To protect peoples from worse inundation in future, local government of Semarang City was built concrete wall protection so that seawater can not
inundated land area. The protection also built along the river in coastal area to anticipating unstreamlined flow of the water from hilly part to the ocean.
Peoples realize that they are in harmful condition by inundation so that they preserve mangrove that starting growing as their natural protection.
4.3.3. Coastal Inundation at Spring Tide 2012
The effect of sea level change is not stop when it flooded an area permanently in term of sea level rise, but there some effect that causing by daily change.
Tides, as a factor of daily change, can exacerbate the impact to human living. Life quality become worst because when spring tide occur, flooded area
expanding. Some areas which not cover by water permanently will experiencing flooding and potentially converting into submergence area in the future. Based
on the amount of sea level rise in previous year and height of sea level on spring tide event in projected year, the inundated area can be predicted.
SL at spring tide in projected year = Real MSL at previous year + spring tide level
SL at spring tide 2012 = 0.546 m + 0.474 m
= 1.02 m Sea level at spring tide 2012 reached 1.02 m, it means seawater level is higher
1.02 meter than land. With assumption there is no reduction from recent retaining materials, DEM is delineated using 2008 topographic survey’s data as
the basic data time when retaining properties is not built yet, the land area with height less than 1.02 m will experiencing inundation. As the effect of sea level
rise and spring tide combination, flooding area expanding 4,597.249 Ha or almost 4.5 times than submergence area in 2011. The significant increasing of
flooded area is occur in settlement almost 117 times than it area in submergence condition, building almost 105 times than it area in submergence condition,
and grassland almost 33 times than it area in submergence condition. There is also occurring infinity increase of inundated area on some landuse properties, i.e.
shrub, irrigated farming area, and grassland, because there are no properties like that which being part of submergence area in 2011.
Road as the main transportation infrastructure is impacted by inundation. In 2011, more than 149 km of road was permanently covered by water and
predicted will inundated almost 2.2 times in spring tide 2012. Water channel as one of the natural hydrological control can’t play it function normally by this
phenomenon because some of it covered permanently by seawater. Around 66.9 km of river was permanently converted and will be inundated to ± 257.6 km by
spring tide 2012. The complete information about recent properties of submergence area in 2011 and predicted impacted inundated properties in spring
tide 2012 can be seen in Table 4.5. Table 4.5. Properties that affecting by sea level rises and spring tide
LANDUSE TYPE PERMANENTLY
COVERED IN 2011 Ha
INUNDATED BY SPRING TIDE IN
2012 Ha
Pond 22.939
70.991 Freshwater Pond
3.156 26.726
Shrub 0.000
4.046 Embankment
950.866 2246.048
Building 25.433
857.763 Estuary forest
4.382 4.382
Planting Area 6.001
12.735 Settlement
8.750 1018.501
Marsh 16.556
11.780 Grassland
0.000 195.109
Irrigated Farming Area 0.000
132.641 Moor
5.444 16.527
ROAD TYPE PERMANENTLY
COVERED IN 2011 m
INUNDATED BY SPRING TIDE IN
2012 m
Bridge 42.0950
372.875 Flying Bridge
97.2930 109.393
Collector Road 0.0000
0.000 Other Type of Road
24450.7700 4271.079
Local Road 111881.0900
301413.116 National Road
5973.6520 5370.778
Footpath 6994.8470
6398.546
