The word "declivity" is correct and usable in written English.
It is a noun that means a downward slope or a steep descent. You can use it to describe the incline of a hill or path, or to refer to a psychological or emotional decline. For example, "The hikers found it difficult to climb the steep declivity of the mountain."
Along the Deccan plateau there is a gradual eastward declivity, which dispenses its major river systems the Mahanadi, Godavari, Krishna, and Kaveri (Cauvery)—into the Bay of Bengal.
The London Basin is a wedge-shaped declivity bounded to the south by the chalk of North Downs, running north to south, and to the north by the chalk outcrop of the Chiltern Hills, running up in a northeasterly direction from the Goring Gap.
Toward the St .Lawrence it presents a bold and precipitous front; on the landward side and toward the St. Charles the declivity is more gradual.
You may wonder how a landscaped, 1.5 metre-deep declivity in a royal park can be anything but a stark physical fact.
What struck me at that moment was not how high we were but how low: a little earlier, we had flown within what seemed like hailing distance of the sheer east face of Longs Peak, and now, as Kunkel banked steeply to the right to give a better view of a stream at the bottom of a narrow valley, his wingtip appeared to pass just feet from the jagged declivity beneath.
"Ordinarily, you would expect something that deep to widen like a funnel" — resulting in an hourglass-shaped declivity, more like that of the Church Sink, which probably would have swallowed the entire structure.
A final topsoil cover is placed, compacted, and graded, and various forms of vegetation may be planted in order to reclaim otherwise useless land e.g., to fill declivities to levels convenient for building parks, golf courses, or other suitable public projects.
Mounds, curves, thickets, hollows and declivities sprawl in the sun.
In general, the mountains are of strong relief, being broken by deep valleys, sharp ridges, and steep declivities.
He was positing a landscape, wide and full, elevations and declivities, a map meant to reassure himself, too, Ann thought, charting something that would allay his own fears about his wife, his daughter, his life.
camera), swings back and forth within the curved cement tunnels and declivities of the park along with the kids, and the movie reaches a kind of nirvana of affectlessness.
