CN104615885A - Short-term forecasting method for eutrophication shallow lake algae source lake flooding - Google Patents

Abstract

The invention provides a short-term forecasting method for eutrophication shallow lake algae source lake flooding. The method comprises the steps that a plurality of monitoring points are set in a water area where shallow lake flooding is likely to happen so as to measure meteorological parameters and water environment parameters; a space mesh dividing and interpolation algorithm is used for interpolating the water environment parameters of the monitoring points to a whole lake, and space distribution is used as the initial condition of a water quality numerical model; the wind field time and space distribution in the next three days is used as model external stress, a three-dimensional water power-water quality numerical model is driven to conduct calculation, and the time and space distribution of the shallow lake chlorophyll a and the dissolved oxygen concentration in the next three days is obtained; the time and space distribution of the chlorophyll a and the dissolved oxygen concentration is used for being combined with the meteorological parameters, so that a probability empirical formula is established, and the probability of lake flooding in the water area where the lake flooding is likely to happen in the next three days is calculated. For the water area where the lake flooding probability is large, the position and area of lake flooding are further determined.

Description

The short-term earthquake prediction method that property lake, a kind of nutrition enriched shallow lake algae source is general

Technical field

The present invention relates to the short-term earthquake prediction method that property lake, a kind of nutrition enriched shallow lake algae source is general, belong to Environmental Science and Engineering Scientific basis Theory and applications fundamental research technical field.

Background technology

Over nearly 20 years, China's In Middle And Lower Reaches of Changjiang River shallow lake water environmental problems is on the rise, and the breakout of cyanobacteria blooms caused by lake water eutrophication in summer and autumn happens occasionally, and has a strong impact on water quality view, even jeopardizes water supply security." lake is general " that caused by blue-green alga bloom is that lake eutrophication water body breaks out in a large number in algae, to gather and after death, under suitable meteorology, hydrologic condition, under anoxic and anaerobic condition, biochemical reaction is produced with the organism in bed mud, the sulphur ether materials such as release sulfide, form brown-black companion cacodorous " Heisui River group ", thus causing water quality to worsen rapidly, the ecosystem is subject to havoc.For Taihu Lake, in by the end of May, 2007, near the spring factory of Taihu Lake tribute arm of lake Wuxi City south, lake occurs general, Taihu Lake, Wuxi drinking water source area water quality is sharply worsened and smelly, cause Wuxi water supply crisis, nearly 2,000,000 population lives of Wuxi City are had a strong impact on.Between 2008 to 2014 spring and summers, the general phenomenon in the lake of being extended by blue-green alga bloom was never interrupted, and duration 1-6 days are not etc., and wherein maximum flood surface is long-pending can reach 17km ², had a strong impact on the TAIHU LAKE ecosystem.

No matter can predict, be lake eutrophication problem, or the general problem in lake, cannot be solved in a short time at all, all will exist always and threaten shallow lake water environment and water supply security.In order to avoid the generation again of water critical incident; ensure the safety of eutrophic lake potable water; be necessary to develop the general prediction and warning technology of blue-green alga bloom and lake; within the specific limits; Simulation and analysis is carried out to the general generation of blue-green alga bloom and lake, the time of development, spatial distribution characteristic; for the high-speed decision of government department and emergency measure provide theoretical foundation, improve the reply Governance Ability of government, at utmost reduce its ecological hazard and health risk.

At present more for the prediction and warning technical research of blue-green alga bloom, but for the general research in lake, rest on tracing property observation and study mechanism aspect more, really before disaster occurs, be applied to the general prediction and warning in lake and put into practice, and regularly publish the less of the general forecast in lake.Mostly the shallow lake of China is important water head site and tourist district, and whether a large amount of blue-green algaes can pile up at intake or tourist district forms disastrous wawter bloom, affects water quality and view, whether forms lake general, cause water supply crisis, become the problem of square administrative authority delusively.Based on above-mentioned technical background, be necessary to set up workable, an ageing strong prediction and warning method, realize the general probability of happening in lake in summer and autumn, the prediction of the short-term dynamic of generation area and area, thus provide favourable scientific basis for the daily management mission of shallow lake.

Summary of the invention

The object of the present invention is to provide the short-term earthquake prediction method that property lake, a kind of nutrition enriched shallow lake algae source is general.First with the wind field in weather forecast for driving force, solve the three-dimensional hydrodynamic force-water quality couple numerical approach of shallow lake, calculate the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration, then meteorological factor (wind speed, the rainfall etc.) information combining following three days sets up experimental formula, calculate the probability that the general generation lake, territory that easily floods, lake is general, and determine general generation position, lake and area further.

Above-mentioned purpose of the present invention is realized by the technical characteristic of independent claims, and dependent claims develops the technical characteristic of independent claims with alternative or favourable mode.

For reaching above-mentioned purpose, the technical solution adopted in the present invention is as follows:

The short-term earthquake prediction method that property lake, a kind of nutrition enriched shallow lake algae source is general, comprise: the general setting monitoring point, territory that easily floods in shallow lake lake, meteorologic parameter (as temperature, wind speed, wind direction) and water environment parameter (as water temperature, transparency, chlorophyll-a concentration, dissolved oxygen DO solubility and nutrient concentration) are measured; Utilize space lattice to divide and interpolation technique, the water environment parameter of monitoring point is interpolated into full lake, and its space distribution is as the starting condition of Water Quality Numerical Model; Using following three days wind field spatial and temporal distributions as model-driven power, drive three-dimensional hydrodynamic force-Water Quality Numerical Model to carry out computing, obtain the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration; Utilize the spatial and temporal distributions of chlorophyll a and dissolved oxygen concentration, set up probability experimental formula in conjunction with meteorologic parameter, calculate the probability that the following general generation lake, territory that easily floods, three days lakes is general; For there is the larger region of the general probability in lake, determine further general position, lake and area occur.

