筑後川

In the rice paddy area in the middle reaches of Chikugo River, we researched the actual condition of water management. The purpose of this study is that it clarifies percolation, lot－management water requirement and delivery water requirement by the water balance analysis and utilizes it for future agricultural water management plan of the object region. The results analyzed are summarized as follows. 1. The average of percolation is 20～30mm/d. When the groundwater level lowers, percolation shows about 40mm/d in the condition of the unsaturated percolation. ln the rainy season, since groundwater level rises, it becomes the saturated percolation, and percolation shows the small value. 2. Lot－management water requirement is greatly different in the every field, and it tends to show large value in the field where set the height of outlet sill low and the field in which intake water is abundant. Like this, Lotmanagement water requirement is different by the water management situation of the field. Then, the proportion of it to intake water is about 15～50%. 3. Delivery water requirement reflects the circumstance of the block and it is different for the every block. The fluctuation of it is intense in the irrigation stage. However, it becomes gentle in the level of the whole district. The proportion of it to the average of intake water in the irrigation stage is about 60%.