What are the Effects of Irrigation on Desert?

Geomorphology:

The physical conditions and geomorphic processes have undergone considerable modification in those deserts and their margins where substantial irrigation has been introduced. As for example, we may keep the Thar Desert and its borders in Rajasthan and Sind in view. Because of the introduction of a vast network of canal, systems such as Bikaner and Rajasthan canal systems and tube-wells or those of the Lower Indus canal systems in Sind remarkable changes have come into being particularly after Independence.

Subordination of Sand on the Surface:

In the copiously irrigated areas, the nature of the surface material has changed. In those areas where sand looked predominant on the surface, because of the sifting and sorting action of water, clay and silt have come up at the surface and sand has gone under.

Reduced deflation:

Because of the presence of water on the surface in artificial water bodies, higher soil moisture and higher watertable deflation is also reduced.

Reduced Wind Erosion:

The wind nearer the ground is not so much armed with sand particles as before the introduction of considerable or large-scale irrigation. As such the erosional processes and effects are also reduced.

Effects on Deposition:

In the irrigated parts of deserts, depositional process is also affected. In arid Deserts the sand dunes, sand ridges, wind-shadows, sand drifts and sand sheets may keep growing changing and migrating. With the introduction of irrigation because of the sifting action of water sand at the surface is subdued as it is mixed up with finer particles and goes under in the company of water. As such, the growth of all the above-noted depositional features may be retarded because of reduced wind-blown sand. This will also affect the morphology, migration and modifications of the depositional features.

Changes in meteorological conditions particularly on microclimatic level are likely to take place with the introduction of irrigation. Humidity will increase. Range of temperature and temperature maxima will be reduced. Convection and eddies may be subdued. Duststorms may also be subdued in force and frequency. All these changes will bear upon the erosional and depositional processes and the desert morphology.

Quite significant effects will come into being through vegetation and land use resulting from irrigation. Irrigation will add moisture to the soil. Generally, the water for irrigation in the desert is imported by means of canals and is not local. Thus, there may be no depletion of ground water reservoir. There will be addition. This will raise water-table and various types of vegetation including trees, bushes and grasses will grow in the erstwhile waste. This will check the force of wind and consequent erosion. It will modify depositional features. It may check the shifting of dunes and other depositional forms. The badlands, which generally occur on the desert margins, will be arrested in growth and deterioration and will be reclaimed.

Irrigation also brings in significant effects on the desert morphology through agricultural activities. Badlands and marginal small dunes may be reclaimed. Ameliorating effects from crop cover follows. Horticulture may also develop and modify the desert processes at least locally.