Water Quality of Batang Ai and Engkari River compared to Batang Ai Reservoir

• Main Author: Nik Nabilah, Nik Husni
• Format: Final Year Project Report
• Language: English
• Published: Universiti Malaysia Sarawak, (UNIMAS) 2014
• Subjects: GE Environmental Sciences
• Online Access: http://ir.unimas.my/id/eprint/34027/2/Nik%20Nabilah%20Ft.pdf; http://ir.unimas.my/id/eprint/34027/

Batang Ai Hydroelectric Reservoir is downstream of the confluence of two rivers, which are Batang Ai River and Engkari River. Over 20 years it has been constructed, the water quality status of the dam, particularly the tributaries, in the literature is scarce. Therefore, this study was carried out to determine the water quality status at different locations of both upstream of Batang Ai and Engkari River, and its confluence. The study was done on November 2013 (dry season) and March 2014 (rainy season). It yielded results that showed higher mean pH ranging from 7.12 to 7.39 during dry season and low water level. Dissolved oxygen (DO) showed higher value on rainy season (7.6-9.5 mg/L) at the upstream of both creeks compared to the confluence (1.7-9.1 mg/L). BODS was the lowest during dry season (1.3-6.4 mg/L) with low water level. Total suspended solids complied with Class I standards for both trips. The concentration of total phosphorus was higher during dry season ranged from 55.4 pg/L to 110.9 μg/L. Ammoniacal nitrogen concentration was slightly higher during dry season (0.26-1.20 mg/L), and the highest was at upstream of Batang Ai river (1.20 mg/L). Total sulfide concentration ranged from 0.04 to 6.90 mg/L and 0.39 to 11.52 mg/L in November 2013 and March 2014 respectively. Water Quality Index (WQI) for both trips complied with Class III standards. According to WQI, compared to the rivers, the confluence which is in the reservoir area is polluted at 20m depth. Overall, the concentration of every parameter measured was dependent on season and water level. Household wastewater and agricultural run-off from residential area alongside the rivers also contributed to the status of water quality of the reservoir and the rivers.