This was one of the conclusions reached by a task force led by Lord Robert Mair, emeritus professor of civil engineering at the University of Cambridge, to examine the management of railway cuttings and embankments.
The report was published alongside a study into the impact of heavy rainfall on the railway.
A total of more than 50 safety recommendations were made to Network Rail by the inquiries.
Driver Brett McCullough, 45, conductor Donald Dinnie, 58, and passenger Christopher Stuchbury, 62, died when the 6.38am Aberdeen to Glasgow Queen Street train crashed into a landslide across the tracks near Stonehaven, Aberdeenshire, on August 12 last year following heavy rain.
Six other people were injured.
Network Rail's interim report on the crash found that the train "struck a pile of washed-out rock and gravel before derailing".
Lord Mair's report stated that "shortfalls in the earthwork examination and risk evaluation system need to be addressed", with "significant investment" required to update the Government-owned company's monitoring and surveillance methods.
"More regular and frequent use" should be made of helicopters and drones to identify problems, his task force found.
Martin Frobisher, Network Rail's safety and engineering director, said: "It is clear that extreme weather presents a significant challenge to the way we safely and reliably manage railway infrastructure.
"We established two independent, expert task forces led by world-class specialists to investigate the problems we face and, crucially, to guide us as we make substantial improvements.
"We will carefully consider every single recommendation and develop a science-backed improvement plan, to target available money and technology in the best possible way. This is a real breakthrough."
Transport Secretary Grant Shapps said: "These findings will inform our work as we push ahead with measures to make our railway more resilient in future, and less vulnerable to sudden tragedies like that near Stonehaven."
A spokesman for train drivers' union Aslef said: "The Government has to provide Network Rail with the funds so it can carry out the work that is needed to maintain our rail infrastructure so that passengers, and crew, can be confident of the safety of our railway."