Capacity Assessment Spatialization to Disaster Risk Reduction in Semarang Coastal Area

Global warming be the one of threats to human civilization that has to be main considerations in environmental management. In addition, global warming is one of key driven factor of tidal flooding that affect many aspects in coastal area society. This study proposes to model capacity preparedness index of Semarang Metropolitan Coastal Area. The analysis divided by two substances, physical capacity and economy capacity. The examination and modelling of capacity preparedness level consider public health facilities availability, road network accessibility, and economy activity. The research uses quantitative methods and maximized the utilization of secondary data to capacity assessment. The findings show that capacity preparedness index of urban area is higher than its peri-urban. In total, Semarang Metropolitan Coastal Area have low-capacity preparedness level. There are only two sub-district which has high level capacity, Semarang Tengah and Semarang Utara. Otherwhile, there are three medium level capacity sub-districts and four low level capacity sub-districts. Those findings show that geospatial analysis can help people and government on how to understanding their capacity in dealing with disaster which cannot be predicted precisely.


Introduction
Global warming has been serious issue and problem to human civilization nowadays and has to be considerations in environment management [1][2][3].IPCC (Intergovernmental Panel Climate Change) estimates that earth average temperature will be increasing by 1,5 ˚C in 2030-2050 [4].One of threats because of global warming is sea average level rise [5] which has effect on demography system in coastal area [6].Sea level rise phenomena forces community to migrate from their houses in coastal area to area that further from shoreline (inland area).Sea level that higher than land area make sea water can inundating in land area, it is called tidal flood disaster [7,8].Tidal flood disaster cause destructive impact on human life.Flood in coastal area can cause damage on building, infrastructures and facilities, houses, asset and property, costs in industrial and commerce, and also disrupting the transportation traffic [9].Uncontrolled population growth, urbanization that don't well-prepared, climate change, and also expansion of human settlement in the flood-prone area be recognized as key drivers for the frequency and severity of flooding at the present and the future [10].Those facts indicate that society needs a solid solution to reduce rate of loss and damage due to tidal flood disaster in coastal area, specifically in Semarang Metropolitan Coastal Area.
The people is priority in disaster risk reduction planning.Policymakers need to observe and create policies that people's wealth-oriented.In disaster risk reduction context, policymakers and people itself 1264 (2023) 012021 IOP Publishing doi:10.1088/1755-1315/1264/1/012021 2 need to strengthen their capacity dealing with disaster.Government and public institutions have a crucial role in order to reduce the damage and losses to natural disaster [11] People need to adapt and overcome for the increasing disaster risk and have to prepare for disaster that could come anytime [10,12].It is so important to assess vulnerability and people exposure [13] and also people capacity resilience for disaster [10,14].Meanwhile, many people and communities, especially on developing country don't have or lack of appropriate resource to adapt for disaster due to climate change, as well as tidal flooding [15] Capacity conseptualized as metaphor to physical science, as theory, capacity, or strategy.United Nations International Strategy fo Disaster Risk Reduction (UNISDR) define capacity as capability of a system or community that vulnerable to disaster to withstand and recover from disaster impact [16].Meanwhile, [17] explains that capacity of the community can be examined by the communication aspect, desire to learn , and adaptation.
Previous study that attempt to assessing capacity preparedness [18] which use household aspect to his research variables.The variable what they use are sex and age of household head, household size, income, access to credit, educational level, flood experience, evacuation plan, community organization, etc.Also, he uses estimation technique of dependent and independent variables.The variable that yhey use are complex and comprehensive.The findings show that the status of household in viewing the flood impacts affect to people preparedness actions and socio-demographic characteristic.The output show preparedness correlation in general without explain the distribution on study location.
Other research [10] explain social and collective capital can be the driver factor to flood preparedness and reliance to community.Survey questionnaire instrument are utilized in this research.They use simple random and snowball sampling technique to collect data in the study location.It is the same with [13,18,19] and other researches about capacity preparedness and vulnerability aspects, as long we know they only considering to social and economy aspects.
This research aim to model capacity preparedness assessment based on Semarang Metropolitan Coastal Area.The study location have faced many disaster impact problems.Due to reduce lossess and damages to people, we need to analyze how strong the people and infrastructure have in facing tidal flood disaster.Lack of research done in Semarang Metropolitan Coastal area which discuss and examine capacity level based on spatial analysis.It might be the novelties on this research.

