Damage assessment
Investigation of damaged property and quantification of the value of losses. Monetary estimates usually depend on the cost of repairing the damage, which in turn depends on the adoption of particular techniques and components whose values are known.

Damage classification
Evaluation and recording of damage structures, facilities, or objects according to different categories.

Damage ratio
The cost of damage expressed as a ratio of the total value of the object damaged in a event. When referred to a given magnitude of event, this ratio represents vulnerability.

Danger (Threat)
The natural phenomenon that could lead to damage, described in terms of its geometry, mechanical and other characteristics. The danger can be an existing one (such as a creeping slope) or a potential one (such as a rockfall). The characterisation of a danger or threat does not include any forecasting.

Debris flow
A sediment transport of a mixture of fine material (sand, silt and clay), coarse material (gravel and boulders), with a variable quantity of water, that forms a muddy or a coarse slurry which move downvalley in a series of surge with steep fronts mostly made of large boulders. Three distinctive elements are distinguishable in a debris flow: the source area (triggering), the main track (runout), and the depositional toe (deposition). Triggering mechanisms of debris flows are frequently related to an increase in pore pressures due to high-intensity rainfall events or rapid snowmelt.

Decision-maker
The person or organizational unit who decides on a course of action in relation safety.

Declaration of disaster
Official issuance of a state of emergency upon the occurrence of a large-scale calamity, in order to activate measures aimed at the reduction of the disaster’s impact.

Disaster
A serious disruption of the functioning of a community or a society causing widespread human, material, economic or environmental losses which exceed the ability of the affected community or society to cope using its own resources. A disaster results from the combination of hazards, vulnerability, and insufficient capacity or measures to reduce the negative consequences of risk. Disaster is sometimes also used to describe a catastrophic situation in which the normal patterns of life (or eco-systems) have been disrupted and extraordinary, emergency interventions are required to save and preserve human lives and/or the environment. Disasters are frequently categorized according to their perceived causes and speed of impact.

Disaster insurance
Government-sponsored or private insurance policies for protection against economic losses resulting from disaster.

Disaster legislation
The body of laws and regulations that governs and designates responsibility for disaster management concerning the various phases of disaster.

Disaster management
A collective term encompassing all aspects of planning for and responding to disasters, including both pre- and post-disaster activities. It refers to the management of both the risks and the consequences of disasters.

Disaster mitigation
A collective term used to encompass all activities undertaken in anticipation of the occurrence of a potentially disastrous event, including preparedness and long-term risk reduction measures. The process of planning and implementing measures to reduce the risks associated with known natural and man-made hazards and to deal with disasters which do occur. Strategies and specific measures are designed on the basis of risk assessments and political decisions concerning the levels of risk which are considered to be acceptable and the resources to be allocated (by the national and sub-national authorities and external donors). Mitigation has been used by some institutions/ authors in a narrower sense, excluding preparedness.

Disaster preparedness
Measures that ensure the readiness and ability of a society to (a) forecast and take precautionary measures in advance of an imminent threat (in cases where advance warnings are possible), and (b) respond to and cope with the effects of a disaster by organizing and delivering timely and effective rescue, relief and other appropriate post-disaster assistance.

Disaster response
A sum of decisions and actions taken during and after disaster, including immediate relief, rehabilitation and reconstruction.

Drainage basin
(syn. catchments, river basin, watershed) Area having a common outlet for its runoff.

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