POSSIBLE ALTERNATIVES TO THE ROLLING THUNDER PROGRAM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78T02095R000900070048-0
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 13
• Document Creation Date: December 21, 2016
• Document Release Date: April 23, 2008
• Sequence Number: 48
• Publication Date: July 22, 1968
• Content Type: IM

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Secret
DIRECTORATE OF
INTELLIGENCE
Intelligence Memorandum
POSSIBLE ALTERNATIVES TO THE ROLLING THUNDER PROGRAM
(The case in which the Rolling Thunder Program that
existed prior to 31 March is modified to include
attacks against inland water control facilities.)
(No. 4)
JCS review completed with referral to USAF
Secret
22 July 1968
Copy No. 8
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CENTRAL INTELLIGENCE AGENCY
Directorate of Intelligence
July 1968
Possible Alternatives
to the Rolling Thunder Program
(The case in which the Rolling Thunder Program
that existed prior to 31 March is modified to in-
clude attacks against inland water control facili-
ties.) (No. 4)
Summary
Attacks against North Vietnam's dams and dikes,
particularly the latter, could add appreciably to
the adverse effects on North Vietnam of a resump-
tion of the March 1968 Rolling Thunder Program,
previously discussed in Question 10. A highly
successful campaign could destroy as much as 25
percent of the annual rice crop. These water
control facilities are not easily destroyed by air
attacks, however, and the international reaction
to the bombing of dams and dikes would be extremely
unfavorable to the United States.
With one possible exception -- the 850-foot-
long Dan Phuong Dam -- successful attacks against
locks and dams would have little impact on North
Vietnam's transport system or on Hanoi's war-
supporting capabilities. A successful attack
against the Dan Phuong Dam would cause serious
flooding of valuable farmland southwest of Hanoi,
but this dam would be extremely difficult to attack.
The most serious effects would result from a
successful breaching of the elaborate system of
Note: This memorandum was produced solely by CIA.
It was prepared by the Office of Economic Research
and was coordinated with the Office of Current
Intelligence and the Director's Special Assistant
for Vietnamese Affairs.
JCS review completed with referral to USAF
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dikes in the Red River Delta. In addition to its
impact on rice crops, a successful breaching of
the primary and secondary levees in the Hanoi area
would produce the following short-term severe
disruptions:
Most of the economic and military
activity in Hanoi and its suburbs would
be temporarily halted.
A number of significant military
and industrial targets are located in
potential flood areas. These include
the Gia Lam and Bac Mai Airfields, the
railroad yard and port facilities at
Hanoi, and several major military
barracks and storage areas and head-
quarters installations.
Key transport routes leading south
and west from Hanoi, including Route lA
and the Hanoi-Vinh rail line, would be
disrupted.
A sizable diversion of labor would
be necessary for a period of weeks to
repair flood damage.
The most significant results (and the most diffi-
cult to obtain) would be accomplished by a
breaching of the levees during the high-water
period between mid-July and mid-August. A
successful attack at this time could produce
losses from flooding of as much as one million
tons of paddy rice. Hanoi would have to rely on
external sources to replace these losses. The
added import burden ---- up to 2,500 tons of milled
rice a day -- is well within the present estimated
capabilities of the rail and road connections with
Communist China.
The number of civilian casualties resulting
from this campaign would be small, and, with con-
tinued aid from its allies, North Vietnam could
soon adjust to the situation. Hanoi would, how-
ever, capitalize on opportunities presented by
the attack to launch a heavy propaganda effort to
put intense political pressure on the United States.
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Inland Waterways
1. The Red River Delta contains the most im-
portant waterways of Vietnam -- the Red River, the
Song Thai Binh River, and their two connecting
waterways, the Canal des Rapides and the Canal des
Bambous (see the map). These waterways connect
the country's principal urban centers -- Hanoi,
Haiphong, and Nam Dinh. Fertilizer, foodstuffs,
petroleum, and other imports are moved from Haiphong
in part by inland waterways, as is the coal mined
in the Hon Gai and Cam Pha areas. Since the Rolling
Thunder Program was inaugurated, an increasing
number of water craft have been used to distribute
POL directly from ocean tankers to dispersed storage
and transshipment sites along Delta waterways and
to aid in moving material from the port of Haiphong.