As further example, the specific implementation of preceding method comprises:

1, the general territory setting monitoring site that easily floods in lake, measures meteorologic parameter and water environment parameter

Based on the understanding in the territory that easily floods to shallow lake, respectively several monitoring points are set paying close attention to lake region, and artificial original position inspection can be carried out.At every bit position place, adopt multi-parameter water quality instrument (YSI6600-V2) (YellowSpring Instruments, USA) water quality parameter is measured, as chlorophyll-a concentration, dissolved oxygen concentration, saturation dissolved oxygen etc., adopt Sai Shi dish method to measure water transparency, and immediately measure the indexs such as temperature, wind speed, wind direction, water temperature.Gather top layer water sample (the 10-30cm degree of depth) 1 liter, the filling insulation can put into immediately in sampling bottle with ice chest of sample, for the mensuration of the indexs such as nitrogen, phosphorus recycling and dissolved organic carbon in laboratory after disembarkation, the analysis of sample is carried out according to lake ecosystem observation procedure.

2, utilize space lattice to divide and interpolation technique, the water environment parameter measured in monitoring point is interpolated into full lake

According to the on-site measurement to the general territory landform of easily flooding in lake, adopt triangular mesh to divide territory, full lake region, grid resolution can according to lake region degree of concern and water front degree of crook, is not set to hundreds of rice to 1 km not etc.Adopt anti-distance weighting interpolation algorithm the water environment parameter value of monitoring site to be interpolated on each computing grid of full lake, obtain the initial distribution situation of full lake water environmental parameter.

3, three-dimensional hydrodynamic force-Water Quality Numerical Model is adopted to calculate the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration.

1) hydrodynamic model

The three-dimensional hydrodynamic force equation in conserva tion form group describing shallow lake water movement is:

$\frac{\∂\mathrm{\ζ}}{\∂t}+\frac{\∂\mathrm{Du}}{\∂x}+\frac{\∂\mathrm{Dv}}{\∂y}+\frac{\∂w}{\∂\mathrm{\σ}}=0$

$\begin{array}{c}\frac{\∂\mathrm{uD}}{\∂t}+\frac{{\∂u}^{2}D}{\∂x}+\frac{\∂\mathrm{uvD}}{\∂y}+\frac{\∂\mathrm{uw}}{\∂\mathrm{\σ}}-\mathrm{fvD}=-\mathrm{gD}\frac{\∂\mathrm{\ζ}}{\∂x}-\frac{\mathrm{gD}}{{\mathrm{\ρ}}_0}[\frac{\∂}{\∂x}\left(D{\∫}_{\mathrm{\σ}}^0\mathrm{\ρd}{\mathrm{\σ}}^{\′}\right)+\mathrm{\σ\ρ}\frac{\∂D}{\∂x}]\\ +\frac{1}{D}\frac{\∂}{\∂\mathrm{\σ}}\left(K_m\frac{\∂u}{\∂\mathrm{\σ}}\right)+\frac{\∂}{\∂x}\left[{2A}_{m}D\frac{\∂u}{\∂x}\right]+\frac{\∂}{\∂y}\left[A_{m}D(\frac{\∂u}{\∂y}+\frac{\∂v}{\∂x})\right]\end{array}$

$\begin{array}{c}\frac{\∂\mathrm{vD}}{\∂t}+\frac{\∂\mathrm{uv}D}{\∂x}+\frac{\∂v^{2}D}{\∂y}+\frac{\∂\mathrm{vw}}{\∂\mathrm{\σ}}+\mathrm{fuD}=-\mathrm{gD}\frac{\∂\mathrm{\ζ}}{\∂y}-\frac{\mathrm{gD}}{{\mathrm{\ρ}}_0}[\frac{\∂}{\∂y}\left(D{\∫}_{\mathrm{\σ}}^0\mathrm{\ρd}{\mathrm{\σ}}^{\′}\right)+\mathrm{\σ\ρ}\frac{\∂D}{\∂y}]\\ +\frac{1}{D}\frac{\∂}{\∂\mathrm{\σ}}\left(K_m\frac{\∂v}{\∂\mathrm{\σ}}\right)+\frac{\∂}{\∂x}\left[A_{m}D(\frac{\∂u}{\∂y}+\frac{\∂v}{\∂x})\right]+\frac{\∂}{\∂y}\left[2A_{m}D\frac{\∂v}{\∂y}\right]\end{array}$

In formula: u, v, w are the velocity component along x, y, σ direction; ζ is water level; D=h+ ζ is the full depth of water; ρ is density; G is acceleration of gravity; F is Ke Shi coefficient; A _m, K _mfor level, vertical turbulent viscosity.

The finite volume model under unstructured grids is adopted to solve governing equation.Domain plane adopts unstructured grids (triangle) subdivision, makes computation bound more accurately matching bank circle; Vertical direction adopts σ coordinate conversion, makes whole waters have identical vertical layered number.When governing equation is, the N-S equation of homogenizing closes submodel with the turbulent flow closing it, and discrete method adopts limited bulk thought, and all physics variable set ups are at the center of triangular unit.The integrated form on each triangular unit of inside and outside mould isolation technics to governing equation group is adopted to carry out numerical solution, first solve two-dimentional external schema gain freedom surface and vertical mean flow rate, wherein the time discrete of external schema adopts newton's forward difference form, and spatial spreading adopts the Roe type numerical flux of second order accuracy and the burst constant of single order precision to approach reconstruct mode; Solve three-dimensional internal schema again and obtain three-dimensional flow field, wherein time discrete adopts newton's forward difference form, and space convective term adopts the upstreame scheme of second order accuracy, and vertical diffusion item adopts explicit form.Because interior external mold time step is different, consistency check that is outer, internal mold flow field must be carried out in computation process in each internal mold step-length.

