地理大数据挖掘——“水-能源-粮食”纽带研究的新机遇

Since the Bonn 2011 conference,the“water-energy-food”(WEF)nexus has aroused global concern to promote sustainable development.The WEF nexus is a complex,dynamic,and open system containing interrelated and interdependent elements.However,the nexus studies have mainly focused on natural elements based on massive earth observation data.Human elements(e.g.,society,economy,politics,culture)are described insufficiently,because traditional earth observation technologies cannot effectively perceive socioeconomic characteristics,especially human feelings,emotions,and experiences.Thus,it is difficult to simulate the complex WEF nexus.With the development of earth observation sensor technologies and human activity perception methods,geographical big data covering both human activities and natural elements offers a new opportunity for in-depth WEF nexus analysis.This study proposes a five-step framework by leveraging geographical big data mining to dig for the hidden value in the data of various natural and human elements.This framework can enable a thorough and comprehensive analysis of the WEF nexus.Some application examples of the framework,major challenges,and possible solutions are discussed.Geographical big data mining is a promising approach to enhance the analysis of the WEF nexus,strengthen the coordinated management of resources and sectors,and facilitate the progress toward sustainable development.

Runoff-and erosion-reducing effects of vegetation on the loess hillslopes of China under concentrated flow

Evaluating the effects of revegetation on runoff and erosion reduction is essential for studying soil and water conservation on the Loess Plateau after implementation of China's Grain for Green Project.However,quantifying the influence of revegetation on the erosion caused by concentrated runoff in extreme rainstorms is still challenging.To evaluate this influence,scouring-erosion experiments were implemented in situ on the vegetated hillslope plots(GR)and bare hillslope plots(CK).The runoffreducing effects of grass(GRR)averaged 31%,20%and 8%,and the erosion-reducing effects of grass(GER)averaged 93%,95%and 93%on the 5-plots,10-plots and 18-plots,respectively.The ratios of GRR to GER were 0.09e0.33,implying that the ability of vegetation to reduce erosion was greater than its ability to reduce runoff.The GRR and GER obviously decreased as the inflow rate increased,and the GRR decreased as the hillslope gradient increased,but there were no obvious differences in the GER between hillslope gradients.Vegetation could decrease the ability of the concentrated flow to carry and transport sediment and increase the energy consumption of the concentrated flow in response to hydraulic resistance.Vegetation also significantly reduced the degree of rill development.The degree of rill dissection on the GR(0.054e0.087 m^(2)m^(2))was lower than that on the CK(0.061e0.184 m^(2)m^(2)).Our findings provide an essential reference for ecological environment and vegetation restoration on loess hillslopes.