EVALUASI SISTEM DRAINASE DAN PENERAPAN STRATEGI HIJAU UNTUK MITIGASI BANJIR DI PERUMAHAN JATISARI ASRI BSB KECAMATAN MIJEN, KOTA SEMARANG

ABSTRAK

Perkembangan kawasan permukiman di perkotaan sering diiringi
peningkatan luas lahan terbangun yang kedap air, sehingga berkurangnya area resapan alami menyebabkan volume limpasan permukaan meningkat dan sistem drainase eksisting tidak selalu mampu menampung debit banjir. Kecamatan Mijen, khususnya Perumahan Jatisari Asri BSB, menjadi salah satu kawasan yang
langganan banjir, dengan kejadian banjir signifikan terjadi pada Januari 2024. Penelitian ini bertujuan mengevaluasi kinerja sistem drainase eksisting di RW 06 Perumahan Jatisari Asri BSB, menilai kontribusi infrastruktur hijau berupa biopori
dan sumur resapan dalam mitigasi banjir, serta merumuskan rekomendasi sistem drainase optimal melalui kombinasi pendekatan konvensional dan hijau. Penelitian dilakukan dengan pendekatan kuantitatif-evaluatif menggunakan data sekunder dan
analisis hidrologi. Evaluasi sistem drainase eksisting mengidentifikasi tiga saluran (2, 3, dan 8) yang tidak mampu menampung debit banjir rencana, dengan kapasitas eksisting masing-masing 0,291 m3/s; 0,168; dan 0,256 m3/s dibandingkan debit rencana 1,225; 0,275; dan 0,419 m3/s. Simulasi penerapan infrastruktur hijau menunjukkan penurunan debit limpasan menjadi 1,207; 0,262; dan 0,404 m3/s, menunjukkan manfaat tetapi belum cukup untuk memenuhi kapasitas. Perencanaan
kombinasi strategi hijau dan pelebaran saluran meningkatkan kapasitas menjadi 1,479; 0,310; dan 0,446 m3/s, sehingga seluruh saluran mampu menampung debit banjir rencana. Hasil ini menunjukkan bahwa integrasi antara sistem drainase konvensional dan strategi hijau merupakan solusi efektif untuk mitigasi banjir di Perumahan Jatisari Asri BSB, sekaligus memberikan manfaat tambahan seperti peningkatan resapan air tanah dan ruang terbuka hijau. Strategi kombinasi ini dapat menjadi rujukan bagi pengelolaan air hujan adaptif dan berkelanjutan di kawasan permukiman perkotaan.

Kata kunci : Sistem drainase, infrastruktur hijau, biopori, sumur resapan, mitigasi banjir, Perumahan Jatisari Asri BSB

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ABSTRACT

The development of residential areas in urban areas is often accompanied by an increase in the area of impermeable built-up land, so that the reduction of natural infiltration areas causes the volume of surface runoff to increase and the existing drainage system is not always able to accommodate flood discharge. Mijen Sub-district, especially Jatisari Asri BSB Housing, is one of the areas that is subject to flooding, with a significant flood event occurring in January 2024. This research aims to evaluate the performance of the existing drainage system in RW 06 Jatisari Asri BSB, assess the contribution of green infrastructure in the form of biopores and infiltration ponds in flood mitigation, and formulate recommendations for an optimal drainage system through a combination of conventional and green approaches. The research was conducted using a quantitative-evaluative approach using secondary data and hydrological analysis. Evaluation of the existing drainage system identified three channels (2, 3, and 8) that were unable to accommodate the planned flood discharge, with existing capacities of 0.291 m3/s; 0.168; and 0.256 m3/s compared to the planned discharge of 1.225; 0.275; and 0.419 m3/s, respectively. Simulations of green infrastructure implementation showed a decrease in runoff discharge to 1.207; 0.262; and 0.404 m3/s, showing benefits but not enough to meet capacity. Planning a combination of green strategies and channel widening increased the capacity to 1,479; 0,310; and 0,446 m3/s, so that the entire channel was able to accommodate the planned flood discharge. These results show that integration between conventional drainage systems and green strategies is an effective solution for flood mitigation in Jatisari Asri BSB Housing, while providing additional benefits such as increased groundwater recharge and green open space. This combination strategy can serve as a reference for adaptive and sustainable stormwater management in urban residential areas.

Keywords : Drainage system, green infrastructure, biopores, infiltration wells, flood mitigation, Jatisari Asri BSB Housing