2) water quality model

Under hydrodynamical particular impact, the transport equation of water quality parameter concentration is:

$\frac{\∂\mathrm{DC}}{\∂t}+\frac{\∂\mathrm{DuC}}{\∂x}+\frac{\∂\mathrm{DvC}}{\∂y}+\frac{\∂\mathrm{\ωC}}{\∂\mathrm{\σ}}=\frac{\∂}{\∂x}\left(A_{H}D\frac{\∂C}{\∂X}\right)+\frac{\∂}{\∂y}\left(A_{H}D\frac{\∂C}{\∂y}\right)+\frac{\∂}{\∂\mathrm{\σ}}\left(\frac{K_H}{D}\frac{\∂C}{\∂\mathrm{\σ}}\right)+s_K$

Wherein C representative species concentration.When C is chlorophyll-a concentration, dynamic response item S _kconsider the growth of algae, death and settlement action respectively.When C is dissolved oxygen concentration, dynamic response item S _kto consider in air oxygen enrichment, water body photosynthesis respectively to the increase of dissolved oxygen DO and hydrophyte respiration, BOD degraded, nitration reaction oxygen consumption and bed mud oxygen demand to the minimizing effect of dissolved oxygen DO.The solution procedure of water quality parameter Transport Model takes the discrete way identical with hydrodynamic model internal schema.

3) model-driven power

The External Force Acting driving hydrodynamic force-water Quality Coupling Model to run is mainly the wind-stress (V of following three days _x, V _y), V _x, V _ybe respectively the air speed value on x, y direction, unit is m/s.

Wind-stress obtain manner: at Chinese weather net

The wind of Beaufort force of the following three days wind-force of (http://www.weather.com.cn/html/weather/101190201.shtml) upper inquiry and wind direction, according to the transformation rule of table 1, convert the wind-force wind of Beaufort force of every day in following weather forecast in three days to resultant wind velocity value V, according to the transformation rule of table 2, convert the wind direction of every day in following weather forecast in three days to angle θ, then V _x=-Vcos θ, V _y=-Vsin θ.

The conversion of table 1 wind of Beaufort force and wind speed

Wind of Beaufort force	1	2	3	4	5
						Corresponding wind speed (m/s)	0.3-1.5	1.6-3.3	3.4-5.4	5.5-7.9	8.0-10.7

The conversion of table 2 wind direction and the number of degrees

Wind direction	East	The southeast	South	Southwest	West	Northwest	North	Northeast
									Angle	90	135	180	225	270	315	0	45

4) the computing flow process of model

By model calculation, obtain following three days full lake each computing grid inner chlorophyll a and the time dependent numerical value of dissolved oxygen concentration, and then obtain the spatial and temporal distributions in full lake.

4, set up probability experimental formula, calculate the probability that the following general generation lake, territory that easily floods, three days lakes is general

The general generation in lake is relevant to several factors, but in short-time forecast, the factors such as the water nutrition affecting the general generation in lake on a larger time scale can not be considered, only filter out the effect of the Measures of Algae in Water Body concentration of the general generation in rapid contribution lake in several days, dissolved oxygen concentration and the meteorological factor such as wind speed, rainfall, the probability forecast model that therefore property lake in algae source is general can be expressed as

F＝f ₁(N1 _t)*f ₂(V)*f ₃(R)*f ₄(N2 _t)

Wherein f ₁(N1 _t) be the probability caused by t amount of algae, f ₂(V) probability for being caused by wind friction velocity, f ₃(R) probability for being caused by condition of raining, f ₄(N2 _t) be the probability caused by t dissolved oxygen DO solubility.Four kinds of probability carry out assignment by table 3 respectively.The each computing grid in full lake utilizes aforementioned probability forecast model, the probability distribution of the general generation in Quan Hu lake can be obtained.

The corresponding table of table 3 chlorophyll, dissolved oxygen content, wind speed, rainfall and the general probability of happening in lake

Chlorophyll (μ g/L)	f(N1 t)	Wind-force (wind speed m/s)	f(V)	Rainfall	f(R)	DO(mg/L)	f(N2 t)
								More than 60	1	1-2 level (0.3-3.3)	1	Fine, cloudy	1	1.0	1
50	0.9	3 grades (3.4-5.4)	0.9	Cloudy, light rain	0.9	2.0	0.8
								40	0.8	4 grades (5.5-7.9)	0.8	Shower, thunder shower	0.8	4.0	0.6
20	0.6	5 grades (8.0-10.7)	0.7	Moderate rain	0.7	6.0	0.4

10

0.4

More than 5 grades (> 10.8)

0.5

In, large, heavy rain

0

8.0

0

5, for there is the larger region of the general probability in lake, determine further general position, lake and area occur

For paid close attention to Fan Yifa lake region, lake, can be divided into some sections in advance, each section comprises some computing grids.The probability of the general generation in lake on the computing grid utilizing aforementioned probability forecast model to calculate respectively to cover in every section waters, if this section exists the grid that probability is greater than 50%, then forecasts that generation lake, this section of waters is general; , namely there is the general area in lake in the grid area sum that in this section, probability is greater than 50%.

From the above technical solution of the present invention shows that, the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source of the present invention is general, based on deterministic models principle, according to algae, dissolved oxygen concentration and various physical agent, the interaction relationship of Some Circulating Factors, set up hydrodynamics of lake-water quality Numerical coupling model, and under suitable starting condition and boundary condition, in conjunction with meteorologic parameter, utilize this core of mathematics Basic equation group of Numerical Methods Solve coupling model, obtain the distribution of algae bio amount and dissolved oxygen concentration on different time and space scale, thus realize the general prediction in lake.

