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Influence of climate and terrain on ground temperatures in the
continuous permafrost zone of northern Manitoba and Keewatin
Districk, Canada
National Research
Conseil national
I
+
Council Canada
de recherches Canada
INFLUENCE OF CLIMATE AND TERRAIN ON
GROUND TEMPERATURES IN THE CONTINUOUS
PERMAFROST ZONE OF NORTHERN MANITOBA
AND KEEWATIN DISTRICT, CANADA
RNHLYZL ,by
R
J.E.
Brown
Reprinted, with permission, from
Vol. 1, Proceedings 3rd International Conference
o n Permafrost
held in Edmonton, Alberta, 10
-
13 July 1978
p.
15
-
21DBR Paper No. 809
Division of Building Research
Price 1 0 cents
OTTAWA
NRCC
17085
INFLUENCE OF CLIMATE AND TERRAIN ON GROUND TEMPERATURES IN THE CONTINUOUS PERMAFROST ZONE OF NORTHERN MANITOBA AND KEEWATIN DISTRICT, CANADA
R . J . E . Brown, D i v i s i o n o f B u i l d i n g Research, N . R . C . , Ottawa, Canada. Mineral e x p l o r a t i o n i n Northern Manitoba and D i s t r i c t o f Keewatin and i n v e s t i g a t i o n s f o r a proposed n a t u r a l g a s p i p e l i n e have produced a need f o r perma- f r o s t i n f o r m a t i o n where v i r t u a l l y no d a t a were p r e v i o u s l y a v a i l a b l e . Thermocouple and t h e r m i s t o r c a b l e s have been i n s t a l l e d a t v a r i o u s d e p t h s down t o 1 5 m i n d i f f e r e n t t y p e s o f t e r r a i n i n t h i s r e g i o n . Ground temperatures recorded d u r i n g 1974-1976 i n c l u s i v e and t h e i r r e l a t i o n t o c l i m a t i c and t e r r a i n f a c t o r s a r e p r e s e n t e d . Annual v a r i a t i o n s i n ground temperatures and t h i c k n e s s o f t h e a c t i v e l a y e r i n
r e s p o n s e t o annual f l u c t u a t i o n s o f summer and w i n t e r a i r t e m p e r a t u r e s i n d i c a t e t h e i n f l u e n c e o f c l i m a t e on p e r m a f r o s t . Ground t e m p e r a t u r e s vary i n d i f f e r e n t t y p e s o f t e r r a i n a t one l o c a t i o n due t o v a r i a t i o n s i n v e g e t a t i o n , snow cover, p r o x i m i t y t o w a t e r b o d i e s , and type o f s o i l and r o c k .
/
INFLUENCE DU CLIMAT ET DU TERRAIN SUR LA TEMPERATURE DU SOL, DANS LA ZONE DE PERGE- LISOL CONTINU DU NOaD DU MANITOBA ET DU DISTRICT DE KEEWATIN, AU CANADA
R.J.E. Brown, D i v i s i o n d e s r e c h e r c h e s en Bstiment, C.N.R.C., Ottawa, Canada
Dans l e nord du Manitoba e t l e d i s t r i c t de Keewatin, l ' e x p l o r a t i o n m i n i s r e e t l e s e t u d e s r e l a t i v e s au p r o j e t de c o n s t r u c t i o n d ' u n gazoduc e x i g e n t l ' a p p o r t d ' i n f o r - mation s u r l e p e r g e l i s o l , a c t u e l l e m e n t presque i n e x i s t a n t e s . On a i n s t a l l 6 d e s c 8 b l e s d e thermocouples e t t h e r m i s t o r s b d i v e r s e s profondeurs, j u s q u ' z 1 5 m s t r e s , dans l e s d i v e r s t y p e s d e t e r r a i n de c e t t e r e g i o n . On donne i c i d e s r e l e v e s d e s t e m p e r a t u r e s du s o l , d e 1974 3 1976 i n c l u s , e t l ' o n i n d i q u e l e s r e l a t i o n s q u i e x i s t e n t e n t r e c e l l e s - c i e t l e s elements c l i m a t i q u e s e t morphologiques. Les v a r i a t i o n s a n n u e l l e s d e l a t e m p e r a t u r e du s o l e t d e l ' e p a i s s e u r du m o l l i s o l , q u i dependent d e s f l u c t u a t i o n s a n n u e l l e s d e s t e m p e r a t u r e s atmosph6riques d ' h i v e r e t d ' e t e , i n d i q u e n t l ' i n f l u e n c e du c l i m a t s u r l e p e r g e l i s o l . Les t e m p e r a t u r e s du s o l v a r i e n t dans l e s d i v e r s t y p e s d e t e r r a i n d'une r e g i o n donnge, en f o n c t i o n d e l a v e g e t a t i o n , d e l a c o u v e r t u r e n i v a l e , d e l a p r o x i m i t e d e p l a n s d ' e a u , e t d e s t y p e s d e s o l s e t d e r o c h e s .
