Water flow and preferential flow: A State-of-the-Art throughout the literature

Abstract. Studies dealing with water flow and preferential flow are of typically importance because there are still many unresolved water security and scarcity problems. It may indeed be a valuable idea to provide a special review of the progress in the water flow and preferential flow for the applied water science community and to identify what is still missing or unresolved to improve predictions of surface water and groundwater quality within multiscale. This paper aims to review the state of the art on water flow and preferential flow published per year from 1995 to 2015, respectively, and to present a discussion of perspectives and some significant advances in the main themes of water flow and preferential flow that have emerged in recent years, with insights, some promising areas for future work, and suggestions also being provided regarding potential research trends, requirements and solutions. Recorded reports show that it is of general interest in water flow in the period 1995–2015 and also there are clear significant trends from physical hydrology and socio-hydrology perspectives. The future trend of water flow which is predicted in some way indicates a general increase. The term of preferential flow, its significance and progress in the period 1995–2015, shows that despite the increasing number of papers published on preferential flow, there has not been as much attention paid to this topic as we have expected, given its vital role in soil hydrology, water sustainability, slope stability and agricultural management. Finally, existing love-hate relationship between water flow and preferential flow pathways is reviewed.