Runoff computations for

Runoff computations for water projects

Proceedings of the International Symposium

St. Petersburg (Russia), 30 October -3 November 1995 Parts I and II

Edited by A.V. Rozhdestvensky

IHP-IV Project M-1-4

IHP-V I Technical Documents

Hydrology I ^No.

UNESCO, Paris,

concerning the delimitation of its frontiers or boundaries.

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Defhite progress has been achieved during the last decade

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human

1.

2.

3.

4.

Use of runoff formation

laws

Specific aspects of runoff computations under anthropogenic impact conditions

All the

as

Of

42

in

in Hydrology. Part I

Part II

The organizers

wish

Professor

I.

Chairperson

of

C o n tents

1 Use of

Runoff

A. K

Objective criterion for the selection of analogous river basin for estimation of characteristic discharges in ungauged catchments

A.

Yzi.

World-wide experience of applications of the

HBV

Application of dynamic and stochastic models of water bodies for the forecast purposes V I.: Kovalenko,

A. K

A.

&

D.

A.

Theoretical and methodical aspects of normalizing the design characteristics of maximum flow Ye. D. Gopchenko

Rainfall runoff spatial model

A.

N e w approach for the estimation of extreme roughness in torrents by hydraulic and photogrammetry H.Hode1,

T. P.

&

Laws of formation of a maximum snowmelt flood runoff on small watersheds and ways to improve methods for its computation

B.M.

Calculation of minimum flow in rivers with various streamflow regime types A.M Vladimirov

N e w results of experimental studies on river runoff formation B.

L.

S.

&

K

Global Runoff Data Centre

(GRDC) -

Mean-annual water balance of the Niger River, West Africa t;: Olivera,

D. CMcKinney. Zichuan Ye, D. RMaidment

& S.

Fuzzy set theory as an objective basis for the estimation of the river basins similarity S. Tyszewsky,

A.

&

7 9

17

25

33

45

51

57 65 71

81

85

99

107

115

river basins Oto Mendel

&

On

in

A.M.

Using the water balance subroutine of

CROPWAT

FAO

2 Runoff Computations on the Basis

of

F A . Shelutko

&

Application of models of non-stationary processes for hydrological computations V.

A.

Application of the

VNC

T.

&

Methods for minimum flow computation

I

I

Methods for computation of streamflow dstribution during a year G.A.Plitkrn Indvidual and priori information for runoff computation

A.

S.

&

Application of the

SSAR

Flood

A.

&

L. V. Kokoreva

133

139

147 149

155

165 173

183 189 195

199

207

1 Use of Runoff Formation Laws for Hydrological Computations

PRESENT STATE AND PROSPECTS OF HYDROLOGICAL COMPUTATIONS DEVELOPMENT

Rozhdestvensky,

A.V

State H-vdrologicd Institute. St. Petersbzirg. Russia

The present state of methodologies for hydrological computations in the world practice is mainly reflected in the publications of

UNESCO (UNESCO,

W O (WMO,

1979

(UNESCO,

Updated practice of hydrological computations €or water projects in Russia is based on the use of the official standard document SNzP 2.01.13-83 (Construction standards and regulations) and on the Manual €or determination of design hydrological characteristics (Opredelenie.. ., 1985; Posobie

PO opredeleniu.. ., 1984); these publications contain scientific results and generalized experience for different water projects in Russia and in the

NIS

T h e

likelihood

A

&

A

If

opredeleniu.. ., 1984; Rozhdestvensky, Chebotarev, 1979).

The second category of methods is based on a reduction of short-term hydrometric observations to a long-term period. Moreover, longer observations of river runoff at prototype stations or meteorological runoff factors are used. The maximum effect of these methods is attained by the use of step-by-step reduction with a possible use of several prototypes at each stage (Rekomendatsii PO privedeniu. .., 1979). The developed algorithm makes it possible to recover river runoff in an automatic mode, including a search for most effective prototypes. The specified level

of accuracy and reliability of all the solutions provides a high quality of short-term hydrological series and their parameters reduction to a long-term period.

Finally, the third category of methods is based on the use of regional runoff dependencies upon basic runoff-forming factors. Moreover, space interpolation of runoff characteristics and parameters is widely applied.

