KAJIAN KARAKTERISTIK SEDIMEN SUNGAI YANG MASUK KE TELUK KENDARI SULAWESI TENGGARA

LAODE SAFIRUDDIN, Prof. Dr. Sudarmadji, M. Eng. Sc.

2013 | Tesis | S2 Ilmu Lingkungan

Karakteristik Daerah Aliran Sungai yang bermuara di Teluk Kendari sangat beragam utamanya bentuk morfometrinya. Morfometri pada setiap Daerah Aliran Sungai akan sangat mempengaruhi besarnya angkutan sedimen melayang pada suatu sungai. Sedimen melayang adalah sedimen yang bergerak melayang di atas dasar sungai dan terbawa bersama aliran air. Data besarnya angkutan sedimen melayang merupakan salah satu komponen informasi hidrologi selain banjir, kekeringan, dan potensi sumberdaya air. Penelitian ini bertujuan : 1. Mengetahui karakteristik DAS Wanggu, DAS Kambu, dan DAS Mandonga yang bermuara pada Teluk Kendari; 2. Mengetahui besar debit aliran sungai dan konsentrasi sedimen melayang pada aliran Sungai Wanggu, Sungai Kambu, dan Sungai Mandonga; dan 3. Menganalisis hubungan antara debit aliran sungai dengan debit muatan sedimen yang masuk ke Teluk Kendari. Penelitian ini menggunakan pendekatan deskriptif dan survei dengan melakukan observasi langsung di lapangan. Analisis peta RBI dilakukan untuk mengetahui morfometri DAS sedangkan observasi lapangan dilakukan untuk mengetahui kecepatan aliran sungai dan debit aliran serta analisis laboratorium untuk mengetahui tingkat konsentrasi sedimen. Data debit aliran dan konsentrasi sedimen merupakan data penting untuk mengetahui data debit sedimen melayang pada ketiga sungai yakni sungai Wanggu, Kambu, dan Mandonga. DAS Wanggu memiliki luasan 335,115 km2 dan 143 alur sungai dengan indeks kerapatan sebesar 1,15 km/km2, serta orde dan tingkat percabangan sungai sebesar 3,15. Debit aliran rata-rata di Sungai Wanggu yaitu 8,649 m3/detik, dengan kadar konsentrasi sedimen yaitu 1.731,5 mg/liter. Nilai koefisien korelasi debit aliran Sungai Wanggu dengan debit sedimennya sebesar 0,860. DAS Kambu memiliki luasan 22,3 km2dan 6 alur sungai dengan indeks kerapatan sebesar 1,05 km/km2, serta orde dan tingkat percabangan sungai sebesar 3,75. Debit aliran rata-rata di Sungai Kambu sebesar 0,605m3/detik dengan kadar konsentrasi sedimen yaitu 1.034,6 mg/liter. Koefisien korelasi debit aliran Sungai Kambu dengan debit sedimen Sungai Kambu sebesar 0,927. DAS Mandonga memiliki luasan 14,43 km2 dan 8 alur sungai dengan indeks kerapatan sebesar 0,76 km/km2, serta orde dan tingkat percabangan sungai sebesar 3,6. Debit aliran ratarata Sungai Mandonga sebesar 0,187 m3/detik dengan kadar konsentrasi sedimen yaitu 646,5 mg/liter. Nilai koefisien korelasi debit aliran sungai dengan debit sedimennya sebesar 0,928.

The characteristics of a watershed which empties into Kendari Bay are very diverse especially in the form of its morphometry. Morphometry in each watershed will greatly influence the contain of suspended sediment in a river. Suspended sediment is hovering over the river and carried with the flow of water. Data of the magnitude of contain of suspended sediment is one of the components of the hydrological information besides floods, droughts, and water resource potential. This study aims to: 1. Know the characteristics of Wanggu, Kambu, and Mandonga Watersheds; 2. Know the magnitude of flow discharge and sediment concentration on Wanggu, Kambu, and Mandonga rivers; and 3. Analyze the relationships between flow discharge and suspended sediment discharge which empties into Kendari Bay. This study uses a descriptive approach and surveys with direct observations in the field. The analysis of the map RBI was conducted to determine the morphometry of the watershed, while field observations were conducted to determine the speed of the river flow and flow debit as well as laboratory analysis was conducted to determine the level of sediment concentration. Data flow and sediment concentration are important data to determine the data of suspended sediment discharge on the three rivers namely Wanggu, Kambu and Mandonga. Wanggu watershed has an area of 335.115 km2 and 143 river basins with density index 1.15 km/km2, as well as the order and degree of the branching streams were 3.15. The average of flow debit in Wanggu river was 8.649 m3/second with the average sediment concentration 1.731,5 mg/liter. The value of correlative coefficient of flow discharge of Wanggu river with its suspended sediment discharge was 0.860. Kambu watershed has an area of 22.3 km2 and 6 river basins with index density 1.05 km/km2, as well as the order and degree of the branching streams were 3.75. The average of flow discharge in Kambu river was 0.605 m3/second with the level of sediment concentration 1.034,6 mg/liter. The value of correlative coefficient of flow discharge of Kambu river with its suspended sediment discharge was 0.927. Mandonga watershed has an area of 14.43 km2 and 8 river basins with density index 0.76 km/km2, as well as the order and degree of the branching streams were 3.6. The average of flow discharge in Mandonga river was 0.187 m3/second with the average sediment concentration 646.5 mg/liter. The value of correlative coefficient of flow discharge of Mandonga river with its suspended sediment discharge was 0.928.

Kata Kunci : Morfometri DAS, Konsentrasi Sedimen, Debit Aliran, Debit Sedimen Melayang