阅读说明：本技术 一种产流模式自适应的流域水文预报方法及系统 (Basin hydrological forecasting method and system with self-adaptive runoff yield mode ) 是由 陈璐 罗东 江平 张寒松 易彬 于 2021-06-04 设计创作，主要内容包括：本发明公开了一种产流模式自适应的流域水文预报方法及系统,属于水文学中的水文预报领域。本发明针对流域不同前期土壤含水量特征及降水过程特征,构造了基于蓄满产流、超渗产流和混合产流于一体的流域产流模式判别方法；进一步地,依据无因次单位线原理,根据流域历史洪水过程,推导出了基于小流域地形、地貌特征的无因次综合汇流单位线；并以洪峰目标、峰现时间目标、确定性目标作为评价指标,对各子流域确定的最优产流模式涉及的参数进行优化率定,进而形成完整预报体系。本发明能够针对流域不同土壤含水量特征和降雨特征,确定流域最优下渗模式,并根据流域地形地貌特征,确定流域汇流单位线,具有计算简单、适用范围广、拟合精度高的优点。(The invention discloses a watershed hydrological forecasting method and system with a runoff yield mode self-adaption, and belongs to the field of hydrological forecasting in hydrology. Aiming at different early-stage soil water content characteristics and precipitation process characteristics of a basin, the basin runoff yield mode discrimination method based on integration of full runoff accumulation, super-seepage runoff and mixed runoff yield is constructed; furthermore, according to the non-dimensional unit line principle and the historical flood process of the drainage basin, a non-dimensional comprehensive confluence unit line based on the terrain and landform characteristics of the small drainage basin is deduced; and taking the flood peak target, the peak time target and the certainty target as evaluation indexes, and carrying out optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin so as to form a complete forecasting system. The method can determine the optimal infiltration mode of the drainage basin according to different soil water content characteristics and rainfall characteristics of the drainage basin, and determine the drainage basin confluence unit line according to the topographic features of the drainage basin, and has the advantages of simple calculation, wide application range and high fitting precision.)

1. A watershed hydrological forecasting method with a self-adaptive runoff yield mode is characterized by comprising the following steps:

(1) acquiring relevant data of flood forecasting of a target drainage basin, and dividing the target drainage basin into a plurality of sub-drainage basins;

(2) determining an optimal runoff generating mode of each sub-basin and fitting a corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

(3) substituting the runoff producing process into the corresponding confluence unit line, and simulating an initial flood process of the target watershed;

(4) taking a flood peak target, a peak time target and a certainty target as evaluation indexes, and carrying out optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

2. The method of claim 1, wherein in step (1),

the relevant data of the target watershed flood forecast comprises the following data: hourly rainfall data of the rainfall station, evaporation data, longitude and latitude data of each station, rainfall data of previous M days, and continuous hourly runoff data of the flow station at corresponding time points;

the dividing the target basin into a plurality of sub-basins comprises: and dividing the target drainage basin into a plurality of sub drainage basins by utilizing a Thiessen polygon method.

3. The method according to claim 1 or 2, characterized in that said step (2) comprises in particular the sub-steps of:

(2-1) calculating the early soil water content of each sub-basin:

in the formula, W_i,jThe soil water content of the initial stage of flood generation of the field corresponding to the jth sub-basin on the jth day is set; p_jThe daily rainfall is j days; p_a,j-1The rainfall is influenced for the day-ahead of j-1; n is the early rainfall days influencing the current runoff; k is a soil regression coefficient; when P is present_a,j＞W_mWhen is, P_a,j＝W_mWherein W is_mThe average maximum water storage capacity of the basin is obtained;

(2-2) calculating the continuous maximum rainfall capacity of each sub-basin in x hours and y hours:

in the formula, HP_i,xThe maximum rainfall is x hours continuously for the ith sub-watershed; HP_i,yThe maximum rainfall is y hours continuously for the ith sub-basin; p_i,kThe rainfall of the ith sub-watershed in the kth hour; n is the starting time of continuous maximum rainfall;