On

PCs

W h e n publications (Opredelenie ^..., 1985; Posobie ..., 1984) appeared, fbrther studies aimed at higher accuracy and reliability of hydrological computations were made in the following two directions. Firstly, these were the so-called "tra&tional methods" for hydrological computations which successively reflect an ever-growing level of hydrological science. And, secondly, these were the methods of a 'hew generation" based on the so-called "mathematical modelling" (Vinogradov,

1989).

A

T h e paper describes further research trends in hydrological computations. The maximum scientific effect is usually observed when some additional information on river runoff and on the main factors determining river runoff appears. Therefore, it is reasonable to make firther research to get some additional information, both at an individual project site and in the region of the fbture water project.

Individual hydrometric information at the project site may be obtained by field measurements.

This

A

If one or several good prototypes are available, it is possible to apply the method of ratios, of the specified runoff frequency or year-by-year runoff recovery. It is also possible to plot year-by- year runoff curves showing dependence of runoff for a particular year upon normal runoff or specified frequency runoff, this method m a y be also promising to take the account of short-term observations. In the similar way it is possible to plot runoff curves during the period of short-term observations depending on runoff for other years. These dependencies should be plotted for the stations located

in

T h e

A n expediency of more expensive projects due to field measurements is often douffil.

Therefore, it is reasonable to cite academician B.Paton w h o wrote in his paper "Safety of the progress" (published in "Literatumaya gazeta" No.44 (5 110) dated 29 October 1986):"In fact, when w e begin to relate any project to some particular conditions, say, to a definite location, w e almost always have inadequate data either on its geology, or plants or water balance or anything else. Therefore, the first commandment (to be kept in this case) is not to regret about time and money spent for getting these data. The power concentrated in the hands of a man is so great that it is a crime to launch this power on the off-chance, without thinking about the results. Therefore, w e have to be prepared in advance that a preliminary check of the project would be as expensive (or m a y be even more expensive) than the implementation of the project. Knowledge is costly, but ignorance is much more costly!

This

All

This

Field programmes should be combined with the methods to be used for the account of field measurements.

These investigations are at the initial stage (Rozhdestvensky et al., 1990; Rozhdestvensky, Lobanova, 1991; Rozhdestvensky et al., 1992). W e have to do much not only for a development of new methods for the account of field data for runoff computations, but w e have to check these methods and to estimate the accuracy and reliability of these methods in different regions of the country.

In this situation a question may arise that the so-called methods for runoff computation with inadequate data at the project site are useless, because w e shall always have observation data at the site of the water project. Therefore, it should be noted that these methods embrace some additional information on the main runoff factors and it is hardly reasonable to neglect this information.

The way out of this situation is to use the bayesian approach which is based on the simultaneous account of individual hydrometric information at the project site and regional information too, presented by different empirical runoff dependencies upon different fictors, and by lfferent maps of runoff parameters and characteristics.

It

This

This

if

On

A

At

in

for water projects under the effect of man's activity is a very important problem which should be solved as soon as possible. Here w e have to consider not only a safety and reliability of certain structures but possible results of these structures for water b d e s regimes with particular reference to possible negative ecological consequences produced by different water projects.

Attempts to solve this problem by statistical methods (extrapolation of the trends observed in river runoff) or even by genetic methods in case of inadequate data on the factors of man's impact in dynamics are associated with possible great random errors which make the obtained solution doubtful.

A

'

natural that expert assessments of man's activity can be hardly made for such a long period of time. Therefore, no forecasts of man's activity for a remote future can lead to correct decision- making in the field of engineering and hydrological computations for water projects. Meanwhile, quite realistic prospects of man's activity development for the nearest 5-10 years m a y be taken into account in hydrological computations. Therefore, it is quite possible to formulate a more specific problem, i.e. h o w to take the account of man's activity observed at the moment of water project and to combine it with the plans of the national economy development for the nearest 5-10 years.

In this case any new water project to be constructed during the period of other projects operation should take the account of the effect of new projects on the existing ones, and if necessary, to envisage any reconstruction of these structures, if necessary.

In

If we carefully consider the effect of all kinds of man's activity on dfferent hydrological characteristics, w e m a y conclude, that river runoff would subject to changes for a certain period (unstationary regime), and after this runoff would be stationary again, but its parameters would be new.

In

Therefore, the problem is: what time interval is required for a transitional unstationary runoff regime to be changed from a natural stationary one to a new stationary regime after the effect of a variety of man's activity factors.

