Development of WEP model and its application to an urban watershed

Abstract

Abstract:A distributed hydrological model, water and energy transfer processes (WEP) model, is developed to simulate spatially variable water and energy processes in watersheds with complex land covers. In the model, state variables include depression storage on land surfaces and canopies, soil moisture content, land surface temperature, groundwater tables and water stages in rivers, etc. The subgrid heterogeneity of land use is also taken into consideration by using the mosaic method. For hydrological processes, evapotranspiration is computed by the Penman-Monteith equation, infiltration excess during heavy rains is simulated by a generalized Green-Ampt model, whereas saturation excess during the remaining periods is obtained by doing balance analysis in unsaturated soil layers. A two-dimensional simulation of multilayered aquifers is performed for groundwater flow. Flow routing is conducted by using the kinematic wave method in a one-dimensional scheme. For energy processes, short-wave radiation is based on observation or deduced from sunshine duration, long-wave radiation is calculated according to temperatures, latent and sensible fluxes are computed by the aerodynamic method and surface temperature is solved by the force-restore method. In addition, anthropogenic components, e.g. water supply, groundwater lift, sewerage drainage and energy consumption, etc. are also taken into account. The model is applied to the Ebi River watershed (27 km 2 ) with a grid size of 50 m and a time step of 1 h. The model is verified through comparisons of simulated river discharges, groundwater levels and land surface temperatures with the observed values. A comparison between water balance at present (1993) and that in the future (2035) is also conducted. It is found that the hydrological cycle in the future can be improved through the implementation of infiltration trenches for the storm water from urban canopies.

Quantitative analysis on the environmental impact of large-scale water transfer project on water resource area in a changing environment

“…The capability of each model can be fully utilized through modularization strategies during the establishment of the comprehensive coupled model. In this study, the related modules of the regional climate-weather research and forecasting (CWRF) model and regional climate model version 3 (RegCM3) are selected for the simulation of atmospheric water circulation and energy process (Liang et al, 2005a(Liang et al, ,b, 2012Yuan and Liang, 2011;Pal et al, 2007); related modules of the water and energy transfer processes (WEP) model are selected for the simulation of natural hydrological cycle (Jia et al, 2001); a water allocation model is used for the simulation of social water circulation (Zhao et al, 2007); related modules of geoprocess (GEOPRO) model, community land model (CLM) and dynamic global vegetation model (DGVM) are selected for the simulation of natural vegetation (Oleson et al, 2004;Steffen et al, 1996); and related modules of DSSAT are selected for crops (Jones et al, 2003). The essential simulation process and characteristics of the selected prototype models are listed in Table 1.…”

Diffusive-Wave Based Hydrologic-Hydraulic Model with Sediment Transport. I: Model Development

“…Examples of the KW and DW models are MIKE SHE (Abbot et al, 1986), WEP (Jia et al, 2001), tRIBS (Ivanov et al, 2004), InHM (Heppner et al, 2006) and other simplified models such as TOPMODEL (Beven and Kyrkby, 1979) or ANSWERS (Beasely et al, 1980). In these models a Strickler / Manning-type law is usually applied for the friction slope calculation or by means of even more simplified assumptions such as making the flow proportional to the bed slope (Beven and Kyrkby, 1979).…”

Applicability of an Improved Water and Energy Transfer Processes Model on Rapid Rainfall-Runoff Events of Tokyo Urban Watersheds

“…Y. Jia et al 1) introduced the WEP model and applied it to the Ebi River watershed (27 km 2 ) for a five-year period. The simulation, however, did not focus on individual rainfall durations when value differences between simulated and observed values at short periods are significant.…”