The basic premise of the Famine Codes formed the basis of numerous subsequent early warning systems. One of the most efficacious is the Turkana District Early Warning System in northern Kenya in which indicators include rainfall levels, market prices of cereals, status of livestock, rangeland conditions and trends, and enrollment on food-for-work projects. The system identifies three levels of crisis: alarm, alert and emergency, each of which is linked to a planned response to mitigate the crisis and try to prevent a worsening of the situation.