CN116433003A - Drought and flood event evaluation and prediction method - Google Patents
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Abstract
The invention discloses a drought and waterlogging event evaluation and prediction method, which belongs to the technical field of hydrology and comprises the following steps: constructing a watershed WEP distributed hydrological model based on meteorological hydrological data and meteorological element daily scale data of the watershed calendar year; obtaining historical water supply capacity, historical ecological water demand, future water supply capacity and future ecological water demand in the river basin based on the river basin WEP distributed hydrological model; obtaining a corrected water resource surplus and deficit index; obtaining drought and waterlogging quantitative evaluation and grading results in the flow field; verifying a drought and flood grade dividing table to obtain a drought and flood evaluation system; based on a drought and waterlogging evaluation system, obtaining a historical drought and waterlogging event time-space evolution evaluation result in a river basin and a drought and waterlogging event time-space evolution result in different climates in the future, and completing future drought and waterlogging event estimation based on regional supply and demand water balance and river channel hydrologic situation; the invention solves the problems of insufficient consideration and insufficient prediction accuracy of the elements of the existing drought and waterlogging risk assessment and prediction method.
Description
Technical Field
The invention belongs to the technical field of hydrology, and particularly relates to a drought and waterlogging event evaluation and prediction method based on regional supply and demand water balance and river hydrologic situation.
Background
Weather anomalies due to climate change and human activity are a major cause of the frequency of drought and flood events, and are manifested by spatial-temporal heterogeneity of water supply and demand balance over localized areas. The drought and waterlogging comprehensive evaluation system is used for researching the space-time evolution characteristics, driving mechanism and risk evaluation of the past drought and waterlogging of the area and rationality of comprehensive coping strategies. Up to the present, the development of drought and waterlogging evaluation systems has undergone the germination period taking meteorological hydrologic variables as main characterization factors, the growth period taking multi-factor comprehensive characterization of water circulation key elements and the like, and the development period of diversified evaluation by means of 3S technology, hydrologic models and the like. The cognition about drought and waterlogging risks is gradually changed from two factors comprising dangers and vulnerability to four factors comprising exposure, sensitivity, vulnerability and bearing toughness, and the connotation and research of a drought and waterlogging evaluation system are continuously and deeply expanded.
The drought and waterlogging risk assessment and prediction method based on multiple climatic change situations is mainly characterized in that future meteorological elements are estimated through a climatic mode, and the prediction of a drought and waterlogging event in a future area is carried out through a drought and waterlogging index; the other is to analyze the response of the river basin vegetation and the crop growth process under the climate change background by combining a hydrologic model with a crop growth model, but the two methods lack scientificity based on regional moisture balance and river channel hydrologic situation and considering the influence of rainfall change, coverage, duration time and the like on drought and waterlogging, and verify the evaluation mode by historical drought and waterlogging events.
Disclosure of Invention
Aiming at the defects in the prior art, the drought and waterlogging event evaluation and prediction method provided by the invention is used for evaluating the historical drought and waterlogging event and predicting the future drought and waterlogging event based on the regional supply and demand water balance and the river hydrologic situation, and solves the problems of insufficient consideration and insufficient prediction accuracy of elements of the existing drought and waterlogging risk evaluation and prediction method.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
the invention provides a drought and waterlogging event evaluation and prediction method, which comprises the following steps of;
s1, constructing a drainage basin WEP distributed hydrological model based on meteorological hydrological data and meteorological element daily scale data of the drainage basin calendar year;
s2, obtaining historical water supply capacity and historical ecological water demand in the river basin based on a river basin WEP distributed hydrological model;
s3, obtaining future water supply capacity and future ecological water demand in the river basin based on the river basin WEP distributed hydrological model;
s4, obtaining a corrected water resource surplus and deficit index based on the historical water supply capacity, the historical ecological water demand, the future water supply capacity and the future ecological water demand in the river basin;
s5, obtaining drought and waterlogging quantitative evaluation and grading results in the flow domain based on the corrected water resource surplus and deficient index and the drought and waterlogging grading table;
S6, verifying a drought and waterlogging grade division table based on historical drought and waterlogging events in the river basin, historical drought and waterlogging evaluation and drought and waterlogging quantitative evaluation and grade division results in the river basin to obtain a drought and waterlogging evaluation system;
s7, based on a drought and waterlogging evaluation system, respectively calculating the cage area occupation ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the historical evaluation unit to obtain a time-space evolution evaluation result of the historical drought and waterlogging events in the river basin;
s8, based on the future water supply capacity, the future ecological water demand and the drought and waterlogging evaluation system in the river basin, the cage area ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the evaluation units under different climates in the future are calculated respectively, so that the time-space evolution result of the drought and waterlogging events in the river basin under different climates in the future is obtained, and the prediction of the future drought and waterlogging events based on the regional supply and demand water balance and the river channel hydrologic situation is completed.
The beneficial effects of the invention are as follows: according to the drought and waterlogging event evaluation and prediction method provided by the invention, regional meteorological hydrologic data are collected, a regional hydrologic model is constructed, parameter calibration is carried out, historical and future crop, forest land and grassland ecological water demand is obtained by combining a future meteorological mode, the water resource deficiency and the water resource surplus condition of the drainage basin history and the future annual month scale are calculated and quantized, then a drought and waterlogging index evaluation system is constructed, the rationality of the drought and waterlogging evaluation system is verified by using a historical document, and finally analysis and evaluation are carried out by utilizing the area, the occurrence frequency and the duration of the drought and waterlogging event in different drought and waterlogging grades in the future scene.
Further, the step S1 includes the steps of:
s11, obtaining the topography, soil, land utilization and meteorological hydrologic data of the river basin in the past year, and dividing the soil in the river basin into loam, clay soil and clay according to the WEP model input data requirement;
s12, based on the approach of weather and rainfall stations in the river basin, spatial spreading is carried out on weather element daily scale data according to a Thiessen polygon method;
s13, constructing an initial WEP distributed hydrologic model based on the topography, soil and land utilization of the river basin in the past year, meteorological hydrologic data and meteorological element daily scale data after spatial distribution;
s14, sliding T test is carried out on annual runoff change of the outlet section of the flow field, and the year of the mutation point is searched to obtain a preheating period, a periodic rate and a verification period of the WEP model;
s15, adjusting leaf area index, initial aquifer thickness, vegetation coverage, initial groundwater level, surface dryness and aerodynamic impedance coefficient in the initial WEP distributed hydrologic model based on the preheating period, the rate period and the verification period of the WEP model, calibrating the initial WEP distributed hydrologic model, and constructing the drainage basin WEP distributed hydrologic model by taking the correlation coefficient, the Nash coefficient and the relative error as evaluation indexes.