A

This

Then, it would be possible to compute year-by-year variability of river runoff during the transitional unstationary period, when there m a y occur changes not only in the mathematical expectation but in year-by-year variations in river runoff. The problem of hydrological computations during that period is to determine conventional distribution curves for the period of water project operation. Moreover, it will be necessary to determine a certain function of probabilities distribution, including hstribution parameters of the new stationary runoff regime.

A

Proceeding from the above, w e m a y outline the following successive procedure in hydrological computations under the effect of man's impact on river runoff.

(1) Assessment of stationarity of long-term river runoff variations by genetic and statistic methods. Ji the later case, it is recommended to use generalized homogeneity criteria for the case of asymmetric and space-time correlated hydrological information (Rekomendatsii PO

statisticheskim metodam.. ., 1979). Nonstationarity dwovered within the limits of hydrometric measurement accuracy (random error of the basic hydrometric information) should not be taken into account for further computations.

During this stage basic hydrometeorological information should be collected in the area of the water project, as well as information on man's activity (present and expected).

(2) Reconstruction of natural runoff disturbed by man's activity, as recommended in (Metdcheskie rekomendatsii ..., 1986; Metodxheslue ukazania ..., 1986; Shiklomanov, 1979).

(3) Assessment of parameters and quantiles of natural streamflow, after their reduction to a long- term period (Rekomendatsii PO privedeniu.. ., 1979).

(4) Reconstruction of natural streamflow, if a variety of factors of man's activity observed by the moment of water project design is transferred to the beginning of hydrometric observations.

Methodological recommendations from (Metodicheskie rekomendatsii.. ., 1986; Metodicheskie ukazania ..., 1986; Shklomanov, 1979, 1988) should be applied. Water balance methods are preferable.

(6) Reconstructioq of the natural streamflow at the recovery of a variety of factors of man's activity for the moment of water project design.

(7) Determination of design hydrological characteristics with the account of the transitional (unstationary) period and a new stationary regime of streamflow, subject to man's impact, related to the moment of water project design. Moreover, computations of mini", annual and seasonal runoff should be determined from the certain frequency curve of the new stationary regime. The design value of maximum runoff should be determined from the conventional frequency curve of the transition period, where the design maximum runoff would be the greatest one. If the design maximum runoff is the greatest at the new stationary regime, the certain frequency curve of the new stationary regime should be taken as the design one.

The effect of possible change in the global climate also associated with the anthropogenic factors (carbon dioxide increase in the atmosphere) on streamflow computations should be based approximately on the same basic principles as runoff computations are based under the conditions of man's impact on the watershed.

As

Most likely, the variant should be selected on the basis of technical and economical computations as well as the account of possible socio-ecological results. Besides, the determination of design runoff values of the certain frequency requires not only the prehction of the dynamics in average variations of meteorological parameters, but a prediction of time variability of these meteorological parameters.

As

And, finally, a co-ordmation of rather general and large-scale models of climate with similar models of runoff formation should be noted, because it is hardly possible to expect a great effect from the use of rather detailed and sophisticated models of runoff formation at the account of global climate change effect on the computation of various hydrological parameters.

A

In

In

;It

if

I

design water discharge obtained from the 50-year series. The accuracy of the design water discharge would be different,

in

In

Therefore, it is proposed to determine the design value of the study hydrological characteristic depending on the category of the structure (which is practised at present) and on the period of the structure operation.

In

the period of the structure operation; as to the level of the confident probability, it should be determined depending on the category of the structure. The confident probabilrty level in fict characterizes the level of the reliability of the design water discharge. This system of standardzation is more flexible, if compared

with

Let

A

For a quantitative solution of this problem it is possible to use the estimate of the sampling quantiles accuracy described in (Rozhdestvensky, 1977), where information on the sampling quantiles parameters is available; on the basis of this information it is possible to compute any confidence limits for any water discharge of the specified frequency.

At

In

in

REFERENCES

Blokhinov,

E.G.

Kritsky, S

.N

M

F

(

Metodicheskie rekomendatsii PO uchetu vliania khoziaistvennoi deiatelnosti na stok malykh rek pri hydrologicheskikh raschetakh dlia vodokhoziaistvennogo proektirovania (1 986).

(Methodological recommendations on the account of man's impact effect on small river runoff for water projects). Leningrad, Gidrometeoizdat, 168 pp.

MetoQcheskie ukazania PO otsenke vliania khoziaistvennoi deiatelnosti na stok srednlkh i bolshlkh rek i vosstanovleniu ego kharakteristlk (1986). (Methodological instructions on the assessment of man's impact effect on mid-size and large river runoff and recovery of runoff characteristics). Leningrad, Gidrometeoizdat, 130 pp.

