БЕРЕГА ОСТРОВА ИТУРУП: МОРФОЛОГИЯ, ДИНАМИКА, ПРОГНОЗ РАЗВИТИЯ

Abstract

Based on a field study (2019) of the Iturup Island coastal zone relief and interpretation of space images for the period 1980–2019, a morpholithogenetic coastal classification was developed and a map of the coast types was compiled. It was found that 85% of the coasts are eroding. But 80% of the coasts are stable and in fact have not undergone changes during the above mentioned period of time. Erosional coasts with poorly consolidated pyroclastic sediments retreat at an average speed of 2–2.5 m (up to 5 m) per year. Accumulative coasts in different parts of the island experience multidirectional movements: accumulation with an average speed of 1.5–2.5 m (up to 5 m) per year or retreat with an average speed of 1–2.7 m (up to 5.5 m) per year. In large bays, the directions of sediment movement were identified. All of the above mentioned observations are reflected on the coastal dynamics map. Also, the forecast of coastal development for the next 50 years was made. The most dynamic accumulative coasts, in general, will be advancing despite storm and tsunami erosion. The retreat of erosion coasts in poorly consolidated pyroclastics will depend on the height of cliff and the length of coastal collapse section, which determine the amount of material entering the coastal zone. Several sections of the coast (some of the undeveloped ones) were identified as favorable for the construction of berthing facilities.