Pengembangan Model Faveur untuk Penilaian Kriteria Retensi pada Green Roof di Perancis

Abstract

Pemanfaatan green roof meningkat secara signifikan selama 10 tahun terakhir di Prancis. Tidak terumuskannya kriteria hidrologis untuk merancang dan mengevaluasi pemanfaatan green roof untuk pengelolaan air hujan khususnya di Prancis menjadi masalah tersendiri. Tujuan dari penelitian ini adalah untuk mengembangkan sebuah tools dalam model FAVEUR untuk menilai kinerja kriteria retensi green roof. Dalam penelitian ini criteria retensi green roof dihitung dalam 3 skala waktu yaitu tahunan, musiman dan setiap kejadian hujan. Simulasi model FAVEUR dengan variasi parameter untuk ncalc=500 menqhasilkan nilai kriteria retensi rata-rata: tahunan antara 301-470 mm (48-75% dari curah hujan tahunan), retensi musim panas antara 218-327 mm (35-52% dari curah hujan tahunan), retensi musim dingin antara 84-143 mm (13-23% dari curah hujan tahunan). Selanjutnya untuk kriteria retensi kejadian hujan, nilai maksimum selalu berbanding lurus dengan kapasitas retensi dalam interval 12-100 mm, nilai minimum selalu sama dengan 0 dan rata-rata antara 5.13-44.46 mm. Kriteria retensi ini menunjukkan korelasi yang baik dengan kapasitas intersepsi (Cint). Berdasarkan korelasi tersebut, disusunlah 48 persamaan polinomial kriteria retensi dalam tiga skala waktu berbeda. Selanjutnya, berdasarkan hubungan kriteria retensi green roof dan karakteristik fisik green roof terhadap kapasitas intersepsi, sebuah tools penilaian kinerja hidrologis green roof telah berhasil disusun dalam format Excel©. Tools ini dapat menunjukkan kinerja hidrologis green roof khususnya kriteria retensi dengan memvariasikan karakteristik fisik green roof seperti jenis vegetasi, ketebalan substrat dan kapasitas air maksimum substrat (CME).

Utilization of green roof has increased significantly in the last ten years in France. The lack of green roof’s hydrological criterias to evaluate its performance in France especially is still a problem. The purpose of this study was to develop an assessment tools in FAVEUR model for predicting the green roof performance in managing rainfall excess in urban areas, especially in retention criteria. In this research, the retention criteria (Ab) was calculated for different time-scales; annual, seasonal and rain-event. The simulation of FAVEUR parameters variation with ncalc=500 showed the average of annual retention were between 301-470 mm (48-75% of annual rainfall), summer retention were between 218-327 mm (35-52% of annual rainfall) and winter retention were between 84-143 mm (13-23% of annual rainfall). Then for rain event time scales, the maximum retention were constantly linear with interception capacity in interval 12-100 mm, the minimum retention were continuously equal0 and the average retention were between 5.13-44.46 mm. These results showed a good correlation with the interception capacity (Cint). According to these correlations, the 48 polynomial equations were created in the three times-scales. Based on the correlation between green roof retention critera and physical characteristic to interception capacity, the green roof’s hydrological tools were developed on an Excel© sheet. This tools presented the hydrological performance of green roof especially the retention criteria by varying physical characteristics of green roof such as the type of vegetation, the thickness of the substrat and the water maximum capacity of the substrat (CME).