森林流域单元水文模型的构建与应用

目前全球缺水、水污染、洪涝灾害以及水土流失仍然非常严重，尤其在我国北方地区。流域水文模型可用来进行不同需水管理的情景分析，为解决我国水问题提供科学依据。分布式水文模型是流域水文模型的发展方向，具有显著特点：1）应用前景广泛，不仅可以模拟流域水文过程，还可以协助模拟泥沙或污染物的运移过程，为水利工程设计、水土保持、环境保护等领域提供技术支持；2）能够预测流域土地利用或气候变化下的流域水文响应过程变化，为管理部门提供决策支持；3）模型所需要的参数全部具有物理意义，可通过实际测量确定，适合模拟实测系列较短或是无观测流域的水文过程；4）对于目前国际水文界的前沿问题—水文尺度转换提供了一种有效的解决途径。 然而分布式水文模型还不完善，如1)真实性问题。对一些水文过程和边界条件还不确定。2)尺度转换问题。目前很少考虑尺度对参数有效性的影响。3)检验问题。还无法判断对有些难以测量的水文状态变量的模拟正确与否。4)计算时间和数据存储的问题。有些分布式水文模型虽然具有很强的水文物理基础和完善的模型结构，但是计算时间过长和(或)数据存储过大，难以应用。上述问题的核心就是对分布式水文模型的核心—单元水文模型的研究不够，需要为进一步完善单元水文模型进行研究。 本文采用饱和入渗理论、Saint-Venant方程、Richards方程、Penman-Monteith方程等等构建了以有限差分法求解的适用于森林流域的单元水文模型，并通过实验室模拟试验和坡地径流场资料进行了验证，主要结论为： 通过不同坡度和不同雨强下的室内坡面产汇流实验模拟，表明：该模型模拟的坡面流和壤中流过程与实测过程基本一致，峰现时间、径流历时、峰值流量、出流总量模拟值与实测值的相对误差均较小，基本小于10%。模型的模拟精度较高，实用性较强，为深入研究壤中流机制和改进流域降雨-径流模型提供了理论依据。 通过坡地径流观测场实测资料的验证，表明：该模型模拟的坡面流过程精度较高，累计流量的精度更高于小时过程的精度，离差系数、效率系数、确定系数均较理想，具有应用价值，有助于改善分布式水文模型在森林流域的模拟效果。

Such problems as water lack, water pollution, flood disaster and soil erosion are still very severe globally, especially in the northern areas of our country. The watershed hydrological model can be used for scenario analysis of different water-demand management, and provide a scientific basis for solving water problems of our country. The development direction of the watershed hydrological model is the distributed hydrological model, the remarkable characteristics of which show as follows: 1）Broad prospect in application, it not only may simulates watershed hydrological process, but also assistant in simulating transportation process of sediment and pollutant, and provide a technical support for hydraulic engineering design, soil conservation, environmental protection and other fields; 2）Predict the changes of watershed hydrological corresponding process under the condition of watershed land use or climate changes, and provide decision support for management department; 3）All parameters that simulation needed have physical meanings, and determined by practical measurement, suitable for simulating the hydrological process of short measured series or not observed; 4）Provide an effective solving way for such international hydrological front problems as hydrological scale transformation in the present. However, it is necessary to improve the distributed hydrological model, such as follows: 1）Reality problem. Some hydrological process and boundary conditions are not determined. 2）Scale transformation problem. Nowadays, the effectiveness on the scale to parameters is little considered. 3）Test problem. It is unable to estimate that whether the simulation on some difficult measured hydrological state variables is correct or not. 4）Calculation time and data storage. Though some distributed hydrological models have strong hydrological physical basis and perfect model structure, they are difficult to be in practice because of overlong calculation time and (or) excessive data storage. The core of these problems above is that the study of unit hydrology model, the core of the distributed hydrological model, is limited and needs to be improved further. Based on saturated infiltration theory, Saint-Venant equation, Richards equation, Penman-Monteith equation, etc, the present study constructed a unit hydrology model suitable for forest watershed with finite difference method and verified by means of laboratory simulation test and runoff data on slope runoff field. Main results showed as follows: Through rainfall-runoff experiments under different slopes and rain intensities in laboratory,it showed that the processes of simulated surface flow and subsurface flow accorded well with observed ones .The relative errors of runoff peak time,duration,peak rate and gross amount were less than 10%.The model was practicable,and provided theory foundation for improving watershed rainfall-runoff models. Through verification by data of slope runoff field, it showed that the simulated surface runoff had high precision, the gross flow was even more precise,and RRMSE,EF,CD were all rather ideal.The model was applicable,and will help improve the simulation effect of distributed hydrological model in forested watershed.