obviate

二宮尊徳は幕府にも認められ、利根川下流の沼地干拓計画にも参画します。
Once he was appointed by his government to report upon some possible plans of draining the great marshes on the lower course of the river Tone. If accompplished, such an enterprise would serve triple purposes of inestimable public benefit: it would recover thousands of acres of fertile land from the shallow and miasmatic marsh; would drain off surplus water in time of flood, and obviate much of damage yearly done in those quarters; and would afford a new and short passage between the river and the bay of Yedo.
この "obviate" は文脈からすると「防ぐ」の意味だと思いますが、知らない単語なので辞書を見ます。
・Macmillan Dictionary: to get rid of something such as a need or a problem: The use of this equipment should obviate the problem.
・Vocabulary.com: To obviate means to eliminate the need for something or to prevent something from happening. If you want to obviate the possibility of a roach infestation, clean your kitchen regularly.
The prefix ob means "to go against." That makes sense when you look at the words obstruct and obstacle, but how about obstetrics? Why does the name of the branch of medicine dealing with birth have the same root as words that mean "stop" or "get in the way"? Because a midwife stands opposite to, or against, the woman giving birth.
"obviate" は「防ぐ」ではなく、「取り除く」ことにより結果として「防ぐ」ことになったのですね。