The Long Shaoling Highland Loess Aquifer Conditions And Controlling Factors

The modern soils moisture in the loess plateau has been studied a lot, but there are less research on the soil water reason property and the water bearing space of loess, and developing this work has very important sineice and actual significance to reveal loess strata penetuability, water bearing space and water bearing vertical change rules.In order to get better results, we do the seeping experiment and sampling research in L₁-S₅ section of Shaoling tableland. Than the moisture content, porosity determination grain size and CaCO₃ are measured well, and combined with seeping experiment the characteristics and reasons of water bearing layers and aquifuge have been discussed, which provide basis for exploiting and utilizating groundwater and find out loess groundwater resources distribution rules.By the experiment measuring, calculating, and theory analysing , we get the conclusions as bellow:(1) 10 groups of experiments have been done in different layers of Shaoling plateau, every group were repeated twice to four times and we choosed 20 groups of datas with good reproducibility to analyse. Comparing seeping speed of each layer of loess and red paleosol, the seeping speed of loess is higher than that of red soin in the same layer. The seeping seed of 5 layers of loess usually get lower with the increasing depth. Only the permeability of L4 is abnormal and the seeping seed of L4 is higher than that of L3, which becauses of many fractures in L4. And the permeability of L4 is the smallest in the 5 layers of red paleosol, which is 0.14. By the seeping experiment datas fitting with Koctakob formula, Horton formula and experience formula, we can get the infiltration curve of L₁,S₁,L₂,S₃,S₄,L₅,S₅ fitting best with Koctakob formula among the fitted three kinds of formulas, whose correlation coefficients is between 0.9739 to 0.9958. The infiltration curve of S₂,L₃,L₄ fitted best with experience formula, whose correlation coefficients is between 0.9522 to 0.9787.(2) The average porosity of the first to fifth loess layer is 50.42% and the first to fifth paleosol layer is 43.67% in studied section, and their quantitative difference is 6.74%. Loess layer with comparatively rough granularity, comparatively big porosity, loose and porous formed easily water-bearing layer. Paleosol layer with rather fine granularity, comparatively small porosity and weak permeability, formed easily water-resisting layer.(3) Gravity water is difficult to go through CaCO3 nodules horizon under the paleosol with compact structure. So CaCO3 nodules horizon also formed easily water-resisting layer.(4) Loess layer with strong permeability and water bearing space developing well are attributed to cold -dry climate and rather weak pedogenesis. And red brown paleosol with very weak permeability are attributed to moist climate and rather strong pedogenes.(5) By compaired seeping experiment data in loess section of Changwu with that in Shaoling tableland of Chang'an, we can get penetrability of loess in Shaoling tableland is smaller than that in Changwu, which is attributed to Changwu in northwest of Shaanxi, more cold and dry than Shaoling tableland and weaker pedogenesis.