275
1 INTRODUCTION
The aim of this paper is to analyze the specific
characteristics of search and rescue operations on
frozen rivers, with a particular emphasis on the
application of rescue techniques and the importance of
civil-military cooperation. The research will cover the
natural features of frozen rivers, typical accidents,
intervention methods, the organization of rescue
teams, as well as practical examples, with the ultimate
goal of proposing measures to improve existing
capacities and protocols.
2 NATURAL CHARACTERISTICS OF FROZEN
RIVERS
Formation of ice on rivers represents a complex
hydrological and climatic phenomenon that affects not
only human safety but also river traffic, infrastructure,
and the environment. Unlike still waters, river ice is
unstable, asymmetrical, and highly unpredictable due
to the dynamics of the water flow beneath the surface.
2.1 Phases of ice formation and types of river ice
The formation of ice on rivers takes place through
several phases, the course of which depends on the air
Search and Rescue on Frozen Rivers
S. Šoškić, N. Popović Paunić, S. Bajrami & M. Kresojević
Military Academy, Belgrade, Serbia
ABSTRACT: Rescuing people and objects on frozen rivers is a complex activity that involves intervention in
unpredictable and often extreme conditions. In this regard, every country with river waterways must to some
extent think about ice during the winter months, about the impact of ice on river navigation, and about possible
accidents that occur during that period. Frozen rivers, as a natural phenomenon, are often places where accidents
occur due to ice breakage, collapse of objects, or traps for people who find themselves in inadequate conditions.
In such situations, timely reaction and well-organized rescue teams are required. The topic is important for the
entire social community due to the increasing frequency of water accidents during the winter period and the
inclusion of all segments of society, especially the military and police, in search and rescue operations, which
would be the primary response force during water accidents or as support for civilian structures that are
threatened by the appearance of ice on the water. Civil-military cooperation in these cases involves pooling
resources, knowledge and capabilities in order to increase the efficiency of rescue operations. The aim of this
paper is to analyze the challenges and techniques of rescue on frozen rivers and highlight the importance of civil-
military cooperation in these activities. It will be investigated how coordination between different structures
(military, civilian and volunteer) can contribute to greater population safety, reduction of losses and more efficient
use of all resources.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 19
Number 1
March 2025
DOI: 10.12716/1001.19.01.33
276
temperature, the speed of the water flow, heat
exchange with the atmosphere, and the characteristics
of the riverbed. Recognizing these phases is of key
importance for predicting risky phenomena and
assessing the safety of navigation.
Figure 1.
1. Initial crystallization – With the drop of
temperature below 0 °C, the formation of ice
needles begins in the coastal and calm parts of the
flow. This phenomenon represents the first phase of
icing, still mechanically insignificant.
2. Formation of frazil ice – With further cooling, ice
needles join into flocs that form a loose surface layer
– frazil ice. It is visually noticeable but has
insufficient load-bearing capacity.
3. Appearance of anchor ice – Under conditions of
strong cooling and low turbulence, ice can form
below the water surface. Such ice, known as anchor
ice, is not visible but can endanger the operation of
underwater infrastructure.
4. Formation of congelation ice – With stable
temperatures and continuous heat loss, a solid,
transparent ice layer forms – congelation ice, which
evenly covers the river surface and has the greatest
load-bearing capacity, although it may contain
hidden cracks.
5. Ice floes and ice drift – Under unstable conditions,
ice breaks and forms floes that move downstream
(ice drift). Floes can damage vessels and
infrastructure, and their accumulation can lead to
ice jams and the need for intervention.
Table 1.
Phase
Description
Place on the
river
Risks and
impact
1
ice needles in
cold, still water
coastal zones
safe phase
2
Crystals form a
floating layer
Slow
currents
Low load-
bearing capacity
3
Ice beneath the
surface,
invisible
Shallow
areas,
riverbed
Hazardous to
infrastructure
4
Strong, stable
ice
Entire river
surface
Potential cracks
5
Ice breaking
and movement
Middle and
lower river
course
High risk
2.2 Basic Definitions and Types of River Ice
The occurrence of ice on rivers holds significant importance
in hydrological, navigational, and safety contexts. Therefore,
the terms describing the dynamics, condition, and shape of
ice formations are clearly defined in professional and
scientific literature. Proper understanding of these terms
forms the basis for effective risk management, protection of
infrastructure and vessels, as well as the organization of
rescue and technical intervention operations.