In annual shallow lake lake general summer and autumn occurred frequently (April-October), can set and carry out the general prediction in following three days lakes with Thursday according to step 1-5 on every Mondays, forecast result is made into lake general monitoring and warning half weekly, be sent to lake administrative authority at different levels, can effectively for administrative authority's high-speed decision and formulation emergency measure provide theoretical foundation, improve the reply Governance Ability of government, at utmost reduce its ecological hazard and health risk, the daily management mission for shallow lake provides favourable scientific basis.

As long as should be appreciated that aforementioned concepts and all combinations of extra design described in further detail below can be regarded as a part for subject matter of the present disclosure when such design is not conflicting.In addition, all combinations of theme required for protection are all regarded as a part for subject matter of the present disclosure.

The foregoing and other aspect of the present invention's instruction, embodiment and feature can be understood by reference to the accompanying drawings from the following description more all sidedly.Feature and/or the beneficial effect of other additional aspect of the present invention such as illustrative embodiments will be obvious in the following description, or by learning in the practice of the embodiment according to the present invention's instruction.

Accompanying drawing explanation

Accompanying drawing is not intended to draw in proportion.In the accompanying drawings, each identical or approximately uniform ingredient illustrated in each figure can represent with identical label.For clarity, in each figure, not each ingredient is all labeled.Now, the embodiment of various aspects of the present invention also will be described with reference to accompanying drawing by example, wherein:

Fig. 1 is anti-distance weighting interpolation algorithm schematic diagram.

Fig. 2 is the three-dimensional hydrodynamic force-Water Quality Numerical Model calculation flow chart of shallow lake.

Fig. 3 is general inspection region, lake, Taihu Lake and monitoring station schematic diagram.

Fig. 4 is lake, Taihu Lake general forecast model stress and strain model figure.

Fig. 5 is Taihu Lake chlorophyll concentration and the full lake interpolation distribution of dissolved oxygen concentration on June 12nd, 2014.

Fig. 6 is the model prediction distribution plan of 13-15 in June day Taihu Lake chlorophyll-a concentration and dissolved oxygen concentration.

Fig. 7 is the determination of Taihu Lake lake general probability of happening distribution plan on June 13 and the general occurring area in lake.

Fig. 8 is that the segmentation of general emphasis estimation range, lake, Taihu Lake divides.

Fig. 9 is Taihu Lake blue-green algae and lake general monitoring and warning half weekly model.

In aforementioned diagram 1-9, each coordinate, mark or other expressions, be known in the field, do not repeat in this example again.

Embodiment

In order to more understand technology contents of the present invention, institute's accompanying drawings is coordinated to be described as follows especially exemplified by specific embodiment.

Each side with reference to the accompanying drawings to describe the present invention in the disclosure, shown in the drawings of the embodiment of many explanations.Embodiment of the present disclosure must not be intended to comprise all aspects of the present invention.Be to be understood that, multiple design presented hereinbefore and embodiment, and those designs described in more detail below and embodiment can in many ways in any one is implemented, this should be design disclosed in this invention and embodiment is not limited to any embodiment.In addition, aspects more disclosed by the invention can be used alone, or otherwisely anyly appropriately combinedly to use with disclosed by the invention.

The present invention gives property lake, a kind of nutrition enriched shallow lake algae source general short-term earthquake prediction method, based on deterministic models principle, according to the interaction relationship of algae, dissolved oxygen concentration and various physical agent, Some Circulating Factors, set up hydrodynamics of lake-water quality Numerical coupling model, and under suitable starting condition and boundary condition, in conjunction with meteorologic parameter, utilize this core of mathematics Basic equation group of Numerical Methods Solve coupling model, obtain the distribution of algae bio amount and dissolved oxygen concentration on different time and space scale, thus realize the general prediction in lake.Based on the short-term forecasting result that the method realizes, can in annual shallow lake lake general summer and autumn occurred frequently (April-October), be set to and carry out the general prediction in following three days lakes with Thursday according to step 1-5 on every Mondays, forecast result is made into lake general monitoring and warning half weekly, be sent to lake administrative authority at different levels, can effectively for administrative authority's high-speed decision and formulation emergency measure provide theoretical foundation, improve the reply Governance Ability of government, at utmost reduce its ecological hazard and health risk, daily management mission for shallow lake provides favourable scientific basis.

As the preferably embodiment that the present invention proposes, above-mentioned purpose is achieved in that the general setting monitoring point, territory that easily floods in shallow lake lake, measures meteorologic parameter (temperature, wind speed, wind direction) and water environment parameter (water temperature, transparency, chlorophyll-a concentration, dissolved oxygen DO solubility and nutrient concentration); Then, utilize space lattice to divide and interpolation technique, the water environment parameter of monitoring point is interpolated into full lake, and its space distribution is as the starting condition of Water Quality Numerical Model; Again using following three days wind field spatial and temporal distributions as model-driven power, drive three-dimensional hydrodynamic force-Water Quality Numerical Model to carry out computing, obtain the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration; The spatial and temporal distributions of recycling chlorophyll a and dissolved oxygen concentration, sets up probability experimental formula in conjunction with meteorologic parameter, calculates the probability that the following general generation lake, territory that easily floods, three days lakes is general; Finally, for there is the larger region of the general probability in lake, determine further general position, lake and area occur.

The exemplarily description of property, shown in accompanying drawing, is specifically described the enforcement of preceding method.

