沿海恢复和弹性：使受损湿地起死回生
Beaches and parks on Delaware Bay are threatened by rising sea levels and increasing natural disasters — but a new plan to build in coastal resilience could provide a model for other similar areas.
这篇文章最初发表于耶鲁E360.
Standing atop a 10-foot dune at thePrime Hook National Wildlife Refuge在特拉华湾，避难经理铝佐介绍修复工程安装过的最大，最复杂的湿地之一，一个$ 38万试图返回4000英亩回什么性质打算。
Contractors hired by the U.S. Fish and Wildlife Service dredged more than 1 million cubic yards of sand from Delaware Bay to create 2 miles of beach and barrier dune that had been washed away by a series of storms beginning in 2006 and culminating with Hurricane Sandy in 2012. To stabilize the recreated dune, workers then planted half a millionAmerican beachgrass (PDF)plugs and erected 10,000 feet of fencing. Down the beach, Fish and Wildlife staff are enclosing the nests of piping plovers, a threatened species that started breeding at the refuge only three years ago.
Inland, new plantings of狐米草- 原生盐草地这对水位和盐度敏感 - 捅掉在了地上，一个健康的湿地的指标。纵观总理挂钩湿地，挖泥船已在试图恢复咸和苦咸水的自然流动刻25英里通道。沉积物由该项目产生的600000立方码被投射到银行，形成正由自然殖民沙地互花米草另一本地草。
The goal of this work is to reverse the damage created by an ill-conceived project in the 1980s that aimed to convert Prime Hook’s salt marsh into a largely freshwater impoundment system, in part to attract more ducks, geese, and other birds for hunters and birdwatchers. But what Rizzo and others see at Prime Hook is more than the resurrection of a single marsh. They see a model for restoring vital wetlands worldwide by taking design cues from nature to recreate a resilient ecosystem — an increasingly vital task as climate change threatens coastlines with rising sea levels and stronger storms.
在总理挂钩项目工作的科学家说，它是有生命的实验，以更好地了解什么可行，什么不可行的湿地的恢复。为此，他们已经开发出一种复杂的monitoring system (PDF)that records water flow, dissolved oxygen levels, sediment flow and other key markers. The goal is to rebuild a ;健康潮汐沼泽with meandering channels, lush salt-tolerant grasses, and mudflats that attract a rich diversity of fish and birdlife.
“每一次修复基本上是一个研究项目，”说Chris Sommerfield, a University of Delaware oceanographer who is tracking sediment flow in and out of the refuge, a key to building habitat for grasses. "Every site is different. Every time we do a restoration we learn a lot that we can translate into better restoration practices. That’s important because we will be restoring wetlands forever."在总理挂钩项目工作的科学家说，它是有生命的实验，以更好地了解什么可行，什么不可行的湿地的恢复。
A key element in reversing that trend will be efforts to revitalize degraded marshes and devise strategies for protecting coastal wetlands as sea levels rise. And what researchers have confirmed in recent years is what land managers have been seeing anecdotally: Coastal wetlands, when preserved or restored, reduce flooding and erosion better than hard infrastructure such as seawalls and levees. And they do it at a lower cost. In onerecent study, researchers found that wetland restoration provided $8 in flood reduction benefits for every $1 invested. The study also found that solutions such as marsh and oyster reef restoration could help prevent more than 45 percent of flood damage over a 20-year period in the Gulf of Mexico alone, saving more than $50 billion.
But that’s only a portion of the value of wetlands. Although they cover less area globally than forests, wetlandssequester carbon更有效地比林地。在2018纸，Sommerfieldvalued carbon sequestrationof tidal wetlands in the Delaware River estuary at $42,000 per square kilometer. The researchers noted that the estuary lost aboutan acre per dayof wetlands from 1975 to 2011.
特拉华州的季度仍然湿地。像许多国家，它有一个计划以节约（PDF）和恢复它们。该州还签署切萨皮克湾流域协议，其目的是create or reestablish 85,000 acres湿地，并在2025年提高15万英亩海湾健康。
拉姆萨尔公约由168个国家签署了要求一个"wetland decade"from 2021 to 2030 to restore and preserve wetlands. In the United States, the National Oceanic and Atmospheric Administration has created a wetlands Restoration Center, and the U.S. Army Corps of Engineers, long builders of human-centric infrastructure solutions, has begun anEngineering With Nature Initiative.
