voice-over: this is bbc news. we will have the headlines for you at the top of the hour, which is straight after this programme. this is arguably one of the most important rivers in the world. the mekong sustains tens of millions of lives. for thousands of years, it has filled fishermen�*s nets and nourished rice fields right across south—east asia and china. but there are increasing signs that this ecosystem — one of the richest ecosystems on the planet — is being strangled. the mekong is under an onslaught of dam building, intensifying climate change

and sand mining. but there is some hope. join us as we head downstream in cambodia and meet the communities having to adapt to the changing nature of this river... translation: there will be no fish for the next generation. . ..and those trying desperately to save it. translation: when i see this, it makes me worry about mekong's fate. mi lives in a world of water that was once predictable, reliable, renowned

for an abundance of fish. but in recent years, he and thousands like him have been asking, "where are they?" this is the tonle sap, south—east asia's largest freshwater lake. fish caught by communities here feed millions across cambodia. translation: these past few years, - there is less and less water and fewer and fewer fish. i didn't expect to get a lot of fish because when i felt the weight of the net, it was very light. i felt right around it and i just couldn't feel many fish.

if they were there, i would feel them splashing around. this is not the catch mi and his family need. this is all they have to eat for four or five days. so how difficult is it for you to earn a living byjust fishing? translation: when we were just married and we had no children, l it was ok. but now, we have children, and every day, i need to send them to school. every morning, i need around $5 to pay for school. and these days, i have no income. it's taken four or five days, and that's all i get.

i have no fish to sell. mi believes the lake is slowly running dry. this year, water levels are far lower than normal, threatening his very existence. like hundreds of others, he has built a home on the water. he has no land. his wife goes through the meagre catch, discarding the snails and crabs. these bamboo houses on floating oil drums are moved with the ebb and flow of the lake, from wet season to dry. it's been this way for generations, but mi wants this way of life to end with him.

translation: my children, i want them to study - and finish grade 12, and i will send them to learn a language and find a job. i don't want them to live here on the lake. it is hard. but what can i do? no matter how hard it is to earn, i have to try so my children can graduate. more fish are caught in the tonle sap than anywhere else in the world. three—quarters of the protein cambodians eat is fish. without these stocks, millions could starve. a recent study suggests that catch numbers over the last 20 years have fallen by more than 80%.

a population boom has led to overfishing. but there are other problems, too. this year has been the hottest on record, bringing droughts in the dry season, which could be affecting the very nature of the lake. this lake is often called the beating heart of the mekong because it has a pulse. twice a year, something extraordinary happens. in wet season, monsoon rains fill the mekong, pushing water up the tonle sap river and into this lake, expanding it to six times its size and, crucially, bringing with it migrating fish. in the dry season, the opposite happens. the water is pushed back into the mekong and down towards vietnam. but in the last few years, there are signs that this pulse is weakening.

to find out why, we need to go to the source of the mekong. this flowing lifeline descends from the glaciers of the himalayas. since the 1990s, some have eyed it as a potentially powerful energy resource. china has built 11 dams on the mainstream. laos has two. dozens more are planned. this hydropower is valued at around $4 billion a year. experts who monitor water levels in the dams are worried. climate change and dams are working together to deliver a death of 1,000 cuts to the mekong system. we know this because we're seeing, through our work on the mekong dam monitor and the work of many others, that rainfall that typically would fall during the wet season is much lower than normal. but at the same time, upstream dams are restricting water during that wet season.

so that's bringing the pulse and bringing riverflows down much lower than they need to be. together, climate impacts and dam restrictions are changing the way that the mekong flows, much for the worse. the don sahong dam on the laos border was built despite concerns raised by cambodia, thailand and vietnam. in a bid to pull itself out of an economic crisis, laos aims to become the battery of south—east asia, provide this region with much—needed sources of green energy and turn them away from coal. the problem is researchers believe that these numerous dams are fundamentally changing the function of this river. here, too, there are reports of declining fish stocks. river levels rise and fall outside of wet and dry season, altered when water is released from the dam.

studies suggest that the dams are also holding back the lifeblood of the mekong — its sediment. now, this water might look muddy, or even dirty to you, but actually it's full of sediment. these are nutrients that the water carries on itsjourney all the way through china. and it's that sediment that's essential for both the fish and for rice farming. if action is not taken now, the amount of sediment reaching the river basin could be reduced by more than 90%, according to the mekong river commission. dam building may restrict the movement of the river, but it forces the movement of people. translation: this new village is nothing like our old village. many aspects of our lives have changed.

