In response to the intense rainfall event affecting Punjab, Khyber Pakhtunkhwa (KP), and Balochistan, satellite-based rapid flood mapping was conducted to assess the impacted areas on July 11, 2025.
Based on the KDFIMv2 algorithm, the distribution of natural surface water prior to the flooding was derived using multi-source satellite imagery from January to June 2025, including Sentinel-2, Landsat-8, Landsat-9, and Sentinel-1. The surface flood extent on July 11 was detected through the fusion of optical and SAR data acquired on the same day, allowing for timely and accurate identification of flooded areas (Figure 1).
The analysis revealed major flood coverage in the upstream and downstream regions of the Chashma Reservoir, where agricultural lands and rural settlements adjacent to the main river channel were partially submerged. Furthermore, the eastern compartment of the Tarbela Reservoir exhibited significant water surface expansion, inundating wetlands and floodplain areas, with downstream river channels also showing increased surface water coverage.
With forecast rainfall exceeding 50 mm/day over the next three days (Figure 2), there is an elevated risk of additional flooding, particularly in low-lying and already inundated regions. Continued rainfall may aggravate existing flooding around Chashma and Tarbela Reservoirs, and trigger flash floods in nearby agricultural and rural zones.
针对影响旁遮普省（Punjab）、开伯尔-普赫图赫瓦省（Khyber Pakhtunkhwa, KP）和俾路支省（Balochistan）的强降水过程，我们开展了基于卫星遥感的洪水快速制图工作，对2025年7月11日的受灾区域进行了监测与评估。
基于KDFIMv2算法，利用2025年1月至6月的Sentinel-2、Landsat-8、Landsat-9与Sentinel-1多源遥感影像，提取了洪水发生前的自然地表水体分布。通过融合2025年7月11日当天获取的光学与SAR（合成孔径雷达）数据，识别了当日的洪水淹没区域，实现了对洪水影响区的快速精确定位(Figure 1)。
分析结果表明，Chashma水库上下游地区出现了大范围洪水淹没，沿主河道的农田与乡村聚落遭到不同程度水淹。此外，Tarbela水库东部库区水面明显扩张，湿地和泛滥平原被进一步淹没，下游河道的水体覆盖范围也显著增加。
由于未来三天预报降水量持续超过每日50毫米(Figure 2)，该区域面临更高的次生洪水风险，特别是在低洼及此前已受淹区域。持续降水可能加剧Chashma与Tarbela水库周边洪水，并可能在附近的农业区及乡村聚落引发新的突发性洪水。
