مخاطر سد أوروفيل أنتهت وتكاليف ترميم أعلى سد في أمريكا تصل إلى 200 مليون دولار

أرشيف شبكة التأمل الإعلامية

نشر في: الخميس,16 فبراير , 2017 2:00م

آخر تحديث: الخميس,16 فبراير , 2017 8:47ص

188 ألفا من سكان منطقة أسفل سد أوروفيل في كاليفورنيا وهو أعلى سد في أمريكا، أذنت لهم السلطات بالعودة إلى بيوتهم وأعمالهم بعد إجلائهم منها في الأيام الأخيرة.

منوهة بضرورة اتخاذ الحذر وأن يكون الناس على أهبة الاستعداد لعمليات الإجلاء في حال ظهور مخاطر فيضانات غير محسوبة. كميات كبيرة من المياه تم ضخها عبر قناتي التصريف الرئيسة والمساعدة.

مدير العمليات في إدارة موارد المياه في كاليفورنيا – بيل كرويل، يقول: “عمل قناة التصريف استقر خلال أربعة أيام.

هذه مسألة مهمة اليوم وللأيام المقبلة، إذ نتنبأ بعاصفة، عواصف ضعيفة مقبلة، لكننا نتهيأ عمليا لما تبقى من موسم الأمطار”.

تصريف المياه الفائضة ساعد على خفض منسوب المياه في بحيرة السد إلى الحد الآمن.

ولم تعد الأمطار الغزيرة المحتملة تشكل تهديدا بارتفاع منسوب المياه إلى المستوى الخطر الذي ينذربتخريب المنشأة وإحداث فيضان وغمر لمناطق أسفل السد.

الخطر الأعظم كان نتيجة حدوث انهدام في قناة التصريف الذي سمح بتسرب المياه من الحوض عندما ارتفع منسوب المياه. رغم التخريب مازالت قناة التصريف الرئيسة صالحة للعمل

وأفادت وكالة المياه في كاليفورنيا بأن إصلاحات وترميم الأضرار التي طالت سد “أوروفيل” الأعلى في الولايات المتحدة سوف تتراوح تكلفتها بين 100 مليون و200 مليون دولار.

وأوضح مدير هيئة الموارد المائية “بيل كرويل” أن عدة فرق متخصصة ذهبت اليوم لاستكشاف أعمال وخطط الترميم والإصلاحات للسد.

وأكد “كرويل” على أن التكلفة المبدئية تم تحديدها بناءً على معلومات محدودة حيث إن الترميمات طويلة المدى ربما تبدأ بعد فصل الربيع عندما يتمكن الطاقم الفني من سد فتحات التدفقات المائية.

كانت السلطات الأمريكية قد أمرت بإجلاء ما يقرب من 200 ألف شخص قريبين من سد “أوروفيل” شمال كاليفورنيا بسبب ظهور علامات تدل على انهيار وشيك.

Evacuation: Almost 200,000 people were ordered to leave the towns downhill of the Oroville Dam on Sunday as heavy rainfall left it at risk of bursting. On Monday it emerged that authorities had ignored warnings about a possible collapse 12 years ago

Floods: The spillways were not reinforced, and on Monday Riverbend Park was left submerged by the flood water. Officials said the threat had subsided for the moment. However, things could get worse

Ghost town: The streets of Oroville, which is directly below the dam, stand empty and still on Monday. That same day it emerged that repairs on the dam were not earmarked in California Gov. Jerry Brown's $100b list of key projects this month

Gone: Just two vehicles remain in this shopping mall's parking lot in Oroville, after warnings that the dam might burst. They have been told they may not be able to return until repairs on the dam have been completed

No-one home: An Oroville street stands empty just two days before expected heavy rain potentially puts the whole down at risk of being drowned under 100ft of water

Marooned: A home in Oroville is seen marooned on a tiny island after the dam's spillways released excess water into the area. The dam's main spillway was damaged by the heavy flow of water after recent storms

Swamped: This farm was flooded by the overspill from the dam. Protesters demanded 12 years ago that the spillways be reinforced with concrete that would properly funnel the water and reduce risk of flooding such as this

Going nowhere: Vehicles and carts are seen trapped in the swamp - for how long remains to be seen. Officials responded to the 2005 request for spillway reinforcements by saying there was no risk of this kind of flooding

Damaged: A damaged property is seen under flood waters in Oroville on Monday

Drowned: Riverbend Park, on the shore of the Feather River, was especially badly hit: This cabin was only just seen poking out of the water there Monday

Underwater: This playground at Riverbend Park was left submerged by the excess water

Underwater: This photograph shows just how badly submerged Riverbend Park is by the murky brown water