2.2.1 Basic Definitions of Ice Phenomena
− Ice Drift – a dynamic phenomenon in which ice
formations (ice floes, ice sheets, fragments of solid
ice cover) move downstream along the river. It
occurs at the beginning of the freezing process and
during the thawing phase. Ice drift can cause
mechanical damage to hydraulic structures,
bridges, and vessels, as well as blockages of the
river channel.
− Ice Drift Period – the time interval during which ice
is actively moving along the watercourse. During
this period, ice jams may form, leading to water
accumulation and potential upstream flooding.
− Ice Cover – a phenomenon in which the surface of
the river is partially or completely covered with
static, immobile ice. Unlike ice drift, ice during this
phase remains still, but it still poses a mechanical
obstacle and a threat to the stability of structures
and the safety of people.
− Ice Cover Period – the time interval in which the ice
on the water surface remains stationary, without
significant changes in position or structure.
− Ice Jam – a localized accumulation of ice floes and
fragments in a narrow section of the river channel,
obstructing the free flow of water. The formation of
an ice jam often requires intervention by icebreakers
or controlled blasting of the ice.
2.3 Climate Conditions and Ice Cover Phenomena in
Serbia
The occurrence of ice on rivers in Serbia is influenced
by a combination of climatic factors, hydrological
characteristics of river flows, and local geographical
conditions. River freezing most commonly occurs
during the winter months, from December to February,
during prolonged periods of low temperatures [7].
According to data from the Republic
Hydrometeorological Institute, stable ice usually forms
after at least 7 consecutive days with an average air
temperature below –5°C, under conditions of weak
water currents and absence of wind.
2.3.1 Historical and Statistical Data
Analysis of the period from 1991 to 2004, based on
observations from the water gauge stations in Novi Sad
and Zemun, shows the following:
Table 2.
Location
Average Onset of
Ice Cover
Average Duration
of Ice Cover
Maximum Duration
of Ice Cover
Novi
Sad
Beginning of
January
7–10 days
Up to 20 days
Zemun
Mid-January
5–8 days
Up to 15 days
During the specified period, ice cover was in most
cases of short duration and limited to narrow sections
277
of the river. It was most commonly recorded in areas
with reduced flow and where the river channel is
narrower [11].
2.3.2 Example: Winter of 2011/2012.
The winter of 2011/2012 was one of the most
extreme ice periods in recent Serbian history. The
Danube near Belgrade and Smederevo was covered
with ice across more than 90% of its width,
temperatures ranged from –10°C to –20°C, and the
snow cover exceeded 30 cm. Navigation was
suspended, and an emergency ice congestion defense
was declared.
This event illustrates the impact of climate extremes
on river traffic and the need for rapid intervention.
2.4 Historical Examples of Extreme Winters in Serbia
Historical data show that extremely harsh winter
periods have occasionally been recorded in the
territory of Serbia, during which rivers were
completely frozen, ice cover persisted for extended
periods, navigation was suspended, and serious
consequences occurred for river infrastructure and
public safety [11].
These events serve as an important basis for
modeling emergency situations caused by climate
extremes.
− Winter 1928/29 – The Danube was frozen for more
than 60 days, ice thickness exceeded 40 cm;
complete traffic suspension and major damages. It
is considered a reference case in extreme event
analyses.
− Winter 1956 – Temperatures dropped below –25°C,
the Danube and Sava rivers were frozen; ice
thickness over 50 cm, bridges and river ports were
damaged.
− Winter 1984/85 – Ice jams on the Ibar, Tisa, and
Danube rivers; interventions included blasting and
the use of icebreakers.
These examples highlight the need for risk
management plans to be based on extreme scenarios,
not just average climatic values.
2.5 Impact of Ice on Navigation and Infrastructure
Freezing of rivers has significant consequences for
river traffic, hydraulic structures, and public safety,
requiring a systematic approach to monitoring and risk
management.
1. Suspension of Navigation
The formation of ice cover and ice drift leads to
complete or partial suspension of river traffic,
causing economic losses and supply interruptions.
2. Ice Jams
The accumulation of ice sheets in narrow river
sections causes blockages, water level rises, and
flood risks. Emergency measures are taken when
over 60% of the surface is covered by ice.