The beneficial effects of adopting the further scheme are as follows: a drainage basin WEP distributed hydrologic model is constructed based on the collected meteorological hydrologic data, and a foundation is provided for acquiring regional supply and demand water history and future data.
Further, the step S2 includes the steps of:
s21, obtaining a water circulation element process value based on a watershed WEP distributed hydrological model;
s22, obtaining average water supply capacity of each sub-basin in different months based on the water circulation element process value;
s23, acquiring a crop sowing date, a crop heat accumulation threshold value and a crop coefficient in a river basin, and acquiring an average length of a crop growing period based on average daily scale air temperature change data in the river basin and average water supply capacity of different months in each sub-river basin;
s24, obtaining the evaporation and transpiration amount in the river basin based on the hydrographic meteorological data of the past year and the Pengman calculation method;
s25, obtaining crop space distribution data based on evaporation capacity in the river basin, land utilization data and vegetation type data;
s26, calculating the water demand of the grid unit crops based on the crop space distribution data, the average length of the crop growing period and the crop coefficient;
s27, accumulating the crop water demand of the grid units to obtain the average crop water demand in each sub-river basin:
Wherein WD g Represents the average water demand of crops in the sub-watershed, and is mm; WD gi Represents the typical crop water demand of the ith grid unit, mm; s is S 0 Representing the area size of the grid cells; m is m 2 The method comprises the steps of carrying out a first treatment on the surface of the S represents the area of the sub-stream area, km 2 The method comprises the steps of carrying out a first treatment on the surface of the n represents the total number of grids in the substream domain;
s28, calculating the ecological water demand of the forest land and the grassland in the river basin based on the evaporation and transpiration in the river basin:
WD l ＝ET l ×K c ×K s
WD c ＝ET c ×K c ×K s
wherein WD l And WD c Respectively representing ecological water demand of the forest land and the grassland, and mm; ET (electric T) l And ET c Respectively representing reference transpiration of woodland and grassland, and mm; k (K) s Representing the soil moisture coefficient; s represents the actual soil moisture content; s is S w Indicating a soil withering point; s is S * Represents critical soil moisture content; k (K) c Representing vegetation coefficients, wherein the vegetation coefficients of the arbor, shrub and grassland are 0.62, 0.5385 and 0.263, respectively;
s29, obtaining the historical water supply capacity and the historical ecological water demand in the river basin based on the average water supply capacity of different months of each sub-river basin, the ecological water demand of the forests and grasslands in the river basin and the average water demand of the crops in each sub-river basin.
The beneficial effects of adopting the further scheme are as follows: based on the calibrated basin WEP distributed hydrologic model, the historical ecological water demand of crops, forests and grasslands on each evaluation unit is obtained, and data is provided for calculation of historical water resource surplus and deficient indexes of subsequent evaluation units.
Further, the step S3 includes the following steps:
s31, acquiring historical annual scale precipitation, air temperature, humidity, wind speed and radiation data of each greenhouse gas emission scene proposed by an IPCC sixth evaluation report, and integrating the historical annual scale precipitation, the air temperature, the humidity, the wind speed and the radiation data by using a BP neural network to obtain future meteorological element data sets under different emission scenes;
s32, inputting a future meteorological element data set into a watershed WEP distributed hydrological model, and simulating a water circulation element process value to obtain water supply variable data in the watershed in the future and in the year;
s33, repeating the steps S23 to S28 to obtain the ecological water demand of the future forests and grasslands in the watershed and the average water demand of the future crops in each sub-watershed;
s34, obtaining the future water supply capacity and the future ecological water demand in the river basin based on the data of the water supply capacity change in the past year and the year in the river basin, the ecological water demand of the future forests and grasslands in the river basin and the average water demand of the future crops in each sub-river basin.
The beneficial effects of adopting the further scheme are as follows: based on the calibrated basin WEP distributed hydrologic model, different climate modes are combined, ecological water demand of crops, forests and grasslands on each evaluation unit is estimated and obtained, and a data basis is provided for calculating future water resource profit and loss indexes of the evaluation units.
Further, the step S4 includes the steps of:
s41, calculating and obtaining the month-scale water supply amount of the evaluation unit based on the historical water supply amount in the river basin and the future water supply amount in the river basin:
WS＝P+ΔD-R-E α
ΔD＝D rise -D leakage
R＝R+R
o s
E α ＝E c +E e +E w
wherein WS represents the water supply amount mm of the evaluation unit; p represents the total precipitation amount of the evaluation unit, and mm; Δd represents the groundwater exchange amount, mm; r represents the total production flow of the slope surface, and mm; e (E) α Indicating the ineffective evaporation amount of the evaluation unit, mm; d (D) rise Represents the rising water amount, mm; d (D) leakage Represents the deep leakage amount, mm; r is R o Represents surface production flow, mm; r is R s Represents the flow in soil, mm; e (E) c Represents the evaporation capacity of the impermeable domain, mm; e (E) e Indicating the ineffective evaporation capacity among particles, mm; e (E) w Representing the evaporation capacity of a water area, and mm;
s42, calculating and obtaining the monthly scale water demand of the evaluation unit based on the historical ecological water demand in the river basin and the future ecological water demand in the river basin:
WD＝WD g +WD l +WD c
wherein WD represents the water demand of the evaluation unit, mm; WD g Representing the water demand of the cultivated land, and the thickness of the cultivated land is mm; WD l Represents the water demand of the forest land, mm; WD c Represents the water demand of grasslands, mm;
s43, calculating to obtain a month-scale water resource surplus and deficit index based on the month-scale water supply capacity of the evaluation unit and the month-scale water demand of the evaluation unit:
Z′＝K * ×ΔW
ΔW＝WS-WD
wherein Z' represents a month-scale water resource surplus and deficit index; k (K) * Representing an uncorrected water resource deficiency correction coefficient; Δw represents the difference in water supply and demand per month of the evaluation unit, and mm;
and->
Respectively representing the average water supply quantity of the research evaluation unit in corresponding months for a plurality of years and the average water demand quantity of the research evaluation unit in mm for a plurality of years;
s44, obtaining the water resource profit and loss amount of each evaluation unit in 12 months of most drought, and calculating to obtain extreme drought average weight based on month scale water resource profit and loss indexes:
wherein,,
representing extreme drought average weights; sigma Z represents the corresponding cumulative value of the water resource surplus and deficit indexes after 12 months of continuous extreme drought; />
Represents the water resource surplus and deficit of each evaluation unit for 12 months of drought, mm, where i' =1, 2, …,12;
s45, constructing a regression equation of extreme drought average weight and absolute values of average water supply capacity of the sub-watershed, average water demand of the sub-watershed and average water resource surplus and deficit, and obtaining a primary approximate value of a water resource surplus and deficit correction coefficient:
wherein K' represents a primary approximation of the water resource surplus and deficient correction coefficient in each sub-drainage basin;
represents the average water demand of the sub-river basin in months, and mm; />
Represents average water supply amount in a sub-river basin in mm; />
Representing absolute value of average water resource surplus and shortage of the sub-drainage basin, and mm;
S46, calculating to obtain a corrected water resource deficiency correction coefficient based on the average value of the absolute values of the deficiency and the deficiency of the water resources of the sub-watershed for many months, the average value of the absolute values of the deficiency and deficiency correction coefficient of the water resources of the watershed for many months:
wherein K is * ' represents a corrected water resource surplus and deficit correction coefficient; a represents the average value of absolute values of the surplus and deficit of the average water resource in the flow field for many months, and mm;
the average value of absolute values of the surplus and deficit of the average water resource in each month of the sub-river basin is expressed as mm; k (K) i "represents a first approximation of the sub-basin water resource surplus-deficit correction factor, where i' =1, 2, …,12;
s47, obtaining a corrected water resource profit and loss index based on the corrected water resource profit and loss correction coefficient:
Z＝K * ′×ΔW
wherein Z represents the modified water resource surplus and deficit index.
