1. TORRENTIAL FLOODS IN SERBIA: FREQUENCY AND CONTROL
3rd Conference of teh World Associaton of Soil and Water Conservation
TORRENTIAL FLOODS IN SERBIA: FREQUENCY AND CONTROL
Kostadinov Stanimir, Ristić Ratko and Petrović Ana
University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, Belgrade, Serbia

2. 3rd Conference of teh World Associaton of Soil and Water Conservation
3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Water erosion processes prevail in the area south from the Sava and the Danube, while wind erosion processes prevail in the Autonomous Province of Vojvodina in the north. About 12,000 torrents in Serbia were registered ( in the frame of cadastres of torrents made in ).

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Torrents often cause catastrophic torrential floods which not only cause material damage but also casualties. The frequency of torrential floods, as well as other natural disasters, in the last decades have increased in Serbia due to climate changes.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
This paper shows :
-the distribution and intensity of water erosion,
-distribution, properties and frequency of torrential floods in Serbia,
- and possibilities of its control.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Material and methods
Methodological approach in this work comprises of the following:
The use of existing erosion map of Serbia,
Detailed investigation of previous torrential flood research in Serbia,
Compilation of data on torrential floods and its analysis,
Analysis of current state of erosion and torrential floods and the possibility of prevention.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Table 1 Distribution of Water Erosion Processes in Serbia
Category
Erosion Processes Intensity
Area
km2 % I
Excessive Erosion
2,888.0
3.27 II
Intensive Erosion
9,138.0
10.34
III
Medium Erosion
19,386.0
21.94 IV
Weak Erosion
43,914.0
49.78 V
Very weak Erosion
13,035.0
14.75
Total
88,361.0
100

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
The fundamental property of torrents:
- direct link among phenomena in the watershed and in the stream, - torrential floods, - torrential character of hydrological regime → large range of yearly discharge and short duration of flood waves → ratio of flow and flood peaks is of the order of magnitude 1: great channel slope, ranging from 1 to 15% or more

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Damages caused by erosion and torrents
General damages
Soil loss
Water loss
Disturbance of runoff regime
Reservoir siltation
Irrigation and drainage systems siltation
Ecological effects
On-site effects
Environment degradation
Off-site effects
Mechanical pollution of water in the streams and reservoirs
Chemical pollution of water by manures and fertilizers
Chemical pollution by pesticides

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Table 2. Main characteristics of reconstructed torrential floods in Serbia
Water course
Profile
Date of appearance
Magnitude [km2]
Qmax
[m3.s-1]
qmaxsp
[m3.s-1.km-2]
Duration/
Intensity
Ljestarska Valley
Vladicin Han
2.64
16.16
6.12
90 min; 1.17 mm.min-1
Kalimanska River
Summer 1929
16.04
149.0
9.3 /
Sejanicka River
Grdelica
12.51
62.75
5.02
90 min; 1.01mm.min-1
Manastirica
Brezdje
29.5
154.9
5.25
180 min; 0.75mm.min-1
Ribnica
Pastric
104
418.08
4.02
Čađavica
Krupanj
24.04
141.45
5.88
Kržava
12.69
61.32
4.83
Brštica
9.54
29.2
3.06
Vlasina
Vlasotince
1,050.00
950.0
0.905
240 min.
0.92mm.min-1

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Map of Serbia and areas jeopardized by torrential floods in the period

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Table 3. Distribution of registered torrential floods in the periods
No.
Time period
Number of torrential flood events
Average per year
Casualties 1. 33
2.06
>22 2.
175
5.83
>51 3.
384
12.80 36 4.
297
12.38 27
Total (100 yr)
889
9.89
136
The average number of torrential floods per period has increased almost 6 times from the first period (2.06) until the last (12.38). More frequent occurrence of torrential floods could be explained by the changes in climate conditions. The decrease in total annual precipitation has been recorded but they are occurring in the form of heavy showers forming a sudden water concentration in small basins on steep slopes having torrential floods for consequence.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Representative examples are the torrential floods in Western Serbia, particularly in the municipality of Krupanj, which covers a territory of 342 km2. A few settlements were struck by floods on the local torrents (Čadjavica, Kržava, Brštica) on May 15th, 2014, causing death of two people, almost 900 hectares of arable land flooded or damaged by landslides, 333 flooded buildings (of which 40 severely damaged or destroyed), 120 km of destroyed or damaged roads, 14 destroyed and 8 damaged bridges, 5 km of destroyed river regulations (mostly trapeze channels lined with stone masonry) and 300 evacuated inhabitants. In addition, 269 landslides were activated during the heavy precipitation and flood waves propagation. The estimated material damage amounted to more than 30 million €.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

