Spatial Analysis Of Potential Floods In Belawan Watershed Using Geographic Information Systems (SIG)

Introduction

Belawan watershed, located in the region of 3 ° 15 '49.83' 'to 3 ° 50' 38.89 '' north latitude and Meridian 98 ° 29 '58.56' 'to 98 ° 43' 21 , 76 '' East Longitude, is a flood-prone area that experiences almost annual flooding. This phenomenon mainly occurs in December to February, when rainfall reaches its peak and causes the river to overflow due to its inability to accommodate large water discharge. The purpose of this study is to map the potential of floods in the Belawan watershed using a combination of hydrological and hydraulic analysis with geographic information system (SIG) technology.

Methodology

To map the potential of floods in the Belawan watershed, this study combines hydrological and hydraulic analysis with geographic information system (SIG) technology. The Nakayasu synthetic unit hydrograph method is used to calculate flood discharge, while Hec-Ras software is used to predict water level and flood inundation area. Secondary data used include rainfall data, debit data, and topographic data. Spatial analysis using ArcGIS software integrates Digital Elevation Model (DEM) data, infrastructure maps, and river maps in flood conditions predicted by HEC-RAS. This data allows the identification of flood-prone areas and estimated potential losses it caused.

Results

The results showed that the potential for flooding in the Belawan watershed was very significant. In the 25-year-old period, floods are estimated to reach a water level of 2 meters with an inundation area of 40.33 km². In the 50-year-old period, water level reached 3 meters with an area of 86.38 km² inundation, and in the 100-year-old period, the water level reached 5 meters with an inundation area of 148.43 km².

Losses Due to Floods

Losses due to floods in the Belawan watershed not only harm property, but also have a significant impact on the economy and welfare of the community. Estimation of losses based on the Bappenas Report Assessment of Damage to Jabodetabek 2007 indicates that the flood of 25-year repeat period has the potential to harm Rp. 10,556,879,257, a 50-year repeat period of Rp 1,117,876,476,188, and a 100-year repeat period of Rp 2,056,310,863,138.

Infrastructure Affected by Floods

Infrastructure affected by floods in the Belawan Das includes main roads such as Medan-Binjai Street, Gatot Subroto Street, Gaperta Ujung Street, Jalan Kelambir V-Jalan Pinang Baris, Sea Port, and railroad lines.

Conclusion

The results of this analysis show an urgency in the implementation of flood disaster mitigation strategies in Belawan Das. Increasing the capacity of river infrastructure, the construction of an early warning system, as well as community education and awareness programs on the dangers of flooding become important steps to minimize the negative impact of flooding in the region.

Recommendations

Based on the results of this study, the following recommendations are made:

• Increase River Infrastructure Capacity: The capacity of river infrastructure should be increased to accommodate large water discharge and prevent flooding.
• Construct Early Warning System: An early warning system should be constructed to alert the community of impending floods and allow them to take necessary precautions.
• Community Education and Awareness Programs: Community education and awareness programs should be implemented to educate the community on the dangers of flooding and the importance of flood disaster mitigation strategies.

Future Research Directions

Future research directions include:

• More Detailed Hydrological and Hydraulic Analysis: A more detailed hydrological and hydraulic analysis should be conducted to better understand the flood dynamics in the Belawan watershed.
• Integration with Other Flood Disaster Mitigation Strategies: The results of this study should be integrated with other flood disaster mitigation strategies to develop a comprehensive flood disaster mitigation plan for the Belawan watershed.

Limitations of the Study

The limitations of this study include:

• Limited Data Availability: The availability of data was limited, which may have affected the accuracy of the results.
• Simplification of Flood Dynamics: The flood dynamics in the Belawan watershed were simplified, which may not accurately represent the complex flood processes that occur in the region.

Conclusion

Q: What is the Belawan watershed and why is it prone to flooding?

A: The Belawan watershed is a region located in the area of 3 ° 15 '49.83' 'to 3 ° 50' 38.89 '' north latitude and Meridian 98 ° 29 '58.56' 'to 98 ° 43' 21 , 76 '' East Longitude. It is prone to flooding due to its inability to accommodate large water discharge, which occurs mainly in December to February when rainfall reaches its peak.

Q: What methods were used to map the potential of floods in the Belawan watershed?

A: The Nakayasu synthetic unit hydrograph method was used to calculate flood discharge, while Hec-Ras software was used to predict water level and flood inundation area. Spatial analysis using ArcGIS software integrated Digital Elevation Model (DEM) data, infrastructure maps, and river maps in flood conditions predicted by HEC-RAS.

Q: What are the estimated losses due to floods in the Belawan watershed?

A: The estimated losses due to floods in the Belawan watershed are significant. In the 25-year-old period, the flood has the potential to harm Rp. 10,556,879,257. In the 50-year-old period, the flood has the potential to harm Rp 1,117,876,476,188. In the 100-year-old period, the flood has the potential to harm Rp 2,056,310,863,138.

Q: What infrastructure is affected by floods in the Belawan Das?

A: The infrastructure affected by floods in the Belawan Das includes main roads such as Medan-Binjai Street, Gatot Subroto Street, Gaperta Ujung Street, Jalan Kelambir V-Jalan Pinang Baris, Sea Port, and railroad lines.

Q: What are the recommendations for flood disaster mitigation in the Belawan watershed?

A: The recommendations for flood disaster mitigation in the Belawan watershed include increasing the capacity of river infrastructure, constructing an early warning system, and implementing community education and awareness programs on the dangers of flooding.

Q: What are the future research directions for flood disaster mitigation in the Belawan watershed?

A: The future research directions for flood disaster mitigation in the Belawan watershed include conducting more detailed hydrological and hydraulic analysis, integrating with other flood disaster mitigation strategies, and developing a comprehensive flood disaster mitigation plan for the Belawan watershed.

Q: What are the limitations of the study?

A: The limitations of the study include limited data availability and simplification of flood dynamics.

Q: What are the conclusions of the study?

A: The conclusions of the study are that the potential for flooding in the Belawan watershed is very significant, and that increasing the capacity of river infrastructure, constructing an early warning system, and implementing community education and awareness programs on the dangers of flooding become important steps to minimize the negative impact of flooding in the region.

Q: What are the implications of the study?

A: The implications of the study are that flood disaster mitigation strategies should be implemented in the Belawan watershed to minimize the negative impact of flooding on the community and infrastructure.

Q: What are the recommendations for policymakers?

A: The recommendations for policymakers are to implement flood disaster mitigation strategies in the Belawan watershed, including increasing the capacity of river infrastructure, constructing an early warning system, and implementing community education and awareness programs on the dangers of flooding.

Q: What are the recommendations for researchers?

A: The recommendations for researchers are to conduct more detailed hydrological and hydraulic analysis, integrate with other flood disaster mitigation strategies, and develop a comprehensive flood disaster mitigation plan for the Belawan watershed.

Q: What are the recommendations for the community?

A: The recommendations for the community are to be aware of the dangers of flooding and to take necessary precautions to minimize the negative impact of flooding on their lives and property.