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1.
Andrzej Karbowski 《Water Resources Management》1993,7(3):207-223
This article presents the formal analysis of a problem of the optimal flood control in systems of serially connected multiple water reservoirs. It is assumed, that the basic goal is minimization of the peak flow measured at a point (cross-section) located downstream from all reservoirs and that inflows to the system are deterministic. A theorem expressing sufficient conditions of optimality for combinations of releases from the reservoirs is presented together with the relevant proof. The main features of the optimal combinations of controls are thoroughly explained. Afterwards, two methods of determining the optimal releases are presented. Finally, the results of the application of the proposed methodology to a small, four reservoir system are presented.Notations
c
i
contribution of theith,i=1, ...,m, reservoir to the total storage capacity of the multireservoir system
-
d
i
(t)
one of the uncontrolled inflows to the cascade at timet (fori=1 main inflow to the cascade, fori=2, ...,m, side inflow to theith reservoir, fori=m+1 side inflow at pointP)
-
total inflow to theith reservoir,i=2, ...,m, at timet (i.e., inflowd
i
augmented with properly delayed releaser
i–1 from the previous reservoir) (used only in figures)
-
d(t),d
S
(t)
(the first term is used in text, the second one in figures) aggregated inflow to the cascade (natural flow at pointP) at timet
-
time derivative of the aggregated inflow at timet
-
i
reservoir index
-
m
number of reservoirs in cascade
-
P
control point, flood damage center
-
minimal peak of the flow at pointP (cutting level)
-
Q
p
(t)
flow measured at pointP at timet
-
flow measured at pointP at timet, corresponding to the optimal control of the cascade
-
r
i
(t)
release from theith reservoir at timet, i=1, ...,m
-
optimal release from theith reservoir at timet, i=1, ...,m
-
r
1
*
(t)
a certain release from theith reservoir at timet, different than
,i=1, ...,m, (used only in the proof of Theorem 1)
-
a piece of the optimal release from themth reservoir outside period
at timet
-
assumed storage of theith reservoir at time
(used only in the proof of Theorem 1)
-
s
i
(t)
storage of theith reservoir at timet, i=1, ...,m
-
time derivative of the storage of theith reservoir at timet, i=1, ...,m
-
storage capacity of theith reservoir,i=1, ...,m
-
(the first term is used in text, the second one in figures) total storage capacity of the cascade of reservoirs
-
S*
sum of storages, caused by implementingr
i
*
,i=1, ...,m, of all reservoirs measured at
(used only in the proof of Theorem 1)
-
t
time variable (continuous)
-
t
0
initial time of the control horizon
-
t
a
initial time of the period of constant flow equal
at pointP
-
initial time of the period of the essential filling of theith reservoir,i=1, ...,m (used only in the proof of Theorem 1)
-
t
b
final time of the period of constant flow equal
at pointP
-
final time of the period of the essential filling of theith reservoir,i=1, ...,m (used only in the proof of Theorem 1)
-
time of filling up of theith reservoir while applying method with switching of the active reservoir
-
t
f
final time of the control horizon
-
fori=1, ...,m–1, time lag betweenith andi+1th reservoir; fori=m time lag between the lowest reservoir of the cascade and the control pointP 相似文献
2.
