The average gestation period for rabbits is 31 days; however, it can vary from 29 to 35 days. Does should be pregnancy-checked 14 days after mating. If not pregnant, they can be re-bred immediately.
Buttresses and an arch of the Roselend Dam in France. A buttress dam or hollow dam is a dam with a solid, water-tight upstream side that is supported at intervals on the downstream side by a series of buttresses or supports.The dam wall may be straight or curved. Most buttress dams are made of reinforced concrete and are heavy, pushing the dam into the ground.ater pushes against the dam, but the buttresses are inflexible and prevent the dam from falling over. Buttress or hollow gravity dams were originally built to retain water for irrigation or mining in areas of scarce or expensive resources but cheap labour.
How Dams Work. A typical dam is a wall of solid material built across a river to block the flow of the river thus storing water in the lake that will form upstream of the dam as water continues to flow from the river upstream of the dam.The main purpose of most dams is to create a permanent reservoir of water for use at a later time.s well as being watertight a dam must also be stable ie the dam wall must have sufficient strength to firstly, stand permanently under its own weight especially when at least part of the dam wall is saturated with water and secondly, resist the water pressure in the lake upstream of the dam.