ISLAMABAD, Pakistan — Energy-starved Pakistanis, their economy battered by chronic fuel and electricity shortages, may soon have to contend with a new resource crisis: major water shortages, the Pakistani government warned this week. A combination of global climate change and local waste and mismanagement have led to an alarmingly rapid depletion of Pakistan’s water supply, said the minister for water and energy, Khawaja Muhammad Asif. “Under the present situation, in the next six to seven years, Pakistan can be a water-starved country,” Mr. Asif said in an interview, echoing a warning that he first issued at a news conference in Lahore this week. The prospect of a major water crisis in Pakistan, even if several years distant, offers a stark reminder of a growing challenge in other poor and densely populated countries that are vulnerable to global climate change.