CN113724802A - Calculation method for influence of decoupling evaporation on salt content of lake and reservoir water body - Google Patents

Calculation method for influence of decoupling evaporation on salt content of lake and reservoir water body Download PDF

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CN113724802A
CN113724802A CN202111039505.5A CN202111039505A CN113724802A CN 113724802 A CN113724802 A CN 113724802A CN 202111039505 A CN202111039505 A CN 202111039505A CN 113724802 A CN113724802 A CN 113724802A
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陈洁
高燕燕
张瑜婷
钱会
杨乔洋
李玮卿
肖珊
刘庆
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Changan University
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Abstract

The invention discloses a method for calculating influence of decoupling evaporation on salt content of a water body in a lake reservoir, which comprises the following steps: firstly, acquiring hydrological meteorological data of a lake and a reservoir and collecting T of the lake and the reservoirkTime to Tk+1Performing water chemistry analysis on a water sample at any moment and a lake and reservoir supply item water sample and a drainage item water sample, establishing a water balance equation and a chloride ion mass conservation equation, and calculating the inflow and outflow of underground water to and from the lake; then calculating TkAnd Tk+1The lake water mineral saturation at the moment; then determining a virtual water sample and decoupling the influence of evaporation; and finally, determining the hydrological geochemical action participating in the reaction, establishing a six-element equation of a first order, solving the hydrological geochemical reaction quantity, and comparing the hydrological geochemical reaction quantity with the lake water mineral saturation. The method of the invention realizes the decoupling of the influence of the evaporation effect and the hydrological geochemistry effect on the water salinity of the lakes and reservoirs, namely respectively quantifies the influence of the evaporation effect and the hydrological geochemistry effect on the water salinity, and provides scientific and technological support for the formulation of lake resource management and regulation schemes.

Description

Calculation method for influence of decoupling evaporation on salt content of lake and reservoir water body
Technical Field
The invention belongs to the technical field of water environment and ecological protection, and particularly relates to a calculation method for influence of decoupling evaporation on salt content of a water body in a lake reservoir.
Background
At present, the global face of severe water crisis is a non-competitive fact, and the water quantity type water shortage problem and the water quality type water shortage problem become important factors for restricting the development of socioeconomic development. About 21% of the global fresh water resources come from lakes and reservoirs, and fresh water lakes account for 45% of the total area of lakes in China, so that the fresh water lakes become important water resources for industrial and agricultural production and life and play an important role in maintaining the regional ecological environment. The water evaporation is a main link in the water circulation process in the nature, and because the water surface evaporation only evaporates water, salt is remained in the lake, and along with the salt accumulation in the water evaporation process, the salt content of the water in the lake and reservoir is increased and even salted, so that the resource value and the ecological value of the water are greatly reduced. The influence of limited precipitation and surface runoff is particularly prominent on lakes and reservoirs in dry regions.
At present, the change characteristics of the salinity of lake and reservoir water are generally researched according to the Total Dissolved Solids (TDS) content of the lake and reservoir water in different periods, and the salinity equilibrium is calculated through water equilibrium based on the mass conservation law. However, the change in salt under the influence of evaporation is not a simple linear process, but is accompanied by a series of hydrogeochemical reactions, such as carbonate precipitation, evaporite dissolution, alternate cation adsorption, etc. The hydrological geochemical process under the action of evaporation is influenced by factors such as climatic conditions, lake water supply sources and the like, and has obvious dynamic change characteristics. However, the contribution of evaporation and hydrological geochemical coupling to salinity increase or decrease is often neglected, increasing uncertainty in simulated reduction and prediction of salinity changes in water bodies in lakes and reservoirs. Therefore, the influence of lake and reservoir evaporation on salinity is decoupled, deep understanding of the process is beneficial to developing lake resource management and regulation and control scheme formulation, and the method has important theoretical value and practical significance.
