What should a person do if they experience a state of ritual impurity (janabah) while in the desert?

A person in a state of major ritual impurity (junub) should perform tayammum if they cannot find water or if the available water is scarce and insufficient for their essential needs, whether they are in the desert or a city. This is based on the Almighty's saying: "And if you find no water, then perform tayammum with clean earth," and on the Prophet's (peace be upon him) statement to someone who became ritually impure but found no water: "You must use clean earth, for it is sufficient for you."