Simulation of Dam-Break Flood Wave and Inundation Mapping: A Case study of Attabad Lake

The break study of Landslide or embankment dams is more essential due to uncertainty in their composition and lack of knowledge of their response to other natural events because they are natural and not properly designed for any disaster. The paper aims to improve different methods of hydraulic modeling of dam break. In this present study dam break of Attabad lake is simulated using the computational fluid dynamics technique. The numerical model (FLOW-3D) is developed to solve the Reynolds averaged Navier-Stoke equation fully in 3D to predict peak flow depth at different cross-sections, peak velocity, peak discharge, time to peak depth, and time to peak discharge. The standard RNGturbulence model is employed to simulate turbulence and then flood inundation maps and velocity vectors for flow at villages are drawn. The results show that most of the flood wave modeled through the Hunza river channel, is contained by the flood plain of Hunza River but for some of the villages i.e. Miaun and chalat, which are situated inside the flood plain of Hunza River are at higher risk of inundation but the flood arrival time estimated for these villages is 31 and 44 min respectively which is enough time for the evacuation of the population to safer areas while for some villages like Hassan Abad situated adjacent to Ali Abad is at higher risk of inundation while the estimated flood arrival time for the village is 12 min which are not enough for the evacuation of the population hence will need some extra flood protection structures for flood containment. The estimate of the peak velocities implies higher shear stress in the river plain, risk of heavy erosion, damage to agricultural lands, residencies, and morphological changes are projected. The analysis of the dam break i.e. Peak depths, Peak Velocities, flood arrival time, and flood inundation maps should only be used as a guide in future risk analysis and flood management.

Status of Major Glaciers of Hunza River Basin, Under Changing Climatic Conditions of Pakistan Over the Period of (1990-2018)

Ice masses and snow of Hunza River Basin (HRB) are an important primary source of fresh water and lifeline for downstream inhabitants. Changing climatic conditions seriously put an impact on these available ice and snow masses. These glaciers may affect downstream population by glacial lake outburst floods (GLOF) and surge events due to climatic variation. So, monitoring of these glaciers and available ice masses are important. This research delivers an approach for selected glaciers of the Hunza river basin. An attempt is made in this study using Landsat (OLI, ETM, ETM+, TM), digital elevation model (DEM), Geographic Information System and Remote Sensing techniques (RS&GIS) techniques. We delineated 27 glaciers within HRB from the period of 1990-2018. These glaciers' total area is about 2589.75 ±86km 2 in 1990 and about 2565.12 ±68km 2 in 2018. Our results revealed that from 2009 to 2015, glacier coverage of HRB advanced with a mean annual advance rate of 2.22±0.1 km 2 a -1 . Conversely, from 1994 to 1999, the strongest reduction in glacier area with a mean rate of - 3.126±0.3km 2 a -1 is recorded. The glaciers of HRB are relatively stable compared to Hindukush, Himalayan and Tibetan Plateau (TP) region of the world. The steep slope glacier's retreat rate is more than that of gentle slope glaciers, and the glaciers below elevation of 5000 m above sea level change significantly. Based on climate data from 1995-2018, HRB shows a decreasing trend in temperature and increasing precipitation. The glacier area's overall retreat is due to an increase in summer temperature while the glacier advancement is induced possibly by winter and autumn precipitation.

Mapping Fluctuations of Hispar Glacier, Karakoram, using Normalized Difference Snow Index (NDSI) and Normalized Difference Principal Component Snow Index (NDSPCSI)

Investigation of the fluctuations in the snow-covered area of the major glaciers of the Karakoram range is essential for proper water resource management in Pakistan, since its glaciers are responding differently to the rising temperatures. The objective of this paper is to map snow covered area of Hispar glacier in Hunza river basin for the years 1990, 2010 and 2018. Two techniques, (NDPCSI) Normalized Difference Principal Component Snow Index and (NDSI) Normalized Difference Snow Index were used. Hispar glacier of the Hunza basin has lost 114 km2 of its ice cover area, during the last 28 years, with an alarming annual retreat rate of 1.67 km2 of glacier ice from 1990 to 2018. Hunza basin experienced a +1°C rise in both mean minimum and mean maximum temperature during 2007 to 2018.as a result, Karakorum ice reserves have been affected by rising temperature of the region. Due to temperature rise, retreat of snowcovered area of Hispar, Karakoram mountain range shows a shift in the cryospheric hazard zone.

