Pemodelan kualitas air sungai menggunakan QUAL2K :: Studi kasus Sungai Secang Kabupaten Kulon Progo Provinsi Daerah Istimewa Yogyakarta

BAIDOWI, Ahmad, Dr. Eko Sugiharto, DEA

2010 | Tesis | S2 Ilmu Kimia

Telah dilakukan pemodelan kualitas air sungai menggunakan QUAL2K berdasarkan data pengukuran yang meliputi oksigen terlarut (DO), temperatur air, pH, total padatan terlarut (TDS), daya hantar listrik (EC), total padatan tersuspensi (TSS) dan hidrolika sungai. Pengambilan sampel dilakukan pada bulan Mei (setelah hujan) dan bulan Juli (sebulan tidak hujan). Status kualitas air sungai diperoleh dengan membandingkan hasil pengukuran dan prediksi model terhadap baku mutu air. Kalibrasi model menggunakan data bulan Mei dan validasi model menggunakan data bulan Juli. Sensitifitas model diuji untuk mengetahui pengaruh perubahan temperatur udara, awan dan naungan pepohonan di tepian sungai terhadap temperatur air. Kualitas air Sungai Secang dari hasil pengukuran dan prediksi model dibandingkan dengan baku mutu air masuk kategori kelas I kecuali TSS pada bulan Mei. Hasil sensitifitas model menunjukkan bahwa naungan pepohonan dapat menurunkan temperatur air pada skenario hari terpanas. Aplikasi QUAL2K digunakan untuk mengetahui prakiraan dampak pembuangan limbah pabrik bioetanol sebesar 2.500 m3/hari terhadap kualitas air Sungai Secang. Pembuangan limbah pada bulan Juli dapat berdampak besar pada kualitas air. Penurunan konsentrasi limbah atau penambahan debit air dapat meningkatkan DO daerah hilir.

Research on the water quality along the Secang River has been conducted using QUAL2K according the measurements of total suspended solids (TSS), dissolved oxygen (DO), water temperature, pH, total dissolved solids (TDS), electrical conductivity (EC) and river hydraulics. Sampling has been conducted in May (after rain) and July (without rain). Status of river water quality is obtained by comparing the results of measurements and model predictions with water quality standards. Calibration of model using the data in May and validation of model using the data in July. Sensitivity of model tested for effects of changes in air temperature, cloud and trees shading on the bank of the river on water temperature. The results of measurements and model predictions of the Secang River compared with water quality standards into class I categories except TSS in May. The results of the sensitivity model shows that shade trees can decrease water temperatures on the hottest day scenario. QUAL2K application used to predict the impact disposal for 2500 m3/day effluent from bioethanol plant to Secang River’s water quality. Waste disposal in July may have a major impact on water quality. The effluent treatment until low concentration and flow augmentation can increase DO water at the downstream region.

Kata Kunci : Pemodelan,Kualitas air,QUAL2K,Sungai Secang, modelling, water quality, QUAL2K, Secang River