How to measure land reclamation progress from satellite imagery

A reclamation job doesn't announce itself. The contractor's placement schedule says one thing, the permit conditions say another, and the only way to know what's actually been filled is to count trucks at the gate or wait for the next progress report to land. For an analyst tracking berth construction and reclamation across more than one port, that's slow. Satellite imagery is the one data source you can pull on a schedule you control, rather than one the contractor controls.

What you're actually measuring

Reclamation progress isn't one number. It's a handful of distinct things, and each shows up differently in an image:

Area of fill placed: acres reclaimed to date against the permitted footprint
Berth line extension: linear meters of revetment or quay wall built out
Spoil ground growth: where dredged material is being stockpiled or disposed, often well away from the main fill
Shoreline advance: how far the new land has pushed past the original coastline

Fill placement reads as a lighter, disturbed surface pushing out from the bund wall. Berth line extension is a hard, straight edge growing along the waterline. Spoil ground growth tends to show up as a mounded, textured patch some distance from the active reclamation, sometimes on the far side of the harbor entirely.

A single image vs. a sequence

One satellite pass tells you the state of a site on one day. That confirms a rumor well enough, but it doesn't give you a rate. Measuring progress means comparing at least two passes separated by a known interval, and ideally a run of them at even spacing so growth is comparable quarter to quarter.

The workflow is straightforward:

Pull an image of the site from roughly the same time last quarter.
Pull the current image, matched sensor and look angle where possible.
Overlay the reclaimed footprint from each pass and measure the area difference.
Do the same for berth line length and spoil ground extent.
Log the delta against the permitted limit and the contractor's stated schedule, if you have one.

At 0.5-2 m resolution you can trace the edge of a bund wall or revetment by eye and get a usable area measurement. You won't pick up individual trucks or plant on site, but you don't need to. You need the footprint, and the footprint is what moves quarter over quarter.

Why quarterly cadence beats ad hoc checks

Reclamation rarely jumps in dramatic steps. A three-month interval is usually enough to show a real change without burying the analyst in near-identical images that show nothing new. Pulling imagery ad hoc, whenever a report lands or a rumor surfaces, means every comparison starts from a different baseline and a different time gap. The growth-rate figures stop being comparable across sites, and eventually across your own notes from six months back. Locking in one cadence, and keeping the before/after pair on that same cadence every time, is what makes a quarter-over-quarter number mean something.

Doing this without a site visit

A site visit confirms what's on the ground, but it takes time to arrange, costs travel budget, and only tells you about the day someone stood there. For a portfolio spread across a coastline, or across borders, that doesn't scale past a handful of projects a year. A side-by-side of two quarterly images gets you most of the same information: how much new area has been filled, whether the berth line moved, where the spoil is piling up, all from a desk.

That's the comparison Port Monitoring is built around. It runs each new quarterly pass against the last and hands back a change layer, reclaimed area added, berth line extended, spoil ground growth, exported as GeoJSON or a map layer with the before/after pair attached.

If a reclamation project on your list is due for its next quarterly check, that's worth a look before the contractor's next report lands.