Glacier-Related Hazards Along the International Karakoram Highway: Status and Future Perspectives

The China–Pakistan international Karakoram Highway passes through the core area of the “Karakoram Anomaly,” whose glaciers have maintained or increased their mass during a period when most glaciers worldwide have receded. We synthesized the literature and used remote-sensing techniques to review the types, distribution, characteristics, causes and frequency of major glacial hazards along the Karakoram Highway. We found that the glacier-related hazards could be divided into direct and indirect hazards, including glacier surges, glacial lake outburst floods, and glacial floods, which are concentrated in East Pamir and the Hunza River Basin. In the past 100 years, hazards from glaciers surges and glacial floods only occurred once and twice, respectively, which appear suddenly, with the hazard-causing process being short-lived and occurring mainly in the summer. Glacial lake outburst floods mainly occur in the spring and summer in the Hunza River Basin. Among these, ice-dammed lakes have the highest frequency of flooding, their formation and outbursts being closely related to the sudden advancement of surge-type glaciers. Under the background of global climate warming, we speculate that the glacier surge cycle may shorten and the frequency of the formation and outbursts in the glacial lakes may increase. In the future, we should combine models and new field observations to simulate, and deepen our understanding of the physical mechanisms of different glacier-related hazards. In particular, on-site monitoring should be carried out, to include the evolution of glaciers subglacial hydrological systems, the thermal state at the base of the glaciers, and the opening and closing of drainage channels at the base of the ice dams.

Geospatial Analysis and Simulation of Glacial Avalanche Hazard in Hunza River Basin

Glacial avalanche hazard poses threat to human lives and damage settlements / infrastructures in alpine glaciers mountainous regions. A gigantic ice plus rock avalanche destroyed Gyari military camp in Siachen sector on April 2012 and buried 139 personals. The study focuses on geospatial analysis and simulation of Shishper glacial avalanche of Hunza basin. To simulate the potential glacial avalanche hazard to Hassan Abad settlements, an empirical process based Glacier Avalanche Model; Rapid Access Mass Movement Simulation (RAMMS) is utilized. The model encompasses avalanche release area and height for the execution of simulation. The model output of Shishper glacial avalanche resulted; a max pressure of 450 Kpa, max velocity of 40 m/s, and the max flow height of 80m, while the resulted surge extent output was 2500m. The potential hazardous Shishper glacial avalanche remains a continuous hazard to Hassan Abad of Hunza valley including Karakoram Highway and Frontier Works Organization (FWO) camp. The study has resulted in identifying the Upper Indus Bain (UIB) being more prone to glacial avalanche hazards because of host factors in general and the anthropogenic factor in particular.

DAMMING HUNZA RIVER BY MASSIVE ATTABAD LANDSLIDE, STORY OF A RISK MANAGEMENT INITIATIVE FROM HUNZA, PAKISTAN

The mountainous region of northern Pakistan is seismically active as Indian plate is subducting beneath the Eurasian plate. Various geological phenomena are active due to the mountain building and landslides are one of the most destructive natural disasters in the Karakoram range. The northern part of Pakistan, Gilgit-Baltistan, falling in this region is no exception to that. Attabad was a remote village situated on the right bank of Hunza River at a ground distance of almost 125 km from Gilgit city. The area falls into Darkut-Karakoram metamorphic complex composed of granites, granodiorite, and gneiss. A devastating landslide occurred on 4th January 2010, as mode of circular failure which blocked the Hunza River forming a lake behind. The debris material hit the opposite rock cliff, due to narrow gorge the landslide mass travelled downstream 1.5km with huge debris surges, hitting 8 houses in lower Attabad which came under rubble and 19 people died. Aga Khan Agency for Habitat previously FOCUS Pakistan developed an inventory of active landslides across the KKH in Hunza in 2000-2001, however this landslide was not identified. Later in 2002 after the Astore earthquake initial cracks developed at the top of the slope. The 8th October Kashmir earthquake destabilized and U-shaped demarcation appeared across the slope. Anthropogenic activities like irrigation of lands, seepage of water from rain and snow melt water further destabilized the land. Finally, an earthquake in November 2009 in Hindukush region triggered the landslide and brittle failure occurred on 4th January 2010.