Vulnerability and decision risk analysis in glacier lake outburst floods (GLOF). Case studies : Quillcay sub basin in the Cordillera Blanca in Peru and Dudh Koshi sub basin in the Everest region in Nepal

textGlacial-dominated areas pose unique challenges to downstream communities in adapting to recent and continuing global climate change, including increased threats of glacial lake outburst floods (GLOFs) that have substantial impacts on regional social, environmental and economic systems increasing risk due to flooding of downstream communities. In this dissertation, two lakes with potential to generate GLOFs were studied, Imja Lake in Nepal and Palcacocha Lake in Peru. At Imja Lake, basic data was generated that allowed the creation of a conceptual model of the lake. Ground penetrating radar and bathymetric surveys were performed. Also, an inundation model was developed in order to evaluate the effectiveness of a project that seeks to reduce flooding risk by lowering the lake at least 3 meters. In Peru, a GLOF inundation model was created. Also, the vulnerability of the people living downstream in the City of Huaraz was calculated, and the impacts of an early warning system were evaluated. The results at Imja indicated that the lake deepened from 98 m in 2002 to 116 m in 2012. Likewise, the lake volume increased from 35.8 to 61.6±1.8 million m3 over the past decade. The GPR survey at Imja and Lhotse-Shar glaciers shows that the glacier is over 200 m thick in the center of the glacier. The modeling work at Imja shows that the proposed project will not have major impacts downstream since the area inundated does not reduce considerably unless the lake is lowered by about 20 m. In Huaraz, the results indicate that approximately 40646 people live in the potentially inundated area. Using the flow simulation and the Peru Census 2007, a map of vulnerability was generated indicating that the most vulnerable areas are near the river. Finally, the potential number of fatalities in a worst case GLOF scenario from Lake Palcacocha was calculated to be 19773 with a standard deviation of 1191 if there is no early warning system and 7344 with a standard deviation of 1446 people if an early warning system is installed. Finally, if evacuation measures are improved the number reduces to 2865 with a standard deviation of 462.Civil, Architectural, and Environmental Engineerin

Use of WRF-Hydro over the Northeast of the US to Estimate Water Budget Tendencies in Small Watersheds

In the Northeast of the US, climate change will bring a series of impacts on the terrestrial hydrology. Observations indicate that temperature has steadily increased during the last century, including changes in precipitation. This study implements the Weather Research and Forecasting (WRF)-Hydro framework with the Noah-Multiparameterization (Noah-MP) model that is currently used in the National Water Model to estimate the tendencies of the different variables that compounded the water budget in the Northeast of the US from 1980 to 2016. We use North American Land Data Assimilation System-2 (NLDAS-2) climate data as forcing, and we calibrated the model using 192 US Geological Survey (USGS) Geospatial Attributes of Gages for Evaluating Streamflow II (Gages II) reference stations. We study the tendencies determining the Kendall-Theil slope of streamflow using the maximum three-day average, seven-day minimum flow, and the monotonic five-day mean times series. For the water budget, we determine the Kendall-Theil slope for changes in monthly values of precipitation, surface and subsurface runoff, evapotranspiration, transpiration, soil moisture, and snow accumulation. The results indicate that the changes in precipitation are not being distributed evenly in the components of the water budget. Precipitation is decreasing during winter and increasing during the summer, with the direct impacts being a decrease in snow accumulation and an increase in evapotranspiration. The soil tends to be drier, which does not translate to a rise in infiltration since the surface runoff aggregated tendencies are positive, and the underground runoff aggregated tendencies are negative. The effects of climate change on streamflows are buffered by larger areas, indicating that more attention needs to be given to small catchments to adapt to climate change

Changes in Imja Tsho in the Mount Everest Region of Nepal

Imja Tsho, located in the Sagarmatha ( Everest) National Park of Nepal, is one of the most studied and rapidly growing lakes in the Himalayan range. Compared with previous studies, the results of our sonar bathymetric survey conducted in September of 2012 suggest that its maximum depth has increased from 90.5 to 116.3 +/- 5.2 m since 2002, and that its estimated volume has grown from 35.8 +/- 0.7 to 61.7 +/- 3.7 million m(3). Most of the expansion of the lake in recent years has taken place in the glacier terminus-lake interface on the eastern end of the lake, with the glacier receding at about 52 m yr(-1) and the lake expanding in area by 0.04 km(2) yr(-1). A ground penetrating radar survey of the Imja-Lhotse Shar glacier just behind the glacier terminus shows that the ice is over 200 m thick in the center of the glacier. The volume of water that could be released from the lake in the event of a breach in the damming moraine on the western end of the lake has increased to 34.1 +/- 1.08 million m(3) from the 21 million m(3) estimated in 2002.USAID Climate Change Resilient Development (CCRD) projectFulbright FoundationNational Geographic SocietyCenter for Research in Water Resource

Response time to flood events using a social vulnerability index (ReTSVI)

