UAV-Based Flood Mapping and Damage Assessment in Harnai Khawar, Swat, Khyber Pakhtunkhwa, Pakistan

Iqra Hameed; Rabia Qadir; Amir Ali; Muhammad Sohail; Saif Ullah Akhter

Authors

Iqra Hameed Institute of Space Science, University of the Punjab, Lahore
Rabia Qadir Institute of Space Science, University of the Punjab, Lahore
Amir Ali Institute of Space Science, University of the Punjab, Lahore
Muhammad Sohail Department of Geography, Government Graduate College of Science, Wahdat Road, Lahore
Saif Ullah Akhter Department of Geography, Government Associate College, Eminabad, Gujranwala

Keywords:

Flood Assessment, UAV Imagery, Swat Basin, Aerial Photogrammetry, GNSS, GIS, Disaster Management

Abstract

Floods is among the most destructive hydrological hazards in Pakistan, particularly across the steep, data‑sparse basins of Khyber Pakhtunkhwa (KPK). The 2022 monsoon produced catastrophic damage in the Swat Valley, disrupting transport, irrigation, and housing. This article demonstrates an Unmanned Aerial Vehicle (UAV) workflow for rapid, high‑resolution flood mapping, damage quantification, and risk zonation in the Barwai Khwar sub‑watershed of the Swat River Basin. Pre‑event context was assembled from Google Earth Pro imagery (12 June 2022), and post‑event aerial surveys were flown using a DJI Phantom 4 Pro (v2.0) with GNSS‑supported Ground Control Points (GCPs). Imagery was processed in Agi soft Meta shape to generate Ortho mosaics and surface products, then analyzed in a GIS to delineate inundation, channel widening, structural damage, and agricultural losses. The floodplain width locally expanded from approximately 7 m to 76 m; damaged linear infrastructure includes ~2.18 km of retaining walls and 39 m of bridges. Surface impacts include ~6,271 m² of residential area and ~22.56 ha of cropland affected. The approach provided near‑centimeter spatial detail, enabling precise polygonal accounting for recovery planning and identification of high‑risk margins where unprotected construction coincides with steep banks and tight meanders. Findings confirm the value of UAV photogrammetry as a fast, replicable, and cost‑effective complement to satellite‑based disaster assessment in Pakistan’s mountain valleys, supporting preparedness, reconstruction, and resilient land‑use decisions.

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