Climate change impacts often play out in water, from droughts and water scarcity to flooding and slow-moving threats such as sea level rise.

On World Water Day, we've taken an on-the-ground look at efforts to manage the growing risks in two countries facing serious battles now and in coming years: Egypt and Yemen.

In Egypt, which will host the COP27 climate talks this year, stronger storms on the warmer Mediterranean Sea are pushing saltwater into the Nile Delta, the country's low-lying breadbasket, creating worsening flooding and leaving soils infertile.

The government is fighting back by building an innovative network of sand dikes to protect some of the worst hit area, cutting flood risk, local residents told our correspondent Menna Farouk.

But critics say barriers in one area push floodwaters to other areas - and without significant global emissions cuts, the adaptation push may not stand up to ever stronger storms and higher seas.

"The whole area should be protected, because the whole Nile Delta region is endangered by climate change, not just the lowlands," said Abbas Sharaky, of Cairo University.

In Yemen's port city of Aden, an ancient network of aqueducts once channeled floodwaters into storage cisterns for use in dry periods of the year, easing two water threats at once.

But the Tawila Cisterns, now thousands of years old, today barely function. In some places they are jammed with plastic bags and drink cans and in others makeshift shacks have clogged their channels.

"It's painful for me to look at it like this," Othman Abdulrahman, of Aden's antiquities department, told our correspondent Maya Gebeily.

As global warming fuels worsening floods and water shortages in Aden, restoring the system could be one way to build resilience - but money to make the needed changes is short, as basic humanitarian needs in the country eat up funding.

"Most of the donors think of food, medicine and water as the main three challenges that they need to tackle in this humanitarian context of protracted armed conflicts and war," admitted UN-Habitat's country head, Wael al-Shhab.

In some countries, an invisible source of water - that below ground - may be the surest way to manage growing water shortages.

About 99% of the planet's liquid fresh water is underground, according to this year's U.N. World Water Development Report. If managed correctly it could tide billions of people through coming shortages of drinking and irrigation water.

But because groundwater is hard to see, track and evaluate, it is often overused and undervalued, researchers said.

"There is an enormous opportunity if we can manage and exploit all this groundwater sustainably," said Richard Connor, editor of the new report published by UNESCO.

See you next week!

Laurie

Yemeni city looks to ancient past to survive climate change
As global warming fuels extreme weather in climate-vulnerable Yemen, restoring the Tawila Cisterns could help avert future disasters, officials say

Egypt erects sand barriers as rising sea swallows the Nile Delta
COP27 host hopes low-cost sand dikes can help hold back the Mediterranean Sea and protect the homes and incomes of people in the country's breadbasket

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'Invisible' solution to water shortages lies beneath our feet
With water scarcity set to worsen on a warming planet, a U.N. report calls for sustainable use of underground supplies, which account for 99% of freshwater

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