When spring tide occurrence comes in next month of those each specific year, the impact of sea level change will be hugher than only by sea level rise and
impacted area will be expanding. Spring tide in next 10 years Jan-2022 will increasing sea level and can reach 1.27 m above zero. With this level of sea
surface, the land area that will be impacted will reach ±5,059 Ha with all of it landuse properties, infrastructure facilities road, and water channel. Spring tide
in next 15 years Jan-2027 will increasing sea level and can reach 1.40 m above zero. With this level of sea surface, the land area that will be impacted will reach
± 5,581 Ha, covering ± 429 km of road, and ± 306 km of water channel. The ilustration of inundated area in next 10, 15 and 20 years can be seen in figure
4.11
Figure 4.11. Projecting inundated area in next 10, 15 and 20 tears from now
In the end of RPJP Jan-2032 spring tide will impacted ± 6,041 Ha of land area with ± 465 km of road and ± 328 km of water channel passing those
impacted land area. At that spring tide, sea level will reach 1.53 m so that the area that less than or equal to 1.53 m will be inundated by seawater. The
properties that impacted by inundation in next 10, 15 and 20 year can be seen in table 4.7.
Table 4.7. Properties that affecting by sea level rises combine with spring tide in next 10, 15 and 20 years
LANDUSE TYPE INUNDATED
AREA IN SPRING TIDE
2022 Ha INUNDATED
AREA IN SPRING TIDE
2027 Ha INUNDATED
AREA IN SPRING TIDE
2031 Ha
Pond 72.976
75.395 78.145
Freshwater Pond 33.873
34.447 37.678
Shrub 4.219
4.219 4.219
Embankment 2412.283
2506.440 2545.451
Building 909.127
969.521 1022.798
Estuary forest 4.382
4.382 4.382
Planting Area 18.125
45.402 83.177
Settlement 1180.228
1421.042 1549.582
Marsh 17.313
21.381 23.174
Grassland 215.679
248.405 279.21
Irrigated Farming Area 162.153
204.884 274.806
Moor 29.463
45.644 139.325
ROAD TYPE INUNDATED BY
SPRING TIDE IN 2022 Ha
INUNDATED BY SPRING TIDE IN
2027 Ha INUNDATED BY
SPRING TIDE IN 2031 Ha
Bridge 372.875
372.875 372.875
Flying Bridge 109.393
109.393 109.393
Collector Road 0.000
0.000 0.000
Other Type of Road 4445.178
16721.724 23629.495
Local Road 347398.108
397571.141 424099.110
National Road 5954.630
7275.504 10080.393
Footpath 6634.104
6974.709 7028.548
V . C O N C L U S I O N S A N D R E C O M M E N D A T I O N
5.1. Conclusions
Based on results of data analysis on eustatic and isostatic sea level rise and its impact to coastal area of Semarang City that experiencing subsidence especially
in term of submergence area, there are some conclusions can be derived. Realistic tidal elevation data that has been derived using FVCOM was
generated by included six tidal harmonic constituents S
2
, M
2
, N
2
, K
1
, P
1
, and O
1
altogether and didn’t count the effect of sea level rise to generate tides. As the result of tidal data analyst, the type of tides in Semarang coastal water is mixed
mainly diurnal tide with highest peak tide value is 0.473 m. and lowest ebb tide value is -0.231 m.
Global sea level change shown the linear increasing year by year since 1880 to 2009. The first time when sea level was equal to land was occurred in 1982 and
had been passing this equality until unpredicted year. Regional sea level change in Indonesia’s area also shows the increasing by the time with increasing level 2.535.
cmyear. As the impact sea level rise, sea level in Semarang City coastal water also increasing local sea level where height of sea level until 2010 was reached
94.669 cm MSL value and after correcting process using regional sea level rise, isostatic MSL in 2010 was 52.070 cm.
Even subsidence is not the main object of the research, land subsidence level location where tide gauge located can be estimated by calculate the deviation
between MSL data from tide gauge that experiencing subsidence and isostatic sea level. The result of estimation shows subsidence rate in Tanjung Mas area
location where tide gauge located is 7.1 cmyear. As the impact of Sea level rise, submergence area that formed in 2011 was
1,043.527 Ha and predicted increase 4.4 times by spring tides. Seawater also covered ±149 km of road and ±67 km water channel, so that those facilities can
run it function normally. Future projection shows that in next ten years submergence area will reach ± 3,627 Ha while in next 15 years submergence area
will reach ± 4,364 Ha and in next 20 years submergence area will reach ± 4,641 Ha. When spring tides occur, the impact of sea level change will getting worst
because area with altitude up to 0.47 from submergence area will be inundated by seawater.
5.2. Recommendations
Study on sea level change and its effect to submergence area in Semarang City coastal area has formulated several points of recommendations to local and
national government, peoples in Semarang City, researcher and all readers such as follows:
1. Future study can be examining the model of sea level change using
different tools and method like ROMS Regional Ocean Modeling System, HYCOM HYbrid Coordinate Ocean Model, or POM Princeton
Ocean Model so that the result of FVCOM software that used in this research can be compared.
2. A deep survey and analysis of the latest condition about subsidence,
inundation data record, water transport from upland through river to complement the result of this study so that the impact of total flood can be
measured. Counting economic lost also can complement the result of this study.
3. Sea level change and subsidence that has been occur in Semarang and
threaten human life and welfare because the lost as the impact of this hazard will be so huge need serious, integrated and sustainable effort to
solve. Local government must be make strict rule to stop over water pumping one of the factors of land subsidence in Semarang City.
4. Build retaining materials, mangrove reforestation, and deepen the
embankment have to do to block sea water inundated land area and contain the water that has been covered land area
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APPENDICES
Appendix 1. 1. List of countries by CO
2
emissions from World Bank Countries with the highest CO
2
Emissions Country
CO2 Emissions per year 10
6
tons in 2006
Percentage of global total
Avg. emissions per Km
2
of its land Tons
China 6,103
21.5 636
United States 5.752
20.2 597
Russia 1,564
5.5 91
India 1,510
5.3 459
Japan 1,293
4.6 3421
Germany 805
2.8 2254
United Kingdom 568
2.0 2338
Canada 544
1.9 54
South Korea 475
1.7 4758
Italy 474
1.7 1573
2. Most polluted city by particulate matter from World Bank Particulate matter, gm
3
City 168
Cairo, Egypt 150
Delhi, India 128
Kolkata, India 125
Tianjin, China 123
Chongqing, China 109
Kanpur, India 109
Lucknow, India 104
Jakarta, Indonesia 101
Shenyang, China
