Ninth International Conference on Permafrost ... - IARC Research

Environmental Controls for the Coastal Processes on Yugorsky Peninsula,Kara Sea, RussiaIntroductionThe study area on Yugorsky Peninsula, coast of theKara Sea, is noted for active coastal processes (Kizyakovet al. 2006). Dynamics of bluff and thermocirque edgeswas monitored in 2001–2007, and landscape units weresubdivided using satellite image and field data. The paperpresents joint analysis of field and remote-sensing data fromtwo key sites: Pervaya Peschanaya and Shpindler. Someaspects of environmental controls for the coastal processesare discussed.Detailed knowledge of landscape components for remotearctic areas is relatively scarce (Virtanen et al. 2004).Therefore, a combination of remote sensing and fieldmethods was applied to determine response of specificlandscape units to coastal processes.Both key sites were used to work through methods of estimatingcoastal retreat rate/landscape unit correlation. To understandlandscape-coastal process links, a satellite image wasclassified, and retreat rates at the same plot were measured.Prior to the field study, main classes were subdivided ona satellite image Landsat 7 ETM+ with 15 m resolution inone panchromatic band. The most suitable combination ofmultispectral bands was used for accurate identification ofclasses as specific landscape units subdivided according to thelandscape classification of Melnikov (1983). Characteristicsof landscape units related to 25 identified classes were basedon field studies during the last 3 years (2005–2007). Theyincluded descriptions of landforms, vegetation, and activelayer depths within each landscape unit. At the coastal bluffand thermocirque edges, retreat was measured in 2001, 2005,2006, and 2007. Maximum retreat of each of landscape unitwas calculated for 2001–2005, 2005–2006, 2006–2007, andfor the entire observation period (2001–2007). Then theaverage annual was calculated by summarizing a maximumretreat for a given landscape during the entire period ofmeasurement divided by 6 years.MethodsSuperposition of the classified satellite image andtacheometric map of the coastal thermocirques at PervayaPeschanaya and Shpindler key sites shows the following.Landscape resistibility to the coastal processes depends onseveral environmental factors: slope inclination, moisture/drainage conditions, active layer depth, vegetation complex,and its coverage.Statistical analysis of the bluff-edge position againstlandscape units for both key sites provides some indirectretreat rate dependence on environmental controls.Landscape units subject to coastal processes are subdividedinto three groups according to their resistibility to coastalArtem KhomutovEarth Cryosphere Institute SB RAS, Tyumen, Russia135retreat: Irresistible, Medium irresistible, and Resistible. Thegroup of Medium irresistible landscape units is subdividedas a landscape complex, changing its resistibility due toclimate change.Maps for each key site are compiled, showing landscapeunits, combined into groups marked with different colorsdepending on their resistibility to coastal processes.Results and DiscussionAverage maximum retreat rates calculated according tothe described methodology vary between 1.7– 4.6 m/yr for 6years. Landscape units are subdivided into 3 groups accordingto the rate of measured coastal retreat. Irresistible landscapesare those with a maximum annual retreat rate exceeding 7 m/yr. Resistible landscapes are those with a retreat rate less than3 m/yr. In between are Medium irresistible landscape units.The average maximum retreat rate for a group of Irresistiblelandscape units is 9.2 m/yr, while the Resistible landscapegroup shows only 2.4 m/yr average retreat rate. The Mediumresistible group is characterized by an average retreat rate of5.5 m/yr (Table 1).Landscape components considered as retreat controls areshown in Table 1. They include drainage, slope inclination,surface microrelief, vegetation coverage, and dominatingvegetation. Analysis of Table 1 shows that Irresistiblelandscape units are characterized mainly by slightly poorerdrainage conditions compared to Resistible landscapes. As arule, they are located on steeper slopes, with notable formsof microrelief, such as spot-medallions and hummocks, withrather well-developed vegetation cover and dominatingshrubby and mossy complexes. At the same time, landscapeunits belonging to a Resistant category are generally betterdrained, level to gently sloping flat surfaces, often bare orpoorly vegetated, with graminoid vegetation dominating.Medium irresistible landscape units are characterized byvariable landscape features, some of which are closer tothe Irresistible type, such as slope inclination and coverage,and some in the middle position between Irresistible andResistible types.It should be noted that Medium irresistible are worsedrained compared with both extreme types, which meansthat the combination of even extreme landscape componentsmay cause partial compensation of their effect.To analyze the role of each retreat rate control, we assigneda numerical score to each of the subdivided environmentalfactors enumerated in Table 1, based on our experience.The higher role of the control in retreat rate is presumed,the higher score is assigned. For example, poor drainage(wet surface) is assigned score 3, well drained (dry surface)has score 1. Intermediate drainage is scored as 2.