Research Location
Semarang Metropolitan Coastal Area consist of three regencies, there are Kendal Regency, Semarang City, and Demak Regency.Specially for Kendal and Demak, there is one sub-district each that be research study, there are Kaliwungu Sub-District (Kendal) and Sayung Sub-District (Demak).Meanwhile, study location on Semarang City is consisted seven Sub-District, there are Tugu, Semarang Barat, Semarang Utara, Semarang Tengah, Semarang Timur, Gayamsari, and Genuk.
Semarang Metropolitan might be the one coastal area in Indonesia which has high vulnerability to natural disaster, particularly tidal flooding.High frequency and intensity of tidal flooding are because land subsidence factor due to excessive groundwater extraction, highly dense population on coastal area, shifting landuses, and also geography factor that located on shoreline of Pantai Utara Jawa.Those findings consider the researchers to conduct research about existing capacity preparedness level in terms of physical and economy capacity to strengthen the study location capacity in facing tidal flooding.Following Figure 1 which shows study location area coverage.Semarang Metropolitan Coastal Area be selected because of its frequency of tidal flood disaster that damage and cause lot of losses almost every year, especially on rain season [20,21].In addition, study area coverage of this research consider publication from Badan Penanggulangan Bencana Daerah (BPBD) from each regency (Figure 2).Semarang Metropolitan coastal area has 237.55 km 2 area.Sayung be the the largest sub-district (47.78 km 2 ), meanwhile Semarang Tengah is the smallest one (5.17km 2 ).In study location, urban area concentrated on Semarang City, particularly in Semarang Tengah, Semarang Barat, Semarang Utara, and Semarang Timur.Other sub-district has function as hinterland of its urban area.For the detail, Table

Research Data
Capacity assessment divided by two substances, there are physical capacity and economy capacity.The variable considers Sendai Framework for Disaster Risk Reduction 2015-2030 (SFDRR) to be framework for assessing capacity of Semarang Metropolitan Coastal Area.There are four principles in SFDRR document in order to reduce disaster risk: (1) understanding disaster risk, (2) strengthening disaster risk governance to manage disaster risk, (3) investing in disaster risk reduction for resilience, an also (4) enhancing disaster preparedness for effective response.
Priority 3 and 4 used as variable to examine capacity level preparedness of Semarang City Coastal Area to tidal flood disaster.From the selected principles will be detailed in existence of road network, health facility, and also economy activity to show study location economic resilience.Therefore, the researchers maximized the utilization of road network data, availability of health facility, and night-time image data (to show economy activity in Semarang Metroplitan Coastal Area) [22,23].

Research Method
This research uses quantitative method to analize capacity preparedness level of Semarang Metropolitan Coastal Area due to tidal flood disaster to minimalize loss and damage because of it.The researchers use secondary data to fulfill data requirements.In addition, secondary data will be used to validate the output using online platform, such as Google StreetView. Figure 3 below explain how the analysis of the research.Figure 3 above explains that the objective of this research is to assess capacity preparedness of Semarang Metropolitan Coastal Area based on spatial analysis.It means, the data requirements need to be in spatial format.That consideration linked with the principle or priority in SFDRR document to reduce the disaster risk based on people capacity to recover and defend theirself from the disaster.In this context, there are road network, public facility distribution, and night-time data.Those data is needed to analize physical capacity and economy capacity of Semarang Metropolitan Coastal Area.In the end, physical and economy capacity carried out to fuzzy overlay to produce total capacity preparedness of study location

Physical/Infrastructure Capacity
Physical capacity or infrastructure resilience describe the capacity of built infrastructure that have to continue functioning during the disaster.In this context, the infrastructure might include, hospital or local public health center, road, and also bridges [17].Furthermore, road network and medical rescue point have a significant role during the disaster in order to evacuate the victim.More compact or dense the road network, it will ease the evacuation procces..It is the same thing to medical resque point, when it is more distribute it will ease the process of evacuation of victim.The victim will faster to get helped and the possibility of lifeloss will be decreased [22] The researcher acquires road data network from Open Street Map webpage and the public health center point distribution retrieved from InaRisk rest services.Then, the road network and medical health center point data processed by kernel density tools from ArcMap 10.2.Value of the kernel density output need to be in index value (0-1) so we use fuzzy membership method to convert the value.Each indexed value of health public point and road network is needed to overlay to generate infrastructure resilience or physical capacity.