1, the general territory setting monitoring site that easily floods in lake, measures meteorologic parameter and water environment parameter

Based on the understanding in the territory that easily floods to shallow lake, respectively several monitoring points are set paying close attention to lake region, and artificial original position inspection can be carried out.At every bit position place, adopt multi-parameter water quality instrument (YSI6600-V2) (YellowSpring Instruments, USA) water quality parameter is measured, as chlorophyll-a concentration, dissolved oxygen concentration, saturation dissolved oxygen etc., adopt Sai Shi dish method to measure water transparency, and immediately measure the indexs such as temperature, wind speed, wind direction, water temperature.Gather top layer water sample (the 10-30cm degree of depth) 1 liter, the filling insulation can put into immediately in sampling bottle with ice chest of sample, for the mensuration of the indexs such as nitrogen, phosphorus recycling and dissolved organic carbon in laboratory after disembarkation, the analysis of sample is carried out according to lake ecosystem observation procedure.

2, utilize space lattice to divide and interpolation technique, the water environment parameter measured in monitoring point is interpolated into full lake

According to the on-site measurement to the general territory landform of easily flooding in lake, adopt triangular mesh to divide territory, full lake region, grid resolution can according to lake region degree of concern and water front degree of crook, and the scope of setting is between 100 meters to 1 km.In this example, preferably adopt anti-distance weighting interpolation algorithm the water environment parameter value of monitoring site to be interpolated on each computing grid of full lake, obtain the initial distribution situation of full lake water environmental parameter.

The basic implementation method of anti-distance weighting interpolation algorithm is (for chlorophyll-a concentration): as shown in Figure 1, if the chlorophyll-a concentration of a certain grid element center point O is unknown, for choosing the nearest monitoring point of 3-5 distance O point, is weighted O point.First need 3-5 the monitoring point that detection range O point is nearest: 1) be that search radius draws circle with d1, have A, B, C, D, E, F to be included in circle totally 6 monitoring points, illustrate that radius d1 value is bigger than normal; 2) reduced radius is d2 (such as getting d1/2), have A, C totally 2 points be included in circle, illustrate that radius d2 is less than normal; 3) expanding radius is d3 (such as getting d2*1.7), have A, B, C totally 3 points be included in circle, search terminates; If counted too much, then 2 are returned) continue search; If counted not, then 3 are returned) continue search.

After monitoring point is found out, near according to distance, then weight is little, distance, then the principle that weight is large, calculates the chlorophyll-a concentration of O point, that is:

${\mathrm{Chla}}_O=\frac{{\mathrm{Chla}}_A*\frac{1}{r_1}+{\mathrm{Chla}}_B*\frac{1}{r_2}+{\mathrm{Chla}}_C*\frac{1}{r_3}}{\frac{1}{r_1}+\frac{1}{r_2}+\frac{1}{r_3}}---\left(1\right)$

Wherein Chla _o, Chla _a, Chla _b, Chla _cthe chlorophyll-a concentration value of representative point O, A, B, C respectively, r ₁, r ₂, r ₃representative point O is apart from the distance of A, B, C 3 respectively.

3, three-dimensional hydrodynamic force-Water Quality Numerical Model is adopted to calculate the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration.

1) hydrodynamic model

The three-dimensional hydrodynamic force equation in conserva tion form group describing shallow lake water movement is:

$\frac{\∂\mathrm{\ζ}}{\∂t}+\frac{\∂\mathrm{Du}}{\∂x}+\frac{\∂\mathrm{Dv}}{\∂y}+\frac{\∂w}{\∂\mathrm{\σ}}=0---\left(2\right)$

$\begin{array}{c}\frac{\∂\mathrm{uD}}{\∂t}+\frac{{\∂u}^{2}D}{\∂x}+\frac{\∂\mathrm{uvD}}{\∂y}+\frac{\∂\mathrm{uw}}{\∂\mathrm{\σ}}-\mathrm{fvD}=-\mathrm{gD}\frac{\∂\mathrm{\ζ}}{\∂x}-\frac{\mathrm{gD}}{{\mathrm{\ρ}}_0}[\frac{\∂}{\∂x}\left(D{\∫}_{\mathrm{\σ}}^0\mathrm{\ρd}{\mathrm{\σ}}^{\′}\right)+\mathrm{\σ\ρ}\frac{\∂D}{\∂x}]\\ +\frac{1}{D}\frac{\∂}{\∂\mathrm{\σ}}\left(K_m\frac{\∂u}{\∂\mathrm{\σ}}\right)+\frac{\∂}{\∂x}\left[{2A}_{m}D\frac{\∂u}{\∂x}\right]+\frac{\∂}{\∂y}\left[A_{m}D(\frac{\∂u}{\∂y}+\frac{\∂v}{\∂x})\right]\end{array}---\left(3\right)$

$\begin{array}{c}\frac{\∂\mathrm{vD}}{\∂t}+\frac{\∂\mathrm{uv}D}{\∂x}+\frac{\∂v^{2}D}{\∂y}+\frac{\∂\mathrm{vw}}{\∂\mathrm{\σ}}+\mathrm{fuD}=-\mathrm{gD}\frac{\∂\mathrm{\ζ}}{\∂y}-\frac{\mathrm{gD}}{{\mathrm{\ρ}}_0}[\frac{\∂}{\∂y}\left(D{\∫}_{\mathrm{\σ}}^0\mathrm{\ρd}{\mathrm{\σ}}^{\′}\right)+\mathrm{\σ\ρ}\frac{\∂D}{\∂y}]\\ +\frac{1}{D}\frac{\∂}{\∂\mathrm{\σ}}\left(K_m\frac{\∂v}{\∂\mathrm{\σ}}\right)+\frac{\∂}{\∂x}\left[A_{m}D(\frac{\∂u}{\∂y}+\frac{\∂v}{\∂x})\right]+\frac{\∂}{\∂y}\left[2A_{m}D\frac{\∂v}{\∂y}\right]\end{array}---\left(4\right)$

In formula: u, v, w are the velocity component along x, y, σ direction; ζ is water level; D=h+ ζ is the full depth of water; ρ is density; G is acceleration of gravity; F is Ke Shi coefficient; A _m, K _mfor level, vertical turbulent viscosity.