(2-3) presetting the early soil water content threshold alpha of each sub-basin₁X hours continuous maximum rainfall threshold alpha₂And y hour continuous maximum rainfall threshold alpha₃And determining the optimal runoff yield mode of each sub-watershed:

a. when W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＞α₃Or W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＜α₃In time, the mixed production flow occurs in the drainage basin, and the production flow formula is as follows:

f_t＝a-bW_t-cT_t

in the formula, T_tCounting time intervals from rising at the flood time t, defaulting to 1 at an initial value, and adding 1 to each subsequent time interval until rising is interrupted; a, b and c are constant coefficients, and each target basin corresponds to different parameters;

b. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＜α₃When the flow field is over-seepage, the flow formula is as follows:

in the formula (f)_tThe drainage basin infiltration capacity at the moment t; w_tThe water content of the soil in the basin at the moment t; c is the stable infiltration rate, D is the soil absorption rate, and all the parameters are normal parameters;

c. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＞α₃When the flow field is over-seepage, the flow formula is as follows:

f_t＝m(WM-W_t)ⁿ+f_c

in the formula, WM is field water capacity; m and n are normal parameters and are related to the property of the soil in the drainage basin; f. of_cStabilizing the infiltration capacity for the drainage basin;

d. when W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＞α₃When the river basin is full of produced water, the produced water formula is as follows:

wherein R is runoff; PE is rainfall for removing evaporation; w₀Initial soil water content, WM field water capacity; w'_mmMaximum soil moisture content; a and B are water storage capacity curve coefficients;

e. when W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＞α₃The runoff area generates super-seepage runoff, and the runoff equation is as follows:

in the formula, KF is a permeability coefficient.

4. The method of claim 3, wherein in step (3), the bus unit line of each sub-basin is determined by:

(3-1) determining the dimensionless integrated unit line of each sub-basin according to the topographic features of the basin:

in the formula, L_iIs the river length of the ith sub-basin, J_iIs the slope of the ith sub-basin, theta_iIs the ith sub-watershed characteristic parameter value, m_iIs the ith sub-basin time lag parameter; through theta_iAnd m_iDetermining the dimensionless integrated unit line u corresponding to each sub-basin by looking up the table_i～x_i；

(3-2) determining the rising duration of each sub-basin by counting the historical flood process of the basin:

in the formula, v_iIs the ith sub-basin time lag;a rise duration for the ith sub-basin; k_iIs the ith sub-watershed unit line parameter; delta t is the watershed unit line calculation time interval;

(3-3) establishing a conversion relation between the dimensionless integrated unit line and the time interval unit line, and determining the confluence unit line of each sub-basin:

in the formula, F_iIs the ith sub-basin area; q. q.s_i～t_iIs a bus unit line of the ith sub-basin.

5. The method according to claim 1 or 4, wherein the step (3) comprises in particular:

substituting the runoff producing process into the corresponding confluence unit line to obtain the runoff process of each sub-basin; and carrying out dislocation accumulation on the flow process corresponding to the runoff process of each sub-basin to obtain the initial flood process of the target basin.

6. The method of claim 1, wherein in step (4),

the flood peak target Obj₁Expressed as:

the peak temporal target Obj₂Expressed as:

the deterministic target Obj₃Expressed as:

in the formula, Q_obs,iIs the measured value of the flow; q_sim,iThe flow prediction value is used; t is_obs,iIs a peak reality measured value; t is_sim,,iThe peak current predicted value is obtained;the measured flow mean value is obtained; q'_obs,iThe flood peak value of the actual measurement field is obtained; q'_sim,iPredicting the flood value of the field; and N is the number of flood times.

7. The method according to claim 1 or 6, wherein in the step (4), the optimizing and calibrating the parameters related to the optimal parturition pattern determined by each sub-basin comprises:

and taking the flood peak target, the peak time target and the certainty target as evaluation indexes, and performing optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin by adopting an SCEUA (sequence-enhanced optimization) algorithm.

