# Characterization of the 2014 Indus River Flood Using Hydraulic Simulations and Satellite Images
## 1 Introduction  
Flooding is one of the most common environmental hazards, affecting many countries worldwide [1]. Pakistan, like many South Asian countries, is often severely impacted by flooding [2]. The Indus River is the longest river [2] and the most crucial water source in Pakistan, providing water to irrigate the land that produces 90% of the agricultural outputs of the country [3]. This river, however, often bursts its banks during the monsoon season, causing extensive damage to property and crops, as well as loss of lives. Droughts are alsoa recurrent feature in Pakistan, affecting agriculture, livelihoods, and the economy [4]. To better cope with the two extremes of the hydrological cycle, barrages and dams were built along the Indus River to store water during dry periods and to protect against the risk of flooding, respectively [5; 6]. One such barrage is Taunsa Barrage, whose flood attenuation capability has decreased over the years due to severe sedimentation [7].  
Flood mitigation is based on flood risk maps. The drawing of those maps is often based on the outputs of a hydrological model, which requires a digital elevation model (DEM) to represent the topographical surface and define a flood pathway [8]. A DEM can take the form of a digital terrain model (DTM) or a digital surface model (DSM). A DTM is a bare-Earth DEM [9]. Simultaneously, a DSM includes man-made features such as roads and buildings, vegetation, or any other features on the ground that can affect water flow [10]. The latter is particularly important in urban environments where a DSM is preferred for flood studies [11]. Data from various sources are used to develop a DEM, including land surveying, aerial photos, and, more commonly, remote sensing (RS) [9; 10].  
Flood risk mapping has seen the development of new applications over the years, notably the integration of hydrological models with RS in a geographic information system (GIS) [12]. The literature abounds in the use of GIS and RS in flood hazard mapping, for example [13; 14; 15; 16], and more recently on using optical and radar satellite images to validate flood risk maps, for example [8]. Research in GIS and RS has since expanded from what was essentially the delineation of areas at risk of flooding to real-time monitoring of a flood and assessment of its impacts on population and infrastructure [17], and time and cost-effective crop loss assessment after a flood [18], notably for insurance purposes [19].  
In 2014, heavy rains combined with glacier melting triggered flash flooding on the Indus River plains [7; 20]. This was one of the worst river flooding disasters to affect the country, destroying crops, homes, and other infrastructure [21; 22]. Given the Indus River basin exposure to flooding and the devastating impacts that this hazard causes, as well as the likelihood that flooding might increase in the future due to anthropogenic climate change [23], further research is needed to develop flood alleviation measures, including better flood monitoring. In this regard, satellite imagery has become increasingly important, particularly given improvements in image resolution, their processing in GIS, and the availability of 3D technology [24; 25]. This paper presents an approach to map and assess the impacts of the 2014 flood of the Indus River in Pakistan using a hydrological model integrated within GIS and satellite images from Landsat-8. The simulated flood and its impacts are then compared with MODIS images, and recommendations are provided on mitigating future flood risks on the basics of the level of accuracy of the flooding simulations.