Mezhdunarodnoe rukovodstvo PO metodam rascheta osnovnykh hydrologicheskikh kharakteristik (1984). (Intemational Guide on the methods for computation of the main hydrological parameters). Leningrad, Gidrometeoizdat, 248 pp.

Opredelenie raschetnykh hydrologicheskikh kharakretistik. (1 985). (Determination of design hydrological characteristics.

SNIP

Posobie PO opredeleniu raschetnykh hydrologicheskkh kharakeristik. (1984). (Manual on determination of design hydrological characteristics). Leningrad, Gidrometeoizdat, 447

PP.

Rekomendatsii PO privedeniu riadov rechnogo stoka i ikh parametrov k mnogoletnemu periodu.

(1979). (Recommendations on the reduction of runoff series and runoff parameters to a long-term period). Leningrad, Gidrometeoizdat, 64 pp .

Rekomendatsii PO statisticheskim metodam analiza odnorodnosti prostranstvenno-vremennykh kolebaniy rechnogo stoka. (1979). (Recommendations on the statistical methods for the analysis of space-time homogeneity of runoff variations). Leningrad, Gidrometeoizdat, 64 PP.

Rozhdestvensky,

A.V.

Rozhdestvensky,

A.V.,

A.I.

Rozhdestvensky,

A.V.,

A.G.

A.V.,

A.V.,

A.V.

Leningrad, Gidrometeoizdat, 276 pp.

Rozhdestvensky,

A.V.,

A.V.,

L.I.

Shiklomanov,

I.A.

Shiklomanov,

I.A.

Leningrad, Gidrometeoizdat, 1 5 3 pp .

UNESCO.

UNESCO

UNESCO.

UNESCO

UNESCO.

UNESCO.

UNESCO

UNESC0.(1989). Evaluation of national guides on methods of hydrological computations.

Technical documents in hydrology,

UNESCO

Vinogradov, Yu.B. (1989). Raschety stoka (Runoff computation. Prospects on the development of new generation methods). Trudy

GGI, On

NO.

W O .

-

CATCHMENTS

Byczkowski,

A., B.

Department of Hydraulic Structures, Warsaw Agricultural Universi& Poland

ABSTRACT

Authors propose an objective criterion for the selection of the analogous basin, so called measure of unit discharges similarity

(k).

1.

INTRODUCTION

During the development of hydrological bases for designs of hydraulic structures, the designers are usually faced with the problem of lack of hydrological data what in consequence, makes the application of the direct (statistical) methods impossible.

Of

2.

THE METHOD OF HYDROLOGICAL ANALOGY

The method of hydrological analogy is applied in calculations of characteristic discharges in the river catchments or cross-sections where only the results of short-term hydrological studies are available, or there is a complete lack of them. W e utilize here information on the discharge in the gauged catchments, being controlled by hydrological survey, in which the processes of the discharge’s formation run in the analogic way as in the considered catchment area. These catchments are called the analogous basins.

In

prolongation of the chronologcal series, and

bringing the parameters of the probability distribution of the investigated characteristic discharge to a longer period, without creating an abstract set of discharge values, obtained as a result of the procedure of sequence prolongation.

Under the situation of complete lack of information on discharges in the investigated river cross-section, the values of the characteristic of discharge, as defined for cross-section analogs are transferred to the investigated cross-section. The transfer m a y be performed by the method of interpolation, of differential river basin, or by the method of extrapolation (Fig. 1).

The interpolation method is applied when on a given river, there are at least two gauge stations with the observations from a longer period of time (Fig.la) and the investigated cross-section is found between them.

The method of differential basin is used in case when the investigated cross-section is found on the ungauged river, having the outlet to the recipient between two gauge stations.

4 investigated profile

Fig.

I.

b) differential basin method; c) extrapolation method.

The method of extrapolation is applied when there is only one profile-analog (Fig.

IC)

Q=kQo- A

A,

where:

Q

Qo -

k A

-

-

-

-

In

Due to complexity of the processes of water circle in the river basin, it is not possible to select two basins with the identical run of these processes

-

smaller similarity of numerical values of specific discharges and their variability.

