AGGREGATION OF DISTRIBUTIONS OF INFILTRATION PARAMETERS USING ITS AGGREGATION CRITERIA DERIVED FROM PHILIP'S EQUATION

本研究は水移動に関わる土壌パラメータが分布している場合の領域平均浸透量を算定するに際に, 分布量が集約して扱えるかを明らかにすることが目的である. まず, 水移動に関係する5つの土壌パラメータそれぞれに対するパラメータ平均法の集約化規範を Philip 式に基づいて導いた. この集約化規範は, 土壌パラメータの平均値で表される浸透量集約化指標という新たに提案した指標に対する不等式として, 5つのパラメータ全てについて統一的に表すことができた. この集約化規範を用いて, 同一サイト内で観測された土壌パラメータの分布統計量を用いて, 分布が浸透量算定に与える影響を検討したところ, 飽和透水係数と初期飽和度の集約化は土壌毎に定まる集約化指標と許容誤差, パラメータの変動係数等の集約化条件の両方に大きく依存するが, それ以外のパラメータの変動は小さくあまり影響を与えないことを明らかにした.

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