Damage Assessment and Triggering Mechanism of Flash Flood Event Occurred in Reshun During 2013 using Remote Sensing and GIS Techniques

Abstract

Floods are the most dreadful events so far in the history of Pakistan as well as the whole world. And the damages caused by these floods are terrible. The main purpose of this Research is to determine the possible reasons behind the devastating flood of Reshun 2013, and damages assessment of the flood. It has been perceived that Global climate change is root to retreat of the glacier throughout the world. In Pakistan, at the gate-way to Himalaya or in Alaska, there are signs everywhere that ice melting is accelerating, but the rate of glacier melting in Pakistan is low as compared to the glaceirs of other regions, as well as in Pakistan some glaciers are stable or surging instead, While climate disasters are becoming more frequent. Keeping Pakistan in view, as being a developing country moreover confronting climate changes and global warming, this warming drift in Pakistan is diverst for distinctive districts. Chitral is exceptionally a long history of glacier lake outburst (GLOF). The study area is a historic village in the Reshun valley located north of the capital city of Chitral .at .a .distance .of 55 .km it falls .between latitude N 36 10 23.10 and longitude E 72 7 8.2 which is located in the northwest of Pakistan between from the Karakoram. The village consists of 8 small and large villages. It is estimated that .there .are .about .800 residents living in .households with a .population .of .about 7,000 .souls. Rashun .village .is .located .on .the west .bank .of the .Chitral River .on the .Chitral .Mastuj main .road. The .average .elevation .of .the Rashun River above .sea .level .is 6225 Ft. Rashun .is .famous .for .its .nutritious .fruits, .cultural .activities, .honey .production .and charismatic landscape. The main source of livelihood is agriculture and orchards growing in .both the .public .and .private .sectors. One of the main land features in Rashan that is our main concern are the 'glaciers' which are about 1400 feet above sea level. There are so many facts that prove the instability of the glaciers in the Rashun Valley. 1. Glaciers have steep slopes supported by fragile moraines. 2. Terminal moraines have many cracks that make them weak enough to withstand internal or external hydraulic pressure. 3. The instability of the valley is increased by the fact that the Rashun Valley is located on the Rashun fault. Weather data showed that July 2013 was slightly warmer than the previous years of 2010, 2011 and 2012. However, the daily temperature difference from .July 19 to 31 was significant compared DRSML QAU xi to previous years. The average minimum temperature recorded in Chitral was 23C during 19-31 July and the maximum average temperature during this period was 39c and minimum temperature 26C was recorded on 28-29 July 2013. Climate of this region is normally dry temperate, precipitation is received generally during winters. Little or no rainfall was recorded in the month of July in the Chitral region which was closely monitored for flash floods. The Hindukush region near Chitral has experienced a number .of .earthquakes .and .seismic .activity .of .varying .magnitude. Chitral experienced earthquakes of varying strength throughout July. In a weak mountain ecosystem, earthquakes and seismic activities are considered to be the main causes of floods from glacial lakes. During the last two weeks of July, a severe heat wave associated with physically vulnerable features of the glaciers developed. Different satellite imagery from landsat 7, landsat 8 was accessed and processed using ArcGIS to marked damages caused by the flash flood of Reshun 2013. There were huge damages including forest areas, houses, crops, pedestrian bridges, Roads as well as the path-way of Reshun River is also damaged a lot. Overall area damaged by the devastating flood was 145,333.046633 square meter. Whereas the crops damaged area is 34,815.199757 square meter, Forest damages are 33951.889916 square meter, 3,773.606715 Square meter area comprising on houses has been damaged by flash flood of Reshun, 2013.