## Materials and Methods  
### Case Study  
As mentioned above, the VRMT-based approach was applied to the design of a VR-oriented training procedure for one of the meteo-hydrological risk divisions of the considered FR body, the Civil Protection HCP module. For the kind of tasks involved in this context, simulation-based training [28] can be easily regarded as the most suitable choice. The objective of the HCP module is to secure deluged areas by draining water from puddles or flooded buildings to avoid further damages and causalities. In particular, when the module is activated in an area along the sides of a river, the main goal is to eliminate puddles of water that can break the river bank. A standard set of training guidelines for this procedure was already in place [29], but they were heavily oriented to real-world training. Hence, they were quite limiting in the context of a deployment in a VR scenario. For instance, in real-world simulation scenarios, replicating a particular disaster event (location, weather conditions, etc.) is often unfeasible, but this becomes relatively easy when representing the event in a VE. The training experience was based on a hands-on exercise held in the city of Ivrea during a day of practical operations, when 20 participants from the Piedmont Region Civil Protection Unit and Coordination body of Civil Protection Volunteering simulated an intervention on a riverbank using actual equipment. Over five hours, a team of four researchers collected information and recorded videos to highlight the basic structure of the HCP procedure. The research team observed different participants, asked questions about the operations and possible variations and tried to use the equipment directly. Four main phases were identified to define the overall structure of the training. Since there were no well-defined roles in the exercise and each participant could perform every step of the procedure, the separation was based solely on time. A series of guidelines to be followed and equipment to be used in each phase was also outlined. The identified phases are reported below. 1. _Preparation of the operational field_: The team must inspect the flooded ground to decide the areas of water aspiration and delivery, as well as the positioning of the pump. The pump (Figure 1d) must be located near the aspiration (suction) area, avoiding if possible elevated regions in order not to affect the pumping capacity. Once the pump is placed, the team must delimit the operational field with poles and signaling tape in order to avoid external interference. If the delivery area is another river, a protective sheet (Figure 1c) must be positioned to avoid additional damage to its bank. During this phase and the following phases, each operator must wear adequate Personal Protective Equipment (PPE), such as gloves, a helmet, safety boots and a life west;
2. _Assembly of aspiration and delivery chains_: The team assembles the aspiration and delivery chains. For each chain, two operators must work together to handle the transportation of the tubes and operate safely. The aspiration chain is composed of semi-rigid tubes, starting from the pump up to the suction area, and by a final element (the filter, Figure 1a) that must be immersed in the puddle to be drained. The filter must be tied by a rope to be used later for its recovery. The operator that dips the filter must be secured to a second rope held by the other operator. Starting from the pump up to the delivery area, the delivery chain can be composed of rigid or semi-rigid tubes or foldable hoses (Figure 1b). The last element of this chain must be a rigid tube, placed on the protective sheet and secured to the ground using a rope and several pegs. All the tubes and hoses used in this phase have a male and a female endpoint.