BJIMRHME KJIMMATA M X A P A K T E P A MECTHOCTM HA T E M n E P A T Y P Y r P Y H T O B B 30HE
CllJIOUHOI'O P A C l l P O C T P A H E H M R M H O ~ O J I E T H E B M E P 3 J I O T b l B C B R 3 H C p a 3 B e J I ~ 0 a n o n e 3 ~ ~ x W C K O n a e m X B C e B e p ~ O f i M ~ H W T O ~ ~ W K W B ~ T W H ~ H p a 3 p a 6 0 ~ K o n n p o e K T a r a s o n p o ~ o ~ ~ a B 0 3 H H K n a H ~ O ~ X O J I W M O C T ~ ll0- JlYseHMR J I a H H H X 0 M H O r o n e ~ H e f i M e p s n o T e , K O T O p H e p a H e e I I p a K T W s e C K W O T C Y T - c T B o s a n u . H a p a 3 n u u ~ o f i r n y 6 1 4 ~ e
/zo
1 5 M / , B p a s n a s e ~ x T m a x M e c T H o c T x 3 T O r 0 p a R o ~ a 6 ~ n u y n o x e e H ~a6enkic
T e p M o n a p a M u a T e p M u c T o p a m . B A a H - HOR p a 6 o ~ e n p e x c T a B n e m T e M n e p a T y p H ~ P Y H T O B , 3 a p e r ~ c ~ p ~ p o ~ a ~ ~ ~ e B ne- Pl'iOa C 1 9 7 4 I?.no
1 9 7 6 r . BKJTIOVkiTenbHO, a T a K X e PIX 3 a B W C l i M O C T b O T KnW-M a T W s e C K H X Pi T O ~ O I ? ~ ~ @ W ~ ~ C K W X @ ~ K T O P O B . ~ 0 ~ 0 B H e K O n e 6 a H M R T e M n e p a T Y P H P P Y H T O B W' T O J l ~ H H h l J I e R T e n b H O r O c n o R B 3aBWCHMOCTH O T rOJIOBMX ~ o n e 6 a ~ H f i n e T H W X W 3HMHHX T e M n e p a T y p BOSJIYXa C B W J I e T e J I b C T B m T 0 BJIHRHWH K n W M a T a H a C O C T O R H H e M e p 3 n H x I ' p y H T O B . T e M l - I e p a ~ y p a I ' p y H T O B H a p a 3 n W n H H X T W n a X MeCTHOCTW B I I p e J I e J I a X O n H O r O p a R 0 H a M e H R e T C R B 3aBHCkiMOCTM O T P a C T H T e n b - H O C T H , C H e X H O r O n o K p o B a , 6 n W 3 0 C T H K BOJIH6IM 6 a ~ ~ e f i H a M W T W n a I I O s B H W r o p m x nopox.
INFLUENCE OF CLIMATE AND TERRAIN ON GROUND TEMPERATURES IN THE CONTINUOUS
PERMAFROST ZONE OF NORTHERN MANITOBA AND KEEWATIN DISTRICT, CANADA
R . J . E . Brown
D i v i s i o n of B u i l d i n g Research, National Research Council o f Canada, Ottawa, O n t a r i o .
INTRODUCTION
S i n c e 1973, r e g u l a r measurements o f ground t e m p e r a t u r e s have been t a k e n by t h e s t a f f o f t h e D i v i s i o n o f B u i l d i n g Research, N a t i o n a l Research Council o f Canada, a t v a r i o u s s i t e s i n n o r t h e r n Manitoba and D i s t r i c t o f Keewatin
( F i g . 1) t o a s s e s s t h e i n f l u e n c e o f c l i m a t e and t e r r a i n o n p e r m a f r o s t i n t h e s o u t h e r n r e a c h e s o f t h e continuous zone. V i r t u a l l y no i n f o r m a t i o n e x i s t e d on p e r m a f r o s t c o n d i t i o n s i n t h i s a r e a p r i o r t o t h e s e s t u d i e s . Limited d a t a on p e r m a f r o s t ground t e m p e r a t u r e s and r e l a t e d c o n d i t i o n s were o b t a i n e d f o r C h u r c h i l l , Manitoba i n t h e 1940's and 1 9 5 0 ' s d u r i n g c o n s t r u c t i o n o f s e v e r a l b u i l d i n g s ahd municipal s e r v i c e s
(Crumlish, 1947; Dickens and Gray, 1960) and a d r i l l i n g program c a r r i e d o u t by t h e Snow, I c e and Permafrost Research E s t a b l i s h m e n t (now t h e Cold Regions Research and Engineering Laboratory) of t h e United S t a t e s Army. The o n l y o t h e r i n f o r m a t i o n on perma- f r o s t c o n d i t i o n s r e s u l t e d from t h e o p e r a t i o n of a n i c k e l mine a t Rankin I n l e t , N.W.T., from 1957 t o 1962. Continuing mineral e x p l o r a t i o n and p i p e l i n e s i t e i n v e s t i g a t i o n s have i n c r e a s e d ' t h e need f o r i n f o r m a t i o n on p e r m a f r o s t , p a r t i c u l a r l y ground tem- p e r a t u r e s and t h e i r v a r i a b i l i t y i n d i f f e r e n t t y p e s o f t e r r a i n . The r e s u l t s o f o b s e r v a t i o n s through 1974- 1976 a r e r e p o r t e d i n t h i s p a p e r .
