Kajian Kualitas Air Sungai Code Propinsi Daerah Istimewa Yogyakarta

Abstract

ABSTRAK Status pencemaran dan beban daya tampung Sungai Code yang besar menunjukkan besarnya bahan pencemar yang masuk ke sungai, selain itu Sungai Code juga merupakan salah satu sungai yang terkena dampak aliran lahar din-gin Erupsi Gunungapi Merapi tahun 2010. Erupsi meningkatkan input sedimen dan debit air Sungai Code, serta men-gubah substrat dasar perairan. Tujuan penelitian ini : (1) Menganalisis kualitas air Sungai Code secara fisik dan kimia; (2). Membandingkan kualitas air Sungai Code pasca erupsi Merapi 2010 berdasarkan paramater pH, sulfida, dan besi total, dengan kondisi sebelum erupsi; (3). Menganalisis kondisi makrozoobentos pasca erupsi Gunungapi Merapi 2010, serta menganalisis pengaruh kualitas air sungai terhadap makrozoobentos; dan (4). Menganalisis kerugian ekonomi dan mengetahui persepsi terhadap sungai dari sebagian masyarakat yang memanfaatkan air sungai untuk irigasi pertanian dan perikanan keramba.Pengumpulan data dengan metode survei. Lokasi pengambilan sampel ditentukan secara pur-posive sampling yang mewakili kawasan bagian tengah Sungai Code (sebelum kota dan tengah kota), dan bagian hilir Sungai Code kawasan (setelah kota), meliputi setengah panjang Sungai Code. Sampel air dianalisis secara fisika kimia di Laboratorium. Sampel makrozoobentos diidentifikasi kemudian dianalisis dengan pendekatan kemelimpahan, dom-inansi, dan keragaman, serta regresi. Hasil wawancara untuk menilai persepsi masyarakat dan kerugian ekonomi akibat banjir lahar dingin dianalisis dengan crosstab. Hasil penelitian menunjukkan bahwa parameter DO, BOD, COD, dan ni-trat, tidak memenuhi baku mutu air kelas I di beberapa lokasi. Adapun kekeruhan, fosfat, dan sulfida, hampir di seluruh lokasi tidak memenuhi baku mutu. Menurunnya kualitas DO, BOD, COD, nitrat, dan fosfat disebabkan oleh limbah yang masuk ke sungai, sedangkan menurunnya kualitas sulfida dan kekeruhan, selain dari limbah juga disebabkan oleh erupsi Merapi. Makrozoobentos yang ditemukan di Sungai Code ada 5 genus yaitu Chironomous, Simulium, Ephemer-optera, Lymnaea, dan Tubifex. Suhu, kecepatan arus dan DO berpengaruh pada menurunnya keragaman dan dominansi bentos. Status Sungai Code pasca erupsi tercemar ringan berdasarkan indeks keragaman bentos = 1,69. Pendapatan masyarakat dari sawah dan perikanan keramba sungai pasca banjir lahar dingin menurun antara Rp.500.000,00-Rp. 2.000.000,00/ responden/ panen.

ABSTRACT Pollution status and load capacity of Code River which great shows total of pollutants entering the river, beside of the Code River also one of the affected rivers of lava Merapi Volcano Eruption at 2010. Eruption increase input of sediment and water discharge Code River and change the base substrate waters. The aim of this study: (1) Analyze the Code River water quality of physical and chemical; (2) Compare the Code River water quality after the eruption of Merapi in 2010 based on the parameters pH, sulfide, and total iron, with condition before the eruption; (3) Analyze the conditions of macrozoobenthos after eruption of Merapi Volcano in 2010, and to analyze the effect of water quality on macrozoobenthos; and; (4) Analyze the economic loss and know  perception of most people on the river water for agriculture irrigation and fishpond. Location of sampling is determined by purposive sampling to represent the central part of the Code River (before town and downtown), and the lower of the Code River (after city), include a half the length of the Code River. The water sampling were analyzed in the laboratory to examine quality water of chemical and physics. Macrozoobenthos sampling were identified and analyzed with the approach of abundance, dominant, and diversity, and regression. Results of interview to assess public perceptions and economic loss due to lava flood were analyzed by crosstab. The results show parameters of DO, BOD, COD, and nitrat. Results of interview to assess public perceptions and economic loss due to lava flood were analyzed by crosstab. The results show parameters of DO, BOD, COD, and nitrat, not comply with water quality standard of class I in some locations. Also, turbidity, phosphates and sulfides, nearly all locations not comply quality standards. Decrease of quality of DO, BOD, COD, nitrates, and phosphates were caused by waste into the river, while the declining quality of sulphide and turbidity, besides from waste also caused by eruption of Merapi. Macrozoobenthos were found in the River Code as genus as Chironomous, Simulium, Ephemer-optera, Lymnaea, and Tubifex. Temperature, current speed and DO effect on decreasing the diversity and dominance benthos. Status of Code River after eruption has polluted with the diversity index of benthic = 1.69. Income of farmer and fisherman of river after lava flood has descreasing between in IDR 500.000,00 until IDR 2,000,000.00 / respondent / harvest.