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<p>A gigantic project named Gully Land Consolidation (GLC) was launched in the hillgully region of the Chinese Loess Plateau in 2011 to cope with land degradation and create new farmlands for cultivation. The dynamic change of groundwater table and loess subsidence in the backfilled farmland are the main causes of site disasters and soil disease, but there is a lack of research on these issues. Based on this, the Shijiagou (SJG) backfilled farmland which is a typical GLC engineering site located in Ansai District, Yan’an City, Shaanxi Province was selected as the study area in this paper. Field site monitoring was carried out in this area, including four aspects of monitoring: rainfall, groundwater table, soil moisture and soil settlement displacement. The following findings were obtained from the analysis of the monitoring data in 2019–2020: (1) The backfilled farmlands have suffered a significant groundwater table rise. And the percentage increase of groundwater table increased from the upstream of F-1 (such as 49.2%, 46.3%, 26.4%) to the downstream of F-5 (90.0%, 52.3%, 34.2% correspondingly), which is related to the terrain of the valley channel and dam seepage. It is also revealed that rainfall characteristics are positively correlated with the depth of water infiltration and groundwater table. (2) The influence depth of rainfall infiltration on soil moisture of the backfilled loess in the GLC study area is no more than 2.5 m, and that within 1.5 m depth is significantly affected by rainfall. In addition, the dramatic rise in the groundwater table led to a steep increase in soil moisture, thus the soil underwent collapse deformation due to water immersion, and the farmland experienced large subsidence displacement. (3) The backfilled loess of the GLC farmland was in a continuous consolidation and settlement stage after the filling completion. With the passage of time, the settlement displacement and settlement rate of the backfilled loess gradually decreased, from 1.0–1.9 mm/d in 2019 to 0.4–0.8 mm/d in 2020, which indicates the GLC farmland tended to be stable. This study reveals the hydrological evolution characteristics and settlement deformation laws of the backfilled loess, which is important for the stability of the farmland and the management of the GLC project.</p>

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Hydrologic Characteristics and Settlement Deformation of Backfilled Loess in Yan’an, China

  • 期刊论文

  • 发表日期：

    2025年3月3日

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  • Lina Ma,
  • Shengwen Qi,
  • Songfeng Guo

摘要

A gigantic project named Gully Land Consolidation (GLC) was launched in the hillgully region of the Chinese Loess Plateau in 2011 to cope with land degradation and create new farmlands for cultivation. The dynamic change of groundwater table and loess subsidence in the backfilled farmland are the main causes of site disasters and soil disease, but there is a lack of research on these issues. Based on this, the Shijiagou (SJG) backfilled farmland which is a typical GLC engineering site located in Ansai District, Yan’an City, Shaanxi Province was selected as the study area in this paper. Field site monitoring was carried out in this area, including four aspects of monitoring: rainfall, groundwater table, soil moisture and soil settlement displacement. The following findings were obtained from the analysis of the monitoring data in 2019–2020: (1) The backfilled farmlands have suffered a significant groundwater table rise. And the percentage increase of groundwater table increased from the upstream of F-1 (such as 49.2%, 46.3%, 26.4%) to the downstream of F-5 (90.0%, 52.3%, 34.2% correspondingly), which is related to the terrain of the valley channel and dam seepage. It is also revealed that rainfall characteristics are positively correlated with the depth of water infiltration and groundwater table. (2) The influence depth of rainfall infiltration on soil moisture of the backfilled loess in the GLC study area is no more than 2.5 m, and that within 1.5 m depth is significantly affected by rainfall. In addition, the dramatic rise in the groundwater table led to a steep increase in soil moisture, thus the soil underwent collapse deformation due to water immersion, and the farmland experienced large subsidence displacement. (3) The backfilled loess of the GLC farmland was in a continuous consolidation and settlement stage after the filling completion. With the passage of time, the settlement displacement and settlement rate of the backfilled loess gradually decreased, from 1.0–1.9 mm/d in 2019 to 0.4–0.8 mm/d in 2020, which indicates the GLC farmland tended to be stable. This study reveals the hydrological evolution characteristics and settlement deformation laws of the backfilled loess, which is important for the stability of the farmland and the management of the GLC project.