Distribution of Saline Arid Zones (With Diagram)

After reading this article you will learn about distribution of saline arid zones.

1. India:

In India near Calcutta in deltaic area of Hugli river, the swamp region is known as Sunderbans. The Sunderbans, crisscrossed by creeks and channels of varying width and depth and subject to the fullest furies of the cyclone storms (fig. 25.2).

The Sunderbans is a tropical humid forest belt stretching from the Hoogly river on the west to the Maghna river (Bangladesh) on the east (Fig 25-3). The forest spreads over the Gangetic delta which is low, flat and alluvial and is intersected from north to south by several wide rivers; viz.. , Hariabhanga, Gusaba, Matla, Thakuran, Saptamukhi and Muriganga and numerous winding sluggish creeks, with saline water due to tidal influences.

Champion and Puri (1968) on the basis of studies of Sunderbans divided the Indian tidal forests into five types while Rao and Sastry (1974) classified them on an ecological basis into the estuarine (with constant influence of tides and fresh water) and pro-estuarine (with a lot of mixing of sail and freshwater leading to the growth of salt tolerant species).

The total area of mangroves in India to be 3564 sq. km. the largest areas being in West Bengal (Gangatic Delta) with 2000 sq. km. and Andaman and Nicobar with 1000 sq. km.

It may be of interest to point out here that high saline soils are not necessarily restricted to ocean or sea coasts only. In many hot deserts of India, far away from any sea coasts, the soil is distinctly saline due to the presence of NaCl, CaSO₄ etc.

The origin of high salinity of these desert soils is not clear but it may be due to:

i. Weathering of rocks

ii. Salts brought about by wind from neighbouring salt concentrations.

iii. Regional leaching and concentrations.

Saline soils occur in India in association with the normal zonal soils of desert and semi-desert regions.

The four major tracts where salt affected soils met within India are:

Rajasthan desert is comprised of saline unproductive land in the form of Saline lakes, salt depressions swamps and saline land.

Saline tract of Rajasthan hot desert can be divided into two regions:

i. Salt lakes e.g. Sambhar, Deedwana and Kuchaman.

ii. Salt basins e.g. Lunkaransar, Pachpadara, Bap, Phalodi, Pokaran, Thob, Tal Chhapar, Khaiuwala.

Salinization is not only one of the leading causes of desertification, but is also one of the most frustrating results of man’s attempts to expand cultivation into desert and semi-desert regions.

2. Australia:

The salinized brown soils cover large areas of Western Australia, Victoria and N. S. Wales. In the irrigation districts of N. S Wales, Victoria and South Australia because of the rising water table, large, areas have turned saline (Fig. 25.1).

3. Egypt:

With the introduction of permanent irrigation in tin- Nile Valley, salinization set in, in different areas. A recent survey has been shown that 150000 ha areas have turned saline.

4. Hungary:

The extent of saline lands is about half a million hectare. Almost all of these areas lie in the Great Hungarian Plain.

5. U.S.S.R.:

In the U.S.S.R., the saline tract comprises nearly 3-4% of the land area or 75 million hectares, in the irrigated areas of the Central Asian Soviet Republics of Uzbekistan, Tajikistan, Kazakhstan, Azerbaijan, Georgia and Turkmenia saline soils are most common.

6. North America:

In the South Western region due to non- provision of drainage about 1,50,000 hectares have been turned saline. This can best be observed in San Joaquin, Sacramento, Coachella and Imperial Valleys of California where irrigation has been provided on an extensive scale.

In the arid tracts of Utah and Nevada in the Great Basin, such soils occur in the depressions where the salts tend to accumulate as a natural consequence of the inadequate rainfall there. Similar soils are met in the drainage basin of the Colorado River in parts of Colorado. Arizona and California and also in the Rio Grande drainage area in the states of New Mexico and Texas.

In Mexico saline soils are spread out in whole arid region along the West Coast particularly in the states of Sonora, Sinoloa and Durango. Saline soils also occur in the irrigated areas of the Mexicali district, in the Chihuahuan State along the Rio Grande south of El Paso.

7. South America:

Saline soils are in accordance with the high aridity along the Pacific regions of North Chile, Peru and the Southern parts or Ecuador (Fig. 25.1).

8. Somali – Chalbi:

Salt affected soils occupy large areas of Somaliland. The coastal plains are well known for their saline characteristics. The Danakil pan is high in salts. Irrigation of certain soils has led to a salinization because of poor drainage.

9. Iran:

The Dasht-e-kavir is known most widely for its extensive salt crusted soils. Gypsum beds and saline marls underlie these soils. Salty soils also occur along the Person Gulf, the Gulf of Oman and the Arabian Sea. Saline dry lakes are common to Atacama – Loma desert. Borax-lakes are common to Atacama-Loma deserts.