The finite volume model under unstructured grids is adopted to solve governing equation.Domain plane adopts unstructured grids (triangle) subdivision, makes computation bound more accurately matching bank circle; Vertical direction adopts σ coordinate conversion, makes whole waters have identical vertical layered number.When governing equation is, the N-S equation of homogenizing closes submodel with the turbulent flow closing it, and discrete method adopts limited bulk thought, and all physics variable set ups are at the center of triangular unit.The integrated form on each triangular unit of inside and outside mould isolation technics to governing equation group is adopted to carry out numerical solution, first solve two-dimentional external schema gain freedom surface and vertical mean flow rate, wherein the time discrete of external schema adopts newton's forward difference form, and spatial spreading adopts the Roe type numerical flux of second order accuracy and the burst constant of single order precision to approach reconstruct mode; Solve three-dimensional internal schema again and obtain three-dimensional flow field, wherein time discrete adopts newton's forward difference form, and space convective term adopts the upstreame scheme of second order accuracy, and vertical diffusion item adopts explicit form.Because interior external mold time step is different, consistency check that is outer, internal mold flow field must be carried out in computation process in each internal mold step-length.

2) water quality model

Under hydrodynamical particular impact, the transport equation of water quality parameter concentration is:

$\frac{\∂\mathrm{DC}}{\∂t}+\frac{\∂\mathrm{DuC}}{\∂x}+\frac{\∂\mathrm{DvC}}{\∂y}+\frac{\∂\mathrm{\ωC}}{\∂\mathrm{\σ}}=\frac{\∂}{\∂x}\left(A_{H}D\frac{\∂C}{\∂X}\right)+\frac{\∂}{\∂y}\left(A_{H}D\frac{\∂C}{\∂y}\right)+\frac{\∂}{\∂\mathrm{\σ}}\left(\frac{K_H}{D}\frac{\∂C}{\∂\mathrm{\σ}}\right)+s_K---\left(5\right)$

Wherein: C representative species concentration.When C is chlorophyll-a concentration, dynamic response item S _kconsider the growth of algae, death and settlement action respectively.When C is dissolved oxygen concentration, dynamic response item S _kto consider in air oxygen enrichment, water body photosynthesis respectively to the increase of dissolved oxygen DO and hydrophyte respiration, BOD degraded, nitration reaction oxygen consumption and bed mud oxygen demand to the minimizing effect of dissolved oxygen DO.The solution procedure of water quality parameter Transport Model takes the discrete way identical with hydrodynamic model internal schema.

3) model-driven power

The External Force Acting driving hydrodynamic force-water Quality Coupling Model to run is mainly the wind-stress (V of following three days _x, V _y), V _x, V _ybe respectively the air speed value on x, y direction, unit is m/s.

Wind-stress obtain manner: at Chinese weather net

The wind of Beaufort force of the following three days wind-force of (http://www.weather.com.cn/html/weather/101190201.shtml) upper inquiry and wind direction, according to the transformation rule of table 1, convert the wind-force wind of Beaufort force of every day in following weather forecast in three days to resultant wind velocity value V, according to the transformation rule of table 2, convert the wind direction of every day in following weather forecast in three days to angle θ, then V _x=-Vcos θ, V _y=-Vsin θ.

The conversion of table 1 wind of Beaufort force and wind speed

Wind of Beaufort force	1	2	3	4	5
						Corresponding wind speed (m/s)	0.3-1.5	1.6-3.3	3.4-5.4	5.5-7.9	8.0-10.7

The conversion of table 2 wind direction and the number of degrees

Wind direction	East	The southeast	South	Southwest	West	Northwest	North	Northeast
									Angle	90	135	180	225	270	315	0	45

4) the computing flow process of model

Flow process as shown in Figure 2, by model calculation, obtains following three days full lake each computing grid inner chlorophyll a and the time dependent numerical value of dissolved oxygen concentration, and then obtains the spatial and temporal distributions in full lake.

4, set up probability experimental formula, calculate the probability that the following general generation lake, territory that easily floods, three days lakes is general

The general generation in lake is relevant to several factors, but in short-time forecast, the factors such as the water nutrition affecting the general generation in lake on a larger time scale can not be considered, only filter out the effect of the Measures of Algae in Water Body concentration of the general generation in rapid contribution lake in several days, dissolved oxygen concentration and the meteorological factor such as wind speed, rainfall, the probability forecast model that therefore property lake in algae source is general can be expressed as

F＝f ₁(N1 _t)*f ₂(V)*f ₃(R)*f ₄(N2 _t) (6)

Wherein f ₁(N1 _t) be the probability caused by t amount of algae, f ₂(V) probability for being caused by wind friction velocity, f ₃(R) probability for being caused by condition of raining, f ₄(N2 _t) be the probability caused by t dissolved oxygen DO solubility.Four kinds of probability carry out assignment by table 3 respectively.The each computing grid in full lake utilizes aforementioned probability forecast model, the probability distribution of the general generation in Quan Hu lake can be obtained.

