adaptation hydrological model_en

IPA CBC Programme Bulgaria - Serbia

EUROPEAN UNION Bulgaria – Serbia IPA Cross-border Programme

“Assessment of flood risk – a base for sustainable development in upper part of Nishava catchment”

ADAPTATION OF HYDROLOGICAL MODEL FOR NISHAVA RIVER BASIN

The determination of the maximum run-off with different security is a key task in flood

risk assessment. The availability of reliable and spatially distributed parameters of

extreme maximum run-off is essential for adequate flood risk management. In flood

risk mapping and planning of mitigation measures, it is crutial to calculate the

repetition period correctly.

Implementation of the regionalization method of maximum run-off for Nishava

River Basin

Theoretical approach

Eight factors and characteristics of drainage basins and river systems that are

essential for the formation of maximum flow are set out in LUBW, 2007:

• area of the catchment AEo [km2]

• urbanized territory S [%]

• afforestation W [%]

• average slope Ig [%]

• river length L [km] along the main rivers of the watershed to the confluence

• river length LC [km] from the center of gravity of the catchment to its estuary;

• average annual rainfall in the catchment hNG [mm]

• landscape factor LF [-]

The described characteristics and factors are included in multiple linear regression

equation, which equation is used to determine the maximum run-off with a different

security (ie, MHQ and HQT), especially for the unobserved catchment:




where: Y, YT are dependent variables

MHqY regionalization of the values of average maximum water levels / MHQ /;

MHq

HqY T

T : T = 2, ..., 10 000 a - for the regionalization of the values of maximum

discharges HQT;

MHq: module outflow average maximum annual flow MHQ (m³ / s/km2)

HqT: module flow of maximum annual flow to a particular security or repetition period

(T) - HQT (m³ / s/km2)

C0 - C8: regression coefficients.

Used information

For the implementation of the method of regionalization (HQT-model), information

about the maximum run-off from 6 HMS located in the upper catchment of the river

Nisav was used. Information about the HMS and the observation period and their

catchment area is presented in Table. 1 and the spatial location of the HMS is

presented in Figure 1.

Table 1. HMS and observation period

Subbasin HMS-Nr. Observations Number Area

Name From/to years km²

Visochica River (HMS Brachevci – R. Serbia) 47937 1961 - 2010 49 227.00

LFChNC

LCLC

ICWC

SCACCY

G

C

g

Eo

lnln

lnln

ln1ln

1lnlnln

87

65

43

210




Erma river (HMS Strezimirovtsi – R. Bulgaria) 452 1961-1967 7 117,00

Erma River (HMS Trunski Odorovtsi – R.

Serbia) 47914 1961-2010 49 557.00

Erma River ( HMS Trun – Bulgaria) 11650/95 1937-1983 37 360,5

Nishava River (HMS Dimitrovgrad – R. Serbia) 47910 1961-2010 49 232.00

Nishava river (HMS Kalotina – R. Bulgaria) 11800/223 1967-1983 16 267,00

Fig. 1 Gauging stations in the basin of Nishava river

The estimated empirical probability curves of maximum run-off are presented in

Fig.2.

Figure 2 Empirical probability curves of maximum run-off




0

20

40

60

80

100

120

0 20 40 60 80 100 120

Empirical distribution curve of Nishava river, HMS Dimitrovgrad

m3/s

p%

0

20

40

60

80

100

120

140

160

180

0 10 20 30 40 50 60 70 80 90 100

Empirical security curve of Nishava river, HMS Trnski Odorovtsi m3/s

p%




The statistical parameters that define the curve of security log-Pearson Type III are

presented in Table. 2.

Table 2. Statistical parameters of the curve log-Pearson Type III.

Statistical

parameters

HMS

Dimitrovgrad

HMS

Trnski

Odorovtsi

HMS

Brachevtsi

X 1,4334 1,5569 1,5237

S 0,3212 0,2913 0,2749

G 0,1 0,2 0,1

Based on this, the annual probability of exceedance is determined and persented in