This paper, the first of two, develops a real-time flood forecasting model using Burg's maximum-entropy spectral analysis (MESA). Fundamental to MESA is the extension of autocovariance and cross-covariance matrices describing the correlations within and between rainfall and runoff series. These matrices are used to derive the model forecasting equations (with and without feedback). The model may be potentially applicable to any pair of correlated hydrologic processes.Notation
a
k
extension coefficient of the model atkth step
-
B
k
backward extension matrix forkth step
-
B
ijk
element of the matrixB
k
(i,j=1, 2)
-
c
k
coefficient of the entropy model atkth step in the LB algorithm
- e
k
(e
x
,e
y
)k = forecast error vector atkth step
-
E
k
error matrix atkth step
-
E
ijk
element of theE
k
(i,j=1, 2)
-
f
frequency
-
F
k
forward extension matrix atkth step
-
F
ijk
element of theF
k
matrix (i,j=1, 2)
-
H(f)
entropy expressed in terms of frequency
-
H
X
entropy of the rainfall process (X)
-
H
Y
entropy of the runoff process (Y)
-
H
XY
entropy of the rainfall-runoff process
-
I
identity matrix
-
forecast lead time
-
m
model order, number of autocorrelations
-
R
correlation matrix
-
S
x
standard deviation of the rainfall data
-
S
y
standard deviation of the runoff data
-
t
time
-
T
1
rainfall record
-
T
2
runoff record
-
T
rainfall-runoff record (T=T
1
T
2)
-
x
t
rainfall data (depth)
-
X
X() = rainfall process
-
mean of the rainfall data
-
y
t
direct runoff data (discharge)
-
Y
Y() = runoff process
-
mean of the runoff data
- (x, y)
t
rainfall-runoff data (att T)
- (x, y, z)
t
rainfall-runoff-sediment yield data (att T)
-
z
complex number (in spectral analysis)
-
k
coefficient of the LB algorithm atkth step
-
nj
Lagrange multiplier atjth location in the
n
matrix
-
n
n
= matrix of the Lagrange multiplier atkth step
-
X
(k),
Y
(k)
autocorrelation function of rainfall and runoff processes atkth lag
-
XY
(k)
cross-correlation function of rainfall and runoff processes atkth lag
-
W
1(f)
power spectrum of rainfall or runoff
-
W
2(f)
cross-spectrum of rainfall or runoff
Abbreviations acf
autocorrelation function
- ARMA
autoregressive moving average (model)
- ARMAX
ARMA with exogenous input
- ccf
cross-correlation function
- det()
determinant of the (...) matrix
- E[...]
expectation of [...]
- FLT
forecast lead time
- KF
Kalman filter
- LB
Levinson-Burg (algorithm)
- MESA
maximum entropy spectral analysis
- MSE
mean square error
- SS
state-space (model)
- STI
sampling time interval
-
forecast ofx
-
forecast ofx -step ahead
-
x
F
feedback ofx-value (real value)
- |x|
module (absolute value) ofx
-
X
–1
inverse of the matrixX
-
X*
transpose of the matrixX 相似文献
3.
Proper well management requires the determination of characteristic hydraulic parameters of production wells such as well loss coefficient (C) and aquifer loss coefficient (B), which are conventionally determined by the graphical analysis ofstep-drawdowntest data. However, in the present study, the efficacy of a non-conventional optimization technique called Genetic Algorithm (GA), which ensures near-optimal or optimal solutions, is assessedin determining well parameters from step-drawdown test data. Computer programs were developed to optimize the well parametersby GA technique for two cases: (i) optimization of B and C only, and (ii) optimization of B, C and p (exponent) as well as to evaluate the well condition. The reliability and robustness of the developed computer programs were tested usingnine sets of published and unpublished step-drawdown data from varying hydrogeologic conditions. The well parameters obtained by the GA technique were compared with those obtained by the conventional graphical method in terms of root mean square error(RMSE) and visual inspection. It was revealed that the GA technique yielded more reliable well parameters with significantlylow values of RMSE for almost all the datasets, especially in caseof three-variable optimization. The optimal values of the parametersB, C and p for the nine datasets were found to range from 0.382 to 2.292 min m-2, 0.091 to 3.262, and 1.8 to 3.6, respectively. Because of a wide variation of p, the GA techniqueresulted in considerably different but dependable and robust well parameters as well as well specific capacity and well efficiency compared to the graphical method. The condition of three wells was found to be good, one well bad and that of the remaining five wells satisfactory. The performance evaluation of the developed GA code indicated that a proper selection of generation number and population size is essential to ensure efficient optimization. Furthermore,a sensitivity analysis of the obtained optimal parameters demonstrated that the GA technique resulted in a unique set ofthe parameters for all the nine datasets. It is concluded thatthe GA technique is an effective and reliable numerical tool for determining the characteristic hydraulic parameters of production wells. 相似文献
4.
The nonlinear Boussinesq equation is used to understand water table fluctuations in various ditch drainage problems. An approximate solution of this equation with a random initial condition and deterministic boundary conditions, recharge rate and aquifer parameters has been developed to predict a transient water table in a ditch-drainage system. The effects of uncertainty in the initial condition on the water table are illustrated with the help of a synthetic example. These results would find applications in ditch-drainage design.Notation
A
/ tanh t
-
a
lower value of the random variable representing the initial water table height at the mid point
-
a+b
Upper value of the random variable representing the initial water table height at the midpoint
-
B
tanh t
-
C
4/
-
h
variable water table height
- h
mean of the variable water table height
-
h
m
variable water table height at the mid point
- h
m
mean of the variable water table height at the mid point
-
K
hydraulic conductivity
-
L
half spacing between the ditches
-
m
0
initial water table height at the mid point
-
N
Uniform rate of recharge
-
S
specific yield
-
t
time of observation
-
x
distance measured from the ditch boundary
-
(4/SL)(NK)1/2
-
(L/4)(N/K)1/2
-
dummy integral variable 相似文献
5.
Soil-water distribution in homogeneous soil profiles of Yolo clay loam and Yolo sand (Typic xerorthents) irrigated from a circular source of water, was measured several times after the initiation of irrigation. The effect of trickle discharge rates and soil type on the locations of the wetting front and soil-water distribution was considered. Soil-water tension and hydraulic conductivity, as functions of soil-water content, were also measured. The theories of time-dependent, linearized infiltration from a circular source and a finite-element solution of the two-dimensional transient soil-water equation were compared with the experimental results. In general, for both soils the computer horizontal and vertical advances of the wetting front were closely related to those observed. With both theories, a better prediction of the wetting front position for the clay loam soil than for the sandy soil is shown. The calculated and measured horizontal vertical advances did not agree over long periods of time. With the linearized solution, overestimated and underestimated vertical advances for the clay and sandy soils, respectively, were shown. The finite-element model approximate in a better way the vertical advances than the linearized solution, while an opposite tendency for the horizontal advances indicated, especially in sandy soil.Notation
k
constant (dK/d)
-
K
hydraulic conductivity
-
K
0
saturated hydraulic conductivity
-
J
0,J
1
Bessel functions of the first kind
-
h
soil water tension
-
q
Q/r
0
2
-
Q
discharge rate
-
r
cylindrical coordinate; also horizontal distance in soil surface
-
R
dimensionless quantity forr
-
r
0
constant pond radius
-
R
0
dimensionless quantity forr
0
-
t
time
-
T
dimensionless quantity fort
-
x, y
Cartesian coordinates
-
z
vertical coordinate; also vertical distance along thez axis chosen positively downward
-
Z
dimensionless quantity forz
-
empirical soil characteristic constant
-
dummy variable of integration
-
volumetric soil water content
-
matrix flux potential
-
dimensionless quantity for 相似文献
6.
The irrigation in regions of brackish groundwater in many parts of the world results in the rise of the water-table very close to the groundsurface. The salinity of the productive soils is therefore increased. A proper layout of the ditch-drainage system and the prediction of the spatio-temporal variation of the water table under such conditions are of crucial importance in order to control the undesirable growth of the water-table. In this paper, an approximate solution of the nonlinear Boussinesq equation has been derived to describe the water-table variations in a ditch-drainage system with a random initial condition and transient recharge. The applications of the solution is discussed with the help of a synthetic example.Notations
a
lower value of the random variable representing the initial water-table height at the groundwater divide
-
a+b
upper value of the random variable representing the initial water-table height at the groundwater divide
-
h
variable water-table height measured from the base of the aquifer
-
K
hydraulic conductivity
-
L
half width between ditches
-
m
0
initial water-table height at the groundwater divide
-
N(t)
rate of transient recharge at time t
-
N
0
initial rate of transient recharge
-
P
N
0/K
-
S
Specific yield
-
t
time of observation
-
t
0
logarithmic decrement of the recharge function
-
T
Kt/SL
-
x
distance measured from the ditch boundary
-
X
x/L
-
Y
h/L
- Y
mean of Y
- Y
Variance of Y 相似文献
7.
