Scientific Reports of the Faculty of Agriculture, Okayama University
Published by the Faculty of Agriculture, Okayama University
ONLINE ISSN : 2186-7755


Nagahori, Kinzo
Mitsuno, Tooru
To prove the relation between the increase and decrease of the percolated water quantity in the paddy fields around the lake due to the variation of water level of the lake, we first noticed that not only the physical character of the soil but also the character of soil layers structure were greatly concerned in the phenomena of percolation in the soil under the paddy fields, and in case of thinking of this matter, mentioned the idea of the porcolation water model through down from the paddy fields. Moreover, establishing the simplest two-layer structure model, we examined applicable state of Darcy's law and treatment of the macro model, and verified the propriety of treatment of the percolation water model under consideration of the condition of soil layers. In short, these results are as follows. l) When we considered the macro model, we supposed the imaginary water level H in the case of combining vertical percolation and horizontal direction. In the Fig. 3, as a result of comparing H with h from micro viewpoint, we found that H was nearly equal to the averaged value of h in the vertical direction. 2) When we examined qx in the Fig. 4, we found the following thing. When the value of k2/k1 is smaller than 10, the calculated value is in bad agreement with the measured one. On the other hand, as the value of k2/k1 becomes larger than 10, the calculated is in better agreement with the measured. 3) As we could find in the Fig. 5, it became clear that the calculated value was in fairly good agreement with the measured in the geometic model used here when the value of k2/kl was larger than 10. In the actual paddy fields, the value of L/D is lager. Therefore, it may be thought that the stream of the under layer more approaches to the level stream, and the agreement is further better. 4) By the electric model and approximate calculation, we examined the relation between S2/S1 and q R1/S1 under the condition of k2/k1=20. In consequence, judging from that straight relation between them comes into existence and one is in fairly good agreement with the other as showed in the Fig. 6, it may be thought that the propriety of establishment of macro percolation water model is verified.