3. Infrastructure Damage
Moving ice masses, especially during ice drift, can
damage bridges, pontoons, docks, and other
structures, as well as cause erosion of the riverbed.
4. Controlled Blasting
To clear the river channel, controlled ice blasting is
carried out according to a professional plan and
under the supervision of specialized teams.
5. Use of Icebreakers
Icebreakers break the ice to allow water flow and
vessel movement. In Serbia, due to limited
resources, private vessels and capacities from
neighboring countries are often engaged in
cooperation with the Water Directorate.
6. Preventive Measures and Monitoring
− Installation of shoreline barriers to slow ice
movement
− Monitoring using radar systems and drones
− Timely issuance of warnings and forecasts
Effective management of winter risks requires
coordination of all relevant services and consistent
application of preventive and intervention measures.
Table 3.
Consequence /
Phenomenon
Description
Protection Measures /
Response
Suspension of
Navigation
Interruptions in river
traffic due to ice.
Temporary suspension of
navigation; organization of
alternative transport.
Ice Jams
Blockage of the river
channel and flood
risk.
cebreakers, controlled
blasting, water level
monitoring.
Infrastructure
Damage
Impact of ice on
bridges, pontoons,
docks.
nhanced maintenance and
protective structures.
Controlled
Blasting
Removal of ice masses
in critical sectors
Carried out by expert teams
according to a plan and in
coordination with
authorities.
Use of
Icebreakers
Breaking ice to
prevent blockages and
allow water flow.
Engagement of domestic
and regional capacities.
Preventive
Measures
Risk reduction before
critical situations arise
Shoreline barriers, radar
and visual monitoring,
warning systems
3 HAZARDS AND TYPICAL ACCIDENTS ON
FROZEN RIVERS
Frozen rivers represent a high-risk environment for the
movement of people and vehicles, as well as for rescue
service interventions. The most significant hazards are
presented below:
Table 4.
Type of Hazard
Brief Description
Falling Through
Ice
Caused by thin or unstable ice. Results in falling
into the water and rapid hypothermia, with a high
risk of drowning. Most commonly affects
fishermen and recreational users.
Vehicle
Breakthrough
Insufficient ice load-bearing capacity leads to
cracking under the weight of vehicles.
Consequences include rapid sinking and difficult
rescue.
Ice Jams
(Barricades)
Ice floes get stuck in narrow river sections, causing
blockages and flood risks. Requires emergency
measures, including controlled blasting.
Isolation on Ice
Floe
Mechanical separation of an ice sheet from the
shore creates a dangerous situation for people on
the ice. Immediate rescue intervention is necessary.
„Ice Dams“ and
Ice Gates
A mixture of snow and submerged ice forms a
mass that blocks flow and causes ice floods.
Historically extremely dangerous, especially in
gorges.
278
Professional assessment of these hazards forms the
basis for planning effective search, rescue, and
population protection measures.
4 SEARCH AND RESCUE TECHNIQUES ON
FROZEN RIVERS
Conducting search and rescue operations on frozen
river surfaces requires a multidisciplinary approach
that includes precise risk assessment, use of specialized
equipment, and strict adherence to operational
procedures [2]/[3]. Below is the rescue operation
algorithm on a frozen river:
1. Preparation
− Activation of the rescue team.
− Checking the condition of equipment (ropes,
sleds, thermal suits, boats, probes).
− Deployment of drones for reconnaissance (if
available).
2. Situation Assessment
− Visual inspection of the ice (color, cracks,
structure).
− Measuring ice thickness at multiple points:
− Less than 12 cm – entry prohibited.
− 30 cm – vehicle movement permitted.
− Checking underwater currents and heat sources.
− Analyzing access routes and safety zones.
3. Approaching the Endangered Person
− Choosing the approach method (lying position
on sleds or using ropes and specialized
equipment).
− Communication with the shore team.
− Maintaining rope tension and movement
control.
4. Extraction and First Aid
− Securing the endangered person with a safety
harness.
− Coordinated extraction by the shore team.
− Removing wet clothing, putting on dry thermal
suits, gradual warming, and monitoring vital
signs.
Figure 2. River rescue operation algorithm
5 ORGANIZATION OF RESCUE TEAMS
The success of search and rescue operations on frozen
rivers largely depends on a precisely defined
organization, clearly assigned roles, and effective
coordination among participants [6]. Below is an
algorithm for organizing and conducting a rescue
operation on frozen rivers.
