Assertion: The introduction of canal irrigation in Rajasthan has influenced the environmental conditions of the region both positively as well as negatively.
Reasoning: The intensive irrigation and excessive use of water have led to the emergence of twin environmental problems of afforestation and pasture development.

Assertion (A) is correct, but Reasoning (R) is incorrect.

The introduction of canal irrigation in this dry land (Rajasthan) has transformed its ecology, economy and society. It has influenced the environmental conditions of the region both positively as well as negatively. The availability of soil moisture for a longer period of time and various afforestation and pasture development programmes under CAD have resulted in greening the land. This has also helped in reducing wind erosion and siltation of canal systems. But the intensive irrigation and excessive use of water have led to the emergence of twin environmental problems of waterlogging and soil salinity.