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CN-122022298-A - Short-period drought and flood emergency identification method based on standardized moisture abnormality index

CN122022298ACN 122022298 ACN122022298 ACN 122022298ACN-122022298-A

Abstract

The invention discloses a short-period drought and flood emergency identification method based on a standardized moisture abnormality index, which comprises the steps of 1) collecting weather data of a research area over the years, 2) calculating potential evaporation PET (polyethylene terephthalate), 3) calculating weather proper precipitation of a month scale, 4) calculating a water balance value reflecting drought conditions of specific days, namely, early water deficiency WSD (wireless sensor device), 5) calculating accumulated probability P of early water deficiency, 6) carrying out Gaussian inverse transformation on the accumulated probability P to obtain the daily-scale standardized moisture abnormality index SZI, 7) determining drought, flood and drought and flood emergency identification and conversion thresholds according to the daily-scale standardized moisture abnormality index SZI, and 8) determining variation trends of drought, flood and drought and flood emergency by utilizing Kendel-delta analysis. The invention can accurately identify drought and waterlogging emergency, and provides an effective tool for disaster prevention and reduction.

Inventors

  • ZHANG GENGXI
  • YANG QIYUE
  • LIANG TAO
  • WANG HUIMIN
  • HUANG JINBAI

Assignees

  • 扬州大学
  • 江苏新地环境工程有限公司

Dates

Publication Date
20260512
Application Date
20260121

Claims (8)

  1. 1. A short-period drought and flood emergency identification method based on a standardized moisture abnormality index is characterized by comprising the following steps: 1) Collecting weather data of a research area over the years; 2) Calculating potential evaporative PET; 3) Calculating the appropriate precipitation of the climate of the month scale ; 4) Calculating a water quantity balance value reflecting the drought condition of a specific day, namely, the early water surplus and shortage WSD; 5) Calculating the accumulated probability P of the early water surplus and deficient; 6) Performing Gaussian inverse transformation on the accumulated probability P to obtain a daily-scale standardized moisture abnormality index SZI; 7) Determining drought, flood and drought and flood emergency identification and conversion thresholds according to a daily scale standardized moisture abnormality index SZI, and identifying drought, flood and drought and flood emergency events through a run-length theory; 8) And determining the change trend of the occurrence frequency, turning time and intensity of the drought and waterlogging sharp turn by utilizing Kendell analysis.
  2. 2. The method for identifying short-period drought and flood according to claim 1, wherein the step 2) comprises the steps of calculating potential evaporative PET according to Penman-Monteth formula: ; Wherein R n represents surface net radiation MJ m −2 day −1 , G represents soil heat flux MJ m −2 day −1 , and T represents air temperature of 2m Gao Duri ℃; The wind speed ms −1 ;e s representing 2m height represents saturated water vapor pressure, and e a represents actual water vapor pressure; shows the slope of saturated water vapor pressure curve, kPa -1 .
  3. 3. The method for identifying short-period drought and flood according to claim 1, wherein in step 3) the method specifically comprises the steps of The calculation formula is as follows: ; Wherein PET represents potential evaporation, PR represents potential water replenishment, PRO represents potential yield, PL represents potential loss, parameters alpha j 、β j 、γ j , The influence weights of the potential evaporation PET, the potential water supplementing quantity PR, the potential yield PRO and the potential loss quantity PL are respectively given; four parameters alpha j 、β j 、γ j in the formula, Calculated from the following formula: ; where j represents month and the horizontal line represents mean value.
  4. 4. The method for identifying short-period drought and flood according to claim 1, wherein in step 4) the method specifically comprises the steps of adopting a month scale Divided by the number of days of the month Obtaining the precipitation suitable for the daily scale climate ; ; By daily precipitation Calculating a difference value to obtain a water quantity balance value reflecting the drought condition of a specific day, namely, the early water surplus and shortage WSD; ; where pr represents the daily precipitation amount, and i represents the number of days accumulated in the early stage.
  5. 5. The method for identifying short period drought and flood according to claim 1, wherein in step 5), the cumulative probability P of the early water surplus and shortage WSD is calculated: ; where α and β represent the scale and shape parameters of the Log-logistic distribution and γ represents the position parameters of the Log-logistic distribution.
  6. 6. The method for identifying short-period drought and flood according to claim 1, wherein in the step 6), the method specifically comprises the steps of performing Gaussian inverse transformation on P to obtain a daily-scale standardized moisture abnormality index SZI: 。
  7. 7. the method for identifying short-period drought and flood according to claim 1, wherein the step 7) specifically comprises: determining drought, flood and drought and flood emergency recognition and conversion thresholds according to a daily scale standardized moisture abnormality index SZI; Specifically, more than 3 consecutive days SZI < -1 are defined as a drought event, SZI > 1 which is more than 3 consecutive days is defined as a flood event, then, the time interval between the end date of the drought event and the start date of the flood event is judged, if the time interval between the end date of the drought event and the start date of the flood event is less than or equal to 30 days, the drought-to-flood event is judged, conversely, the drought-to-flood event is judged, and a specific judging formula of SZI is as follows: ; ; ; wherein SZI denotes a daily scale normalized moisture abnormality index, d denotes a duration of days, And Respectively representing a flood event start date and a drought event end date; Defining the times of occurrence of drought and waterlogging in unit time as the occurrence frequency of the drought and waterlogging; ; Wherein N represents the times of detected drought-to-waterlogging or waterlogging-to-drought events, and Y represents the time span; drought and waterlogging are a compound event, and are divided into two parts during time periods: ; wherein D total represents a drought duration, D drought represents a drought duration, and D flood represents a flood duration; Defining the time from the end of drought/flood to the beginning of flood/drought in a drought/flood emergency as the drought/flood emergency time; ; wherein D tran represents drought and flood turning time, And Respectively representing a flood event start date and a drought event end date; defining the difference between the minimum value of the drought occurrence period SZI and the maximum value of the SZI in the flood period as the occurrence intensity of the drought and the flood; ; Wherein, the Represents the maximum value reached by the daily scale standardized moisture abnormality index SZI during the flood event phase, Represents the minimum reached by the daily scale normalized moisture anomaly index SZI at the drought event stage.
  8. 8. The method for identifying short-period drought and flood according to claim 1, wherein the step 8) specifically comprises determining the variation trend of occurrence frequency, turning time and intensity of the drought and flood by Kendell analysis, and calculating a Kendell Z value according to the following formula: ; where S is a kendel statistic and Var is a standard deviation.

