Uncontrolled urbanization and the growing population pressure are essential challenges for the water management in urbanized regions of the emerging- and developing countries. In terms of the environment, the reciprocal impact of urban development and groundwater represents one of the most important aspects of growing cities.The interaction between urban development and groundwater may be explained in the relation with the land use pattern and stage of city evolution on affecting the quantity and quality of groundwater (see Figure 1). Quantity and quality changes are caused commonly by the increase of groundwater abstraction and the existing of new sources of recharge Putra 2007). Important previous studies of the effect of fast growing cities on groundwater are given by Foster et al. (1993), Morris et al. (1994) and Vasqeuz-Sune et al. 2005. The main issues concluded from these studies are:
– Urbanized area changes groundwater recharge or cycle, with modification to the existing recharge and the introduction of the new sources
– Discharging of new sources of recharge in urbanized area causes extensive but essentially diffuse groundwater contamination.
– Fluctuations in groundwater levels and
– impact on engineering structure.
It seems that urbanization reduces infiltration to groundwater due to the impermeabilization of the catchment by paved areas, buildings and roads. But recharge beneath cities is usually substantially greater than the pre-urban values (Foster et al. 1993, Lerner 2000). The sources and pathways for groundwater recharge in urban areas are more numerous and complex than in rural environments. The increase of groundwater recharge in urbanized areas is closely related to three main sources: rainwater, wastewater and main leakage from water supply networks. In cities without adequate sewers for waste water transport, as mush as 90 % of abstracted water may return as groundwater recharge (Lerner et al. 1990). In these cities, the most important recharge source would be the infiltration of waste water from large numbers of septic tanks, latrines and soakaways as well as inadequate sewers (Lerner 2002). This is especially relevant for cities that are built atop shallow aquifers and/or for cities being located in a river system. The effect of urban recharge sources will be always significantly larger than precipitation recharge in semi arid and arid regions. But in humid areas, urban recharge may only balance the loss of precipitation recharge caused by the impermeable areas, and the overall effect of urbanization will be small (Lerner et al.1990).
Fast growing cities with an inadequate wastewater system have potentially major effect on increasing groundwater recharge than cities with sewerage system. It can be also concluded that almost all urbanization processes can potentially increase the rate of infiltration to groundwater. The effect of urbanization on the quality of recharge is commonly poor, especially if waste water is an important component.
Good comprehensive reports of the problem of contaminated groundwater in urbanized areas of developed and developing countries can he found on Morris et al. (1994), Lerner et al. (1996), Massone et al. (1998), Chilton (1999), and Wakida et al. (2005). The issue of groundwater contamination of wastewater disposal is a more serious problem in cities of developing countries.
However, it is clear that human activities in urbanized areas threaten the groundwater not only due diffuse contaminant loading from urban recharge system, but also due to many other ways. This means that the different forms of land use such as landfills, urban agriculture, industry and trade as well as diverse residential types with their corresponding wastewater systems influence the emission of pollutants in surface and groundwater, including groundwater recharge (Strohschön et al. 2011).
Also it has to be considered, that the occurrence of contaminants in groundwater does not only depends on the characteristics of contaminant loading as a result of human activity, but also depends on the inherent attenuation capacity of the intervening strata between contaminant source and water table (Morris et al. 2003). This inherent attenuation capacity of the intervening strata depends on its geological, hydrological and hydrogeological condition (Daly et al. 2002).
Chilton, J. (ed.) (1999): Groundwater in the urban environment, International Contributions to Hydrogeology Vol. 21, 342 p, IAH, A.A. Balkema,Rotterdam.
Daly, D., Dassargues, A., Drew, D., Dunne, S., Goldscheider, N., Neale, S., Popescu, I.C., Zwahlen, F. (2002): Main Concepts of the European Approach to Karst Groundwater Vulnerability Assessment and Mapping, Hydrogeology Journal, Vol. 10, p. 340 – 345, Springer-Verlag.
Foster S.S.D., Morris B.L., and Lawrence A.R. (1993): Effects of Urbanization on groundwater recharge, in Wilkinson, W.B., (ed), Groundwater Problems in Urban Areas, Proceeding of Institution of Civil Engineers, June 1993, London, p. 43 – 63.
Lerner D.N. (2000): Guidelines for estimating urban loads of nitrogen to groundwater, Project NT1845, Groundwater Protection and Restoration Group, Dept. Of Civil and Structural Engineering,UniversityofSheffield, Mappin St.
Lerner D.N. (2002): Identifying and quantifying urban recharge: a review, Hydrogeology Journal, Volume 10, p. 143 – 152, Springer-Verlag.
Lerner, D.N., Issar, A.S., and Simmers.I. (1990): Groundwater Recharge: A Guide to Understanding and Estimating Natural Recharge, International Contributions to Hydrogeology Vol. 8, IAH, Verlag Heinz Heise,Hannover,Germany.
Lerner, D.N, and Barret, M.H. (1996): Urban Groundwater Issues in The United Kingdom, Hydrogeology Journal, Vol.4, No.1, p. 80 – 89, Springer-Verlag.
Massone H.E., Martinez D.E., Cionchi J.L., and Bocanegra E. (1998): Suburban areas in developing countries and their relationships to groundwater pollution: A case study of Mar del Pata, Argentina, Environmental Management Journal, p.245 – 254, Springer-Verlag New York Inc.
Morris, B.L., Lawrence, A.R., Chilton, P.J.C., Adams, B., Calow, R.C., and Klinck, B.A. (2003): Groundwater and its susceptibility to degradation: A global assesment of the problem and options for management. Early Warning and Assesment Report Series, RS.03-3. United Nations Environment Programme, Nairobi, Kenya.
Putra, Doni P. E. (2007): The Impact of Urbanization on Groundwater Quality. A Case Study in Yogyakarta City – Indonesia. Mitteilungen zur Ingenieurgeologie und Hydrogeologie 96. Aachen.
Putra, D., Baier, K. (2008): Impact of Urbanization on Groundwater Recharge – The Example of the Indonesian Million City Yogyakarta , In: UN Habitat- United Nations Settlement Programs: Fourth session of the World Urban Forum, Nanjing, China, Documentations of Germany’s Contribution to a Sustainable Urban Future.
Strohschön, R., Azzam, R., Baier, K. (2011): Mega-Urbanization in Guangzhou – Effects on Water Quality and Risks to Human Health , In: Krämer, A. , Khan, M.M.H. , Kraas, F. (Hrsg.): Health in Megacities and Urban Areas (Contributions to Statistics) , Heidelberg , 221 – 229.
Vazquez-Sune, S., Sanchez-Vila, X., and Carrera, J. (2005): Introductory review of specific factors influencing urban groundwater, an emerging branch of hydrogeology, with reference to Barcelona, Spain, Hydrogeology Journal, Volume 13, p.522 – 533, Springer-Verlag.
Wakida, F. T. and Lerner, D.N. (2005): Non-agricultural Sources of Groundwater Nitrate: A Review and Case Study, Water Research, Vol. 39, p. 3 – 16, Elsevier Ltd.