CLIMATIC AND TERRAIN CONDITIONS
TABLE I . CLIMATIC DATA AND SUMMER AND WINTER AVERAGE AIR TEMPERATURES FOR METEOROLOGICAL STATIONS IN STUDY AREA
S t a t i o n Latitude Mean Annual Air
Temperature, "C Mean Annual Maximum
Air Temperature. "C Mcan Annual M i ninlum
Air Temperature. O C I:rcczing 1 ndcx Degree Days, O C Thawing Index Degree Days. "C Mean Annual P r e c i p i t a t i o n , cm Mean Annual R a i n f a l l , cm Mean Annual Snowfall, cm Snow on ground, cm
(avg. max. snow cover) Avg. o f Mean Air Temp.
(.June - S e p t . ir1c1 . )
,
O CAvg. o f Mean Air Temp. (Oct. - May i n c l . ) , O C Churchill 5S0 45'N Ennadai Lake Chester- f i e l d Baker Lake 64O 18'N Keewatin and t h e n o r t h e a s t e r n p o r t i o n of Manitoba a r e s i t u a t e d i n t h e A r c t i c . C l i m a t o l o g i c a l d a t a f o r t h e s t u d y a r e a i n d i c a t e t h a t a i r tempera- t u r e s and p r e c i p i t a t i o n d e c r e a s e s t e a d i l y northward I
from t h e h i g h e s t v a l u e s a t C h u r c h i l l t o Baker Lake, N.W.T. (Table I )
.
The a v e r a g e s o f t h e mean a i r t e m p e r a t u r e s f o r June t o September i n c l u s i v e , andfcl I- (It- ~ - P ~ \ c I - I k> Fli~y i r ~ c l u s i ve f o r t h e y e a r s 1974 t o I!)?c> .IT t h c t.l)ul- s t a t i o n s nre given i n Table I . 5l111l1l1r.l. :I\.C\I.:IS~*S .I I . C I ~ i g l l ~ r a t Er~nadai Lake t h a n a t C h u r c h i l l because of t h e l a t t e r ' s p r o x i m i t y t o Hudson Bay and h i g h e r a t Baker Lake t h a n C h e s t e r f i e l d f o r t h e same reason.
D e t a i l s o f t h e t e r r a i n o f t h e s t u d y a r e a c a n b e found i n t h e two r e f e r e n c e s : Canada, 1962 and Canada, 1971.
The s t u d y a r e a l i e s i n t h e c o n t i n u o u s perma- f r o s t zone (Brown, 1967; Canada, 1971; Brown, 1977) ( F i g . 1 ) . C h u r c h i l l i s s i t u a t e d n e a r t h e a p p r o x i m t e l y known boundary between t h e c o n t i n - uous and d i s c o n t i n u o u s zones whero pernuifroc;t i s ;
about 60 m t h i c k . Near t h e c o a s t i t increasc:s t o approximately 270 m a t Rankin I n l e t (Weber and T e a l , 1959). I n l a n d s t h e p e r m a f r o s t i s t h i c k e r away from t h e thermal i n f l u e n c e o f Hudson Bay. I n t h e v i c i n i t y of Baker Lake, i t i s e s t i m a t e d t o be
approximately 500 m t h i c k . S u r f a c e f e a t u r e s normally a s s o c i a t e d w i t h t h e continuous permafrost zone a r e widespread. I c e wedge polygons and mudboils (non- s o r t e d c i r c l e s ) a r e t h e main forms o f p a t t e r n e d ground on l a n d . D i s t i n c t t y p e s of p a t t e r n e d ground e . g . , polygons, r i b - a n d - t r o u g h p a t t e r n s , a l s o o c c u r i n t h e shoal a r e a s o f t h e l a k e s ( S h i l t s and Dean, 1975)
.
METIIODS AND INSTRUMENTATION
I n 1972, 4 thermocouple c a b l e s were p l a c e d i n diamond d r i l l b o r e h o l e s i n bedrock, m a r i n e / t i l l , and an e s k e r a t Rankin I n l e t . Four s i m i l a r c a b l e s were i n s t a l l e d a t C h u r c h i l l i n 1973 i n bedrock, marine/
t i l l , and a p a l s a . The n e x t year, 4 were p l a c e d a t
Heninga Lake (bedrock and t h i n t i l l w i t h s o r t e d c i r c l e s , p o o r l y d r a i n e d t i l l w i t h sedge cover) and two i n t h e Maguse Lake r e g i o n ( t i l l ) , b o t h i n l a n d l o c a t i o n s . I n 1975 t h e P o l a r Gas P r o j e c t i n s t a l l e d t h e r m i s t o r c a b l e s f o r t h e a u t h o r a t 4 major r i v e r c r o s s i n g s on t h e proposed n a t u r a l gas p i p e l i n e r o u t e , one i n Manitoba on t h e N e j a n i l i n i River 160 km northwest o f C h u r c h i l l and one each a t : 100 km s o u t h o f Baker Lake on T h i r t y Mile Lake, 15 km west o f Baker Lake on Thelon River, and 100 krn n o r t h o f Baker Lake on Meadowbank R i v e r . I n t h e summer o f 1976 P o l a r Gas i n s t a l l e d 9 t h e r m i s t o r c a b l e s f o r t h e a u t h o r a l o n g t h e proposed p i p e l i n e r o u t e on h i g h e r ground away from t h e major r i v e r s of which 4 a r e i n t h e r e g i o n n e a r t h e Tha-Anne, Noomut, Kogtok and Kazan R i v e r s . Locations o f t h e s e c a b l e s a r e shown i n Fig. 1.