table 3

Table 3. Maximum run-off with different security of Nishava river

Annual probability

HMS Dimitrovgrad,

Q

HMS Trnski odorovtsi,

Q m3/s

HMS Brachevtsi,

Q m3/s

Repetition interval

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

Empirical distribution curve of Visochica river, HMS Brachevtsi

m3/s




m3/s

1,0 2.0229 3.94 3.6276 Each year

0,5 26.7285 35.25 33.0469 Every two years

0,2 Every five years

0,1 70.428 86.28 75.6502 Every ten years

0,02 129.1611 153.43 126.7377 Every fifty years

0,01 160.0589 189.26 152.5291 Every hundred

years

0,002 247.6213 292.58 223.0177 Every five hundred

years

The theoretical distribution functions which best approximate the empirical

security curves of the studied HMS and the statistical parameters that define them

are shown in Fig. 3

Figure 3. Theoretical distribution curve Nišava River HMS Dimitrovgrad




Theoretical distribution function of Nishava river, HMS Trnski Odorovtsi

Theoretical distribution function of Visochitsa river, HMS Brachevtsi

0

50

100

150

200

250

300

0 20 40 60 80 100 120

Имперична крива

Теоретична крива

m3/s

p%

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120






Определяне на ландшафтните фактори

Figure 4. Main geological types in Nishava river basin

Figure 5. Main geological types

0

50

100

150

200

250

0 20 40 60 80 100 120






Figure 6 Landuse map, Corine 2006

Determination of the maximum run-off by the regiuonalization method




the values of water quantity (HQT), determined by the method of regionalization and

the empirical values of the maximum run-off /Plotting Positions/ are shown in Fig.7.

These graphics show that authoritative (relevant) HMS model adapted to the

regionalization can well estimate the values of water quantity.Fig.7.

Figure 7. Maximum run-off with different security of Nishava river determined by the

method of regionalization, HMS Dimitrovgrad

Figure 8. Maximum runoff with different security of Erma river set by the method of

regionalization, HMS Trnski Odorovtsi

0

50

100

150

200

250

300

0 20 40 60 80 100 120



Регионализирана крива

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120




p%

m3/s




Figure 9. Maximum runoff with different security of Visochitsa river set by the method

of regionalization, HMS Brachevtsi

Determination of the maximum run-off with different security of Nishava river

by the method of regionalization

Through regionalization (adapted to regional run-off values with a certain probability)

it is possible to easily and quickly determine the water levels with a certain probability

anywhere on the river area for future research in this area.

The values of the parameters and the factors of maximum run-off in Nishava river in

Godech are presented in Table.4

Table 4. Parameter values and factors of the Nišava river in Godech town

River - HMS

HMS-

№

Peri

od

Leng

ht .

AE

0 AE0 U W IG L LC

NJa

hr

LF

(Gemittelt

)

LF

(Zielwert)

GI

S km2 % % % km km

m

m

Nishava –

83, 1,1 6 1, 26, 6,7 96

135

0

50

100

150

200

250

0 10 20 30 40 50 60 70 80 90 100 110




m3/s




Godech town 05 5 4 3 32 5 0

The values of the maximum run-off with different interval times, calculated by the

regionalization method are presented in Table.5

Table 5. Maximum run-off with different interval times, calculated by the

regionalization method

ln(Y) Y=MHq MHQ YT HqT HQT

[m3/s/km2] [m3/s] [m3/s/km2] [m3/s]

MHq -0.652608 0.520686 43.243

Hq2 50 -0.211010 0.8097661 0.422 35.017

Hq5 20 0.332801 1.3948698 0.726 60.318

Hq10 10 0.620712 1.8602528 0.969 80.443

Hq20 5 0.862025 2.3679504 1.233 102.397

Hq50 2 1.135126 3.1115644 1.620 134.553

Hq100 1 1.318140 3.7364666 1.946 161.576

Hq200 0,5 1.487383 4.4254975 2.304 191.372

Hq500 0,2 1.693249 5.4371176 2.831 235.117

Studies show that the regionalization method developed in Germany is applicable

both for Bulgaria and the Republic of Serbia and provides very good results. By this

method it was possible to reliably determining the maximum water levels in the river

Nishava Godech.

This publication was elaboraed with the assistance of the European Union, through IPA Cross-border co-operation programme CCI No 2007CB16IPO006.

The contents of this publication is a responsibility of the SRD-SU „St. Kliment Ohridski” and should in no way be accepted as a statement of the European Union or the Managaing

Authority of the programme.

adaptation hydrological model_en

Technology

nishava river hms dimitrovgrad

nishava catchment

nishava river hms kalotina

erma river hms trun

studied hms

upper catchment

river systems

hms brachevtsi m3s