In Wilmington, she and her husband, an electronics specialist, moved into a ranch-style house a short drive from her office, settling into a life of comfortable routine.

Ask Mrs. Chen about her home or hobbies and you may get a word or two. Ask her about water flow or the Ohio River and she will talk for hours. Some 25 million people live along the Ohio River basin, which runs more than 900 miles from Pittsburgh to Cairo, Ill., where it joins the Mississippi River. Along the way, it flows through locks and dams operated by the United States Army Corps of Engineers. Mrs. Chen developed a forecasting model for predicting floods along the Ohio and its tributaries. The model involves constant data-gathering about water levels and rainfall, as well as how dam and lock operators respond to water flow.

Mrs. Chen was known to be tenacious in her pursuit of data for her predictions. She developed carpal-tunnel syndrome in her right hand from eight years of repetitive mouse clicks. Thomas Adams, who hired Mrs. Chen at the National Weather Service in 2007, said her fascination with data made her perfect for the job.

“Sherry is and was dedicated to getting the details right — and that matters significantly,” Mr. Adams said, noting that one inch of water could make the difference between a levee holding or failing.

Mrs. Chen would return to Beijing every year to visit her parents, which is how her troubles began. During her 2012 trip, a nephew said that his future father-in-law was in a payment dispute with provincial officials over a water pipeline.

The nephew knew that one of Mrs. Chen’s former hydrology classmates, Jiao Yong, had become vice minister of China’s Ministry of Water Resources, which oversees much of China’s water infrastructure. As Mrs. Chen tells it, her nephew asked her to reach out to Mr. Jiao, hoping he might be able to help his future wife’s father. Mrs. Chen said she was reluctant to do so since she had not seen Mr. Jiao in many years, but ultimately contacted him.

Mr. Jiao’s secretary set up a 15-minute chat in his office in downtown Beijing, and Mr. Jiao said he would try to intercede. As their conversation wound down, he also mentioned that he was in the process of funding repairs for China’s aging reservoir systems and was curious how such projects were funded in the United States.