Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
Food security
Regionally, Sub-Saharan Africa has the largest number of water-stressed countries of any place on the globe, as of an estimated 800 million people who live in Africa, 300 million live in a water-stressed environment. It is estimated that by 2030, 75 million to 250 million people in Africa will be living in areas of high water stress, which will likely displace anywhere between 24 million and 700 million people as conditions become increasingly unlivable. Because the majority of Africa remains dependent on an agricultural lifestyle and 80 to 90 percent of all families in rural Africa rely upon producing their own food, water scarcity translates to a loss of food security.