To facilitate orderly and efficient irrigation, areas of around 150 hectares are designated as irrigation units called "water resource groups." Each of these in turn is split into three smaller irrigation zones with their own "water workers" to control the flows and amounts of water.
小兵立大功徒有硬體還不夠，為了有秩序和效率的灌溉，各區域又以約一百五十公頃為一個灌溉單元，稱為水利小組，每小組下再設三個小區輪流灌溉，並由「掌水工」來管控水量。