In the so-far practice, the gauge station, situated at the nearest distance in relation to the river cross-section, closing the given basin, was most frequenty accepted as the analog (Byczkowski, 1989). In case of greater number of potentjal analog, the selection was perfomied on the grounds of subjective evaluation of runoff making factors in the investigated basin and in the basin-analog.

Such w a y of solution of the problem cannot lead to the satisfying results due to the subjective approach to the selection of the analog.

3.

THE MEASURE OF SIMULARITY OF THE SPECIFIC DISCHARGES

In

This

where:

4 -

90 -

The similarity measure

(4

In the studies of the authors, the measure of similarity, k, is calculated from the equation of multi-dimensional regressian, having a form (Byczkowski, 1989; Byczkowski and Mandes, 1986):

where:

XI, X2, . . . , Xk

-

XIo, x20, . . .? Xko

-

a,

-

Similar approach, expressed in determination of adaptation coefficients on the grounds of the quotients of runoff making factors, may be found in the studies, conceming calculations of peak discharges. W e m a y mention here Polish formula of Debski (1956) for calculation of median maximal discharge and that one of Fa1 (1979). The equation, as given in the standard of the former Soviet Union of 1973 for calculation ofthe maximal snowmelt discharge (Rukovodstvo ..., 1973) is based on the siinilar principle.

Physiographical characteristics, appearing in equation (3) are selected from among the elements of the set of potential physiographical characteristics by the quasi-optimization method of Kaczmarek (1 969) or by the stepwise regression of Efreymson, as the most effective values.

Owing to the above ~~ietliod of the approach, the selection of basin-analog, is perfoiined in the objective way.

W i t h

Equation (3) has been differentiated for various discharge characteristics due to the fact that various discharge characteristics are affected by different complexes of runoff making factors.

Precipitation

P

Lake index

J

SELECTED DISCHARGE CHARACTERISTICS.

Precipitation

P

- J

Lakeindex

J

Rwer network

D

N

The authors conducted the studies on the measure of similarity (k) of specific dxharges: the average, median and modal ones (ByczkowskiandMandes, 1986; 1989). The studies were carried out on the territory of north-eastem part of Poland, covering the Narew river basin (without the Bug river catchment) and the basins of the adjoining rivers. The collection of the hydrometrical data, used in the stules, covered the discharges coming from 74 gauge stations during the 35-year period of 1951-1985.

Tne selection of the most effective physiographic characteristics, appearing in equation (3), was performed from among 14 potential precbctors. The set includes: catchment area

(A),

(D),

(Lzl),

(B),

(Z),

(J),

(P).

As

For each investigated basin, one or more anaiogs were selected from the set of potential basins- analogs. W h e n creating this set, the following factors were taken into consideration: the proximity of the location of catcliment area, closed with a considered gauge station and of the analogous basin as well as similarity of the selected runoff m a k m g factors in both basins. For so selected pairs of the basins, the coefficients of correlation of daily discharges, were determined. For further analysis, these basins were accepted as analogs, for which the correlation coefficients of the relationships between the daily discharges and those ones ¹¹¹ the investigated profile, were not smaller than the limitary value (

R

The numerical paraiiieters of the iiiulti-dimeiisioiial regression equation (3) were calculated by the method of compensatory calculus. The formulae for calculations of similarity measure of specific discharges of the considered characteristics, have the following form:

-

1.2

2.42 L+l

RI, = . ) 1 ( . 4 . 9 0 ) PO ( ( ^{LO+l (w) YO}

-

3.43 -0.20

L+l

Po Lo+l Do

3.46

-

5.0 1

4.7s

L+l

Lo+ 1 Po

( 5 )

5.

ANALYSIS OF EQUATIONS

In all developed formulae there are found the factors, the influence of which on the considered discharge characteristics is intuitionally perceptible. The signs of exponents (n) at the particular W h e n comparing the equation for calculations of similarity measure of specific dmharges:

average (Avq), median (Meq) and modal (Moq), it m a y be observed that numerical values of exponents such as: precipitation

(P)

(L),

(L).

(w),

-

0)

(N).

tlre

The effectiveness of the obtained equations was investigated using analysis of relative percentage errors (6) between the values, obtained from the developed formulae and the values, obtauied from hydrometrological data.

~ variables are coiisistent with the physical interpretation of this pheiioiiiai.

