Study of Flood Disaster Risk Delta in Bojonegoro Regency

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which make it more difficult to determine [1].
The impact of flood risk is expected to increase due to population growth, economic development and climate change [2].Flood exposure and flood frequency are expected to increase, especially in low latitudes Asia and Africa [3].Foll owing a risk-based approach, flood risk assessment is widely applied at three scales: local scale [4], regional scale and global scale [5].This assessment aims to identify risk locations at different levels, namely: set as a basis for establishing mitigation and adaptation actions [6].
In most cases, catastrophic flooding is caused by excessive rainfall in a certain area over a relatively short period of time.Therefore, the level of risk is closely related to changes in the amount and intensity of rainfall in the future [7].In this study there are 3 stages of analysis starting from the analysis of hazard, vulnerability and risk delta.The method used in the analysis is the latest method, especially in terms of spatial modeling.This spatial modeling is carried out in the TIN and Raster databases so that it can accurately determine the magnitude and direction of the model.The initial stage in this research is in flood hazard analysis, using the hydrodynamic model method which is analyzed using a spatial analysis TIN database then in vulnerability analysis this research also uses cellular automata analysis in determining and predicting future vulnerability conditions.
This cellular automata analysis will also be supported by several logistic regression analyzes, neural networks and simweights to increase validation in the process of determining transition models in the analysis of determining future susceptibility conditions.The advantage of this research is in making future predictions with spatial analysis, both projected flood conditions and future vulnerability conditions projections to formulate risk deltas, namely the overlay results of current risks and future risks that are spatially projected.

Results and Discussion
Based on the analysis of land use change, it is known that in 2012 the area of the built-up area was 25,117 ha where the area was only 10.9% of the total land use area of Bojonegoro Regency as a whole in 2012.For more details, see the following table and map image.

Image 2
Kediri Regency Land Use Map 2020 Based on the results of the analysis of the driving factor analysis by means of a change analysis of land use in Bojonegoro Regency in 2012 to 2020, it was found that the transition from plantation land use to forest land use was the largest land use transition where plantation land use turned into forest land use of 70,106.73Ha. .Meanwhile, the smallest land use transition is the land use transition from settlements to pasture use, which is 0.02 Ha.From the simulation results, there are three scenarios in regional development, namely a trend scenario, a target scenario without constraints, and a target scenario with a trend.For more details, see the following image.
Proximity to Facilities Proximity to Activity Center Proximity to Existing Settlement Proximity to District Road Proximity to Provincial Road Proximity to National Road Image 3 Euclidean Distance Driving Factors From the simulation results, there are three scenarios in regional development, namely a trend scenario, a target scenario without constraints, and a target scenario with a trend.The following are the results of the land use simulation in 2023, 2028, 2033, 2038.The data can be seen in the following table.

