Munroe canals

The story of Munroe canals

The canals are not scenery arranged for visitors. They are the roads, and a good number of them are earthworks. Munroe Island is a cluster of low islets at the meeting of the Kallada river and the Ashtamudi backwater, and the water between them has always been how people moved, carried coir, went to school and got to church. A canoe trip here is a trip along somebody's street.

The boat matters more than anywhere else in Kerala — but be precise about which water you mean. The narrow inland village channels, the ones actually worth coming for, are too tight and too shallow for a shikara, let alone a houseboat. What fits is a small country canoe, poled or paddled rather than driven, and the difference is total: no engine noise, no wake, and a waterline low enough that the bank is at eye level. If an operator offers you a larger covered boat you will get the wide water and miss the thing itself. It does not follow that the whole network is canoe-only: the trunk cut, Puthanar, is fifty metres wide and carries ferries.

Go at first light. The canals hold mist until the sun clears the palms, kingfishers work the channels, and the day's first sounds are domestic rather than mechanical — someone washing, someone's radio, a paddle. By mid-morning the light is flat and the magic has gone. The 2.5-hour sunrise trip is the one to book.

The canal trip's own landmarks are mapped, and it is worth knowing their real names. The boating cluster sits at the island's eastern side, and within about two hundred metres of it are three named places: S Valavu, literally the S bend, where the channel doubles back on itself; Kandal Cave, kandal being Malayalam for mangrove, which is the tunnel section everyone photographs; and Ottakkandal, the lone mangrove. Coir retting frames stand in the shallows, prawn traps are checked, and in places the canal opens into small ponds where the water is completely still. None of it is staged, which also means none of it is guaranteed on a given morning.

Two sights commonly sold as part of the canal trip are not on it, and it is better to plan them separately than to be disappointed. The Perumon rail bridges stand about 1.8 km south on open Ashtamudi at the island's tip; the church known locally as the Dutch Church is about 2 km west on the far shore. Both are worth seeing. Neither is reachable through the narrow channels, and a trip that takes them in is a trip on the open water rather than a canal trip.

The overhanging vegetation is part of the experience and part of the navigation. Boatmen duck under branches, push off trunks and read water levels that change through the year — which channels are passable in February and which in September are not the same set. This is why the trip you get depends on the season as much as on the operator, and why the widely repeated advice to time your canoe to high tide is worth ignoring.

Legend & myth

Three things almost everyone believes about these canals are wrong, and all three have been measured. They are not a natural delta — the main one was dug. They are not silting up — they are getting deeper. And there is no point timing your canoe to the tide, because by the time the tide reaches here it has almost stopped being a tide.

Start with the digging, because it changes what you are looking at. The 2023 NCESS paper in Scientific Reports records that the trunk channel was cut in the 1820s to soften the monsoon floods and spread the river's silt onto the farmland in the south of the island. Its name is Puthanar, which is Malayalam for new river — the island's own language has been telling anyone who asked for two centuries. It is fifty metres wide. And the same paper notes that several of the islets exist because of that drainage network of natural and artificial streams: the cutting of the channels is part of why there are islands here at all. One honest caveat on the attribution — the work is credited to Colonel John Munro, who was Diwan of Travancore from about 1811 to 1814 and left in 1819, so an 1820s cut is after his own tenure. It was made on his design or by his successors; he did not stand over it.

The purpose is worth holding onto too. This was agricultural engineering — flood control and silt distribution — not a transport scheme and certainly not scenery. The tourism arrived a century and a half later.

Now the silting, which visitors ask about constantly because the mangrove tunnels look as though they are closing in. Measured bathymetry says the opposite: the river channel has deepened from 5–6 metres in the 1980s to about 14 metres now, driven by unregulated sand mining and by the sediment that the Thenmala reservoir upstream no longer sends down. The same paper's management recommendation refers in passing to the digging of boat channels, which is the detail that recasts the whole trip. The waterway you are paddling was cut two centuries ago and is dredged now. It is infrastructure at both ends of its life.

That deepening also explains why the flooding here is salt. Mining has dropped the riverbed below the base level of erosion, so dense seawater now sits trapped in the deeps instead of being flushed out, and the monsoon's fresh water no longer washes the surface soils clean. It is a plumbing failure rather than a sea-level story, and it is why houses fail.

Then the tide, which is the advice most worth discarding. The NCESS team put three tide gauges in and around the island and took readings at four locations across three seasons. What they found is that the inland tidal range is almost the same at spring tides as at neap; that the twice-daily component largely dies inside the estuary through friction and time lag; and, in their own words, that the flooding on Munroe Island is not related to the spring tide of the open ocean. There is no high-tide window to book. What decides which narrow channels a canoe can enter is the season's water level, and the hour that matters is dawn. Anyone telling you to go at high tide is repeating a line, not a measurement.

One last correction, and it is ours as much as anyone's. Munroe Island is sold as a timeless backwater idyll, and that framing is close to the opposite of what is happening here. The 2023 study measured about 14% of Munroe Thuruthu's total land area lost, with more than a quarter of the remainder under stress; the losses are very unevenly spread, with Cheriyakadavu at 46.95% against Peringalam at 11.78%. More than 500 households have been forced to vacate their homes. Kerala's first climate refugees is a phrase that has been used about this place, and it is not rhetorical.

The cause is the part travel writing almost never mentions, because it implicates another attraction in the same district. The Kallada river used to flood, and each flood laid down fresh sediment that rebuilt these low islets faster than the tide could take them away. Then the Kallada Irrigation Project and the dam at Thenmala put a barrier across the river's sediment supply. The floods stopped; the rebuilding stopped; the tide did not. Add uncontrolled sand mining on top, which has cut the river's own channel from 5–6 m deep in the 1980s to about 14 m today, and you have a landscape losing ground every year. The 2004 tsunami is commonly added to that list, but the satellite record dates the degradation to the 1980s and the peer-reviewed conclusion names only the dam and the mining.

So the two Kollam attractions are connected in a way neither page usually admits. The reservoir that makes Thenmala's eco-tourism possible is part of why the canals you are paddling through are flooding houses that were dry thirty years ago. We are not going to pretend that a canoe trip is a neutral act of appreciation while leaving that out.

One thing that is a genuine misconception rather than an omission: visitors sometimes read the flooding as picturesque — water in the yards, steps disappearing — and photograph it as atmosphere. It is damage. Houses here are abandoned because salt water gets into them. Read it correctly and the trip becomes a different and more serious thing.