The percentage errors were calculated fi-om the relationship:

6; =- xO--x 1 OO(%)

1

x

where:

Xg -

X -

The main values of percentage errors for the investigated random sample were obtained from the formula:

6' = (C/Si/)

n

where:

/Si/ -

n -

Characteristic of discharge Avq

errors in case of average and median dicharges should be considered as being low

(B<

6

[%I

12.0 4

Table 2. The mean values of percentage errors (6') of the equations for the calculation of the measure of specific discharges similarity

M e q M o q

16.4 5

29.5 6

6.

CONCLUSION

The obtained relationships serve for calculation of the similarity measure (k) of specific average, median and modal discharges on the territory of north-eastern part of Poland, depending on the physiographical factors.

The discussed equations create the possibility of objective selection of quasi-optimal analogous basin on the grounds of value analysis of the measure of similarity of specific discharges, calculated for the set of potential basins-analogs:

kept = max {ki)

Measures of similarity of specific discharges with the investigated characterists were affected by the physiographical factors, selected in the objective way, by the quasi-optimization method of Kaczmarek, most strongly affecting intuitionally the studied characteristic of discharge.

The direction of the effect of these factors, expressed by the algebraic signs of exponents, is physically justified.

REFERENCES

Byczkowski, A. (1 979) Hydrologiczne podstawy projektow wodno-melioracyjnych. Przeplywy characterystycne.

PWRiL

Byczkowski,

A.

Nr

189. Melioracje

XXXIV

Byczkowski,

A., B.

Konferencja naukowa z okazji 40-lecia studiow melioracyjnych w

SGGW-AR.

SGGW-AR.

Byczkowski, A., B. Mandes (1 989) Okreslenie miary podobienstwa srednich rocznych odplywow jednostkowych na podstawie charakterystyk zlewni. Zesz. Nauk,

A R

189. Melioracje

XXXIV

Byczkowski,

A., B.

SGGW-

Byczkowski,

A., B.

Meteorol. i Gosp. Wod.

T.XXXVII

Debski,

K

Seria F, T.72, z. 1 (in Polish).

Fal,

B.

bad. IWGW.

Seria

Kacnmrek,

Z.

T.V (WII).

Rukovodstwo PO opredeleiiiju rascetnycli gidrologicesluch cliarakteristik. (1 973) (Guide for determination of design hydrological characteristics). Leningrad, Gidronieteoizdat . (hi

Russian).

RUNOFF COMPUTATION

.B.

State Hydrological Institute. St. Petersburg, Rzissia

FORMULATIQLN OF THE PROBLEM

Hydrological computations, being the basis of engineering hydrology, are tradhonally oriented to the needs of water projects and they were mainly reduced to probabilistic estimates of runoff characteristics.

I

From the user's viewpoint, there is no problem of runoff computation if hydrometric observation data are available. Therefore, it m a y be reasonable to speak about areas where observation data are inadequate or missing. But under the conditions of variable landscapes and climate the alterpative of &rect statistical estimates, which is historically pressing all other approaches, is groundless. Therefore, @e approach discussed in the paper is to a certain extent the single one.

Hydrological computation methods of a new generation which are under development are interrelated withthe possibilities of m o d e m mathematical modelling. But not each model of runoff formation, however, is suitable for this purpose; the majority of models which

I

I

a

During a long. period of time a universal deterministic modelling system "Runoff

-

-

Pollution" was developed and modified at the State Hydrological Institute; the whole system of hydrological computations of the new generation can be based on this system. he proposed methodology is based on the principle of deterministic-stochastic modelling.

I

V-th

1986 (Vinogradov, 1989; Vinogradov et al., 1990).

Using this modelling system, it is possible not only to compute runoff hydrograph but to compute mean daily, loday, monthly, seasonal, annual, maximum and minimum water discharges, suspended sedments and pollutants. Since the modelling m a y be made for any number of years, it is possible to get dstribution curves for all the above discharges, typical of the mode of runoff computation.

In general, different versions and purposes of modelling and some combinations are possible:

1. Two modelling variants depending on the w a y of getting meteorological information at the input of a deterministic model:

1.1. Recomputation of meteorological series into hydrological series with the use of Interpolation Weather Model.

1.2. Simulation modelling with the use of Stochastic Weather Model.

2.1. Past climate conditions.

2.2. Present climate condltions.

2.3. Predicted scenarios of anthropogenic climate change for particular moment in future.

3.1. Landscapes in the historically past time.

3.2. Existing landscapes.

3.3. Predicted anthropogenic landscapes.

2. Three principal variants of climate conditions:

3. Three principal variants of the underlying surface state: