KAJIAN KUALITAS AIR DAERAH IRIGASI SEKAMPUNG BATANGHARI (Studi Kasus Pada Blok Tersier KBH1. Ki)

Asnal Diansyah, Prof. Ir. Joko Sujono, M. Eng., Ph.D.

2014 | Tesis | S2 Teknik Sipil

Pupuk kimia yang digunakan petani dan pengaruh hujan yang memiliki kandungan nitrogen pada lahan sawah di petak KBH1. Ki seluas 13 ha dapat memberi kontribusi pencemaran di saluran pembuang. Limpasan permukaan dari areal sawah mengandung pencemaran amonia, nitrit, nitrat, fosfat dan kalium. Penelitian dilakukan untuk mengetahui kontribusi pemupukan kimia terhadap kualitas air di saluran pembuang setelah terjadinya hujan. Metode yang digunakan adalah dengan pengukuran debit air dan pengambilan sampel air di saluran irigasi dan pembuang. Analisis Indeks Pencemaran dilakukan berdasarkan nilai kualitas air sehingga diperoleh status mutu air dan beban pencemaran pertanian. Analisis keseimbangan air dilakukan untuk mengetahui perubahan genangan yang terjadi di lahan sawah dan keseimbangan unsur hara akibat limpasan permukaan untuk periode 1 pada tanggal 10 Desember 2013, periode 2 pada tanggal 25 Desember 2013 serta periode 3 pada tanggal 9 Januari 2014. Konsentrasi dan beban pencemaran parameter pH, amonia, nitrit, nitrat, fosfat dan kalium cukup tinggi sesuai periode (waktu) yang ditinjau. Hasil analisis Indeks Pencemaran di saluran pembuang menunjukkan kondisi air tercemar ringan terutama pada periode 1 (satu). Akibat terjadinya hujan dan limpasan permukaan diperoleh perubahan genangan dari tinggi genangan harian sebesar 6.51 mm pada periode 1 (satu), 6.78 mm pada periode 2 (dua) dan 7.13 mm pada periode 3 (tiga). Pupuk Urea yang larut di saluran pembuang sebanyak 3.395 % dari total input Urea (air irigasi + pupuk + air hujan) sebanyak 146.883 kg yang terjadi selama 2 jam di periode 3 (tiga). Pencemaran pupuk TSP terbesar 0.357 % yang terjadi di periode 3 (tiga) selama 2 jam dari total input TSP (air irigasi + pupuk) sebanyak 195.717 kg, sedangkan pencemaran pupuk SP36 sebanyak 0.342 % dari total input SP36 (air irigasi + pupuk) sebanyak 260.916 kg yang terjadi selama 2 jam pada periode 3 (tiga). Pencemaran pupuk KCL sebanyak 3.757 % dari total input KCL (air irigasi + pupuk) sebesar 188.573 kg yang terjadi selama 2 jam pada periode 3 (tiga). Kata kunci: pupuk, saluran pembuang, indeks pencemaran, beban pencemaran pertanian.

Chemical fertilizer which used by farmers and the effect of rain which contain of nitrogen in the rice field plots KBH1. Ki area of 13 hectares can contribute to pollution in the drainage channel. Surface runoff pollution from rice fields containing amonia, nitrite, nitrate, phosphate and calium. The study was conducted to determine the contribution of chemical fertilizer on water quality in the drainage channel after the rain. The method used to measurement of water discharge and water sampling in the irrigation channel and drainage channel. Pollution Index based on analysis performed in order to obtain the value of the water quality status of water quality and agricultural pollution load. Water balance analysis was conducted to determine the changes that occur in the inundation of rice fields and the balance of nutrients due to runoff first period on December 10, 2013, second period on December 25, 2013 and third period on January 9, 2014. Concentration and pollution load parameters pH , ammonia, nitrite, nitrat, phosphate and calium high enough corresponding period ( of time ) are reviewed. The results of the analysis of pollution index in the drainage channel showed mild polluted water conditions, especially in the first period. Due to the occurrence of rainfall and surface runoff obtained from the puddle of water level changes daily at 6.51 mm in the first period, 6.78 mm in the second period and 7,13 mm in the third period. Urea fertilizier soluble in the drainage channel as much as 3.395 % of total input Urea (water of irrigation + rain water + fertilizer ) as much as 146.883 kg which occurred during a third period for 2 hours. TSP fertilizier pollution largest 0.357 % that occurred in third period for 2 hours of total input TSP (water of irrigation + fertilizer) of 195.717 kg, while SP36 fertilizier pollution as much as 0.342 % of the total input SP36 (water of irrigation + fertilizer) as many as 260.916 kg happened for 2 hours in third period. KCL fertilizer pollution as much as 3.757 % of the total input KCL (water of irrigation + fertilizer) of 188.573 kg which occurred during a third period for 2 hours. Keywords: fertilizer, drainage channel, index of pollution, agricultural pollution load

Kata Kunci : pupuk, saluran pembuang, indeks pencemaran, beban pencemaran pertanian.