CN105825047A - Pipe network tip water quality simulation method based on GIS - Google Patents

Abstract

The invention discloses a pipe network tip water quality simulation method based on GIS. According to the inflow and outflow relationship between pipe network tip nodes and pipe sections of a community, the characteristics of capacity nodes and the characteristics of capacity-free nodes are combined, a capacity node residual chlorine attenuation model and a capacity-free node residual chlorine attenuation model are respectively built, and known data is substituted into the models, so that capacity node residual chlorine concentration and capacity-free node residual chlorine concentration can be obtained, and further a water quality condition is obtained. Because various parameters generating influence on water quality are added to the residual chlorine attenuation models, a water quality evaluation method which is scientific in algorithm and high in fidelity is formed. The change situation of residual chlorine attenuation of tips of water supply pipe networks can be rapidly and comprehensively understood. The pipe network tip capacity node can be accurately, objectively and scientifically evaluated relatively.

Description

Terminal tap water matter analogy method based on GIS

Technical field

The present invention relates to urban water supply technical field, be specifically related to a kind of Terminal tap water matter analogy method based on GIS.

Background technology

In the water body up to standard course of conveying from water factory to user, owing to water quality is from the impact in factors such as the change of pipe network and outside secondary pollutions, will eventually lead to water supply quality decline in various degree.According to investigations, China's ductwork water quality qualification rate relatively output water declines 0.88 percentage point, wherein turbidity average specific output water height 0.3NTU, and total number of bacteria increases about 4 times. and qualification rate is about 97%, and escherichia coli more only have the qualification rate of about 90%.People are increasingly recognized that the importance that water quality is ensured by drinking water safety transmission & distribution, it may be said that the center of gravity of water quality safeguards technique is the most gradually shifted to pipe network by water factory.

The water analysis of water supply network system consists essentially of two ways, and one is directly sample testing in water supply network, and another kind is to utilize mathematical model of the computer to carry out simulation of water quality.Directly in water supply network, sample testing is typically the concrete application according to pipe network system and about water standard and regulation, selects some water quality parameter to test.This mode, primarily to the purpose of ductwork water quality monitoring, has a wide range of applications field.Although it has irreplaceable effect, but this mode still has price height, is vulnerable to the shortcoming that Practical Project condition limits during actual pipe network monitoring.Owing to city water-supply pipe network has, area is big, branch is many, it is inconsistent to lay the age, the not equal feature of pipe features, it is difficult to the most manually monitoring mode pipeline section each to whole pipe network water quality produces in real time, understands all sidedly.

Summary of the invention

For the deficiencies in the prior art, it is an object of the invention to provide a kind of Terminal tap water matter analogy method based on GIS, in order to accurately, objectively to Terminal tap water matter make scientific evaluation.

To achieve these goals, the present invention adopts the technical scheme that:

Whether the water yield according to flowing into node stays at this node, is divided into by the node of pipe network tip and has appearance node and without holding node；

For there being appearance node, simulate the concentration of chlorine residue according to the following formula

$\frac{\∂\left(V_s{C}_s\right)}{\∂t}={\Σ}_{i\∈Is}{Q}_i{C}_{i/x=L_i}-{\Σ}_{j\∈Os}{Q}_j{C}_s+r\left(C_s\right)$

In formula, s indicates appearance node；

V_sRepresent that t has the actual reservoir volume holding node s；

C_sRepresent that t has and hold the concentration of chlorine residue in node s；

Q_i、L_iRepresenting flow and the length of pipeline section i respectively, pipeline section i is to flow to there is the pipeline section holding node s；

C_{I | x=Li}Represent the x=L of t pipeline section i_iThe residual chlorine concentration at place, is the current starting point of pipeline section i at x=0；

Q_jRepresenting the flow of pipeline section j, pipeline section j is from the pipeline section having appearance node s to flow into after flowing out；

I_s、O_sRepresent inflow respectively, flow out the pipeline section set having appearance node s；

R represents the reactions change function of chlorine residue；

Node is held for nothing, the concentration of employing following formula simulation chlorine residue:

$\left\{\begin{array}{c}\frac{dc}{dt}=-kc\\ k=k_b+\frac{k_f{k}_w}{r_h(k_f+k_w)}\end{array}\right.$

C is the residual chlorine concentration without holding node, and t is that main suit is arrived without holding the time used by node, and k is Residual chlorme decay coefficient, r_hFor pipeline section hydraulic radius, k_bFor water body attenuation quotient, k_fIt is mass tranfer coefficient, k_wIt it is tube wall attenuation quotient.