18. TORRENTIAL FLOOD CONTROL AND LEGAL FRAMEWORK
3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
TORRENTIAL FLOOD CONTROL AND LEGAL FRAMEWORK
In the process of the implementation of the Directive of EU on the assessment and management of flood risks(2007/60/ЕК):
The starting point is preliminary risk assessment, which will be used in
Vulnerability mapping (which is the representation of the probability, i.e. frequency of torrential floods),
And flood risks (which includes additional information on casualties, material damage, and similar) ; which will serve as the base for the flood risk control

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Belgrade, August 22-26, 2016
The first activities on the implementation of the Directive is information and data collection on the floods which have occurred in the past, in particular the ones with the high probability of repetition and the ones with the catastrophic consequences.

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Belgrade, August 22-26, 2016
The important component in flood risk management according to the EU Directive is communication and raising the public awareness on the flood risks.
Here, the web portal of the Republic Hydrometeorological Service of Serbia issues the “Warnings and Announcement” directed to public only concerning the floods on big rivers and the announcements of the possibility of heavy precipitation in certain regions by giving weather alerts of various warning degrees.

21. 3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
FORECAST AND WARNING ON TORRENTIAL FLOODS IN SERBIA
When making a forecast about torrential floods,hydrometeorological, geological and geomorphological and other conditions in the basin leading to the torrential flood waves are studied with the most important output data of the calculation is the maximum discharge which has a certain possibility of occurrence. The threshold for issuing the warning should be defined based on the occurrence of a small probability maximum discharge which have been previously defined.

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Belgrade, August 22-26, 2016
The flooding zone can be defined for the areas of torrential stream using :
the hydrological and
hydraulic calculations for a certain torrential watershed, and
the digital terrain model ( DTM).
In the high risk areas it is necessary to determine the critical precipitation quantity in the given basin which could lead to the occurrence of the maximum discharge and the time lag which refers to the time for the transformation of precipitation into the maximum discharge.

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Belgrade, August 22-26, 2016
In order for this to be successfully realized, it is necessary that all local governments (municipalities) to establish constant precipitation and discharge monitoring in all basins estimated to pose the risk of torrential floods. The monitoring data give us the possibility of an early announcement of torrential floods which will help with the direct defence during the flood and there would be more time for the population evacuation from the endangered areas.

24. 3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
It is also necessary to determine the levels of warning from small to extreme risks. The forecast of torrential floods is of great significance to local communities and for preventing damages in economy but it requires considerable funding and modern equipment. Since it abrupt character, timely forecast of torrential floods is more demanding than the forecast of floods on big rivers (The Sava, Danube, Velika Morava, and Tisa Rivers).

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Belgrade, August 22-26, 2016
PROTECTION AND DEFENCE AGAINST TORRENTIAL FLOODS
The nature of torrential floods is such that they cannot be controlled and that the complete protection and defence against torrential floods does not exist. However, the destructive effect of this phenomenon can definitely be mitigated.
On the other hand it is necessary to point out that due to their nature, the methods applied to the big rivers flood defence cannot be applied to the defence against torrential floods.

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Belgrade, August 22-26, 2016
During the period of 100 years ( ) 1,501, m3of technical and 120, ha of biological works have been performed. The works on torrent control were in expansion in the 50s and 60s of the last century in order to record considerable downsize despite the problems erosion and torrential floods pose to agriculture, water management, traffic, population and society in general.

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Belgrade, August 22-26, 2016
Detrimental consequences of torrential floods to society could be avoided of considerably reduced if the risk areas are identified, constant precipitation and discharge monitoring organized which enables efficient forecast and early announcement of torrential floods and thus provide timely warnings. The education of local population on the measures to be undertaken in case of torrential floods is very important.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Defending against torrential floods
Having in mind the character of torrents and the fact that torrential floods occur suddenly and quickly after intensive precipitation in a basin, the best defence against torrential floods is prevention. Prevention consists of erosion control works and measured applying the principle of integral torrential catchment management ( integrated torrent control).

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
Integral system of torrent control consists of the design and execution of three group of works:
Technical works in hydrographic networks of torrents (check dams, sills, correction of lower parts of the torrents, small and micro water reservoirs, retentions, bank revetment),
Biotechnical works (gully control, wattles and small stone walls),
Biological works (afforestation of bare land, grassing, amelioration of degraded forests, meadows and pastures, establishment of orchards on the terraces).
In addition to the above, the strategy of torrent control also include:
administrative measures i.e. to adopt and apply different regulations and restrictions aiming at soil conservation (prohibition of grazing, prohibition of lopping, protection forests, etc.);
educational and advertising measures include courses, lectures, showing of films, exhibitions, and other activities in erosion control, prevention of torrential floods, drought and economic backwardness. ( Kostadinov,S., 2003, 2007, Kostadinov,S., et al 2013).

