4. Water flows from low lying area to higher level without any external force. Ans:
Answers
unprecedented disasters hit the shores of northeast Japan because of a massive tsunami caused by a huge undersea earthquake. The strongest breakwater, 10 m high, was destroyed completely. The valuable lesson learned from this experience is that it is impossible to protect ourselves from such extraordinary natural disasters by mere construction of massive civil engineering structures such as seawalls and breakwaters. In addition, urban seawalls and dikes in many locations are suffering erosion damage, and their replacement or reinforcement is becoming necessary despite the prohibitive costs involved. When considering the inevitable rise in sea levels in the long term, the height of seawalls must also keep rising. However, proposing to replace or reinforce every seawall in Japan is unrealistic. Public funds are limited, whereas the costs associated with infrastructure replacement or reinforcement are unlimited.
Answer:
Impossible
Step-by-step explanation:
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