Description

Short-period drought and flood emergency identification method based on standardized moisture abnormality index Technical Field The invention relates to the fields of drought and waterlogging disaster prevention, disaster reduction and drought and waterlogging event identification, in particular to a short-period drought and waterlogging emergency identification method based on a standardized moisture abnormality index. Background Currently, global warming is accelerating the water circulation process, resulting in significant increases in the weather hydrodynamics rate. Extreme events such as drought, storm flood and the like are not isolated any more, but increasingly show a composite characteristic of short-time alternation and rapid conversion, namely a phenomenon of 'drought, flood and the like'. The rapid turning event shows the trend of increasing frequency and accelerating conversion, and the chain type destructive power caused by the rapid turning event breaks through the traditional water conservancy category, seriously threatens the safety of water and grains, and spreads to the multidimensional fields such as geological disasters, ecological degradation, public health risks and the like. Therefore, the method accurately identifies drought and waterlogging emergency, and has important scientific value and practical significance for coping with complex extreme climate risks and constructing a disaster prevention and reduction system with toughness. At present, the methods for identifying drought and waterlogging emergency mainly comprise 2 types, namely, constructing a specific index, and the other type is a comprehensive analysis method based on hydrometeorological variables. The index method is used for setting the intensity and the conversion threshold value of drought and flood events by constructing drought and flood emergency indexes aiming at different scales, so that quantitative identification of the events is realized. Early identification methods are mostly based on long period indexes, such as long period drought and flood emergency indexes, of seasonal scale or month scale, and consider that the turning time between drought and flood is approximately 1 to 2 months. Although the calculation is simple and convenient, the statistical method of the snapshot type is limited by the resolution of the month scale, and the rapid sharp turning process in the ten days or the weather scale cannot be effectively identified, so that the resolution of the short-time extreme events is insufficient. The comprehensive analysis method mainly utilizes time sequence analysis and a run-length theoretical tool, combines variables such as precipitation, runoff and the like, diagnoses the continuity of drought and flood in time, so as to identify the rapid turning process of drought and flood, but is mostly based on month-scale precipitation or runoff index, and is difficult to capture the rapid turning process caused by short-time strong precipitation and the like, and the problems of insufficient timeliness and the like still exist. Disclosure of Invention Aiming at the defects existing in the prior art, the invention provides a short-period drought and flood emergency identification method based on a standardized moisture abnormality index, which accurately identifies drought and flood emergency events through a plurality of methods such as rolling sliding window probability distribution fitting, run theory, mann-Kendall trend inspection, dynamic threshold segmentation, statistical feature analysis and the like, and provides an effective tool for disaster prevention and reduction. The invention aims to realize a short-period drought and waterlogging emergency identification method based on a standardized moisture abnormality index, which comprises the following steps of: 1) Collecting weather data of a research area over the years; 2) Calculating potential evaporative PET; 3) Calculating the appropriate precipitation of the climate of the month scale ; 4) Calculating a water quantity balance value reflecting the drought condition of a specific day, namely, the early water surplus and shortage WSD; 5) Calculating the accumulated probability P of the early water surplus and deficient; 6) Performing Gaussian inverse transformation on the accumulated probability P to obtain a daily-scale standardized moisture abnormality index SZI; 7) Determining drought, flood and drought and flood emergency identification and conversion thresholds according to a daily scale standardized moisture abnormality index SZI, and identifying drought, flood and drought and flood emergency events through a run-length theory; 8) And determining the change trend of the occurrence frequency, turning time and intensity of the drought and waterlogging sharp turn by utilizing Kendell analysis. Further, the step 2) specifically comprises calculating potential vaporized PET according to Penman-Montetith formula: Wherein R n represents surface