Dinamika Kualitas Air Pada Berbagai Penggunaan Lahan Di Sub DAS Cisadane

Abstract

Cisadane river flows from Bogor Regency to Jakarta through to Bogor City. This river is utilized for many kind of human activities like as agriculture, fisheries, industry, tourism and also household activity. The utilization of water resources due to environmental problems such as decreasing of water quality. Decreasing of water quality is mainly happened on the river channel. This condition caused by level of activities (urban sattlements) are intensive. Therefore, the assessment and study of river water quality at Cisadane must be done. This research aimed to identify water quality of bogor cisadane river in variety of landuse from upstream to downstream. In additon, water samples were taken by representative composition of landuse and different types of soil. The parameters were analysed consist two parameters, physical parameter and chemical parameter. The analysis of phisycal parameters were temperature and total dissolved solids (TDS). The analysis of chemical parameters were pH, biochemical oxygen demand (BOD), NO3, PO4, and Pb. The data were descriptive analyzed by compared the field observation data with the data of water quality standart according PP No. 82/2001 about water quality management and water pollution control. The results showed that the water quality of cisadane in around upstream river tent to better than the midstream to downstream river. BOD and Phosphate content of upstream river were lower than downstream river showed by 5.04 up to 7.87 mg/l BOD and 0.01 up to 0.02 mg phosphate/l in the upstream river, 10.17 up to 23.61 mg/l BOD and 0.03 up to 0.07 mg/l phosphate in the downstream river. In addition, water quality after the rain (high discharge) were better than not rain (low discharge). It showed by parameter of temperature and BOD were lower. Parameters of water quality were appropriate all grade of water quality standart (PPRI No. 82/2001) showed by temperature , pH, and Phosphate parameters. Parameters of TSS and BOD were included into third and fourth grade of water quality standart, meanwhile NO3- and Pb were included into all grade of water quality in some research location.

Sungai Cisadane yang mengalir dari Kabupaten Bogor ke Jakarta melalui Kota Bogor banyak dimanfaatkan untuk berbagai macam kegiatan manusia seperti pertanian, perikanan, industri, pariwisata dan juga keperluan rumah tangga. Akibat pemanfaatan sumberdaya air tersebut maka muncul berbagai permasalahan lingkungan diantaranya adalah menurunnya kualitas air. Penurunan kualitas air terutama terjadi pada sungai/alur sungai dengan tingkat kegiatan yang intensif seperti pemukiman kota. Sehubungan dengan hal-hal tersebut, maka perlu diadakan pengkajian dan penelaahan terhadap kualitas air Sungai Cisadane. Penelitian ini bertujuan untuk mengetahui kualitas air sungai Cisadane Bogor. Pengambilan contoh air dilakukan di lima lokasi yang mewakili komposisi penggunaan lahan. Parameter yang diamati meliputi parameter fisika, yaitu suhu dan total padatan tersuspensi (TSS) dan parameter kimia yang meliputi pH, kebutuhan oksigen biokimiawi (BOD), serta kandungan nitrat, fosfat dan timbal. Data yang diperoleh dianalisis secara deskriptif dengan membandingkan data hasil analisis terhadap data standar baku mutu air menurut PP No. 82 Tahun 2001 tentang pengelolaan kualitas air dan pengendalian pencemaran air. Hasil penelitian menunjukkan bahwa kualitas air Cisadane di sekitar hulu cenderung lebih baik dibandingkan di tengah-hilir. Aliran sungai di hulu memiliki kandungan BOD (5.04-7.87 mg/l) dan fosfat (0.01-0.02 mg/l) lebih rendah dibandingkan daerah hilir dengan kandungan BOD (10.17-23.61 mg/l) dan fosfat (0.03-0.07 mg/l). Selain itu, kualitas air sesaat sesudah hujan (debit tinggi) lebih baik yang ditunjukkan dengan nilai suhu dan BOD lebih rendah dibandingkan dengan saat tidak ada hujan (debit rendah). Parameter kualitas air yang memenuhi baku mutu air menurut PPRI No. 82 Tahun 2001 disemua kelas diantaranya parameter suhu, pH dan fosfat. Parameter TSS dan BOD hanya memenuhi baku mutu air kelas tiga dan empat, sedangkan nitrat dan timbal memenuhi semua kelas baku mutu air hanya di beberapa lokasi penelitian.