The beneficial effects of adopting the further scheme are as follows: based on the historical water supply capacity, the historical ecological water demand in the river basin, the future water supply capacity and the future ecological water demand in the river basin, namely the water demand of crops, forests and grasslands, the water resource surplus and deficient index is calculated according to the month scale, and a foundation is provided for the calculation and grading of the water resource evaluation index.
Further, the step S5 includes the steps of:
S51, constructing and determining a model of relation between the drought and waterlogging index, the water resource surplus and deficit accumulation value and the duration time based on the corrected water resource surplus and deficit index and the relation between the water resource surplus and deficit and the duration time:
wherein FDI i Drought and flood index representing month i; z is Z t A water resource surplus and deficit index indicating the t month;
s52, obtaining a corrected drought and waterlogging index based on a relation model of determining the drought and waterlogging index, the water resource surplus and deficient accumulation value and the duration time:
wherein FDI i″ 'represents the corrected drought index for month i'; r is R i″ Represents the outlet flow of the sub-basin of the ith month, m 3 ；
Mean value of runoff of ith month in statistical period for years, m 3 ；
And S53, grading the historical and future drought and waterlogging in the flow domain on the annual scale and the month scale based on the corrected drought and waterlogging index and the corrected drought and waterlogging grade grading table, and obtaining the quantized evaluation and grading result of the drought and waterlogging in the flow domain.
The beneficial effects of adopting the further scheme are as follows: based on the corrected water resource surplus and deficient index, the drought and flood index capable of representing the water resource evaluation index is calculated, and the grade division is performed based on the drought and flood index, so that a foundation is provided for verification and evaluation of a drought and flood system.
Further, the step S7 includes the steps of:
S71, calculating to obtain the cage area occupation ratio of the drought and waterlogging events of different grades of the historical evaluation unit based on the drought and waterlogging evaluation system:
wherein S is k Representing the coverage area ratio of the k-level drought and flood event; n' represents the total number of evaluation units for which k-level drought and flood events occur; a is that j Indicating the area of the j evaluation unit, km 2 ；A T Representing the total area of the river basin, km 2 ；
S72, calculating to obtain occurrence probabilities of drought and waterlogging events of different grades of historical evaluation units based on a drought and waterlogging evaluation system:
wherein F is k Representing the occurrence probability of k-level drought and flood events; n is n k Representing the month number of the k-level drought and flood event in the statistical time period; n' represents the total month number of the drought and flood event statistics period;
s73, calculating to obtain the duration time of the drought and flood events of different grades of the historical evaluation unit based on the drought and flood evaluation system:
wherein T is k Representing the average duration of k-level drought and flood events, and month; n' represents the total number of occurrences of k-level drought and flood events; t (T) j′ Representing the duration of the j' th drought/flood event, month;
s74, based on the cage area ratio, the occurrence probability and the duration of the historical evaluation unit drought and waterlogging events of different grades, the time-space evolution evaluation result of the historical drought and waterlogging events in the river basin is obtained.
The beneficial effects of adopting the further scheme are as follows: based on the drought and flood evaluation system, the drought and flood events which have appeared historically are subjected to multiple disc analysis and evaluation from the area, duration and occurrence frequency of the drought and flood cages.
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FIG. 1 is a flow chart of the steps of a method for evaluating and predicting drought and flood events according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
As shown in FIG. 1, in one embodiment of the present invention, the present invention provides a drought/flood event evaluation and prediction method, comprising the steps of;
s1, constructing a drainage basin WEP distributed hydrological model based on meteorological hydrological data and meteorological element daily scale data of the drainage basin calendar year;
the step S1 includes the steps of:
s11, obtaining the topography, soil, land utilization and meteorological hydrologic data of the river basin in the past year, and dividing the soil in the river basin into loam, clay soil and clay according to the WEP model input data requirement;
the meteorological hydrologic data obtained in the embodiment are mainly hydrologic data such as precipitation, air temperature and the like between 1950 and 2022 in the history of a research area, real rivers of the river basin are drawn by using Google Earth real-time remote sensing images, DEM is burnt by using a hand-drawn river network, the DEM is corrected, the ARCGIS is utilized to divide the river basin into 29 sub-basins in total, land utilization data in the two stages of 1980 and 2000 are utilized, and land utilization of the river basin is reclassified into ploughing, forests, grasses, water areas, construction sites, bare lands and the like; reclassifying Sihe river basin soil types into loam by referring to a Chinese soil database: sandy loam, loam and silty loam; sticking soil: sandy loam and loam; clay, and the like. Selecting 3 weather stations and 7 rainfall stations close to a Si river basin, and performing spatial spreading on the daily scale data of key weather elements such as precipitation, air temperature and the like of the weather stations 1963-2015 by using a Thiessen polygon method to serve as input of a model calculation unit;
S12, based on the approach of weather and rainfall stations in the river basin, spatial spreading is carried out on weather element daily scale data according to a Thiessen polygon method;
s13, constructing an initial WEP distributed hydrologic model based on the topography, soil and land utilization of the river basin in the past year, meteorological hydrologic data and meteorological element daily scale data after spatial distribution;
s14, sliding T test is carried out on annual runoff change of the outlet section of the flow field, and the year of the mutation point is searched to obtain a preheating period, a periodic rate and a verification period of the WEP model;
in the embodiment, taking the natural annual and monthly runoff process after Sihe river basin bookstore stations 1968 to 2015 are restored as a calibration target, according to the principle that annual runoff is matched firstly, the runoff is matched secondly, the runoff quantity is matched firstly, the runoff quantity is matched secondly, the runoff yield value is matched firstly, the model parameters are regulated according to an automatic optimization and manual trial-and-error combination mode based on the physical meaning of the model parameters and the influence of the model parameters on the rainfall-runoff process, wherein the rainfall and the runoff change of the river basin are comprehensively considered by possible mutation points, and the model rate period and the verification period are determined;
s15, adjusting leaf area index, initial aquifer thickness, vegetation coverage, initial groundwater level, surface dryness and aerodynamic impedance coefficient in an initial WEP distributed hydrological model based on a preheating period, a rate period and a verification period of the WEP model, calibrating the initial WEP distributed hydrological model, and constructing a drainage basin WEP distributed hydrological model by taking a correlation coefficient, a Nash coefficient and a relative error as evaluation indexes;
In this embodiment, the simulated flow value and the measured flow value satisfy R 2 ≥0.8&NSE≥0.7&RE is less than or equal to 0.05, wherein R 2 Representing the correlation coefficient, NSE representing the nash coefficient, RE representing the relative error;
in the embodiment, hydrologic data adopts a method of uniquely controlling natural year and month scale runoff processes from a hydrologic station bookstore station 1968 to 2015 in a river basin to carry out model calibration and verification, and the annual scale actual measurement and simulated runoff R of the periodic period and verification period of the rate 2 Above 0.83, NSE and RE are 0.72 and 0.67 respectively; month scale actual measurement and simulated runoff quantity R 2 Beyond 0.88, nse and RE are 0.73 and 0.79, respectively.