The corresponding table of table 3 chlorophyll, dissolved oxygen content, wind speed, rainfall and the general probability of happening in lake

Chlorophyll (μ g/L)	f(N1 t)	Wind-force (wind speed m/s)	f(V)	Rainfall	f(R)	DO(mg/L)	f(N2 t)
								More than 60	1	1-2 level (0.3-3.3)	1	Fine, cloudy	1	1.0	1
50	0.9	3 grades (3.4-5.4)	0.9	Cloudy, light rain	0.9	2.0	0.8
								40	0.8	4 grades (5.5-7.9)	0.8	Shower, thunder shower	0.8	4.0	0.6
20	0.6	5 grades (8.0-10.7)	0.7	Moderate rain	0.7	6.0	0.4
								10	0.4	More than 5 grades (> 10.8)	0.5	In, large, heavy rain	0	8.0	0

5, for there is the larger region of the general probability in lake, determine further general position, lake and area occur

For paid close attention to Fan Yifa lake region, lake, can be divided into some sections in advance, each section comprises some computing grids.The probability of the general generation in lake on the computing grid utilizing formula (6) to calculate respectively to cover in every section waters, if this section exists the grid that probability is greater than 50%, then forecasts that generation lake, this section of waters is general; , namely there is the general area in lake in the grid area sum that in this section, probability is greater than 50%.

Cited below but be not in the example of exclusiveness, for the monitoring and prediction in the general territory that easily floods, lake, Taihu Lake, illustrate the enforcement of preceding method.

Step 1, in lake general easily flood territory setting monitoring site, on-site measurement is carried out to meteorologic parameter and water environment parameter.

In this example, based on the understanding to the general territory that easily floods, lake, Taihu Lake, respectively in Hu Xi, Zhu Shan gulf, Mei Liang gulf, tribute arm of lake and five lake regions such as water head site, east, lake arrange 24 monitoring points, as shown in Figure 3.Thursday on June 12nd, 2014, basic data is provided in order to give the general forecast in lake on the same day, and to the water quality of each emphasis lake region, Taihu Lake and lake, general a situation arises comprehensive grasp, drives inspection speedboat, successively carry out field observation and measurement to 24 inspection point positions along the route shown in Fig. 3.At every bit position place, adopt multi-parameter water quality instrument (YSI6600-V2) (YellowSpring Instruments, USA) water quality parameters such as chlorophyll-a concentration, dissolved oxygen concentration, saturation dissolved oxygen are measured, adopt Sai Shi dish method to measure water transparency, and immediately measure the indexs such as temperature, wind speed, wind direction, water temperature.The each indication information measured is as shown in table 4.Gather top layer water sample (the 10-30cm degree of depth) 1 liter, the filling insulation can put into immediately in sampling bottle with ice chest of sample, for the mensuration of the indexs such as nitrogen, phosphorus recycling and dissolved organic carbon in laboratory after disembarkation, the analysis of sample is carried out according to lake ecosystem observation procedure.The each achievement data measured is as shown in table 5.

Step 2, the water environment parameter measured in monitoring point is interpolated into the starting condition of full lake as numerical model.

According to the on-site measurement to the general territory landform of easily flooding in lake, Taihu Lake, full lake is divided into 6353 computing grids, as shown in Figure 4.Wherein as west regions and the northern lake region in the general territory that easily floods, lake, grid resolution is ≈ 300m, and all the other waters grid resolution are ≈ 1000m.Adopt anti-distance weighting interpolation algorithm the water environment parameter value of 24 monitoring sites to be interpolated on the computing grid of 6353, full lake, obtain the full lake initial distribution of chlorophyll-a concentration, dissolved oxygen concentration, as shown in Figure 5.

According to the weather forecast that Chinese weather shows on the net, June, 13-15 Pu Fu wind direction wind scale was respectively northeaster 2 grades, east wind 2 grades and east wind 2 grades, according to the conversion principle of table 1 and table 2, and the wind speed V=2.5m/s of three days, 2.5m/s, 2.5m/s; Wind direction θ=45,90,90.

The spatial and temporal distributions of step 3, calculating 13-15 in June day Taihu Lake chlorophyll-a concentration and dissolved oxygen concentration.

Bring data ready in step 2 into three-dimensional hydrodynamic force-water quality model respectively, calculate according to the flow process shown in Fig. 2, obtain following three days full lake each computing grid inner chlorophyll a and the time dependent numerical value of dissolved oxygen concentration, namely obtain the spatial and temporal distributions in full lake, as shown in Figure 6.

Step 4, to calculate on each grid the general probability in following generation lake, three days Taihu Lake.

According to the weather forecast that Chinese weather shows on the net, 13-15 in June day wind speed is 2 grades, and weather is respectively fine to cloudy, fine to cloudy, cloudy, the table of comparisons 3, f (V)=1.0, f (R) _max=1.0; If for No. i-th grid, Chla _i=25.2 μ g/L, DO _i=1.5mg/L, then f (N1 _t)=0.6, f (N2 _t)=1.0, utilize formula (6), and the general probability in lake occurs No. i-th grid

F＝f ₁(N1 _t)*f ₂(V)*f ₃(R)*f ₄(N2 _t)＝0.6

Using formula (6) on 6353 grids, can obtain the probability distribution that generation lake, full Taihu Lake is general, as shown in Figure 7.

Step 5, determine general position, lake and area occur according to probability distribution.

As shown in Figure 8,4 sections are divided into by easily there is general Zhu Shan gulf, lake and offshore 2km scope waters, western coastal belt, too Gehu port is the 1st section (too Gehu husky pool section) to Sha Tang port, it is the 2nd section (the husky pool symbol section of showing disrespect on) that port is shown disrespect on to symbol in Sha Tang port, it is the 3rd section (symbol shows disrespect on old eastern section) to old Donggang City that symbol shows disrespect on port, and old Donggang City is the 4th section (old eastern eight room sections) to eight ports, room; Intake coastal belt, tribute arm of lake north offshore 2 kilometer range is divided into 2 sections, and Wu Tang Men port is the 5th section (Wu pool subsegment in the ninth of the ten Heavenly Stems) to sub-port in the ninth of the ten Heavenly Stems, and Li He is the 6th section (Li He is the section of opening newly) to newly opening port; Using coastal belt, Mei Liang gulf as the 7th section.