Disclosure of Invention
The invention aims to provide a calculation method for decoupling the influence of evaporation on lake and reservoir water salinity, and the decoupling of the influence of evaporation and hydrological geochemistry on the lake and reservoir water salinity is realized.
The technical scheme adopted by the invention is that the calculation method for the influence of decoupling evaporation on the salinity of the lake and reservoir water body is implemented according to the following steps:
step 1, acquiring hydrological meteorological data of lakes and reservoirs, and collecting delta T time periods, namely TkTime to Tk+1Constantly water samples and lake and reservoir supply item and drainage item water samples are subjected to water chemical analysis to determine Na+、K+、Ca2+、Mg2+、Cl-、SO4 2-And HCO3 -Concentration;
step 2, establishing a water quantity balance equation and a chloride ion mass conservation equation, and calculating the inflow runoff and the outflow runoff of the underground water;
step 3, calculating TkAnd Tk+1The mineral saturation S of lake water at the moment;
step 4, determining a virtual water sample and decoupling the influence of evaporation;
and step 5, determining the hydrological geochemical action participating in the reaction, establishing a six-element equation of a first order, solving the hydrological geochemical reaction quantity, comparing the hydrological geochemical reaction quantity with the lake water mineral saturation, and decoupling the influence of the hydrological geochemical action.
The present invention is also characterized in that,
in the step 1, the lake and reservoir replenishment items are atmospheric precipitation P, surface runoff replenishment SI and artificial replenishment HI; the lake and reservoir excretion items are evaporation capacity E, surface runoff excretion SO and human development and utilization HO.
In the step 2, the method specifically comprises the following steps: equations (1) and (2) are obtained according to the law of mass conservation:
Figure BDA0003248573740000031
Figure BDA0003248573740000032
in the formula, GI is the inflow runoff of the underground water to the lake, GO is the outflow runoff of the underground water to the lake, and delta V is the volume change of the water body in the delta t period of the lake reservoir; clPReduction of chloride ion concentration, Cl, for atmospheric purposesSIReplenishing surface runoff with water chlorine ion concentration, ClGIReplenishing water with chloride ion concentration, Cl, for subsurface runoffHIFor artificially replenishing the water body with the concentration of chloride ions,
Figure BDA0003248573740000033
is the average value of the concentration of chloride ions in the water body of the lake and reservoir in the delta t period, VTkAnd VTk+1Are respectively lake reservoir TkAnd Tk+1Water volume at time, ClTkAnd ClTk+1Are respectively lake reservoir TkAnd Tk+1The concentration of the chlorine ions in the water body at any moment.
And (3) combining the vertical type (1) and the formula (2), and solving to obtain the runoff (GI) of the groundwater in the lake and the runoff (GO) of the groundwater out of the lake at the time.
In step 4, the method specifically comprises the following steps:
calculating the end time T according to the law of conservation of massk+1The component value m of the ith (i ═ 1, 2.., 6) corresponding to the water sampleiIncluding Na+、K+、Ca2+、Mg2+、SO4 2-And HCO3 -As shown in formula (3);
Figure BDA0003248573740000034
in the formula, Ai,PConcentration of the ith component in atmospheric precipitation, Ai,SIReplenishment of surface runoff with component concentration i, Ai,GIThe concentration of the ith component of the groundwater runoff into the lake, Ai,HIFor artificial water supplementation of the ith component concentration, ATiIs TiThe concentration of the ith component in the water body in the lake and reservoir at any moment,
Figure BDA0003248573740000035
the concentration mean value of the ith component of the lake and reservoir water body in the delta t period;
from TkTime to Tk+1At any moment, the concentration distribution of each component of the water body in the lake and reservoir is changed to Ai；
Let i component Tk+1The actual observed concentration of the lake water at the moment is Ri,T1；
When A isi>Ri,T1The time indicates that the content of the ith ion is reduced in the water sample at the end moment by hydrologic geochemistry;
when A isi＝Ri,T1The time is that the content of the ith ion is not changed in the water sample at the end moment by hydrologic geochemistry;
when A isi<Ri,T1The time indicates that the content of the ith ion is increased in the water sample at the end moment by the hydrologic geochemistry;
at this time, the water sample composed of each ion under the influence of the evaporation is defined as a virtual water sample.
