ABSTRAK

Air merupakan zat tunggal yang memiliki banyak kegunaan. Peran air bagi kehidupan sangat penting dalam pemenuhan kebutuhan hidup baik bagi manusia dan makhluk hidup lain. Air yang terdapat di alam dapat bersumber dari air laut, air hujan, air sungai dan mata air. Salah satu desa di Kecamatan Wonoayu adalah Desa Jimbaran Wetan. Letak Desa Jimbaran Wetan 30 km dari laut. Kondisi air tanah dangkal di Desa Jimbaran Wetan berdasarkan studi awal memiliki sebaran daya hantar berkisar pada angka terendah sebesar 324 µmhos/cm dan tertinggi 2.401 µmhos/cm. Penggunaan air tanah dangkal di Desa Jimbaran Wetan digunakan untuk konsumsi.

Jenis penelitian ini adalah deskriptif dengan populasi seluruh sumur di Desa Jimbaran Wetan. Menguunakan teknik pengambilan sampel grid sehingga didapat 9 sampel. Teknik pengumpulan data dengan pengukuran untuk memperoleh hasil daya hantar listrik. Menggunakan metode diagram trilinier piper untuk menganalisis fasies kimia air tanah dangkal serta penyebab keasinan air tanah dangkal.

Hasil dari analisis menggunakan metode diagram trilinier piper yaitu terdapat 3 jenis tipe kimia air tanah di Desa Jimbaran Wetan yaitu tipe NaCl, tipe CaHCO₃ dan tipe mix. Persebaran tipe kimia air tanah lebih besar ke arah Timur dengan tipe NaCl. Semakin ke Selatan maka air akan bersifat tawar karena telah terjadi pencucian senyawa Na.Tipe air tanah dangkal dapat dipengaruhi oleh jenis batuan akuifer serta perubahan fasies air tanah dangkal.

Penyebab keasinan air tanah dangkal di Desa Jimbaran Wetan Kecamatan Wonoayu Kabupaten Sidoarjo berdasarkan analisis menggunakan metode diagram trilinier piper yaitu air Natrium Klorida, yang merupakan ciri khas dari air tanah dasar laut dan dalam. Tipe CaHCO₃ dengan sifat air lebih tawar disebabkan karena terjadinya pencucian Natrium Klorida yang lebih intensif.. Serta air tanah dangkal tersebut tidak bisa digunakan untuk konsumsi karena beberapa kandungan yang melebihi batas yang ditentukan menurut Peraturan Menteri Kesehatan Republik Indonesia No.492/MENKES/PER/IV/2010.

Kata Kunci : air tanah dangkal, hidrokimia, diagram trilinier piper

ABSTRACT

The role of water for life is very important in subsistence both for humans and other living beings. Water found in nature can be sourced from sea water, rain water, rivers and springs. One of the villages in Wonoayu district is Jimbaran Wetan. Jimbaran Wetan is 30 km from the sea. The shallow groundwater conditions in the village of Jimbaran Wetan based on early study has a distribution range in the conductivity low of 324 μmhos / cm and the highest 2,401 μmhos / cm. The more water is capable of condusting electricity, the more salt is demosntrated contained in water.

The use of shallow ground water in the Jimbaran Wetan village used for consumption. Though there are 29 wells that have high electrical conductivity which is brackish water. Water is good for consumption one of the conditions there are not tasteless.This type of research is descriptive of the population of all the wells in the Jimbaran Wetan village. Using grid sampling technique that gained 9 samples. Measurement data collection techniques to obtain the results of electrical conductivity. Using the Piper Trilinear Diagram method for analyzing the chemical facies of shallow ground water and cause shallow groundwater salinity.

The results of the analysis method Piper Trilinear Diagram which is contained 3 types of ground water chemistry in the Jimbaran Wetan village namely the NaCl type, CaHCO₃ type and the mix type. Distribution of chemical types of groundwater is greater to the East with the NaCl type. Increasingly South to water will be fresh because it has happened laundering shallow groundwater Na. Shallow groundwater types can be affected by the type of aquifer rock as well as shallow groundwatter conversion.

 Causes of shallow groundwater salinity in the Jimbaran Wetan village Wonoayu subdistrict of Sidoarjo regency based analysis method is water Piper Trilinear Diagram Sodium Chloride, which are characteristic of the ground water and the sea floor. Type CaHCO₃ with more fresh water properties due to the leaching of sodium chloride is more intensive. As well as the shallow ground water can not be used for consumption because it contains Calcium, Sodium, Magnesium, Chloride and Sulfate in excess of the limit specified by the Indonesian Health Ministry Decree 492 / Menkes / PER / IV / 2010.

Keywords : Shallow groundwater, hydrochemical, Trilinear

Diagram Piper