Modeling of Watershed Scale Mass Circulation Structure on Nitrogen and Carbon

本研究旨在建立流域尺度下的氮碳综合质量循环模型。由于流域内的溶质运移在很大程度上受水文径流过程的控制，因此在综合了流域径流和水质过程的水质模型的基础上，建立了质量循环模型。采用DNDC模型模拟生物代谢的动态过程。这项研究是在印度尼西亚爪哇岛西部的Cidanau流域进行的。主要研究成果如下：(1)建立了流域径流模型和流域水质模型。通过在Tank模型中加入水质过程，建立了流域水质模型。利用该模型关于各分集水口排污量的输出进行了以下分析。(2)氮…分析分水岭的平衡程度更高。根据支流线形和地形将流域划分为6个区块。考虑水田、旱地、园林林地、居民点等几种土地利用类型，分析了不同土地利用类型的氮素流动。将这些土地利用方式下的氮流模型结合起来，建立了全流域氮素平衡模型。(3)流域氮碳质量循环结构模拟。氮素和碳素的代谢行为采用DNDC(反硝化分解)模型。DNDC模型的应用方式与上述氮素平衡模型相同，即用DNDC模型代替上述各土地利用类型的氮流模型，建立了流域尺度的氮素和碳素物质循环模型。该模型运行良好，质量平衡系数的输出是合理的。因此，模型开发的结果令人满意。预计这些模型的利用将有助于实现更好的流域管理。较少

This study was aimed to establish an integrated nitrogen-carbon mass circulation model for watershed scale. Since solute movement in a watershed is governed largely by hydrological runoff processes, the mass circulation model was developed based on a watershed water quality model combining hydrological runoff and water quality processes. The DNDC model was employed for modeling the dynamic processes of biological metabolism. The study was conducted for the Cidanau watershed in the western part of Java Island, Indonesia. The main results of the study are summarized as follows: (1) Development of watershed runoff model and watershed water quality model Sugawara's Tank Model was applied on sub-catchment basis for the hydrological runoff processes. A watershed water quality model was developed by adding water quality processes to the Tank Model. The model's outputs on effluent load discharges at each sub-catchment's outlet were utilized for the following analysis. (2) Analysis on nitrogen … More balance in the watershed. The watershed was divided into 6 blocks based on tributaries alignment and topography. Considering several categories of land use such as paddy fields, upland fields, garden forest, residential area and so on, nitrogen flow in each land use type was analyzed. The nitrogen balance model for the whole watershed was established by combination of these land use wise nitrogen flow models. (3) Modeling of nitrogen-carbon mass circulation structure in the watershed. The DNDC (DeNitrification and DeComposition) model was employed for metabolic behaviors of nitrogen and carbon. The DNDC was applied in the same manner as the above nitrogen balance model Namely, the watershed scale mass circulation model on Nitrogen and carbon was developed by replacing the above nitrogen flow model for each land use type by the DNDC model. The model could perform properly and its outputs on mass balance factors were considered reasonable. Thus, the result of models development was satisfactory. Utilization of these models is expected to contribute for materializing batter watershed management. Less