Coastal Vulnerability Assessment in Semarang City, Indonesia Based on Sea Level Rise and Land Subsidence Scenarios I. M. Radjawane, D. Hartadi and W. R. Lusano Oceanography Research Division Fac. of Earth Sciences and Technology Institut Teknologi Bandung,Indonesia Presented at the LOICZ OSC 2011, Coastal @ Oseanografi Systems, ITB Global Change and Suistainability Yantai, China, 12-15 September 2011
INTRODUCTION Coastal resources will be effected by a number of consequences of climate change, including: Higher sea levels Higher sea temperatures Changes in precipitation patterns and coastal runoff Changed oceanic conditions Changes in storm tracks, frequencies, and intensities
BLUE COUNTRY Located in the tropics between two continents (Asia & Australia) and between two oceans (Pacific & Indian Oceans) The place connecting the Pacific and the Indian Oceans in the lower latitudes Coastline length : 95.181 km (DKP, 2009) Country area : 1,919,440 km 2 Number of Islands : 17.508 High biodiversity of marine life
70% of Indonesian population lived in Java Island High development industry and infrastructures Low land coastal city area Indundation/Flooding problems
GENERAL CONDITION Semarang is the capital city of the Central Java province Semarang Area : 373.7 km 2 Population (2007) : 1.454.594 people, grow rate 1.41%/yr Population Density : 3.892 people/km 2 with denser population in the northern part
Semarang City, Central Java, INDONESIA heavy rainfall sea level rise erosion housing hotels/tourism restaurants fishermen trees brackishwater pond flooded area comercial areas Office buildings urban buildings tidal flood lost mangroves erosion land subsidence Salt water intrusion
Coastal Area of Semarang Housing Area Brackish water Sea wall
Population density within of a 10m Low Elevation Coastal Zone 41.610.000 peoples l ives in area below 10m (IIED, 2007) Semarang After :CIESIN, Univ. Columbia, 2007
GENERAL CONDITION Semarang consisted of two major landscapes, namely coastal plain area (1%) and lowland (33%) in the north and center and hilly area in the south. The northern part, is relatively flat with topographical slopes ranging between 0 and 2 0, and altitude between 0 and 3.5 m, where the city centre, seaport, airport and railway stations are located and more industrial and business area. The northern part of Semarang is composed by very young alluvium with high compressibility (Abidin et al., 2010) Mariculture and fisheries areas Semarang is a prone vulnerable area.
After Mercy Corps
FLOODING IN SEMARANG Stasion Airport Main Road Source : Various
INUNDATION MAP IN SEMARANG GPS TRACKING 23-24 OCTOBER 2009 Radjawane et al, 2009
LAND SUBSIDENCE IN SEMARANG 1. Natural Consolidation Process Young Alluvium Soil 2. Increases in the population and urban development in the area - increase land subsidence through excessive groundwater extraction, groundwater level rate lowering in period of 1980 and 1996 is about 1.2 to 2.2 m/year [Marsudi, 2001]. - Increase load of building and infrastructure
Land Subsidence Rate in Semarang GPS PS InSAR Courtesy of Geological Agency Bandung, after [Murdahardono et al., 2009; Kuehn et al., 2009]. After Abidin et al., 2010
Land Subsidence Impact in Semarang Courtesy to Abidin, H, Z et al., 2010
Semarang Shoreline Changing The shoreline of Semarang progresses relatively quick toward the sea, about 2 km in 2.5 centuries or about 8 m/year. Van Bemmelen, 1949; Marfai et.al. 2008 Courtesy to ACCRN, Mercy Corps, 2009
Digital Elevation Model of Semarang in the year 2000
Elevation Zone of Semarang City
SEA LEVEL RISE IN SEMARANG SLR 2002-2007 : 2.11mm/year Data collected from Ministry of Public Work After Lusano, 2010
Land Subsidence Map using in DEM Linear rate of land subsidence: 3.93cm/year Data collected from Ministry of Public Work After Lusano, 2010
Semarang inundation Area affected by Tides and Storm (Rob) Simulation of Tides+ Mitag+Hagibis Storm in Nov 2007 Hanifah, 2010 Annual Average of Inundated Height : 50cm
Projection 2025 SLR Scenarios SLR+LS Industrial Inundated Area (ha) SLR 97.60 681.3 Housing inundated Area (ha) SLR+LS 289.98 2016.87 SLR+LS+ Storm 319.97 2271.40 SLR+LS+Storm
Inundation Projection During HAT (Highest Astronomical Tide) Tidal Prediction 2010-2030 Occur every 18.6 years
Worst Scenario Sea Level Rise+Land Subsidence+Storm+Highest Tide Industrial Inundated Area : 321.97 Ha Housing Inundated Area : 2271.402 Ha
Parameters of Physical Coastal Vulnerability Index No Parameter Unit Description (a) Coastal slope % Linked to the susceptibility of a coast to inundation by flooding and to the rapidity of shoreline retreat or advance (b) Tide range meter Contributes to coastal inundation hazards (c) Wave height meter Linked to coastal inundation hazards (d) Sea-level rise mm/ years Correspond to how the global (eustatic) sea-level rise has affected a section of shoreline (e) Coastal geomorphology - Indicates the relative erodibility of a section of shoreline (f) Shoreline erosion/ accretion m/ years Indicates how fast a section of shoreline has been eroding or accreting CVI a* b* c* d* e* f /6 Adopted from Thieler and Hammar-Klose, USGS, 2000
Physical Coastal Vulnerability Map Semarang 2009-2050
COASTAL TYPE OF SEMARANG AREA After Marfai and King, 2007
Socio Economic Vulnerability Index After Szlafsztein, 2005
Socio Economic Vulnerability Map
Total Coastal Vulnerability Index
Total Coastal Vulnerabilty Index in Semarang City Hartadi, 2009
Government Strategies Mangrove reforestation and develop coastal bank Polder system construction Soft and Hard engineering construction - Sea wall construction along 2.4 Km - Improvement of road construction along the coast Action Plan based on Disaster Mitigation Study
DISCUSSIONS Local sea level rise and average land subsidence rate in Semarang are 2.11 mm/year and 3.93/year respectively. The annual height of storm/rob is 50 cm and the highest astronomical tide is 55cm. Land subsidence is significant component and combine with the sea level rise accelerated the coverage of inundation in Semarang coastal area. Coastal vulnerability map show high vulnerabilty region in dense population in northern part of Semarang because of geological and physical aspect, high dense population area and high development region. We need an integrated and multi discipline framework of action plan programs to cope the climate change problems.
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