The present invention is according to the inflow and outflow relation between community pipe network frontier node and pipeline section, and it is combined with appearance node and without holding the feature of node, establish respectively and hold node and without holding the Chlorine Decay model of node, known data are substituted into this model, i.e. can obtain having and hold node and without holding the residual chlorine concentration of node, and then know water quality condition.Owing to Chlorine Decay model adds, water quality is produced the various parameters affected, thus define algorithm science, quality evaluation method that fidelity is higher, the situations of change such as the Chlorine Decay that can understand water supply network tip fast, all sidedly, more accurately, objectively to Terminal tap water matter make scientific evaluation.

Accompanying drawing explanation

Fig. 1 is water calculation process in age schematic diagram；

Fig. 2 is the GIS figure of hillslope processes；

Fig. 3 is tetra-contributing region distribution schematic diagrams of test block A, B, C, D；

Fig. 4 is test block secondary water-supply user terminal node selection schematic diagram；

Fig. 5 is the continuous 48 hours interior water analogue value in age situations of change of certain node；

Fig. 6 is certain node chlorine residue situation of change of the analogue value in continuous 48 hours；

Fig. 7 is pipe network distal point GA cycle water situation of change in age；

Fig. 8 is the situation of change of pipe network distal point GA flow；

Fig. 9 is pipe network distal point GA chlorine residue measured value and the situation of change of the analogue value；

Figure 10 is different monitoring points water situation of change in age on each time point；

Figure 11 is different monitoring points chlorine residue situation of change on each time point.

Detailed description of the invention

The emphasis of this invention is that combining GIS technology carries out dynamic analog to waterpower, the index of correlation of change of water quality in secondary water-supply water distribution system.Valid data according to monitoring point, deduce other water quality condition everywhere in pipe network, and then the water quality condition of whole water supply network system is assessed targetedly, improve the level of Terminal tap water matter management, improve the safety of urban water supply, reliability and economy.

The effective tool that ductwork water quality mathematical model is the most gradually changed with the change of room and time as water quality in prediction water supply network system by approval.Water supply network system water quality model can be divided into two main Types, and one is to pay close attention to affect the chemistry of ductwork water quality, the change of physical characteristic and transformation process, and one is to pay close attention to the control of microorganism in pipe network system.Mathematical model of the computer is utilized can more accurately to obtain the variation of water of pipe network tip to carry out simulation of water quality.

According to the conservation of mass and reaction power theory, under the conditions of certain reaction rate, dissolved matter concentration change in pipeline is an one-dimensional transport reaction equation.At the pipeline section place of intersecting or have at the node that the current beyond pipe network system inject, it is believed that fluid is instantaneous being thoroughly mixed.Whether the water yield according to flowing into node stays at this node, is divided into by the node in pipe network and has appearance node (after current flow into this category node, a period of time to be stored flows out again) and without holding node (water flowing into this node flows out at once).For there being appearance node, such as water tower, pond etc., need to consider the reactions change of dissolved matter in node water capacity, it is assumed that fluid is thoroughly mixed in the regulation structures of pipe network, Chlorine Decay change uses and calculates with drag:

$\frac{\∂\left(V_s{C}_s\right)}{\∂t}={\Σ}_{i\∈Is}{Q}_i{C}_{i/x=L_i}-{\Σ}_{j\∈Os}{Q}_j{C}_s+r\left(C_s\right)$

In formula, s indicates appearance node；

V_sRepresent that t has the actual reservoir volume holding node s；

C_sRepresent that t has and hold the concentration of chlorine residue in node s；

