1. Програма за ТГС по ИПП
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FLOOD RISK IN NISHAVA RIVER BASIN
Nishava river basin is a transboundary river basin, located in the Republic of
Bulgaria and Serbia with an area 4113 km 2 /26.9% of this area is located within the
Republic of Bulgaria/.
Nišava river is a right tributary and also the longest and deepest one of South
Morava (Bulgarian Morava) River. The river 248 km long, of which 40 km are on
Bulgarian territory and 208 km on Serbian territory. Nišava river rises east of the
peak Kom in Stara Planina. In its upper course it is called Ginska river so often
(mainly in Serbia) is believed that Nishava originated after a merger with Ginska
River on Serbian territory, near the village Sukova. Before the village of Gintsi
Nishava flows in a deep valley, and then passes through Godech Valley. After
Razboishte village and before the village of Kalotina it forms a beautiful gorge. West
from Kalotina Nishava leaves the territory of Bulgaria and passes through Caribrod
and Pirot in a field where it flows into the river Temska. After the region of Bela
Palanka Town it form the impressive Sichevska gorge. In Serbia Nishava passes
through the cities of Caribrod, Pirot, Bela Palanka, Nishka Banya and Nis.
The main factors that generally intensify the torrential processes are changes in land
use, soil sealing, urbanization and transport infrastructure.
Changes in land use
Land use in Nishava river basin is presented in Appendix 8 of CORINE - 2006
database. Data analysis shows that more than half of the size of the basin /54.7% of
total area/ is occupied by forests. Mixed forests /5.4% of forest area/, followed by
deciduous forests /3.5% of forest area/. The second largest area is occupied by
arable land, including rainfed and irrigated fields. In total they comprise of 1214.0
km2 /Fig.4/. Woodland and arable land are widely presented in the river basin. A
considerable area is occupied by natural grasslands and pastures /524.5 km 2/,
which, like forests and farmland, are ubiquitous throughout the basin.
Land use in Nishava river basin /CORINE 2006/
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Urban land /incl. settlements, industrial sites and road infrastructure, etc./, ponds and
areas occupied by bare rock, sand, and areas with sparse vegetation cover an area
less than one percent of the territory.
Changes in land use in Nishava river basin /CORINE 2000 and 2006/
2006, 2000, Difference,
Category of land use km2 km2 km2
Urban area 101,29 90,6 + 10,69
542,7
466,6
Natural and artificial grass area + 76,10
Arable land 1214,02
1236,7
-22,68
2207,5
Forests 2271,1
-63,60
Coast areas, bare rocks and areas of sparse 37,24
39,6
vegetation -2,36
10,96
Aquatic area 9,1
1,86
4 113,7
Total area of the basin 4 113,71 1
Changes in land use are determined on the basis of data on land cover, according to
Corine – 2000. Analysis of the data in the table shows that changes in the main land
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use categories compared to the same categories in 2000 were negligible. Increased
area is in urbanized territory with 11 km2. Some increase was been observed in the
pasture and grassland /natural and man-made/, which in 2006 increased by 76 km2.
In terms of flood formation, forests play a very important water regulating role. Data
from CORINE show that total forest land in 2006 decreased by about 64 km2.
Changes in the area of all forest types, however, is minor.
Categories of land use in river basin Nishava on CORINE 2000 and 2006
Category 2000 - % of 2006 - % of Difference in %
total area total area
1. Settlements with
0,030663 0,029575 -0,001087821
dense urbanization
2 Settlements with less
1,724978 1,942239 0,21726071
dense urbanization
3 Industrial ot
0,193782 0,205482 0,011699849
commercial objects
4 Transport
infrastructure and 0,016126 0,016126 1,96021E-07
related land
5 Airports 0,053472 0,055091 0,001618978
6 Quarries and opencast
0,17452 0,203593 0,02907369
mining
7 Green area in
0,032554 0,019134 -0,013419653
settlements
8 Area for sports and
0,010272 0,010226 -4,64341E-05
tourism
9 Unirrigated arable area 6,599017 6,526317 -0,072699514
10 Vineyards 0,060472 0,037202 -0,023270167
11 Fruit trees and berries 0,017743
12 Pasture 2,820408 2,669824 -0,150584149
13 Complexes of
fragmented agricultural 10,9228 10,61248 -0,310325963
land
14 Agricultural land with 12,48132 12,31762 -0,163698457
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significant areas of
natural vegetation
15 Deciduous forests 33,62288 33,7931 0,170219704
16 Coniferous forests 1,730484 1,864477 0,133993036
17 Mixed forests 2,695711 2,913147 0,217436014
18 Natural grass area 8,489909 10,50342 2,013509696
19 Transitional tree-shrub
17,15798 15,09172 -2,066263929
vegetation
20 Beaches, dunes, sand 0,017651 0,011399 -0,006251881
21 Bare rocks 0,135157 0,160906 0,025749138
22 Areas with sparse
0,809093 0,732839 -0,07625432
vegetation
23 Inland moors 0,047042 0,089926 0,042883876
24 Rivers 0,006745 0,006745 5,34698E-08
25 Aquatic area 0,16696 0,169674 0,002714237
At the same time, changes associated with deterioration of the structure,
completeness and productivity of intact natural communities should be taken into
consideration.
