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Home , Colville River (Alaska), Drainage basin, Horton River (Canada), Northern Sea Route, Yana (river), Yenisey Gulf

Plate 1. The Colville basin, which is approximat ely 100 tim es th e size of its delta, covers 29% of the North ern Slope of . Unlike the larger dr ainage basin s in th e , that of th e Colville is entire ly confined to th e zone of cont inuos permafrost . Du ring floodin g, th e sa line wate r th at has intruded into th e cha nnels is flushed out and a freshwater wedge is creat ed in the ocean in front of th e delta. Journal of Coastal Research 718-738 Royal Palm Beach, Florida Summer 1998

Arctic Deltas H. Jesse Walker

Department of Geography State University Baton Rouge, LA 70803, U.S.A.

ABSTRACT_•••••••••••••••••••••••••••_ WALKER, H.J., 1998. Arctic Deltas. Journal of Coastal Research, 14(3),718-738. Royal Palm Beach (Florida), ISSN ,tllllllll:. 0749-0208. ~ ~. Arctic river deltas are among the most unique and fragile of deltas to be found on earth. Leading to this uniqueness ~ ~ and fragility are the interactions between geologic, oceanographic, climatologic, biologic, and cryospheric activities c+ &__7t' that occur in high latitudes. These interactions are analyzed at both regional and local levels with respect to their influence on delta formation. Specific morphological forms, such as -wedge polygons, and processes, such as ther­ moerosion, that are associated with permafrost are identified. Arctic deltas, including the , , , Mac­ kenzie, and Colville, are discussed illustrating the diverse range of variables affecting deltaic processes. Vari­ ables considered include age, size, shape, , load and surface forms. anthropogenicimpacts on deltaic , such as construction associated with hydrocarbon production, are considered as is the potential for change that could result from a rising sea level.

ADDITIONAL INDEX WORDS: Arctic, Alaska, , , coastline, deltas, deltaic processes, permafrost.

INTRODUCTION Eurasian Continents range in distance from the by 650 km in northern to about 2500 km in west­ Delt as are among th e most dyn amic and complex natural ern Canada and eastern . Across these continents flow phenomena on ea rth. Their dynamism stems from the fact a number of (Figure 1, insert A), many of which have th at they are the result of interactions between various ele­ formed deltas where they empty into the or its ments of the , lithosphere, atmosphere, bio­ bordering seas. The general courses of these rivers is deter­ sphere and, in high latitudes, the cryosphere. In addition, mined by the structure of the cont inents (Figure 1, insert B). most present-day deltas have been impacted heavily by hu ­ mans and, in the process, many deltaic forms and processes The have been altered. Of the world's deltas least modified by humans, those in The structure of the Arctic has been described as being the Arctic stand out. However, even some of those deltas are nearly symmetrical about the Arctic Basin (OSTENSO, 1968; being affected today because of the exploitation of various SATER et al., 1971; STEARNS, 1965). It has often been said resources, development of arctic navigation, im­ that the Arctic is "anchored" by three Precambrian shields, provements in technology, and a political climate that fosters one of each located in Canada-Greenland, Scandinavia and arctic activities. north-central Siberia (Figure 1, insert B). These sh ields are This ess ay, which is devoted to arctic deltas, first summa­ separate d by , plateaus and plains of younger and rizes the various geologic, oceanographic, climatologic, biolog­ varied origin. All of these structural units influ en ce the ar­ ic and cryospheri c activities that establish the environmental rangement of the drainage basins that are prevalent in the setting for arctic deltas in gen eral. Thi s section is followed by Arcti c today. As GORDEEV, et aZ. (1996) note:".. . the East­ a discussion of the various forms present and the various pro­ European and Siberian platform and the folded areas . .. are cesses operating in arctic deltas. A third part is a brief de­ composed of terrigenous, carbonate, chemogenic, and volcanic scription of several of the deltas found in the Arctic. It is sedimentary rocks from the Archean to the Quaternary age ." followed by a section about how humans are impacting arctic Added to this complex are various extensive evaporites that deltas, and finally there is a brief discussion about the future increase the diversity of materials transported to the deltas. of arctic deltas . In contrast, the Yukon and Mackenzie Rivers flow through highly erodible materials and, as a result, have suspended Regional Setting load s many times the amount of Siberian rivers.

The Arctic Ocean, the sma llest of the world's oceans, with The Sea an area of about 14 X 106 km", is nearly landlocked. Although it surrounds the North Pole, th e bordering American and The Arctic Ocean, similar to the other oceans, has deep central portions bordered by continental shelves. However, in the case of the Arctic Ocean, the continental shelves, into 98138 received and accepted in revision 9 May 1998. which the rivers of the adjoining continents drain, equals 720 Walker

THE ARCTIC A. DRAINAGE B. BASIC STR UCTURE

C. SEA ICE D. PERMAFROST

Figure 1. The Arctic. (A) Arctic Drainage. (B) Basic Structur e: 1. Sh ields, 2. Plains and Plat eau s, 3. Fold Mountains. After SATERet al. (1971). (C) Sea Ice: 1. Average minimum extent (summer), 2. Average maximum extent (winte r). After Sa ter et al. (1971). (0) Perm afrost: 1. Contine nta l Sh elf, 2. Conti nuous, 3. Discontinuous. After Pewe (1983). about one-third of the total ocean area. These shelves vary in that flows through it from th e is rel­ width from only a few lOs of km off Greenland and western atively warm and highly saline. As it moves into and Canada to more than 900 km in the . Because of through th e Arctic Ocean it affects sea-ice formation and these extensive shelves, th e volume of th e Arctic Ocean is less climatic conditions. The in the Arctic Ocean in relation to its area than that of the other oceans. The shal­ is also modified by seasonal events such as the freshening low over these exte ns ive shelves are conveni ently di­ that occurs from sea-ice melting and the influx of large vol­ vided into six seas because of the positions of several of the umes of from the land, especially Siberia Arctic Ocean's islands and a few continental ind entations. (WALKE R, 1992 ). They include the Barents Sea, the into which flows At th e present time in geologic history, sea ice (Figure 1, the Yeni sey, th e with the Lena, the Ea st Siberian insert C) dominates the Arctic Ocean. Its cover, which aver­ Sea with th e Kolyma, the Chuckchi Sea, and the ages 2 to 3 m thick, ranges from about 8 X 106 km 2 before with the Yukon River (Figure 2). The so-called , freeze-up (August) to 14 X 106 km 2 at its maximum extent into which the flows, is unlike th e other seas (Februa ry and March). During its maximum extent, all arctic because it has a very narrow shelf and is essentially a part deltas are ice-bound, a condition th at usu ally lasts for seven of the Canada Basin. to nine months. It is a length of time th at is shorter than for Although the Arctic Ocean has a number of connections other coastal situations becau se of th e discharge of relatively to th e south, all but one- the Strait-are sh allow . The warm water from inland th at speeds sea-ice melt. The sub-

