NASA Project Examines Louisiana Delta System

 

Sinking land, a rising sea and other climate change effects have killed a wooded area in Louisiana where a Native American chief played as a child. In the nearby Mississippi River delta¹ system, middle-school students can stand on islands that formed the same year they were born.

NASA is using methods like air-based technology and boats on islands in a five-year, $15 million study of these places. One area is connected to a river and growing; the other is disconnected and dying.

Scientists from NASA and six U.S. universities are aiming to create computer models that can be used with satellite data. Together, the information can show countries around the world which parts of their deltas² are savable and which are past hope.

Marc Simard is lead scientist of NASA's Jet Propulsion Laboratory. He said if countries have to choose between saving one area or losing everything, it is good to know where their resources can help people.

Though oceans are rising because of climate change, the world's river deltas are sinking and getting smaller. Deltas produce much of the world's seafood³ and are home more than 300 million people.

To find out where to strengthen dying deltas, NASA is studying water flow in and out of two of Louisiana's river basins: the Atchafalaya and Terrebonne. They are examining the sediment⁴, and plants that can slow sediment flow and pull carbon gases from the air.

Louisiana holds 40 percent of the nation's wetlands, but they are disappearing fast. Around 5,180 square kilometers of them have been lost since the 1930s. That is about 80 percent of the nation's total wetland loss, says the U.S. Geological Survey agency.

The scientists are using two kinds of radar⁵ and a spectrometer device, which measures more colors than the human eye can see. High-technology NASA airplanes have been putting the instruments to work, collecting information on things like water height and the kinds and density⁶ of plants.

On boats and islands, scientists and students are measuring things like water currents and the width of trees. Their findings will be compared with those of the air-based instruments.

Robert Twilley is a professor of oceanography and coastal⁷ sciences at Louisiana State University, known as LSU. He told the Associated Press that one of the hardest parts of studying a delta is that you can only understand one small piece at a time. But working with NASA offers the ability to understand the whole delta, he said.

The Mississippi River collects 150 million tons of sediment each year. But, mainly because of flood-prevention systems, most sediment shoots into the Gulf⁸ of Mexico instead of staying in wetlands.

Sediment from the Atchafalaya River now fills Louisiana's Wax Lake Delta, which dates back to only 1942. At that time, federal engineers dug an outlet⁹ into the lake to reduce flooding in a city about 32 kilometers away. Sediment from the Atchafalaya River filled the lake. Then it began creating islands in the Gulf.

Older wetlands in areas surveyed by NASA's aircraft have more kinds of wildlife. And they have fertile soil from housing generations of plants. Along the nearby Hog¹⁰ Bayou area, for example, colorful birds fly through the trees. And in the very wet areas, osprey birds sit on top of cypress¹¹ trees and alligators¹³ float in the water below.

But the Terrebonne Basin is different. It is shrinking so fast that the government is paying to move a group of Biloxi-Chitimacha-Choctaw Indians from their island to higher ground.

They are not the only group of Native Americans losing land to the changes.

"The wooded areas we used to run through as children -- they're dead," said Chief Shirell Parfait-Dardar. She is from the Grand Caillou/Dulac Band of Biloxi-Chitimacha Indians. Her community is based less than 80 kilometers from the Wax Lake Delta.

Dead forests are common in failing deltas where saltwater floods in as land sinks and erodes¹⁵, LSU's Twilley said.

Louisiana is considering two projects that would move Atchafalaya River sediment to build land in the Terrebonne Basin. But a decision is more than a year away, says the state's coastal renewal¹⁶ agency.

In the Terrebonne Basin, sedimentation¹⁷ cannot keep up with sinking and sea level rise.

"All of the tools they're bringing to bear is really impressive," said Douglas Edmonds, a sediment expert with Indiana University. Although the scientist is not part of the project, he has worked with many of the researchers.

"The project itself is putting a finger on a really essential question for a lot of deltas around the world -- how this deltaic¹⁸ land is formed and what processes take it away," he said.