Engineering with nature is how Rizzo and Bart Wilson, Prime Hook’s restoration project manager, describe their approach to restoring nearly half of the refuge’s 10,000 acres. The Prime Hook National Wildlife Refuge was established in 1963, and until the 1980s, it remained a healthy East Coast salt marsh. Then, managers decided to convert a portion into a freshwater marsh with large areas of open water to attract more migratory waterfowl, among other things. Tide gates were installed across creeks and a canal, reducing the flow of saltwater from Delaware Bay. Freshwater surface runoff was allowed to increase.
A series of storms starting in 2006 opened breaches in the refuge’s line of dunes, inundating the re-engineered system with saltwater, which killed the marsh grasses and turned a healthy riparian forest inland into a ghostly wasteland of skeletal trunks. A county road running through the refuge to a strip of homes on the beach flooded nearly every high tide. Saltwater crept into nearby farm fields, rendering them useless. The cycle of algae bloom and death led to fish kills.
“这是一个臭洞，”里佐说。人类与避难的水文搞乱创造了一个不自然的灾难。
目前修复工程，通过桑迪飓风灾害救助法与联邦资金资助，包括州和联邦机构的一个长长的清单，以及保育团体，如鸭子无限，大自然保护协会和特拉华州自然协会。
里佐和威尔逊雇用私人承包商做大量的水动力模型，依靠自2006年缺口已经收集到十年的数据。他们的目标是让自然听写的过程中，和模特说做的最好的方式是恢复自然水文所以水位会下降并重新创建沼泽。
Jeff Tabar, a senior coastal engineer with the global design firm Stantec ran the models with his team. "This scale of modeling had not been attempted before," says Tabar, who has worked on projects from New England to the Gulf of Mexico. "The intent was to have this design process and project be a template that could be used elsewhere for refuges, preserves, and restoration projects."
“你需要了解什么地方不对头，”威尔逊说。“如果你不明白这一点，你可以恢复它，它就会恢复回来。”
他们发现，避难所没有一个高度的问题;它有一个管道的问题。如果他们关闭在沙丘的漏洞和打开，通过基于历史潮汐通道避难航道，水位会下降，而不是被截留在蓄水池。泥沙会流向创造泥滩，设置阶段为植被殖民化。研究人员需要知道是否会有足够的盐生长和维持一个盐沼。他们需要得到的水位正确的三棱草生长。他们需要在沙丘的陆侧足够的泥沙建立植被的平台。
"Modeling doesn’t hold every answer," Wilson says, standing over before-and-after aerial photos of the refuge in a conference room, "but it puts you on a path using science to set you up for a good design and better success."
Restoration work began in October 2014 with the closing of the breaches by constructing the beach and dunes. The restored dunes are now nearly 10 feet high, allowing for overwash that will dissipate storm energy. Behind it, they built a platform of sand planted with grasses extending into the marsh. When the dune naturally migrates inland, rolling over from wave and storm action, it will have a place to land.
A面散大米，小米，和其他种子达1000余亩。随后，工人用手工散发小树苗。创建疏浚公司的什么佐挖25英里渠道，从而它曾经有过水会流要求避难的神经网络。
So far, the results are encouraging. Birds have returned, including a variety of ducks that hunters feared were gone for good. Eels, bass, crabs, perch, flounder, and other fish are increasing in numbers. But the project is still young. "In terms of the long-term trajectory, it’s too early to tell," Sommerfield says. "It will be another 10 years to know if the grasses are growing in the right location at the density to keep the landscape stable."
On a spring afternoon with an easterly wind blowing water into the marshes, Rizzo pulls over on Prime Hook Road, the refuge’s central artery. An electronic sign at the road’s entrance that warns drivers when it is flooded hasn’t blinked since the restoration; the marsh is once again naturally absorbing high tides and storm surge.
“这是相当惊人的，我们有尽可能多的再生，因为我们做的，”里佐说。小圈互花米草黑暗mudfl发芽自然点ats. Along the channels, grasses grow thicker. Phragmites, a non-native invasive grass, grows along the edges of the Spartina stands, but it’s been sprayed with herbicide, one of the few nods to continuing intervention.
"Our primary objective was to set the table to allow the system to adjust itself and work based on normal coastal dynamics," says Rizzo. "What we’re doing now is sitting back and watching."