A l l thermocouple and t h e r m i s t o r c a b l e s were
f a b r i c a t e d t o a l e n g t h of approximately 15 m w i t h s e n s o r s a t d e p t h s of 0.76, 1.52, 2.29, 3.05, 3.81, 4.57, 6.10, 12.19, and 15.24m. Some c a b l e s were i n s t a l l e d t o t h e f u l l 15.24-m depth and t h e remainder t o s h a l l o w e r d e p t h s where d r i l l i n g d i f f i c u l t i e s were encountered o r t h e maximum h o l e depth f o r purposes o t h e r than t h i s s t u d y was o n l y r e q u i r e d t o r e a c h bedrock. The thermocouple c a b l e s were r e a d w i t h a battery-powered p o r t a b l e p r e c i s i o n p o t e n t i o m e t e r and t h e t h e r m i s t o r c a b l e s w i t h a battery-powered r e s i s t a n c e b r i d g e . The c a b l e s were u s u a l l y read monthly a t Rankin I n l e t and q u a r t e r l y a t C h u r c h i l l . The o t h e r c a b l e s a r e a c c e s s i b l e only by h e l i c o p t e r . Long d i s t a n c e s o v e r u n i n h a b i t e d t e r r a i n , uncer- t a i n weather c o n d i t i o n s and h i g h c o s t o f h e l i c o p t e r t r a v e l made i t d i f f i c u l t t o reach t h e i n l a n d s i t e s a t r e g u l a r 3-month i n t e r v a l s . S u f f i c i e n t observa- t i o n s have been made a t v a r i o u s s e a s o n s , however, t o g a i n an a p p r e c i a t i o n o f t h e ground temperature regime.
SITE CONDITIONS AND GROUND TEMPERATURES Information on c a b l e type and depth, s i t e condi- t i o n s i n c l u d i n g e l e v a t i o n above s e a l e v e l , geology, t h i c k n e s s o f o r g a n i c l a y e r , and e a r t h m a t e r i a l s i s p r e s e n t e d i n Table 11. Average bottom h o l e tempera- t u r e s compared w i t h mean annual a i r temperatures a r e shown i n Table 111, a s a r e v a r i a t i o n s i n t h e t h i c k - n e s s o f t h e a c t i v e l a y e r from year t o y e a r . Snow d e p t h and d e n s i t y measurements a r e given i n Table IV. Ground temperature i n f o r m a t i o n f o r t h e s i t e s i s given i n F i g s . 2 t o 8 .
RESULTS AND DISCUSSION
A l l t h e ground temperature c a b l e s i n t h e s t u d y
a r e a a r e s i t u a t e d i n t h e continuous p e r m a f r o s t zone. Ground temperatures g e n e r a l l y d e c r e a s e northward i n
response t o t h e i n c r e a s i n g l y s e v e r e a i r tempera- t u r e s . A t each l o c a t i o n t h e ground temperature ( a t t h e bottom o f t h e hole) i s s e v e r a l d e g r e e s warmer than t h e mean annual a i r temperature. (The v a r i a - t i o n i n t h e s e d i f f e r e n c e s from one s i t e t o a n o t h e r i s due t o l o c a l t e r r a i n c o n d i t i o n s (Table 1 1 1 ) ) .
The i n f l u e n c e o f a i r temperature v a r i a t i o n s from year t o y e a r on ground t e m p e r a t u r e s i s exem- ~ l i f i e d a t t h e s e l e c t e d d e u t h s i n F i n s . 4 and 5 ;or C h u r c h i l l and Rankin ~ k l e t , r e s p e c t i v e l y . The i n f l u e n c e o f c o o l e r average summer a i r t e m p e r a t u r e s i n 1974 compared with 1975 and 1976 (Table I ) i s r e f l e c t e d i n t h e ground t e m p e r a t u r e s . The 1976 summer was c o o l e r t h a n 1975 a t Rankin I n l e t ( C h e s t e r f i e l d ) , b u t t h e ground t e m p e r a t u r e s q e r e s i m i l a r t o t h o s e i n 1975. Winter a i r t e m p e r a t u r e s have a comparable e f f e c t although v a r i a t i o n s i n snow cover from y e a r t o y e a r complicate t h i s
c l i m a t i c e f f e c t . The w i n t e r o f 1974-75 was s l i g h t l y m i l d e r than t h e one preceding and t h e one f o l l o w i n g which shows up p a r t i c u l a r l y a t Rankin I n l e t ( F i g .