In step 5, the method specifically comprises the following steps:
virtual water sample and Tk+1The mass increase and decrease of the ith ion in the water sample at the moment is the mass increase and decrease of the ion under the action of hydrology and geochemistry, and is recorded as bi(ii) a Simulating to solve the problem that lake water goes from 'virtual water sample' to Tk+1The relevant hydrological geochemistry effect in the process of the lake water sample at the moment is shown as a formula (4);
virtual water sample + reactant ═ Tk+1A lake water sample + a product (4) at the moment;
in the initial body of water, x is dissolved per liter of water1X of a first mineral of (1)2…, xmThe end-point water quality is formed after the n-th mineral, and the increment of the element in the i-th water quality in the end-point water quality is b compared with the initial mixed water qualityiAs shown in formula (5);
Figure BDA0003248573740000041
in the formula (I), the compound is shown in the specification,aijis the stoichiometric number of the element in the ith relative to the mineral in the jth and is equal in value to the number of moles of the ith element resulting from complete dissolution of 1mol of the jth mineral;
selecting j mineral elements, establishing a j-element linear equation, and solving xj，xjPositive values indicate dissolution and negative values indicate precipitation; x is to bejComparing the sign of the mineral solubility S with the sign of the mineral solubility S, if the signs are consistent, indicating that the calculation result is correct, and if the signs are not consistent, indicating that the reactant and the product selected in the formula (4) need to be adjusted, and repeating the step 5 until the calculation result is correct.
The method has the advantages of realizing the decoupling of the influence of the evaporation effect and the hydrological geochemistry effect on the water salinity of the lakes and reservoirs, namely respectively quantifying the influence of the evaporation effect and the hydrological geochemistry effect on the water salinity, and providing scientific and technological support for the formulation of lake resource management and regulation schemes.
Drawings
FIG. 1 is a flow chart of an evaluation method for decoupling influence of lake and reservoir evaporation on salinity according to the invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention discloses a calculation method for influence of decoupling evaporation on salt content of a water body in a lake reservoir, which is implemented according to the following steps as shown in figure 1:
step 1, acquiring hydrological meteorological data of a lake and a reservoir, developing investigation to determine water circulation characteristics of the lake and the reservoir, and collecting water in the lake and the reservoir within a delta T period (T)kTime to Tk+1Time) water sample, lake and reservoir supply item water sample and drainage item water sample, performing water chemistry analysis, and determining sodium ions (Na)+) Potassium ion (K)+) Calcium ion (Ca)2+) Magnesium ion (Mg)2+) Chloride ion (Cl)-) Sulfate radical (SO)4 2-) And bicarbonate radical (HCO)3 -) Concentration;
the lake and reservoir replenishment items comprise atmospheric precipitation P, surface runoff replenishment SI and artificial replenishment HI; the lake and reservoir excretion items are evaporation capacity E, surface runoff excretion SO and human development and utilization HO;
step 2, establishing a water quantity balance equation and a chloride ion mass conservation equation, and calculating the inflow runoff and the outflow runoff of the underground water;
the method specifically comprises the following steps: because the exchange between the lake and the underground water is difficult to observe, the water exchange between the lake and the underground water is calculated by adopting chloride ions which do not generate chemical reaction with other ions and have stable properties, and the formula (1) and the formula (2) can be obtained according to the mass conservation law:
Figure BDA0003248573740000061
Figure BDA0003248573740000062
in the formula, P is atmospheric precipitation, SI is surface runoff supply quantity, GI is groundwater runoff quantity, HI is artificial water supply quantity, E is evaporation quantity, SO is surface runoff discharge quantity, GO is groundwater runoff quantity, and HO is human development and utilization quantity. Δ V is the lake Δ T period (T)kTime to Tk+1Time) of the change in volume of the water body.
