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

Luna Khirfan,Ben Daub,Niloofar Mohtat

doi:10.3389/frwa.2021.754679

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, andin situobservations 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.

Highlights

FLUVIAL RECLAMATIONAND THE LOSS OF URBAN STREAMSTwentieth century rapid urbanization increased the demand on developable land in urban areas, which often led to land reclamation
We investigate in this study the impacts of the loss of an urban stream in Amman, Jordan’s capital on the urban form and on ecosystem services
There is a dearth of studies that connect the culverting of urban streams to urban form in general, and in particular, in cities located in water-scarce hot and dry regions in developing countries

Summary

Introduction

FLUVIAL RECLAMATIONAND THE LOSS OF URBAN STREAMSTwentieth century rapid urbanization increased the demand on developable land in urban areas, which often led to land reclamation. While most of the discourse focuses on coastal land reclaimed from the sea, an often-overlooked type is fluvial reclamation–i.e., the reclamation of land from urban streams and rivers by culverting them and diverting them into underground pipes. Akin to coastal land reclamation, fluvial land reclamation facilitates land development over the culverted or channeled urban streams and rivers. Many urban streams, and their associated ecosystem services, disappeared from the urban landscape (Broadhead et al, 2015). The rise of environmental awareness since the 1970s and, more recently, the increasingly accelerating risks from climatic hazards, led to calls for nature-based interventions that restore and/or reintroduce lost ecosystems, and by consequence, their services, into the urban landscape (Kabisch et al, 2016), among which is the daylighting (i.e., de-culverting) of buried streams (Wild et al, 2019). Stream daylighting refers to “the practice of removing streams from buried conditions and exposing them to the Earth’s surface in order to directly or indirectly enhance the ecological, economic and/or socio-cultural well-being of a region and its inhabitants”(Khirfan et al, 2020a, p. 10)

Results

Discussion

Conclusion