Kelly Shannon

Green–blue water in the city: quantification of impact of source control versus end-of-pipe solutions on sewer and river floods

Urbanization and climate change trends put strong pressures on urban water systems. Temporal variations in rainfall, runoff and water availability increase, and need to be compensated for by innovative adaptation strategies. One of these is stormwater retention and infiltration in open and/or green spaces in the city (blue-green water integration). This study evaluated the efficiency of three adaptation strategies for the city of Turnhout in Belgium, namely source control as a result of blue-green water integration, retention basins located downstream of the stormwater sewers, and end-of-pipe solutions based on river flood control reservoirs. The efficiency of these options is quantified by the reduction in sewer and river flood frequencies and volumes, and sewer overflow volumes. This is done by means of long-term simulations (100-year rainfall simulations) using an integrated conceptual sewer-river model calibrated to full hydrodynamic sewer and river models. Results show that combining open, green zones in the city with stormwater retention and infiltration for only 1% of the total city runoff area would lead to a 30 to 50% reduction in sewer flood volumes for return periods in the range 10-100 years. This is due to the additional surface storage and infiltration and consequent reduction in urban runoff. However, the impact of this source control option on downstream river floods is limited. Stormwater retention downstream of the sewer system gives a strong reduction in peak discharges to the receiving river. However due to the difference in response time between the sewer and river systems, this does not lead to a strong reduction in river flood frequency. The paper shows the importance of improving the interface between urban design and water management, and between sewer and river flood management.

Indigenous Landscape Urbanism: Sri Lanka's Reservoir & Tank System

In Sri Lanka, the relation of urbanization to landscape has a long-standing tradition. The earliest Singhalese settlements – in the so-called Dry Zone of the flat coastal lowlands surrounding the central highlands – were structured in conjunction with an ingenious tank (man-made reservoir) and irrigation system, linking habitation to cultivation and sacred spaces to topography. The productive (agricultural), reflective (religious) and engineering (flood/drought control) aspects of the tank system were interdependent and worked hand-in-hand with urbanization. Over the years, these systems have fallen into disrepair. The article will develop an argument that the term ‘landscape urbanism’ has actually been standard practice for several millennia in various parts of the world. In this regard, Sri Lanka and other South (and Southeast) Asian contexts can undoubtedly benefit from the landscape urbanism discourse while their traditional organization of agricultural agglomerations can imbue the discussion with a perspective which is less formal and aesthetic and more grounded in necessity and survival tactics.

Malene Hauxner 1942 – 2012

4 Malene Hauxner 1942 – 2012 Malene Hauxner passed away on 18 January 2012. She will be remembered as a scholar with cutting-edge research in the history of modern landscape architecture. Her books Fantasiens Have (The Garden of Imagination) (1993), Open to the Sky (in Danish: Med Himlen som Loft) (2002/2003) and Supernatur (2010) are among the most important analyses of contemporary landscape architecture.

The Invention of Nature: Alexander von Humboldt’s New World

to most landscape architects for his mesmerizing and highly annotated elevation/section of the Chimborazo, a mountain in today’s Ecuadorian Andes. Humboldt’s canonical image represents a paradigm shift not only in cartography, but also in scientific reasoning itself. The exquisite 2 x 3 foot (61 x 91.4 cm) hand-coloured 1807 drawing surmises his ‘so-called Naturgemälde_an untranslatable German term that can mean a ‘painting of nature’, but which also implies a sense of unity or wholeness. It was, as Humboldt later explained, ‘a microcosm on one page’ (p. 88). Unlike the botanical system developed by Carl Linnaeus, based on collecting, classification, and mathematical abstraction, Humboldt’s idea of nature was that of a living organism animated by dynamic forces and change; it was a ‘universal profusion with which life is everywhere distributed’ (p. 88). He radically departed from the thinkers of the day such as Linnaeus, Francis Bacon, and René Descartes who were still echoing Aristotle’s view that ‘all things are made for the sake of man’ (p. 59). The drawing illustrated nature as a system in which everything was connected: the world was B o o K R E V I E W S

Preemptive design opportunities to mitigate disasters

Floods. Droughts. Cyclones (hurricanes and typhoons). Tornados. Tsunamis. Wildfires. Volcanic eruptions. Landslides. Earthquakes. World news brings the calamities of natural disasters from all corners of the planet close to home via newspapers, television, laptops, tablets, and smartphones. Meanwhile, the travesties of outright man-made disasters through armed conflict continue to flare across continents and threaten global security. Both are devastating, bring death and wreak havoc on the built and natural environment. The Norwegian Refugee Council Internal Displacement Monitoring Centre (NRC-IDMC) reported that in 2013, 22 million people were driven from their homes through a combination of mega and small natural disasters_three times more than through war and conflict in the same period. The risk of such disasters is also rising, outpacing population growth and even rapid urbanization. Global population has doubled since the 1970s and urban concentrations have tripled since that time, particularly in vulnerable countries. IDMC director, Alfredo Zamudio, claimed that ‘most disasters are as much man-made as they are natural. Better urban planning, flood defences and building standards could mitigate much of their impact’. [1]

The ‘Agency of Mapping’ in South Asia: Galle-Matara (Sri Lanka), Mumbai (India) and Khulna (Bangladesh)

The territories – cities and landscapes – of South Asia are under incredible transformation due to man-made and natural conditions. Globalisation is spatially leaving its imprint as cities and landscapes are progressively being built by an ever-more fragmented, piecemeal and ad-hoc project modus – funded by established and new-found fortunes of national and international developers and lenders, development aid projects and (often corrupt) governments. At the same time, ‘natural’ disasters are increasing in severity and frequency – due to climate change and the flagrant disregard of the environment in the relentless dive to impose imported terms of reference for modernisation and urbanisation. The challenges and strategic importance of realising urban design in South Asia’s contemporary context of borrowed visions, abstract land-use planning and a diminishing political will are, obviously, innumerable. How to qualitatively intervene as an urbanist in such a context? This paper will argue that an understanding of contexts, based on fieldwork, is necessary in order to project feasible urban visions and strategic urban design projects that can make more evident particular sites’ inherent qualities and creatively marry ecological, infrastructural, and urbanisation issues by solutions that cut across multiple scales and sectoral divisions. Interpretative mapping is a first step to transform a territory. An understanding of the context and the reading of sites are necessary in order to create modifications that have logic and relate to the particularities of places and situations. Three scales of mapping (territorial, urban, and tissue) will be presented. The territories/cities investigated are the southwest (Galle-Matara) coast of Sri Lanka, Mumbai, the economic engine of India, and Khulna, the third largest city in Bangladesh.