According to the probability distribution that generation lake in Taihu Lake in step 4 is general, if this section exists the grid that probability is greater than 50%, then forecast that generation lake, this section of waters is general; , namely there is the general area in lake in the grid area sum that in this section, probability is greater than 50%.As shown in Figure 7, the probability that there is grid generation lake general in the section of Mei Liang gulf is 60%, therefore forecasts that Mei Liang gulf, at following three days, lake occurs general.Wherein, the grid that probability is greater than 50% about has 5-10, is 0.3*0.3/2=0.045km according to a grid area ²calculate, area lake occurring general in following three days is 0.2-0.5km ².

According to the content of operation of step 1-step 5, later stage can be made into " Taihu Lake blue-green algae and lake general monitoring and warning half weekly " (as shown in Figure 9), be sent to lake administrative authority at different levels, the daily management mission not being only Taihu Lake provides favourable scientific basis, and the reply Governance Ability of government can be improved, before the general generation in lake, formulate effective emergency measure, at utmost reduce the general ecological hazard in lake and health risk.

Although the present invention with preferred embodiment disclose as above, so itself and be not used to limit the present invention.Persond having ordinary knowledge in the technical field of the present invention, without departing from the spirit and scope of the present invention, when being used for a variety of modifications and variations.Therefore, protection scope of the present invention is when being as the criterion depending on those as defined in claim.

The inspection of table 5 Taihu Lake on June 12 nitrogen, phosphorus recycling and BOD data

Numbering	BOD(mg/L)	NO 2-N(mg/L)	NO3-N(mg/L)	PO4-P(mg/L)	NH4-N(mg/L)
						8	3.4439	0.1518	2.2806	0.098124	0.606
1	1.9833	0.0527	1.3734	0.019069	0.155
						2	4.6206	0.2207	1.9498	0.083676	0.457
3	2.4896	0.0809	1.7849	0.176241	0.202
						4	3.2435	0.1271	1.8707	0.122338	0.364
5	2.4256	0.094	1.8848	0.049762	0.116
						6	3.6636	0.2237	1.9171	0.062857	0.391
7	4.1060	0.183	1.2418	0.073043	1.637
						9	3.8945	0.1994	1.5592	0.093719	1.552
21	3.4077	0.2028	1.8087	0.051788	1.061
						22	3.1545	0.1839	2.6873	0.074975	0.471
10	2.7344	0.0683	1.8043	0.068473	0.206
						11	2.6482	0.0554	1.5691	0.034347	0.07
12	2.1920	0.0215	1.2428	0.089072	0.108
						13	2.2003	0.0422	1.3855	0.025622	0.067
14	2.3422	0.041	1.1077	0.045403	0.179
						15	1.6022	0.011	1.0688	0.012488	0.075
16	1.3768	0.0129	1.0534	0.011933	0.026
						23	1.4241	0.0147	1.2475	0.016722	0.039
24	1.5215	0.0126	1.3302	0.015977	0.069

Claims (6)

1. the short-term earthquake prediction method that property lake in nutrition enriched shallow lake algae source is general, is characterized in that, the realization of the method comprises the following steps:

1) the general territory setting monitoring site that easily floods in shallow lake lake, measures meteorologic parameter and water environment parameter;

2) utilize space lattice to divide and interpolation algorithm, the water environment parameter measured in monitoring point is interpolated into full lake, and its space distribution is as the starting condition of Water Quality Numerical Model;

3) using following three days wind field spatial and temporal distributions as model-driven power, drive three-dimensional hydrodynamic force-Water Quality Numerical Model to carry out computing, obtain the spatial and temporal distributions of following three days shallow lake chlorophyll as and dissolved oxygen concentration;

4) utilize the spatial and temporal distributions of chlorophyll a and dissolved oxygen concentration, set up probability experimental formula in conjunction with meteorologic parameter, calculate the probability that the following general generation lake, territory that easily floods, three days lakes is general;

5) for there is the larger region of the general probability in lake, determine further general position, lake and area occur.

2. the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source according to claim 1 is general, it is characterized in that, in described step 1), water environment parameter comprises water temperature, transparency, chlorophyll-a concentration, dissolved oxygen concentration, saturation dissolved oxygen, nitrogen, phosphorus recycling index, meteorologic parameter comprises temperature, wind speed, wind direction index, on-the-spot water-quality determination instrument is multi-parameter water quality instrument, and the analysis of sample is carried out according to lake ecosystem observation procedure.

3. the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source according to claim 1 is general, it is characterized in that, described step 2) in, space lattice divides and adopts triangular mesh, grid resolution is according to the degree of concern of lake region and water front degree of crook, the scope of setting is between 100 meters to 1 km, and described interpolation algorithm adopts anti-distance weighting interpolation algorithm.

4. the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source according to claim 1 is general, is characterized in that, in described step 3), adopts coordinate vertical layered, limited bulk discrete method, interior external mold separation method, dry wet point moving boundary method, solve the three-dimensional hydrodynamic force-Water Quality Numerical Model describing shallow lake water movement and material concentration and transport.

5. the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source according to claim 1 is general, it is characterized in that, in described step 4), in short-time forecast, consider generally with lake to be related water body Determination of Chlorophyll a concentration, dissolved oxygen concentration and wind speed close, the effect of rainfall meteorological factor, set up the experimental formula of the general probability of happening in property lake, algae source.

6. the short-term earthquake prediction method that property lake, nutrition enriched shallow lake algae source according to claim 1 is general, it is characterized in that, in described step 5), general for the lake territory that easily floods is divided into multiple section, if this section exists the grid that the general probability of happening in lake is greater than 50%, then forecast that this generation lake, section waters is general; , namely there is the general area in lake in the grid area sum that in this section, probability is greater than 50%.