S2, obtaining historical water supply capacity and historical ecological water demand in the river basin based on a river basin WEP distributed hydrological model;
the step S2 includes the steps of:
s21, obtaining a water circulation element process value based on a watershed WEP distributed hydrological model;
s22, obtaining average water supply capacity of each sub-basin in 1950 to 2022 in different months based on the water circulation element process value;
in the embodiment, for the whole river basin, the average water supply amount of the Sihe river basin in 1968-2015 is 511.3mm for many years, and the average water precipitation amount of the Sihe river basin in many years is 73.9%, the distribution of the Sihe river basin in many years is uneven, the Sihe river basin is mainly concentrated in 6-9 months, and the Sihe river basin in many years can supply water for 73.6% of the Sihe river basin in all years. Wherein, the maximum water supply amount of the 7-month basin reaches 145.1mm and accounts for 28.3% of the annual water supply amount;
S23, acquiring a crop sowing date, a crop heat accumulation threshold value and a crop coefficient in a river basin, and obtaining the average length of the crop growing period in 1950 to 2022 based on average daily scale air temperature change data in the river basin and average water supply of different months in each sub-river basin;
in the embodiment, sihe river basin crops mainly comprise winter wheat and summer corn, and the sowing date of the winter wheat is generally from 9 late to ten early months; the sowing date of summer corns is the sowing date of winter wheat in the last and middle ten days of June, and the date that the average air temperature is 15-18 ℃ for the first time in the last ten days of 9 months is used as the sowing date of winter wheat; the suitable sowing temperature of summer corns is 20-25 ℃, the date when the average air temperature is 20-25 ℃ for the first time in the last ten days of June is used as the sowing date of summer corns, the growth period length of winter wheat in Sihe river basin is 220-250d, and the growth period length of summer corns is about 80 d;
s24, obtaining the evaporation and transpiration amount in the river basin based on the hydrographic meteorological data of the past year and the Pengman calculation method;
s25, obtaining crop space distribution data based on evaporation capacity in the river basin, land utilization data and vegetation type data;
s26, calculating the water demand of the grid unit crops based on the crop space distribution data, the average length of the crop growing period and the crop coefficient;
S27, accumulating the crop water demand of the grid units to obtain the average crop water demand in each sub-river basin:
wherein WD g Represents the average water demand of crops in the sub-watershed, and is mm; WD gi Represents the typical crop water demand of the ith grid unit, mm; s is S 0 Representing the area size of the grid cells; m is m 2 The method comprises the steps of carrying out a first treatment on the surface of the S represents the area of the sub-stream area, km 2 The method comprises the steps of carrying out a first treatment on the surface of the n represents the total number of grids in the substream domain;
in the embodiment, 1968 to 2015, the average water demand of crops in a river basin for years is 352.1mm, and the average water demand for crops for years is 50.9 percent;
s28, calculating the ecological water demand of the forest land and the grassland in the river basin based on the evaporation and transpiration in the river basin:
WD l ＝ET l ×K c ×K s
WD c ＝ET c ×K c ×K s
wherein WD l And WD c Respectively representing ecological water demand of the forest land and the grassland, and mm; ET (electric T) l And ET c Respectively representing reference transpiration of woodland and grassland, and mm; k (K) s Representing the soil moisture coefficient; s represents the actual soil moisture content; s is S w Indicating a soil withering point; s is S * Represents critical soil moisture content; k (K) c Representing vegetation coefficients, wherein the vegetation coefficients of the arbor, shrub and grassland are 0.62, 0.5385 and 0.263, respectively;
s29, obtaining the historical water supply capacity and the historical ecological water demand in the river basin based on the average water supply capacity of different months of each sub-river basin, the ecological water demand of the forests and grasslands in the river basin and the average water demand of the crops in each sub-river basin.
In the embodiment, the average water supply amount of the Sihe river basin in 1968-2015 for many years is 511.3mm, which accounts for 73.9% of the average precipitation amount for many years;
s3, obtaining future water supply capacity and future ecological water demand in the river basin based on the river basin WEP distributed hydrological model;
the step S3 includes the steps of:
s31, acquiring historical annual scale precipitation, air temperature, humidity, wind speed and radiation data of each greenhouse gas emission scene proposed by an IPCC sixth evaluation report, and integrating the historical annual scale precipitation, the air temperature, the humidity, the wind speed and the radiation data by using a BP neural network to obtain future meteorological element data sets under different emission scenes;
in the embodiment, 5 sets of global climate patterns RCP2.6, RCP4.5 and RCP8.5 after ISI-MIP is corrected by bilinear interpolation and statistical deviation are used as supports, and the river basin drought and waterlogging event space-time change under the future climate change condition is estimated; climate pattern usage data including 1968 to 2050 day scale precipitation, air temperature, average relative humidity, wind speed, total solar radiation, etc., with a spatial resolution of 0.5 ° ×0.5 °;
s32, inputting a future meteorological element data set into a watershed WEP distributed hydrological model, and simulating a water circulation element process value to obtain water supply variable data in the watershed in the future and in the year;
S33, repeating the steps S23 to S28 to obtain the ecological water demand of the future forests and grasslands in the watershed and the average water demand of the future crops in each sub-watershed;
in the embodiment, model integration is performed through a BP neural network, and future meteorological element data sets of different emission scenes are established; three emission conditions of RCP2.6, RCP4.5 and RCP8.5, the average value of the total water demand of the river basin in the future 2020-2050 years is increased by 9.6%, 9.9% and 9.8% respectively compared with the average value of the total water demand of the river basin in the history 1968-2015 years;
s34, obtaining the future water supply capacity and the future ecological water demand in the river basin based on the data of the water supply capacity change in the past year and the year in the river basin, the ecological water demand of the future forests and grasslands in the river basin and the average water demand of the future crops in each sub-river basin.
