Precipitation and air temperature links to stream flow in Glacier Bay

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Abstract

Groundwater temperature is a key parameter regulating the ecological balance of the ecosystems in groundwater dominated wetlands, estuaries and ponds. This study evaluated the potential impacts of climate change on groundwater temperature and proposed a methodology for use in areas with limited hydrological and metrological data. Groundwater temperatures were measured in 1 m intervals in five observation wells and used for groundwater recharge estimation. Three different techniques, the water balance method, the water level fluctuation (WLF) method and Darcy's method, were performed to verify the estimated recharge rates from the temperature-depth profiles. Of the six sets of global climate model (GCM) predictions analysed, three of them were selected by considering a range of potential climate changes in the future. The findings from the methodology developed here will be important for estimating the impact of climate change and will be useful for environmental management programs.

Table of Contents

ABSTRACT2

Background4

Glacial Isostatic Adjustment5

Pacific North American Pattern6

CHAPTER 2: LITERATURE REVIEW7

History7

Climate8

Landscape8

Glaciers9

The Historical Context13

Periglacial Environments, Periglacial Ecosystems14

Glacier Bay National Park and Preserve14

Environement15

CHAPTER 3: METHODOLOGY20

GCM selection for the analysis20

Spatial downscaling21

Analytical model for subsurface temperature distribution22

Study area and field observations22

Surface runoff estimation23

Groundwater recharges estimation from temperature-depth profiles25

Groundwater recharges estimation from the water budget technique27

Groundwater recharge estimation from Darcy's law27

CHAPTER 4: RESULTS AND ANALYSIS30

Recharge estimations from water level fluctuation (WLF) method30

Spatial downscaling31

Temperature downscaling32

Combined effect of surface warming and groundwater recharge variations34

Data Analysis38

Relating climate variables to water quality variables38

Configuration of the river39

Sensitivity of the results41

CHAPTER 5: CONCLUSION43

REFERENCES46

CHAPTER 1: INTRODUCTION

Background

Climate change poses a serious threat to freshwater resources and their indispensable role in all terrestrial ecosystems. The fourth assessment of the Intergovernmental Panel on Climate Change (Parry et al., 2007) concluded that approximately 20-30% of plant and animal species that have been assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1•5-2•5 °C. In recent years, there has been increasing research in predicting the potential impact of climate change on fresh water quantity and quality. However, there has been little attention paid to groundwater and even less attention to groundwater temperature.

From an ecological point of view, water temperature is one of the main parameters that directly influence the metabolic rate of organisms and the overall productivity of ecosystems. Increases in water temperatures as a result of climate change will alter fundamental ecological processes and the geographic distribution of aquatic species in groundwater-dominated wetlands, estuaries, and ponds. Both ground surface temperature change and variations in groundwater flow patterns will alter the aquifer thermal regime, because heat in the subsurface layer is transported not only by conduction, but also by convection through the groundwater.

Assessing the anticipated impacts of climate change requires predicting the future behaviour of the global climate system. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) gives a set of Global Climate Models (GCMs) (e.g. HADCM3 from the UK, MRI from Japan, and GFDL from USA) with a well standardized group of scenarios (e.g. A2, A1B, and B1) for climate ...