8. A runoff yield pattern adaptive watershed hydrologic forecasting system is characterized by comprising:

the acquisition and division module is used for acquiring relevant data of flood forecasting of the target drainage basin and dividing the target drainage basin into a plurality of sub-drainage basins;

the runoff generating mode judging module is used for determining the optimal runoff generating mode of each sub-basin and fitting the corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

the initial flood process simulation module is used for substituting the runoff producing process into the corresponding confluence unit line and simulating the initial flood process of the target watershed;

the final flood process simulation module is used for performing optimization and calibration on parameters related to the optimal runoff generating mode determined by each sub-basin by taking a flood peak target, a peak time target and a certainty target as evaluation indexes; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

Technical Field

The invention belongs to the field of hydrologic prediction in hydrology, and particularly relates to a watershed hydrologic prediction method and a watershed hydrologic prediction system with a self-adaptive runoff yield mode.

Background

The hydrologic forecasting work in China is greatly developed in the past decades, abundant experience is accumulated, a large number of flood forecasting methods have remarkable effect, but because China is wide in territory and complex and diverse in landform types, the forecasting is still not accurate enough in many medium and small watersheds. The reason is mainly that the conditions of the underlying surface of the medium-small watershed are complex, rainfall changes a lot, and the runoff producing mechanism is complex and various, the infiltration process cannot be analyzed by the traditional single runoff producing theory, the runoff producing simulation is the first step of the runoff simulation of the watershed, and if the runoff producing simulation effect is not good, the satisfactory precision cannot be achieved in the whole runoff process basically.

Therefore, the existing hydrologic prediction technology has the technical problems that the runoff generating method is single and the drainage basin infiltration mechanism cannot be analyzed, and further, the runoff prediction of medium and small drainage basins cannot be accurately predicted.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a watershed hydrological forecasting method and a watershed hydrological forecasting system with a self-adaptive runoff producing mode, and aims to solve the technical problems that the runoff producing method is single and the runoff mechanism of a watershed cannot be analyzed in the hydrological forecasting technology, and further, the runoff forecasting of medium and small watersheds cannot be accurately forecasted.

To achieve the above object, according to one aspect of the present invention, there is provided a method for producing river basin hydrologic prediction with adaptive runoff yield pattern, comprising the steps of:

(1) acquiring relevant data of flood forecasting of a target drainage basin, and dividing the target drainage basin into a plurality of sub-drainage basins;

(2) determining an optimal runoff generating mode of each sub-basin and fitting a corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

(3) substituting the runoff producing process into the corresponding confluence unit line, and simulating an initial flood process of the target watershed;

(4) taking a flood peak target, a peak time target and a certainty target as evaluation indexes, and carrying out optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

Further, in the step (1),

the relevant data of the target watershed flood forecast comprises the following data: hourly rainfall data of the rainfall station, evaporation data, longitude and latitude data of each station, rainfall data of previous M days, and continuous hourly runoff data of the flow station at corresponding time points;

the dividing the target basin into a plurality of sub-basins comprises: and dividing the target drainage basin into a plurality of sub drainage basins by utilizing a Thiessen polygon method.

Further, the step (2) specifically includes the following sub-steps:

(2-1) calculating the early soil water content of each sub-basin:

in the formula, W_i,jThe soil water content of the initial stage of flood generation of the field corresponding to the jth sub-basin on the jth day is set; p_jThe daily rainfall is j days; p_a,j-1The rainfall is influenced for the day-ahead of j-1; n is the early rainfall days influencing the current runoff; k is a soil regression coefficient; when P is present_a,j＞W_mWhen is, P_a,j＝W_mWherein W is_mThe average maximum water storage capacity of the basin is obtained;