A unit hydrograph (UH) obtained from past storms can be used to predict a direct runoff hydrograph (DRH) based on the effective rainfall hyetograph (ERH) of a new storm. The objective functions in commonly used linear programming (LP) formulations for obtaining an optimal UH are (1) minimizing the sum of absolute deviations (MSAD) and (2) minimizing the largest absolute deviation (MLAD). This paper proposes two alternative LP formulations for obtaining an optimal UH, namely, (1) minimizing the weighted sum of absolute deviations (MWSAD) and (2) minimizing the range of deviations (MRNG). In this paper the predicted DRHs as well as the regenerated DRHs by using the UHs obtained from different LP formulations were compared using a statistical cross-validation technique. The golden section search method was used to determine the optimal weights for the model of MWSAD. The numerical results show that the UH by MRNG is better than that by MLAD in regenerating and predicting DRHs. It is also found that the model MWSAD with a properly selected weighing function would produce a UH that is better in predicting the DRHs than the commonly used MSAD.Notations
M
number of effective rainfall increments
-
N
number of direct runoff hydrograph ordinates
-
R
number of storms
- MSAD
minimize sum of absolute deviation
- MWSAD
minimize weighted sum of absolute deviation
- MLAD
minimize the largest absolute deviation
- MRNG
minimize the range of deviation
- RMSE
root mean square error
-
P
m
effective rainfall in time interval [(m–1)t,mt]
-
Q
n
direct runoff at discrete timent
-
U
k
unit hydrograph ordinate at discrete timekt
-
W
n
weight assigned to error associated with estimatingQ
n
-
n
+
error associated with over-estimation ofQ
n
-
n
–
error associated with under-estimation ofQ
n
-
max
+
maximum positive error in fitting direct runoff hydrograph
-
max
–
maximum negative error in fitting direct runoff hydrograph
-
max
largest absolute error in fitting obtained direct runoff
-
E
r,1
thelth error criterion measuring the fit between the observed DRHs and the predicted (or reproduced) DRHs for therth storm
-
E
1
averaged value of error criterion overR storms 相似文献
8.
Omar Ali Al-Khashman 《Water Resources Management》2009,23(6):1041-1053
The present study investigates the chemical composition of Ma’an Wastewater Treatment Plant in south Jordan. Samples of effluent
of this plant were collected over 1 year period. All samples were analyzed for pH, conductivity, major ions (Cl − , , , , , Na + , K + , Ca2 + and Mg2 + ) and trace metals B, Fe, Cu, Zn, Cd and Pb. The pH value ranges from 6.79 to 8.15 with a median value of 7.39 ± 0.32. The
water quality was characterized by its high salinity hazard (C3) and low sodium hazard (S1) which can be considered as marginal
for human consumption. Moreover, concentrations of trace metals in treated wastewater were found to be low and within guidelines
for irrigation water due to low level of industrialization activities in the study area. Generally, the result of this study
suggests that the treated wastewater is suitable for irrigational purposes, while these effluents can be considered as possible
additional resources for irrigation in Jordan. 相似文献
9.
V. I. Istomin 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1989,23(12):689-693
The use of the main methods of calculating Kc in practice guarantees an accuracy of the calculation within
相似文献
10.
Using a large set of rainfall-runoff data from 234 small to large watersheds from USA, this paper evaluates the modified version of the [Mishra, S. K. and Singh, V. P., 2002a, SCS-CN-based hydrologic simulation package, in V. P. Singh and D. K. Frevert (eds), Mathematical Models in Small Watershed Hydrology, Water Resources Publications, Chap. 13, pp. 391–464] (MS) model which is based on the Soil Conservation Service Curve Number (SCS-CN) methodology and incorporates the antecedent moisture in direct surface runoff computations. Comparison with the existing SCS-CN method using the t-test and the ranking-based grading shows that the modified MS model performs far better than the existing SCS-CN model. 相似文献
11.
