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Walls to protect Zanzibar resorts threaten fishing communities

By Mohamed Issa

UROA, Tanzania, March 21 (Thomson Reuters Foundation) - A
visitor to the Nungwi Peninsula in Unguja, one of Zanzibar's
twin islands, has their pick of luxury resorts, all promising
access to golden beaches.

But resort owners trying to protect those beaches from
coastal erosion, by erecting seawalls along the shore, are
coming under fire from residents and marine experts, who say the
trend destroys the environment and threatens the livelihoods of
local communities.

Built perpendicular or parallel to the beach, vertical
seawalls divert waves away from the beaches to slow the natural
erosion process. In some cases, concrete piles are placed in
front of the walls to help weaken the waves before they hit the
walls.

The problem, say environmentalists, is that while the
structures help keep resort beaches intact, the walls can speed
up erosion on other parts of the island by diverting the waves
to unprotected sections of the coast.

That can increase the intensity of other processes that
disrupt the local ecosystem, such as wave scouring - when waves
eat away at the base of structures such as cliffs - and
over-topping, when waves pass over reefs.

There are about 500 metres of vertical seawalls along the
beaches of Nungwi Peninsula, according to Peter Letitre, senior
project manager at the Netherlands-based Deltares water research
institute, with "more and more" being built all the time.

"The negative side is(they) accelerate the erosion by
washing away the sand at the foot of the wall," Letitre said in
an email interview.

DISAPPEARING DUNES, FLOODED GRAVES

Resort owners insist the seawalls are a matter of financial
survival. According to official figures, in 2014 Zanzibar's
islands had around 260 hotels - 20 of them boasting five stars.

Together they drew a large number of the 175,000 tourists
who visited the country that year - and the tourism sector
contributed between 25 and 27 percent to Zanzibar's gross
domestic product.

But the country's beaches are under constant threat from
erosion, a problem that is worsening as a result of sea level
rise linked to climate change, scientists say.

In the village of Uroa, on the eastern coast of Unguja,
villager Shaame Mcha Chambo told the Thomson Reuters Foundation
that the present beach line represents a loss of more than 40
metres of landmass "eaten by the encroaching sea" over the past
five decades.

Resorts on the islands are so concerned about the
encroaching sea that they feel they have no choice but to put up
seawalls, prioritizing protecting their property over the
uninterrupted sea views that their guests expect.

But when resorts build walls to stop their sand
disappearing, local communities can pay the price.

Chambo and two other Uroa villagers told Thomson Reuters
Foundation that the construction of a seawall at one resort
destroyed a major reef, while the erosion induced by the wall
has almost cleared the trees that provided natural protection
for the beach and has also indirectly contributed to the
submerging of a key offshore sand dune.

"Our fathers and relatives who eke out their living from
fishing used to stay at the dune as their transit point," they
said, referring to the practice of fishermen stopping on the
dunes for a few hours or even days to rest and plan future
fishing trips.

"Look, the dune is no more and the fishing patterns of the
people have been disrupted," he said.

Mariyama Ussi Khamis, a member of the Uroa executive
committee that helps run the village, told the Thomson Reuters
Foundation that in the five years since the lodge put up its
seawalls, enough unprotected land has been lost to cause the
village's coastal graveyard to succumb to seawater flooding.

"If the trend of erecting such seawalls is not reversed,"
she warned, the village of 3,050 people could see beach erosion
threaten its burial sites, a market place and about 15 homes
that sit along the shoreline.

Zanzibar's authorities seem to agree. In January, the
government's Department of Environment stated that the lodge's
20-to-30-metre-long vertical seawall was built against
regulations and has to be either removed or modified into
slanted walls.

Also called gradient walls or revetments, slanted walls are
better able to absorb the energy of the waves, which means less
water is diverted to other parts of the coast.

SOFT SOLUTIONS?

Letitre of Deltares warns that if the government does not
start considering large scale coastal management measures, in
the long term the beaches in front of and adjacent to the
seawalls will disappear.

Eventually, he said, there will be very little beach left
for the walls to protect.

If developers insist on building walls on their beaches, he
said, they should be slanted, and resorts should supplement them
with beach nourishment. The process entails "artificial
sand-re-circulation," where parts of the beach that have been
depleted are filled in with sand brought in from elsewhere.

"In general these 'soft' solutions are preferred over 'hard'
solutions (structures), since in general no erosive effects to
other parts of the coasts occur if soft solutions are applied,"
he said. He noted that 'soft solutions' are generally better
looking as well.

(Reporting by Mohamed Issa; editing by Jumana Farouky and
Laurie Goering :; Please credit the Thomson Reuters Foundation,
the charitable arm of Thomson Reuters, that covers humanitarian
news, climate change, women's rights, trafficking and property
rights. Visit http://news.trust.org/climate)

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