Figure 3. Algorithm: Organization and execution of rescue
operations on frozen rivers
The algorithm for organizing and conducting
rescue operations on frozen rivers consists of seven
phases.
− In the first phase, the rescue team is formed with
clearly defined roles: incident commander, ice
rescue team, shore support, and medical team.
− The second phase involves operational preparation,
including assessment of field conditions, definition
of safety corridors, and identification of risk zones.
− The third phase covers intervention planning,
which includes developing an approach and
communication plan, as well as an alternative
scenario.
− The fourth phase is the execution of the rescue
operation, during which the rescue team
approaches the victim, and the medical team
provides first aid.
− The fifth phase involves evacuation and medical
treatment, including thermal protection and
transport to a healthcare facility.
− The sixth phase is the operation analysis, which
includes a debriefing, identification of
shortcomings, and updating of operational
procedures.
− The final phase consists of training and drills
outside emergency situations, aimed at improving
readiness and adapting existing procedures.
279
6 STANDARD OPERATING PROCEDURES (SOP)
FOR SEARCH AND RESCUE ON FROZEN
RIVERS
Standard Operating Procedures (SOP) provide a key
framework for planning, coordinating, and executing
rescue operations on frozen river surfaces [2]/[3].
Below is the algorithm for a rescue operation on a
frozen river.
Figure 4. Algorithm: Standard operating procedures for ice
river rescue operations
The algorithm of standard operating procedures for
rescue on frozen rivers consists of four main phases.
− The first phase involves situation assessment,
including gathering hydrological and
meteorological data, visual inspection of the ice,
and measuring its thickness.
− The second phase covers approach planning and
organization, which includes marking safe
corridors, assigning team roles, preparing backup
equipment, and establishing communication
protocols.
− The third phase relates to executing the rescue
operation, during which the shore team secures
ropes and monitors the ice, while the rescue team
approaches the victim and provides first aid.
− The fourth phase includes evacuation and provision
of first aid, involving protection against
hypothermia, assessment of vital signs, and
possible transport.
− After the operation, a performance analysis is
conducted, along with internal documentation and
collection of feedback to improve procedures and
training.
7 CIVIL-MILITARY COOPERATION IN RESCUE
OPERATIONS
In cases of search and rescue on frozen rivers, civil-
military cooperation represents a key element of
successful intervention. The conditions under which
these operations are conducted require the deployment
of significant resources, expert personnel, and rapid
coordination among multiple different entities [5]/[10].
7.1 Role of Civilian Structures
Civilian structures, such as rescue services, fire units,
emergency medical services, and specialized volunteer
teams, usually play the primary role in responding to
water-related accidents. Their role includes:
− rapid receipt of notifications and assessment of
intervention priorities,
− direct execution of rescue operations within their
capacities,
− providing first medical aid,
− securing the accident site and requesting additional
support if their own capacities are insufficient.
7.2 Role of the Military and Police
The military and police represent extremely important
support segments in operations on frozen rivers. Their
engagement includes:
− Providing technical equipment (amphibious
vehicles, specialized sleds, helicopters),
− Supplying human resources with a high level of
training for operating in extreme conditions,
− Organizing the transport of endangered persons in
inaccessible areas,
− Securing the intervention area to prevent additional
incidents.
Police forces also take on the role of regulating
access to the accident site, managing the civilian
population, and supporting the coordination of
activities.
7.3 Key elements of successful cooperation
Successful civil-military cooperation involves:
− Clear command structure: establishing unified
command with clearly defined responsibilities.
− Joint training and exercises: regular joint drills of
rescue and military units to align procedures and
build mutual trust.
− Communication coordination: using shared
communication channels for timely information
transfer.
− Optimal resource use: coordinating available
equipment, specialized teams, and transportation
means.
− Rapid decision-making: establishing mechanisms
for urgent decision-making in crisis situations.
7.4 The importance of civil-military cooperation
Civil-military cooperation enables:
− faster response in critical situations,
− greater safety and protection of endangered lives,
− more efficient use of all available resources,
− strengthening society’s resilience to emergencies.
280
The integration of efforts between civilian and
military structures forms the basis for establishing an
effective risk management system on rivers during the
winter period.