Current methods to estimate evacuation time during a natural disaster do not consider the socioeconomic and demographic characteristics of the population. This article develops the Response Time by Social Vulnerability Index (ReTSVI). ReTSVI combines a series of modules that are pieces of information that interact during an evacuation, such as evacuation rate curves, mobilization, inundation models, and social vulnerability indexes, to create an integrated map of the evacuation rate in a given location. We provide an example of the application of ReTSVI in a potential case of a severe flood event in Huaraz, Peru. The results show that during the first 5&thinsp;min of the evacuation, the population that lives in neighborhoods with a high social vulnerability evacuates 15&thinsp;% and 22&thinsp;% fewer people than the blocks with medium and low social vulnerability. These differences gradually decrease over time after the evacuation warning, and social vulnerability becomes less relevant after 30&thinsp;min. The results of the application example have no statistical significance, which should be considered in a real case of application. Using a methodology such as ReTSVI could make it possible to combine social and physical vulnerability in a qualitative framework for evacuation, although more research is needed to understand the socioeconomic variables that explain the differences in evacuation rate.</p

Contrasting geometric and dynamic evolution of lake and land-terminating glaciers in the central Himalaya

The impact of glacial lake development on the evolution of glaciers in the Himalaya is poorly quantified, despite the increasing prevalence of supraglacial and proglacial water bodies throughout the region. In this study we examine changes in the geometry, velocity and surface elevation of nine lake-terminating and nine land-terminating glaciers in the Everest region of the central Himalaya over the time period 2000 to 2015. The land-terminating glaciers we examined all decelerated (mean velocity change of −0.16 to −5.60 m a‾¹ for different glaciers), thinned most in their middle reaches, and developed a more gently sloping surface (−0.02 to −0.37° change) down-glacier over the period 2000–2015. The lake-terminating glaciers we examined all retreated (0.46 to 1.42 km), became steeper (0.04 to 8.68° change), and showed maximum thinning towards their termini, but differed in terms of their dynamics, with one group of glaciers accelerating (mean speed-up of 0.18 to 8.04 m a‾¹) and the other decelerating (mean slow-down of −0.36 m a−1 to −8.68 m a‾¹). We suggest that these two scenarios of glacier evolution each represent a different phase of glacial lake expansion; one that is accompanied by increasingly dynamic glacier behaviour and retreat, and a phase where glacial lakes have little impact on glacier behaviour that may precede or follow the phase of active retreat. Our observations are important because they quantify the interaction of glacial lake expansion with glacier ice mass loss, and show that increased glacier recession should be expected where a glacial lake has begun to develop

Floodplain Analysis of Sanderson Texas - HEC-HMS

Hydrologic modeling and calculations using HEC-HMS and HEC-GeoHMS for the 100-year storm for Sanderson, Texas.UT-AustinCivil, Architectural, and Environmental Engineerin

Evaluating Multiple WRF Configurations and Forcing over the Northern Patagonian Icecap (NPI) and Baker River Basin

The use of numerical weather prediction (NWP) model to dynamically downscale coarse climate reanalysis data allows for the capture of processes that are influenced by land cover and topographic features. Climate reanalysis downscaling is useful for hydrology modeling, where catchment processes happen on a spatial scale that is not represented in reanalysis models. Selecting proper parameterization in the NWP for downscaling is crucial to downscale the climate variables of interest. In this work, we are interested in identifying at least one combination of physics in the Weather Research Forecast (WRF) model that performs well in our area of study that covers the Baker River Basin and the Northern Patagonian Icecap (NPI) in the south of Chile. We used ERA-Interim reanalysis data to run WRF in twenty-four different combinations of physics for three years in a nested domain of 22.5 and 4.5 km with 34 vertical levels. From more to less confident, we found that, for the planetary boundary layer (PBL), the best option is to use YSU; for the land surface model (LSM), the best option is the five-Layer Thermal, RRTM for longwave, Dudhia for short wave radiation, and Thompson for the microphysics. In general, the model did well for temperature (average, minimum, maximum) for most of the observation points and configurations. Precipitation was good, but just a few configurations stood out (i.e., conf-9 and conf-10). Surface pressure and Relative Humidity results were not good or bad, and it depends on the statistics with which we evaluate the time series (i.e., KGE or NSE). The results for wind speed were inferior; there was a warm bias in all of the stations. Once we identify the best configuration in our experiment, we run WRF for one year using ERA5 and FNL0832 climate reanalysis. Our results indicate that Era-interim provided better results for precipitation. In the case of temperature, FNL0832 gave better results; however, all of the models&rsquo; performances were good. Therefore, working with ERA-Interim seems the best option in this region with the physics selected. We did not experiment with changes in resolution, which may have improved results with ERA5 that has a better spatial and temporal resolution

