岩溶区湿地垦殖对土壤-表层岩溶带孔/裂隙水流动的影响

With the development of binary structure, the ecosystem of Karst wetland is fragile, and the laws of pore/fissure water flow of soil-epikarst zone under wetland reclamation are significantly different from that of other regions. However, the driving mechanisms of the pore/fissure water flow of soil-epikarst zone under wetland reclamation were not entirely clear. The proposed project will consider the soil-epikarst zone under wetland reclamation. Based on field monitoring with transect distributed points and periodic sampling in study areas, this project aims to characterize the effects of wetland reclamation on the surface/fissure soil hydraulic characteristics. With a series of field simulated rainfall experiments, the relationships between wetland reclamation, soil hydraulic characteristics, the structure of soil-epikarst zone and soil moisture dynamics were obtained, and the effects of wetland reclamation on the pore/fissure water flow of soil-epikarst zone was clearly detected. Finally, based on the simulation analysis, the project is expected to clearly detect the influence mechanisms of land use changes and “returning farmland to wetland” on pore/fissure water flow for Karst wetland. The research results will enrich and develop the response and adaptation theory for sensitive ecosystem, and provide scientific basis for the ecological recovery in the Karst region of Southwest China.

岩溶湿地生态系统脆弱，二元结构发育，在湿地垦殖作用下，土壤-表层岩溶带的孔/裂隙水流动规律与其它地区明显不同，但现阶段对湿地垦殖下的土壤-表层岩溶带孔/裂隙水流动相关驱动机制还缺乏充分认知。本项目以湿地垦殖下的土壤-表层岩溶带为研究对象，通过布设样带和周期性取样，确定岩溶区湿地垦殖对表层/裂隙土壤水力特性的影响；通过野外模拟降雨响应试验，建立湿地垦殖、土壤水力特性、土壤-表层岩溶带结构与表层/裂隙土壤水分动态的关系，阐明湿地垦殖对土壤孔隙水流和表层岩溶带裂隙潜流的影响；数值模拟分析岩溶湿地土地利用变化和退田还湿对土壤-表层岩溶带孔/裂隙水流动的影响机制。研究成果可丰富和发展敏感生态系统响应与适应理论体系，为西南岩溶区退化生态系统的恢复重建提供科学依据。

喀斯特地下结构复杂，湿地垦殖后土壤-表层岩溶带的孔/裂隙水流动规律与其它地区明显不同，但现阶段对土壤-表层岩溶带孔/裂隙水流动相关驱动机制还缺乏充分认知。本项目以湿地垦殖后的土壤-表层岩溶带为研究对象，通过布设样带和周期性分层取样，结合开挖剖面染色示踪试验，确定了岩溶区湿地垦殖对表层/裂隙土壤水力特性的影响；通过模拟裂隙土柱入渗试验和模拟土壤-表层岩溶带长序列水文监测，建立了土壤水力特性、土壤-表层岩溶带结构与表层/裂隙土壤水分动态的关系，阐明了湿地垦殖后土壤孔隙水流和表层岩溶带裂隙潜流规律；通过Python平台，开发了2个土壤-表层岩溶带孔/裂隙水流动小尺度预测模型OpenKarHydro和CoreKarHydro。项目取得了以下重要结果：1）人为踩踏活动增强了土壤优先流强度，人为踩踏干扰程度下土壤的大孔隙平均水流贡献率均超过95%，喀斯特土壤水分入渗以大孔隙为主要入渗通道，碳酸盐岩红土导水性能主要受土壤大孔隙对水流的作用控制(>70%)；2）高碎石含量对碳酸盐岩红土水分入渗具有显著抑制作用，通过改进的Green-Ampt模型反演得出含碎石夹层土壤持水性随碎石含量增加而增强；3）裂隙填充物和构型对碳酸盐岩红土水力性质有显著影响，仅占土体体积0.5%的裂隙能够使土壤的导水性能提高19.2-94.0%；4）基于Laio公式的OpenKarHydro模型能在大多数情况下有效预测土壤-表层岩溶带孔/裂隙水流动，基于理查德方程的CoreKarHydro模型能精确预测土壤-表层岩溶带孔/裂隙水流动（RMSE<0.15, R2>0.6)。在该项目的支持下，已发表基金标注学术论文7篇，其中SCI一区论文2篇(一作)、SCI二区论文1篇（一作），通讯作者一级学报论文5篇（包括1篇录用待刊论文），参加国内学术会议3次（作分组报告2次），培养硕士研究生6名。研究成果可丰富和发展敏感生态系统响应与适应理论体系，为西南岩溶区退化生态系统的恢复重建提供科学依据。