MM5 model has the main functions of non static dynamic frame, multi-layer grid nesting, various physical process options, four-dimensional variation, and more extensive computer platform transplantation. The simulation area of MM5 adopts Lambert projection, and the two true latitudes are 25 degrees north latitude and 40 degrees north latitude respectively. In order to ensure the accuracy of boundary meteorological field, MM5 simulation area has three grids more than the horizontal boundaries of air quality simulation area; the top of the simulation layer is 100MB, which is vertically divided into the following 23 σ layers. The data of terrain and surface type are global data of USGS; the objective analysis is based on the ADP global surface and high-altitude observation data of NCEP to conduct grid four-dimensional data assimilation. The parameterization of physical processes in the simulation domain are as follows: Kain Fritsch's cumulus parameterization scheme; pleim Xu's boundary layer and land surface parameterization scheme; Reisner's multiphase explicit water vapor scheme; cloud radiation parameterization method; and multi-layer soil model.

High resolution land data assimilation system (hrldas) is an off-line driving force of land surface model existing in weather research and prediction (WRF) model. Hrldas uses a combination of observational and analytical measurements (precipitation, solar and longwave radiation, and surface wind, humidity, and temperature) to drive land surface models to simulate the evolution of land surface conditions (e.g., soil moisture and temperature, snow, etc.). The system has been developed and can run on the WRF domain or multiple site locations.

Ecohat system is based on the study of eco hydrological process mechanism, starting from the basic water cycle process, adding nutrient migration and transformation process in the water cycle process, comprehensively considering the interaction of vegetation / biological growth, water cycle elements and nutrients in land water ecosystem. The ecohat system model is built on the basis of integrating the advantages of eco hydrological process models with physical and chemical mechanisms at home and abroad. After model adjustment, the model adopts parameters suitable for China's natural conditions to establish a localized database. Ecohat system realizes pixel based model operation by inputting regional spatial grid parameters. Therefore, ecohat system is a completely distributed integrated simulation system of eco hydrological process. Ecohat system includes four parts: water cycle, nutrient cycle, plant growth and aquatic environment response. Water cycle is the core of the system and runs through the other three parts. The simulation of water cycle in ecohat system includes five processes: rainfall infiltration, surface runoff, evapotranspiration, root water absorption and soil moisture; nutrient cycle mainly includes the simulation of nitrification, denitrification and ammonia volatilization in soil, the simulation of base cation cycle in soil, and the quantitative simulation of adsorbed phosphorus produced by soil erosion process; plant growth It includes vegetation ecological water use simulation, vegetation NPP (net primary productivity) simulation, productivity distribution process simulation and vegetation nutrient element absorption simulation.

Delft3D is a powerful software package developed by WL Delft hydraulics of Delft University in the Netherlands, which is mainly used in free surface water environment. The software has a flexible framework, which can simulate two-dimensional and three-dimensional flow, wave, water quality, ecology, sediment transport and bed topography, as well as the interaction among various processes. It is one of the most advanced hydrodynamic water quality models in the world. Delft3D system is widely used in the world, such as the Netherlands, Poland, Germany, Australia, the United States and so on, especially the United States has a long history of application. The Delft3D system has been used in Hong Kong since the mid-1970s and has become a standard product of the Hong Kong Environment Agency. Delft3D has been applied more and more in mainland China since the mid 80s, such as Changjiang Estuary, Hangzhou Bay, Bohai Bay, Taihu and Dianchi. Delft3D is the most advanced and complete 3D hydrodynamic water quality model system in the world, especially the unique support surface format.

PMF model is a mathematical receptor model developed by scientists from the U.S. Environmental Protection Agency. It provides scientific support for the development and review of air and water quality standards, exploration research and environmental evidence collection. PMF model can analyze a wide range of environmental sample data: sediment, wet deposition, surface water, ambient air and indoor air.

Distributed hydrological model, water and energy prediction, geotop can be applied to very complex terrain, and integrates all surface energy balance conditions except water balance. For saturated and unsaturated subsurface flow, 3D Richard equation is adopted to realize accurate input of radiation parameters to obtain surface temperature.

Simulating the change of alluvial channel in drought