8 EXAMPLES AND PRACTICES
To better understand the challenges and successful
implementations of rescue procedures on frozen rivers,
two significant practical examples are presented
below.
8.1 Rescue of an Animal from the Frozen Sava River in
Belgrade (January 2017) [6]
In January 2017, due to extremely low temperatures, a
dog became trapped on the frozen Sava River in
Belgrade. The intervention was carried out by
members of the Emergency Situations Sector, using
specialized equipment for moving on ice. Following
established procedures, the rescuer safely approached
and evacuated the animal, which was then cared for by
the veterinary service.
This incident illustrates the capability and
preparedness of rescue services in Serbia to respond
effectively under challenging conditions on frozen
water surfaces.
8.2 Rescue Operation on the Danube near Novi Sad
(Serbia, 2021) [6]
In February 2021, due to a sudden onset of weak ice,
several pedestrians found themselves in danger on the
frozen surface of the Danube near Novi Sad. The local
fire and rescue unit, in cooperation with members of
the Gendarmerie and River Police, organized a rescue
operation:
− a rescue line was established with ropes and special
ice carriers,
− amphibious vehicles were used for safe access,
− all those at risk were rescued, without serious
consequences.
This example shows the effectiveness of local civil-
military cooperation, but also the importance of
regular training and readiness of teams for work in
winter conditions.
8.3 Rescue operation on the frozen Lake Palić (February
2021) [6]
In February 2021, an incident occurred on Lake Palić
when a sailor became trapped on the frozen surface.
During the rescue operation, due to the insufficient
stability of the ice, members of the fire and rescue unit
also found themselves in danger. Thanks to the
coordinated intervention with members of the Sailing
Club, the person was successfully rescued and treated
for frostbite.
This event highlights the complexity of rescue
procedures under unstable ice conditions and the
necessity of specialized training and equipment.
9 CONCLUSION
Search and rescue on frozen rivers is an exceptionally
demanding activity that involves numerous risks both
for the endangered individuals and the rescue teams.
The specific natural conditions, unpredictable behavior
of the ice, and weather circumstances require well-
planned, coordinated, and technically equipped
interventions.
The implementation of standard operating
procedures enables more efficient situation
assessment, safe approach to the endangered, and
rapid evacuation. In this context, a key factor of success
is civil-military cooperation, which unites resources,
knowledge, and capabilities of various structures to
achieve a common goal – saving human lives.
Experience from practice so far shows that regular
joint training, establishment of clear communication
channels, and unified command significantly increase
efficiency in emergency situations on frozen rivers. In
the future, it is necessary to continue developing
integrated response systems and investing in
specialized equipment and training to further enhance
society’s ability to respond to the challenges posed by
the winter period on rivers.
REFERENCES
[1] Canadian Red Cross. (2018). Ice Safety and Rescue
Techniques: Manual for First Responders. Ottawa.
[2] Federal Emergency Management Agency (FEMA). (2019).
Search and Rescue Operations in Extreme Conditions
Manual. Washington, D.C.
[3] Hero Pinky – Novi Sad. (2015). Technical characteristics of
icebreakers. Internal documentation.
[4] International Maritime Rescue Federation (IMRF). (2017).
Guidelines for Ice Rescue Operations. London: IMRF
Publications.
[5] Jovanović, M. (2015). Fundamentals of water rescue.
Belgrade: Faculty of Safety, University of Belgrade.
[6] Ministry of Internal Affairs of the Republic of Serbia.
(2020). Rules of Procedure for Rescue Services in
Emergency Situations. Belgrade: Ministry of Internal
Affairs of the Republic of Serbia.
[7] Republic Hydrometeorological Institute of Serbia. (2012).
Operational Bulletin – Ice and Ice Drift on the Danube.
Belgrade, 22 February 2012.
[8] Soproni, L. (2020). Civil-Military Cooperation in Disaster
Response. Budapest: Zrínyi Miklós National Defence
University Press.
[9] Stevanović, S. (2018). Natural Disasters and Emergencies:
Planning and Response. Novi Sad: University of Novi
Sad, Faculty of Technical Sciences.
[10] United Nations Office for Disaster Risk Reduction
(UNDRR). (2021). Disaster Risk Reduction and Civil
Protection Cooperation Handbook.
[11] JVP "Vode Vojvodine". (2005). Ice and ice drift on the
Danube River (1991–2004). Novi Sad.