(2-2) calculating the continuous maximum rainfall capacity of each sub-basin in x hours and y hours:

in the formula, HP_i,xThe maximum rainfall is x hours continuously for the ith sub-watershed; HP_i,yThe maximum rainfall is y hours continuously for the ith sub-basin; p_i,kThe rainfall of the ith sub-watershed in the kth hour; n is the starting time of continuous maximum rainfall;

(2-3) presetting the early soil water content threshold alpha of each sub-basin₁X hours continuous maximum rainfall threshold alpha₂And y hour continuous maximum rainfall threshold alpha₃And determining the optimal runoff yield mode of each sub-watershed:

a. when W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＞α₃Or W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＜α₃In time, the mixed production flow occurs in the drainage basin, and the production flow formula is as follows:

f_t＝a-bW_t-cT_t

in the formula, T_tCounting time intervals from rising at the flood time t, defaulting to 1 at an initial value, and adding 1 to each subsequent time interval until rising is interrupted; a, b and c are constant coefficients, and each target basin corresponds to different parameters;

b. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＜α₃When the flow field is over-seepage, the flow formula is as follows:

in the formula (f)_tThe drainage basin infiltration capacity at the moment t; w_tThe water content of the soil in the basin at the moment t; c is the stable infiltration rate, D is the soil absorption rate, and all the parameters are normal parameters;

c. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＞α₃When the flow field is over-seepage, the flow formula is as follows:

f_t＝m(WM-W_t)ⁿ+f_c

in the formula, WM is field water capacity; m and n are normal parameters and are related to the property of the soil in the drainage basin; f. of_cStabilizing the infiltration capacity for the drainage basin;

d. when W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＞α₃When the river basin is full of produced water, the produced water formula is as follows:

wherein R is runoff; PE is rainfall for removing evaporation; w₀Initial soil water content, WM field water capacity; w'_mmMaximum soil moisture content; a and B are water storage capacity curve coefficients;

e. when W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＞α₃The runoff area generates super-seepage runoff, and the runoff equation is as follows:

in the formula, KF is a permeability coefficient.

Further, in the step (3), the confluence unit line of each sub-basin is determined by:

(3-1) determining the dimensionless integrated unit line of each sub-basin according to the topographic features of the basin:

in the formula, L_iIs the river length of the ith sub-basin, J_iIs the slope of the ith sub-basin, theta_iIs the ith sub-watershed characteristic parameter value, m_iIs the ith sub-basin time lag parameter; through theta_iAnd m_iDetermining the dimensionless integrated unit line u corresponding to each sub-basin by looking up the table_i～x_i；

(3-2) determining the rising duration of each sub-basin by counting the historical flood process of the basin:

in the formula, v_iIs the ith sub-basin time lag;a rise duration for the ith sub-basin; k_iIs the ith sub-watershed unit line parameter; delta t is the watershed unit line calculation time interval;

(3-3) establishing a conversion relation between the dimensionless integrated unit line and the time interval unit line, and determining the confluence unit line of each sub-basin:

in the formula, F_iIs the ith sub-basin area; q. q.s_i～t_iIs a bus unit line of the ith sub-basin.

Further, the step (3) specifically includes:

substituting the runoff producing process into the corresponding confluence unit line to obtain the runoff process of each sub-basin; and carrying out dislocation accumulation on the flow process corresponding to the runoff process of each sub-basin to obtain the initial flood process of the target basin.

Further, in the step (4),

the flood peak target Obj₁Expressed as:

the peak temporal target Obj₂Expressed as:

the deterministic target Obj₃Expressed as:

in the formula, Q_obs,iIs the measured value of the flow; q_sim,iThe flow prediction value is used; t is_obs,iIs a peak reality measured value; t is_sim,,iThe peak current predicted value is obtained;the measured flow mean value is obtained; q'_obs,iThe flood peak value of the actual measurement field is obtained; q'_sim,iPredicting the flood value of the field; and N is the number of flood times.