back then, we were happy. there was enough food to eat, unlike now. 18—year—old bopha and her daughter are part of a two—millennia—old indigenous tribe. limited electricity in this new village comes from a generator, not the nearby hydroelectric dam... ..a dam that forced them and thousands of others to leave their ancestral home. bopha once lived in kbal romeas, a self—sufficient village community next to the srepok river, which flows into the mekong. the creation of a dam and reservoir flooded large areas, destroying their homes. translation: i was scared and sad to lose our village i because our village used to be

beautiful and leafy. there were all kinds of plants and veggies and fruits everywhere, enough to eat. it's an hour's boat ride to bopha's former village, through a graveyard of trees stripped of life by the flood. this house, they moved to the new village. that, the pagoda, school, and that is my house there. the flood dispersed a people with intimate attachments to this land. some accepted compensation or resettlement fees. others, like bopha, have built homes close by. she's one of millions of people who've been displaced by dams built across china and south—east asia. translation: 10096, - i don't think we can forget our birth village

because our ancestors gave life to us here. we remember them here. even their ghosts don't want to leave this village. this home is my soul. i'm deeply sad about losing this village because this is where i used to run around and be filled with joy. seeing it looking like this, it hurts. i can't help all these trees. i can only help myself. here's the old graveyard. you can usually see the old grave pillars, but it's all under the water now. she's searching this spiritual site for her grandfather's grave

but settles on giving her offerings wherever she can. prays bopha still tries to connect with her past, even after the dam washed away 2,000 years of tradition. hydropower that hopes to modernise her country has altered the course of her life. the lower sesan dam is one of asia's widest. the cambodian government says it is living up to its potential and provides 20% of the country's electricity needs. some researchers doubt this figure. the government also argues that the reservoirs are useful for irrigation and can help with water supplies in dry season.

these benefits, however, come at a cost. it's now up to the next generation to find ways to adapt to man—made interventions in the mekong's course. these young people, most of them teenagers, are sacrificing their sleep for the sake of their river. they're on the hunt for those who would exploit the mekong's remaining bounty. the team navigate in the dark, only turning on their torches to scour the banks for fishermen who might be using dynamite or electrocution to illegally kill hundreds of fish. translation: my name

is u meta. _ i'm 19 years old. i choose to help patrol this river because i love our natural flooded forests. my dad is my role model. he's patrolled the river for 13 years. i thought to myself, "the least i can do is help out "and be part of these small patrols as a youth". this work can make the patrollers unpopular. at night, fishermen often turn to illegal methods when they're desperate to earn money. if we come across an illegal activity, we have to drive the boat fast to chase them and sometimes, ifear that the boat will capsize. i was also worried that some of them will be armed. what would i do? so, it was scary at first. but it's important to guard

the river now in wet season. this will give time for the fish to spawn and grow. at first light, the patrol head home. li meta also spends time with villagers, trying to help them understand that their river is in crisis. because i love our natural resources in the flooded forest, i want to preserve this river for the next generation. i also want to help tell local people that our flooded forest sites are at risk because of illegal fishing. if those illegal fishing activities increase, villagers won't be able to get enough fish for them and their family. there will be no fish for the next generation, as more and more fish breeds become extinct. when i was young, whenever i went to the river with my dad, ifelt so happy, seeing the wide river. now, when i look at the river, it makes me feel like i want to protect it because it is almost gone.

especially the fish. they are the most at risk. the balance of wet and dry season is crucial for these flooded forests. without it, they die, and so do the fish breeding grounds. the new river guardians can't control climate change or dam building, but they do hope to conserve fish numbers. there are signs that life is returning. the world wildlife fund has helped create a safe haven for a pod of endangered irrawaddy river dolphins. this area is their last refuge. the numbers of newborn calves are rising.

researchers hope this indicates that the health of the river is being restored. further downstream, however, the mekong has other gifts to give. sand. river sand is much more coarse than the sand you'd find on a beach, which makes it idealfor concrete and construction. large barges dredge it from the river to supply developing south—east asian cities. 25—year—old kunthea was jailed for more than a year for organising a protest to preserve the mekong. translation: when i see this, it makes me worry i about the mekong's fate and its impact on the cambodian people as a whole.

does your mother, does your family, worry about you? yes, she's worried, but she's never told me to stop doing what i do. at first, of course, a parent will always worry about their child. however, i try to tell her that this problem on the mekong is a problem for all of us. the mekong's sediment—rich sand has played a key part in the rapid urbanisation and transformation of phnom penh. kunthea organised a one—woman march after hearing that the government was using it to fill in lakes and rivers and create new land for real estate and shopping malls. before i was arrested, i announced that i would wear all white and would walk from hun sen, our prime minister's house. the reason i wanted to wear white was because in cambodia, the tradition of wearing white represents mourning and i wanted to mourn nearly 20

lakes that have been filled. each of these barges can hold enough sand to fill an olympic—sized swimming pool. the government has long been accused of profiting from plundering the country's natural resources, which it denies. it says it supports environmental activism but claims the group mother nature encourages social unrest. kunthea continues to post videos of her investigations online and she says the risks are worth it. i want to do something for positive change. i don't want to see this continue to happen to cambodia, to cambodian people, and to our next generation ever again. when i feel tired sometimes, once i meet people, young people from the community always encourage me and that motivates me to keep going.

