SWorld – 17-28 June 2014 http://www.sworld.com.ua/index.php/ru/conference/the-content-of-conferences/archives-of-individual-conferences/june-2014 MODERN PROBLEMS AND WAYS OF THEIR SOLUTION IN SCIENCE, TRANSPORT, PRODUCTION AND EDUCATION‘ 2014

География - Геоморфология и биогеография

UDC 631.4:627.8+551.435.126+911.52 Starodubtsev V.M.

FLOW REGULATION IMPACT ON LAND COVER CHANGES IN RIVER DELTAS OF THE BLACK SEA BASIN

National University of Life and Environmental Sciences, Geroiv Oborony st., 15, Kiev

Abstract. Land cover changes in river deltas of the Black Sea basin as a result of

flow regulation and economic activity was considered. Space imagery (Landsat 2-5) and terrestrial investigations were used for this aim. Main accent was made on processes of new landscapes formation and land erosion on the sea coast in Ukraine and Romania.

Key words: river basins, runoff regulation, satellite imagery, environmental state, landscape formation, land erosion

Introduction. Deltas play an important economic and social role, especially in

connection with water use intensification for power, irrigation, water supply and other purposes. However, excessive use of water resources since the last century has led to a decrease in water and sediment inflow into the deltas and a change in their landscapes.

Monitoring of changes in the environmental state of deltas, long-term and seasonal dynamics of the processes of landscapes flooding or drying, we explore using Landsat satellite imagery and ground-based observations in the deltas of the Black Sea Basin, Central Asia and other regions [1-12].

We have proposed a generalized schematic classification of degradation processes in deltas, occurring under the impact of flow regulation and economic activity: 1. Depending on the climate zone such processes occur in deltas: a) Arid and sub-arid zone - desertification, salinization, deflation. b) Sub-humid zone - steppification of hydromorphic soils, poor soil salinity and alkalinity, in some cases - desertification. c) Humid zone - draining and degradation of wetlands and peat soils. 2. Depending on the geomorphology conditions: a) Continental (inland) deltas (Chu, Talas, Tarim, Heihe, etc.): fast and severe desertification and salinization, deflation.

b) Continental (inland) deltas, in which transfer of runoff takes place (Tejen, Murgab, etc.) - in the peripheral parts of them: flooding, waterlogging, salinization, desertification, deflation. c) Deltas on the coast of inland water bodies (sea, lake) - (Ili, Syrdarya, etc.): desiccation, desertification, salinization, deflation. d) Deltas in estuaries and narrow bays (Dnieper, Dniester, etc.): desiccation, overgrowing with hydrophytes and hygrophytes, meadow and riparian forests formation, weak salinity. d) Deltas in marine gulfs (Colorado, Euphrates, etc.): sea water intrusion into the delta, salinization, desertification, deflation. e) Deltas on the coast of the seas and oceans (Nile, Yellow, Mississippi, etc.): abrasion of a sea edge of the delta, an intrusion of sea water, draining, desertification, salinization. 3. Depending on land use in deltas: a) Rice cultivation: irrigated lands waterlogging and surrounding landscapes salinization (Syrdarya, Amudarya, Mekong, etc.). b) Intermittent irrigation of industrial, cereal crops and forage: drainage and desalination of irrigated lands and salinization and waterlogging of peripheral parts of deltas (Tejen, Murgab). c) Laying-in of fodder (reed and other macrophytic plants) in deltaic wetlands: drainage with water furrows, deltaic lakes dewatering and overgrow, partly – soil degradation and salinization (Ili, Chu, Dniester, Danube). d) Recreational, housing and industrial construction in deltas: drainage of landscapes, new lands inwash (especially at riverine levees), waste water discharge, river water “blooming”, etc (Dnieper, Danube, Don). 4. As a universal process in all types of deltas: subsidence of the earth's surface depending on the intensity of river flow regulation, a predominance of organic matter (peat) in soils, economic activity (especially in the deltas with megacities - Bangkok, Dhaka, Yangon, New Orleans, etc.). 5. Special processes will take place in deltas due to forthcoming sea level rise. Their intensity will depend on deltas topography.

Materials and methods. Space imagery Landsat 2-5 for the last 25 years was analyzed with ERDAS imagine program application. Change detection procedure was made to reveal areas with water surface overgrow and new landscapes formation or, opposite, land erosion on a seaside of the deltas. Some field routs were carried out in deltas with GPS use for land cover changes study. Results of previous investigations of deltaic landscapes were used as well.

Results and discussion. In the Black Sea basin the processes of landscape changes in the deltas of rivers flowing into the deep tide-free sea (Danube, Kizilirmak, Rioni), into the shallow sea (Don, Kuban), as well as into large estuaries (Dnieper, Dniester) are studied (Fig.1).

