The proper planning of storage structures, waterways, irrigation schemes, water harvesting, erosion control structures, and groundwater development strategies requires accurate estimation of surface runoff. However, hydrologists in Saudi Arabia face serious challenges, specifically due to the rare availability of surface runoff data. In this study, the soil conservation service-curve number (SCS-CN) method integrated with geographic information system (GIS) and remote sensing (RS) was utilized to estimate the surface runoff in Wadi-Uranah basin, in the western region of Saudi Arabia. Different thematic maps such as slope, hydrologic soil group (HSG), land use/land cover (LULC), and daily rainfall have been created in GIS environment and processed to generate the curve number (CN) and surface runoff maps. Based on the soil classification results, the study area was categorized into two HSGs (B and C). The dominant HSG was group C, representing about 98.8% of the total area. The LULC analysis showed four main land use types in the study region: urban, rocks, barren soil, and agricultural areas. Furthermore, the finding results showed that CN values for the normal conditions (CNII) ranged between 74 and 93 in agricultural and both urban and rock areas, respectively. The CNII values were further corrected using slope data to derive slope-adjusted CNII. Moreover, the rainfall-runoff results showed an increase in the daily runoff of the study region with a minimum of 15 mm to a maximum of 74 mm. Another interesting result was rainfall-runoff linear regression analysis that showed a good correlation of 0.98. Additionally, the peak runoff hydrograph flows for 10-, 50-, and 100-year return periods obtained from the SCS-based dimensionless unit hydrograph were 828, 1353, and 1603 m3/s, respectively. Therefore, this study highlights that the SCS-CN method integrated with RS and GIS deserves further attention for estimating runoff of ungauged basins for better basins management and conservation purposes.

中文翻译：

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使用基于 RS 和基于 GIS 的 SCS-CN 方法估算半干旱地区地表水径流

蓄水结构、水道、灌溉计划、集水、侵蚀控制结构和地下水开发策略的正确规划需要准确估计地表径流。然而，沙特阿拉伯的水文学家面临着严峻的挑战，特别是由于地表径流数据很少可用。在这项研究中，结合地理信息系统（GIS）和遥感（RS）的土壤保持服务曲线数（SCS-CN）方法被用来估计沙特西部地区瓦迪-乌拉纳盆地的地表径流。阿拉伯。在 GIS 环境中创建了坡度、水文土壤群 (HSG)、土地利用/土地覆盖 (LULC) 和日降雨量等不同专题图，并对其进行处理以生成曲线数 (CN) 和地表径流图。根据土壤分类结果，研究区域被分为两个 HSG（B 和 C）。占主导地位的 HSG 是 C 组，约占总面积的 98.8%。LULC 分析显示了研究区域的四种主要土地利用类型：城市、岩石、贫瘠土壤和农业区。此外，研究结果表明，正常条件下的 CN 值 (CNII) 在农业、城市和岩石区分别介于 74 和 93 之间。使用斜率数据进一步校正 CNII 值以获得斜率调整后的 CNII。此外，降雨径流结果显示研究区域的日径流从最小 15 毫米增加到最大 74 毫米。另一个有趣的结果是降雨-径流线性回归分析，显示了 0.98 的良好相关性。此外，峰值径流水位线流量为 10-、50-、从基于 SCS 的无量纲单位水文过程线获得的 100 年重现期分别为 828、1353 和 1603 m3/s。因此，本研究强调，结合 RS 和 GIS 的 SCS-CN 方法值得进一步关注，以估算未测量流域的径流，以实现更好的流域管理和保护目的。