Most of North Vietnam's farmland is in the Delta;
it is dependent on irrigation during the dry months
and is endangered by :flooding in the wet months.
Furthermore, much of North Vietnam's urban areas
in the Delta are below the wet-season crests of
these Delta rivers.
2. The Panhandle region of southern North
Vietnam also contains navigable waterways, but
they are less important than the waterways in
the Delta. The most important inland waterway
south of the 20th Parallel is the waterway between
Thanh Hoa and Vinh. There are no through inland
water routes from North Vietnam into Laos or South
Vietnam. However, infiltration movements south-
ward are facilitated by short overwater hauls and
the extensive transshipment capability of the
waterway system. For example, supplies shipped to
Vinh via rail and highway are frequently ferried
across the Song Ca River or moved in watercraft
on short-distance hauls toward Mu Gia or south
toward the DMZ. Other areas of watercraft activity
and transshipment are at Ha Tinh, Quang Khe, and
Dong Hoi. Waterways in the Panhandle also support
small agricultural communities near Thanh Hoa and
Vinh.
3. The Song Thai Binh River is the only major
waterway in the Red River Delta that has naviga-
tion locks to control water levels and facilitate
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NORTH VIETNAM: Major Inland Waterways
102
North Vietnam
Road
--.:-- Railroad (meter gouge)
Major inland waterway
104
1 oR
DEMARCATION LINE
Quang Trt
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LAOS L.
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transport along otherwise unnavigable stretches.
These locks control water traffic to Thai Nguyen.
Currently, water transport to Thai Nguyen is of
little importance because bomb damage to the
area's industry has sharply reduced transport
requirements. A number of secondary waterways in
the Delta have navigation locks, but these water-
ways do not handle significant amounts of traffic
for urban centers.
4. In the Panhandle, a large number of small
locks are found in and around Thanh Hoa and Vinh,
but only a few of these locks have significance
for waterway transport. The Ben Thuy Lock connects
the main north-south inland waterway in this
region with the Song Ca River at Vinh. The Trung
Luong Lock on the Song Nghen River connects Vinh
with Ha Tinh.
5. Because of their low profile and strong
construction, locks are not vulnerable targets.
Most of the locks consist of a single basin formed
by earth slopes faced on the water side with loose
stone or other masonry. Bulkheads containing
steel or wood entrance gates at the end of the
basins are usually made of reinforced concrete
backed by earth fill. The most vulnerable parts
of the locks are the gates. They can be destroyed
or rendered inoperative by a small bomb, but a
direct hit would probably be required. Severe
damage to locks probably could be repaired within
six months.
6. Successful attacks against North Vietnam's
locks would have little impact on North Vietnam's
transport system. Inland watercraft could be
diverted to waterways not dependent on locks.
Cargoes intended for water transport could be sent
by the many alternative rail or highway routes
that parallel the inland water network. Because
of accidental bomb damage, the Ben Thuy Lock and
two of the eight JCS-targeted locks are not now
being used, yet water transport in the vicinity
of the damaged locks seems to be unaffected.
7. Dams to control flooding and irrigation
are located throughout North Vietnam, primarily
in the Red River Delta. Some of these dams could
be breached by a small number of hits during
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periods of high water, when current velocities are
greatest and the high water creates maximum pres-
sure. The prospects for causing significant flood
damage or disruption of water transport are limited.
Most of the dams are small; they are made of packed
earth, are less than 60 feet long, and are less than
10 feet high. The few larger dams are constructed
of concrete and often have gates to permit through
navigation of watercraft. Earthen dams can be re-
paired quickly with primitive materials and almost
no construction machinery. A significant exception
to North Vietnam's small and unimportant dams is
the 850-foot-long Dan Phuong Dam near the junction
of the Red and Song Day Rivers that protects
valuable farmland southwest of Hanoi from flooding.
