WEBVTT
Kind: captions
Language: en

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I'm about to step onto brand new land.

2
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And admittedly, yes, it is a
little bit underwater right now

3
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because, well, that
river there is in flood.

4
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But 50 years ago, this
would've been open water

5
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and I would've been jumping
off this boat up to my neck.

6
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And yes, I was extremely nervous

7
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about that little jump [laughs]

8
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'cause that's the first
time I came off here.

9
00:00:35.630 --> 00:00:37.940
But yeah, this is the Wax Lake Delta.

10
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50 years ago: no trees, no plants,
nowhere to put your feet,

11
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I would've been swimming,
on a coastline that's famous

12
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not for building up but for eroding.

13
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And to explain why, we have to
go just a little bit inland.

14
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The Mississippi River
is so murky and brown

15
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because it's filled
with silt and sediment.

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Throughout history, roughly
every thousand years or so,

17
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deposits of that sediment build up enough

18
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that the river basically blocks itself

19
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and then takes a different and
steeper route to the ocean,

20
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at least until silt builds up
on that new route

21
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and the river moves again.

22
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That massive and relatively sudden change

23
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is called an avulsion.

24
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And avulsions were fine
until modern times,

25
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when the industry that you can hear

26
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and the livelihoods of
untold numbers of people

27
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rely on the river being
exactly where it is.

28
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But in the past, every time that humans

29
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have tried to fix the rivers around here,

30
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there have been unintended consequences.

31
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We built levees like this one

32
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to protect towns like Baton Rouge here,

33
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but they make the river
flow faster and higher

34
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because all the water is now
concentrated into one channel.

35
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And because they restrict water flow,
they move the flooding upstream,

36
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which means the next neighbourhood over

37
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has to build their levee
higher to deal with it.

38
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There are regulations
to prevent 'levee wars',

39
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when communities have to keep
building their levees higher

40
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because their neighbours
are doing the same.

41
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Those regulations aren't always followed.

42
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And downstream, levees mean that
instead of a wider river during floods,

43
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you get a faster river, eroding away those
silt and sediment deposits,

44
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literally washing away the
land that it once created.

45
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And now, the river doesn't flood as much,

46
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so the ground next to it
dries out and settles and sinks.

47
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Louisiana's coastline is disappearing.

48
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In 2011, government cartographers
retired 35 placenames,

49
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taking them off the maps

50
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because those islands and bays
just don't exist anymore.

51
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They're just open water.

52
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But there is one place on the coastline,
a couple of hours south of Baton Rouge,

53
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where land is appearing again,

54
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and that is also an
unintended consequence,

55
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which brings us back
to where I was standing

56
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at the Wax Lake Delta.

57
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- The Wax Lake Outlet is a
channel off the Atchafalaya River.

58
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The Atchafalaya River is a
channel off the Mississippi.

59
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So, a channel off a channel off
the Mississippi River. [thunder booms]

60
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Excuse me, I heard a little thunder.

61
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- Okay, no, we--
- Let's get out of here.

62
00:03:00.680 --> 00:03:04.860
- The Wax Lake Outlet was
built in the early  1940s

63
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and it was designed to pull water
off the Atchafalaya River

64
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and reduce flood stress on Morgan City.

65
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One of the unintended consequences

66
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was the development of a delta
at the mouth of the Wax Lake Outlet.

67
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And so, the Wax Lake Outlet
and the Atchafalaya River

68
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carries a lot of sediment,

69
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and then when it gets to the coast,
the river flow slows down

70
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and all of the sediment
in the river settles out.

71
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We're talking tens of millions
of metric tonnes of sediment every year.

72
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This is solid enough land
that you can walk on it

73
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and you can stand on it.

74
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Louisiana has lost nearly 2,000 square miles'
worth of land over the last century,

75
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and there's a large effort
to rebuild the coast.

76
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A big part of that effort is
to try to partially divert

77
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the flow of the Mississippi River

78
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to create new deltas that
are like the Wax Lake Delta.

79
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And so, people like myself want
to study the Wax Lake Delta

80
00:03:57.960 --> 00:04:00.040
so we understand how deltas build

81
00:04:00.040 --> 00:04:03.560
so we can better design
coastal restoration projects.

82
00:04:03.560 --> 00:04:05.420
It's important to restore the coast,

83
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one, to push back the sea to
enhance flood protection in Louisiana,

84
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and it's also a place where you could
potentially bury carbon.

85
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We have too much CO2 in the atmosphere,

86
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and highly productive
deltas like the Wax Lake

87
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may be one of those places
where we can do that.

88
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I often feel like the numerical models

89
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that we have to understand the
coast are pretty darn good.

90
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The much more difficult thing to model
is to understand people

91
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and how people are going to behave
with this changing coast.

92
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And I feel like, that, we barely
even know the equations.

93
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We don't necessarily know
even what the rules are

94
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to govern how do people deal with
a stressful changing environment.

95
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- So, yes, it's still wet
underfoot here right now

96
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because this whole area's still in flood.

97
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But that just means there's more mud,
more sediment being deposited.

98
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This land is going to be a
couple of centimetres higher

99
00:05:00.250 --> 00:05:03.163
and this coastline is going
to be just a little bit safer.

100
00:05:05.220 --> 00:05:06.800
I've sunk about an inch into the mud

101
00:05:06.800 --> 00:05:09.860
and it's gone in my shoes.
It's in my shoes.

102
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Right, I should totally
have gone with the sandals.

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[laughing]

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[grunts] All right.