Tanzania: Seawalls and mangroves help island-based farmers fight sea-rise due to climate change (Thomson Reuters Foundation)

| December 7, 2020

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Since the early 1990s, farmers in coastal Tanzania have been worrying about how rising sea levels are affecting their crops. On one coastal island, salt water has soaked soils. Banana farmers abandoned the crop, but been unable to make a living growing rice or cassava. But the building two concrete, 25-metre seawalls and replanting mangrove forests have changed everything. One farmer reports that, before the walls, seawater had reduced his banana yields from 150 bunches per harvest to 20. Since the wall, his yields have rebounded to 50 bunches per harvest.

A vibrant community of farmers calls Kisiwa Panza home. Today, this small island off the coast of Tanzania boasts banana trees with enough fruit to sell by the boatload. But only years earlier, the farmers of Kisiwa Panza saw a very different sight. 

According to Juma Ali Mati, chairman of a local environmental organization called JSEUMA, islanders first began to notice the impact of rising sea levels due to climate change in the early 1990s. 

For more than 25 years, the island has been soaked with salt water, killing farmers’ crops. Many people had to abandon their houses. When the banana trees died, farmers tried switching to rice and cassava—but nothing would grow in the salt-filled soil.

The construction of two concrete seawalls in 2017 changed everything. Built by the Tanzanian government with support from UN agencies and international environmental funds, the seawalls are 25 metres long.

Seawalls like these have been constructed at seven sites on Tanzania’s mainland and islands, allowing farmers to return to their homes and their fields.

With the waters tamed by the seawalls, islanders on Kisiwa Panza established another line of defense—mangrove forests. As they grow, mangroves protect the island against erosion and flooding due to sea-level rise while capturing carbon in the process.

Collecting and planting mangrove seeds has become a regular part of island life and residents are seeing the benefits. 

Before these defenses were put in place, Saida Ali Faki, a 35-year-old farmer, remembers a time when she could only grow enough to feed her eight children once a day. Now that floods no longer threaten her land, Ms. Faki plants maize and greens and expects a healthy harvest.

Mr. Mati from JSEUMA says that, before the walls were built, seawater had reduced his banana yields from 150 bunches per harvest to as few as 20. Since the walls went up, Mr. Mati has produced 50 bunches per harvest.

He says, “Since we have constructed this seawall, we can harvest again. Before, we were trying and getting nothing.”

But experts warn that seawalls may not be a permanent fix. The walls need to be regularly checked and maintained. And after the initial investment by aid organizations, some communities do not have the means to do so.

Seawalls have also been known to divert erosion and flooding to nearby areas that aren’t as well protected. It’s an issue that worries Ms. Faki.

As she watches her children plant more mangrove seeds, Ms. Faki says the islanders are starting to make progress in the fight against rising sea-levels—but they still have a long way to go.

She says, “If the other areas that have the same problem don’t get walls and people don’t plant mangroves, the problem … will continue.”

Photo: Residents of the island of Kisiwa Panza, in the Tanzanian archipelago, walk toward mangrove forests, April 26, 2018. Thomson Reuters Foundation/Hannah McNeish

This story was adapted from an article originally written by Hannah McNeish and published by the Thomson Reuters Foundation titled, “Seawalls and forests aim to save the living – and dead – in Tanzania.” To read the full story, go to: https://news.trust.org/item/20181207095617-2i44d/