Соответствующая норма
Canada
Practice Relating to Rule 54. Attacks against Objects Indispensable to the Survival of the Civilian Population
Section C. Attacks in case of military necessity
Canada’s LOAC Manual (1999) states:
42. Where a party to a conflict is defending its national territory against invasion, it may destroy objects indispensable to the survival of the civilian population with intent to deny their use by the enemy if:
a. the objects are within national territory of and under the control of the party; and
b. their destruction is required by imperative military necessity.
43. Where such an extreme measure is taken, the destruction of objects indispensable to the survival of the civilian population should not leave the civilian population with such inadequate food or water as to cause its starvation or force its movement. 
Canada, The Law of Armed Conflict at the Operational and Tactical Level, Office of the Judge Advocate General, 1999, pp. 6-4 and 6-5, §§ 42 and 43; see also p. 4-8, § 82.
Canada’s LOAC Manual (2001) states in its chapter on targeting:
Where a party to a conflict is defending its national territory against invasion, it may attack objects indispensable to the survival of the civilian population if:
a. the objects are within national territory of and under the control of the party; and
b. an attack on the objects is required by imperative military necessity. 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 445.5.
In its chapter on land warfare, the manual states:
1. Where a party to a conflict is defending its national territory against invasion, it may destroy objects indispensable to the survival of the civilian population with intent to deny their use by the enemy if:
a. the objects are within national territory of and under the control of the party; and
b. their destruction is required by imperative military necessity.
2. Where such an extreme measure is taken, the destruction of objects indispensable to the survival of the civilian population should not leave the civilian population with such inadequate food or water as to cause its starvation or force its movement. 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 619.