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
1955
1957
1978
1958
Effect of afforestation of bare land in the Vlasina river watershed

34. In order to achieve the required goals it is necessary to undertake the following activities:
The change of legislature with the aim to increase the works on the prevention of torrential floods:
The preparation and passing of the Law on water management financing including the financing of the works on erosion control and regulation torrent channel control (torrential flood control);
- To make changes to the existing Law on Waters (in particular the Article 23 by which the responsibility concerning erosion and torrent control fall into the hands of local government which do not have either professional or financial resources to deal with the problems which was particularly evident in May and September 2014 and March 2016);

35. 2. Organisational and administrative measures
Having in mind that soil erosion and torrents and torrential floods cause damage to economy and the society in general, the works on erosion and torrential floods control should be financed from all economy sectors: water management, forestry, agriculture, energy sector, urban planning, traffic, as well as all other which suffer from the damages caused by torrential floods and soil degradation.
- Integral solution to the problem of erosion and torrential floods protection, as well as the decades of neglecting this problem, require separate organizational units (Authority or Directorate) within the Ministry of Agriculture and Environmental Protection;

36. 3. The preparation of strategic documents
In order to successfully realise the Integrated management in torrential catchments (erosion and torrent control) it is necessary that the Republic of Serbia prepares the following plans as soon as possible:
National Strategy for Erosion and Torrent Control,
Erosion Map of the Republic of Serbia,
Torrent Cadastre of Serbia,
The Cadastre of Erosion Control Works in Serbia.

37. 4. The obligations of local governments
The preparation of The Plans for Declaration of Erosion Areas and Operational Plans for the Flood Control on Torrents;
The implementation of urban planning and communal order (strict construction control in blue zones; prohibition of garbage disposal within the bank zone and river beds);
- The coordination of spatial plan and urban documentation with The Plans for Declaration of Erosion Areas and Operational Plans for the Flood Control on Torrents.

38. Building up local government capacities for tackling the problem of erosion and torrents by employing specialized personnel (BSc Eng. Forestry in ecological engineering for the protection of soil and water resources; BSc Eng. in water management for erosive areas; BSc Eng. Forestry for erosion and torrent control; the above stated personnel is educated at the Faculty of Forestry in Belgrade for more than 60 years attending educational programmes coordinated with the leading world’s universities in the field).
Installing the system for early announcement of torrential floods in torrential basins with the realistic risk of torrential floods occurrence. Having in mind that many local governments are not in the position to undertake the investment for those particular purposes, the state, i.e. the competent ministry, i.e. The State Water Directorate must help the cause.

39. - The realisation of “horizontal” coordination at the level of the Ministry of Agriculture and Environmental Protection concerning the coordination of organisational units within water management, forestry, and agriculture (Water Directorate, Forest Management, Agricultural Land Management) in order to achieve the adequate treatment of the area around mountainous basins concerning prevention of erosive processes and torrential floods

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
CONCLUSION
Natural features of the Serbian territory and inadequate soil and land usage in the past conditioned the occurrence of intensive soil (water and wind) erosion. The result are torrents (more than 12,000 on the territory of Serbia) causing torrential floods often with catastrophic consequences. In the last 20 years and more, the intensity and frequency of torrential floods as well as other natural disasters have considerably increased.
Having in mind on-going climate changes, the increase of extreme precipitation , intensifying of erosive and torrential processes, and as consequences, increasing of frequency of torrential floods can be expected.Because of the torrent and torrential flood characteristics, the best control is a constant effort on their prevention. Prevention is regular and constant work on erosion and torrent control

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Belgrade, August 22-26, 2016
In order to successfully realise the Integrated management in torrential catchments (erosion and torrent control) it is necessary that the Republic of Serbia prepares the following plans as soon as possible:
National Strategy for Erosion and Torrent Control,
Erosion Map of the Republic of Serbia,
Torrent Cadastre of Serbia,
The Cadastre of Erosion Control Works in Serbia.

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3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
ACKNOWLEDGEMENT
 This paper is part of the project “The Research on Climate Change Influences on Environment: Influence Monitoring, Adaptation and Mitigation” (43007), subproject No. 9: “Torrential Floods Frequency, Soil and Water Degradation as the Consequence of Global Changes“, financed by Ministry of Education and Science of the Republic of Serbia as part of the Integrated and Interdisciplinary Researches programme for the period from 2011 to 2016.

43. 3rd Conference of teh World Associaton of Soil and Water Conservation
3rd Conference of the World Associaton of Soil and Water Conservation
Belgrade, August 22-26, 2016
THANK YOU VERY MUCH!