Date of Award

2016

Document Type

Open Access Master's Report

Degree Name

Master of Science in Geological Engineering (MS)

Administrative Home Department

Department of Geological and Mining Engineering and Sciences

Advisor 1

John Gierke

Committee Member 1

Ann Maclean

Committee Member 2

Joseph Wagenbrenner

Abstract

Evidence suggests that a changing global climate is accelerating glacial retreat around the world. However, there are not many studies that help to understand the influence of climate change on glaciers in the tropical Andes. In many Andean countries, populations use the water that come from the high altitude mountains, especially mountains that are ice covered. Glacial reduction minimizes water resource availability. This report focuses on better understanding the relationship between glacier meltwater, surface water runoff, and the groundwater flowing into and under the Pita River upper watershed, which crosses the base of the northeast foothills of the Cotopaxi volcano. Available geospatial, meteorological, hydrogeological, and geochemical data were used in order to calculate the water balance, as well as to evaluate the chemical signature of the water sources for different creeks lakes and rivers into the study area. The results achieved in this work are the annual temperature is 8.41 ° C, whereas the annual rainfall is 1320 mm and the evapotranspiration is around 38-43% of the precipitation value. Hydrological conditions generated a water yield in the watershed of 17.9 l/s/km2. According to the relationship between area and discharge, for the Pita watershed with an area of 173 km2, the discharge corresponds to 3.1 m3/s. Thus, the Cotopaxi hillslope contributes 33% to the total yield, which is equivalent to 1021 l/s. The volume of the glacier retreat from 1996 to 2010 is 0.013 km3 and is considered as part of the glacier meltwater contribution. Regarding to the isotopic signature, all the samples taken show a mixture signature between the two possible sources, which means that there is infiltration in the upper part of the watershed and discharge in the lower part of it. These results were ascertained in the context of current climatic conditions in a conceptual model that will be used to estimate how the glacial contributions might change as a result of future climate changes and the impacts of these changes on water supplies in this region.

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