Geological framework of Saudi Arabia groundwater resources

الملخص EN

Tectono-sedimentary units, containing major groundwater resources of Saudi Arabia, border the Arabian Shield on three sides.

They are the Tabuk Basin.

Wadi as Sirhan Basin.

Widyan Basin Margin, Northeast Interior Homocline, Arabian Gulf Margin.

East In- terior Homocline, Rub* al Khali Basin, and Wajid Basin.

These eight units, with thick perme- able clastic bodies, contain almost all the groundwater reserves of the Kingdom, conserva- tively estimated at 208 x HP m*.

Most basins contain multiple aquifers with huge amounts of good quality groundwater.

The Tabuk Basin aquifers are the thick Cambro-Ordovician Saq.

Ordovician-Silurian Lower.

Mid- dle.

and Upper Tabuk.

the Silurian Tawil.

and the Devonian Jauf.

Argillaceous aquicludcs separate these Lower Paleozoic sandstone aquifers.

The Wadi as Sirhan Basin contains productive Quaternary sands and less productive porous Quaternary volcanics and Paleogene chalks of the Hibr Formation.

The Mid-Cretaceous Sakaka Sandstone Aquifer, exposed on the Hail-Rutbah Arch, extends under the southeast- ern Wadi as Sirhan Basin.

In the Widyan Basin Margin joint Wasia-Biyadh Cretaceous aquif- ers are up to 650 m thick with abundant groundwater.

The Northeastern Interior Homocline has a sequence of Cambrian to Cretaceous aquifers (Saq.

Tabuk, Khuff.

Jilh.

Minjur, Dhruma.

Wasia-Biyadh and Aruma) dipping gently north- eastward off the Arabian Shield Along the southwestern margin of the Arabian Gulf Basin, good Tertiary aquifers, primarily the Umm er Radhuma, Dammam.

Hadrukh and Dam are utilized.

In the Eastern Interior Homocline.

the Jurassic Minjur-Dhruma and Cretaceous Wasia-Biyadh arc the main aquifers.

Throughout the Rub* al Khali, the Umm er Radhuma is the principal aquifer with a recently discovered shallow Neogene aquifer.

On the southern margin of the Arabian Shield, the dis- tinctive Cambro-Ordovician Wajid Sandstone forms an immense aquifer with groundwater re- serves of > 30 x 10 m3