Jo urna l of Coast al Resear ch, Vol. 14, No.3, 1998 Arcti c Delt as 721

RIVERS SEAS 1. Olenek A Beaufort 2. Kolyma B Chukchi 3. Lena 4. Khatanga C Bering 5. Indigrika D East Siberian 6. Yana E Laptev 7. Dubawnt F Kara 8. Anadyr G Barents 9. Bock H Norwegian 10. Anabar I Greenland 11. Pyosino 12. Cappermine J Hudson 13. Yenisei 14. Colville 15. Mackenz ie 16. Ob-irrysh 17. Churchill 18. Nelson 19. Severn 20. Yukon 21. Pechora 22 . Albany 23 . Dvina

Figure 2. The Arctic Ocean and adjacent land areas with the distribu tion of rivers, seas, per mafrost, ocean currents and ti des . Compiled from num erous sources including NOAA (1981 ), Lewis (1982), Pewe (1983 ) and Walk er (1992). aqueous portions of deltas are likely to hav e bottom-fast ice that is sufficiently low to insure th at all surface water freezes and may support numerous pressure . and remains frozen for up to nine months. In much of th e One of th e characteristics of sea ice in th e Arctic Ocean is Arcti c the depth of annua l freezing in , rivers and th e th e ". .. almost constant drift and deformation"(HIBLER, sea reaches two or more meters. 1989) caused by winds and ocean currents . Hibl er further , which primarily occurs as snow over most of notes th at the". .. magnitude of this interaction is especially th e Arctic, tends to be minimal. However , becau se of th e long pronounced near th e coast . .."(1989). Thus, ocean curre nts, period oflow temp erature, it remains on the surface for man y often enha nced by wave action, move ice floes into shallow months. Becau se snow is an insulator, th e timing of occur­ waters along th e coast including deltas. The keels of th ese rence and thickness of accumulation affects th e thickness of floes can cau se deep gouges in th e offshore (REIM­ th e ice th at forms on water bodies. Whereas the area west of NITZ et al., 1974). th e Mountains, which is under th e influ ence of Atlantic The tides along th e open coast s of the Arctic Ocean are air masses, has more than 500 mm of precipitation, eas t of genera lly small, ranging from appproximately 10 ern in th e that ran ge precipitation decreases to as little as to more tha n two met ers in the Bering Sea 100 mm near th e Kara, Laptev and Ea st Siberian coasts . Far­ (Figure 2). Major exceptions to th ese genera lly low tid es occur ther east it again increases becau se of th e influence of th e ill such locations as Hud son Strait and the where Pacific (GORDEEV et al, 1996). : tides of more th an seven meters are common. Becau se river discharge is dependent on precipitation amounts, th e quantity th at falls over specific basins is criti­ Weather and Climate cal. The averages, as calculated by BRYAZGIN (1979), in Arctic deltas, which occur at the interface between land cma " , from west to east, are: basin (129), and sea, sha re the climati c condit ions of both . Many of them Barents Sea basin (74), Kara Sea basin (53), Laptev Sea ba­ are also affected, even if indirectly, by th e climatic conditions sin (46), Ea st Siberian Sea basin (39), Chukchi basin (42), of the interior, conditions that are transferred to deltas by and Beaufort Sea basin (43). river flow. One of th e most import ant as pects of climate is Although temp erature and snowfall may be th e two most th e great seasonal variation of temp erature: temp erature important climatic elements in the Arctic, wind serves as an

J ournal of Coastal Resear ch, Vol. 14, No.3, 1998 722 Walk er

RIVER LENGTH AND PERMAFROST Rivers 1.Olenek 2. Kolyma 3. Lena 4. Khatanga 5. 6. Yana ContinuousPermafrost 7. Dubawnt @k:nHMW&Wl 8. An adyr Discontinuous Permafrost 9. Back No Permafrost 10. Anabar t;==--=--=--=::J 11. Pyasina 12. Coppermine 13. Yen isei 14. Co lville 15. Mackenzie 16. Ob - 17. Ch urchill 18. Nelson 19. Severn 20. Yuko n 21. Percho ra 22.Albany 23. Dvina o 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Length in Km .

Figure 3. Length of rivers in th e Arctic arranged by lengths in perm afrost (see Figure 2).

agent causing snow drifting, sea-ice drifting, silt transport tures) and low percolation rates (because of permafrost), in­ and storm-wave generation, all of which are important to del­ sure that and deltas are wat ery environments taic morphology. during th e summer season.

Drainage Basins and Rivers DELTAIC ENVIRONMENTS AND PROCESSES Arctic rivers, without which there would be no deltas bor­ Present-day deltas in the Arctic range in size from ex­ dering the Arctic Ocean , are highly varied in length, dis­ tremely small te.g., those forming in recently tapped deltaic charge, sediment load, and flooding characteristics. This is lakes ) to as large as 32,000 km 2 in the case of th e Lena River also true of the size, shape, and composition of the deltas that delta (Table 1). They also range in age from those newly some of these rivers hav e formed. The area of the Arctic formed to those that began forming as the rate of sea level Ocean is only 40% as large as the continental area drained rise began decreasing - 5000 BP (KOROTAYEV, 1986). Thus, into it , which is just the reverse of the ratio for the world as geologically speaking, all arctic deltas, similar to marine del­ a whole. With a drainage base that ranges from 48° N (nearly tas elsewhere in th e world, are young. halfway from the North Pole to the Equator) to 82° N (Figure Nonetheless, most arctic deltas have had sufficient time to 2), it is not surprising that 4 of the 12 longest rivers on earth develop most of the features that are typical of non-arctic dr ain into the Arctic Ocean. With such a wide latitudinal deltas, such as , abandoned channels, , range, these rivers originate in and drain through vegetation bars, , sand and lakes. However, many zones that include steppe grass, (especially taiga) and also possess forms that are unique to the Arctic, including ice and climatic zones that include desert, steppe, mi­ wedges, ice-wedge polygons, pingo s and thermokarst lakes. crothermal and tundra types. One of the most important conditions affecting arctic rivers The Seasons is permafrost (Figure 1, insert D, and Figure 3). Permafrost, which is present over one-fifth of the earth's land surface, is During most of the year, arctic deltas are in what might be discontinuous in its more southerly locations and continuous called a "dormant" state. Winter is long (Figure 4); all water in higher latitudes. Those rivers originating in the zone of bodies are frozen to depths of 1.5 to 3 m and ground water is continuous permafrost (such as the Colville and Kolyma) immobilized. Thus, little geomorphic activity can transpire. have zero or minimal flow during winter, whereas those orig­ The major exception is frost cracking that may occur with inating outside the zone of permafrost (such as the Mackenzie temperature change in sediments that are not well insulated and Lena) flow (although at reduced rates in sub-ice chan­ by snow. Snow forms, such as sastrugi, which develop on the nels) throughout the winter (WALKER, 1994a). snow surface because of wind, are ephemeral and disappear Because much of the Arctic has gentle-sloping and with . is low lying, many rivers have wide floodplains. They are of­ Such a state lasts until May-June when air temperature ten multi-channeled and braided. Such conditions, when com­ rises to a point when snowmelt begins. Melt water then flows bined with low evaporation rates (because of low tempera- from the surface to the river channels and then downstream.