Economy Capacity
Assessing the economy capacity level of Semarang Metropolitan Coastal Area considering nighttime brightness to check the wealth-level of people.Brightness level ff nighttime of some urban area representing how strong its economy activity [22].The brighter nighttime light, it indicates the economy activity and GDP are stronger, especially on urban area.
The researchers acquire nighttime brightness data from Google Earth Engine datasets.VIIRS (Visible Infrared Imaging Radiometer Suite) collects global low-light imaging data that have significant improvement and also generated monthly and annually to observe nighttime [24].Image from VIIRS need to clipped to study location boundary.The imagery sometimes don't has right coordinate system and same pixel size, therefore it needed to reproject and convert the pixel size.Then, value from raw data from VIIRS satellite is needed to convert to index value (same as physical capacity analysis).The process produce indexed nighttime data to show Semarang Metropolitan Coastal Area economic strength in order to recover from tidal flooding showed by Figure 4

Physical Capacity Model
It has mentioned before that physical capacity assessment consist of medical health data and road network density.Physical capacity or infrastructure resilience is very significant and crucial in mitigation and recovery process due to disaster, in this context is tidal flooding.Proper road network and availability of medical health center can reduce loss and damage on people or building [17,25].Following Figure 5   According Figure 5 above, we can see that the public facilities and road network concentrated on urban areas, such as Semarang Tengah, Semarang Barat, Semarang Timur, Semarang Utara, and Gayamsari.It is normal because population in urban area is more dense and higher rather than periurban area [26].More people that live in some area, it will more facility and services provided to support the people activity.
In the other hand, peri-urban area as well as Kaliwungu, Tugu, and Genuk have less public facilities and road network density compared with urban areas.It indicates that urban area has higher capacity than non-urban area because the distribution of health facility and accessibility don't distributed well and equally, particulary in Tugu Sub-District which is lack of public health facilities and accessibility.It makes Tugu Sub-District more vulnerable due to flooding disaster.In addition, its location that located in the shore line make Tugu Sub-District more hazardous to people lived in there.
High-rates of tidal flooding hazard creates high vulnerable community.The community must adapt and overcome the disaster condition that might interrupting their activity or even causes more fatality.In this context, people should be has more proper road access and public health facilities to reduce the fatality level.
Each of health public facilities and road network density output analysis be the requirement of infrastructure capacity in total.The following Figure 6 below show the infrastructure capacity in total of Semarang Metropolitan Coastal Area.Lack of physical capacity in non-urban areas means high vulnerability rate to disaster.Areas that don't well-reachable to health facilities and road network will be in trouble if disaster appear unpredictable.Number of public health and segment of road that limited, it means less alternative we have when one of those infrastructure having damaged or disrupted.It means infrastructure system are interdependent to other aspect of infrastructure itself or even to socio-economic aspect [27][28][29].Those considerations need local government's attention to enhance quality and quantity of infrastructure and also its distribution, specially on non-urban/peri-urban area such as Tugu and Kaliwungu Sub-District.
Public facility need to be provided with good accessibility.When some area or city has a high number and dense of public facilities, but it is not kept pace with road access development it will be a pointless thing.In addition, public health and road network accessibility are several crucial infrastructure that must be provided in the region or urban area [29].It is extremely important to develop resilient infrastructure system eventhough the functions under threats of disaster hazard.Developing urban infrastructure resilience can help stabilize infrastructure functions, reduce threats to public and health safety, and also restore critical infrastructure system functions [27]

Economy Capacity Model
This research utilized nighttime data to see how productive is Semarang Metropolitan Coastal Area in economical aspect.When the light is brighter, it indicates the economy rotation running highly intense and significant [22].We utilized VIIRS nighttime data to analyze economy capacity of the location study.VIIRS nighttime data proceed by warp and reprojected to fulfill the terms of pixel size (all of the raster data in this research have 30 x 30 m pixel size).According Figure 7 above, we can see that the urban area has brighter nighttime light rather than its peri-urban.Intensity of nighttime light can be produced from people'shouse, commercial and services area, and also road network of the area.Typically, urban area has more frequent economy activity, traffic intensity, and lot of commercial area.Then, from the indexed value of nighttime data, we can conclude that urban area have higher economy capacity instead of non-urban area.
Urban area that have highest intensity nighttime light specially Semarang Tengah is the center of urban area in Semarang Metropolitan Coastal Area.There are extensive commercial and service facilities and also be one of densely populated sub-district in study location.In other words, its people might have high income and lot of resources rather than people from other area.Wealthy people have a higher economy capacity because of the resources that they have.Wealth enables people or community to recover from losses an damages faster because of the access to insurance, entitlement programs, and social safety nets [30].Otherwise, people with low socioeconomic status have lower capacity and higher vulnerability [31].

