A thesis for the Bachelor of Geographic Information Systems degree from Selkirk College’s Environment and Geomatics.
Through this website I hope to explore how human use of spaces alters the dynamics of natural processes, through habitat destruction, careless resource depletion and extraction, or changes to the hydrological cycle. This research is the first phase in a 3-phase project to improve our understanding of how land use choices and climate change are affecting aquifer recharge within the Columbia Basin. Focusing our research on using aquifer recharge potential mapping, which is a process of using different spatial and statistical tools to identify areas where the interaction between slope, precipitation, aquifer geology, soil permeability, and land use are used to derive various aquifer recharge potentials (very poor, poor, moderate, good, and very good). Furthermore, I used a multicriteria decision making process known as the Analytical Hierarchical Process, which allowed for pair-wise comparisons between the variables mentioned. The resulting analysis showed that of the studied aquifers, 57% had moderate recharge potential, 24% fell under poor, and 17% under good. Through our results, we hoped to better understand the current state of aquifer recharge within the Columbia Basin, and the implications that these bring in the face of human pressures through industrial and domestic use, as well as climate change.
Using this map below, you are able to select different layers, look for aquifers using the search bar, and see information regarding aquifer recharge potential and land use.
Through the use of Aquifer Recharge Potential Mapping , in combination with a multicriteria decision making process (AHP), aquifer recharge potential was identified on all the mapped aquifers within the Columbia Basin. Aquifers which showed a mostly poor to moderate recharge potential (such as Cranbrook, Creston, and Winlaw/Slocan) face challenges around the increasing demand for water resources. Due to a high human use and demand, and a poor recharge capacity, aquifers within this category should be managed according to the possibilities that these aquifers are being depleted at a faster level that they are being refilled by natural processes (Machiwal et al. 2011). Furthermore, changing environmental conditions could also begin influencing the only forms of recharge which these aquifers depend on. With a changing hydrological regime (less precipitation in the form of snow), aquifers in the poor to moderate category are especially susceptible to overuse. Aquifers which showed a good recharge potential (such as the Grand Forks aquifer) face a similar, but perhaps more complicated issue. As pointed by Fostner et al. (2018), aquifer vulnerability is partly assed by how easy a pollutant can infiltrate into an aquifer. Good aquifer recharge around the Grand Forks aquifer leaves the aquifer vulnerable to possible pollution from various human and industrial land uses. This could be devastating in combination with changing hydrological and climatic patterns, as aquifers become stressed from lower inputs, having contamination could mean the end of the use of an aquifer. The resulting overlay analysis provides the first look into the possible areas of aquifers within the Columbia Basin could be at risk of being impacted by various human land uses using Aquifer Recharge Potential Mapping. The wide range of possible aquifer recharge potential show that all aquifers are at some kind of risk and variability dependant on the variables examined. Areas most at risk are aquifers with higher rates of poor and good aquifer recharge potential due to their propensity to drying out, and to becoming polluted. These areas could be key to maintaining a healthy and stable water reserve in the future, specially with climate conditions and their projected changes. Hence, the protection of these aquifers calls for a wholistic approach to water management depending on the specific aquifer. The web mapping application is also the first prototype of a tool which includes this type of analysis that can be used to implement better decision making both at the citizen level (agricultural producers), as well as higher level orders of decision making (government organizations). It allows citizens and property owners to access information about their local area, which provide them with the necessary tools to make educated decisions about their agricultural practices. One possible example would be the designation of specific practices for agriculture of both crops and animals. In the Grand Forks Aquifer for example, which has generally better recharge potential, a more controlled use of nutrients and disposal of animal waste away from water ways can help protect it from pollution. On the other hand, in aquifers such as the Cranbrook Aquifer, which have generally poorer recharge potential, more careful planning and best practices about water quantity use should be considered. This could be accomplished by identifying areas which are of concern (such as the areas identified previously) and provide the agricultural producers with the knowledge and support to choose the right irrigation systems, crops, and monitoring practices in order to protect the water resources they depend on. This approach to water management becomes increasingly important in areas where there is a high dependence on groundwater resources, not only for residential, but also industrial uses. Another use case scenario for these results is the for the protection of riparian ecosystems and wetlands which positively maintain the hydrological balance between surface water and aquifer recharge. Through the protection of areas which positively influence aquifer recharge potential and are within human control, can provide aquifers the possibility to maintain their discharge and recharge cycle as intact as possible.
Accuracy Considerations AHP has a major shortcoming, and it is regarding the subjective choices of values for different variables. This shortcoming makes this analysis rather exploratory and qualitative and should be interpreted and used as such. Another accuracy shortcoming arises with the varying size of aquifers and the scale of rasters. The original rasters had to be resampled to match the created aquifer subtype raster and be used in the weighted overlay analysis, reducing their original accuracy. Recommendations for the next phases and accuracy improvements are given in the discussion section below.
This study found a variety of limitations around data availability, scale, and the variables for the analysis. One recommendation is to include hydraulic connectivity of surface and groundwater. Hydraulic connectivity (Wei et al 2009), or whether an aquifer is directly connected to a stream, would provide another important layer for analysis which would allow for an analysis more focused on the recharge source of each aquifer. Another recommendation is to Run the model with additional inputs such as iterating the precipitation data to reflect different climate scenarios. This would provide a deeper understanding on how climate change could further influence aquifer recharge in the Columbia basin. The next possible steps for this project are laid out in phases 2 and 3, which will further explore and tune the first analysis. Phase 2 will expand accuracy testing and decision-making model improvement and improve on the user interface for the web map. This phase will also explore the possible effects that changes in precipitation and the form of precipitation may have in our aquifers. Phase 3 is the last phase, and it aims to bring together the results from phase 1 and phase 2 by quantifying the aquifer recharge of aquifers in the Columbia Basin, hopefully providing the public with a tool to carry out sensible decision and policy making choices. In conclusion, this research hopes to bring forward the idea that the land use decisions, and practices that we carry out in agriculture and other industries which we depend on, have a long-lasting impact on the hydrological cycle of aquifers. With that knowledge however, we are provided with the power to be able to make sound decisions taking into consideration all our surrounding natural gifts.
To access the full thesis please click the link below