As a result of these changes, flood retention and bioecological functions of forests
have weakened and the destructive activity of the torrential erosion has
strenghtened.
Soil sealing
Soil sealing in recent years is estimated to be a substantial global threat not only to
soils but also to the intensity of formation of surface runoff due to heavy rains.
Anthropogenic land /soil/ sealing is related to the use of soil for sustainable
development of urban construction, industrial and infrastructure construction, trade
and transport sectors, road and rail network and others.
The built area in Nishava River Basin in 2006 represents about 2.5% of the total
basin (101.29 km2). Compared with 2000, the growth rate of soil sealing is
insignificant, the increase is 10.69 km2. Durable built-up areas in 2000 accounted for
2.2% of the total area. This slight increase is primarily due to increased built-up area
of settlements with free construction by about 8.94 km2. The area of industrial and
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5. Програма за ТГС по ИПП
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commercial buildings and road infrastructure has insignificantly increased in 2006,
and the area of sports and recreation and urban fabric, slightly decreased.
Urbanization
Generally, urbanization increases the frequency of flood occurrence and reduces the
time of the formation of high waves due to soil sealing and therefore increases the
amount of surface run-off formed during intense rainfall, although in many cases
measures are taken to reduce the negative consequences. There are seven
administrative districts and eleven municipalities on the territory of Nishava River
catchment. Annex 10.
Flooded river terraces of Nišava river and its tributaries are the preferred place for
business development. The settlement network is presented by 307 settlements
/incl. 7 cities/. The density of the urban network is 7.5 settlements/100 km2.
Almost half of the settlements /145 cities/ are placed or partially placed in 200 m
buffer zone around the rivers. The total area of these settlements constitute 72% of
total area of the settlements in the Basin Nišava. Some of the most urbanized areas
in the basin are located in the buffer zone of 200 m from the river /7 cities/.
Therefore, urbanization is a factor for intensifying the risk of increased occurrence of
floods in the basin.
Up to the town of Dimitrovgrad /Serbia/, there are 32 settlements, including 4 cities
within the catchment. Of these, 17 settlements lay within the buffer zone of 200
meters, including 4 cities.
Transport Infrastructure
Main elements of transport infrastructure in Nišava River Basin are roads many
of which have been built since ancient times and most of them pass along the river
valleys. Appendix 12
The total length of road network is 946, 18 km. Today through the territory of the
basin passes Corridor № 10 /E 80/ from Nis - Dimitrovgrad, Pirot - Dragoman to
Sofia. The first class road from Nis to Zajecar. Through the territory of the basin pass
secondary roads from Pirot - Leskovets, Dimitrovgrad - Pirot and several regional
routes.
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6. Програма за ТГС по ИПП
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The length of the railway lines passing through the basin is 175.847 km. The
railway line from Nis-Bela Palanka, Pirot-Dimitrovgrad - Dragoman to Sofia and
others pass through the territory of the basin.
Transport infrastructure ontensifies the processes of flood formation and their
catastrophic effect. The existing road network in Nishava river basin has unapropriate
drainage systems, which are the reason why during intense rainfall surface waters
from other areas are redirected to the basin and can cause a rapid rise in river water
level and flood events. However, it should be taken into consideration that the
negative effects of the road infrastructure can not be completely eliminatedand in
many cases it is inappropriate to build expensive drainage systems. It should also be
taken into account that the transport infrastructure in case of flooding is crucial for
evacuation of the population and access to emergency service.
Negative effects of past floods
Information bout the negative effects of past floods in Nishava River Basin was not
found in the sources of information about past floods. However, it can be concluded
that the protected areas of primary importance are the categories "human health"
and "business".
In can be concluded from the history of floodings that the majority of settlements in
both the upper, middle and downstream of the Nisava river were affected by major
floods in the river basin, occurred during the 19th and 20th century. Although the
sources of information on past floods do not specify an exact number of drowned
people, it is clear that in all past catastrophic flood had victims.
For the category "business" in these catastrophic floods farm buildings and
agricultural land were destroyed, damaged or allocated and livestock drowned.
Damaged road infrastructure /roads and bridges/ were reported In all recorded
floods.
Potential negative consequences
The potential risk in Nishava River Basin is defined in terms of protected categories
"human health", "business", "environment" and "cultural heritage".
Assuming the criterion of 100 affected people for one village as a threshold value,
then in the 48 settlements in the river basin, the number of potentially affected by
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7. Програма за ТГС по ИПП
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flooding is greater than 100. The six cities located in the basin are characterized by a
significant potential risk for the category "human health" as the number of potentially
affected residents from flooding is greater than 500. The number of people affected
for category of "human health" is presented in the table below. The potential flood
risk is significant in the villages are located in the middle and lower parts of the river.
