Change of stream network connectivity and its impact on flood control

AbstUrbanization can alter the hydrogeomorphology of streams and rivers,change stream network structures,and reduce stream network connectivity,which leads to a decrease in the storage capacity of stream networks and aggravates flood damage.Therefore,investigation of the ways in which stream network connectivity impacts flood storage capacity and flood control in urbanized watersheds can provide significant benefits.This study developed a framework to assess stream network connectivity and its impact on flood control.First,a few connectivity indices were adopted to assess longitudinal stream network connectivity.Afterward,the static and dynamic storage capacities of stream networks were evaluated using storage capacity indices and a one-dimensional hydrodynamic model.Finally,the impact of stream network connectivity change on flood control was assessed by investigating the changes in stream network connectivity and storage capacity.This framework was applied to the Qinhuai River Basin,China,where intensive urbanization has occurred in the last few decades.The results show that stream network storage capacity is affected by stream network connectivity.Increasing stream network connectivity enhances stream network storage capacity.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Preparation and gaseous photocatalytic activity of smooth potassium dititanate film

A new smooth potassium dititanate film was prepared by sol-gel method and characterized by thermogravimetry(TG)and differential scanning calorimetry(DSC),X-ray diffraction(XRD),atomic force microscopy(AFM),UV-Visible diffuse reflectance and Raman spectroscopy.The gaseous photocatalytic activity of smooth K_(2)Ti_(2)O_(5)films was studied using contact angle analysis from the photocatalytic decomposition of octadecyltrichlorosilane(OTS)based self-assembled monolayers(SAMs)formed on K_(2)Ti_(2)O_(5)films.The photocurrent response of the film was determined by an electrochemical method.It was shown that the films were smooth,compact,and transparent when formed on glass.Compared with TiO_(2)film,the K_(2)Ti_(2)O_(5)film showed wide absorption in the ultraviolet and visible region.It was found that the monolayers on K_(2)Ti_(2)O_(5)decomposed much faster than those on TiO_(2)under UV irradiation of 254 nm in air.The film also exhibited a stronger photoresponse and a more stable anodic photocurrent.The K_(2)Ti_(2)O_(5)film efficiently decomposes the alkylsiloxane monolayers under UV irradiation in air and it was found to be a good photocatalyst for gaseous organic pollutant treatment.