Fig.1. The Black Sea basin (River basins: 1 – Danube, 2 – Dniester, 3 –

Dnieper, 4 – Don, 5 – Kuban’, 6 – Rioni, 7 – Yesilirmak, 8 – Kizilirmak). In the Danube River delta decreased inflow of water and sediment, changed

seasonal and long-term hydrological regime as a result of flow regulation and economic activity in the basin. Therefore, in the delta of about 800-900 ha / year water surface is transformed into a land of lakes or wetlands due to siltation of reservoirs or economic activity. At the same time, the abrasion processes on the sea coast, as well as some renaturalisation of previously cultivated wetlands reduces the

Fig.2. Land cover change detection in the Danube delta.

area of terrestrial ecosystems at a speed of 400-500 ha / year. Consequently, the overall balance in the delta is formed in the direction of reducing the water surface and increasing the area of terrestrial, hygrophytic and hydrophytic ecosystems (Fig.2).

However, these changes are very dynamic in the years of different water content and manifest themselves differently in various parts of the delta that we study on seven key sections (Fig.3).

Fig.3. Key sections in the Danube delta. Key section 1 characterizes land cover changes in the area between the Kiliya and

Sulina river canals, section 2 – near the St. George canal, section 3 – near the Bystroe canal, section 4 – near the Ochakov canal, section 5 – agricultural lands, section 6 – area near the Rezim lake, section 7 – near the Sulina canal.

Fig.4. Key section 1.

1986 2011

Fig.5. Key section 2.

Fig.6. Key section 3.

Fig.7. Key section 4.

2011 1986

1986 2011

1986 2011

Fig.8. Key section 5.

Fig.9. Key section 6.

Fig.10. Key section 7.

1986 2011

1986 2011

1986 2011

Table 1. Land cover changes in key sections of the Danube delta. Type of surface 1986 2011 Changes, ha Key section 1. Deep water 19885,1 18422,1 -1463,0 Shallow water 599,4 1271,4 + 673,0 Reedstand and cattail with strips of sandbars and buildings

14167,0 14957,1 + 790,1

Total key-1 area 34651,6 34651,5 Key section 2. Deep water 10341,5 11454,9 +1113,4 Shallow water (plume) 6527,3 8428,5 +1901,2 Slightly overgrown water area 3150,7 226,2 -2924,5 Overgrown water area - 226,4 +226,4 Water area (total) 20019,5 20336,0 +316,5 Marsh land strongly watered 383,7 - -383,7 Marshes with reedstand and cattail

7589,0 5238,0 -2351,0

Dense reedstand and cattail with sands

2564,6 4982,9 +2418,3

Total area 30556,8 30556,9 Key section 3. Deep water 3276,9 3011,7 -265,2 Shallow water 596,2 701,1 +104,9 Overgrown water area 58,4 59,3 +0,9 Sandbars 49,4 78,9 +29,5 Marshes 1961,7 1306,2 -655,5 Dense reedstands and cattail with bushes (riverine levees)

1490,0 2275,4 +785,4

Total area 7432,6 7432,6 Key section 4 Deep water 8195,1 9771,5 +1576,4 Shallow water 4526,6 2778,8 -1747,8 Overgrown water area 1367,2 1070,6 -296,6 Marshes strongly watered 4066,8 2262,1 -1804,7 Marshes with reedstand, cattail and sandbars

8171,5 6839,4 -1332,1

Dense reedstands and cattail with trees and bushes (riverine levees)

1317,9 4922,7 +3604,8

Total area 27645.1 27645.1 Key section 5. Water area 5281,2 3815,8 -1465,4 Marshes 13817,3 4632,3 -9185,0 Waterlogged arable land 8080,8 14196,7 +6115,9 Wet fields (forage crops) 12712,9 21290,5 +8577,6 Dry fields (crops) 12164,1 8099,5 -4064,6 Built-up areas 1079,5 1100,5 +21,0 Total area 53135,8 53135,3 Key section 6. Water area 18521,2 16030,9 -2500,3 Water, strongly overgrown with 2203,5 2560,6 +357,1

macrophytes Marshes 6059,1 5679,8 -379,3 Reedstand and cattail with sand plots

13137,5 10707,6 -2429,9

Uplands and drying wetlands 4942,5 9884,5 +4942,0 Total area 44863,7 44863,4 Key section 7. Water of lakes 743,4 672,8 -70,6 Shallow waters (slightly overgrown)

415,5 - - 415,5

Water, overgrown with macrophytes

861,1 453,2 -407,9

Marshes and water 1403,5 964,9 -438,6 Reedstand and cattail 1715,7 2344,6 +628,9 Uplands at riverine levee 278,6 961,2 +682,6 Total area 5417,8 5396,5 (-27,3)

In deltas of the Kizilirmak River (coast of the Black Sea in Turkey, Fig.11) and

Rioni River (Georgia) similar processes occurs with much less intensity. Reservoirs construction in the Kizilirmak basin and straightening of the river channel caused drainage of the delta landscapes and land cover increase due to inland water area (Fig. 12). At the same time, processes of erosion at the seaside are very slight because of bank protection measures and stone deposits at a beach.

