Since historical times, natural ecosystems such as forests and wetlands are known to regulate water flow and maintain water quality. The past half a century however has witnessed unplanned and rapid development with widespread ecosystem degradation. Meanwhile water treatment and supply happens on an ad hoc basis that is neither sustainable nor affordable for most communities. The revival of an ecohydrological approach is called for, with increased use of ecosystem services in water resources management. The affordable and sustainable aspects of this approach make it especially pertinent for developing countries, given the increasing challenges posed by mounting population, consumption, and climate change. This chapter describes the general links between different ecosystems, hydrology, and water quality and outlines the steps in developing an ecohydrological approach. The next chapter describes case studies that have successfully incorporated an ecohydrological approach in different realms of water resources management in the developing world.