5 ) . The same p a t t e r n does n o t emerge a t C h u r c h i l l although t h e warmer ground t e m p e r a t u r e s d u r i n g t h e following summer o f 1975 a t t h e 14.63-m depth r e s u l t p a r t i a l l y from t h e previous milder w i n t e r .
A t Heninga and Maguse Lakes t h e ground t e m p e r a t u r e s
recorded i n September of 1975 and 1976 were 1 / 2 t o 1 C deg warmer t h a n t h o s e i n 1974. The 3 h o l e s i n t h e n o r t h e r n reaches o f t h e s t u d y a r e a ( T h i r t y Mile Lake, Thelon River and Meadowbank River) e x p e r i - enced warmer ground temperatures i n September 1975 than i n 1976 ( F i g . 8) f o l l o w i n g t h e t r e n d o f t h e corresponding summer a i r t e m p e r a t u r e s a t Baker Lake (Table I ) . Ground t e m p e r a t u r e s a t t h e
N e j a n i l i n i River i n t h e s o u t h showed t h e same p a t - t e r n although summer a i r t e m p e r a t u r e s a t C h u r c h i l l and Ennadai Lake i n t h e same r e g i o n were warmer i n 1976.
The t h i c k n e s s o f t h e a c t i v e l a y e r a l s o v a r i e d from year t o y e a r i n response t o f l u c t u a t i o n s i n summer a i r t e m p e r a t u r e s (Table 111). I t i s most n o t i c e a b l e i n t h e bedrock s i t e s a t C h u r c h i l l and Rankin I n l e t . A t Rankin I n l e t t h e t h i c k e s t a c t i v e l a y e r o c c u r r e d i n 1975, t h e warmest summer. The same p a t t e r n s a r e g e n e r a l l y n o t i c e a b l e a t t h e o t h e r c a b l e s i t e s a t C h u r c h i l l and Rankin i n l e t , b u t anomalies occur probably because o f v a r i a t i o n s i n ground moisture c o n t e n t a t t h e s e mineral s o i l s i t e s . The t h i c k n e s s o f t h e a c t i v e l a y e r a t t h e Heninga Lake s i t e was s i g n i f i c a n t l y g r e a t e r i n t h e warmer summers of 1975 and 1976 t h a n 1974. I n t h e n o r t h t h e a c t i v e l a y e r a t T h i r t y Mile Lake was t h i c k e r i n 1975 than i n 1976 ( F i g . 8 ) .
The p r i n c i p a l t e r r a i n f a c t o r 5 a f f e c t i n g t h e eround temverature regime a t t h e s i t e s i n c l u d e
"
-
v e g e t a t i o n and p e a t cover, snow cover, p r o x i m i t y t o w a t e r b o d i e s , and type of s o i l o r r o c k . The range of ground temperature regimes can b e s e e n I n F i g s . 2, 3, 6, 7.
A t C h u r c h i l l t h e bedrock s i t e shows much g r e a t e r
annual temperature f l u c t u a t i o n s and a lower annual mean than t h e t h r e e mineral s o i l s i t e s mainly because o f t h e h i g h e r thermal c o n d u c t i v i t y (about
7w/m2) ( F i g s . 2 and 4)
.
The amplitude o f bottom h o l e temperatures i s a b o u t 3 C deg i n t h e rock compared w i t h 1 C deg f o r t h e o t h e r h o l e s . 'The i n c r e a s e of mean annual temperatures i n t h e l a t t e r t h r e e h o l e s from t h e marine/ t i l l through t h e p a l s a t o t h e p a l s a d e p r e s s i o n corresponds t o an i n c r e a s e i n p e a t t h i c k n e s s and snow cover and d e c r e a s e i nTABLE 11. CABLE SITES: CABLE DEPTH AND SITE CONDITIONS
Ground
Cable Cable Surface Geology Organic Earth Materials
Location Type* Depth, Elev. (Landform) Layer. (Mineral Soil)
m ASL, m cm Churchill 1. 2. 3. 4. Nil Quartzite 2 3 Silt-Clay-Stones 38 154 Tcpl Tcpl Tcpl Tcpl Bedrock Marine/till** Palsa Palsa depression Rankin Inlet 1. 2. 3. 4. Tcpl Tcpl Tcpl Tcpl Bedrock Esker Till Esker Nil Greenstone 5 Gravel 8 Silt-Clay-Stones 15 Grave 1 Heninga Lake 1 . Thin till- . bedrock Till Till Nil ) Silt-Clay-Stones ) -Granite Gneiss 3 8 10 Tcpl Tcpl Tcpl Maguse Lake 1. 2. Tcpl Tcpl Till Till 36 Sand-Silt-Stones 36 Nejanilini River l'ha-Anne Rivcr Noomut River Kogtok River Kazan River Thirty Mile Lake Thelon River Meadowbank River Thmr Thmr Thmr Thmr Thmr Thmr Thmr Thmr Glacial dclta Outwash Marine/till Till Marineltill Till Nil Sand 8 Silt-Sand 2 3 25 Sand-Silt-Stones 5 10 10 Nil Sand-Stones -. --
* Tcpl - thermocouple cable; Thmr - thermistor cable * * Marine dcposits overlying till
TABLE I11 CABLE SITES: AIR AND GROUND TEMPERATURES AND THICKNESS OF ACTIVE LAYER
THICKNESS OF ACTIVE LAYER, cm Location
Mean Annual Avg. Bottom
Air Temp. , OC Hole Temp. , OC 1974 1975 19 76
-
Churchill 1. - 7.3 2.-
7.3 3. - 7.3 4.-
7.3 Rankin Inlet 1. - 11.6 2 . -11.6 3. -11.6 4. -11.6 Heninga Lake 1.-
9.7 (approx.) -6.1 290 34 1 ? . - 9.7 (approx.) -6 -4 2 16 287 3. - 9.7 (approx.) -4.9 158 174 4. - 9.7 (approx.) -5.6 104 146 Maguse Lake1.
