Citra Sentinel-2 untuk Pemetaan Kawasan Sabuk Hijau dan Sedimen Tersuspensi di Waduk Sermo Yogyakarta

Ferizta Hardika Putri, Ir. Emma Soraya, S.Hut., M.For., Ph.D., IPU; M. Chrisna Satriagasa, S.Si., M.Ec., Dev.

2026 | Skripsi | KEHUTANAN

Sedimentasi merupakan ancaman utama bagi keberlanjutan fungsi waduk sebagai infrastruktur sumber daya air, di mana sedimen yang terangkut dari daerah tangkapan air terus terakumulasi dan mempercepat berkurangnya umur guna waduk. Salah satu pendekatan untuk mengendalikan laju sedimentasi adalah keberadaan zona penyangga riparian atau kawasan sabuk hijau di sekitar badan air, sebagaimana terdapat di Waduk Sermo. Meskipun demikian, waduk ini masih menghadapi ancaman laju sedimentasi yang tnggi. Penelitian ini bertujuan memetakan kerapatan vegetasi kawasan sabuk hijau, memetakan sebaran konsentrasi sedimen tersuspensi, serta menganalisis pengaruh kerapatan terhadap konsentrasi sedimen tersuspensi di Waduk Sermo menggunakan Citra Sentinel-2.  

Kerapatan vegetasi diestimasi melalui indeks Normalized Difference Vegetation Index (NDVI) dengan validasi Canopy Cover Index dari GlaMa, sedangkan sedimen tersuspensi diestimasi dengan parameter Total Suspended Solid (TSS) menggunakan C2RCC yang dioptimasi melalui penyesuaian parameter TSMfac, kemudian divalidasi dengan data lapangan berupa pengukuran tutupan tajuk dan sampel air. Pengaruh kerapatan vegetasi terhadap TSS selanjutnya dianalisis menggunakan regresi linear. 

Hasil penelitian menunjukkan sekitar tiga perempat kawasan sabuk hijau didominasi vegetasi lebat dengan rerata NDVI sebesar 0,63. Algoritma C2RCC Optimasi menghasilkan estimasi TSS rata-rata 6,22 mg/l mendekati nilai lapangan sebesar 6 mg/l dengan sebaran konsentrasi tertinggi berada di area tengah waduk akibat pengaruh musim peralihan hujan-kemarau. Model regresi liniear menunjukkan NDVI berpengaruh signifikan terhadap variasi konsentrasi TSS di badan air. Temuan ini menegaskan peran penting kawasan sabuk hijau sebagai zona penyangga dalam mengurangi masuknya sedimen tersuspensi ke Waduk Sermo.

Sedimentation is a major threat to the sustainability of reservoir functions as strategic water resource infrastructure, where sediment transported from the catchment area continues to accumulate and accelerates the reduction of the reservoir's service life. One approach to controlling the rate of sedimentation is the presence of a riparian buffer 

zone or green belt area surrounding the water body, as found in Sermo Reservoir. Nevertheless, this reservoir still faces a high threat of sedimentation rate. This study aims to map the vegetation density of the green belt area, map the distribution of suspended sediment concentration, and analyze the effect of vegetation density on suspended sediment concentration in Sermo Reservoir using Sentinel-2 Imagery. 

Vegetation density was estimated using the Normalized Difference Vegetation Index (NDVI), validated with the Canopy Cover Index from GLAMA, while suspended sediment was estimated through the Total Suspended Solid (TSS) parameter using C2RCC optimized by adjusting the TSMfac parameter, then validated with field data consisting of canopy cover measurements and water samples. The effect of vegetation density on TSS was further analyzed using linear regression.

The results showed that approximately three-quarters of the green belt area was dominated by dense vegetation, with a mean NDVI of 0.63. The Optimized C2RCC algorithm produced an average TSS estimate of 6.22 mg/l, close to the field value of 6 mg/l, with the highest concentration distribution found in the central area of the reservoir due to the influence of the rainy-to-dry season transition. The linear regression model showed that NDVI had a significant effect on the variation of TSS concentration in the water body. These findings confirm the important role of the green belt area as a buffer zone in reducing the input of suspended sediment into Sermo Reservoir

Kata Kunci : NDVI, TSS, C2RCC, Zona Penyangga, Buffer Zone