Further, in the step (4), performing optimization rating on the parameters related to the optimal parturition pattern determined by each sub-watershed includes:

and taking the flood peak target, the peak time target and the certainty target as evaluation indexes, and performing optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin by adopting an SCEUA (sequence-enhanced optimization) algorithm.

In another aspect, the present invention provides a watershed hydrologic forecast system with a self-adaptive runoff yield model, including:

the acquisition and division module is used for acquiring relevant data of flood forecasting of the target drainage basin and dividing the target drainage basin into a plurality of sub-drainage basins;

the runoff generating mode judging module is used for determining the optimal runoff generating mode of each sub-basin and fitting the corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

the initial flood process simulation module is used for substituting the runoff producing process into the corresponding confluence unit line and simulating the initial flood process of the target watershed;

the final flood process simulation module is used for performing optimization and calibration on parameters related to the optimal runoff generating mode determined by each sub-basin by taking a flood peak target, a peak time target and a certainty target as evaluation indexes; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:

(1) according to different early-stage soil water content characteristics and rainfall process characteristics of the drainage basin, the drainage basin runoff yield mode distinguishing method based on the integration of the full runoff yield, the super-seepage runoff yield and the mixed runoff yield is constructed, and the runoff yield process of the small and medium drainage basins is analyzed. Therefore, the runoff forecasting precision of the medium and small watershed is improved.

(2) The invention determines a basin dimensionless unit line equation according to the topographic and geomorphic characteristics of each sub-basin, determines the rise duration of each sub-basin by counting the historical flood process of the basin, further establishes the conversion relation between the dimensionless unit line and the time interval unit line and determines the confluence unit line of each sub-basin. And the medium and small watershed converging process is analyzed, so that the medium and small watershed runoff forecasting precision is improved.

Drawings

Fig. 1 is a flowchart of a watershed hydrologic prediction method with adaptive runoff yield mode according to an embodiment of the present invention;

FIG. 2 is a plot of site distribution and river distribution for a region of interest according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating a selected flood process and its rainfall process according to an embodiment of the present invention;

FIGS. 4(a) and 4(b) are diagrams of basin net rain processes calculated by respective infiltration models;

FIG. 5 is a bus unit line process diagram;

figure 6 is a comparison of simulated flood versus measured flood for each infiltration model.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, a flow chart of a watershed hydrological forecasting method with a self-adaptive runoff yield mode provided by an embodiment of the present invention includes the following steps:

(1) acquiring relevant data of flood forecasting of a target drainage basin, and dividing the target drainage basin into a plurality of sub-drainage basins;

specifically, the data related to the target basin flood forecast includes: hourly rainfall data of the rainfall station, evaporation data, longitude and latitude data of each station, rainfall data of previous M days, and continuous hourly runoff data of the flow station at corresponding time points;

the dividing the target basin into a plurality of sub-basins comprises: and dividing the target drainage basin into a plurality of sub drainage basins by utilizing a Thiessen polygon method.

(2) Determining an optimal runoff generating mode of each sub-basin and fitting a corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

specifically, the step (2) specifically includes the following substeps:

(2-1) calculating the early soil water content of each sub-basin:

in the formula, W_i,jThe soil water content of the initial stage of flood generation of the field corresponding to the jth sub-basin on the jth day is set; p_jThe daily rainfall is j days; p_a,j-1The rainfall is influenced for the day-ahead of j-1; n is the early rainfall days influencing the current runoff; k is a soil regression coefficient; when P is present_a,j＞W_mWhen is, P_a,j＝W_mWherein W is_mThe average maximum water storage capacity of the basin is obtained;

(2-2) calculating the continuous maximum rainfall capacity of each sub-basin in x hours and y hours:

in the formula, HP_i,xThe maximum rainfall is x hours continuously for the ith sub-watershed; HP_i,yThe maximum rainfall is y hours continuously for the ith sub-basin; p_i,kThe rainfall of the ith sub-watershed in the kth hour; n is the starting time of continuous maximum rainfall;