Bathymetric survey of Imja Lake, Nepal in 2012

Imja Lake is one of the most studied lakes in the Himalaya as well as one of the most rapidly evolving glacial lakes in Nepal. Many researchers have studied the lake and the potential of a glacier lake outburst flood from the lake. One of the important factors in assessing the outburst flood risk is the volume that could be released in the flood and good bathymetric data is necessary to estimate that value. This work reports on the 2012 bathymetric survey of Imja Lake and the rate of expansion that has been observed in the lake over the last two decades, since 1992. The survey was somewhat hampered by the extensive iceberg coverage of the lake in September 2012, but a good estimate of the bottom bathymetry and the current volume was obtained. When compared to previous surveys, it is very clear that the lake bottom has continued to deepen as the ice beneath the lake has melted. The average depth has increased by 62% since 2002 and continues to increase at a rate of 1.8 m/yr. The maximum depth has increased 28% since 2002 and is increasing currently at a rate of 5.8 m/yr. Perhaps more important in terms of glacier lake outburst flood risk is the continued rapid areal expansion of the lake which has expanded 41% since 2002 and is growing at a rate of 0.02 km2/yr. This expansion has resulted in an additional 6 million m3 of water for an outburst flood event, and increasing the maximum possible flood volume to 36.3 million m3 a 73% increase from what was calculated using 2002 data.Center for Research in Water Resource

Chile’s glacier protection law needs grounding in sound science

Glaciers have long been thought of as static, picturesque totems or as changeless coverings over permanently frozen landscapes, particularly among societies distant from mountains and the poles. However, as traditional mountain cultures with firsthand experience have long known and treasured—and as glaciologists, hydrologists, and climate scientists have deciphered and communicated—glaciers are by no means static. Rather, they are dynamic landscape agents and unmistakable indicators of rapid environmental transformation [Gagné et al., 2014]. With widespread media coverage of anthropogenic climate change and the realization that glaciers are endangered species [Carey, 2007], popular perceptions are gradually changing, and scientists, grassroots movements, and policymakers are increasingly committing to developing legal protections for glaciers

Ground penetrating radar survey for risk reduction at Imja Lake, Nepal

This study presents observations of the structure of the terminal moraine complex at Imja Lake. Detailed ground penetrating radar (GPR) surveys were conducted at Imja Lake. The lake and the surrounding Imja glacier have been described in the previous section. This paper should contribute to the understanding of the structure of the terminal moraine and the distribution of ice in the core of the moraine. The formation of glacier lakes in the Nepal Himalaya has been increasing since the early 1960s. Accompanying this increase in the number and size of glacier lakes is an associated number of GLOF events. The Khumbu region of Nepal (which includes the Dudh Koshi basin) is regularly mentioned as an area particularly prone to GLOF events and containing important sites for possible GLOF risk reduction projects (especially in the Imja Khola). Imja lake in the Khumbu is often mentioned as a potentially dangerous glacier lake (PDGL) and its GLOF risk has been investigated for more than 20 years (Armstrong, 2010). In May and September 2012, the authors visited the lake and observed the rapid rate of change of the terminal moraine complex. They performed ground penetrating radar surveys of most of the terminal moraine complex and mapped the ice core of the moraine. Imja Lake is currently the focus of several groups in an effort to reduce the risk of a GLOF posed by the increasing lake level. The presence or absence of ice in the core of the terminal moraine complex is of critical importance in designing a risk reduction program for the lake. This work has used Ground Penetrating Radar (GPR) to investigate the internal structure of the moraine complex in order to map out the ice thickness in critical areas. The results of the GPR survey show that there is extensive ice present in the core of the terminal moraine complex at Imja Lake (see Figure 8). The thickest areas of ice are in the moraine near the western end of the lake on the northern side of the lake outlet. The ice in this region is several tens of meters thick and up to fifty meters thick in some places. Along the northern and southern sides of the lake outlet, the ice is between ten and twenty-five meters thick. In some portions of the moraine on the southern side of the outlet the ice thickness is up to forty meters. Extensive seepage of water from the terminal moraine was observed in two locations during visits to the lake in September 2011, May 2012, and September 2012. GPR transects above and below the site of seepage show the presence of ice above the seep and much less ice below the seep. Seepage of water through the terminal moraine is an indication of potential weakness in the moraine and a possible site of future moraine failure. Recent work has been initiated by the United Nations Development Programme to develop an Imja Lake Risk Reduction Program. One of the primary methods suggested for reducing risk associated with the lake is to reinforce and deepen the outlet channel so that it can lower the lake level up to 3 meters below the current level. This project involves making excavations of the outlet channel and the construction of a diversion channel on the southern side of the outlet. The results presented here indicate that there may be ice present in the moraine in the vicinity of the excavations being considered in this project. Excavation activities that encounter ice in the moraine material may cause weakening of the ice resulting in increased water seepage and erosion of the moraine. Therefore, it is recommended that additional GPR surveys be conducted in this area accompanied with Electrical Resistivity Tomography (ERT) surveys. The ER surveys will be able to more definitively indicate the presence of ice in the moraine as well as the degree of water saturation of the moraine material.Center for Research in Water Resource