ClPReduction of chloride ion concentration, Cl, for atmospheric purposesSIReplenishing surface runoff with water chlorine ion concentration, ClGIReplenishing water with chloride ion concentration, Cl, for subsurface runoffHIFor artificially replenishing the water body with the concentration of chloride ions,
Figure BDA0003248573740000063
the chlorine ion concentration of the water body in the lake and reservoir is the mean value of the chlorine ion concentration of the water body in the lake and reservoir in the delta t period, namely the SO discharged by surface runoff, the GO of underground water inflow runoff and the HO water body concentration, V, developed and utilized by human beingsTkAnd VTk+1Are respectively lake reservoir TkAnd Tk+1Water volume at time, ClTkAnd ClTk+1Are respectively lake reservoir TkAnd Tk+1The concentration of the chlorine ions in the water body at any moment.
The joint type (1) and the formula (2) can be solved to obtain the groundwater runoff (GI) and the groundwater runoff (GO) of the current period.
Step 3, calculating TkAnd Tk+1The mineral saturation S of lake water at the moment;
s >0 indicates that the mineral is in a supersaturated state relative to the lake water, S ═ 0 indicates that the mineral is in an equilibrium state relative to the lake water, and when S <0 indicates that the mineral is in an unsaturated state relative to the lake water.
Step 4, determining a virtual water sample, and decoupling the influence of evaporation;
the method specifically comprises the following steps: calculating the end time T according to the law of conservation of massk+1The component value m of the ith (i ═ 1, 2.., 6) corresponding to the water sampleiIncluding sodium ion (Na)+) Potassium ion (K)+) Calcium ion (Ca)2+) Magnesium ion (Mg)2+) Sulfate radical (SO)4 2-) And bicarbonate radical (HCO)3 -) As shown in formula (3);
Figure BDA0003248573740000071
in the formula, Ai,PConcentration of the ith component in atmospheric precipitation, Ai,SIReplenishment of surface runoff with component concentration i, Ai,GIThe concentration of the ith component of the groundwater runoff into the lake, Ai,HIFor artificial water supplementation of the ith component concentration, ATiIs TiThe concentration of the ith component in the water body in the lake and reservoir at any moment,
Figure BDA0003248573740000072
the concentration of the ith component of the lake reservoir water body in the delta t period is the mean value of the concentration of the ith component of the lake reservoir water body, namely the concentration of the ith component of the HO water body in surface runoff drainage SO, underground water inflow runoff GO and human development and utilization.
As with chloride ion, concentration of the ith component occurs under evaporative concentration, i.e., from T if only evaporative action is consideredkTime to Tk+1At any moment, the concentration distribution of each component of the water body in the lake and reservoir is changed to Ai。
Let i component Tk+1The actual observed concentration of the lake water at the moment is Ri,T1(established in step 1):
when A isi>Ri,T1The time indicates that the content of the ith ion is reduced in the water sample at the end moment by hydrologic geochemistry;
when A isi＝Ri,T1The time is that the content of the ith ion is not changed in the water sample at the end moment by hydrologic geochemistry;
when A isi<Ri,T1The time indicates that the content of the ith ion is increased in the water sample at the end moment by the hydrologic geochemistry;
at this time, each ion (A) under the influence of the evaporationi) The composed water samples are defined as virtual water samples.
