| Measuring drought and drought impacts in Red Sea Province |
|1. Introduction to Red Sea Province|
The Red Sea Hills are located from Egypt to Eritrea in a belt that runs in a north-south direction from about 15 km west of the Red Sea coast to about 150 km inland. The highest peaks of the mountain range are found along the Eritrean border (9100 feet), northwest of 'Aruus at Jebel Oda (7412 feet), southwest of Muhammed Qul at Jebel Erba (7274 feet), and southwest of Halaib town at Jebel Asoteriba (7272 feet). West and southwest of the Red Sea Hills leading to the Nile and 'Atbara valleys are vast monotonous plains sometimes punctuated by tall solitary mountains.
The Red Sea Hills are part of the Red Sea Rift Valley formed by the divergent movement of the Arabian and the North African crustal plates. These plates, units of crust floating on a bed of heated, plastic mantle, are being pushed apart by the formation of new crust along the mid-Red Sea ridge, located at the bottom of the Red Sea aligned in a north to south direction.
The Red Sea Hills are commonly referred to as being composed of Pre-Cambrian crystalline rock. This means that the rock is of the oldest known on earth, formed in the geological era called the Pre-Cambrian over 570million years ago. The Red Sea Hills are composed principally of gneiss and granites shot through during more recent times by vertical wall-like structures of other igneous rock in what are termed "dykes" by geologists. Many dykes are easily visible on the surface. Particularly picturesque pink granite dykes are found along Khor Sitareb in
North Tokar District. Gold, mined in Red Sea Province since Pharaonic times, is found only in the dykes. Emeralds are also found in such formations, however, there are no currently working emerald mines in Red Sea Province. Columnar basalt is visible throughout the province particularly in the south and southwest.
There are two alluvial fans of note in the province located along the Red Sea coast: the Arba'at and Tokar deltas. The Arba'at delta is located just north of Port Sudan and the Tokar Delta is located 150 kilometres to the south of Port Sudan. Although both deltas are used for agriculture and pastoralism and provide a measure of security against adversity, the Tokar delta is by far the more important of the two resources. The delta soil is particularly rich. It has been estimated by the Tokar Board that an average of four inches (about 9 cm) of new silt is deposited on the delta every year. This reduces the necessity for the use of fertilisers in farming.