关 键 字(英文)：eucalyptus plantations Topog modelling wetness index Leizhou Peninsula
摘 要(英文)：Many hydrological characteristics of a catchment can be inferred from its topography. The eco-hydrological model, Topog,
uses a sophisticated analysis of topography to describe the hydrological characteristics of a catchment in detail. This paper describes an integrated terrain analysis and steady state hydrological modelling study of a small forest catchment on Leizhou Peninsula, southern
China using Topog. The terrain analysis was based on a DEM (digital elevation model) of the central part of the peninsula including
the upper valley of the Nandu River. The basic hydrologic characteristics defining the Jijia catchment were catchment
boundary, high points and saddles, calculated ridges and streams, and an element network separating the catchment into a large number
of relatively uniform units for modelling. The topographic attributes of each element were calculated automatically, including
slope, aspect, upslope contributing area and potential incident solar radiation. The slope of the catchment was relatively low: the
difference between slopes of most elements was in the range of 2.8~5.7 degree, or less than 2.8 degree. The general description of the
Jijia catchment provided by Topog included total catchment area of 0.63 km2 and average amount of incident radiation of 44, 25, and
34 MJ·m-2·d-1 for summer, winter and equinoxes, respectively. The catchment convergence index and steady-state wetness indices
(WI) of the elements of the Jijia experimental catchment with and without solar radiation-weighting were also obtained. From
steady-state drainage flux modelling, we obtained a distribution of WI across the catchment. By setting different parameter values of
uniform drainage flux, the mapped simulations of WI over the catchment indicated that the bigger the uniform drainage flux was, the
higher the WI would be.We modelled a radiation-weighted drainage index at different values of uniform transmissivity (T), different
shaded soil fraction (Es), and different uniform rainfall (R). The result illustrated that the mapped distribution of WI varies as a consequence
of these different data inputs. The distribution of WI was strongly affected by T values which indicated that soil wetness
within some stream zones might extend more widely, given a bigger T value. Conversely, lower values of T resulted in more uniform
spatial distribution of WI over the catchment. Modelled results also varied with shaded fraction, which indicated that a small increase
in solar radiation would result in spatially different distribution of soil moisture content over the catchment. Finally, we made a comparison between a set of uniform rainfall values and found that Topog predicted the expected trend that soil moisture within the
catchment increased with increasing uniform rainfall values.
雷州桉树人工林小集水区地形分析与静态水文学模拟(英文)