Step 5, decoupling the hydrological geochemistry;
the method specifically comprises the following steps: virtual water sample and Tk+1The mass increase and decrease of the ith ion in the water sample at the moment is the mass increase and decrease of the ion under the action of hydrology and geochemistry, and is recorded as bi. Simulating to solve the problem that lake water goes from 'virtual water sample' to Tk+1The relevant hydrological geochemistry effect in the process of the lake water sample at the moment is shown as a formula (4);
virtual water sample + reactant ═ Tk+1A lake water sample + a product (4) at the moment;
in the initial body of water, x is dissolved per liter of water1(mmol) of a first mineral (dissolved positive and precipitated negative), x2(mmol) of a second mineral, …, xm(mmol) of the n-th mineral, an end-point water quality is formed, and the increment of the element in the i-th water quality in the end-point water quality is b compared with the initial mixed water qualityi(mmol) as shown in formula (5);
Figure BDA0003248573740000081
in the formula, aijIs the stoichiometric number of the element in the ith relative to the mineral in the jth and is equal in value to the number of moles of the ith element resulting from complete dissolution of 1mol of the jth mineral. Corresponds to 6 components (Na)+、K+、Ca2+、Mg2+、SO4 2-And HCO3 -) The 6 mineral elements are respectively Na and KCa, Mg, S and C.
Selecting j mineral elements, establishing a j-element linear equation, and solving xjI.e. xjAs a result of the salinity change of the water body under the influence of the hydrological geochemistry, xjPositive values indicate dissolution and negative values indicate precipitation.
X is to bejComparing the sign of the mineral solubility S with the sign of the mineral solubility S, if the signs are consistent, indicating that the calculation result is correct, and if the signs are not consistent, indicating that the reactant and the product selected in the formula (4) need to be adjusted, and repeating the step 5 until the calculation result is correct.
The virtual water sample is the result of decoupling of evaporation, namely the result of salinity change of the lake water body affected by evaporation; hydrological geochemistry x of virtual water sample in water sample at certain time in time periodjI.e. the effect of the hydrological geochemistry.
Examples
In the embodiment, the method is applied to lakes in arid and semiarid regions upstream of the yellow river basin to decouple the influence of evaporation on the salinity of the water body of the lakes. Selecting 1 lake for representative calculation. The lake is in arid and semi-arid regions, has the characteristics of strong evaporation and rare rainfall, has extremely small surface runoff replenishment amount, and plays an important role in maintaining the ecological environment of the lake by using underground water. Meanwhile, because the water surface is strongly evaporated, the lake receives artificial water replenishing supply from the yellow river. Relevant research in China is mainly focused on the change rule of the lake water environment at present, and research aiming at the salt change and mechanism of the lake is insufficient.
Step 1: look up the hydrological weather yearbook in the area at T0-T1The precipitation P (310.2mm) and evaporation E (2723.2mm) of the area where the lake is located in the time period.
Obtaining the lake area of 13.96km according to the lake basic data and the remote sensing image2The lake level remained essentially unchanged during the study period. Based on the investigation and analysis of lake water circulation characteristics, the supply items of the lake are respectively determined to have atmospheric precipitation P (310.2mm), groundwater inflow runoff GI and artificial water supply HI (3148 multiplied by 10)4m3) The lake discharge items are evaporation E (2723.2mm) and groundwater runoffGO。
Collecting samples to measure lake water, atmospheric precipitation, surface runoff and groundwater sample in replenishment area, performing indoor hydrochemical characteristic analysis, and determining main ion content (including Na) in each water body+、K+、Ca2+、Mg2+、Cl-、SO4 2-And HCO3 -)。
And 2, establishing a lake water balance equation and a mass conservation equation in the period, and calculating the inflow runoff and the outflow runoff of the underground water.
Wherein, as the lake level is basically unchanged, the water level has a value of delta V-0 (V)0＝V1) The water balance equation of the lake is as follows:
(P+SI+GI+HI)-(E-GO)＝0 (1)
in the formula, P is atmospheric precipitation, GI is groundwater runoff, HI is artificial water supplement, E is evaporation, and GO is groundwater runoff. V0And V1Are respectively T0And T1The water volume of the lake and reservoir at any moment.
The lake chloride ion mass conservation equation is as follows:
Figure BDA0003248573740000101
in the formula, ClPReduction of chloride ion concentration, Cl, for atmospheric purposesSIReplenishing surface runoff with water chlorine ion concentration, ClGIReplenishing water with chloride ion concentration, Cl, for subsurface runoffHIFor artificially replenishing the water body with the concentration of chloride ions,
Figure BDA0003248573740000102
the method is used for researching the mean value of the concentration of the chlorine ions in the water bodies of lakes and reservoirs in the time period, namely the concentration of the chlorine ions in GO water bodies of groundwater runoff into lakes, namely Cl0And Cl1Are respectively T0And T1The concentration variation of the chloride ions in the water body in the lake and reservoir at any moment.