Journal of Coas ta l Research, Vol. 14, No.3, 1998 Arctic Deltas 723

APPR OXIWATE '52A:'lON INITIAT ED BY CH AR ACT ERIS TIC S DU R AT ION

WINTU ..."UIANCE Of A :u WilKS SOLID ,e, COVEl EA.'LV DISCHAIOE UNDEI Ie, TO OCIAN LATI .0 DISCHARGE UNDII ICI TO OCIAN C\JO t.O O ...... c'o "'d' ...... OOMLQo,)C'1C'l te ...... O":l ""d"MM ....-lC"';)C"'JC":) OM "'d'C'OOO C'l .....-l ...... C"':! OO SPllNo APPUIANCE Of 3 WilKS MELT-WAUl , .. - III"lU' SHOW MELT-WAUl ACCUMULATING ON A.D flOWING 0'111 AND UMDn ICI InAltU' UMO"AL Of Ict flOM 11'111 ,on- IIIA,ttU' FlOODINO .OLLOWINO IIIAII:U'

SUMMEI END O' ..IAII:U' DIY PIiIODS 12 WilKS flOODING WET ,ElIOD$

'ALl UDueUON O' LOW All AND WATII UM'U...TUIIS 4 WEEKS AVnAGI A" flM'- A.D lOW, nAIU nAGI II""UII TO O·C

Figure 4. Seaso ns, their cha racteristics and duration in the Colville Riv­ er delta, Alaska.

o , o Ul '

C"'j"l:j" ...... e-c ...... "':::J"t.Oc:.o"":!"t'--e-mMC'l autumn discharge is low. The end of autumn might be con­ tO~ ~c.O~~t--=~t--=U'5~o:i~et5U'5 sidered to occur at th e time th e first ice begin s to form in a delta's water bodies.

, Permafrost, Active Layer and Ice Wedges Ul E Permafrost , with its ass ociated features, is one of th e most importa nt environmenta l factors in arctic deltas. It is present in conti nuous form along all of the arcti c coast except in west­ C'lO ...... lCC'1""'l.Cl .....-l Om ~ O .....-lt.O o C"tjlCMC'lM ....-lOO OC'l C"J ""' CO ...... ~ ern Russia , Scandinavia, and th e southern part of the Bering ....-l l.Q - t.O "'d'....-l C\l ...... Sea. In even th e most arctic of deltas, water bodies Oakes, river channels and the sea) that are deep enough (two or more meters) have unfrozen zones (taliks) beneath th em. It is a condition th at has been used to adva ntage in th e acqui-

CRO SS SECTION OF DURING BREAKUP FLOODING METERS HWL Rj------f<- 4

o

4

Figure 5. River channel ice during prebreakup flooding.

J ournal of Coasta l Research, Vol. 14, No. 3, 1998 724 Walker

thin because of the flat of the surface and the fre­ quency of wind that drifts snow away from flat surfaces. Ear­ 5 ly in the melt season, flats and bars become snow free and x--- Date of Breakup serve as source for silt and sand transport up onto ~ 4 a.> .....J the adjacent tundra surface (WALKER, 1967). Thus, sand a.> .Sd 3 dunes are quite common in down-drift locations within arctic a.> > o deltas (Figure 8, insert B). ~ 2

If) ~ 1 and Lakes ~ o Arctic deltas, as well as other arctic environments, are L.....L..~---L...JL...... L--.L..-L----'--L...... L.-....L-L---L.-..JL...... L...... L..-...L--'--.L.-.I...... L..-L---I.-L...... L.-....L.....L...... L...-.L...... L.-....L..-L---I.-L.....L.....L...... J 19 23 27 311 5 9 13 17 21 25 characterized by an abundance of ponds and lakes (Figure 8, May June insert C). These ponds and lakes display highly varied sizes, Figure 6. Stage and breakup for selected years in the Colville River shapes, depths and methods of formation. They are present delta. in a variety of deltaic environments including old river chan­ nels (e.g., oxbow lakes), terrace-flank depressions, thaw de­ pressions, inter- and intra- depressions, swales in sition of sand and gravel (because of its unfrozen state) for and deposits, low-centered polygons and the troughs construction materials (WALKER, 1994b). between polygons (DAWSON, 1975; WALKER, 1983a). One of the forms found in permafrost zones is the ice wedge Many of the features of these ponds and lakes are a reflec­ (Figure 7, insert A). Ice wedges vary in size and spacing de­ tion of their relationship to permafrost. By far, the most com­ pending on the type of material in which they form as well mon type of water body in those deltas with ice-wedge poly­ as the prevailing temperature conditions. In some delta ma­ gons is that present in the low center of polygons and the terials, especially peat and fine-grained sediments, ice wedg­ troughs between adjacent polygons (Figure 8, insert D). Most es occupy as much as one-third of the upper three or four of these ponds are shallow and freeze to the bottom during meters of the tundra. Because of their growth characteristics winter. Other types of ponds that owe their existence to per­ they have unique surface expressions in the form of ice-wedge mafrost are those occupying blowouts in a dune or depres­ polygons. In many arctic deltas, such as the Colville, Lena, sions between dune bands. These ponds, which are often Yana and Indigirka, they dominate most of the non-aqueous perched well above , although shallow, retain their surface (Figure 7, insert B). integrity only because permafrost prevents percolation Ice wedges are important not only in connection with their through the coarse grained dune materials (WALKER and surface expression but also because of their role in riverbank HARRIS, 1976). . River flow, especially during flooding, often under­ Thawing of permafrost is a major factor in altering deltaic cuts banks forming what the Russians call a termoerozionaja lakes. Frozen banks are subject to thaw as well as wave ac­ niza (thermoerosional niche) that, under the right conditions, tion, and depths increase as a result of subsidence ac­ can extend as much as 10 m under the permafrost-consoli­ companying thawing of the permafrost beneath lakes. When dated (Figure 7, insert C). Such undercutting can lead lakes expand into zones of ice-wedge polygons they may cause to block collapse that often occurs along ice wedges (Figure inversions of reliefby thawing the ice-wedges over which they 7, insert D) (WALKER and ARNBORG, 1966). In peat banks it move. is usually the ice wedges themselves that erode (melt) first, Among the most drastic changes occurring in arctic deltas isolating the solid portions of the polygons (Figure 8, insert are those associated with lake tapping (WALKER, 1978). Lake A). tapping is the result of the erosion of banks that separate the In permafrost dominated environments, summer temper­ lake from the river channel. During initial draining, a plunge atures are sufficient to thaw the surface materials to varying pool develops at the lake entrance producing, as in the case depths. This freeze/thaw zone, known as the "active layer," of the Colville , some of the deepest parts of the tends to be thickest in coarse-grained sediments such as sand river channel. After tapping, the lake level fluctuates with dunes and thinnest under sphagnum-type vegetation. In the river stage, and the lake becomes a settling basin for the most arctic of deltas, active layer thickness varies from a few that enters it. The lake deltas that begin to centimeters to two to three meters. Because the active layer form near the lake entrance eventually grow to such an ex­ is relatively thin, it contributes little ground water to tent that they virtually fill the former lake basin. Those lakes channels and helps maintain the watery nature of most sur­ that were sufficiently deep to have a talik beneath them may faces. become so shallow that permafrost forms. Such conditions of­ ten lead to the formation of pingos and ice-wedge polygons Mudflats, Sand Bars and Sand Dunes (MACKAY, 1973). Mudflats and sand bars are common in arctic deltas. Be­ Flooding and Breakup cause of the extreme seasonality of river discharge, most flats and bars are submerged for only a short period of time. How­ Arctic delta formation, maintenance and modification de­ ever, in contrast, because of climate, they usually are covered pend to a large extent on the character of river flow and river­ with snow for most of the year. Normally this snow cover is ice breakup. Although the volume of discharge reaching del-