(2-3) presetting a soil water content threshold alpha at the early stage of each sub-basin according to the historical flood process and the underlying surface characteristics of the basin₁X hours continuous maximum rainfall threshold alpha₂And y hour continuous maximum rainfall threshold alpha₃And determining the optimal runoff yield mode of each sub-watershed:

a. when W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＜α₁、HP_i,6＜α₂And HP_i,12＞α₃Or W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＜α₃In time, the mixed production flow occurs in the drainage basin, and the production flow formula is as follows:

f_t＝a-bW_t-cT_t

in the formula, T_tCounting time intervals from rising at the flood time t, defaulting to 1 at an initial value, and adding 1 to each subsequent time interval until rising is interrupted; a, b and c are constant coefficients, and each target basin corresponds to different parameters;

b. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＜α₃When the flow field is over-seepage, the flow formula is as follows:

in the formula (f)_tThe drainage basin infiltration capacity at the moment t; w_tThe water content of the soil in the basin at the moment t; c is the stable infiltration rate, D is the soil absorption rate, and all the parameters are normal parameters;

c. when W is_i,j＜α₁、HP_i,6＞α₂And HP_i,12＞α₃When the flow field is over-seepage, the flow formula is as follows:

f_t＝m(WM-W_t)ⁿ+f_c

in the formula, WM is field water capacity; m and n are normal parameters and are related to the property of the soil in the drainage basin; f. of_cStabilizing the infiltration capacity for the drainage basin;

d. when W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＜α₃Or W is_i,j＞α₁、HP_i,6＜α₂And HP_i,12＞α₃When the river basin is full of produced water, the produced water formula is as follows:

wherein R is runoff; PE is rainfall for removing evaporation; w₀Initial soil water content, WM field water capacity; w_m'_mMaximum soil moisture content; a and B are water storage capacity curve coefficients;

e. when W is_i,j＞α₁、HP_i,6＞α₂And HP_i,12＞α₃The runoff area generates super-seepage runoff, and the runoff equation is as follows:

in the formula, KF is a permeability coefficient.

(3) Substituting the runoff producing process into the corresponding confluence unit line, and simulating an initial flood process of the target watershed;

specifically, the bus unit line of each sub-basin is determined by:

(3-1) determining the dimensionless integrated unit line of each sub-basin according to the topographic features of the basin:

in the formula, L_iIs the river length of the ith sub-basin, J_iIs the slope of the ith sub-basin, theta_iIs the ith sub-watershed characteristic parameter value, m_iIs the ith sub-basin time lag parameter; through theta_iAnd m_iDetermining the dimensionless integrated unit line u corresponding to each sub-basin by looking up the table_i～x_i；

(3-2) determining the rising duration of each sub-basin by counting the historical flood process of the basin:

in the formula (I), the compound is shown in the specification,v_iis the ith sub-basin time lag;a rise duration for the ith sub-basin; k_iIs the ith sub-watershed unit line parameter; delta t is the watershed unit line calculation time interval;

(3-3) establishing a conversion relation between the dimensionless integrated unit line and the time interval unit line, and determining the confluence unit line of each sub-basin:

in the formula, F_iIs the ith sub-basin area; q. q.s_i～t_iIs a bus unit line of the ith sub-basin.

Further, after the confluence unit line of each sub-basin is determined, substituting the flow production process into the corresponding confluence unit line to obtain the runoff process of each sub-basin; and carrying out dislocation accumulation on the flow process corresponding to the runoff process of each sub-basin to obtain the initial flood process of the target basin.

