title: Stream discharge characteristics through urbanization gradient in Danshui River, Taiwan: perspectives from observation and simulation.
abstract: Urbanization and the subsequent changes in land use/cover inevitably influence the quality and even the quantity of stream water. This issue is widely studied through evaluations on land-use change scenarios or comparisons among historical patterns at the same watershed. However, observational stream discharge changes through urbanization gradient have rarely been discussed. In this study, we analyzed 5-year discharge data from 13 gauges in the Danshui River network with a wide range of urbanization gradient to explore the impacts on observational hydrological characteristics in individual catchments. The results reveal that stream discharge in pristine watersheds is characterized by a larger proportion of baseflow and is less fluctuating. When the forest coverage is <90%, the discharge fluctuation almost doubles. Meanwhile, the baseflow fraction decreases gradually with the increase of paddy area, which may concomitantly result from the increasing irrigation. Such a drop in baseflow may threaten the maintenance of the minimum flow required for the stream aquatic ecosystem. Furthermore, we simulated the stream discharges by TOPMODEL with blind land-use-independent parameters. The results show that the simulated discharges are satisfactory, particularly for the pristine catchments, but not as fitting for the paddy-intensive watersheds perhaps due to the unexpected irrigation. On the whole, the calibrated parameters are dependent with the landscape characteristics. The landscape-based parameter estimations can be applied to simulate discharge well, meaning the potential to assess the ungauged watersheds.
authors.affiliation: Department of Geography, National Taiwan University, Taipei, Taiwan. riverhuang@ntu.edu.tw
authors.forename: Jr-Chuan
authors.initials: JC
authors.lastname: Huang
authors.forename: Chun-Chiang
authors.initials: CC
authors.lastname: Lin
authors.forename: Shih-Chien
authors.initials: SC
authors.lastname: Chan
authors.forename: Tsung-Yu
authors.initials: TY
authors.lastname: Lee
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Hsu
authors.forename: Cheing-Tung
authors.initials: CT
authors.lastname: Lee
authors.forename: Jiun-Chuan
authors.initials: JC
authors.lastname: Lin
mesh_terms: D004784:Environmental Monitoring; D008956:Models, Chemical; D045483:Rivers / Q000737:chemistry*; D013624:Taiwan; D014507:Urbanization; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data
chemical_list: D014874:Water Pollutants, Chemical