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HYDROGEOCHEM 4.0 是实用的流体流动、热传递耦合模型，可以通过饱和-非饱和介质的HYDROGEOCHEMical 传输。HYDROGEOCHEM 5.0将模型升级为三维模式。
HYDROGEOCHEM 4.0：通过饱和-不饱和介质的流体流动，热传输和水文地球化学耦合模型
HYDROGEOCHEM 4.0计算机程序是二维的饱和/不饱和多孔介质中水流，热传输，溶质传输和地球化学动力学/平衡反应的耦合模型。
HYDROGEOCHEM 5.0：在可变饱和条件下流体流动，热传输和水化地球化学耦合的三维模型
HYDROGEOCHEM 5.0计算机程序是在饱和/不饱和介质中的流体流动，热传输，水文传输和生物地球化学动力学/平衡反应的数值模型。它是二维HYDROGEOCHEM 4.0的三维版本。
水文地球化学简介
HYDROGEOCHEM的目的是模拟瞬态和/或稳态密度相关的流场和温度分布，并计算地下介质中反应性多种化学浓度的瞬态和/或稳态分布。
HYDROGEOCHEM可以在完全饱和，完全不饱和，部分不饱和或部分饱和的地下介质的三维平面上计算和预测压头，含水量，流速和总压头的分布。它还可以计算和预测多种化学成分的时空分布。介质可以根据需要由具有不同材料属性的多种类型的土壤和地质单元组成。每种土壤类型可以是各向同性或各向异性的。控制化学分布分布的过程包括（1）水络合，还原-氧化，吸附以及沉淀和溶解的地球化学平衡，以及（2）通过对流，分散和不饱和作用的水文输送。
在适当的初始边界条件和四种边界条件的约束下，利用Galerkin有限元方法模拟了控制不饱和介质中压力分布和水流的广义Richards方程和Darcy定律。根据质量守恒原理推导水文输运方程（一组PDE），并基于质量平衡和质量作用推导地球化学平衡方程（一组AE）。PDE和AE的耦合集是使用常规有限元方法或具有峰值捕获方案的混合Langrangian-Eulerian有限元方法来模拟的，这些方法受适当的初始边界条件和四种边界条件的影响。六面体元素，三棱柱，
HYDROGEOCHEM是饱和-不饱和介质中水文传输和地球化学反应的耦合模型。它旨在模拟Na，水成分的瞬态和/或稳态传输以及Ns吸附剂成分和离子交换部位的瞬态和/或稳态质量平衡。HYDROGEOCHEM沿着运输路径计算N组分物种，Mx复杂物种，My吸附物种的物种分布。Mz离子交换物质和Mp可能沉淀的物质。物理，水文和化学设置如下。
介质：非均质和各向异性。
流量条件：饱和-不饱和流量。
水文过程：对流，扩散和扩散。
化学过程：水络合，吸附/解吸（表面络合，恒定电容和双层方法），离子交换，沉淀/溶解，氧化还原和酸碱反应。
源/接收器：时空相关元素和点源/接收器。
初始条件：指定的初始条件或模拟的稳态解作为初始条件。
边界条件：Dirichlet边界上规定的总分析浓度，流入边界上规定的通量，流出边界上的自然推测通量-所有边界值（浓度或通量）在空间上和时间上都是依赖的。
数值离散：具有四边形元素，三角形元素或这两种类型的混合物的有限元方法。
近似选项：矩阵或质量块一致，用于表面和元素积分的节点正交或高斯正交。
求解器：直接带矩阵求解器，基本点迭代和4种PCG方法（多项式PCG，不完全Cholesky PCG，修改的不完全Cholesky PCG和对称连续超松弛PCG）。
时间步长：隐式差异，Crank-Nicholson中心差异或中间差异。
地球化学反应的求解方法：牛顿-拉夫逊全旋转解雅可比矩阵方程式和物种浓度约束。
HYDROGEOCHEM是可用于模拟反应性多物种-多组分化学物质通过饱和-不饱和介质传输的模型。它不是路径模型；它不是路径模型。它是一个真实的运输模型，并伴有均相和异质地球化学反应。
水文地球化学的特殊功能
HYDROGEOCHEM的特殊之处在于它在建模方面的灵活性和多功能性，从而解决了尽可能多的问题。该模型旨在（1）处理异质和各向异性介质，（2）考虑时空分布以及点源/汇，（3）接受规定的初始条件或通过模拟稳态版本获得初始条件（4）处理分布在Dirichlet边界上的规定瞬态浓度，（5）处理可变边界上的时间相关通量，（6）处理Cauchy边界上的时间相关总通量，
水文化学输入
（1）就节点和元素而言的几何形状，以及就节点和片段而言的边界；（2）土壤特性，包括：（a）饱和水力传导率或渗透率；（b）水和介质的可压缩性；（c）堆密度；（d）每种土壤或地质单位的三种土壤特性曲线，即保留曲线，相对电导率与水头曲线以及水容量曲线；（e）影响孔隙率；（f）每种土壤类型或地质单位的分散度和有效分子扩散系数；（3）压头在感兴趣区域的初始分布；（4）净降水量，允许的积水深度，潜在的蒸发以及允许的土壤小压头；（5）在狄利克雷边界上的规定头；（6）在柯西和/或诺伊曼边界上的规定通量；（七）人工取水或注水；（8）化学成分数目，化学种类及其热力学数据库；（9）人工水/水和所有化学成分的水槽；（10）在狄利克雷边界上规定的所有化学成分的总浓度；（11）在可变边界上规定的所有化学成分的通量；（12）所有化学成分浓度的初始分布。项目4到11中的所有输入都可以是时间相关的或随时间变化的。（11）在可变边界上规定的所有化学成分的通量；（12）所有化学成分浓度的初始分布。项目4到11中的所有输入都可以是时间相关的或随时间变化的。（11）在可变边界上规定的所有化学成分的通量；（12）所有化学成分浓度的初始分布。项目4到11中的所有输入都可以是时间相关的或随时间变化的。
水文化学输出
（1）在任何期望的时间在二维网格上的压头，总压头，含水量和流速；（2）在任何需要的时间通过各种边界的水通量和介质中积累的水量；（3）在任何需要的时间在三维网格上分布所有化学成分的总分析浓度，总溶解浓度，总吸附浓度，总沉淀浓度和自由离子浓度；（4）通过可变边界的废物通量；（5）等效kds作为感兴趣区域中时间和空间的函数。
HYDROGEOCHEM要求：具有16 MB RAM和FORTRAN编译器的Pentium，任何工作站，例如IBM RS6000，DEC Alpha，Silicon Graphics，Sun SparcStation和HP 9000系列。
【英文介绍】
HYDROGEOCHEM 4.0:
A Coupled Model of Fluid Flow, Thermal Transport, and HYDROGEOCHEMical Transport through Saturated-Unsaturated Media
The computer program HYDROGEOCHEM 4.0 is a coupled model of water flow, thermal transport, solute transport, and geochemical kinetic/equilibrium reactions in saturated/unsaturated porous media in two dimensions.
HYDROGEOCHEM 5.0:
