The main objective of this paper is to evaluate the impact of land cover resolution, in comparison with the digital elevation model (DEM) resolution, on hydrological modeling outputs. Three different basins in the various resolutions of DEM (12.5, 25, 50, 100, 500 and 1,000 m) and land-use maps (250, 1,000 and 2,500 m) were collected in this study, and the hydrological modeling process was performed using the Soil and Water Assessment Tool (SWAT) model. The soil type resolution was 1,000 m for all basins, and the runoff modeling was done based on the Soil Conservation Service Curve Number (SCS-CN) method. The final model outputs showed that the DEM cell size variations affect significantly the topographical characteristics of a catchment such as area, mean slope, river network and time to concentration which alter the flood modeling outputs especially in hilly watersheds (mean slope more than 15%) up to 15% for a DEM cell size of 1,000 m in comparison to 12.5 m. Also, the resolution and spatial distribution of land cover maps which directly specify SCS-CN values, can change the output simulated runoff results up to 49% for a land cover cell size of 2,500 m in comparison to 250 m. These results indicated that the quality of the land cover map is more important than the quality of DEM in hydrological modeling. Also, the results showed that for an identical land-use cell size, the differences between model outputs using DEM cell sizes less than 100 m were not very significant. Furthermore, in all models by increasing the DEM cell size, the simulated runoff depth was decreased.

本文的主要目的是评估与数字高程模型分辨率相比，土地覆盖分辨率对水文模型输出的影响。本研究收集了三种不同分辨率的DEM（12.5、25、50、100、500和1,000 m）流域和土地利用图（250、1,000和2,500 m），并使用以下方法进行了水文建模过程土壤和水评估工具（SWAT）模型。所有流域的土壤类型分辨率为1,000 m，并根据土壤保护服务曲线编号（SCS-CN）方法进行了径流模拟。最终的模型输出表明，DEM像元大小的变化会显着影响流域的地形特征，例如面积，平均坡度，河流网络和集中时间改变了洪水模型的输出，特别是在丘陵集水区（平均坡度超过15％）中，DEM单元大小为1.25 m的DEM单元最大为15％。此外，直接指定SCS-CN值的土地覆盖图的分辨率和空间分布，对于2,500 m的土地覆盖单元大小（与250 m相比），可以将输出模拟径流结果最多更改49％。这些结果表明，在水文建模中，土地覆盖图的质量比DEM的质量更为重要。同样，结果表明，对于相同的土地利用单元大小，使用小于100 m的DEM单元的模型输出之间的差异不是很明显。此外，在所有模型中，通过增加DEM像元大小，模拟的径流深度都减小了。