kerkides p. poulovassilis a. argyrokastritis i. elmaloglou s. 《Water Resources Management》1997,11(5):323-338
The problem of vertical one-dimensional infiltration for both ponded and constant flux boundary conditions was studied through the use of existing analytic solutions. Main objective was to compare the soil moisture profile developed under constant flux boundary condition at the time of ponding
, with that moisture profile developed under ponded conditions at an earlier time
. Time t
C denotes the time when the decreasing infiltration rate for the ponded conditions becomes equal to the constant flux
q
, applied for the constant flux case. One might state that the analytical solutions, for both cases do not give identical profiles. An approximate coincidence might be brought about through a modification in the diffusivity which, in many respects, seems justified. Practical outcome of the above analysis is the determination of the time of ponding T, after which surface runoff starts, for the constant flux case. This is of practical significance either under natural conditions of rainfall or under conditions of sprinkle-irrigation, since surface runoff is directly related with soil erosion and waste of irrigation water. Therefore any attempt to determine the time of ponding T is well merited. 相似文献
12.
Forecast model of water consumption for Naples 总被引:1,自引:1,他引:0
The data refer to the monthly water consumption in the Neapolitan area over more than a 30 year period. The model proposed makes it possible to separate the trend in the water consumption time series from the seasonal fluctuation characterized by monthly peak coefficients with residual component. An ARMA (1,1) model has been used to fit the residual component process. Furthermore, the availability of daily water consumption data for a three-year period allows the calculation of the daily peak coefficients for each month, and makes it possible to determine future water demand on the day of peak water consumption.Notation
j
numerical order of the month in the year
-
i
numerical order of the year in the time series
-
t
numerical order of the month in the time series
-
h
numerical order of the month in the sequence of measured and predicted consumption values after the final stage t of the observation period
-
Z
ji
effective monthly water consumption in the month j in the year i (expressed as m3/day)
-
T
ji
predicted monthly water consumption in the month j in the year i minus the seasonal and stochastic component (expressed as m3/day)
-
C
ji
monthly peak coefficient
-
E
ji
stochastic component of the monthly water consumption in the month of j in the year i
-
Z
i
water consumption in the year i (expressed as m3/year)
-
Z
j
(t)
water consumption in the month j during the observation period (expressed as m3/day)
-
evaluation of the correlation coefficient
-
Z
j
(t)
water consumption in the month j during the observation period minus the trend
-
Y
t
transformed stochastic component from E
t
: Y
t
=ln Et
-
Y
t+h
measured value of stochastic component for t+h period after the final stage t of the observation period
-
Y
t
(h)
predicted value of stochastic component for t+h period after the final stage t of the observation period
- j
transformation coefficients from the ARMA process (m, n) to the MA () process 相似文献
13.
A method capable of estimating the hydrograph from a prescribed storm for a practical mild slope upstream catchment is proposed. This method makes use of two new characteristic parameters, andS, in conjunction with the kinematic wave equation to compute lateral inflows of the main stream of the catchment. The depth profile of overland flow at any instant within the catchment and hydrograph at any location can be easily found. Lag times for individual lateral inflows are then considered and are linearly combined to obtain the hydrograph at the outlet of the catchment or depth profile of the main stream at any instant. The validity of the excess rainfall-surface runoff linear relationship in this study has also been verified with Tatsunokuchiyama catchment, and it shows good results for this computed runoff. 相似文献
14.
V. I. Veselov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1982,16(5):267-273
Conclusions An experimental check of various low specific-speed pumps showed that on changing the geometry of the vaning of the impeller, in conformity with the recommendations [1], the main feature of which is an increase of the outlet angles of the vanes to values 90°2130° and installation of short intermediate vanes in the passages between the main vanes, the head increases considerably without a decrease of pump efficiency.For centrifugal pumps with a volute and diffuser whose impellers have a different number of main vanes, the most rational is the installation of three intermediate vanes in each vane passage with a change in the direction of the flow by the main vane toward an increase of the outlet angle on diameter D2=0.5–0.65D3 for fecal pumps and pumps with short vanes.The use of the new impeller design is especially effective for high rotative-speed pumps. For multistage submersible pumps with a guide-vane apparatus at the inlet and axial outlet, the optimal variant is the installation of one intermediate vane with a start of the change in the flow direction D3=0.63D2.In conclusion, it is necessary to note that all tests were conducted without modifying the casing and branch pipes, which leaves room for a further increase of the head developed by pumps with the new type of impeller.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 21–25, May, 1982. 相似文献
15.
K. P. Meskheli 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1990,24(12):747-755
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