-
9.7 (approx. ) -4.7 - 38 (peat) -38 (peat)2. - 9.7 (approx.) -5.1
-
91 (bare soil) -91 (bare soil)Nejanilini River
Tha- Anne River
Noomut River Kogtok IRivcr
Euzun River Thirty Mile Lake Thelon River Meadowbank Rivcr - 7.5 (approx.) - 9.4 (appmx.)
-
9.7 (approx.) -10.3 (approx.) -11.7 (approx.) -12.0 (approx.) -12.5 (approx.) -12.8 (approx.) Hole depth' (75-6) 6 1 31 51 111 204 75-
30TABLE IV. SNOW DEP'III, cm AND DENSITY, gm/cc
1974 1975 1976
Locat i o n March Dec
.
March Dec . March Dec.
Dep. Dens. Dep. Dens. Dep. Dens. Dep. Dens. Dep. Dens. Dep. Dens.
C h u r c h i l l 1 . 6 1 . 2 3 7 38 . 3 0 8 51 . 3 2 0 3 - 20 , 2 6 4 15 . 2 8 0 2 . 4 6 . 2 7 0 18 , 2 5 7 36 . 3 1 2 10
-
3 3 . 3 4 7 10 . 2 4 0 3 . 56 . 2 2 7 36 . I 9 6 53 . 2 3 2 20-
38 . 2 2 0 38 . 2 5 2 4 . 6 9 . 2 3 5 56 . 2 1 0 102 . 2 4 5 25-
58 . I 9 2 41 . 2 2 0 Rankin I n l e t 1 . 0 - 10 . 3 0 8 0 - 3 . 3 2 0 8 . 3 6 0 2 . 8 - 2 3 , 2 2 0 30-
8 . 2 5 6 10 . 3 2 0 3 . 15 - 20 . 2 8 7 15 - 15 - 15 , 3 6 0 5 - 4 . 2 3 . 2 7 7 94 . 3 6 7 8 1 . 3 7 6 9 9-
91 . 3 2 0 4 6 . 3 2 0 Heninga Lake Maguse Lake 1 .-
6 9 . 2 2 0 46 , 3 1 3 2 . 41 . 2 6 4 23 , 2 4 0 N e j a n i l i n i R i v e r-
0 - T h i r t y M i l e Lake - - - 41 . 4 0 0-
Thelon R i v e r 28 . 2 8 1-
Meadowbank ~ l v e r-
5 1 . 4 0 9-
snow d e n s i t y . The t h i c k e r p e a t c o v e r on t h e p a l s a r e s u l t s i n a t h i n n e r a c t i v e l a y e r than a t t h e m a r i n e / t i l l s i t e . The absence o f permafrost i n t h e p a l s a d e p r e s s i o n down t o 1 5 m i s probably r e l a t e d t o t h e swampy c o n d i t i o n s and enhanced by t h e t h i c k snow c o v e r . The s t e a d y temperature decrease down- ward i n d i c a t e s t h a t p e r m a f r o s t probably e x i s t s below a thaw b a s i n , beginning a t a depth o f approximately 30 t o 40 m.The s i t u a t i o n a t Rankin I n l e t i s s i m i l a r where t h e annual temperature f l u c t u a t i o n s a r e approxima- t e l y 2 C deg a t t h e bottom o f t h e bedrock h o l e (thermal c o n d u c t i v i t y 2.5 t o 5 w/m2) and 1.5 C deg i n t h e e s k e r g r a v e l ( F i g s . 3 and 5 ) . Temperature f l u c t u a t i o n s i n t h e Rankin I n l e t bedrock h o l e a r e l e s s than t h e C h u r c h i l l bedrock h o l e , because o f lower thermal c o n d u c t i v i t y . Mean annual tempera- t u r e s and f l u c t u a t i o n s a r e almost a s g r e a t i n t h e e s k e r g r a v e l and t i l l a s i n t h e bedrock because o f t h e t h i n p e a t l a y e r and t h i n snow c o v e r . The mean a n n u a l ground temperature of c a b l e No. 4 i s 1 . 5 C deg h i g h e r t h a n t h e o t h e r s because o f t h e much t h i c k e r snow c o v e r .