Journal of Coastal Research, Vol. 14, No.3, 1998 Arctic Deltas 725

c

Figure 7. Forms and processes in Arctic delt as: (A) Longitudinal view of exposed ice wedge. (B ) Ice-wedge polygons. (C) ThermoerosionaI niche cut beneath a peat ban k. Note th e ice wedge along which th e block colla psed two days after th e photograph was tak en . (D) Large colla psed blocks. Note the ice wedges in th e collapsed blocks and in th e vertical bank.

tas is highly varied, even reaching more than 600 krn" per In so far as geomorphic activity in a rctic deltas is con­ yea r in th e case of the Lena River, the timing of maximum cerned , th e few weeks of pre-breakup flooding, breakup ­ flooding and breakup is quite similar near the mouths of riv­ ing and post-breakup flooding are dominant (Figure 4). Dur­ ers draining into the Arctic Ocean. The month of maximum ing thi s peri od, the ice, as it moves down river , is involv ed in discharge is usu ally June-in some cases, as for the Olenek , erosion, (Figu re 9, insert A), and deposi­ Kahtanga, Kolyma and Colville, more than 40% of the a nnua l tion (Figure 9, inserts B and C). Depending on the nature of flow occur s in June (Table 1). Breakup itselfin deltas usu ally breakup, river ice (most of it two or more m thick) can phys­ occurs in late Mayor early June. ically erode riverbanks and scour the bars and flats over

J ournal of Coasta l Research, Vol. 14, No.3, 1998 726 Walker

B

..'

.,. ..,,':".. , '". ., .

Figure 8. Form s and processes in Arcti c delt as:(A) Ice-wedge polygons showing blocks re ma ini ng aft er th e ice-wedges have th awed . (B) Sa nd dunes typica l of arc tic delt as. Ph oto of th e Len a River delt a by Felik s Are . (C) Lak e types. Note the two large lak es which still retain some of th eir ice cover and th e nu merous low-centered ice-wedge polygons from which th e ice has melted. (D) overlying an ice wedge betw een polygons.

which it is moved. It also frequently becomes stranded and, holes in the ice and th en progresses seaward under the ice as it melts, deposits th e material (sand, gravel, vegetal de­ as a freshwater wedge (Figure 10). The downward flow of the bri s) it had picked up on its movement downstream (Figu re floodwater establishes whirlpools and, upon touching the bot­ 9, insert D) . tom , results in what Reimnitz has call ed "strudel scour" During pre-breakup and breakup flooding , floodwater (RE1MN1TZet al., 1974 ). As the floodwater moves over th e sea moves over adjacent sand bars and mudflats as well as th e ice it deposits sediment on the surface of th e ice. Although bottom-fast ice of the distributaries and the nearshore ocean som e of this sediment fall s to the ocean floor in place as the areas . As it moves out over sea ice it eventually reaches float­ ice melts, some of it is lost to the delta as th e ice moves out ing ice and flows down through pressure-ridge cracks or other to sea or along the coas t.

J ournal of Coasta l Research, Vol. 14, No. 3, 1998 Arctic Deltas 727

Figure 9. Forms and processes in Arctic deltas: (A) River ice and breakup flooding. Note severa l blocks of ice with sedime nt on top indicating th at they wer e originally bott om-fast , Th ese blocks can be up to two meter s in thickness. (B) Sediment deposited on top of snow on a mudfl at during flooding. (C) Sedim ent deposited on sea ice eight kilom eter s out from th e shore of th e Colville River delta. (0) Vegetal mat erial and rocks trans porte d from upriver and deposit ed on the tundra surface of th e delta.

The most dramatic morphologic process occurring during that form them are short, for example the rivers breakup flooding is the development of the thermoerosional draining the and Richardson Mountains of niche which leads to the block collapse described above (Fig­ . However, some , like those formed by the ure 7, insert D). Lena and Mackenzie Rivers, are among the largest in the world . Arctic deltas also come in shapes th at range from the ARCTIC DELTAS: EXAMPLES classical fan-shape of the Lena and Olenek deltas to nearly Deltas are a common landform along arctic coast lines. rectangular as exhibited by the Ob and Yenisey deltas. Most are small because in many locations the rivers and Because of the nature of the bordering seas (ocean cur-

J ournal of Coasta l Resear ch, Vol. 14, No. 3, 1998 728 Walk er

COLVILLE RIVER DELTA BREAKUP FLOODING -1973

Figure 10. Diagram illu strating the flow of floodwater over th e sea ice at the front of th e Colville River delt a.

rents, tides, ice cover), marine impacts, although different, Nanuk Delta are generally less important than is the case for many of the deltas in other parts of the world. Arctic deltas form in a As the distributaries of a delta migrate, they frequently tap number of different situations: some are found on the open lakes that become sm all basins into which floodwater and coast, others behind barrier islands and still others in broad sediment enter. Th e Colville delta has a number of such river valleys and (DUNLAP, 1990 ). Th e 10 arctic del­ lakes, all of which, when they begin to fill with sediment, tas discussed below have been selected to illustrate such vari­ develop deltas. One such lake delta is that form ing in Lake ables as age, size, shape, discharge, sediment load and sur­ Nanuk off the Nechelic channel of the Colville River. face forms. They include five from North America and five Lake Nanuk, before tapping, had an area of 2.52 km -, pos­ from Siberia. sessed depths of some 5 m, and had a level more than 3 m above the normal summer level of the adjacent river channel (ROSELLE and WALKER, 1996 ). Although the precise date Lake Nanuk was tapped is unknown, it probably occurred 1948 1955 1972 about 1940. The first aerial (low oblique) photos, which were taken in 1943, show that the lake flooded during breakup. By 1948, the date of the first vertical photographs of the area, a small delta had begun to form and was visibl e at low stage (Figure 11). Since that time, Nanuk delta continued to grow and, by 1992 , had separated the lake into two parts (Figure 11). A series of sediment samples obtained in 1983, by which time about one-half of the lak e had become sub-aerial , show that the sediment at the apex of the delta was 59% sand, whereas at the margins it was 93% silt and (ROSELLE, 1988 ). Although inorganic sediments transported onto the delta during breakup flooding predominate, much organic material and occasionally gravel and even large rocks are brought to it by river ice. Because the Nanuk delta is now exposed, it is subject to permafrost development. Frost cracks are already present and, as they grow, ice-wedge polygon s will form. Conditions also seem favorable for the potential growth of a pingo. The Figure 11. St age s in the form ation of th e Nanuk delta. The lake, which history of such lak e deltas, although geologically very had a water area of 2.52 km 2 at time of tapping, lost more than half of it short, display many of the characteristics of larger, longer­ by 1992. lasting deltas that are forming in the Arctic.

