The document discusses different types of irrigation systems that can be used to supply irrigation water. It explains that unskilled groups often use basic dug or driven wells for irrigation, which are prone to contamination and may not work in drought conditions. More advanced drilled wells installed by skilled groups tap deeper underground water sources and are more reliable, as they can still access water during droughts when surface sources have dried up. The document suggests drilled wells as a more effective irrigation solution compared to basic dug wells.