River water quality modelling in Barito watershed

Abstract

Barito River becomes one of the biggest river in Indonesia. It is located between Central Kalimantan Province and South Kalimantan Province, which is its length of 900 km and Barito watershed covers area approximately 46,500 km2. Based on Presidential Decree No. 9 in 1999 about the identification of river crisis (IPA > 0.5 and Coefficient of Variation (CV) > 0.4), so Barito River can be classified into watershed crisis (priority - 2). Based on evaluation in 40 rivers during 1995-2000 with parameters biological oxygen demand (BOD), chemical oxygen demand (COD), and dissolve oxygen (DO) concentration, there is only one river which is not contaminated. That is Jeneberang River in Lebang Regency, South Sulawesi. Compared to this conditions, Barito River can be classified as a slightly contaminated river. Based on this experiment, the DO concentration was 4.74 mg.l−1 – 5.36 mg.l−1 less than the standard value 6 mg.l−1, BOD was approximately 2.68 mg.l−1 – 4.05 mg.l−1 above threshold 2 mg.l−1. In the other hand, COD aboved the standard 10 mg.l−1 were approximately 20.5 mg.l−1 – 30.1 mg.l−1. Almost all of the metal concentration in the rivers had a high value above standard deviation. In other hand, some of this parameter also had a value above standard deviation. Those were the acidity degree (pH), suspendable substances (TSS), BOD5 and Phosphat (PO4).