Review on Urban Hydrology

Abstract

Urban hydrology, which officially became an independent subject in the 1980s, is an important branch of hydrology focusing on urban drainage design and other issues of computational hydrological engineering. The advance of global urbanization has meant that both urban hydrology and its associated effects have become increasingly prominent because the hydrological processes of cities have undergone profound change, such that the rain island effect, wet/dry island effect, urban storm-water logging, water pollution, and other water-related events now occur more frequently in urban areas. Urban hydrology must address increasingly complex problems in such rapidly developing areas. Current research on urban hydrology can be divided broadly into two main directions: hydrological effects of urbanization and the simulation of urban hydrological processes. There has been much research on the various aspects of hydrological effects of urbanization, and the mechanism of the rain island effect is relatively well understood. However, research conclusions regarding the urban wet/dry island effect in different regions are inconsistent. Since the second half of the 20th century, research on the water environment has received considerable attention and water-related ecological effects of urbanization have been highlighted, resulting in establishment of water-quality models and theories of urban ecological carrying capacity. Regarding the simulation of urban hydrology, most of the researches are focused on the "natural" aspects of the rainfall-runoff yield in urban areas; while the few researches on the "social" aspect are limited in urban-water-demand forecasting. A quantitative precipitation-evaporation- runoff simulation model has also been established, which includes urban roofs, hardened ground, urban green spaces, and other complex urban surfaces. However, studies on the mechanism of "artificial" water consumption by cities are less comprehensive. Future development of urban hydrology requires a breakthrough with respect to the mechanism of water consumption by cities, in terms of predicting extreme events and simulating urban hydrological responses, and the quantitative assessment and prediction of the hydrological effects of urban cluster development.