Reading an Urban Palimpsest: How the Gradual Loss of an Urban Stream Impacts Urban Form's Connections and Ecosystem Functions

Abstract

Fluvial reclamation to facilitate urban development leads to culverting, hence, a loss of urban streams. Using the palimpsest analogy, we examine how the Amman Stream in Amman (Jordan) historically provided regulatory and socio-cultural ecosystem services through its socio-spatial (longitudinal, lateral, and vertical) connections. We then explore the impact of the stream's culverting, partially in 1967 then completely in 1997, on these connections and, consequently, on ecosystem services. To overcome data paucity, our methodology relied on constructing spatial data by georeferencing and digitizing aerial photos and satellite images (from 1953, 1975, 1992, and 2000) using ArcGIS. We augmented our data with archival research (historic and contemporary documents and maps), an online survey among Amman's residents, and in situ observations and photography. The results reveal striking contrasts between the historic and contemporary configuration of urban form vis-à-vis the Amman Stream. Throughout its early urban history during the Classical and early Islamic periods, the urban form elements reflected reverence and prudence toward the Amman Stream as manifested in the investment in water infrastructure and the alignment of thoroughfares, civic monuments, and bridges that collectively capitalized on the land relief (the strath) and established strong connections with the Amman Stream, maximizing, in the process, its regulatory and socio-cultural services. In contrast, the contemporary urban form replaced the stream with car-oriented roads, hence, eradicated its regulatory services and replaced its socio-spatial connections with urban socio-economic and cultural fissures. Accordingly, we propose to daylight (de-culvert) the Amman Stream to restore its regulatory and socio-cultural services and its socio-spatial connections. We substantiate the feasibility of daylighting through: (1) morphological analysis that reveals that roads cover most of the stream; (2) the survey's findings that indicate public support; and (3) the cascading benefits for the larger watershed in a water insecure region.

Back to the surface – Daylighting urban streams in a Global North–South comparison

“…In the headwater area of the Moselle River (France), 41% of the total length of streams became canalized (Le Bihan, 2009). Similar developments occurred in the North America (see Khirfan et al, 2021 for a global review), e.g., in Baltimore City (USA), 66% of all streams were buried (Elmore and Kaushal, 2008). In the Global South, stream burial is subject to similar drivers as in the Global North, however, the enormous speed of urbanization in the past decades (United Nations, 2019) has caused a superposition of different impacts on urban hydrosystems, which further complicates their restoration, among other problems (Wantzen et al, 2019…”

“…As with other human impacts on flowing water systems, stream burial began much earlier in the Global North than in the Global South (Wantzen et al, 2019;Khirfan et al, 2021). In most of Western Europe, the peaks of urbanization (and their consequences on aquatic socio-ecosystems) took place in the mid-19th and mid-20th centuries (Wolf et al, 2021;Lestel et al, 2022).…”

“…They may also introduce sediment and debris (Wild et al, 2011) or alter the sewage chemistry (Broadhead et al, 2013). A case study in a water-scarce city, Amman in Jordan, revealed such specific consequences of stream burial: the loss of regulatory and socio-cultural ecosystem services (Khirfan et al, 2021).…”

“…The examples cited above show that in old urban agglomerations, traces of streams buried centuries ago may be difficult to reveal, as reliable hydrographical maps are rarely available. Moreover, specifically in fast-developing cities, the intergenerational memory and the cultural relatedness to urban water bodies have often been interrupted (Wantzen et al, 2019;Khirfan et al, 2021). This makes it difficult to identify candidate streams for daylighting.…”

“…Restoration engineers are rarely trained for these activities. Collaboration with historians is highly recommendable, as the rediscovery of the historical heritage of urban streams may become a strong element of motivation for daylighting (Broadhead et al, 2013;Khirfan et al, 2021;Usher et al, 2021). In the following, we describe the historical development of urban streams in a mid-sized western European city and their rediscovery.…”