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| . Excerpts from the......Doctoral Thesis...2005....of..
Edgar L. Villarreal.....
Department of Water Resources Engineering ......
Lund Institute of Technology..... Lund University...Sweden
............ Open stormwater drainage systems and urban renewal............
Several ingenious attempts have been developed to mitigate totally or partially problems such as depletion of groundwater levels,...... increase of peak flows and degradation of water courses........ From the point of view of beneficial use of stormwater and integration of stormwater within the built environment..., retention/detention of stormwater by means of open stormwater systems consisting of one or a combination of several BMPs has proven to be of significant importance........ Open stormwater systems,.. such as ponds,.. wetlands,.. green-roofs and open channels,.. can achieve stormwater control while at the same time enhancing wildlife habitats and providing opportunities for recreation...... This approach goes hand in hand with today�s city planning which aims to make visible and enhance the natural environment for people who currently live in an artificial environment (G�ransson, 1994)....... There is also a need for open spaces in our cities: today, much space dedicated to car parking and the area covered by asphalt is several orders of magnitude greater than the space used for recreation and other amenities....... Furthermore,.. those former surfaces,.. which are impermeable,... are more carefully planned and maintained than the latter which are often permeable................... Additional wildlife benefits can be achieved....... According to McGuckin and Brown (1995),.. �landscape integrity could be increased, urban wildlife habitat enhanced and opportunities for residential non-consumptive wildlife recreation improved through integration of the evolving blue-green open space provided by urban stormwater management facilities into existing greenways�.......... The same authors also argued that municipal stormwater management requirements represent an excellent opportunity to incorporate wildlife habitats into evolving urban green corridors.... However,.. few urban stormwater management facilities are actually designed to achieve the broader community and landscape ecological objectives of creating healthy,... aesthetic landscapes that support a richness and diversity of plants and provide passive recreational opportunities.......... Open stormwater management facilities constitute valuable blue-green open space in urbanised environments which,.. if planned properly,.. have the potential to enhance urban wildlife and recreational opportunities through integration with existing green corridors...... The primary objectives of such an approach are consistent with those of... the World Conservation Strategy (Ibid):........................... (1) to maintain essential ecological processes and life support systems; .................................(2) to preserve genetic diversity; .............................(3) to ensure the sustainable utilization of species and ecosystems.
It is recognised that open stormwater systems achieve the following (G�ransson, 1994):
................................1. Landscape architecture functions
- Aesthetics or sensual function: vision,.. sound,.. smell ..and ..tactile impressions ..
- Open space function: creates lively open space.
.......................................2. Pedagogical/ecological functions:.. an open stormwater system makes water visible..... This provides a habitat for plants and animals, while at the same time provides people with proximity to nature
.........................................3. Social functions: water represents a magnetic attraction for people..... People enjoy meeting near bodies of water. All human beings are attracted and positively influenced by water in its different forms...
...........................................4. Technical functions: retention and treatment function.....
In many urban areas,.. planners are working to develop systems of green corridors or linear open spaces along natural or artificial corridors,.. such as riverfronts,.. streams,.. ridgelines,.. abandoned right-of-ways,.. canals or scenic roads ...(Lindsey, 1999)...... Stormwater can be integrated as an element of these green corridors. Many green corridors include trails for active recreational use including walking, bicycling and skating. ........
There are several examples where stormwater has been successfully integrated into urban environments...... They can be as simple as incorporating a water cascade into the drainage system design of a plaza where runoff from small storms is used as a supply source is just one way of turning runoff into an amenity (Roesner, 1999).......The philosophy of urban stormwater management has been changing from draining stormwater as quickly as possible,... to reducing both the force of the flowing water and the concentrations of pollutants carried by runoff,... as well as providing a pleasant urban environment and wildlife habitat..... All these issues imply a multi-disciplinary approach. In the years to come,.. there will still be a challenge in terms of sustainable urban water management:...... to learn from the lessons of the past to recognise that there are many sides to an issue,.... that co-operation can be productive in resolving urban water related problems,... and that scientific understanding of systems is absolutely necessary..........................
The traditional approach to handle stormwater from cities has been to drain it as fast as possible by means of underground culverts............... Thus,.. in urban areas the natural water cycle is influenced by infrastructure that hinders infiltration and concentrates stormwater flows............. This approach has been shown to cause several environmental problems as stormwater from urban areas can be polluted by heavy metals,... organic material,... suspended material and nutrients.......... When discharged to the nearest receiving water,... it affects significantly the local ecology,..... biology,.... ..............................Since the implementation of the first modern sewer systems in the 1800s and until recently,.... the philosophy of stormwater management was to dispose of the water as quickly as possible from cities to the nearest receiving water..... This traditional,... or quick drainage,.. design approach caused not only problems related to the impairment of receiving waters,.. transport of pollutants,.. increased peak flows,.. etc ..(Villarreal, 2003),.. but also denied city dwellers the enjoyment of stormwater in cities... Moreover, sewer systems have several operational problems including combined sewer overflows (CSOs),.. sediments in sewers,.... inflow and infiltration of both stormwater and groundwater,... and discharge of untreated stormwater.......................
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