Flownet dan Kegunaannya

Cara Interpolasi membuat flownet

Flownet atau yang lebih dikenal dengan sebutan kontur air tanah dapat dibuat dengan cara interpolasi data-data elevasi muka air tanah yang teridentifikasi di suatu daerah. Untuk membuat flownet ini diperlukan beberapa data, seperti data tinggi muka air tanah (TMA) data elevasi sumur, dan koordinat titik-titik pengukuran. Flownet ini dapat menunjukkan beberapa informasi dari variasi kerapatan kontur yang dihasilkan. Dari flownet tersebut dapat diperoleh informasi arah aliran air tanah, daerah re-charge, daerah discharge, debit air tanah, dan kemiringan muka air tanah ( hydraulic gradient).

Metode-Metode Investigasi Air Tanah

Keterdapatan air tanah di dalam bumi tidak bisa kita lihat langsung di permukaan tanah, tetapi keberadaan, potensi dan karakteristiknya dapat diketahui dengan mengaplikasikan beberapa metode investigasi air tanah. Secara garis besar, ada dua jenis investigasi air tanah yaitu investigasi dari permukaan tanah dan investigasi di bawwah permukaan tanah.Investigasi daari atas pemukaan tanah teridir dari :

Mataair (Spring) dan Klasifikasinya

mata air dari pegunungan everest.

Mataair (spring) adalah pemusatan pengeluaran air tanah  yang muncul di permukaan tanah sebagai arus  dari aliran air. Mataair berbeda dengan rembesan (seepage). Rembesan merupakan mataair yang keluar secara perlahan-lahan dan menyebar pada permukaan tanah. Keadaan mataaair sangat bervariasi. Menurut Tolman (1937), faktor-faktor yanng mempengaruhi mataair diantaranya :

Material Batuan Pembentuk Aquifer

Berbagai formasi geologi dapat berfungsi sebagai aquifer. Formasi geologi tersebut diantaranya endapan aluvial, batu gamping, batuan vulkanik, batu pasir serta batuan beku dan batuan metamorf.

• Endapan Aluvial

Sekitar 90% airtanah terdapat pada material lepas yaitu kerikil dan pasir (Purnama, 2000). Berdasarkan cara terbentuknya akuifer di daerah ini dapat dibagi menjadi 4 kategri yaitu :

Air Tanah

Airtanah mempunyai peranan penting dalam kehidupan manusia, karena 96% air tawar di bumi merupakan air tanah. Sumber utama airtanah adalah air hujan yang meresap ke dalam tanah dan mengikuti proses yang disebut siklus hidrologi. Ilmu yang mempelajari air tanah adalah geohidrologi, didukung oleh ilmu ilmu lain seperti geologi, geomorfologi, geokimia, ilmu tanah bahkan radiologi.

The Relationship between Groundwater and Surface Water

It is traditional to think of groundwater sustaining streamflows during the summer months, which indeed it often does. However, the interaction between groundwater and streamflow is complex and depends very much on local circumstances.

Aquifers and Aquitards

kind of aquifer

An aquifer is a layer of unconsolidated or consolidated rock that is able to transmit and store enough water for extraction. Aquifers range in geology from unconsolidated gravels such as the Yogyakarta aquifer in the Indonesia to distinct geological formations (e.g. chalk underlying Gunung Kidul

ACID RAIN AND GROUND WATER PH

An important measure of water quality is its pH. The letters (pH) describe the acidic or basic nature of a substance. Scientifically a liquid’s pH is a measure of the concentration of hydrogen ions (H+ ) it contains. The Danish biochemist S.P.L. Sorenson originally proposed the concept or the pH scale in 1909 as a method to describe the “acidity” of beer.

The pH scale ranges from 0 to 14 with a value of 7 indicating a neutral pH (neither acidic nor basic]. Distilled water has a pH of 7. Basic (or alkaline) solutions (i.e. bleach and ammonia) have values greater than 7. Acidic solutions (i.e. battery acid, lemon juice, and vinegar) have values less than 7. Each unit change in pH is equal to a 10-fold (10 times) change in the pH. The table shows the approximate pH value for some common substances. Rain and snow (the principal sources of ground water) have pH values near 5.6, if they are relatively free of pollution. However, in many areas of the United States “acid rain” is now the norm because of pollution emissions from sources such as coal-fired power plants and car exhaust. Acid rain can have pH value near 4. There are concerns that acid rain is having effects on vegetation and aquatic fauna. Once on the ground, some of the acidic precipitation infiltrates downward to mix with ground water and can affect the ground water pH.

RAIN WATER HARVESTING AND ARTIFICIAL RECHARGE TO GROUND WATER

WHAT IS RAIN WATER HARVESTING ?

The principle of collecting and using precipitation from a catchment surface. An old technology is gaining popularity in a new way. Rain water harvesting is enjoying a renaissance of sorts in the world, but it traces its history to biblical times. Extensive rain water harvesting apparatus existed 4000 years ago in the Palestine and Greece. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water to augment water from city's aqueducts. As early as the third millennium BC, farming communities in Baluchistan impounded rain water and used it for irrigation dames, build of stone rubble, were found in Baluchistan and Kutch in Gujarat in India.

ARTIFICIAL RECHARGE TO GROUND WATER

Artificial recharge to ground water is a process by which the ground water reservoir is augmented at a rate exceeding that obtaining under natural conditions of replenishment. Any man-made scheme or facility that adds water to an aquifer may be considered to be an artificial recharge system.