around 60 million tonnes of sand a year is dredged from the mekong, according to research by newcastle university. this is unsustainable, they add. where i'm standing was actually once the river but they've not just used this sand to create a new island, they've built office blocks, condos, skyscrapers. even the windows will need sand. but cambodia is not alone in its insatiable desire for sand. it is the world's most mined mineral. the problem here is they are dredging at an already fragile ecosystem that scientists fear is on the edge of irreversible collapse. the mekong is called "the mother of water" in the many languages spoken along its banks.

for centuries, through war and peace, she has been a one true constant. it may never be that way again. human development, coupled with a changing climate, will continue to alter the river's course and alter lives. but its flow has not yet been stilled. environmentalists believe that the mighty can once again be restored to the mekong. its fate may depend on the resilience of the people it supports and how far they are willing to go to defend it. hello there. let's take a look at

the weather for the week ahead. now, new year's eve, still plenty of blustery showers across the uk, particularly towards the west, where we saw some heavy downpours. beautiful clouds but some hail, some thunder and some very pretty rainbows with some sunny spells, too. some blustery winds towards the south—west in particular, along the south coast of england and through the south coast of wales from this deep area of low pressure gradually pushing eastwards with blustery showers swirling around it. on monday, we've got a quieter day of weather for new year's day. many of us will stay dry but there are also going to be some heavy downpours of rain again in the south, so into the new year, it will stay pretty unsettled, it will be wet and windy at times, especially towards the south. and then, into next weekend, it is going to turn drier, more settled but also start to feel colder once more. so, as we head through the day on monday, it is a dry early start. there will be a lot of sunshine around as well. some showers out towards western areas

of scotland. clouding over across wales and south west england through the late morning with the rain arriving by the end of the day but the sunshine lasting longest probably for northern england, east anglia, northern ireland and for much of scotland, where there will be plenty of dry weather around. temperatures slipping a little. mildest underneath that cloud and rain towards the south—west. still rather blustery conditions towards the south coast. and as we head through monday evening, then that rain pushes further northwards and eastwards across already pretty saturated ground. do keep an eye on the bbc weather website for all the flood warnings in place. more rainjust waiting in the wings as we head through tuesday morning. again, mostly across the south of england and wales. so, if we just take a look in a bit more detail, there's our rain just feeding into south—eastern areas of scotland with a brisk south—easterly wind. a bit wintry over the hills of aberdeenshire. more rain pushing across england and wales, gradually clearing further northwards as we head into the afternoon, so it will be drying out here. but, again, some blustery gusts of wind, probably largely dry

across much of northern england throughout the day and for many parts of western scotland, too. temperatures mild in the south. again, cooler across northern ireland and scotland. and as we head through wednesday, that weather turns a little more showery towards parts of england and wales. a lot of dry weather across eastern areas of northern ireland and for northern england, too, again. more rainjust feeding through on that brisk south—easterly wind across parts of aberdeenshire. again, possibly a bit wintry over the hills. temperature 7—11 degrees celsius north to south. on thursday, it'll be another day of showers but also some brighter spells — a bit of sunshine around for many. here's the outlook for our capital cities as we head through thursday and friday. a bit more rain in the forecast for many on friday and the temperatures will start to slip. and things are certainly set to change as we head through into next weekend with high pressure starting to slip southwards from iceland. it becomes quite firmly established. we'll be on the cooler side of the jet by then.

colder—feeling air dropping temperature with a north—easterly wind, so the focus of the showers as we head through the weekend and probably beyond that, too, will tend to be out towards the east and, again, some of those could turn out to be a little wintry in nature. so, all change. any showers will tend to be towards the east. drier, colderweather by the time we get to next weekend. northerly winds with some overnight frosts but possibly still a little blustery towards the south coast. bye—bye for now.

live from washington, this is bbc news. the queen of denmark stuns with the announcement of her abdication after 52 years on the throne during her new year address. the us military destroys three boats after another attack by iran—backed houthi rebels on a freight ship in the southern red sea. russia steps up its strikes on ukraine as president zelensky vows not to make any concessions in the year to come. big ben bongs and the new year has begun in many parts of the world. we look at some of the most jaw—dropping new year's eve celebrations.

hello. i'm carl nasman. the world's only reigning queen says she's stepping down from the thrown. denmark's queen margrethe ii made the surprise announcement in her new year address. the 83—year—old will formally step down onjanuary iii — that's 52 years to the day since she came to power in 1972. her son, crown prince frederik, will take her place as king of denmark, and head of the state in the country. for more on the queen's reign and what's next, the bbc�*s naomi choy smith sent this report. a surprise announcement, live on national television, during queen margrethe�*s traditional new year's address. translation: on the 14th of january 2024, _ 52 years after succeeding my beloved father, i will step down as the queen of denmark. the 83—year—old danish queen

said time had taken its toll on her health and she made the decision to abdicate