The dam is a low, massive concrete structure,
however, that would not be very susceptible to
air attack.
Dikes
8. Dikes to control flooding and the course
of the waterways are located along all of North
Vietnam's major rivers, but they are most impor-
tant and most fully developed along the Red River.
The Red River dike system begins near Viet Tri,
which is only 43 feet above sea level although about
100 miles inland at the northwest head of the Delta.
From that point the river falls an average of
6 inches per mile to the sea. The great amount
of silt brought down from the mountains and
deposited along the river beds in the Red River
Delta has raised the waterways above the sur-
rounding countryside in many places and required
the constant elevation of the restraining walls.
In some areas, particularly around Hanoi, the
height of the dikes reaches 40 feet. The primary
system of dikes is backed up by a secondary
system, between 4 and 22 feet high, that runs
parallel to the main dikes. This secondary
system is designed to localize and minimize
damage if the primary dikes are breached. A
tertiary system of smaller dikes has also been
built to divide the rice-growing plains into
compartments and to assist irrigation. These
latter dikes also control the level of small
streams and local waterways. In addition, the
river dike system is complemented by small
natural or manmade dikes along the coast which
keep out brackish seawater.
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9. Dikes are particularly difficult to damage
by air attack. Those in the primary system can be
breached only by a series of overlapping craters
across the entire top of a dike. The dikes along
the right bank of the Red River have a width at
the top of approximately 80 feet. Moreover, the
lips of the bomb craters must be sufficiently lower
than the surface of the river to initiate the flow
and subsequent scouring action of water rushing
through the breach. A destructive force equivalent
to a train of eleven 1,000-pound general-purpose
bombs, which would penetrate about 10 feet in
average soil and produce craters 37 feet in diam-
eter, would probably be needed to breach the Red
River dikes. To achieve a 50-percent assurance of
breaching a primary levee, five of these eleven-
bomb trains would be required. Furthermore,
simultaneous breaching at two or more points is
desirable to disperse salvage operations and to
obtain maximum flood damage. Additional strikes
against the secondary dike system would be necessary
to preclude these supporting dikes from absorbing
the effects of the breaching of the primary levees.
10. Various countermeasures are available to
the North Vietnamese even if the dikes are breached.
Barges could be floated into the opening and sunk,
creating the beginning of a temporary coffer dam.
Once the flow of water through the gap was under
control, the dike could be repaired quickly. In
anticipation of attacks on the water system in 1965
and 1966, the North Vietnamese apparently collected
barrage materials in the Hanoi area to fill breaches
in the dikes, and this material is probably still
available. Defensive breaching of the dikes up-
stream from a bomb breach could cushion the impact
of the attack and could rapidly drop the level of
flood water at Hanoi by as much as six feet. In
this way, less important areas would be sacrificed
to save urban or key agricultural regions. Dams
and other water-control facilities along the major
waterways could also divert much of a threatened
river's volume. For example, an estimated 10 per-
cent of the Red River's flood volume could be
diverted into the Song Day River by the dam at Dan
Phuong. This is more than the Song Day can handle,
but the excess would be deposited on agricultural
areas which are presumably less valuable than the
urban areas around the capital.
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Flooding
11. The agricultural areas in North Vietnam
most vulnerable to flooding are the Ha Dong area,
a flat, densely populated rice-growing plain south-
west of Hanoi lying between the Red River and the
Song Day River, and the Gia Lam - Ban Yen Nhan
area, a flat, rice-growing plain east of Hanoi,
bordered by the Red River and Canal des Rapides
(see the map). The Ha Don.g area is a saucer-like
plain only six feet above sea level at its lowest
elevation. It is frequently inundated by heavy
rainfall and probably could not be drained after
flooding in less than a month. The Gia Lam - Ban
Yen Nhan area, however, is high enough to be drained
readily even during high water.
