Evaluating wetland extent trends using remote sensing: case studies in the Canadian Rockies
No Thumbnail Available
Date
2025
Authors
Rodrigues, Italo Sampaio
University of Lethbridge. Faculty of Arts and Science
Journal Title
Journal ISSN
Volume Title
Publisher
Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment
Abstract
Mountainous wetlands provide critical ecosystem services, but their sustainability is increasingly threatened by climate change impacts on river flow, runoff regimes, and landscape dynamics. The main objective of this thesis is to investigate how wetland hydrology and land cover in two mountainous regions, the Upper Columbia floodplain in British Columbia and the Eastern Slopes of Alberta (ES), are changing over time and how they could react under future climate scenarios. The specific aims of this thesis are to: 1) Evaluate historical and projected changes in wetland land cover and hydrology in the Upper Columbia River floodplain (1984–2040); 2) Apply and expand these methods to the ES (1984–2023); 3) Quantify open water evaporation relative to forest ecosystem evapotranspiration volumes, and assess seasonal variations between the snowmelt- and rainfall-dominated periods.
Results on Objective 1 indicate that from 1984 to 2022 the Upper Columbia floodplain has already undergone significant hydrological and ecological changes. Peak river discharge now occurs eleven days earlier and with shorter duration, so generating greater peak flows over a shorter period. These shifts have matched a drying trend in wetland habitats and a transition to woody and shrubby vegetation. Under both RCP 4.5 and RCP 8.5, projected data (2020s–2040s) show a continuous reduction in late-summer open water areas; the seasonal peak shifts earlier into spring (April to mid-May). Applying a similar analytical approach to the ES in Objective 2 revealed both parallel and contrasting trends. In the snowmelt-dominated period (late May to mid-July), subalpine (≤2300 m) and alpine (>2300 m) regions experienced increases in open water, non-woody, and woody/shrub vegetation while barren land decreased. On the other hand, the rainfall-dominated period (late July to mid-September) revealed a decline in open water area and an increase in barren land, so suggesting possible seasonal water constraints and vegetation changes. For Objective 3, the estimated proportion (P%) of open water evaporation in relation to volumes of forest ecosystem evapotranspiration. Historically, P% was 2.4% during the snowmelt-dominated period and 2.1% during the rainfall-dominated period. Especially in earlier stages of the hydrologic year, these trends indicate rising contributions of surface water bodies to total evapotranspiration. The consequences comprise changed water availability, habitat changes, and the long-term viability of wetland ecosystem services. The noted seasonality of hydrological changes and acceleration highlights the need for adaptive water management and conservation strategies considering local and regional dynamics.
Description
Keywords
open water , climate change , land cover trends , forecast , water resources , Landsat archive