And (3) solving the formulas (1) and (2), and calculating to obtain the underground water inflow runoff GI and the underground water outflow runoff GO.
And 3, determining the mineral saturation.
Calcite (CaCO) in lake water is obtained through calculation3) Dolomite (CaMg (CO)3)2) And gypsum (CaSO)4) Of (b), wherein SCalcite>0 and SDolomite>0, indicating that the lake water is supersaturated with respect to calcite and dolomite, i.e., calcite and dolomite cannot be further dissolved in the lake water, whereas SGypsum plaster<0, indicates that the gypsum is in an unsaturated state and may continue to dissolve in lake water.
Step 4, determining a virtual water sample, and decoupling the influence of evaporation;
calculating T according to GI and GO obtained by calculation and solution by adopting formula (3)1Sodium ion (Na) in all cases+) Potassium ion (K)+) Calcium ion (Ca)2+) Magnesium ion (Mg)2+) Sulfate radical (SO)4 2-) And bicarbonate radical (HCO)3 -) The concentrations, namely:
Figure BDA0003248573740000111
in the formula, AiIs the i (Na)+、K+、Ca2+、Mg2+、SO4 2And HCO3 -) Component value T1Concentration calculated at the moment, Ai,PConcentration of the ith component in atmospheric precipitation, Ai,SIReplenishment of surface runoff with component concentration i, Ai,GIThe concentration of the ith component of the groundwater runoff into the lake, Ai,HIFor artificial water supplementation of the ith component concentration, AT0Is T0The concentration of the ith component in the water body in the lake and reservoir at any moment,
Figure BDA0003248573740000113
is T0To T1And (3) the concentration mean value of the ith component of the lake and reservoir water body in the time period, namely the concentration of the ith component of the GO body in the groundwater runoff.
As with chloride ion, concentration of the ith component occurs under evaporative concentration, i.e., from T if only evaporative action is considered0Time to T1At any moment, the concentration distribution of each component of the water body in the lake and reservoir is changed to Ai. At this time, each ion (m) under the influence of evaporation is converted intoi) The composed water samples are defined as virtual water samples.
Component I ofk+1The actual observed concentration of the lake water at the moment is Ri,T1(step 1 has been determined), and the calculation results of the components of the virtual water are shown in Table 1, it can be seen that the comprehensive effect of the hydrological geochemical reaction is Na+Decrease of K+Decrease of Ca2+Decrease of Mg2+Decrease of SO4 2-Increase of HCO3 -And decreases.
TABLE 1 virtual Water Components calculation results
Figure BDA0003248573740000112
Figure BDA0003248573740000121
Step 5, decoupling the hydrological geochemistry;
the method specifically comprises the following steps: virtual water sample and T1The mass increase and decrease amount of the ith ion in the water sample at the moment is the mass increase and decrease amount of the ith ion under the action of hydrology and geochemistry. Simulating to solve the problem that lake water goes from 'virtual water sample' to T1The relevant hydrological geochemistry in the process of lake water sampling at the moment.
