基于植被的辽河干流流域沙化修复研究

Basin desertification is caused by natural and human factors, and constrained by the vegetation composition, complex formation mechanism, performances varied. Mostly existing research has been focused on regional theory, there is no systematic regional division of desertification and desertification mechanism and theoretical research for a particular type of repair mechanisms. The main stream basin of Liaohe River, the social economy zone of Liaoning Province, faces the terrible situation of desertification in recent years. So it is urgently needed for the Liaohe river basin to do scientific evaluation and take measures to prevent and control desertification. The research adopts the 3S technology and field survey method, the desertificated basin of Liaohe River main stream is partioned based on the type of vegetation and exogenic forces of erosion. Selecting a typical small watershed in the typical desertificated area, and determine the desertification drive dominant factor with the rough set approach . By performing different configurations of vegetation restoration experiments, analyzing the response of vegetation and the characteristic of vegetation change in sand. Using vegetation - erosion dynamics theory and combined with long time series of basin vegetation change and desertification evolution process, the development trend and the vegetation growth state in sand are forecasted, and the mechanism of vegetation restoration is revealed, and the repair mode and standard of the main stream basin of Liaohe River based on vegetation are established. The aim of the research is to evaluate the current situation, progresses, mechanisms and hazards of desertification in the main stream basin of Liaohe River in large-basin scale, provide theoretical support for interdisciplinary research in the field of desertification and forest hydrology, and provide scientific basis for the decision-making of ecological civilization construction in Liaohe river basin.

流域沙化由自然及人为因素造成，受植被组成制约，形成机制复杂，表现多样。已有成果多为区域性研究，尚无对沙化区域进行系统划分，并针对类型区进行沙化机制及植被修复研究。辽河干流流域是辽宁省社会经济命脉区，近年来沙化形势不断加剧，对其进行修复亟待进行。本研究采用3S技术及实地调查方法，基于植被类型、侵蚀外营力及沙化程度对辽河干流流域沙化土地进行分区；在各沙化类型区选择典型小流域，利用粗糙集方法确定沙化驱动主导因子；进行不同植被配置的修复实验，分析沙区对植被的响应及植被变化特征，利用植被-侵蚀动力学理论结合长时间序列流域植被变化与沙化演变进程，对沙区发展趋势和植被生长状态进行预测，揭示植被修复机理，提出基于植被的辽河干流流域沙化修复模式及标准。有望在大流域尺度评价辽河干流流域沙化现状、进程、机制及危害，为森林水文和荒漠化领域交叉研究提供理论支持，为辽河流域生态文明建设决策提供科学依据。

项目背景：流域沙化由自然及人为因素造成，受植被组成制约，形成机制复杂，表现多样。已有成果尚无对沙化区域进行系统划分，并针对类型区进行沙化机制及植被修复研究。辽河干流流域是辽宁省社会经济命脉区，近年来沙化形势不断加剧，对其进行修复亟待进行。.主要研究内容：研究了辽河干流水沙运移规律及对流域产沙的响应；划定沙化程度，完成沙化分区；确定辽河干流流域沙化驱动主导因子；采用灰色模型进行了沙化趋势预测；建立线性、非线性植被-侵蚀动力关系，揭示流域沙化修复机制；基于137Cs示踪技术探讨了辽河干流沙化在河口湿地的沉积机制；探讨辽河口滨海湿地海岸线变化及对流域产沙的响应机制。.重要结果：河段泥沙主要源于流域产沙；划定沙化分区，绘制了辽河干流流域首张沙化分区图；人口增长是沙化首要因素；未来20年间辽河干流流域沙化土地总面积呈现逐渐减少的趋势；生态修复机制是通过植物作用，提高起动风速、减小风蚀量降低风蚀沙化；通过延长产流时间、减小产沙量、增加土壤抗剪强度降低水蚀沙化；乔灌混栽和人工林是辽河沙化区域最适合的生态修复措施；辽河口湿地潮滩沉积物近50余年平均沉积速率为2.59cm/a；近三十年辽河口湿地总体呈淤积的趋势，来源于上游泥沙。.关键数据：（1）项目区共划定24个沙化分区；（2）自然因素与人为因素对沙化驱动比重分别为48.38%和51.62%。（3）到2033年辽河干流流域沙化土地总面积达3445.74km2，占辽河干流流域总面积10.90%，重度、极重度沙化在未来15年减少40.75%。（4）对比裸地，灌木林林地、乔木林、乔灌混栽林、农田和草地5种生态修复区沙粒起动风速提高了74.82%、46.27%、94.33%、38.15%和75.75%；土壤风蚀量减少了88.1%、87.3%、88.1%、11.5%、81.92%；土壤抗剪强度提高了605.33%、582.67%、658.67%、-9.33%、590.67%。（5）1985-2017年间辽河口湿地海岸线长度减少5.09km，平均淤积速率342.42hm2/a，平均净岸线运动36.76m/a。.科学意义：提出了系统的沙化程度确定方法，确定不同土地利用类型沙化区的阈值及极值，丰富了荒漠化理论；提出的生态修复技术完善了区域治理体系；研究在河流泥砂溯源及河口形成机制等理论方面均提出探索，为完善流域尺度生态修复及泥砂动力理论提供依据。