At the Rioni river delta processes of wetlands drainage related with civil and industrial construction. A significant part of the delta has been built up in a quarter-century in the town of Poti, and the coast is protected against erosion by the sea (Fig 13).

Fig. 11. Deltas of the Kizilirmak and Yesilirmak Rivers on the Black Sea

coast.

Fig. 12. Land cover changes in the Kizilirmak River delta.

Fig.13. Land cover changes in the Rioni River delta.

Table 2. Changes in land cover in the Rioni River delta for 1980 – 2009 (ha). Type of surface 1980 2009 Changes, ha Water area (river and lakes) 329.7 328.5 -1.2 Swamps 361.1 286.1 -70.0 Reeds 538.6 248.8 -289.8 Buildings (old) 605.9 539.8 -66.1 Buildings (new) - 448.8 +448.8 Meadow and forest 856.8 804.3 -52.5 Total area 2692.1 2656.4 (-35.7)

In the rivers Don and Kuban (Fig 14), which flow into the shallow Sea of Azov, deltas extension in the sea ceased due to the reduction of sediment runoff.

Fig. 14. Deltas of the Don and Kuban’ Rivers (MERIS, 2010).

However, water onset and negative setups phenomena caused by strong winds strongly affect here the transformation of the delta landscapes. Intensive industrial construction and aquaculture (the Don River, Fig.15, 16) and development of rice (the Kuban’ River, Fig. 17) significantly affect the reduction of wetlands area and floodplains.

Black Sea

Fig. 15. Land cover changes in the Don River delta for 1988 – 2011.

Fig. 16. Settlements expansion in the Don River delta (ASA-WSM-2011).

Fig. 17. Land cover changes in the Kuban’ river delta for 1986-2011.

The rivers flowing into long estuaries (Dnieper and Dniester) also ceased extension of their deltas in these estuaries (“limans”). Overgrowth of delta lakes and canals at a speed of 150-160 ha / year in the delta of the Dnieper and 30-40 ha / year in the Dniester delta take place there. In the waters of the deltas processes of "blooming" of water and the deterioration of their quality intensified (Fig.18-21).

Fig.18. Land cover changes in the Dnieper (Dnipro) delta. Left figure – zoning of the delta according to overgrowth intensity: 1 – very strong, 2 – strong, 3 – moderate, 4 – slight, 5 – water blooming, 6 – settlement extension. Central figure – points of terrestrial investigation with GPS application.

Right figure – an example of deltaic lakes overgrowth.

Fig. 19. Processes in the Dnieper (Dnipro) delta (left – summer houses building, center – water plants extension, right – water blooming).

Table 3. Land cover changes in deltas of the Dnieper and Dniester Rivers.

Type of surface Arae, ha Dnieper - delta Dniester - delta 13.07.1986 16.08.2010 15.07.1975 01.08.2011

Water area 11605,2 11567,2 16343,1 17166,1 Shellow water 2239,8 1563,8 1490,8 1063,4 Water, overgrown with floating plants, and fens 4709,7 1334,4 2410,2 1187,8

Settlements and anthropogenic-changed territories 1865,3 3180,7 - -

Overflow lands (“plavni”) with shrubs and forests 9052,9 9509,9 - -

Overflow lands (“plavni”) with reeds and cuttails 7910,1 10227,1 12579,9 11372,2

Swamps overgrown by reeds - - 4172,0 4045,9 Meadow waterlogged and upland, and settlements - - 8201,7 10362,3

Total area 37383,0 37383,0 45197,7 45197,7

Fig. 20. Land cover changes in the Dniester delta (left – 1975, center – 2011, right – an example of lakes overgrowth).

Fig. 21. Processes in the Dniester delta: left – lake drying-up, center – land development, right – soil salinization).

Investigation of the processes of landscape changes in deltas of the Black Sea is

now continuing with the use of Landsat-8 satellite images.

Conclusion. 1. Different deltas long-term study has enabled us to propose the classification of land cover changes in deltas according to climate, geomorphological features, land use and economic activity.

2. In the Black Sea basin different processes in land cover changes were revealed in deltas of the rivers flowing into the deep sea (Danube, Rioni and Kizilirmak), into shallow sea (Don and Kuban’) and into long estuaries (Dniper and Dniester).

3. In the Danube delta opposite processes (new landscapes formation and soil erosion) give balance of the increase of terrestrial ecosystems with the rate of 400-500 ha per year. In the Kizilirmak and Rioni deltas these processes are less intensive and a coastline protection measures – more effective. Main process in the Rioni delta is industrial and municipal construction.

4. In deltas on the coast of small and shallow Azov Sea their extension into the sea weakened due to sediments runoff reduce. Intensive industrial construction and aquaculture in the Don delta and rice production in the Kuban’ delta reduced of wetland area there.

5. Deltas of the rivers flowing into long estuaries have ceased their extension into these estuaries. Their overgrowth by hygrophytic and hydrophytic ecosystems takes place with the rate of 150-160 ha/year for the Dnieper and 30-40 ha/year – for Dniester delta.

References.

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