Dynamics and Vulnerability of Delta Systems - loicz

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Shanghai, Dhaka, Lagos, New Orleans) makes them particularly vulnerable to storm surges and sea-level rise (see Table 2.1). Table 2.1: Population in 2000, and projected population growth to 2015 for thirty-one major deltas, both in developing and developed countries. (A. de Sherbinin calculations based on the following data sources: CIESIN et al. 2005a, 2005b, 2005c, and Kettner (unpublished delta delineations from SRTM DEM data). 16
CS3: Subsidence of the Po River Delta Albert Kettner Deltas are almost always prone to subsidence and the Po delta is no exception. Tectonics, sediment loading and sediment compaction are the main components driving natural subsidence rates for the Po Delta, which is only partly compensated by post-glacial rebound (Carminati & Martinelli 2002). The net natural subsidence rate for the Po Delta is estimated to be ~ 2-4mm/y (Simeoni et al. 2007). However, observed subsidence rates have been significantly higher since the 1950s. Anthropogenic factors like groundwater extraction accelerated as the area became more populated, but natural gas mining was central to increasing subsidence rates to 40-60 mm/y on average in the late 1950s, early 1960s (Fig. CS3.1a). Gas extraction in the Po Delta stopped at the end of the 1970s, which almost instantly decreased the subsidence rate to 10-20mm/yr (Fig. CS3.1b). It took till the 1990s to slow subsidence to its natural rate (Bondesan et al. 1995). Fig. CS3.1: Decreasing subsidence rates (A-C) of the Po Delta. A) Subsidence rates during active mining of methane rich water (after Caputo et al. 1970), B) Recovered subsidence rates when most mining activity stopped (after Bondesan & Simeoni 1983), and C) Simulated natural subsidence rates (after Simeoni et al. 2007). Over the same time, the demand for sediment for building material increased with the rapidly growing population. Between 1958 and 1981, 90-95 x 10 6 m 3 of sediment was mined in the lower course of the river (Simeoni et al. 2007). In addition there was significant sediment trapping in the upper drainage basin by dams and reservoirs. Elevated subsidence rates, decreasing sediment supply due to dam and reservoir interception, and sediment mining (Fig. CS3.2) caused major delta erosion after the 1950s. Fig. CS3.2: Sediment load decreased by a factor 2.9 in less than 60 years (after Syvitski & Kettner 2007). 17
Page 1: LAND-OCEAN INTERACTIONS IN THE COAS
Page 4 and 5: Published in Germany, 2009 by: GKSS
Page 7 and 8: Executive Summary Deltas form where
Page 9 and 10: Prolog Deltas all over the world ar
Page 11 and 12: 1 Introduction Deltas are the landf
Page 13 and 14: asin by switching and/or inundation
Page 15 and 16: The Indus River in Pakistan is one
Page 17: Fig. CS2: The evolution of the dist
Page 21 and 22: CS4: Rapid Caspian sea level change
Page 23 and 24: Deltas are probably as susceptible
Page 25 and 26: climatic characteristics resulting
Page 27 and 28: A 70% decrease in the Danube’s se
Page 29 and 30: Fig. 3.2: Villagers are building a
Page 31 and 32: consequences of changing water regi
Page 33 and 34: Ibanez et al. 1996, Day et al. 2007
Page 35 and 36: 3.4 The Importance of Extreme Event
Page 37 and 38: economically sustained based on an
Page 39 and 40: • Beyond scale, do small deltas f
Page 41 and 42: CS 10: Figure based on unpublished
Page 43 and 44: depth of flooding for 10yr, 20yr, 5
Page 45 and 46: chemical gradients and other non-li
Page 47 and 48: Indus delta or the Nile delta. Glob
Page 49 and 50: 6 References Alvarado, M. (2005): C
Page 51 and 52: Elvira, B. (1995): Conservation sta
Page 53 and 54: Osborne, P.L. (2000): Tropical ecos
Page 55 and 56: Global Planetary Change (39): 111-1

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