Water resources planning and management depend on the quality of climatic data, particularly rainfall data, for reliable hydrological modeling. This can be very problematic in transboundary rivers with limited disclosing of data among the riparian countries. Satellite precipitation products are recognized as a promising source to substitute the ground-based observations in these conditions. This research aims to assess the feasibility of using a satellite-based precipitation product for better hydrological modeling in an ungauged and riparian river in Pakistan, i.e., the Chenab River. A semidistributed hydrological model of The soil and water assessment tool (SWAT) was set up and two renowned satellite precipitation products, i.e., global precipitation mission (GPM) IMERG-F v6 and tropical rainfall measuring mission (TRMM) 3B42 v7, were selected to assess the runoff pattern in Chenab River. The calibration was done from 2001–2006 with two years of a warmup period. The validation (2007–2010) results exhibit higher correlation between observed and simulated discharges at monthly timescale simulations, IMERG-F (R2 = 0.89, NSE = 0.82), 3B42 (R2 = 0.85, NSE = 0.72), rather than daily timescale simulations, IMERG-F (R2 = 0.66, NSE = 0.61), 3B42 (R2 = 0.64, NSE = 0.54). Moreover, the comparison between IMERG-F and 3B42, shows that IMERG-F is superior to 3B42 by indicating higher R2, NSE and lower percent bias (PBIAS) at both monthly and daily timescale. The results are strengthened by Taylor diagram statistics, which represent a higher correlation (R) and less RMS error between observed and simulated values for IMERG-F. IMERG-F has great potential utility in the Chenab River catchment as it outperformed the 3B42 precipitation in this study. However, its poor skill of capturing peaks at daily timescale remains, leaving a room for IMERG-F to improve its algorithm in the upcoming release.

中文翻译：

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跨界河流集水区（巴基斯坦切纳布河）TRMM 和基于 GPM 的降水产品的水文评估

水资源规划和管理依赖于气候数据的质量，尤其是降雨数据，以实现可靠的水文建模。这在跨界河流中可能非常成问题，因为沿河国家之间的数据披露有限。卫星降水产品被认为是在这些条件下替代地面观测的有前途的来源。本研究旨在评估使用基于卫星的降水产品在巴基斯坦一条未经测量的河岸河流（即 Chenab 河）中更好地进行水文建模的可行性。建立了水土评估工具（SWAT）的半分布式水文模型和两个著名的卫星降水产品，即全球降水任务（GPM）IMERG-F v6和热带降雨测量任务（TRMM）3B42 v7，被选中来评估 Chenab 河的径流模式。校准是在 2001-2006 年完成的，有两年的预热期。验证（2007-2010）结果显示，在每月时间尺度模拟、IMERG-F（R2 = 0.89，NSE = 0.82）、3B42（R2 = 0.85，NSE = 0.72）而不是每日时间尺度模拟中观察到的和模拟的排放量之间具有更高的相关性, IMERG-F (R2 = 0.66, NSE = 0.61), 3B42 (R2 = 0.64, NSE = 0.54)。此外，IMERG-F 和 3B42 之间的比较表明 IMERG-F 优于 3B42，这表明 IMERG-F 在每月和每天的时间尺度上都具有更高的 R2、NSE 和更低的偏差百分比 (PBIAS)。结果通过泰勒图统计得到加强，这表示 IMERG-F 的观测值和模拟值之间具有更高的相关性 (R) 和更小的 RMS 误差。IMERG-F 在 Chenab 河流域具有巨大的潜在效用，因为它在本研究中的表现优于 3B42 降水。然而，它在每日时间尺度上捕获峰值的能力仍然很差，这为 IMERG-F 在即将发布的版本中改进其算法留下了空间。