Permeability and Groundwater Enrichment Characteristics of the Loess-Paleosol Sequence in the Southern Chinese Loess Plateau

Tianjie Shao,Dianxing Song,Ruojin Wang,Jingbo Zhao,Peiru Wei,Junjie Niu,Zhiping Xu

doi:10.3390/w12030870

Abstract

To determine the permeability characteristics and the groundwater enrichment conditions of loess and paleosol layers, this article systematically investigated the permeability, magnetic susceptibility, porosity, and carbonate mass percentage of representative loess-paleosol layers (L1 to S5) on the Bailu tableland in the Chinese Loess Plateau south. The result of in situ permeability measurements showed that the average time to reach quasi-steady infiltration of loess layers is shorter than that of paleosol layers. In addition, loess layers have higher porosity and better water storage spaces than paleosol layers and were prone to form aquifers. Paleosol layers, on the contrary, are more likely to form aquitards. The difference between loess and paleosol in permeability, porosity and groundwater enrichment conditions is largely attributed to lower intensity pedogenesis of loess, which is in turn ascribed to the colder and drier palaeoclimatic conditions. It is worth mentioning that the CaCO3 concretion layer is a good aquifuge for its compact structure. Generally, the empirical formula of the Koctakob formula is applicable for describing the permeability rule of loess and paleosol layers, and the parameters of the empirical formulas can provide an important reference for hydrological and agricultural departments. In this regard, the Quaternary climatic change theory can contribute to the hydrogeology of the Chinese Loess Plateau, and the regional climatostratigraphy can be regarded as a baseline for local water resource positioning and revegetation in such a semi-arid area, which broadens the application field of Quaternary climatic change theory. Meanwhile, it also provides a reference path for solving water shortages of other loess distribution areas in China and other countries.

Highlights

Since the 1980s, numerous important achievements have been established through research on the source of loess holard and groundwater, the characteristic of water permeability, and migration [1,2,3]. we understand that atmospheric precipitation is the main source of loess groundwater, with the occurrence type being hole-fissure water and pore water [4]
The mean infiltration rate of L2 before quasi-steady status was 4.12 mm/min, whereas its quasi-steady infiltration rate was 2.33 mm/min (Figure 2a), both of which were largest in all loess/paleosol layers
When the climate is dry and little rain, the soil moisture mainly exists in the paleosol layers with fine particles, dense texture, and low porosity

Summary

Introduction

Since the 1980s, numerous important achievements have been established through research on the source of loess holard and groundwater, the characteristic of water permeability, and migration [1,2,3]. we understand that atmospheric precipitation is the main source of loess groundwater, with the occurrence type being hole-fissure water and pore water [4]. This research determined water sources, migration and occurrence space in the loess aeration zone to some extent, but there have been few studies on the specific layer and laws of multilayer loess groundwater gathering in the vadose zone, the types of aquifers and aquitards, the relation between loess water storage spaces and palaeoclimate change. Researchers studied loess and its groundwater, regarding loess as sediments [5], but they did not realize that loess is a kind of soil, which has great significance for uncovering the migration characteristic, gathering laws, and occurrence types of loess holard and groundwater. The loess has undergone the effect of pedogenesis after the Aeolian deposits It has the characteristics of soil, such as being porous and fertile, and can grow vegetation, etc. Hu [6] and Bloemendal [7] hold similar views

Methods

Results

Conclusion