Journal of Coastal Research, Vol. 14, No. 3, 1998 Arctic Deltas 729

(Figure 13). Mackay wrote that at th e time "A large volume of debris probably swept sea ward to build a fan delta or a delta"(MACKAY, 1958). Just when the pre sent delta began to form is unknown. Some explorers (e.g., Viljalmur St efansson) have commented on th e fact th at the delta appeared smaller th an one would expect for a river the size of the Horton. In 1950, th e year aerial photographs of the area were made, the delta had an area of 30 km 2 (MAc KAY, 1981). However, by 1965, its area was only 25 km 2 (YORATH, et al., 1975). It was suggested that 1,,0 20 rapid down-cutting through the coastal bluffs had contribut­ kilometers ed large amounts of sediment to the sea that resulted in a rapid growth of the delta. Some time after the delta reached Figure 12. Th e Hort on River delt a. Map after Mackay (1981). its maximum size, destructive marine processes began to dominate over the constructive , and the del­ ta began to decrease in size. Delta Yukon River Delta One of the newest deltas to form on th e open sea coast is the Horton River delta (Figure 12). The Horton River, which Th e modern Yukon River delta (Figure 14) is th e most re­ today is about 570 km long, broke through a 100 to 150 m cent addition to an older and larger deltaic system. As in the high coastal bluffsometime prior to 1826, the year John Rich­ case on th e , th e course of the Yukon River ardson sailed in Franklin Bay (FRANKLIN, 1828). Th e river, has been periodically diverted. Such diversions, which appear which was about 100 km longer before breakthrough, was to be initiated by extremely high , have occurred at flowing at 6 to 7 m above th e level of Franklin Bay at the lea st four times in the Yukon syste m with the most recent time of breakthrough. It created a that was still in change in cour se occurring between 2500 and 1200 years ago evidence when Richardson's surveyor sketched it in 1826 (DUPRE, 1978). Since this last diversion , the Yukon has built

Figure 13. Mouth of th e Hort on River as drawn by E.N. Kend all on th e 1825-1 827 Fra nklin expedition. Print, courte sy of th e Rare Book Collection, Special Collections, Louisian a State Universi ty.

Journal of Coasta l Research, Vol. 14, No.3, 1998 730 Walker

lfGEND [. U l'\C on~ o lido t 'l'd ~\;" STAMUKHI\ SH 0 RE FA S T IC E I Hering Sea SEASO NAL PACK ICE ZONE floating fast ice I bottomfast ice 8:3 Ouo lernory VoI

A. WINTER

Figure 14. Yukon River delta. Figure 15. Zonation of ice in th e Yukon River delt a: A. Winter. B. Break ­ up illu strating sedime nt disper sion . After Dupre (1982). a 3000 km 2 delta out into Norton Sound, which is a shallow (less than 20 m deep) embayment of the Bering Sea. The Yukon River originates in , is 3185 km The Mackenzie River , with a length of 4240 km , is second long (the fifth longest in North America), drains 855 X 103 in length only to the Mississippi- in North km 2 of the Yukon Territory, Canada and Alaska, U.S .A., and America and the 12th longest in the world . The same rela­ has an an nual average discharge of 4457 m3s- 1 (Table 1). It tionships hold for its which has an area of 176 flows through a variety of formerly glaciated and tectonically X 104 km 2 (Table 1). It, like the three large basins in Russia, active areas (COLEMAN et al., 1986). The sediments delivered includes large areas that have continental climates, , to the delta are mainly fine-grained and are of a quantity grasslands and deserts. that equals 90% of all sediment entering the northeastern Bering Sea (D UPRE, 1982). Because Norton Sound is shallow, the deltaic sediments, which are transported to it over the ice as well as in sub -ice channels, are subject to much reworking by waves, coastal Mackenzie River Delta C? currents and ice. The Yukon delta illustrates well the impor­ tance of ice on sediment dispersion (Figure 15). The shorefast ice extends out to a zone of pressure ridges that form at a distance of 10 to 30 km from the delta front. The sub-aerial delta is lobate in form and similar to the Lena River delta in that it is advancing onto an open coast. It is fringed by wide (up to 1000 m) mudflats and mouth bars. In some places the delta is prograding by more than 30 m per year. The delta plain ".. . contains a complex assemblage of active and abandoned distributary channels and channel bars, natural levees, interdistributary and lakes" (D UPRE, 1982). There are two main distributaries that are approximately 1 to 1.5 km wide and 10-15 m deep, that makes them slightly wider and deeper than the two main distributaries in the Colville delta.

Mackenzie River Delta The Mackenzie River delta (Figure 16) is one of the most investigated deltas in the Arctic and has been the site of ex­ ploration and research since Alexander Mackenzie descended N the river to the ocean in 1789. Although, as MACKAY (1963) notes, Mackenzie's major contribution was the river's discov­ ~ ery , he nonetheless contributed such descriptions of the delta as : the river ". .. flows in a variety of narrow meandering 0 10 20 30 channels, amongst low islands, enlivened with no trees, but I II II I I a few dwarf willows" (MACKENZIE [1801] as quoted in MACK­ km AY, 1963). The most recent research (since the late 1960s ) ha s been directly or indirectly associated with hydrocarbon Figure 16. The Mack en zie River delta. research.

Journal of Coastal Research, Vol. 14, No. 3, 1998 Arct ic Deltas 731

1200 ~ Postglacial deltaic ~ sediments RICHARDSON 900 MOUNTAINS 1.>.11.'.>.'.1 Glaciomarine %J,;:

'" 600 Quaternary sed iments; Q:; CARIBOU high icecontent 1i) • E common 300 V~ Poo rly consolidated -=-- tertiarysediments o MACKENZIEDELTA I:·:':::',j Mesozoicshales ,.' & sandstones -3DO-t----,---r-----T'----,---.----...,..------,---,----t­ o 40 60 80 ,100 120 140 160 180 kilometers FIgur e i 7. Cross-section diagram of the Macke nzie delta nort h of Inuvik. After Fre nch and Heginbottom (1983).