A t Heninga Lake, c a b l e s Nos. 1 and 2 have g r e a t e r annual temperature amplitudes and lower means t h a n c a b l e s Nos. 3 and 4 because t h e y a r e l o c a t e d i n bed- rock w i t h a t h i n till cover and t h i n n e r p e a t l a y e r s
( F i g . 6 ) . Temperatures i n t h e l a t t e r two h o l e s a r e modified b y t h e i r p r o x i m i t y t o t h e l a k e . Cable No. 1
a t Maguse Lake has a s l i g h t l y warmer temperature regime than No. 2 because i t i s n e a r e r t h e l a k e and has t h i c k e r snow c o v e r ( F i g . 7 ) .
The 8 t h e r m i s t o r c a b l e s on t h e p i p e l i n e r o u t e a r e a1 1 c o n s i d e r a b l y a f f e c t e d by l o c a l t e r r a i n c o n d i t i o n s ( F i g . 8 ) . The c a b l e a t t h e N e j a n i l i n i River i s n o t i n p e r m a f r o s t b u t i t experiences a
tremendous annual temperature f l u c t u a t i o n
.
I t i s l o c a t e d a t t h e t o p of a s t e e p sandy s o u t h - f a c i n g r i v e r bank. The sandy s o i l has a v e r y low moisture c o n t e n t and t h i s combined w i t h v i r t u a l l y no snow accumulation i n t h e w i n t e r r e s u l t s i n deep s e a s o n a l f r e e z i n g which completely thaws each summer. Con- t i n u o u s p e r m a f r o s t probably e x i s t s away from t h e bank. Tile c a b l e s a t T h i r t y Mile Lake, Thelon Riverand Meadowbank River e x h i b i t t e m p e r a t u r e s c o n s i - d e r a b l y warmer i n r e l a t i o n t o t h e mean annual a i r temperatures mainly because o f t h e i r p r o x i m i t y t o b o d i e s o f water and r e l a t i v e l y t h i c k snow cover
(Table 111)
.
The Meadowbank River c a b l e i s a t t h e w a t e r ' s edge and i s a c t u a l l y submerged d u r i n g s p r i n g breakup t h u s t h e temperatures a r e g r e a t 1 y modified. ' h e Kazan River c a b l e , l o c a t e d on a h i l l t o p s e v e r a l k i l o m e t r e s from t h e r i v e r and w i t h o n l y 5 cm o f p e a t , shows t h e s m a l l e s t d i f f e r e n c ei n ground t e m p e r a t u r e s from t h e mean annual a i r
temperature (Table 111)
.
CONCLUSIONS
Ground temperature measurements d u r i n g t h e p e r i o d 1974 t o 1976 i n c l u s i v e i n d i c a t e t h a t some c o r r e l a t i o n s e x i s t between them and t h e c l i m a t i c and t e r r a i n f a c t o r s . These r e l a t i o n s h i p s have shown up i n o t h e r a r e a s s t u d i e d p r e v i o u s l y
i n c l u d i n g Thompson, Manitoba, Yellowknife, N.W.T.
and Devon I s l a n d (Brown, 1973)
.
A t a l l t h e s e l o c a t i o n s , v a r i a t i o n s i n a i r temperature from y e a r t o y e a r r e s u l t i n corresponding f l u c t u a t i o n s i n ground temperatures and t h i c k n e s s o f t h e a c t i v e l a y e r . Local d i f f e r e n c e s i n t e r r a i n c o n d i t i o n s , i n c l u d i n g t h i c k n e s s o f o r g a n i c l a y e r , snow cover, p r o x i m i t y t o w a t e r b o d i e s and type o f s o i l and r o c k , c o n t r i b u t e t o a range o f d i f f e r e n t groundtemperature regimes w i t h i n one l o c a l i t y . Exceptions and anomalies o c c u r which defy e x p l a n a t i o n .
D i f f i c u l t i e s a r i s e i n determining t h e q u a n t i t a t i v e i n f l u e n c e o f i n d i v i d u a l c l i m a t i c and t e r r a i n f a c t o r s . N e v e r t h e l e s s , c o n t i n u i n g o b s e r v a t i o n s a t e x i s t i n g s i t e s and i n s t a l l a t i o n o f c a b l e s a t new s i t e s w i l l improve t h e a b i l i t y t o e s t a b l i s h t h e s e ACKNOWLEDGEMENTS The a u t h o r g r a t e f u l l y acknowledges t h e a s s i s - t a n c e o f t h e f o l l o w i n g o r g a n i z a t i o n s d u r i n g t h e s e i n v e s t i g a t i o n s : National Research Council o f Canada, Ottawa, a t Thompson and C h u r c h i l l ; E a r t h Physics
Branch, Department of Energy, Mines and Resources, Ottawa; P o l a r Gas P r o j e c t , Toronto; E.B.A. Engineer-
i n g C o n s u l t a n t s Limited, Edmonton; J . D . Mollard and A s s o c i a t e s Limited, Regina; A r c t i c Research and T r a i n i n g Centre, Rankin I n l e t , N.W.T.; and Lambair Limited, Thompson.