Q_i、L_iRepresenting flow and the length of pipeline section i respectively, pipeline section i is to flow to there is the pipeline section holding node s；

C_{I | x=Li}Represent the x=L of t pipeline section i_iThe residual chlorine concentration at place, is the current starting point of pipeline section i at x=0；

Q_jRepresenting the flow of pipeline section j, pipeline section j is from the pipeline section having appearance node s to flow into after flowing out；

I_s、O_sRepresent inflow respectively, flow out the pipeline section set having appearance node s；

R represents the reactions change function of chlorine residue；

For without holding node, the current of node are from different water sources, and the flow entering this node is the most different, and Chlorine Decay changes over situation and typically calculates by Chlorine Decay first kernel response model.

C is residual chlorine concentration (mg/L) in water body, the time used (second) of t main suit to certain point (node)；K is reaction rate constant, also referred to as total attenuation coefficient, and rh is pipeline section hydraulic radius (m)；Model is first order reaction the decay reaction treatment of chlorine, it is believed that chlorine decay in pipe network can be divided into water body consumption (k_bWater body attenuation quotient, unit is min^-1) and tube wall consumption (k_fBeing mass tranfer coefficient, unit is m/min；k_wBeing tube wall attenuation quotient, unit is m/min) two ingredients.Chlorine Decay constant, different because pipeline material, bore are different, the scope of k is between 10^-3With 10^-5Between, for specific water supply pipe net system, k value should be corrected by water quality testing data.

Chlorine residue is a kind of water quality basic index, and water is not belonging to water quality index, but affects the key factor of water quality index age.It is above Chlorine Decay model, water age computation model is described below.

In water supply network, water age of node is equal to flowing to all current water age of this node with weighted mean that flow is power, and end (i.e. flowing into that one end of this node) water flowing to the arbitrary pipeline section of this node i.e. flows through the time sum used by this pipeline section with current equal to its top water age age, therefore set up model:

MT water source node (level pressure node) is gathered；

The non-aqueous source node of M (transformation node) is gathered

S_jThe all node set that flow to node j adjacent with node j (i.e. make q_ij> 0 all node i)

t_i, t_jNode i, the water age (unit: s) of j

The node that i is adjacent with node j

q_ijPipeline flow (unit: m between node i and j³/s)

L_ijPipeline section pipe range (unit: m) between node i and j

v_ijPipe section flow rate (unit: m/s) between node i and j

Q can be drawn through compensating computation_ij、L_ij、v_ij, simultaneously each pipeline section the flow direction it is also known that in the case of, S can be obtained_j, so time just can utilize known t_iTry to achieve the t of the unknown_j.Because the water age of water source point, the water sequentially obtaining each water unknown node in age was worth t age it is known that then can be substituted into above formula_j.For preventing the same node of iterative solution during calculating, all of node giving an attribute solve, in order to distinguish, water age is known and unknown node, it is stipulated that: if node j water age is known or has solved, then solve_j=1；Otherwise, solve_j=0.Obviously, i.e. have before solving:

${\mathrm{solve}}_j=\left\{\begin{array}{c}1(j\∈MT)\\ 0(j\∈M)\end{array}\right.$

The value of solve is substituted into formula water computation model in age as initial condition, solves.The most only the node meeting following condition is solved: this current age of the node is unknown, and the water of all adjacent nodes of this node of flow direction is known for age.The general first round solves, and is only possible to solve a part of node, and is to start from the node being associated with water source.And carry out second taking turns, third round is when solving, solve the nodes in water outlet age and increase sharply, if general through little traversal number of times, it is possible to travel through all nodes, solve their water value in age.The flow chart calculated (num is non-aqueous source node sum, and k is total traversal number of times) as shown in Figure 1.

Below with a specific embodiment checking Chlorine Decay model and the effect of water computation model in age.

One, test block is chosen

The present invention selects the secondary water-supply facility of certain community and user terminal to be pilot (as shown in Figure 2), this test block water is domestic water, floor space 90000 square metres, construction area 30000 square metres, have 1597 family resident families, with water population 4970 people.Test block has two water inlets, and its water supply network tubing includes ductile iron pipe and steel-plastics composite pipe two kinds.This community aqueous nature is single, and area is moderate, and the data accuracy that monitoring point obtains is higher.Two set water quality on-line monitoring instrument devices are built at A2 the roof in north gate, community entrance and community.