(4) Taking a flood peak target, a peak time target and a certainty target as evaluation indexes, and carrying out optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

Specifically, the rainfall, evaporation and runoff data of each sub-basin in the step (1) are input into the steps (2) and (3), a flood peak target, a peak time target and a certainty target are respectively used as evaluation indexes, and an SCEUA algorithm is adopted to carry out optimization and calibration on each runoff production model parameter, wherein an objective function formula is as follows:

flood peak target Obj₁Expressed as:

peak time target Obj₂Expressed as:

deterministic target Obj₃Expressed as:

in the formula, Q_obs,iIs the measured value of the flow; q_sim,iThe flow prediction value is used; t is_obs,iIs a peak reality measured value; t is_sim,,iThe peak current predicted value is obtained;the measured flow mean value is obtained; q'_obs,iThe flood peak value of the actual measurement field is obtained; q'_sim,iPredicting the flood value of the field; and N is the number of flood times.

Carrying out weight distribution on the flood peak target, the peak time target and the deterministic target function to obtain a comprehensive target:

Obj＝mObj₁+nObj₂+pObj₃

wherein m, n and p are weight coefficients, and m + n + p is 1; preferably, Obj ═ 0.4Obj₁+0.4Obj₂+0.2Obj₃。

The specific calculation steps of the SCEUA algorithm are as follows:

(4-1) initializing, wherein the number of parameters to be optimized is assumed to be n, a population number s and a partition number p;

(4-2) randomly generating a set of samples within a feasible space: x₁,X₂,…,X_sAnd calculating a corresponding objective function value F_i(i＝1,2,…,s)；

(4-3) mixing the sample (X)₁,X₂,…,X_s) Arranged in ascending order according to the corresponding objective function values and stored in array D (X)_i,F_i)(i＝1,2,…,s)；

(4-4) sequentially placing D into p partitions, and storing D into the kth partitionThe sample points are: a. the^k:{X_p(i-1)+k(i ═ 1,2, …, m), in which

(4-5) independently calculating each partition by applying a CCE algorithm;

(4-6) sequentially arranging the samples subjected to evolution calculation in ascending order of objective function values and storing the samples into an array D, and sequentially placing the sample points into p partitions by the method in (4-4);

and (4-7) checking whether the sample point meets the convergence condition, if so, finishing the calculation, and otherwise, continuously repeating the steps (4-4) to (4-7).

In another aspect, the present invention further provides a watershed hydrologic forecast system with a flow generation mode self-adaptation, including:

the acquisition and division module is used for acquiring relevant data of flood forecasting of the target drainage basin and dividing the target drainage basin into a plurality of sub-drainage basins;

the runoff generating mode judging module is used for determining the optimal runoff generating mode of each sub-basin and fitting the corresponding runoff generating process based on the magnitude relation between the early-stage soil water content factor and the rainfall process factor of each sub-basin and the corresponding threshold;

the initial flood process simulation module is used for substituting the runoff producing process into the corresponding confluence unit line and simulating the initial flood process of the target watershed;

the final flood process simulation module is used for performing optimization and calibration on parameters related to the optimal runoff generating mode determined by each sub-basin by taking a flood peak target, a peak time target and a certainty target as evaluation indexes; and substituting the fitted runoff producing process after the parameters are optimized into the corresponding confluence unit line to obtain the final flood process of the target watershed.

The division of each module in the watershed hydrological forecasting system with the self-adaptive runoff producing mode is only used for illustration, and in other embodiments, the watershed hydrological forecasting system with the self-adaptive runoff producing mode can be divided into different modules as required to complete all or part of the functions of the watershed hydrological forecasting system with the self-adaptive runoff producing mode.

In order to more clearly show the purpose, structure and technical scheme of the invention, the invention is further described in detail by using the meizhou watershed and the attached drawings, and the specific implementation steps comprise:

(1) collecting the flood process extract data of each hydrological site above the mountainous point in the Muzhou drainage basin, and dividing the target drainage basin into a plurality of sub-drainage basins by using a Thiessen polygon method;

specifically, the area of the region above the Sharp mountain station of the Muzhou drainage basin is 1578km²The total number of rainfall stations and a flow rate station is 21, the station distribution and the river distribution of a research area are shown in fig. 2, actual measurement flood of 8 months, 17 days to 8 months, 19 days in 2013 is taken as an example to carry out embodiment research, and the rainfall and flood process in a field is shown in fig. 3.