Considering the drastic reduction in the flow rate of the water entering the lake, which forms a large deposit of fine particles at the bottom of the lake, the following effects of alternate adsorption of ions are explained:
2Na++CaX2→Ca2++2NaX (reaction 1)
2K++CaX2→Ca2++2KX (reaction 2)
The main reactions simultaneously participating in the chemical components of lake water comprise dissolving of gypsum, precipitation of dolomite, precipitation of calcite and CO2The overflow of (1) then
Ca2++Mg2++2HCO3 -→CaMg(CO3)2+H2O (reaction 3)
Ca2++HCO3 -→CaCO3+H2O (reaction 4)
H2CO3→CO2+H2O (reaction 5)
Ca2++SO4 2-→CaSO4(reaction 6)
Establishing a system of equations according to equation (4) to solve the unknown number x in equation (5)jI.e. decoupling the influence x of the hydrological geochemistry on the salinity of the body of waterj。
Virtual water sample + reactant ═ T1Time lake water sample + product (4)
Figure BDA0003248573740000122
In the formula, aijIs the stoichiometric number of the element in the ith relative to the mineral in the jth and is equal in value to the number of moles of the ith element resulting from complete dissolution of 1mol of the jth mineral. Corresponds to 6 components (Na)+、K+、Ca2+、Mg2+、SO4 2-And HCO3 -) The 6 mineral elements are Na, K, Ca, Mg, S and C.
Corresponding to the six chemical equations, x is dissolved in each liter of water in the virtual water body1(mmol) of a first mineral (dissolved positive and precipitated negative), x2(mmol) of a second mineral, …, xn(mmol) of the n-th mineral, T is formed1The water quality at the moment, and the increment of the element in the i-th water quality in the end point water quality is b compared with the virtual water samplei(mmol), there is a 1-membered 6-degree system of equations:
Figure BDA0003248573740000131
namely have
Figure BDA0003248573740000132
Solving for x1-x6As shown in Table 2, Na-Ca ion adsorption of-1.13 mmol/L, K-Na ion adsorption of-0.03 mmol/L, dolomite precipitation of 0.92mmol/L, calcite precipitation of 2.4mmol/L, CO20.63mmol/L of escaped gypsum and 0.6mmol/L of dissolved gypsum, thus determining the influence on the salinity of the water body under the hydrological geochemistry action.
TABLE 2 calculation of hydrological geochemical reaction
Figure BDA0003248573740000133
Figure BDA0003248573740000141
And according to the solving result, the dissolution is a positive value, the precipitation is a negative value, the solution is compared with the calculation result of the mineral saturation degree, and the solution is correct if the solution is consistent with the mineral saturation condition.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (5)

1. A calculation method for influence of decoupling evaporation on salt content of a water body in a lake or reservoir is characterized by comprising the following steps:
step 1, acquiring hydrological meteorological data of lakes and reservoirs, and collecting delta T time periods, namely TkTime to Tk+1Constantly water samples and lake and reservoir supply item and drainage item water samples are subjected to water chemical analysis to determine Na+、K+、Ca2+、Mg2+、Cl-、SO4 2-And HCO3 -Concentration;
step 2, establishing a water quantity balance equation and a chloride ion mass conservation equation, and calculating the inflow runoff and the outflow runoff of the underground water;
step 3, calculating TkAnd Tk+1The mineral saturation S of lake water at the moment;
step 4, determining a virtual water sample and decoupling the influence of evaporation;
and step 5, determining the hydrological geochemical action participating in the reaction, establishing a six-element equation of a first order, solving the hydrological geochemical reaction quantity, comparing the hydrological geochemical reaction quantity with the lake water mineral saturation, and decoupling the influence of the hydrological geochemical action.
2. The calculation method for decoupling influence of evaporation on salt content of the water body in the lake and reservoir according to claim 1, wherein in the step 1, the lake and reservoir replenishment items are atmospheric precipitation P, surface runoff replenishment SI and artificial replenishment HI; the lake and reservoir excretion items are evaporation capacity E, surface runoff excretion SO and human development and utilization HO.