12. The principal impact of flooding resulting
from air attacks against the dikes and dams would
be on the rice crop -- the staple food in North
Vietnam. If the dikes are breached between mid-
July and mid-August, when the Red River is at its
height, a substantial part of the tenth-month rice
crop -- normally about two-thirds of the annual
harvest -- would be completely destroyed by flooding,
if the submersion of the rice plants persisted be-
yond two weeks. The rice plants are also vulnerable
to shorter periods of submersion during mid-August
after transplanting. A successful attack that
managed to breach both the primary and secondary
levees could cause crop losses from flooding of as
much as one million tons of rice, or about 25 per-
cent of North Vietnam's estimated 1967 production.
13. Hanoi would have to turn to outside sources
to make up its rice losses. These amounts could
be provided by North Vietnam's Communist allies,
although they might be forced to procure offsetting
amounts of grain in the Free World markets. The
transport of these food supplies could be difficult,
depending on the extent of damage to transport
systems and the effectiveness of other interdiction
programs. The losses could be replaced over a nine-
month period during which the added import require-
ment would be a maximum of 2,500 tons of milled
rice a day.* This increase in import traffic is
well within the current capabilities of North Viet-
nam's rail and road transport connections to Com-
munist China.
* This calculation is based on the assumption that
700,000 tons of milled rice would be imported.
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14. Most of the industrial, commercial, and
military activity in Hanoi and its suburbs would
be temporarily halted until the water receded.
Included in the installations that would be affected
are Gia Lam Airfield, the Hanoi Port Facilities,
the Hanoi Railroad Yard, the Hanoi Engineering and
Machine Tool Plant, the Hanoi Thermal Powerplant,
and a number of recently constructed modern indus-
trial facilities -- the Hanoi Rubber Products
Plant, the Hanoi Soap Plant, the Hanoi Machinery
Plant Gia Lam, and probably the 8th March Textile
Plant. Military barracks, POL and material storage
areas, air defense sites, and communications facili-
ties would also be affected. To mitigate the
effects of the flooding, Hanoi would be forced to
divert an undetermined but very sizable work force
away from other activities, including those of a
military-supporting nature, for a period of weeks
until the major damage had been repaired. Contin-
gency measures devised from operating under the
annual threat of floods, however, probably would
minimize serious physical damage, and it seems
likely that the flooding effects would be temporary.
15. In addition to halting economic and military
activity in the Hanoi area and submerging valuable
farmland, the destruction of dikes and dams would
disrupt transport routes. The transport routes
most vulnerable to flooding include the Hanoi-Vinh
rail line, Route 1A between Hanoi and Phu Ly,
Route 10 southwest of Haiphong, Route 11A west of
Hanoi, and Routes 6 and 212 southwest of Hanoi.
Some portions of Route 5 between Hanoi and Haiphong
would probably also be affected.
16. The extent of destruction caused by flooding
in the Panhandle would not be as widespread as in
the Delta area. Land routes would probably become
blocked at least temporarily at the major river
crossings, hindering the southward movement of
goods.
17. The breaching of the dikes in the Hanoi area
would not necessarily result in a large number of
casualties. JCS pre-strike estimates of the
number of casualties resulting from the actual
bombing attacks do not exceed 200. This number
could be less in view of the population's experience
in taking shelter from air attacks. The number of
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casualties resulting from flooding would also be
limited because of North Vietnamese contingency
planning and countermeasures and because the areas
to be breached are areas in which flooding has
been common; housing, for example, has been built
to withstand high water levels.
Political Reactions
18. The principal effects of attacks on inland
water control facilities would fall on the civilian
population with only secondary effects on military
targets. If the attacks successfully breached the
levees and caused widespread flooding, world reaction
would be highly unfavorable. The campaign would be
viewed by most observers as an unconscionable esca-
lation of the war. It would be extensively exploited
in Hanoi's propaganda in order to put iitense
political pressure on the United States.
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