S4, obtaining a corrected water resource surplus and deficit index based on the historical water supply capacity, the historical ecological water demand, the future water supply capacity and the future ecological water demand in the river basin;
the step S4 includes the steps of:
s41, calculating and obtaining the month-scale water supply amount of the evaluation unit based on the historical water supply amount in the river basin and the future water supply amount in the river basin:
WS＝P+ΔD-R-E α
ΔD＝D rise -D leakage
R＝R+R
o s
E α ＝E c +E e +E w
wherein WS represents the water supply amount mm of the evaluation unit; p represents the total precipitation amount of the evaluation unit, and mm; Δd represents the groundwater exchange amount, mm; r represents the total production flow of the slope surface, and mm; e (E) α Representing an evaluation sheetIneffective evaporation capacity, mm; d (D) rise Represents the rising water amount, mm; d (D) leakage Represents the deep leakage amount, mm; r is R o Represents surface production flow, mm; r is R s Represents the flow in soil, mm; e (E) c Represents the evaporation capacity of the impermeable domain, mm; e (E) e Indicating the ineffective evaporation capacity among particles, mm; e (E) w Representing the evaporation capacity of a water area, and mm;
s42, calculating and obtaining the monthly scale water demand of the evaluation unit based on the historical ecological water demand in the river basin and the future ecological water demand in the river basin:
WD＝WD g +WD l +WD c
wherein WD represents the water demand of the evaluation unit, mm; WD g Representing the water demand of the cultivated land, and the thickness of the cultivated land is mm; WD l Represents the water demand of the forest land, mm; WD c Represents the water demand of grasslands, mm;
s43, calculating to obtain a month-scale water resource surplus and deficit index based on the month-scale water supply capacity of the evaluation unit and the month-scale water demand of the evaluation unit:
Z′＝K * ×ΔW
ΔW＝WS-WD
wherein Z' represents a month-scale water resource surplus and deficit index; k (K) * Representing an uncorrected water resource deficiency correction coefficient; Δw represents the difference in water supply and demand per month of the evaluation unit, and mm;
and->
Respectively representing the average water supply quantity of the research evaluation unit in corresponding months for a plurality of years and the average water demand quantity of the research evaluation unit in mm for a plurality of years;
s44, obtaining the water resource profit and loss amount of each evaluation unit in 12 months of most drought, and calculating to obtain extreme drought average weight based on month scale water resource profit and loss indexes:
Wherein,,
representing extreme drought average weights; sigma Z represents the corresponding cumulative value of the water resource surplus and deficit indexes after 12 months of continuous extreme drought; />
Represents the water resource surplus and deficit of each evaluation unit for 12 months of drought, mm, where i' =1, 2, …,12;
s45, constructing a regression equation of extreme drought average weight and absolute values of average water supply capacity of the sub-watershed, average water demand of the sub-watershed and average water resource surplus and deficit, and obtaining a primary approximate value of a water resource surplus and deficit correction coefficient:
wherein K' represents a primary approximation of the water resource surplus and deficient correction coefficient in each sub-drainage basin;
represents the average water demand of the sub-river basin in months, and mm; />
Represents average water supply amount in a sub-river basin in mm; />
Representing absolute value of average water resource surplus and shortage of the sub-drainage basin, and mm;
s46, calculating to obtain a corrected water resource deficiency correction coefficient based on the average value of the absolute values of the deficiency and the deficiency of the water resources of the sub-watershed for many months, the average value of the absolute values of the deficiency and deficiency correction coefficient of the water resources of the watershed for many months:
wherein K is * ' represents a corrected water resource surplus and deficit correction coefficient; a represents the average value of absolute values of the surplus and deficit of the average water resource in the flow field for many months, and mm; 
The average value of absolute values of the surplus and deficit of the average water resource in each month of the sub-river basin is expressed as mm; k (K) i "represents a first approximation of the sub-basin water resource surplus-deficit correction factor, where i' =1, 2, …,12;
s47, obtaining a corrected water resource profit and loss index based on the corrected water resource profit and loss correction coefficient:
Z＝K * ′×ΔW
wherein Z represents the modified water resource surplus and deficit index;
s5, obtaining drought and waterlogging quantitative evaluation and grading results in the flow domain based on the corrected water resource surplus and deficient index and the drought and waterlogging grading table;
the step S5 includes the steps of:
s51, constructing and determining a model of relation between the drought and waterlogging index, the water resource surplus and deficit accumulation value and the duration time based on the corrected water resource surplus and deficit index and the relation between the water resource surplus and deficit and the duration time:
wherein FDI i Drought and flood index representing month i; z is Z t A water resource surplus and deficit index indicating the t month;
s52, obtaining a corrected drought and waterlogging index based on a relation model of determining the drought and waterlogging index, the water resource surplus and deficient accumulation value and the duration time:
wherein FDI i″ 'represents the corrected drought index for month i'; r is R i″ Represents the outlet flow of the sub-basin of the ith month, m 3 ；
Mean value of runoff of ith month in statistical period for years, m 3 ；
S53, grading the historical and future drought and waterlogging in the flow domain on the annual scale and the monthly scale based on the corrected drought and waterlogging index and the corrected drought and waterlogging grade grading table to obtain the quantized evaluation and grading result of the drought and waterlogging in the flow domain;
the drought and flood level classification table is shown in table 1:
TABLE 1
| Drought and flood index FDI | Grade |
| FDI≥4.0 | Extreme flood |
| 3.0≤FDI<4.0 | Severe flooding |
| 2.0≤FDI<3.0 | Moderate flooding |
| 1.0≤FDI<2.0 | Light flood |
| -1.0<FDI≤1.0 | Normal state |
| -2.0<FDI≤-1.0 | Mild drought |
| -3.0<FDI≤-2.0 | Moderate drought |
| -4.0<FDI≤-3.0 | Severe drought |
| FDI≤-4.0 | Extreme drought |
S6, verifying a drought and waterlogging grade division table based on historical drought and waterlogging events in the river basin, historical drought and waterlogging evaluation and drought and waterlogging quantitative evaluation and grade division results in the river basin to obtain a drought and waterlogging evaluation system;
