Modeling of Watershed Scale Mass Circulation Structure on Nitrogen and Carbon

本研究旨在建立集水区尺度的氮碳质量循环综合模型。由于溶质在流域内的运动在很大程度上受水文径流过程的控制，因此在结合水文径流和水质过程的流域水质模型的基础上建立了质量环流模型。采用DNDC模型对生物代谢的动态过程进行建模。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)流域径流模型和流域水质模型的发展，将Sugawara的水箱模型应用于分流域的水文径流过程。通过在水箱模型中加入水质过程，建立了流域水质模型。该模型对每个子集水区出口的污水负荷排放的输出用于以下分析。(2)流域氮素平衡分析。根据支流走向和地形将流域划分为6个区块。考虑水田、旱田、园林区、居住区等土地利用类型，对各土地利用类型的氮流进行了分析。结合这些土地利用型氮流模型，建立了整个流域的氮平衡模型。(3)流域氮碳物质循环结构模拟。氮和碳的代谢行为采用DNDC（反硝化和分解）模型。DNDC的应用与上述氮平衡模型相同，即通过DNDC模型代替上述每种土地利用类型的氮流模型，建立流域尺度的氮碳质量循环模型。该模型能够正常运行，其质量平衡因子的输出是合理的。因此，模型开发的结果令人满意。利用这些模型预计将有助于实现更好的流域管理。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