Land
Use Prediction in 2025 Land Use Prediction in 2035 Land Use Prediction in 2030 Land Use Prediction in 2040 Image 4 Land Use Prediction in 2025-2040 From the simulation results table above, it can be seen that the area of mixed settlements in 2023 increased rapidly from 2020.The increase from the original area of 27,258.17Ha to 43,432.44Ha.This indicates that the settlement simulation results in a period of 5 years from 2020 to 2025 will increase to an area of 16,174.27hectares.Then the area of mixed settlements in 2030 will increase rapidly from 2020.The addition of the original area of 27,258.17hectares to52,168,51Ha.This indicates that the settlement simulation results in a period of 10 years from 2020 to 2030 will increase by 24,910.34hectares.The largest reduced land in the 2030 simulation is forest land, where the forest area has decreased from 9,361.71Ha in 2025, from an area of 60,106.89Ha in 2025 to 50,745.18Ha in 2030.In 2035, the largest land use change from 2020 based on the above simulation is the change in forest land use, namely a forest decline of 17,082.13Ha, followed by a decrease or conversion of agricultural land, which is 7250.32Ha.Meanwhile, in 2035 for settlements there was an addition of 30,695.84Ha from 2020.Based on the simulation results, settlements experienced a fairly large increase, which was 39,992.14Ha.Of course this also has an impact on the reduction of forest land and agricultural land, each of which is reduced by 50,081.57Ha for forest land and 46,186.03for irrigated agriculture from 2020 to 2040.The results of the simulation of land use in 2023, 2028, 2033, 2038, namely that the area of mixed settlements in 2023 is growing rapidly from 2020.The increase from the original area of 27,258.17Ha to 43,432.44Ha.This indicates that the settlement simulation results in a period of 5 years from 2020 to 2025 will increase to an area of 16,174.27hectares.Then the area of mixed settlements in 2030 will increase rapidly from 2020.The increase from the original area of 27,258.17hectares to 52,168.51hectares.This indicates that the settlement simulation results in a period of 10 years from 2020 to 2030 will increase by 24,910.34hectares.The largest reduced land in the 2030 simulation is forest land, where the forest area has decreased from 9,361.71 hectares in 2025, from 60,106 hectares in 2025, Flood-prone locations in Bojonegoro Regency according to the RTRW of East Java Province are in Kasiman District, Padangan, Kalitidu, Bojonegoro.Some areas of Bojonegoro Regency which are located in the Bengawan Solo watershed are flood-prone areas.Meanwhile, flood-prone areas caused by the Bengawan Solo watershed are along the river where the downstream the higher the flood intensity.The areas that have the potential for flooding are the Districts of Padangan, Kalitidu, Malo, Trucuk, Bojonegoro, Kapas, Sumberrejo, Kanor, Baureno.Spatial : Wahana Komunikasi dan Informasi Geografi |9 Results of Identification of Vulnerability Factors for Floods in Bojonegoro Regency in 2020.For more details, please see the following table and diagram.

Image 5
Bojonegoro Regency Flood Prone Area Diagram Based on the results of the physical vulnerability assessment of Land Use with indicators of Mixed Settlements, Irrigated Rice Fields, Rainfed Rice Fields, Plantations, Green Open Space, Fields, Grasslands, Forests, Shrubs, Rivers, Other Waters.all indicators use the reclassify method in Arcgis.In the scoring map, the weighting of each indicator is based on the results of the AHP analysis.For more details can be seen in the following table.

Image 6
Map of Bojonegoro Regency Flood Vulnerability in 2020 Based on the results of the scoring analysis of the physical vulnerability map of land use with indicators of Mixed Settlements, Irrigated Rice Fields, Rainfed Rice Fields, Plantations, Green Open Space, Fields, Grasslands, Forests, Scrub, Rivers, Other Waters, it was found that in the research area, physical vulnerability of land use fall into the category of high vulnerability, medium vulnerability and low vulnerability.Based on the results of the analysis of flood risk zones in Bojonegoro Regency, it is known that there is an area of 165.48 Ha or 4.34% in the High Risk category, 637.37 Ha or 16.73% in the Medium Risk category and 3,007.3Ha or 78 ,93% fall into the Low Risk category.Delta () flood disaster risk in Bojonegoro Regency sees the difference in changes from the flood risk in Bojonegoro Regency from 2020-2040.The purpose of this analysis is to find out whether the current and future changing trends in use can minimize the risk of flooding in Bojonegoro Regency or even increase the risk of Bojonegoro Regency.If there is an increase, it can be used as a reference for the local government in managing future development.The following is the change or delta of the flood risk zone of Bojonegoro Regency from 2020 to 2040 seen every 5 years.

Table 1
Land Use of Bojonegoro Regency in 2012 Source: Indonesia Landscape Bojonegoro Regency 2019 DOI: http://dx.doi.org/10.26555/bioedukatikaemail: bioedukatika@uad.ac.idImage 1 Land Use Map for 2012 In addition, it is also known that the development of residential land looks quite large, this can be seen from the 2012 area which was only 25,116.90Ha, increasing in 2020 by 27,258.17Ha.Land use in Bojonegoro Regency until 2020 is dominated by Irrigation Rice land use, which is 99,477.03Ha or 42.95% of the total land area.For more details can be seen in the following table and map image.

Table 2
Land Use of Bojonegoro Regency in 2020

Table 5
Flood Vulnerability Area of Bojonegoro Regency in 2020

Table 6
Area of the Bojonegoro Regency Flood Risk Zone

Table 7
Percentage of Flood Risk Zoning in Bojonegoro Regency