in this embodiment, the actual drought and flood disaster conditions in 1968-2000 of the recording research area of "Chinese weather disaster dictionary and Shandong Jiu" are taken as references, and the rationality of dividing drought and flood grades by the calculation indexes is verified, and according to the recording result of "Chinese weather disaster dictionary"), the drought condition is: serious drought occurs in the flood season of 7-8 months in Shandong province in 1979. 8 months, the precipitation amount is only 74mm, 54% less than the perennial synchronization, and the total province is 120 tens of thousands of hectares due to drought disaster area; in 1981-1983, shandong province (Sihe in China) had been a three-year continuous drought; fringed monster (14. Sub. Watershed) extra-large drought in 1983; two consecutive drought states occur in Shandong province (Sichuan river in 1988-1989), wherein fright drought of Qufu (14 th sub-river basin) in 1988, precipitation of 17.8mm in 9-11 months and wheat seeding difficulty of 1.3 hectare are achieved; in addition, in 1989, the whole province encounters the history of extremely drought, and the research area Sihe starts to cut off from the autumn of 1988; flood conditions: in 7 months 1993, jining city even drops to extremely heavy storm, the area of accumulated water in the farmland of the whole city reaches 35.5 ten thousand hectares, 627 villages are flooded; the typical area, the Zhou City (16 th sub-basin), had a rainfall of more than 300mm. The drought and waterlogging index evaluation result is compared and analyzed, so that the drought and waterlogging event can be effectively represented;
S7, based on a drought and waterlogging evaluation system, respectively calculating the cage area occupation ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the historical evaluation unit to obtain a time-space evolution evaluation result of the historical drought and waterlogging events in the river basin;
the step S7 includes the steps of:
s71, calculating to obtain the cage area occupation ratio of the drought and waterlogging events of different grades of the historical evaluation unit based on the drought and waterlogging evaluation system:
wherein S is k Representing the coverage area ratio of the k-level drought and flood event; n' represents the total number of evaluation units for which k-level drought and flood events occur; a is that j Indicating the area of the j evaluation unit, km 2 ；A T Representing the total area of the river basin, km 2 ；
In this example, the actual drought event coverage area ratio of Siriver basin at the actual time and above is in a decreasing trend, and the annual change rate is-0.52%/a (-13.6 km) 2 A); wherein, the drought shrouding area ratio in 1988 is the largest and reaches 93.1%, and the shrouding area ratio of the flooding event in the slight and above river basin is smaller than the drought; in the actual measurement period, the area ratio of the flood cage is in an increasing trend, and the annual change rate is 0.37%/a (9.7 km) 2 A), wherein, the area of the flood cage in 1984 is the largest, which reaches 48.3%;
s72, calculating to obtain occurrence probabilities of drought and waterlogging events of different grades of historical evaluation units based on a drought and waterlogging evaluation system:
Wherein F is k Representing the occurrence probability of k-level drought and flood events; n is n k Representing the month number of the k-level drought and flood event in the statistical time period; n' represents the statistics of drought and waterlogging eventsTotal number of months of the segment;
in the embodiment, the drought occurrence frequency of Sihe river basin in No. 11-14 plain in northwest of the river basin exceeds 60%; the occurrence frequency of severe drought and drought above the Siriver basin is changed within the range of 2-39%, and the spatial distribution is consistent with slight drought and drought above the Siriver basin;
s73, calculating to obtain the duration time of the drought and flood events of different grades of the historical evaluation unit based on the drought and flood evaluation system:
wherein T is k Representing the average duration of k-level drought and flood events, and month; n' represents the total number of occurrences of k-level drought and flood events; t (T) j′ Representing the duration of the j' th drought/flood event, month;
in this embodiment, the duration of drought or flood is substantially consistent with the trend of frequency of occurrence from the spatial distribution, wherein the average duration of drought events gradually decreases from north to south, the average duration of drought in the northwest subzone of the river basin is more than 10 months, the average duration of drought in the severe subzone of the river basin is more than 3 months, and the average duration of drought in the southern mountain zone is less than 4 months and 1.5 months, respectively; in contrast, the average duration of Sihe river basin flooding gradually increases from north to south, the average duration of Sihe subbasin mild and superior flooding is less than 2 months, and no serious and superior flooding event occurs; the average duration of slight and more floods in the south mountain areas such as sub-watershed is about 4 months;
S74, acquiring a time-space evolution evaluation result of the historical drought and waterlogging event in the river basin based on the cage area occupation ratio, the occurrence probability and the duration of the historical evaluation unit of different levels of drought and waterlogging event;
s8, based on the future water supply capacity, the future ecological water demand and the drought and waterlogging evaluation system in the river basin, the cage area ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the evaluation units under different climates in the future are calculated respectively, so that the time-space evolution result of the drought and waterlogging events in the river basin under different climates in the future is obtained, and the prediction of the future drought and waterlogging events based on the regional supply and demand water balance and the river channel hydrologic situation is completed.
In this embodiment, compared with the estimated results of three emission situations in 1968-2015 of the actual measurement period, the estimated results of the three emission situations in the future 30 years include that the RCP2.6, RCP4.5 and RCP8.5 emission situations are that the drought cage area of the river basin is slightly and more than the average value of many years is respectively reduced by 34%, 28.5% and 39.1% compared with the actual measurement period of the average value of many years; the proportion of the serious drought cage area and the drought cage area is respectively reduced by 93.6%, 94% and 97.6%, the occurrence frequency of the serious drought and the drought of the grade above in most areas in the river basin in the future 30 years is slowed down compared with the actual measurement period of the history, and the maximum reduction reaches 90%; the average duration time change of Sihe river basin with different levels of drought is consistent with the relative change of the occurrence frequency of drought in the future 30 years, and the average duration time of the drought in the upstream area of the river basin is reduced slightly and above; wherein, the RCP8.5 emission scenario is more damped than RCP2.6 and RCP4.5, and the maximum damping is 68%.
