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- Creators: Arizona State University
- Creators: School of Geographical Sciences and Urban Planning
- Creators: Davis, Jonathan
- Resource Type: Text
The first challenge is choosing appropriate climate metrics that are closely tied to erosional processes. For example, in fluvial landscapes, most runoff events do little to no geomorphic work due to erosion thresholds, and event-scale variability dictates how frequently these thresholds are exceeded. By analyzing dense hydroclimatic datasets in the contiguous U.S. and Puerto Rico, we show that event-scale runoff variability is only loosely related to event-scale rainfall variability. Instead, aridity and fractional evapotranspiration (ET) losses are much better predictors of runoff variability. Importantly, simple hillslope-scale soil water balance models capture major aspects of the observed relation between runoff variability and fractional ET losses. Together, these results point to the role of vegetation water use as a potential key to relating mean hydrologic partitioning with runoff variability.
The second challenge is that long-term erosion rates are expected to balance rock uplift rates as landscapes approach topographic steady state, regardless of hydroclimatic setting. This is illustrated with new data along the Main Gulf Escarpment, Baja, Mexico. Under this conceptual framework, climate is not expected to set the erosion rate, but rather the erosional efficiency of the system, or the steady-state relief required for erosion to keep up with tectonically driven uplift rates. To assess differences in erosional efficiency across landscapes experiencing different climatic regimes, we contrast new CRN data from tectonically active landscapes in Baja, Mexico and southern California (arid) with northern Honduras (very humid) alongside other published global data from similar hydroclimatic settings. This analysis shows how climate does, in fact, set functional relationships between topographic metrics like channel steepness and long-term erosion rates. However, we also show that relatively small differences in rock erodibility and incision thresholds can easily overprint hydroclimatic controls on erosional efficiency motivating the need for more field based constraints on these important variables.
to Global Climate Change. By employing a Diné philosophy based research methodology this study seeks to holistically reframe the lens that the Navajo Nation conceptualizes Global Climate Change. The study uses a comprehensive review of literature that pertained to four research questions. The research questions are: 1) What do Diné oral histories say about climate change? 2) How is the Navajo Nation going to mitigate and adapt to changes to the climate using Western knowledge? 3) How can Diné research methodologies help inform policies that will mitigate and adapt to climate change? 4) What type of actions and frameworks can the Navajo Nation use to generate meaningful policy? The study utilizes a Diné philosophy based analytical framework to focus on how climate change will affect the Diné peoples' A) spirituality, B) economic sustainability, C) family-community, and D) home-environment. The findings are: a) the Navajo spiritual ceremonies are process models that can be used to mitigate and/or adapt to climate change, and they must continue to be practiced. b) The economic development section revealed that economic security is not found solely in resource development, but in the security of ceremonial knowledge. The burden of the Navajo government however, is not to promote labor, but the ability for people to live into old age. c) Because families and communities drive Diné philosophy, Diné families and communities must remember how to treat each other with respect. The collective survival of the Navajo Nation always depended on this teaching. d) The findings of the home-environment section is that Diné have to acknowledge that their lives are fragile in the face of global climate change, and the only way that they can live happily is to trust the power of the stories of the ancestors, and seek to embody the Diné philosophy. This study succeeded as an honest attempt to apply an Indigenous Diné methodology to reframe Global Climate Change into a phenomenon that is survivable.
Numerical simulations using a state-of-the-science regional climate model are utilized to address a trio of scientifically relevant questions with wide global applicability. The importance of an accurate representation of land use and land cover is first demonstrated through comparison of numerical simulations against observations. Second, the simulated effect of anthropogenic heating is quantified. Lastly, numerical simulations are performed using pre-historic scenarios of land use and land cover to examine and quantify the impact of Mexico City's urban expansion and changes in surface water features on its regional climate.
The Phoenix area, is known for suburban sprawl which did not happen in isolation but was the result of many external factors. It was not just large environmental and cultural factors that changed over time, but the actual physical characteristics of sprawl that have changed from community to community over the decades. Characteristics like physical size of houses and lot size, along with changes in the residential and commercial design and building style have changed from around the 1950s to present day, with homes being larger and covering more of each parcel. These characteristics were analyzed in 21 communities in the Phoenix area that were built from 1950 to 2019 to find how these characteristics have changed over time. While the issue of sprawl will never fully go away, by learning what the characteristics are that make up the definition of sprawl, stakeholders like cities, planners, and developers will have better knowledge for planning for tomorrow.