The Mackenz ie River on average annua lly carries 281 km" delta they ". . . have little direct association with existing lak e of water to the delta thro ugh which it progresses to the sea basins . . ." and man y have been eroded by the sea (MACKAY, in cha nnels that are of varied gradients and lengths (ra nging 1963). from about 150 km to more tha n 270 km). The subae rial delta is an elonga te network of lake s and anastomosing channels The Colville River Delta (HEGINBOITOM an d TARNOCAI, 1983). The complicated na­ ture of the delta was emphasized by Mackay when, in 1963, The Colville River delta, wit h an area of only about 600 he wrote that ". . . its maze oflakes an d cha nne ls defies easy km-, is sma ll compared to man y arctic deltas; e.g., it has an description." Alth ough the bulk of th e Delta has been built area less th an 5% that of the Mackenzie delta which is the by the Mackenzie River , the western part also receives sedi­ Arctic 's second largest. Noneth eless, the Colville delta dis­ ment from other, shorter rive rs. plays most of the form s and processes foun d in the other arc­ The Mackenzie delta (FRENCH and HEGINBOITOM, 1983), tic deltas. with a subaerial area of 12,995 km", is second in size among The Colville River drainage basin, which is about 100 times arc tic deltas exceeded only by that of the Lena River. It is the size of its delta, covers 29% of the North Slope of Alaska. formed in a ". . . river-er oded, glacier-mo dified structural Unlike the larger drainage basins in the Arctic, that of the trough .. ." with sediment that reaches to depths of 90 m Colville is entirely confined to the zone of continuous per­ (Figure 17) (LEWIS, 1991). Lewis dist inguishes bet ween th e mafrost. The only non-perma frost locations it contains are southern part of the delta, which is tree covered an d domi­ those taliks that occur beneath th e deeper lakes and river nated by riverine processes, and the north ern part, which is cha nnels, i.e., those that do not freeze to the bottom during tree less an d influenced by tides and storm-surge flooding. winte r. Most forms and processes in the delta are affected by The northern part has numerous sma ll ponds, while in the per mafrost and include ice wedges, ice-wedge polygons upp er delta, large lakes dominate. Within th e delta, lak es (which are nearly ubiquitous), thermokarst lakes and ther­ occupy about 25% of the area and, as in the Colville delta, moerosiona l niches (WALKER an d AANBORG, 1966). serve as sinks for sediment that is mostly silt and fine sand The delta head s more than 40 km upstream from th e ocean (FERGUSON and , 1991). and has several distributaries that flow west and north west The delta has a low gradient that continues offshore in the from the main cha nnel (Figure 18). The act ual number of form of a subaqueous delta with an area of about 7000 km". distributaries in the delta varies with stage an d ti me. Be­ It is somewhat paradoxical th at, while deltaic is cause of nume rous bifurcations and rejoinings, there are cont inuing, the delt a front is eroding at a rate of about two more tha n 5200 routes that water entering at the head of th e meters per year. Although the tidal average is low (-34 em), delta can take before reaching the sea (WALKER, 1983b). storm surges and ris ing relative sea levels appear to be re­ The of the main channel is deep enough (up to 12 sponsible for the retreat. m) to remain open during winter, which allows sea water to Among th e many forms related to perm afrost presen t in penetrate upstream to a dist ance of 60 km. These dee p chan­ the delta, th e conica l-shaped pingo sta nds out . MACKAY nels do not free ze to the bottom so that during pre-breakup (1963) rep orts that th e area has more th an 1400 pingos. They flooding, river ice floats on top of the floodwate rs (Figure 5). vary in size, ranging in dia meter up to 600 m and in height In the Colville delta, the flooding period accompanying break ­ up to 45 m. They are present in the distal portion of the up is usually about three weeks long with breakup occurring modern delta an d in the Pleistocene deposits to th e east near the time of maximum stage (Figure 6). It is also during where the largest nu mber is foun d. There they occur in this period of flooding that the sa line water that has intruded and silts and generally in drained lakes. Within the modern into the cha nnels is flushed out and a fres hwater wedge is

Journal of Coasta l Research , Vol. 14, No. 3, 1998 732 Walker

13.6 44 9 H' A;

--MAIN CHANNELS --SECONDARY DISTRIBUTARIES --SUBSIDIARY CHANNELS

NUMBER TOTAL LENGTH KM 9 218.9 71 220.5 42 60.2 TOTAL 499.6 KM N Figure 19. Th e Lena River delt a: (1) Olenek cha nnel. (2) Erge-Muora ­ t Sisse.(3) Trofimov cha nnel. (4) Bykov channel. After Suslov (1951).

Figure 18. The Colville River delt a emphasizing its distributary system. water . The largest, known as Trotinorskaya, has been di­ verted strongly toward the east. The month of maximum flow is in June (Table 1); more than one-third of the annua l dis­ created in th e ocean in front of the delta. The tran sition from charge occurs during that month. The June amount is about sea water, with sa linities as high as 600 K at the bottom of 60 times that of April. the nearshore cha nnels, to fres hwater can take place within Most of the Lena delta is geomorphica lly active because of: a few hours. (a) the great quantity of sediment (mostly sa nd and silt) de­ livered to it; (b) erosion initiated by river water especially The Lena River Delta during flooding; (c) ice jams that aggravate flooding; and, (d) wind tha t transports much sa nd onto the upper surfaces. The Lena River delta (Figure 19), th e largest delta in the Thermoerosion and bank collapse (Figure 20) frequently oc­ Arctic and the third largest in the world, has an area of 3.2 cur as does the development of thermoka rst ponds an d lakes. X 104 km-, which has grown to a size that is about 1/78th Ice-wedge polygons are common, an d pingos (Figure 21) that that of its drainage basin. The Lena River is 4250 km long ran ge in height from 10 to 35 m an d in diameter up to 150 and has its origin in the Baikal Mountains more than 20° of m are numero us (SUSLOV, 1961). latitude to the south. Its head waters are very near those of During most of the yea r, when the water level is low, nu ­ the Yenisey River. In addition to the Baikal area the Lena merous sand bars are exposed and ". .. the general pattern River also drains part of the Siberian platform . The Lena of the channels becomes unrecognizable" (SUSLOV, 1961). The River is a good exa mple of those long arctic rivers that trans­ front of th e delta, which KOROTAYEV (1986) has classified as port the characteristics of th e temperate latitude of thei r or­ an open-ocean mouth type, has many channels with bars that igin to the coast, chara cter istics that are felt far out into the are modified regularly by waves, some of which reach heights sea. In addition, sediments transported to th e sea are partly of 2.5 m (COLEMAN et al., 1986). incorpo rated into th e sea ice (RACHOLD et al., 1997). The Lena delta origi na lly was estuarine in that its apex is The Yenisey and Ob River Deltas some 75 km inland from th e origi na l coastline (Figure 19). 3s 1 However, with the river's great discharge (16,650 m - ) an d In contrast to th e Lena and Olenek River deltas, the Yen­ sediment load (17.6 X 106 ta - 1) , the delta soon began to ad­ isey an d Ob deltas are located at the head of long and some­ vance into the open ocean, even surro unding outliers that what sinuous estuaries (rias, bays, gulfs, gubas) that exte nd now penetrate through it as isla nds. SUSLOV (1961) wrote inla nd from the Kara Sea (Figure 22). These two, joined by that ". . . there are more than a thousand islands in the delta, those of the Taz and Gyda nsk bays, are the world's longest most of which are small." One of the large islands, known as narrow bays ; the Ob is more tha n 800 km long (ZENKOVICH, Erge-Muo ra-Sisse, has an area of 6997 km", It is relatively 1988). These two deltas, although much smaller tha n the high, has many lak es and is generally un cut by channels (Fig­ Lena delta, are still the fourth (Yenisey) an d fifth (Ob) largest ure 19). in Siberia, with areas of 4500 km 2 and 3200 km ", respective­ In contrast, the rest of the delta possesses more than 800 ly. channels. Of these, 10 are large and carry the bulk of the Both the Yenisey and Ob Rivers are long and, like the

J ourn al of Coastal Research, Vol. 14, No.3, 1998 Arctic Deltas 733

Figure 20. Block collap se of stratified bank materials in the Lena River delta. Pho to by Feliks Are.