3. The method for calculating the influence of the decoupling evaporation on the salinity of the water body in the lake and reservoir according to claim 1, wherein in the step 2, the method specifically comprises the following steps: equations (1) and (2) are obtained according to the law of mass conservation:
Figure FDA0003248573730000011
Figure FDA0003248573730000012
Figure FDA0003248573730000021
wherein GI isThe flow rate of the underground water flowing into the lake is GO, and the delta V is the volume change of the water body in the delta t period of the lake reservoir; clPReduction of chloride ion concentration, Cl, for atmospheric purposesSIReplenishing surface runoff with water chlorine ion concentration, ClGIReplenishing water with chloride ion concentration, Cl, for subsurface runoffHIFor artificially replenishing the water body with the concentration of chloride ions,
Figure FDA0003248573730000022
is the average value of the concentration of chloride ions in the water body of the lake and reservoir in the delta t period, VTkAnd VTk+1Are respectively lake reservoir TkAnd Tk+1Water volume at time, ClTkAnd ClTk+1Are respectively lake reservoir TkAnd Tk+1The chloride ion concentration of the water body at any moment;
and (3) combining the vertical type (1) and the formula (2), and solving to obtain the current stage of the groundwater runoff GI and the groundwater runoff GO.
4. The method for calculating the influence of the decoupling evaporation on the salinity of the water body in the lake and reservoir according to claim 3, wherein in the step 4, the method specifically comprises the following steps:
calculating the end time T according to the law of conservation of massk+1The component value m of the ith (i ═ 1, 2.., 6) corresponding to the water sampleiIncluding Na+、K+、Ca2+、Mg2+、SO4 2-And HCO3 -As shown in formula (3);
Figure FDA0003248573730000023
in the formula, Ai,PConcentration of the ith component in atmospheric precipitation, Ai,SIReplenishment of surface runoff with component concentration i, Ai,GIThe concentration of the ith component of the groundwater runoff into the lake, Ai,HIFor artificial water supplementation of the ith component concentration, ATiIs TiThe concentration of the ith component in the water body in the lake and reservoir at any moment,
Figure FDA0003248573730000024
the concentration mean value of the ith component of the lake and reservoir water body in the delta t period;
from TkTime to Tk+1At any moment, the concentration distribution of each component of the water body in the lake and reservoir is changed to Ai；
Let i component Tk+1The actual observed concentration of the lake water at the moment is Ri,T1；
When A isi>Ri,T1The time indicates that the content of the ith ion is reduced in the water sample at the end moment by hydrologic geochemistry;
when A isi＝Ri,T1The time is that the content of the ith ion is not changed in the water sample at the end moment by hydrologic geochemistry;
when A isi<Ri,T1The time indicates that the content of the ith ion is increased in the water sample at the end moment by the hydrologic geochemistry;
at this time, the water sample composed of each ion under the influence of the evaporation is defined as a virtual water sample.
5. The method for calculating the influence of the decoupling evaporation on the salinity of the water body in the lake and reservoir according to claim 4, wherein in the step 5, the method specifically comprises the following steps:
virtual water sample and Tk+1The mass increase and decrease of the ith ion in the water sample at the moment is the mass increase and decrease of the ion under the action of hydrology and geochemistry, and is recorded as bi(ii) a Simulating to solve the problem that lake water goes from 'virtual water sample' to Tk+1The relevant hydrological geochemistry effect in the process of the lake water sample at the moment is shown as a formula (4);
virtual water sample + reactant ═ Tk+1A lake water sample + a product (4) at the moment;
in the initial body of water, x is dissolved per liter of water1X of a first mineral of (1)2…, xmThe end-point water quality is formed after the n-th mineral, and the increment of the element in the i-th water quality in the end-point water quality is b compared with the initial mixed water qualityiAs shown in formula (5);
Figure FDA0003248573730000031
in the formula, aijIs the stoichiometric number of the element in the ith relative to the mineral in the jth and is equal in value to the number of moles of the ith element resulting from complete dissolution of 1mol of the jth mineral;
selecting j mineral elements, establishing a j-element linear equation, and solving xj，xjPositive values indicate dissolution and negative values indicate precipitation; x is to bejComparing the sign of the mineral solubility S with the sign of the mineral solubility S, if the signs are consistent, indicating that the calculation result is correct, and if the signs are not consistent, indicating that the reactant and the product selected in the formula (4) need to be adjusted, and repeating the step 5 until the calculation result is correct.
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