Total Capacity Model
Capacity total of Semarang Metropolitan Coastal Area consist of physical capacity and economy activity that has been explained before.Capacity preparedness total output come from fuzzy overlaying process with the supporting software ArcMap 10.2. Figure 8 below shows map output of capacity preparedness of study location.

Figure 8. Semarang Metropolitan Coastal Area Capacity Total Index
Higher the region or urban capacity then the potency of losses and damages because of tidal flooding will also decrease.Based on Figure 8 above, we can conclude that urban area have higher level on capacity preparedness rather than non-urban area.Refer on findings before, high level of urban capacity because of the availability of road access and public health facilities which concentrated on urban area.In addition, urban area have the high contrast of nighttime view (indicator of economy activity) than non-urban area.Following Table 3 below show the capacity classification distribution for each sub-district in Semarang Metropolitan Coastal Area.According Table 3 above, we can conclude that the classification domination of study location capacity is on low level.But in the other hand, there are two sub-district which have high level capacity due to tidal flooding as well as Semarang Utara and Semarang Tengah.Otherwise Tugu, Genuk, Sayung, and Kaliwungu have low level capacity preparedness.Gaps between high and low level capacity area depends on distribution of public facilities that don't well-distributed.In addition, sub-district which have low level on capacity preparedness lack of road access and economy activity either.Therefore, those findings support previous study [17,22,25] which explain there is correlation between public health facilities density, accessibility of road network, and economy activity contribute to region resilience.
Capacity preparedness is one of possible things to do to reduce disaster risk of coastal area, particularly Semarang Metropolitan Coastal Area.Upgrading the capacity preparedness not only considering social aspect, but also the infrastructure system [9] due to tidal flooding risk management through enhancing and strengthening the infrastructure system condition.

Conclusion
The research successfully modeled Semarang Metropolitan Coastal Area capacity preparedness due to tidal flooding disaster based on spatial analysis.Sendai Framework for Disaster Risk Reduction 2015-2039 (SFDRR) be the framework of variable and data determination.Capacity assessment on this research divided by two substances, there are physical capacity and economy capacity.Physical capacity accommodate public health facility distribution and road network accessibility variable to embody infrastructure resilience.Economy capacity consider the economy activity to examine the prosperity level of location study society.
The findings show that urban area have higher level of capacity preaparedness rather than nonurban area.It is because of the facilities and also society condition on urban area more well-prepared by its local government and people [32].Those findings clearly show that infrastructure and society resilience are important thing in order to reduce disaster risk.People, community, and government should coordinate and communicate each other to embody region resilience.
The methods and approaches in this research can be maximized to examine and create policies for the society.Government and the other stakeholders can make the decision based on priority needed to enhance capacity preparedness with spatial distribution consideration.It will optimized time management to determine priority area to get helped and handed.
The research method have some limitations.The variables are too limited and less variety.Varies variables and indicator can produce capacity model which more accurate and detailed.The data that 12 used in this research fully-acquired from secondary sources and it need to be clarified and recheck for the validations.The models should be validated in real time and on it's real place to examine how accurate the model is.

Figure 4 .
Figure 4. VIIRS Nighttime Data (Google Earth Engine's datasets, 2023) below shows road network and health facilities density map of Semarang Metropolitan Coastal Area.

Figure 7 .
Figure 7. Raw Data of VIIRS Nighttime and Its Indexed Value (Analysis, 2023)

Table 1 .
1 below shows the details of each sub-district in this research.1264 (2023) 012021 Study Area Coverage 4

Table 2
below explains the selected SFDRR 2015-2030 priorities and data used.

Table 2 .
Research Data

Table 3 .
Capacity Distribution and In Total