What geographical feature primarily differentiates the water reliance of the irrigated Indus Plain from the arid Western Highlands?

💡 Explanation:

The arid nature and low water availability in Pakistan's Western Highlands (including large parts of Balochistan and western Khyber Pakhtunkhwa) are primarily a consequence of the rain shadow created by the Sulaiman and Hindu Kush ranges. These mountains block moisture-bearing winds, leading to significantly lower annual precipitation compared to the areas influenced by the monsoon and the extensive, glacier-fed Indus River System in the eastern Indus Plain (Punjab and Sindh). This forces the Western Highlands to rely on different, often non-perennial, water management techniques.