Claims (7)
1. A drought and waterlogging event evaluation and prediction method is characterized by comprising the following steps of;
s1, constructing a drainage basin WEP distributed hydrological model based on meteorological hydrological data and meteorological element daily scale data of the drainage basin calendar year;
s2, obtaining historical water supply capacity and historical ecological water demand in the river basin based on a river basin WEP distributed hydrological model;
s3, obtaining future water supply capacity and future ecological water demand in the river basin based on the river basin WEP distributed hydrological model;
s4, obtaining a corrected water resource surplus and deficit index based on the historical water supply capacity, the historical ecological water demand, the future water supply capacity and the future ecological water demand in the river basin;
s5, obtaining drought and waterlogging quantitative evaluation and grading results in the flow domain based on the corrected water resource surplus and deficient index and the drought and waterlogging grading table;
s6, verifying a drought and waterlogging grade division table based on historical drought and waterlogging events in the river basin, historical drought and waterlogging evaluation and drought and waterlogging quantitative evaluation and grade division results in the river basin to obtain a drought and waterlogging evaluation system;
s7, based on a drought and waterlogging evaluation system, respectively calculating the cage area occupation ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the historical evaluation unit to obtain a time-space evolution evaluation result of the historical drought and waterlogging events in the river basin;
S8, based on the future water supply capacity, the future ecological water demand and the drought and waterlogging evaluation system in the river basin, the cage area ratio, the occurrence probability and the duration of different levels of drought and waterlogging events of the evaluation units under different climates in the future are calculated respectively, so that the time-space evolution result of the drought and waterlogging events in the river basin under different climates in the future is obtained, and the prediction of the future drought and waterlogging events based on the regional supply and demand water balance and the river channel hydrologic situation is completed.
2. The drought/flood event evaluation and prediction method according to claim 1, wherein the step S1 comprises the steps of:
s11, obtaining the topography, soil, land utilization and meteorological hydrologic data of the river basin in the past year, and dividing the soil in the river basin into loam, clay soil and clay according to the WEP model input data requirement;
s12, based on the approach of weather and rainfall stations in the river basin, spatial spreading is carried out on weather element daily scale data according to a Thiessen polygon method;
s13, constructing an initial WEP distributed hydrologic model based on the topography, soil and land utilization of the river basin in the past year, meteorological hydrologic data and meteorological element daily scale data after spatial distribution;
s14, sliding T test is carried out on annual runoff change of the outlet section of the flow field, and the year of the mutation point is searched to obtain a preheating period, a periodic rate and a verification period of the WEP model;
S15, adjusting leaf area index, initial aquifer thickness, vegetation coverage, initial groundwater level, surface dryness and aerodynamic impedance coefficient in the initial WEP distributed hydrologic model based on the preheating period, the rate period and the verification period of the WEP model, calibrating the initial WEP distributed hydrologic model, and constructing the drainage basin WEP distributed hydrologic model by taking the correlation coefficient, the Nash coefficient and the relative error as evaluation indexes.
3. The drought/flood event evaluation and prediction method according to claim 1, wherein the step S2 comprises the steps of:
s21, obtaining a water circulation element process value based on a watershed WEP distributed hydrological model;
s22, obtaining average water supply capacity of each sub-basin in different months based on the water circulation element process value;
s23, acquiring a crop sowing date, a crop heat accumulation threshold value and a crop coefficient in a river basin, and acquiring an average length of a crop growing period based on average daily scale air temperature change data in the river basin and average water supply capacity of different months in each sub-river basin;
s24, obtaining the evaporation and transpiration amount in the river basin based on the hydrographic meteorological data of the past year and the Pengman calculation method;
s25, obtaining crop space distribution data based on evaporation capacity in the river basin, land utilization data and vegetation type data;
S26, calculating the water demand of the grid unit crops based on the crop space distribution data, the average length of the crop growing period and the crop coefficient;
s27, accumulating the crop water demand of the grid units to obtain the average crop water demand in each sub-river basin:
wherein WD g Represents the average water demand of crops in the sub-watershed, and is mm; WD gi Represents the typical crop water demand of the ith grid unit, mm; s is S 0 Representing the area size of the grid cells; m is m 2 The method comprises the steps of carrying out a first treatment on the surface of the S represents the area of the sub-stream area, km 2 The method comprises the steps of carrying out a first treatment on the surface of the n represents the total number of grids in the substream domain;
s28, calculating the ecological water demand of the forest land and the grassland in the river basin based on the evaporation and transpiration in the river basin:
WD l ＝ET l ×K c ×K s
WD c ＝ET c ×K c ×K s
wherein WD l And WD c Respectively representing ecological water demand of the forest land and the grassland, and mm; ET (electric T) l And ET c Respectively representing reference transpiration of woodland and grassland, and mm; k (K) s Representing the soil moisture coefficient; s represents the actual soil moisture content; s is S w Indicating a soil withering point; s is S * Represents critical soil moisture content; k (K) c Representing vegetation coefficients, wherein the vegetation coefficients of the arbor, shrub and grassland are 0.62, 0.5385 and 0.263, respectively;
s29, obtaining the historical water supply capacity and the historical ecological water demand in the river basin based on the average water supply capacity of different months of each sub-river basin, the ecological water demand of the forests and grasslands in the river basin and the average water demand of the crops in each sub-river basin.
4. The drought/flood event evaluation and prediction method according to claim 3, wherein the step S3 comprises the steps of:
s31, acquiring historical annual scale precipitation, air temperature, humidity, wind speed and radiation data of each greenhouse gas emission scene proposed by an IPCC sixth evaluation report, and integrating the historical annual scale precipitation, the air temperature, the humidity, the wind speed and the radiation data by using a BP neural network to obtain future meteorological element data sets under different emission scenes;
s32, inputting a future meteorological element data set into a watershed WEP distributed hydrological model, and simulating a water circulation element process value to obtain water supply variable data in the watershed in the future and in the year;
s33, repeating the steps S23 to S28 to obtain the ecological water demand of the future forests and grasslands in the watershed and the average water demand of the future crops in each sub-watershed;
s34, obtaining the future water supply capacity and the future ecological water demand in the river basin based on the data of the water supply capacity change in the past year and the year in the river basin, the ecological water demand of the future forests and grasslands in the river basin and the average water demand of the future crops in each sub-river basin.