Potentially affected residents in the flood basin of the river Nisava
Settlements Size of Area of the Population, Occupancy Number
within a 200 m urban city, located number of density of of people
buffer zone from area, in 200 m people population, affected
rivers km2 buffer zone prs/ km2
of rivers,
km2
Godech 6,14 3,72 4425 720 2677
Bela palanka 2,17 0,69 8112 3731 2575
Trun
Dimitrovgrad 1,91 0,93 6247 3270 3052
Pirot 7,96 1,87 38432 4828 9039
Nis 22,32 1,87 177972 7974 32417
Potential flood risk exists for the protected category "business" in the river basin
Nišava. The greatest damage will be for industrial sites. Their total area which falls
within the buffer zone of 200 m from the river is 1,09 km2. These are mostly industrial
areas of cities located in the basin – cities of Godech Tran, Dimitrovgrad, Pirot and
Nis.
Potential risk in Nishava river basin
Criterion Total In buffer %
ed area
Protect
200m
Industry
activity
Economic
Industrial and 8,45 1,09 12,9
commercial objects,
km2
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8. Програма за ТГС по ИПП
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Transport infrastricture
Lenght of the 946,176 271,426 28,7
transport
infrastructure, km
Total lenght of the 175,847 61,48 35,0
railway network, km
Agriculture
Complexes of
fragmented
agricultural land, km2 436,57 55,86 13,0
Vineyards, km2 1,53 0,31 20,3
Non-irrigated arable
land, km2 268,47 39,90 14,9
Agricultural land with
significant areas of
natural vegetation,
km2 506,72 102,82 20,3
Pasture, km2 109,83 10,47 9,5
Fruit and berries
plantations 0,73 0,11 15,1
Protected areas Natura 2000
ent"
"Environm
Birds Directive 467,28 58,10 12,4
Habitats Directive 453,05 70,73 15,6
Protected areas /R.
Serbia/ 823,94 74,69 9,1
The flood risk is also significant for the transport infrastructure, respectively, 28.7% of
road network and 35% of the railway network is located 200 meters potentially
flooded area. The potential risk of the different classes road network is presented in
the table.
Potential risk of flooding to transport infrastructure in the Basin Nishava
Class roads Length of road network, Length of % Of the
km road length of the
network, road network
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9. Програма за ТГС по ИПП
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located in located in
the buffer bufernnata 200
zone 200, m area.
km
Highway 6,843 1,369 20
Highway project 10,057 2,645 26,3
Second class roads 304,300 86,092 28,3
First class roads 170,232 40,379 23,7
Third class roads 454,742 140,939 31,0
With regards to protected category "Environment" the flood risk is also
significant because there are three sites which may discharged polluted water in the
upper part of the river and thus present risk to aquatic ecosystems.
Risk of flooding for Natura 2000 sites
Name Area km2 Area km2 in 200 m % of area in 200 m
buffer zone buffer zone
Birds directive 2009/147/ЕС
Noevci 3,69 0,82 22,2
Ruy 173,45 18,38 10,59
Rayanovci 90,24 10,70 11,85
Ponor 128,19 16,71 13,03
West Balkan 71,69 11,47 15,99
Habitats directive 92/43/ЕЕС
Rebro 2,13 0,91 42,72
Dragoman 109,15 13,61 12,46
West Balkan 17,72
Mountain and 274,21 48,60
Forebalkan
Kurvav kamuk 37,80 2,12 5,6
Ruy 17,06 5,25 30,77
Lubash 12,67 0,20 1,57
Protected reas /R.Serbia/
Erma river gorge 0,15 0,11 73,3
Temna dupka 0,19 0,03 15,78
Kotlite 0,17 0,15 88,23
Zaskogo 0,27 0,11 40,74
Uruchnik 0,16 0,08 50,00
Klisura Osanicke 9,1
80,84 7,36
reke
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10. Програма за ТГС по ИПП
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Bifurkacija reke 90,02
74,21 66,81
Nerodimke
So far, the flood protection measures taken in Nishva River Basin are engineering
measures /corrections of watercourses, dams and dykes/. River flow is regulated
within the cities of Godech and Dimitrovgrad.
The analysis of the functioning system of measures for flood protection shows that it
is not efficient, especially in extreme floods with very little repetition. Acceptable level
of protection could be achieved only after detailed mapping of the flood risks under
various scenarios and on this basis to determine an adequate scheme of measures
(hydro-technical) and non-engineering measures and safeguards.
The material was prepared by Ivan Babukov ET, together with the Managing Team Project and
presents the results of development of the project "Assessment of flood risk - the basis for sustainable
development in the upper basin of the river Nišava" funded by the CBC program under IPA , Bulgaria,
Serbia.
This publication was supported by the European Union by CBC Programme CCI No
2007CB16IPO006. The contents of this publication is the sole responsibility of NIS at Sofia University
"St. University and in no way should be seen as an expression of opinion of the European Union or the
MA Program.
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