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一、董志塬的水文地质条件 董志塬位于甘肃省庆阳地区,是陇东黄土高原中最大的塬,面积828平方公里,有耕地一百万亩以上。 塬面地形总趋势为西北高,东南低。塬面标高1400米左右,塬东、西、南三面为马莲河、蒲河、泾河所切割,相对高差250—300米。沿河出露的塬区地层自下而上为下白垩系K_1砂岩、砂页岩;新第三系N_2棕红色砂质泥岩,厚10—20米;Q_1为浅棕红色午城黄土,厚40米左右;Q_3上部为马蓝黄土,下部为古土壤与粉土质亚砂土互层,共50米左右。 Q_2为塬区的主要含水层,根据1978年5月份所做的带有5个专门观测孔的非稳定抽水试验,用布尔顿、纽曼、雅各布及水位恢复法解释,渗透系数一般在0.3—0.5米/日左右。给水度0.7—0.38。Q_1的粘土层为黄土潜水的隔水底板。
I. Hydrogeological Conditions of Dongzhiyuan Dongzhiyuan is located in Qingyang of Gansu Province. It is the largest plateau in Longdong Loess Plateau with an area of 828 square kilometers and arable land of more than 1 million mu. The general trend of plateau topography is high in the northwest and low in the southeast. Plateau surface elevation of about 1400 meters, the eastern, western and southern sides of the Malian, Puhe, Jinghe cut, the relative elevation of 250-300 meters. Lower reaches of the formation exposed in the river area from bottom to top for the Lower Cretaceous K_1 sandstone and sand shale; Neogene Tertiary N_2 brown red sandy mudstone, thickness 10-20 meters; Q_1 is the light brown red afternoon city loess, thick 40 meters; Q_3 the upper part of horse blue loess, the lower part of the ancient soil and silty sand and sand interbed, a total of 50 meters. Q 2 is the main aquifer in the highland area. Based on the unsteady pumping test with five dedicated observation wells made in May 1978, the Bourdon, Newman, Jacobs and water level recovery methods are used. The permeability coefficient is generally 0.3 -0.5 m / day or so. Water supply 0.7-0.38. The clay layer of Q_1 is a water-retaining floor for loess diving.