What is an artesian well?

Arte­sian waters are pres­sur­ized ground­wa­ter occur­ring at sig­nif­i­cant depths (from 100 to 1,000 m) between two imper­me­able rock lay­ers.

An arte­sian well is a well drilled to exploit arte­sian waters. Water from such a well may flow to the sur­face nat­u­ral­ly with­out pumps, mak­ing it one of the most valu­able sources of drink­ing water world­wide.

Genesis of artesian waters

Arte­sian waters have an infil­tra­tion ori­gin and form over long geo­log­i­cal peri­ods as fol­lows:

• pre­cip­i­ta­tion or sur­face water infil­trates down­ward and fills pores and frac­tures in rocks;
• an imper­me­able lay­er (clays, shales, etc.) forms above the water-bear­ing stra­tum;
• con­tin­ued accu­mu­la­tion increas­es pres­sure, which under cer­tain con­di­tions caus­es nat­ur­al dis­charge to the sur­face.

Artesian basins

Arte­sian waters are com­mon­ly found in low­lands, basins, syn­clines, as well as in frac­tured crys­talline rocks and tec­ton­ic fault zones. Geo­log­i­cal struc­tures with alter­nat­ing aquifers and con­fin­ing lay­ers are referred to as arte­sian basins.

In Ukraine, the fol­low­ing arte­sian basins are dis­tin­guished:

• Dnieper–Donets Arte­sian Basin;
• Volyn–Podillia Arte­sian Basin;
• Black Sea Arte­sian Basin.

The upper ground­wa­ter hori­zons (up to 400–600 m in the north and 100–300 m in the south) con­tain fresh water used for water sup­ply. Deep­er hori­zons are char­ac­ter­ized by brack­ish to saline waters.

The Dnieper–Donets Arte­sian Basin cov­ers the Cherni­hiv, Kyiv, Sumy, Kharkiv, Polta­va, Dnipropetro­vsk, Donet­sk, and Luhan­sk regions of Ukraine and con­tains about half of the country’s ground­wa­ter reserves.

Aquifers are rep­re­sent­ed by Devon­ian to Qua­ter­nary sed­i­men­ta­ry rocks occur­ring at depths of 300–800 m (some­times up to 1,000 m).

• rock types: sands, sand­stones, lime­stones, marl–chalk deposits;
• aquifer thick­ness: 40–80 m;
• hydraulic head: up to 800 m;
• trans­mis­siv­i­ty: from 20–30 to 300–1,000 m³/day;
• well yield: 15–55 L/s;
• water min­er­al­iza­tion: 1–3 g/L.

The Volyn–Podillia Arte­sian Basin cov­ers the Volyn, Rivne, Ternopil, Khmel­nyt­skyi, and Lviv regions.

• fore­cast ground­wa­ter resources: about 13 mil­lion m³/day;
• main reserves con­cen­trat­ed in the Upper Cre­ta­ceous aquifer;
• actu­al abstrac­tion: about 1 mil­lion m³/day.

The Black Sea Arte­sian Basin is locat­ed with­in the Black Sea depres­sion and is char­ac­ter­ized by a com­plex hydro­ge­o­log­i­cal struc­ture.

• waters occur in Qua­ter­nary, Neo­gene, Pale­o­gene, and Cre­ta­ceous deposits;
• for­ma­tion of saline waters and brines is typ­i­cal;
• min­er­al­iza­tion may exceed 10–30 g/L;
• waters often con­tain ele­vat­ed bromine and iodine con­cen­tra­tions.

The Neo­gene aquifer is the main source for domes­tic and drink­ing water sup­ply.

Use of artesian waters

Arte­sian waters are wide­ly used in prac­tice:

• drink­ing water sup­ply in com­pli­ance with state san­i­tary stan­dards;
• irri­ga­tion and water­ing of agri­cul­tur­al lands;
• tech­no­log­i­cal water sup­ply for indus­tri­al enter­pris­es;
• use in geot­her­mal ener­gy sys­tems;
• fill­ing of ponds, reser­voirs, and oth­er water bod­ies.