Quoted from: Demissie, Misganaw, Abiola A. Akanbi, and Abdul Khan. Hydrologic Modeling of Landscape Functions of Wetlands. Illinois State Water Survey, Champaign, Research Report 125, 1997. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.534.3382&rep=rep1&type=pdf 

      Durgunoglu et al. (1987) developed a physically based, distributed-parameter, continuous model called the PACE Watershed Model (PWM) as part of the Precipitation Augmentation for Crops Experiment (PACE) project at the Illinois State Water Survey. The PWM uses daily and hourly data and is applicable for agricultural watersheds of various sizes. The PWM incorporates selected features of three models: ANSWERS, CREAMS, and the Prickett Lonnquist Aquifer Simulation Model (PLASM), a ground-water flow model developed by Prickett and Lonnquist (1971).

      The major components of the PWM are schematically represented in figure 10. The PWM's soil moisture component was obtained from the CREAMS model as a way to use soil, crop, and climatic information in the modeling process. Overland flow and channel flow components were modified from the ANSWERS model, which employs hydraulics equations to simulate these processes. The ground-water flow component of the PWM was based on PLASM, which uses the two-dimensional (X-Y plane) partial differential equation of ground-water motion to model ground-water flow.

Figure 10. Components of the PACE Watershed Model or PWM (after Durgunoglu et al., 1987)