Abstract

Human activities in water-based tourism areas may contribute to the degradation of the water quality. This research aimed to evaluate the surface water quality by using accurate biotic index of benthic macroinvertebrates as a bioindicator in Coban Rondo water river in Pujon, Malang Indonesia. Three locations including upstream, waterfall, and downstream were the sources of the macroinvertebrate samples taken in two different periods during the dry season in 2017 and the rainy season in 2018. The research was conducted from August 2017 to October 2018. Benthic macro-invertebrate sampling was conducted in each site. Results indicated that the pH of the water in Coban Rondo ranges from 6.5 to 7.5. The electrical conductivity is found higher during rainy season than dry season. Similarly, the (Biochemical Oxygen Demand) BOD level is also significantly higher in the rainy season. Meanwhile, the level of (Chemical Oxygen Demand) COD and (Dissolved Oxygen) DO are varied with the COD level found higher in the waterfall during rainy season but downstream in the dry season. The DO level is still acceptable based on the (Food and Agriculture Organization) FAO level of agricultural and drinking water. Moreover, the bioindicator results show that there are 32 species of macroinvertebrates, with average total abundance of 1662 organisms/m². Majority of the macroinvertebrates are Uenoidae, Hydropsychidae, and Baetidae which belong to taxa tolerance 1 – 4. Additionally, only waterfall station which is dominated by Caenidae with the tolerance of 7. Therefore, the water quality in Coban Rondo waterfall ranges from significantly polluted in the waterfall station to very good and excellent quality in general condition. There are a total of 140 taxa recorded in this study, including 80 taxa during the rain season and 60 taxa in the dry season and a difference in the total macroinvertebrate abundance in two seasons with a sharp fluctuation found during dry season. The Shannon Wiener diversity shows an average index of above 2 which indicates that the water has good quality and not polluted.

Keywords: Coban Rondo, Macroinvertebrate, Bioindicator, Water quality, Waterfall

Abstract. Coban Rondo waterfall is threated to have been polluted due to the tourism activity. Analysis of the water quality is essential to provide the basis for judging the suitability of water for its designated uses and improving its conditions. This study aims to analyze the water physical and chemical parameters of Coban Rondo waterfall in Pujon, Malang Indonesia. Three locations including upstream, waterfall, and downstream were the sources of the water samples taken during the rainy season. The study analyzes 12 water quality parameters consisting of 5 physical parameters and 7 chemical parameters. Using ANOVA, cluster analyses, and Biplot to analyze the water quality, the research results indicated that water and air temperatures were high in the upstream. The value of pH from 6.9 to 7.4, DO from 8 to 11 mg/L, conductivity from 0.106-0.112dS/m, turbidity 3.3 NTU to 7.6 NTU, water debit4 x 105 L/s and total phosphate from 0.5to 0.07 mg/L were higher in the downstream area, while the concentration of nitrate from 5 to 30 mg/L, orthophosphate 1.0 to 1.4 mg/L, COD from 14 to 22 mg/Land BOD 10.8 to 15.6mg/L was highest in the upstream. It indicates that the human activity in Coban Rondo has affected the water quality. Based on Indonesia government regulation No. 82/2001, the water in Coban Rondo was still suitable for irrigation and tourism (Class II), except BOD level.

Keyword: Coban Rondo waterfall, physical chemical parameters, water quality.