Lena, have th eir headwaters in th e mountains to th e south more continenta l and therefore drier portion, occupying 83% and flow across extensive lowland s and swam ps before en­ of the total area. tering th eir delt as. This tran sit across lowlands and Among arctic rivers, the discharge of the Yenisey at 19,600 resul ts in the depositi on of much sediment brought from th e m3 s- 1 is th e lar gest and that of the Ob at 13,500 m3 s- 1 is highland s before the water reaches the delt as. The drainage thi rd behind the Lena. Together , th e Ob and Yenisey carry basi ns are about th e same size; th e Yenisey has an area of 86.7% of all fres h water tha t enters the Kar a Sea . The river 2.59 X 106 krn-, th e Ob of2.55 X 106 km", which ranks them water that passes through the deltas of the Ob and Yenisey as sixth and eighth in th e world. The basin of the Yenisey is quite warm during summer.It also carries large loads of River is asym metrical with its right bank section, i.e. the flotsam from th e swamps thro ugh which it passes. Much de-

Figure 21. Pingo in drained lake in the Lena River delta. Photo by Felik s Are.

Journal of Coastal Research, Vol. 14, No. 3, 1998 734 Walk er

Figure 23. Maps of th e Indigirka and Kolyma deltas.

delays freezup. In combination, these two phenomena in­ Figure 22. Map s of the Ob and Yeni sey River delt as . crease the navigation season by nearly a month in these del­ tas (A"ITONOV, 1967). During peak floods on the lower reaches of th e Yenisey the river stage may exceed 20 m, which causes "... inundation, bris is left on the bars and islands of the deltas (SUSLOV, jamming, and the of large quantities of ice on the 1961 ). Although the average discharge for the year is less than banks and floodplains . . ." (ANTONOV, 1970). Because these deltas are at the heads of long gulfs , they are subject to surg­ 20,000 m-s" , the maximum for June during flood can es, some of which may be more than two meters in height. be quite high. For example, for the Yenisey, the maximum is l 154,000 m3s- , which contrasts with its minimum of 2080 The Indigirka and Kolyma River Deltas rn-s", only 1I75th as much. Winter flow through the deltas tends to be low and many channels freeze to the bottom. Al­ The Indigirka and Kolyma Rivers flow into the East Sibe­ though the major difference in discharge is between spring rian Sea (Figure 23) with their entire lengths confined to the flooding and winter sub-ice flow, even during the navigation zone of continuous permafrost (Figure 2). The se two rivers season (J uly- October) discharge varies from about 11,000 have created deltas that are different in size and shape. That m3s- 1 to more than 36,000 m3s- 1 (IVANOV and KOTREKHov, of the lndigirka at 5000 km 2 is larger than that of th e Kolyma 1971). at 3200 km-. Their origins are reflected in their size and Both the Yenisey and Ob deltas are elongate, almost rect­ shape. The Indigirka delta occupies a broad, shallow bay that angular, in shape, because of their formation in restricted formed during the rise in sea level and is generally fan­ environmental settings. Thus, they fit in Korotayev's cate­ shaped with a front that extends for 150 km across the coast­ gory of deltas that are infilling gulfs along with the Taz , Pur, line; whereas, the Kolyma delta was , for most of its history, Anabar, Khatanga and Kolyma (1986 ). They tend to develop confined to a long, narrow bay (Figure 23). In thi s sense it is a network of sinuous channels and as the ".. . inlet fills, form­ more like the Ob River delta than the Indigirka (Ko ROTAYEV, ing a consolidated , within which former deltaic is­ 1986). However, it ha s now reached the general coast and is can be distinguished only in air photos, the main dis­ growing seaward (MIKHAILOV, 1997). charge is transferred to the largest residual water body, as The discharges of th e Indigirka and Kolyma Rivers are arc­ ... is beginning to occur in the case of the Yenisey delta" tic in type in that nearly all flow is confined to the three (Ko ROTAYEV, 1986). These deltas have subaerial portions summer months (June, July, August). In the case of the In­ that are 180 km (Yenisey) and 110 km (Ob) long. However digirka, more than 80% of the flow occurs during those three the subaqueous portions extend for hundreds ofkm into their months. Both rivers have minimal flow during winter. For respective gulfs . the Kolyma , flow between November and April is only 3.5% As in oth er arctic deltas, the period of spring flood and of the annual amount and for the Indigirka it is only 1.5%. breakup is especially important. Breakup, according to IVA­ In both cases April is the month ofleast flow. The lowest flow NOV and KOMOV (1973 ), is somewhat unique because of the reached by the Indigirka in 1956 was 3.2 m3 s- l . The winter position of the delta at the head of a gulf. In the gulf area flow of the Kolyma is mainly the result of warm water fed to out in front of the delta, ice mostly melts in situ and the ice the from sub-permafrost springs. edge retreats gradually northward. Within the delta itself, Suspended load transport amounts are even more extreme. there is the combined influence of heat from river water, solar For the Indigirka, 92% of sediment discharge occurs during radiation and advecting air masses as in the gulf but with June, July and August with June, during breakup, having the added dynamic forces of flood water, wind and water-level the largest amount. At the head of the Kolyma delta the av­ oscillation. The se processes clear the river earlier than would erage annual sediment load is 8.2 X 106 ta - I (Table 1) , an otherwise be the case. Further, during autumn, warm water amount that has decreased in recent years because of the