T h i s paper i s a c o n t r i b u t i o n from t h e D i v i s i o n o f Building Research, National Research Council o f Canada and i s p u b l i s h e d w i t h t h e approval o f t h e D i r e c t o r o f t h e Division
REFERENCES
BROWN, R . J . E . 1967. Permafrost i n Canada. Map p u b l i s h e d by Div. o f Bldg. Res., Nat. Res. Council Canada (NRC 9769) and Geol. S u r v . of Canada (Map 1246A).
I O 0 " W 9 5 " W 90"W 1 0 0 W I 5 W PO' W - - -
-
G R O U N D T E M P E R A T U R E C A B L E-
M E A N A N N U A L A I R I S O T H E R M . ' C-
S O U T H E R N L I M I T OF C O N T I N U O U S P E R M A F R O S T Z O N E -Fig. I Permafmst ground temperature cables in northern Manitoba and District of Keenatin, Canada.
BROWN, R . J . E . 1973. I n f l u e n c e o f C l i m a t i c and T e r r a i n F a c t o r s on Ground Temperatures a t Three Locations i n t h e Permafrost Region o f Canada. North American C o n t r i b u t i o n t o t h e Second I n t e r - n a t i o n a l Conference on Permafrost, pp
.
2 7- 34. BROWN, R.J.E. 1977. Permafmst Map. HydrologicalA t l a s o f Canada, Can. Corn. I n t e r n . Hydrol. Decade.
CANADA, 1962. Geological Map o f Canada. Dept. Mines and Technical Surveys.
CANADA, 1971. The National A t l a s of Canada. Dept.
o f Energy, Mines and Resources; Map 11-12
(Permafrost), Map 41-42 ( S o i l s ) , Map 45-46 (Vegetation)
.
CRUMLISH, W.S. 1947. E x p l o r a t o r y Well D r i l l i n g i n Permafrost; Fort C h u r c h i l l , Manitoba, Canada, J u l y
-
November 1947. Rept. 1045, U.S. Engg. Res. and Development Lab.,
77 p .DICKENS, H . B . and GRAY, D.M. 1960. Experience w i t h a Pier-Supported B u i l d i n g o v e r Permafrost a t C h u r c h i l l , Manitoba. J. S o i l Mechanics and Foundation Div., Proc. Am. Soc. Civ. Engineers 86, SM 5, pp. 1-14.
SHILTS, W.W. and DEAN, W.E. 1975, Permafrost F e a t u r e s under A r c t i c Lakes, D i s t r i c t o f Keewatin, Northwest T e r r i t o r i e s . Can. J . E a r t h S c i . 12, pp. 649-662.
WEBER, W.W. and TEAL, S.S. 1959. A S u b - a r c t i c Mining Operation. Can. Mining and M e t a l l u r g i c a l B u l l . 62, p . 252-256. TEMPERATURE. ' C Man anniial air tmpcntun -7.3 I5
-
'
Fig. 2 Churchill, Manitoba: mean annual ground temperature and maximum-minimum envelopes for 1974-76 incl.
TEMPERATURE, r E x
-
L m-
1. Bedrock --- 2. Erker 1. 1111 4 . Esker-
Fig 3 Rankin Inlet, N.W.T.: mean annual ground temperature and maximum-minimum envelopes for 1974-76 incl.
TEMPERATURE. C 1. Bedrock 2. MarinelTill
~~g$~5~gsg
-
1. Bedrock-
PI PI I-
1. Bedrock ----
2. MarinelTill 3. Pal- 4. Palsa depression (c) Fig. 4 Ground temperatures at Churchill. Manitoba,1974-76 incl. at depths of: 1.07 m (A);
4.27 m (B); and 14.63 rn IC).
1. Bedrock' 2. Esker
2ot,
-
3.,
Till, ,
,
,
:Bi
..-.. 4. Esker
-
2s-
1. Bedrock( C )
I
F i g 5 Ground temperaturesat Rankin Inlet. N.W.T.1974-76 incl. at depths of: 1.07 m (A); 4.27 m (B);
and 13.22 m (C).
Fig. 6 Heninga Lake. N.W.T.: maximum-minimum ground temperature envelopes based on observations i n 1974-76 incl.
TEMPERATURE, "C
- 2 0 -15 - 1 0 - 5 0 5
1. Till 2. Till
Fig. 7 Maguse Lake, N.W.T.: maximum-minimum ground temperature envelopes based on observations i n 1975 and 1976.
TEMPERATURE. 'C
Fig. 8 Polar Gas Pipeline cables: ground temperature observations for