Two, water analysis result in age

Test block has two water inlets, two pump houses, four contributing regions (A, B, C, D district), A, D district is supplied water (water inlet RAD by same pump house, pond S1, S2, water pump group GAD, DAD), B, C district is by another pump house water supply (water inlet RBC, pond S3, S4, water pump group GBC, DBC), wherein 13 layers and following supplied water by low-lift pump, more than 13 layers are supplied water by high-pressure pump, and its network hydraulic operation state is as shown in Figure 3.

Three, water analysis

3.1 chlorine residue sunykatuib analyses

Carrying out water analysis simulation for 1mg/L as initial condition using room temperature 20 DEG C, water source, test block residual chlorine concentration, Fig. 6 shows from the calculating time in test block certain node situation of change of chlorine residue in continuous 48 hours.

The corresponding relation in 3.2 pipe network tip Chlorine Decays and pipe network water age

According to pipe net leakage rate, trial zone being carried out water age and the calculating of flow and analysis, time period chlorine residue each to pipe network tip change is made evaluation and is compared on this basis.If water age of water source point is zero in water supply network model, according to above hypothesis to water reaction rate in age, it is simulated calculating to pipe network distal point water age and flow, obtain the corresponding relation of whole pipe network tip Chlorine Decay and pipe network water age, and choose some representative nodes its analog result is analyzed.

(1) mutation analysis of same node different time points

By (as a example by the A district 13 above user terminal of floor, the situation of change in certain continuous 24 hours water age.As can be seen from Figure 7 this on continuous time point the change in water age in the fluctuation tendency first gone up and then down, water is time maximum occurs in 6 age, main cause is the form that test block uses secondary water-supply, after drinking water stores through pond, water pump pressurizes, by pipeline again for user, be added by two parts time water age of pipe network distal point and obtain, one be tap water flow at water source pond and in pond residence time, two is to rest on pond Zhong Shui to flow to the time of pipe network tip again through pipeline.This two parts time has together decided on the water age of pipe network distal point, and wherein Drinking Water residence time in pond becomes the main factor affecting Terminal tap water age.Owing to water usage at night is greatly decreased, tap water residence time in pond or pipeline increases and the speed of water guide growth in age is accelerated.With daytime water consumption increase, when 9 at current age of the node slightly decline.Along with continuing to increase of afternoon water consumption, 12 up to 24 time during this period of time interior nodes water present obvious falling trend age, and reach the minimum in this continuous time when 21.The water use peak period, along with the increase of user's water consumption, the water velocity in feedwater piping becomes big, the water time of staying in the duct i.e. water that shortens is diminished age, the decay of chlorine residue and corresponding to the reaction of tube wall reduce in water simultaneously so that the residual chlorine concentration of corresponding node increases, and vice versa.Visible, there is corresponding relation with the time of staying of the water consumption of secondary water-supply user terminal and tap water secondary water-supply pond in the variation tendency in water age.

As a example by the interior change in continuous 24 hours of this point (changes in flow rate is shown in Fig. 8, and water change in age is shown in that Fig. 7, chlorine residue change are shown in Fig. 9), sum up the corresponding relation between chlorine residue and water age, flow:

Water age 0 up to 6 time in this time period speedup the fastest, reason is that time period in morning water consumption is that whole day is minimum, Drinking Water time of staying in pond or pipe network increases, and causes water speedup in age to be accelerated, and residual chlorine concentration gradually decreases with the increase in water age within the time period.9 up to 12 time in this period, along with the arrival of water use peak in morning, the water in pipe network is updated, and water speedup in age has declined, and residual chlorine concentration slightly rises.Water consumption 12 up to 19 time in this period in the trend risen after restrain, water consumption has fallen after rise in the afternoon, continue to increase up to 19 time in the afternoon 15 along with water consumption, water slowdown in growth in age, and the chlorine content in this end of term time period (when 19) is higher than the chlorine content of initial (when 12).19 up to 24 time in this period, water consumption is in the high-order stage in one day.This discharge in period of time is in the trend first gone up and then down, and water consumption starts to have fallen after rise from 21 time, this water slight rebound in age；Chlorine content under the influence of the water yield and water age, when 24 at reach new peak value.

