Identifying urban green space deserts by considering different walking distance thresholds for healthy and socially equitable city planning in the Global South

A lingering question in the research on urban green space (UGS) availability in the Global South is which walking distance threshold should be used due to the absence of consensus on that in the literature and planning guidelines. This paper answers that question by developing an analytical framework for identifying UGS deserts – areas without adequate UGS availability level – considering various walking distance thresholds. We first demonstrate how geographic distributions of UGS deserts can change depending on different walking distance thresholds (e.g., 100, 300, 500 m) of choice. Unreliable and inaccurate detection of UGS deserts can hinder evidence-based land use planning for promoting healthy cities and result in erroneous social equity evaluation. To overcome this limitation, we introduce and examine robust UGS oases and deserts: geographic areas with and without the per capita green space (PCG) level recommended by a local government regardless of different walking distance thresholds used, respectively. With the identified robust UGS deserts and oases, we perform a social equity analysis to investigate inequality and whether there are systematic disadvantages for socioeconomically vulnerable populations to access UGS in Dhaka, a rapidly developing capital city in Bangladesh. The robust UGS deserts approach enables more reliable and informed decision-making to enhance UGS availability and its social equity, thereby facilitating an optimal development of urban policy for healthy cities. More practically, our robust UGS deserts method can be an effective alternative to detect UGS deserts when guidelines for walking distance thresholds are missing which is often the case in low- and middle-income countries.