J ournal of Coast al Resear ch, Vol. 14, No.3, 1998 Arctic Deltas 735 construction of a upstream. As early as 1959, Turanov War II, in recent years such activity was expanded. For ex­ noted that the suspended sediment load of the Indigirka was ample, in 1986 enough pre-fabricated buildings to house 9000 much larger in gm:" than that for the other Siberian Rivers people were shipped to the mouth of the Ob River (ARM­ (Table 1) and was responsible for the intensive shoaling of STRONG, 1991). large areas of the Siberian Sea (TURANOV, 1959). From the standpoint of , the most important and Both deltas have two main channels that diverge from near publicized activity is that associated with the nickel/copper their heads and, in both cases, split further downstream with mining operations at Norilsk (OSHERENKO and YOUNG, some rejoinings (Figure 23). In the case of the Indigirka the 1989). From this complex, which is considered to "occupy first two main channels are about the same length at 130 km. The place" in Russia with respect to pollution, waste is dumped Kolyma's distributaries are basically parallel for a long dis­ into tributaries of the Yenisey River from which it travels tance downstream and each is about 120 km long. into the delta (VIL'CHEK et al., 1996). Other arctic deltas are Flooding accompanying breakup causes high river stages. also affected by pollution from mineral operations. At the head of the Indigirka delta the stage rises on the av­ Among the major offenders is the industry, erage 4 to 5 m, whereas at the head of the Kolyma delta it which is quite extensive in arctic river basins and deltas. Ac­ is about 1 m more. These high levels last for only a few days cidental spills and pipeline leaks are common. VIL'CHEK, et and soon decline after breakup. Although tides are minimal, ale write that "In West Siberia there are virtually no rivers surges sometimes amount to 1.5 to 2 m in the lower delta in in the Ob and Pur basins that have escaped pollution the Indigirka and even in winter are recorded at 50 to 60 km ..."(1996). upstream (MIKHAILOV, 1997). In the Kolyma delta, surges Arctic hydrocarbon development is not limited to Siberia. can be larger (2.5 m at the mouth) and travel further up­ The Prudhoe Bay discoveries of 1968 led to one of the major stream (280 km) than for the Indigirka. North American producers of oil that is transported to south Both deltas possess oxbow lakes, thermokarst lakes, ice­ Alaska from the Arctic by pipeline, not by sea. Although it is wedge polygons and pingos that are found in drained lakes. many kilometers east of the Colville River delta, 1998 wit­ The active layer is thin (50 to 60 em) and in the upper parts nessed the first major activity in the delta itself. The activity of the deltas the vegetation includes dwarf willow and birch in the Mackenzie delta has been quite intensive and by 1994 trees. However, across the middle of the Kolyma delta, larch exploration had established 48 significant oil and gas fields and birch occur in sufficient numbers to have prompted the (DIXON et al., 1994). use of the name Krai Lesov (Edge of the ) as the name Arctic deltas serve well as locators for both subsistence and of a town (Figure 23). commerical fishing (Figure 24). In the case of Siberia all areas and their offshore basins from the Ob to the HUMAN IMPACT ON ARCTIC DELTAS AND THEIR Kolyma are important. More than 20 species of are ex­ FUTURE DEVELOPMENT ploited. One of the most important is the white fish, which use deltas as their primary feeding sites. They represent Although human adaptation to arctic conditions is not new, more than 60% of the catch in Yakutian river mouths, such directly impacting the environment is. Once navigation be­ as the Indigirka and Kolyma where numerous fish factories came a world-wide activity much effort was expended in find­ have been established. ing a way to utilize Arctic waters for commercial activities. Several developments have impacted the Siberian fisher­ After several centuries of trying the first transit of what be­ ies, including (a) the construction of river ; for example, came the Northern Sea Route (NSR) was made in 1878-9 by the dam of the Hydroelectric Station in the Ob A.E. Nordenskiold. His ship, the vega, was accompanied by River reduced the spawning grounds of the Siberian sturgeon the Lena as far as the Lena River delta. There the Lena left by 75%; (b) pollution in some rivers, such as the Ob and Yen­ the convoy and remained working in the delta for 50 years isey, has also diminished the size of spawning grounds; and, (BARR, 1991). By then, trade by ship in the Ob and Yenisey (c) overfishing, especially in deltaic waters. In the deltas of deltas had begun. Development of the NSR progressed to the the Indigirka and Kolyma Rivers for example "... winter net point that by the 1930s ice breakers were used as escorts. fishing is based on taking the immature component of the BARR (1991) wrote that "By the outbreak of World War II ... population" (GUNDRIZER et al., 1989). regular, reliable movement of freight along the entire length One of the earliest products shipped from Siberia via the of the Northern Sea Route had become a reality." No such NSR is timber harvested from the extensive forests that routes have been established across the arctic waters of stretch across Siberia. Igarka, a major city south of the Yen­ North America. isey delta, accounts for 14% of Russia's exports. Most of it is floated down the river to be loaded on ships for sea Exploitation transport (NORTH, 1991). During the several decades of this It was early known that the Arctic has a wealth of miner­ activity, many logs have broken loose from log booms or rafts als. Even as early as the middle of the 19th century some and floated down river on their own to become stranded along entrepreneurs were making plans for their exploitation in Si­ river banks and especially in the channels and on the sand­ beria by sea. However, it was not until the 1930s that the bars of the delta. They have accumulated in such quantities machinery and other equipment associated with the mineral that today their recovery has become a commercial operation industry became a major part of freight shipped to the area (ALEKSEYENKO and TITOVA, 1988). (YAZIKOVA, 1977). Although there was a lull because of World Deforestation has other effects that impact river systems

Journal of Coastal Research, Vol. 14, No.3, 1998 736 Walk er

Figure 24. Drying white fish in the Colville River delta.

and deltas, and it can change the thaw/freeze characteristics ern" development of the Arctic began, some areas have been of the , accelerate formation, and change the dis­ made unstable by human actions. These include areas such charge and sediment load of the streams draining the area. as tho se discussed above in connection with deforestation and Arctic landscapes are known for their fragility and that de­ oil spills. Another example is associated with vehicular traffic spite (or because of) the fact they develop under some of the that can damage the tundra surface aggravating permafrost most difficult environmental conditions on earth. Since "mod- thaw and gully formation (OSHRENKO and YOUNG, 1989). Today, in some areas, strict governmental regulations have helped reduce such adverse affects, although continues in other areas. An example of a new development that is "environmentally friendly" is the practice of trans­ porting equipment across the surface only during winter when the tundra is protected by a snow cover. Another is the use of sand and gravel from deposits from deep rivers, lakes and the sea. In the Colville River delta dredged materials from the talik beneath the thalweg of the river (Figure 25) were transported by polyethylene pipe to the location of a 1500 m-long runway (W ALKE R, 1994b). Dredge materials are also being used in the construction of and housing pads in Nuiqsut, the village established on the Colville River delta in 1973 (Figure 26).

Arctic Deltas and Their Future

Such procedures as discussed above, combined with an en­ hancement of international cooperation in arctic develop­ ment, bodes well for the future insofar as human actions are concerned. The increase in exploitation that is almost certain to occur because of the arctic's wealth, especially in connec­ tion with oil and gas, presumably will be done with environ­ mentally sound procedures. Some of the most important changes likely to occur in Arc­ tic deltas (as well as other Arctic coastal areas) are those that Figure 25. Th e dredge used by th e North Slope Borough for obtaining will accompany the atmospheric warming that is predicted to sa nd for runway construction. occur. Present-day estimates are that temperature increases

J ournal of Coastal Research , Vol. 14, No. 3, 1998 Arctic Deltas 737

Research, Coastal Studies Institute, and the North Slope Bor­ ough . Assistance in the preparation of this pap er was fur­ nished by Kurt Johnson, V. Mikhailov and Dimitri Mesyan­ zhinov. Cartography was by Mary Lee Eggart and Clifford Duplechein, photographic production was by Kerry Lyle, and manuscript typing was by Polly McKenzie. Feliks Are fur­ nished the photographs of th e Lena River delta. To all of these organizations and individuals I ext end my heartfelt thanks.

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