Mr Q
JF-Expert Member
- Aug 16, 2012
- 18,046
- 38,598
Kwahiyo aache tu? Kwani hao sivili injiniaz wanafanya kazi gani kwanini wao wasishauri mapema?
Kwahiyo aache tu? Kwani hao sivili injiniaz wanafanya kazi gani kwanini wao wasishauri mapema?Jifunzeni kua na akili, siyo mpaka majanga yatokee nchi zingine ndiyo mnajifanya na ninyi mnaweza kufikiri kumbe ni Bure tu, hiki ulichosema ni sahihi kabisa, lakini ulikua wapi kuishauri serikali
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Gumzo kubwa linaloendelea ulimwenguni baada ya mafuriko ya maji Libya baada ya mabwawa mawili kupasuka, kwa sababu ya uchakavu na kutofanyiwa maintenance na uborejashi. Je, hili linaweza kutokea kwetu Tanzania, tukijua kuwa tuna mabwawa ya muda mrefu sana kama Kidatu na Hale?
Ni wakati fika haya mabwawa mawili niliyoyataja yakipasuka watu wengi sana watadhurika ki hali na mali.
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Which of the world’s hundreds of thousands of ageing dams will be the next to burst?
A general view of the city of Derna is seen on September 12, 2023. For years, experts warned that floods pose significant danger to dams protecting nearly 90,000 people in northeast of Libya, repeatedly calling for immediate maintenance to the two structures outside the city of Derna. But successive governments in the divided and chaos-stricken North African nation did not heed their advice. — AP file
The collapse of two dams in Libya, unleashing torrential floodwaters that left at least 3,000 people dead and over 4,200 still missing, was both predicted and preventable. And they won’t be the last big dams to collapse unless we remove and repair some of the aging and obsolete structures that are long past their expiration date.
Like many dams around the world, the Wadi Derna dams in Libya were built in the 1970s during the era of peak global dam construction, when 1,000 large dams were installed each year. Now most of these dams are reaching the end of their life spans.
Details are still emerging, but the Libya dam collapses appear to have been caused by poor maintenance, and by poor monitoring of reservoirs that were overwhelmed by a huge rainstorm. Critical warnings were issued last year about the dams’ deteriorated state and the repairs needed to avert such a scenario, yet no action was taken.
Similar disasters are waiting to happen around the world. The biggest danger is in India and China, where the 28,000 large dams built in the mid-20th century are now nearing obsolescence. Mullaperiyar Dam in Kerala, India, is over 100 years old, visibly damaged and located in a region prone to earthquakes. Its collapse would harm 3.5 million people downstream.
In the United States, the second most prolific dam-builder after China, the average age of dams is 65 years old and an estimated 2,200 structures are at high risk of collapse. The recent infrastructure law directs $3 billion into maintaining some of them, but there are still thousands of dams the federal government is not responsible for, and it will cost an estimated $76 billion to fix them.
The risks from ageing dams are of particular concern in the face of climate change. Dams are designed to withstand worst-case conditions as they can be imagined at the time of construction. But what were once considered once-in-a-century weather events have begun occurring with increasing regularity, putting dams at great risk of either failure or a significant weakening of their integrity.
Before the disaster in Libya, extreme weather worsened by climate change was already taking its toll on these structures. Heavy rainfall damaged California’s ageing Oroville Dam in 2017, prompting mass evacuations amid fears of major uncontrolled releases. A piece of a Himalayan glacier destroyed one dam and damaged another in northern India in 2021, killing dozens of people. Glaciers melting rapidly as a result of warming are now a major safety hazard to dams and communities living downstream.
The default approach has been to repair ageing dams where needed, monitor reservoir levels and try to anticipate rainfall and increased flows from upstream. Take the Kariba Dam on the Zambezi River in southern Africa, which is undergoing extensive repairs to prevent its collapse after the riverbed below it was found to be severely weakened. At a cost of $300 million, these repairs are required simply to keep the dam standing on a river where hydroelectricity production has already plummeted from drought. Projects like these essentially paper over the cracks, and are often significantly more expensive in the long run than removing dams that are already obsolete.
While some ageing dams still supply drinking water and help farmers irrigate their fields, many that were built for hydropower only generate a fraction of the electricity they once did as sediment accumulates behind their walls. Deepening drought linked to climate change has also crippled hydropower generation all over the world, leading to energy rationing and blackouts in the United States, China and Brazil.
The fact that it’s increasingly difficult to justify many dams’ existence is one reason there is a growing movement, often led by Indigenous peoples and other marginalised populations, to remove them. Most notably, the removal of four dams on the Klamath River along the Oregon-California border, set to be completed next year, will be the largest such effort in history.