(2) mutation analysis of the same time point of different monitoring points

As Figure 10, Figure 11 are shown that the Changing Pattern in the age of chlorine residue and water in monitoring point (9:00) different in certain is continuous 24 hours, 4 monitoring points, (12:00), (19:00), (24:00) respectively.

In terms of the tendency of water curve in age, GA and GD monitoring point water age on each time point is apparently higher than GB, GC point, in Binding experiment district from the point of view of the hydraulic regime of water supply network, the reason producing this situation essentially consists in the actual used water amount actual used water amount less than BC district in AD district, cause drinking water time of staying in pond or pipe network longer, so that the water of this district's pipe network tip is bigger for age.In terms of the trend of chlorine residue curve, when 9 with 12 time, 19 time higher with chlorine residue Similar Broken Line degree when 24, this with the time in 9 up to 12 time, 19 up to 24 time two water use peak sections have indirectly relation.During secondary water-supply, there is certain impact to water age and the chlorine residue of pipe network tip in the water consumption of user terminal.Generally, along with user terminal water consumption increases, the water in pond or pipe network is updated, and Terminal tap water reduces or slowdown in growth age accordingly, and pipe network tip chlorine residue and this water age are inverse ratio, but being increased or decreased of chlorine residue there may be hysteresis effect.When the water velocity of pipeline increases, in pipe network, the water of corresponding node diminishes age, residual chlorine concentration increases.This is because in the water use peak period, the water consumption of each user increases, water velocity in feedwater piping becomes big, the water time of staying in the duct i.e. water that shortens is diminished age, the decay of chlorine residue and corresponding to the reaction of tube wall reduce in water simultaneously, the residual chlorine concentration making corresponding node increases, and vice versa.

Four, modelling verification and precision analysis

4.1 secondary water-supply cistern chlorine residue simulation precision

In the residual chlorine concentration simulation process of pond, it is assumed that the material of storing facilities of water is to be thoroughly mixed, under being thoroughly mixed state, attempted the mixing being current content with any water inlet content by the material in pond.From the point of view of simulation effect, analogue value change curve in time series and measured value keep basically identical, and chlorine residue residual error average is 0.104mg/L (standard deviation is 0.092mg/L, and average standard is mistaken for 0.023), simulates respond well.

The fit solution of chlorine residue dynamic analog is more satisfactory generally, the chlorine residue residual values simulation precision that chlorine residue residual values when 36 and GD (the D district 13 above user terminal of floor) put is the highest, it is respectively-0.024mg/L (standard deviation 0.378mg/L, standard error 0.134mg/L) and 0.009mg/L (standard deviation 0.043mg/L, standard error 0.015mg/L).

To sum up, as a example by uptown secondary water-supply, the change in Terminal tap water age and way of supplying water have indirectly relation.Test block uses the form of secondary water-supply, after drinking water stores through pond, water pump pressurizes, by pipeline again for user, the water of pipe network distal point is obtained by the addition of two parts time age, one be tap water flow at water source pond and in pond residence time, two is to rest on pond Zhong Shui to flow to the time of pipe network tip again through pipeline.This two parts time has together decided on the water age of pipe network distal point, and wherein Drinking Water residence time in pond becomes the main factor affecting Terminal tap water age.Water produces corresponding change with change and the supplementing of the pond water yield of water total amount age, in the change in final body present chlorine residue fluctuation.Generally, residual chlorine concentration is complementary with the variation tendency in water age, and the residual chlorine concentration corresponding to moment that i.e. water age is short is big, and water age, big period then residual chlorine concentration was less.

