Characteristics Related to the Groundwater Around a Saline Plot in Irrigated Areas

土壌の塩類化と地下水の関係を明らかにするために,黄河流域の非塩類化圃場と隣接する塩類化プロットにおいて,表層土の土性と土壌溶液や地下水の水質を調査するとともに,揚水試験を実施して帯水層の水理学的特性値を求めた塩類化プロットでは,非塩類化圃場と比較して,細粒土の割合が多く,Na^+やSO_4^<2->の含有量も多かった.これらはともに,土壌の透水性不良をもたらす要因となる.また,揚水試験の結果より,塩類化プロットでは透水量係数や貯留係数も相対的に小さいものと推定された.これらは間隙が小さく均一で,毛管上昇によって地下水から塩分は供給されやすいが,降雨や灌漑水によるリーチングは起こりにくいことを示唆する.In order to elucidate the relationship between soil salinization and groundwater, soil texture, soil solution and groundwater were examined in a non-saline field and a saline plot next to it in the Yellow River basin. Hydraulic constants of the aquifer also were determined by the pumping-out test. Contents of silt and clay in the surface soil, and contents of Na^+ and SO_4^<2-> in the soil solution were larger in the saline plot than in the non-saline field. These characteristics tend to cause poor drainage. Furthermore, it was supposed by the pumping-out test that both transmissibility coefficient and storage coefficient were small in the saline plot, as compared to the non-saline field. This means that soil pores in the saline plot are smaller and more uniform than those in the non-saline field, and is good for transporting salts upward from the water table by capillary action, but not good for leaching out salts from the soil profile