黄土坡地土壤养分随地表径流流失动力机制与模拟模型

Serious water and soil losses not only cause amount of nutrient loss in soils and soil quality degradation, but also lead to water body pollution. Therefore, water, soil and nutrient loss involves in the agriculture production and the water circumstance protection. In the project, according to the exiting scientific problems in the studies on water, soil and nutrient loss on slope land, the dynamic processes of water, soil and nutrient transports over slope land are considered as the main research objects. The approaches of experimental studies and mathematical simulations will be adopted to study the effects of rainfall features, slope feature, planting structures and other regulating methods on water, soil and nutrient loss processes over slope land based on the dynamic theories of nutrient transport in soils. Features of water, soil and nutrient losses on loess slope and acting mechanisms of several of regulation methods will be comprehensively analyzed, and the comprehensive indicators describing water, soil and nutrient loss over loess slope land will be established. The conceptual models describing water, soil and nutrient loss processes during rainfall, the dynamic models describing the dynamical processes of water, soil and nutrient transport over loess slope land and the comprehensive models for the water, soil and nutrient loss during a certain time interval will also be established. The study results will enrich the theory of matter transport over slope land and provide the scientific theories and methods for optimizing regulating methods and predicting the loss amount of water, soil and nutrients on slope land. The research results will be published in journals at home and abroad, and 30 relevant papers will be published in journals and the 15 papers will be published in the journals collected by SCI citation index groups.

严重的水土流失造成土壤中大量养分流失和土壤质量下降，导致水环境面污染,因此，坡地水土养分流失不仅是一个农业问题，也是一个水环境问题。本项目针对水土养分流失研究中存在的科学问题，以降雨条件下坡地水土养分迁移动力过程为研究对象，以坡地土壤养分传输动力学理论为基础，以试验研究与数学模拟为手段，通过系统研究降雨特征、坡面特征、土壤特征、种植结构、其他调控措施等对水土养分流失特征的影响，揭示黄土坡地水土养分流失机制及各种控制措施作用机理，提出描述坡地水土养分流失特征综合动力学指标，建立描述次降雨或时段降雨下坡地养分流失的概念模型和水土养分传输动力过程的动力学模型，以及描述一定时段内水土养分流失的综合模型，丰富坡地物质迁移的动力学理论，为优化控制措施和预测坡地水土养分流失提供科学理论与方法。研究成果将在国内外学术期刊发表，发表学术论文30篇，其中SCI收录论文15篇。

水土流失是一个世界性问题，严重的水土流失不仅使土壤中氮、磷、钾等养分大量流失，导致土壤肥力减退，土壤质量下降，而且造成水环境农业面源污染。因此，开展坡地水土养分流失研究具有重要理论价值和现实意义。采取室内外试验研究、理论分析和数学模型相结合方法，系统研究了不同条件下黄土坡地水土养分流失及其动力特征，明确了降雨特性（降雨强度、雨滴动能、雨型）、土壤特征（土壤质地、土壤容重、土壤构造、土壤含水量、底面透水性）、坡面特性（坡度、坡长、坡型）、（植物类型、种植密度、生长特征）等因素对坡地水土养分流失影响，阐明了施加化学改良剂（剂施加PAM、纳米碳、羧甲基纤维素钠）、地面覆盖（枯枝落叶覆盖、秸秆覆盖、碎石覆盖、碎石与植被组合覆盖）、植物生长（植物类型、种植密度、生长特征）等控制坡地水土养分流失功效，明确了坡地物质传输动力特征。研究发现自然植被所形成枯枝落叶覆盖物严重影响坡地水土养分迁移过程，在一般雨强条件下，基本不形成地表径流和发生水土养分流失，这可能是黄河泥沙减少的重要原因之一。同时也发现碎石覆盖不仅减少坡地水土养分流失的数量，而且增加了土壤入渗能力，并土壤入渗能力随碎石覆盖度增加而增加，为黄土坡地降水资源化提供新的理论依据和途径。依据黄土坡地降雨入渗产流特征，建立了具有明确物理意义的产流数学模型、上方来水条件下土壤侵蚀模型、基于混合深度的土壤养分向地表径流传递数学模型，创建了基于降雨和水流分散能力的土壤养分向地表径流传递数学模型、考虑雨型影响坡地水土养分传输数学模型，以及主要参数确定方法。利用国内外相关研究资料，构建了预测次降雨坡地养分流失量数学模型。同时也揭示了植被过滤带调控水土养分流失机制，分析了其作用效果，并构建了相应数学模型，为预测分析坡地水土养分流失和优化坡地控制措施提供了理论依据和有效方法。