As seen from the experiment, in the water use peak period, the water consumption of user increases, water velocity in feedwater piping becomes big, the water time of staying in the duct i.e. water that shortens is diminished age, the decay of chlorine residue and corresponding to the reaction of tube wall reduce in water simultaneously so that the residual chlorine concentration of corresponding node increases, and vice versa.Also known that by result of the test, test block water source point, the chlorine residue everywhere of the pipe network distal point free chlorine residual of Terminal tap water in experimental period is more than 0.05mg/L, and the chlorine residue (fluctuating margin is 0.27mg/L-0.59mg/L) of pipe network distal point is superior to national standard requirement.

Additionally, use one-level decaying kinetics model construction Chlorine Decay kinetic model on the basis of test data, from the chlorine residue analogue value with the curve chart of measured value it can be seen that generally the fit solution of chlorine residue dynamic analog more satisfactory, coincide well with reality.

Above-listed detailed description is illustrating for possible embodiments of the present invention, and this embodiment is also not used to limit the scope of the claims of the present invention, and all equivalences done without departing from the present invention are implemented or change, are intended to be limited solely by the scope of the claims of this case.

Claims (3)

1. a Terminal tap water quality detection method based on GIS, it is characterised in that include step:

Whether the water yield according to flowing into node stays at this node, is divided into by the node of pipe network tip and has appearance node and without holding node；

For there being appearance node, simulate the concentration of chlorine residue according to the following formula

$\frac{\∂\left(V_s{C}_s\right)}{\∂t}={\mathrm{\Σ}}_{i\∈Is}{Q}_i{C}_{i/x=L_i}-{\mathrm{\Σ}}_{j\∈Os}{Q}_j{C}_s+r\left(C_s\right)$

In formula, s indicates appearance node；

V_sRepresent that t has the actual reservoir volume holding node s；

C_sRepresent that t has and hold the concentration of chlorine residue in node s；

Q_i、L_iRepresenting flow and the length of pipeline section i respectively, pipeline section i is to flow to there is the pipeline section holding node s；

C_{I | x=Li}Represent the x=L of t pipeline section i_iThe residual chlorine concentration at place, is the current starting point of pipeline section i at x=0；

Q_jRepresenting the flow of pipeline section j, pipeline section j is from the pipeline section having appearance node s to flow into after flowing out；

I_s、O_sRepresent inflow respectively, flow out the pipeline section set having appearance node s；

R represents the reactions change function of chlorine residue；

Node is held for nothing, the concentration of employing following formula simulation chlorine residue:

$\left\{\begin{array}{c}\frac{dc}{dt}=-kc\\ k=k_b+\frac{k_f{k}_w}{r_h(k_f+k_w)}\end{array}\right.$

C is the residual chlorine concentration without holding node, and t is that main suit is arrived without holding the time used by node, and k is Residual chlorme decay coefficient, r_hFor pipeline section hydraulic radius, k_bFor water body attenuation quotient, k_fIt is mass tranfer coefficient, k_wIt it is tube wall attenuation quotient.

Terminal tap water quality detection method based on GIS the most according to claim 1, it is characterised in that

Further comprise the steps of: according to the following formula calculate pipe network frontier node water age:

$t_j=\left\{\begin{array}{c}0,(j\∈MT)\\ \frac{\underset{i\∈S_j}{\Σ}{q}_{ij}(t_i+\frac{L_{ij}}{v_{ij}})}{\underset{i\∈S_j}{\Σ}{q}_{ij}},(j\∈M)\end{array}\right.$

MT represents the set of water source node, and M represents the set of non-aqueous source node, and i represents the node adjacent with node j, S_jRepresent all node set that flow to node j adjacent with node j, t_i, t_jRepresent the water age of node i, j, q respectively_ijRepresent the pipeline flow between node i and j, L_ijRepresent the pipeline section pipe range between node i and j, v_ijRepresent the pipe section flow rate between node i and j；

Q can be obtained by compensating computation_ij、L_ij、v_ij。

Terminal tap water quality detection method based on GIS the most according to claim 2, it is characterised in that

During solving pipe network frontier node water age, start to calculate water age from the node being associated with water source node, only the most unknown for age to water, and node known to water age of all adjacent nodes of this node of flow direction carries out water calculating in age.