Dam removal and river restoration are also picking up speed in Europe. Its rivers are among the most highly fragmented in the world, and have seen large declines in freshwater biodiversity. The River Meuse restoration project in the Netherlands, which includes restoring its floodplains to address flooding and drought, is expected to reduce extreme inundation from once in a century to once every 250 years.
The tragic dam disaster in Libya is a warning siren for other ageing dams around the world. Our best tool is removing them altogether. We must start using it much more often.
(Josh Klemm and Isabella Winkler are co-directors of International Rivers, a group that advocates for healthy rivers and the rights of river communities.)
This article originally appeared in The New York Times.
Huyo ana hati miliki ya nchi mkuuMakamba akamatwe anyongwe na kutupwa porini aliwe na fisi
Acha kumwandama Rais wako anayepikwaHakuna cha kuomba hapa tumeyataka wenyewe.
Makamba wamemtoa baada ya kuona haya kumwondolea aibu ya karne...
Tunaposema Makamba anabebwa mtuelewe. Hajatumbliwa ila kasafishwa
CCM haijengi hilo bwawa. Bwawa linajengwa na wataalamu makampuni ya nje. Hizo nyufa ni za kupumulia pale maji yakizidi kimo.Ila CCM huwa inaona watu wote ni wapumbavu.
Baada ya kusikia Libya bwawa limepasuka na yenyewe yakapata wazo la kuhalalisha ubaradhuli wao Tanesco kwa kusingizia bwawa jipya kabisa lina nyufa.
Ilivyo mijinga ilishindwa kutafakari kuwa bwawa lao ni jipya hivyo uwepo wa hizo nyufa ni kujidhalilisha wenyewe kuwa hawakuwa makini na ujenzi.
Mwacheni aandaliwe anafaa sana kuwa rais wa nchi. Hakuna zaidi yake mpaka sasa. Bisha nikutumie ng'e wakudunge sumu.Huyo ana hati miliki ya nchi mkuu
... ila tukiwa wakweli wa nafsi zetu; Makamaba anahusika vipi na ubovu ulioonekana kwenye bwana? Maskini ya Mungu mkataba uliingiwa hana hili wala lile; ujenzi unaanza hayupo serikalini; kaja kusukumiziwa dakika za mwisho ujenzi wa concrete ni 100% umekamilika! Hata kama ni chuki, this is too much.Hakuna cha kuomba hapa tumeyataka wenyewe.
Makamba wamemtoa baada ya kuona haya kumwondolea aibu ya karne...
Tunaposema Makamba anabebwa mtuelewe. Hajatumbliwa ila kasafishwa
Kwa hiyo nyumba yako nayo ni bwawa? Hizi ndiyo akili za KimagufuliKwani bwawa ni Nini kama sio jengo
Makamba akamatwe anyongwe na kutupwa porini aliwe na fisi
Bwawa ni jina tu lakini yote ni jengo kanuni zile zile.Kwa hiyo nyumba yako nayo ni bwawa? Hizi ndiyo akili za Kimagufuli
Kwani Makamba ndio mkandarasi wa hilo bwawa!? Halafu wakati akipewa mamlaka siamekuta mradi umeshaanza kutekekelezwa muda mrefu!?Hakuna cha kuomba hapa tumeyataka wenyewe.
Makamba wamemtoa baada ya kuona haya kumwondolea aibu ya karne...
Tunaposema Makamba anabebwa mtuelewe. Hajatumbliwa ila kasafishwa
Achana nao hawa,ukoo wa yule jini mla damu za watuKwani Makamba ndio mkandarasi wa hilo bwawa!? Halafu wakati akipewa mamlaka siamekuta mradi umeshaanza kutekekelezwa muda mrefu!?
Kufa kufaanaGumzo kubwa linaloendelea ulimwenguni baada ya mafuriko ya maji Libya baada ya mabwawa mawili kupasuka, kwa sababu ya uchakavu na kutofanyiwa maintenance na uborejashi. Je, hili linaweza kutokea kwetu Tanzania, tukijua kuwa tuna mabwawa ya muda mrefu sana kama Kidatu na Hale?
Ni wakati fika haya mabwawa mawili niliyoyataja yakipasuka watu wengi sana watadhurika ki hali na mali.
=========
Which of the world’s hundreds of thousands of ageing dams will be the next to burst?
A general view of the city of Derna is seen on September 12, 2023. For years, experts warned that floods pose significant danger to dams protecting nearly 90,000 people in northeast of Libya, repeatedly calling for immediate maintenance to the two structures outside the city of Derna. But successive governments in the divided and chaos-stricken North African nation did not heed their advice. — AP file
The collapse of two dams in Libya, unleashing torrential floodwaters that left at least 3,000 people dead and over 4,200 still missing, was both predicted and preventable. And they won’t be the last big dams to collapse unless we remove and repair some of the aging and obsolete structures that are long past their expiration date.
