Engineering: issues, challenges and opportunities for development ...

ENGINEERING: ISSUES CHALLENGES AND OPPORTUNITIES FOR DEVELOPMENTquent dry spells, and higher ET. Flood frequencies are likely toincrease in many areas, although the amount of increase forany given climate scenario is uncertain and impacts will varyamong basins.Water quality problems may increase where there is less flowto dilute contaminants introduced from natural and humansources. The increase in water temperature will alter the rateof operation of bio-geo-chemical processes (degrading andcleaning) and lower the dissolved oxygen concentration ofwater. Similarly, the increased occurrence of higher runoff willincreases the load of pollutants and the overflowing of sewers.Furthermore, increased flooding frequency with overflow oftreated or untreated wastewater sewer systems will seriouslyaffect the biotic life cycle and with a higher possibility of outbreaksof waterborne diseases (such as cryptosporidium presence).The water quality matter may be more sensitive in lakesdue to higher incidence of eutrophication process (Hellmuthand Kabat, 2002). 146The above impacts are in addition to the obvious impacts ofincreased risk of damage to stormwater infrastructure andfacilities (e.g. underground drains, levee banks, pump stationsand so on) due to higher peak flows. There are several otherimpacts, which we can only guess at the moment, such as anincreased risk of pipe failure and collapse due to dry soil conditions.Climate change will affect different cities in different ways withsome experiencing more frequent droughts and water shortagewhile others will have more intense storm events with subsequentflooding issues. Flexible and adaptable solutions arehence required to reduce the vulnerability of cities to thesechanges.Population growth and urbanizationPopulation growth and urbanization will be one of the world’smost important challenges in the next few decades. The UnitedNations population prospects report (2006) 147 illustrates thehigher rate of population growth in urban areas in developingcountries. In less developed countries, urban population willgrow from 1.9 billion in 2000 to 3.9 billion in 2030, averaging2.3 per cent per year. On the other hand, in developed countries,the urban population is expected to increase from 0.9billion in 2000 to 1 billion in 2030, an overall growth rate of 1per cent (Brockerhoff, 2000). 148146 Hellmuth, M. and Kabat, P. 2002. Impacts. In: Appleton, B. (Ed.), Climate changes thewater rules: How water managers can cope with today’s climate variability and tomorrow’sclimate change. Dialogue on Water and Climate, Delft.147 Available at: http://www.un.org/esa/population/unpop.htm (Accessed: 25 May2010).148 Brockerhoff, M. P. 2000. An Urbanizing World. Population Bulletin, A Publication ofPopulation Reference Bureau, Vol.55, No.3, pp.1–45.The numbers and sizes of cities, mostly in developing countries, areincreasing due to the higher rate of urbanization. In 1950, New YorkCity and Tokyo were the only two cities with a population of overten million inhabitants. By 2015, it is expected that there will betwenty-three cities with a population over ten million. Of these,nineteen will be in developing countries. In 2000, there were twentytwocities with a population of between five and ten million; 402cities with a population of one to five million; and 433 cities in the0.5 to one million categories.Almost 180,000 people are added to the world’s urban populationeach day. It is estimated that there are almost a billionpeople in poverty in the world; of which over 750 million livein urban areas without adequate shelters and basic services(UN, 2006). 149 Population growth and rapid urbanization willcreate a severe scarcity of water and will have a tremendousimpact on the natural environment. In order to meet futurewater demand, cities will need to tap their water supply fromsources situated far away from the urban area. Moreover, rapidincreases in built-up areas disturbs the local hydrological cycleand environment by reducing the opportunity for naturalinfiltration (because the absorbing land has been sealed, forexample by road or car parks), producing rapid peak stormwaterflows.Cities in developing countries are already faced with enormousbacklogs in shelter, infrastructure and services as they are confrontedby insufficient water supply, deteriorating sanitationand environmental pollution. Larger populations will demandlarger proportions of water while simultaneously decreasingthe ability of ecosystems to provide more regular and cleanersupplies.Sustaining healthy environments in the urbanized world of thetwenty-first century represents a major challenge for humansettlements, development and management. Again, flexibleand innovative solutions are needed to cope with sudden andsubstantial changes in water demand for people and theirassociated economic activities.Deterioration of infrastructure systemsIn order for the urban water cycle to function effectively, itneeds to be supported by appropriate infrastructure in goodworking condition. Protecting the infrastructure used to treatand transport water (including sources, treatment plants, anddistribution systems) is an important step in ensuring thesafety of drinking water. However, in most cities worldwide,there has been years of neglected maintenance to water storage,treatment, and distribution systems. Poorly maintainedwater supply systems can generally be traced to insufficientfinancial resources and poor management. This deterioration149 Available at: http://www.un.org/esa/population/unpop.htm (Accessed: 25 May2010).286