Facing a severe crisis of thirst, the people receive a miraculous solution through the word of God spoken by Elisha. Despite the complete dryness of their surroundings, they are commanded to take practical steps to prepare the ground for an upcoming miracle [רד״ק]. They are instructed to go into the valley or plain [מצודת ציון, רלב״ג] and dig numerous pits and trenches.
There is a general consensus among commentators that this divine instruction requires them to create extensive excavations throughout the area. These newly dug spaces are meant to serve as water reservoirs for the camp [מלבי״ם, רש״י, מצודת דוד, רד״ק, ביאור שטיינזלץ]. The purpose of this physical labor is to lay the groundwork for an open miracle performed by God. The dry pits will suddenly fill with water without any preceding natural phenomena like wind or rain.
The water that gathers in these reservoirs will be abundant enough to completely satisfy all their needs. It will provide ample hydration for the people, their livestock intended for food, and their riding animals [רלב״ג].