Like many dams around the world, the Wadi Derna dams in Libya were built in the 1970s during the era of peak global dam construction, when 1,000 large dams were installed each year. Now most of these dams are reaching the end of their life spans.
Details are still emerging, but the Libya dam collapses appear to have been caused by poor maintenance, and by poor monitoring of reservoirs that were overwhelmed by a huge rainstorm. Critical warnings were issued last year about the dams’ deteriorated state and the repairs needed to avert such a scenario, yet no action was taken.
Similar disasters are waiting to happen around the world. The biggest danger is in India and China, where the 28,000 large dams built in the mid-20th century are now nearing obsolescence. Mullaperiyar Dam in Kerala, India, is over 100 years old, visibly damaged and located in a region prone to earthquakes. Its collapse would harm 3.5 million people downstream.
In the United States, the second most prolific dam-builder after China, the average age of dams is 65 years old and an estimated 2,200 structures are at high risk of collapse. The recent infrastructure law directs $3 billion into maintaining some of them, but there are still thousands of dams the federal government is not responsible for, and it will cost an estimated $76 billion to fix them.
The risks from ageing dams are of particular concern in the face of climate change. Dams are designed to withstand worst-case conditions as they can be imagined at the time of construction. But what were once considered once-in-a-century weather events have begun occurring with increasing regularity, putting dams at great risk of either failure or a significant weakening of their integrity.
Before the disaster in Libya, extreme weather worsened by climate change was already taking its toll on these structures. Heavy rainfall damaged California’s ageing Oroville Dam in 2017, prompting mass evacuations amid fears of major uncontrolled releases. A piece of a Himalayan glacier destroyed one dam and damaged another in northern India in 2021, killing dozens of people. Glaciers melting rapidly as a result of warming are now a major safety hazard to dams and communities living downstream.
The default approach has been to repair ageing dams where needed, monitor reservoir levels and try to anticipate rainfall and increased flows from upstream. Take the Kariba Dam on the Zambezi River in southern Africa, which is undergoing extensive repairs to prevent its collapse after the riverbed below it was found to be severely weakened. At a cost of $300 million, these repairs are required simply to keep the dam standing on a river where hydroelectricity production has already plummeted from drought. Projects like these essentially paper over the cracks, and are often significantly more expensive in the long run than removing dams that are already obsolete.
While some ageing dams still supply drinking water and help farmers irrigate their fields, many that were built for hydropower only generate a fraction of the electricity they once did as sediment accumulates behind their walls. Deepening drought linked to climate change has also crippled hydropower generation all over the world, leading to energy rationing and blackouts in the United States, China and Brazil.
The fact that it’s increasingly difficult to justify many dams’ existence is one reason there is a growing movement, often led by Indigenous peoples and other marginalised populations, to remove them. Most notably, the removal of four dams on the Klamath River along the Oregon-California border, set to be completed next year, will be the largest such effort in history.
Dam removal and river restoration are also picking up speed in Europe. Its rivers are among the most highly fragmented in the world, and have seen large declines in freshwater biodiversity. The River Meuse restoration project in the Netherlands, which includes restoring its floodplains to address flooding and drought, is expected to reduce extreme inundation from once in a century to once every 250 years.
The tragic dam disaster in Libya is a warning siren for other ageing dams around the world. Our best tool is removing them altogether. We must start using it much more often.
(Josh Klemm and Isabella Winkler are co-directors of International Rivers, a group that advocates for healthy rivers and the rights of river communities.)
This article originally appeared in The New York Times.
Ulitakiwa kusema "yote ni majengo" na sio "yote ni jengo". Alafu guest, nyumba,frem sio kitu kimojaBwawa ni jina tu lakini yote ni jengo kanuni zile zile.
Nyumba,guest,frem, ghorofa zote ni kitu kimoja
Sio bwawa hata hio Barabara ya mwendo kasi bado haijaanza kutumika lkn zege linatoa nyuma inabidi mkandaras anakat wanaweka viraka ni dalili ubora hafifuBora hata hayo tunajua yamekaa muda mrefu, je na lile ambalo halijaanza hata kutumika na lina nyufa itakuaje?
Yote ujengwaUlitakiwa kusema "yote ni majengo" na sio "yote ni jengo". Alafu guest, nyumba,frem sio kitu kimoja
Ohooo, sikujua mkuu!Achana nao hawa,ukoo wa yule jini mla damu za watu