(2) According to the historical flood process and underlying surface conditions of the Meizhou drainage basin, the soil water content threshold value at the early stage of the drainage basin and the maximum precipitation threshold values of 6h and 12h in succession are respectively set to be 45, 40 and 70; calculating the early soil water content and the continuous maximum precipitation for 6h and 12h, determining the optimal runoff yield mode of each sub-basin and fitting the corresponding runoff yield process;

specifically, the water content of the soil at the early stage of the drainage basin and the maximum precipitation for 6 hours and 12 hours continuously are shown in the following table 1; the watershed net rain process lines calculated by the respective runoff producing models are shown in fig. 4(a) and 4 (b).

(3) Calculating a confluence unit line of each basin by adopting a dimensionless unit line based on the landform and the landform of the sub-basins; substituting the runoff producing process into the corresponding confluence unit line, and simulating an initial flood process of the target watershed;

specifically, the watershed confluence unit line is shown in fig. 5, and the flooding process simulated by each model is shown in fig. 6.

(4) Respectively taking the flood peak relative error, the peak time error and the certainty coefficient as objective functions, and adopting an SCEUA optimization algorithm to carry out optimization rate determination on parameters related to the optimal production flow mode determined by each sub-basin; substituting the fitted runoff producing process after parameter optimization into the corresponding confluence unit line to obtain a final flood process of the target watershed;

specifically, the optimal parameters of each model are shown in table 2 below, and the calculated flood peak relative error, peak temporal error and certainty coefficient are shown in table 3 below.

TABLE 1 watershed runoff producing pattern influencing factor

TABLE 2 optimal parameters for the calibration of each infiltration model

TABLE 3 Objective function calculation for each infiltration model

According to the data in table 1, according to the production flow discriminant extracted by the method, the flood meets the situation g, and a mixed production flow mode should be selected. The results of fig. 6 and table 2 show that the vertical-mixed production flow model has the best effect for the peak relative error index, the peak relative error is 1.93%, the error is the minimum in all models, and other production flow models are as follows: the relative flood peak errors of the Philips, Holland, Green-Amp and the full runoff accumulation models are respectively as follows: -4.82%, 18.23%, 3.27% and-17.63%; for the peak time error index, the vertical-mixture and green-empat runoff generating models have the best effect, the peak time errors are all 0h, and other runoff generating models are as follows: the peak time errors of the Philips, Holstein and the full-production flow model are respectively as follows: -1h, -1h and-5 h, all earlier than the actual flood peak; for the deterministic coefficient index, the vertical-hybrid current generation model works best, with a deterministic coefficient of 0.974, the largest of all models. Other production flow models are: the deterministic coefficients of the philips, holtany, green-amplat and the flooded runoff yield models are respectively: 0.813, 0.678, 0.912, and 0.624. In conclusion, the flood process simulated by the vertical-mixed runoff yield model has the best effect and the minimum index error.

In conclusion, the invention discloses a basin hydrological forecasting method and a basin hydrological forecasting system with a runoff yield mode self-adaption, and the basin runoff yield mode judging method based on the integration of the accumulation of the runoff yield, the super-osmotic runoff yield and the mixed runoff yield is constructed aiming at the characteristics of the water content of the soil in different early stages of the basin and the characteristics of the precipitation process; furthermore, a dimensionless integrated convergence unit line based on the terrain and landform characteristics of a small watershed is deduced according to the dimensionless unit line principle; and taking the flood peak target, the peak time target and the certainty target as evaluation indexes, and carrying out optimization and calibration on parameters related to the optimal runoff yield mode determined by each sub-basin so as to form a complete forecasting system. The method can determine the optimal infiltration mode of the drainage basin according to different soil water content characteristics and rainfall characteristics of the drainage basin, and determine the drainage basin confluence unit line according to the topographic features of the drainage basin, and has the advantages of simple calculation, wide application range and high fitting precision.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.