Words in This Story

delta – n. a piece of land shaped like a triangle that is formed when a river splits into smaller rivers before it flows into an ocean

basin – n. the area of land around a large river and the small rivers that flow into it

sediment – n. material (such as stones and sand) that is carried into water by water, wind, etc.

alligator¹² – n. a large reptile¹⁹ that has a long body, thick skin, and sharp teeth, that lives in the tropical parts of the U.S. and China, and that is related to crocodiles

erode¹⁴ – v. to gradually be gradually destroyed by natural forces (such as water, wind, or ice)

impressive – adj. deserving attention, admiration²⁰, or respect

essential – adj. extremely important and necessary

1 delta   

n.（流的）角洲

参考例句：

• He has been to the delta of the Nile.他曾去过尼罗河三角洲。
• The Nile divides at its mouth and forms a delta.尼罗河在河口分岔，形成了一个三角洲。

2 deltas   

希腊字母表中第四个字母( delta的名词复数 )； （河口的）三角洲

参考例句：

• Tidal channels, deltas, and washover fans are characteristically associated with offshore bars. 潮汐水道、三角洲和冲刷扇典型地与滨外砂洲伴生在一起。
• I know many of the early civilizations prospered on deltas. 我知道很多古老的文明都是在三角洲上蓬勃发展起来的。

3 seafood   

n.海产食品，海味，海鲜

参考例句：

• There's an excellent seafood restaurant near here.离这儿不远有家非常不错的海鲜馆。
• Shrimps are a popular type of seafood.小虾是比较普遍的一种海味。

4 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

5 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

6 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

7 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

8 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

9 outlet   

n.出口/路；销路；批发商店；通风口；发泄

参考例句：

• The outlet of a water pipe was blocked.水管的出水口堵住了。
• Running is a good outlet for his energy.跑步是他发泄过剩精力的好方法。

10 hog   

n.猪；馋嘴贪吃的人；vt.把…占为己有，独占

参考例句：

• He is greedy like a hog.他像猪一样贪婪。
• Drivers who hog the road leave no room for other cars.那些占着路面的驾驶员一点余地都不留给其他车辆。

11 cypress   

n.柏树

参考例句：

• The towering pine and cypress trees defy frost and snow.松柏参天傲霜雪。
• The pine and the cypress remain green all the year round.苍松翠柏，常绿不凋。

12 alligator   

n.短吻鳄(一种鳄鱼)

参考例句：

• She wandered off to play with her toy alligator.她开始玩鳄鱼玩具。
• Alligator skin is five times more costlier than leather.鳄鱼皮比通常的皮革要贵5倍。

13 alligators   

n.短吻鳄( alligator的名词复数 )

参考例句：

• Two alligators rest their snouts on the water's surface. 两只鳄鱼的大嘴栖息在水面上。 来自辞典例句
• In the movement of logs by water the lumber industry was greatly helped by alligators. 木材工业过去在水上运输木料时所十分倚重的就是鳄鱼。 来自辞典例句

14 erode   

v.侵蚀，腐蚀，使...减少、减弱或消失

参考例句：

• Once exposed,soil is quickly eroded by wind and rain.一旦暴露在外，土壤很快就会被风雨侵蚀。
• Competition in the financial marketplace has eroded profits.金融市场的竞争降低了利润。

15 erodes   

侵蚀，腐蚀( erode的第三人称单数 )； 逐渐毁坏，削弱，损害

参考例句：

• The sea erodes the rock. 海水侵蚀岩石。
• The sea erodes the land. 海洋侵蚀陆地。

16 renewal   

adj.(契约)延期，续订，更新，复活，重来

参考例句：

• Her contract is coming up for renewal in the autumn.她的合同秋天就应该续签了。
• Easter eggs symbolize the renewal of life.复活蛋象征新生。

17 sedimentation   

n.沉淀，沉积

参考例句：

• Sedimentation, the damage of a breach are problems, too. 而且沉积和决口的问题，也是存在的。 来自英语晨读30分（高二）
• Sedimentation and denudation play a role in exceptional cases. 沉积和剥蚀作用的影响只在特殊情况下起作用。

18 deltaic   

三角洲的，三角形的

参考例句：

• The river discharged into the western part of the deltaic plain. 河水排注到三角洲平原的西部。
• Cheniers are generally related to the deltaic environment. 滩脊一般与三角洲环境有关。

19 reptile   

n.爬行动物；两栖动物

参考例句：

• The frog is not a true reptile.青蛙并非真正的爬行动物。
• So you should not be surprised to see someone keep a reptile as a pet.所以，你不必惊奇有人养了一只爬行动物作为宠物。

20 admiration   

n.钦佩，赞美，羡慕

参考例句：

• He was lost in admiration of the beauty of the scene.他对风景之美赞不绝口。
• We have a great admiration for the gold medalists.我们对金牌获得者极为敬佩。