Between aspiration and actuality: A systematic review of morphological heat mitigation strategies in hot urban deserts

The rising risks of thermal extremes are among the largest global threats. They are significant in hot urban deserts (HUDs) given the already high air temperatures, urban-induced heating, and vulnerability of residents. The challenge compounds as localities combat urban heating with mitigative approaches unmindful of on-ground constraints in hot desert environments. Based on a systematic literature review, this study investigates the current state of knowledge of morphological heat mitigative interventions in HUDs. First, metrics, measurements, and methods were extracted to examine the applicability of different interventions. Then, a content synthesis identified the levels of strategy success. Lastly, challenges and uncertainties were identified to compare mitigation aspirational aims from their actualities. For hot urban deserts, the results indicate opportunities to use seldomly investigated morphological metrics such as the length of contiguous vertical facets and intermediate orientations of canyons to mitigate urban-induced heating. In addition, this study reports the methodological challenges in metric computations across scales. It revealed the impact of coupling effects and measurements approaches in defining the success of morphological mitigative interventions. The review illustrates the need to unpack complex relationships between mitigation interventions and thermal stimuli both spatially and temporally to optimize benefits and minimize tradeoffs of mitigation strategies.