min(Ws y On this basis, combined with the characteristics of the basin division, the maximum cumulative water shortage year of the control section of the main and tributary nodes or important guarantee nodes is taken as the typical water shortage year type CC of the division. i -TST(y); in, Ty is the total number of time periods in year y; Step 4 includes the following sub-steps: 4.1 The annual average flow Qo of each control section in different typical years y y Compared with the corresponding design flow, the flow ratio coefficient MCQ of the typical year y is derived y-p , establish the low water magnification ratio matrix MCS = {MCQ 1-p , MCQ y-p , MCQ Y-p }, Y is the total number of typical years; 4.2 Design low-flow flow TOS-Qs based on the total outlet section TOS of the basin p To control, according to the typical year y same multiple coefficient TOS-MCQ y-p Amplify and deduce the flow process of other control sections to form the overall low-flow design process set DDPS with a typical year y frequency p yp : Among them, DDP i is the design flow process sequence of section i in a typical year y with frequency p, is the flow observation value of the tth period at the i-th section, The flow rate of the i-th section in the t-th period of the typical year y frequency p; The interval flow of the ith section in the tth period, is the flow rate of the sth upstream section of the ith section at the tth period; Step 5 specifically includes: for the overall low-flow design composition process of each frequency in different typical years, repeat step 3.1 to analyze and calculate the spatiotemporal distribution of water shortages of each frequency in the basin in different typical years, analyze the long series of water shortages of the control sections step by step from the upstream, analyze and calculate the incoming flow sequence TST-IF, the downstream flow sequence TST-DF, the interval water shortage flow sequence TST-ISF and the cumulative water shortage flow sequence TST-CSF of each control section, and then construct the water shortage information matrix YPWSM of each frequency in different typical years: Among them, y_p_Qi t is the inflow volume at frequency p in period t in a typical year, y_p_Qd t is the discharge flow at frequency p in period t in a typical year, y_p_Qis t is the interval water shortage flow at the tth period of the y-frequency p period in a typical year, y_p_Qcs t is the cumulative water shortage flow in the tth period of frequency p in a typical year y; is the discharge flow of the sth upstream section at the tth period of the typical year y frequency p, is the cumulative water shortage flow of the sth upstream section in the tth period of the typical year y frequency p, and S is the number of sections upstream of the control section; Step 6 includes the following sub-steps: 6.1 Divide K sub-regions SP with reservoirs as nodes, clarify the control sections SPCS within the sub-region and the cascade reservoir groups SPCR above the sub-region; according to the design results of the cascade reservoir group, extract the normal water level NWL, dead water level DWL, flood limit water level FLL, available storage capacity RS, sub-region storage capacity coefficient set PCC and water level storage capacity curve SCC of each reservoir, and establish the water level storage capacity information set CR-LCIS of the cascade reservoir group in the basin: Among them, NWL j is the normal water level of the jth reservoir, DWL j is the dead water level of the jth reservoir, FLL j is the flood limit water level of the jth reservoir, RS j is the available storage capacity of the jth reservoir, PCC j is the partition capacity coefficient set of the jth reservoir, SCC j is the water level and storage capacity curve of the jth reservoir; PcC k is the storage capacity coefficient of the jth reservoir in partition k, RS b is the available storage capacity of the bth reservoir upstream of partition k, B is the number of reservoirs upstream of partition k; j is the water level of the jth reservoir, w j is the water level z of the jth reservoir j The corresponding storage capacity; f(z j ,w j ) is the water level z j With Ku Rong j Curve function, positive function f() uses reservoir capacity to calculate water level, f -1 () The reservoir capacity is calculated based on the water level, where R is the number of reservoirs in the cascade reservoir group; 6.2 Using the interval water shortage flow sequence TST-ISF of the control section SPCS in the sub-district, the sub-district cumulative water shortage time sequence PCWS of each frequency in different typical years of each sub-district is summed up to form the water shortage time sequence set SP_WSS of each frequency in different typical years of the sub-district: Among them, y_p_Qscs k_t is the interval cumulative water shortage flow in the tth period of the typical year y frequency p of the kth interval, and K is the total number of intervals; is the interval water shortage flow of the mth section in the kth interval in the typical year y frequency p tth period, M is the number of control sections in the kth interval; 6.3 For different typical water shortage processes of different frequencies, starting from the most downstream sub-district, the accumulated water shortage of the sub-district is used as the sub-district drought-resistant water source reserve storage capacity (PDC) that needs to be reserved for the cascade reservoir group SPCR above the sub-district. k , using the storage capacity coefficient PCc of the upstream reservoir in the sub-region k As the allocation coefficient, the sub-district cumulative water shortage schedule is allocated to each reservoir as the sub-drought-resistant water source storage capacity sequence SDCS that the reservoir needs to bear in the sub-district; on this basis, the sub-drought-resistant water source storage capacity sequences that each reservoir needs to bear are accumulated and summed to obtain the drought-resistant water source storage capacity reservation schedule DSSC of each reservoir; taking the flood limit water level as the water level value at the end of the scheduling period, it is accumulated in reverse order from the end of the scheduling period to the beginning of the scheduling period to obtain the corresponding water level sequence SP-DSSL of the drought-resistant water source storage capacity of each reservoir. On this basis, the drought-resistant water source storage capacity DRCL of the basin cascade reservoir group corresponding to different typical frequencies is formed; 2. The drought-resistant water source reserve design method for a reservoir group with different low water levels and compositions as claimed in claim 1, characterized in that: Control sections include river basins, key regional water supply guarantee sections, main and tributary water resource control sections, and water conservancy and hydropower project sections. If there are hydrological stations near the upstream and downstream of the control section, the hydrological process can be directly analyzed and calculated using hydrological observation data. If there is no hydrological observation section upstream or downstream, the hydrological analogy method is used to infer the hydrological process of the section.

3. The drought-resistant water source reserve design method for reservoirs of different low water levels and compositions as claimed in claim 1, characterized in that: The frequency P is selected according to the design requirements and in accordance with the provisions of the "Specifications for Hydrological Calculations of Water Conservancy and Hydropower Projects". If there is no existing design value for the control section CC, the analysis and calculation shall be carried out in accordance with the methods specified in the "Specifications for Hydrological Calculations of Water Conservancy and Hydropower Projects".

4. The drought-resistant water source reserve design method for a reservoir group with different low water levels and compositions as claimed in claim 1, characterized in that: In step 6.1, the reservoir capacity between the positive water level and the lowest operable water level is used. The lowest operable water level selects the flood limit water level or the dead water level. For special characteristic water level parameters such as the extreme dead water level and the extreme drawdown water level, they are selected according to the actual situation and included in the CR-LCIS.

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