石漠化地区二元水文结构水土-养分流失机制研究

Water and soil loss has always been the focus and hotspot in the rocky desertification treatment, as it is the core issue for development and evolution of rocky desertification. Due to the uniquely binary structure of rocky desertification, water and soil loss presents dual features of ground loss and underground leakage. The mechanism of soil, water and nutrient losses of binary structure in rocky desertification area is not clear so far, while nuclide tracing technique provides a new opportunity for this study. The planned reserch area of this project is the demonstration plot of comprehensive rocky desertification treatment located in Guanling-Zhenfeng of Guizhou. Select different revegetation sample plots of rocky desertification, then use tracing technique of 137Cs, 210Pbex, 7Be and runoff plots. Along with nutrient indicators, apply the approach of combining ground loss with underground leakage. Thus to monitor and analyze the sampled soil profile, water and soil that lose on slope and leak from underground. Thereby, the law will be represented, which is soil nutrients migration and loss features under different revegetation measurements of rocky desertification. Also, loss mechanism of water, soil and nutrient of binary structure in rocky desertification area will be discussed. Apply measurement parameters of soil and water loss to analyze the loss proportion between ground and underground. In adition, a coupling model for soil and water loss of binary structure will be built, so as to provide theories and scientific basis for revealing evolution mechanism of rocky desertification, and for comperhensive treatment of water and soil conservation.

水土流失作为石漠化形成与演化的核心问题，一直是石漠化治理中的关注焦点和研究热点。石漠化地区独特的二元结构造成水土流失具有地表流失与地下漏失的双重特点。但目前对二元结构水土-养分流失机制的认识尚未明确，核素示踪技术为该研究提供了新契机。本项目拟以贵州关岭—贞丰花江石漠化综合治理示范区为研究区，选取石漠化不同植被恢复样地，利用137Cs、210Pbex、7Be示踪技术与径流小区法，结合养分指标，采用地表流失与地下漏失结合的研究思路，对土壤剖面、坡面流失水土以及地下漏失水土进行监测与采样分析，表征石漠化不同植被恢复措施下的土壤养分迁移规律与流失特征，探讨石漠化地区二元结构的水土-养分流失机制。运用水土流失计量参数，分析地表流失与地下流失比例，构建石漠化地区二元结构水土流失耦合模型，为揭示石漠化演化过程机理和探索水土保持综合治理措施提供理论依据。

中国南方喀斯特石漠化是喀斯特水文过程造成土壤侵蚀与生态退化的极端现象，石漠化环境的高度异质性与复杂的二元水文结构，限制了对地表与地下水文过程与产流机制的理解，导致对该区水土-养分流失发生机理认知不足。针对喀斯特石漠化二元水文结构水土-养分流失机制科学问题，在代表中国南方喀斯特石漠化环境总体结构的贵州贞丰-关岭喀斯特高原峡谷区选择顶坛小流域为研究区，发现了石漠化地区不同植被类型对坡面水文过程及其产流产沙的影响、坡面水文过程对养分流失的影响机理；揭示了裂隙水文过程及其影响机理、地下水土漏失机制；突破了石漠化二元水文结构水土流失过程与养分流失机制的认识。降水通过坡面径流方式流失的比例较低(＜10%)，地下渗漏量较高(＞45%)，坡面产流对碳氮流失具有显著影响，撂荒更易造成土壤有机碳流失。揭示了喀斯特石漠化流域水文过程对碳氮流失的影响机制，流域地下渗漏量极大(＞80%)，前期(含水层)水文条件决定流域产流过程，DOC与TSN浓度受初始冲刷效应与稀释效应的交替影响，全年有机碳流失18.43 kg，氮流失13.14 kg。在项目支持下，课题组共发表SCI期刊论文4篇，CSCD期刊论文13篇，博士研究生毕业论文1篇，硕士研究生毕业论文4篇，取得实用新型专利9项，软件著作权5项。研究结果为喀斯特石漠化水土资源优化调控与生态恢复提供科学依据。