5. The drought/flood event assessment and prediction method according to claim 4, wherein the step S4 comprises the steps of:
S41, calculating and obtaining the month-scale water supply amount of the evaluation unit based on the historical water supply amount in the river basin and the future water supply amount in the river basin:
WS＝P+ΔD-R-E α
ΔD＝D rise -D leakage
R＝R+R
o s
E α ＝E c +E e +E w
wherein WS represents the water supply amount mm of the evaluation unit; p represents the total precipitation amount of the evaluation unit, and mm; Δd represents the groundwater exchange amount, mm; r represents the total production flow of the slope surface, and mm; e (E) α Indicating the ineffective evaporation amount of the evaluation unit, mm; d (D) rise Represents the rising water amount, mm; d (D) leakage Represents the deep leakage amount, mm; r is R o Represents surface production flow, mm; r is R s Represents the flow in soil, mm; e (E) c Represents the evaporation capacity of the impermeable domain, mm; e (E) e Indicating the ineffective evaporation capacity among particles, mm; e (E) w Representing the evaporation capacity of a water area, and mm;
s42, calculating and obtaining the monthly scale water demand of the evaluation unit based on the historical ecological water demand in the river basin and the future ecological water demand in the river basin:
WD＝WD g +WD l +WD c
wherein WD represents the water demand of the evaluation unit, mm; WD g Representing the water demand of the cultivated land, and the thickness of the cultivated land is mm; WD l Represents the water demand of the forest land, mm; WD c Represents the water demand of grasslands, mm;
s43, calculating to obtain a month-scale water resource surplus and deficit index based on the month-scale water supply capacity of the evaluation unit and the month-scale water demand of the evaluation unit:
Z′＝K * ×ΔW
ΔW＝WS-WD
wherein Z' represents a month-scale water resource surplus and deficit index; k (K) * Representing an uncorrected water resource deficiency correction coefficient; Δw represents the difference in water supply and demand per month of the evaluation unit, and mm; 
And->
Respectively representing the average water supply quantity of the research evaluation unit in corresponding months for a plurality of years and the average water demand quantity of the research evaluation unit in mm for a plurality of years;
s44, obtaining the water resource profit and loss amount of each evaluation unit in 12 months of most drought, and calculating to obtain extreme drought average weight based on month scale water resource profit and loss indexes:
wherein,,
representing extreme drought average weights; sigma Z represents the corresponding cumulative value of the water resource surplus and deficit indexes after 12 months of continuous extreme drought; />
Represents the water resource surplus and deficit of each evaluation unit for 12 months of drought, mm, where i' =1, 2, …,12;
s45, constructing a regression equation of extreme drought average weight and absolute values of average water supply capacity of the sub-watershed, average water demand of the sub-watershed and average water resource surplus and deficit, and obtaining a primary approximate value of a water resource surplus and deficit correction coefficient:
wherein K' represents a primary approximation of the water resource surplus and deficient correction coefficient in each sub-drainage basin;
represents the average water demand of the sub-river basin in months, and mm; />
Represents average water supply amount in a sub-river basin in mm; />
Representing absolute value of average water resource surplus and shortage of the sub-drainage basin, and mm;
s46, calculating to obtain a corrected water resource deficiency correction coefficient based on the average value of the absolute values of the deficiency and the deficiency of the water resources of the sub-watershed for many months, the average value of the absolute values of the deficiency and deficiency correction coefficient of the water resources of the watershed for many months:
Wherein K is *′ Representing a corrected water resource surplus and deficit correction coefficient; a represents the average value of absolute values of the surplus and deficit of the average water resource in the flow field for many months, and mm;
the average value of absolute values of the surplus and deficit of the average water resource in each month of the sub-river basin is expressed as mm; k (K) i′ 'represents a first approximation of the sub-basin water resource surplus-deficit correction factor, where i' =1, 2, …,12;
s47, obtaining a corrected water resource profit and loss index based on the corrected water resource profit and loss correction coefficient:
Z＝K *′ ×ΔW
wherein Z represents the modified water resource surplus and deficit index.
6. The drought/flood event assessment and prediction method according to claim 5, wherein step S5 comprises the steps of:
s51, constructing and determining a model of relation between the drought and waterlogging index, the water resource surplus and deficit accumulation value and the duration time based on the corrected water resource surplus and deficit index and the relation between the water resource surplus and deficit and the duration time:
wherein FDI i Drought and flood index representing month i; z is Z t A water resource surplus and deficit index indicating the t month;
s52, obtaining a corrected drought and waterlogging index based on a relation model of determining the drought and waterlogging index, the water resource surplus and deficient accumulation value and the duration time:
wherein FDI i″ 'represents the corrected drought index for month i'; r is R i″ Represents the outlet flow of the sub-basin of the ith month, m 3 ；
Mean value of runoff of ith month in statistical period for years, m 3 ；
And S53, grading the historical and future drought and waterlogging in the flow domain on the annual scale and the month scale based on the corrected drought and waterlogging index and the corrected drought and waterlogging grade grading table, and obtaining the quantized evaluation and grading result of the drought and waterlogging in the flow domain.
7. The drought/flood event assessment and prediction method according to claim 6, wherein step S7 comprises the steps of:
s71, calculating to obtain the cage area occupation ratio of the drought and waterlogging events of different grades of the historical evaluation unit based on the drought and waterlogging evaluation system:
wherein S is k Representing the coverage area ratio of the k-level drought and flood event; n' represents the total number of evaluation units for which k-level drought and flood events occur; a is that j Indicating the area of the j evaluation unit, km 2 ；A T Representing the total area of the river basin, km 2 ；
S72, calculating to obtain occurrence probabilities of drought and waterlogging events of different grades of historical evaluation units based on a drought and waterlogging evaluation system:
wherein F is k Representing the occurrence probability of k-level drought and flood events; n is n k Representing the month number of the k-level drought and flood event in the statistical time period; n' represents the total month number of the drought and flood event statistics period;
s73, calculating to obtain the duration time of the drought and flood events of different grades of the historical evaluation unit based on the drought and flood evaluation system:
Wherein T is k Representing the average duration of k-level drought and flood events, and month; n' represents the total number of occurrences of k-level drought and flood events; t (T) j′ Representing the duration of the j' th drought/flood event, month;
s74, based on the cage area ratio, the occurrence probability and the duration of the historical evaluation unit drought and waterlogging events of different grades, the time-space evolution evaluation result of the historical drought and waterlogging events in the river basin is obtained.
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| CN117473791A (en) * | 2023-12-22 | 2024-01-30 | 水发科技信息(山东)有限公司 | Public data storage management system based on artificial intelligence |
| CN118071538A (en) * | 2024-01-25 | 2024-05-24 | 珠江水利委员会珠江水利科学研究院 | Method, device, equipment and storage medium for generating adaptive strategy of dry-wet change |
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| CN117473791A (en) * | 2023-12-22 | 2024-01-30 | 水发科技信息(山东)有限公司 | Public data storage management system based on artificial intelligence |
| CN117473791B (en) * | 2023-12-22 | 2024-03-29 | 水发科技信息(山东)有限公司 | Public data storage management system based on artificial intelligence |
| CN118071538A (en) * | 2024-01-25 | 2024-05-24 | 珠江水利委员会珠江水利科学研究院 | Method, device, equipment and storage medium for generating adaptive strategy of dry-wet change |
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