Swamp: An orchard is turned into swampland as flood waters rise near Oroville, California on Monday

Floods: A cemetery in Marysville is inundated with water on Monday. The dam's largely earthen emergency spillways eroded due to the heavy waterfall, causing a loss of control. More rain is expected on Wednesday - which could lead to a 'tsunami'

Erosion: The problems are caused by the dam's spillways, which carry off excess water. The main spillways has a 250ft hole that is being eroded from underneath

Torrents: The other spillways are just earth, which was washed away by torrents of water

Fear: There are fears that the ground beneath the dam's concrete wall will erode during Wednesday's rain, causing the wall to collapse. If that happens, thousands of tons of water will rush forward in a 30ft 'tsunami'

Repairs: A helicopter prepares to drop a load of rocks to fill a hole in the lip of the dam. Other boulders were being trucked up to the dam to fill the hole in the concrete run of the main spillway

Destruction: An aerial photograph shows the damage done to the area surrounding the emergency spillway - including a torn-up road - at Oroville Dam after it nearly collapsed on Sunday

Repairs: Emergency repairs are now being performed on the primary and auxiliary spillways, in the hope that they can be made functional before Wednesday's projected heavy storms

Spilling over: The spillways were not reinforced with concrete, leading to heavy damage this month after a sudden burst of heavy rainfall caused torrents of water to flow out of the dam

Construction: Heavy rocks are piled up in an effort to repair the damaged spillway below the dam on Monday. Concerns remain high about the possibility of a dam-busting rainfall

Supplies: Trucks stacked high with rocks are running up to the dam, where workers are loading them into the spillway

Repairs: Bags stuffed with rocks are being lifted by a helicopter to be dropped into a hole in the lip of the dam

Delivery: A large truck full of rocks crosses the primary spillway on the way to deliver its cargo to the damaged emergency spillway at the dam on Monday

Dropped off: The truck empties its load of rocks onto the damaged spillway so that it can be fixed up

Evacuees: Evacuees rest on campbeds in the shelter, located in Chico, around 22 miles northwest of the Oroville Dam. They were told that they would not be allowed to return until the dams' spillways were repaired

Sheltered: One-year-old Jace Lawson sleeps in a shelter for people evacuated from Oroville and other towns that could be submerged if the dam breaks

Neighbors: Merna Thompson (left) and Delores Dearte, neighbors from the town of Gridley, California (16 miles southwest of the dam), rest up in the shelter

Waiting: Evacuees wait in another shelter that has been set up in a high school gym in Sutter, California, around 30 miles southwest of Oroville, out of the reach of the projected flood zone

Power: A water utility worker stares at the staggering amount of water being released down the main spillway at the Oroville Dam after its spillway almost collapsed on Sunday - sparking the evacuation of 200,000 people 

Still pouring: Water continued to run down the main spillway at Lake Oroville on Monday. The water level dropped overnight behind the nation's tallest dam 

Inspection: State officials waited for the light of dawn to inspect an erosion scar on the main spillway at northern California's Oroville Dam

Flowing: As the day began, officials from the California Department of Water Resources prepared to inspect an erosion scar (pictured) on the main spillway at the dam on Lake Oroville, about 150 miles northeast of San Francisco

Looming danger: A California Department of Fish and Wildlife employee observes the rushing water as it drains down the spillway at the Oroville Dam after it nearly partially collapsed on Sunday

Raging: The water level dropped Monday behind the dam, reducing the risk of a catastrophic spillway collapse and easing fears that prompted the evacuation of nearly 200,000 people downstream

Hope: Water officials say storms expected later this week near communities evacuated over the threat of a spillway collapse at the nation's tallest dam will be smaller than last week

Complex: Water from the Oroville Dam Auxiliary Spillway at Lake Oroville continues to flow and has eroded the roadway just below the spillway that leads to the boat ramp

Fight: This long exposure photograph shows the Oroville Dam discharging water at a rate of 100,000 cubic feet per second over a spillway as an emergency measure

Overflow: Officials said on Sunday night water falling over the Oroville Dam's spillway has stopped as Oroville lake levels dropped low enough

Aerial: Lake water flows over the emergency spillway, bottom left, at Lake Oroville for the first time in the nearly 50-year history of the dam on Saturday

After years of drought Northern California has endured several months of exceptionally wet weather. Oroville and other lakes are brimming and have begun releasing water to make room for more runoff. An aerial photo released by the California Department of Water Resources shows the damaged spillway with eroded hillside in Oroville on Saturday

The auxiliary spillway at the Oroville Dam was expected to fail by 5:45pm local time on Sunday, which could have sent an 'uncontrolled release of flood waters from Lake Oroville'. Water continues to gush down the dam's main spillway on Saturday

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