A Three-Dimensional Model of Coupled Fluid Flow, Thermal Transport, and HYDROGEOCHEMical Transport through Variably Saturated Conditions
The computer program HYDROGEOCHEM 5.0 is a numerical model of fluid flow, thermal transport, hydrologic transport, and biogeochemical kinetic/equilibrium reactions in saturated/unsaturated media. It is a three-dimensional version of the two-dimensional HYDROGEOCHEM 4.0.
INTRODUCTION TO HYDROGEOCHEM
The purpose of HYDROGEOCHEM is to simulate transient and/or steady-state density-dependent flow fields and temperature distribution and to compute transient and/or steady-state distribution of reactive multispecies chemical concentrations in subsurface media.
HYDROGEOCHEM computes and predicts the distribution of pressure head, moisture content, flow velocity, and total head over a three-dimensional plane in either completely saturated, completely unsaturated, partially unsaturated, or partially saturated subsurface media. It also computes and predicts the spatial-temporal distribution of multi-chemical components. The media may consist of as many types of soils and geologic units as desired with different material properties. Each soil type may be isotropic or anisotropic. The processes governing the distribution of chemical distribution include (1) geochemical equilibrium of aqueous complexation, reduction-oxidation, sorption, and precipitation and dissolution, and (2) hydrological transport by flow advection, dispersion, and effect of unsaturation.
The generalized Richards' equation and Darcy's law governing pressure distribution and water flow in saturated-unsaturated media are simulated with the Galerkin finite-element method subject to appropriate initial and four types of boundary conditions. The hydrological transport equations (a set of PDEs) are derived based on the principle of conservation of mass, and the geochemical equilibrium equations (a set of AEs) are derived based on the mass balance and mass action. The coupled set of PDEs and AEs are simulated with either the conventional finite-element methods or the hybrid Langrangian-Eulerian finite-element method with peak capturing scheme subject to appropriate initial and four types of boundary conditions. Hexahedral elements, triangular prism, and tetrahedral elements are used to facilitate the discretization of the region of interest.
HYDROGEOCHEMis a coupled model of hydrologic transport and geochemical reaction in saturated-unsaturated media. It is designed to simulate transient and/or steady-state transport of Na, aqueous components and transient and/or steady-state mass balance of Ns adsorbent components and ion-exchange sites. Along the transport path, HYDROGEOCHEM computes the species distribution of N componentspecies, Mx complexed species, My adsorbed species. Mz ion-exchanged species, and Mp potentially precipitated species. The physical, hydrological and chemical settings are as follows.
Media:Heterogeneous and Anisotropic.
Flow Conditions:Saturated-Unsaturated Flows.
Hydrologic Processes:Advection, Dispersion and Diffusion.
Chemical Processes:Aqueous Complexation, Adsorption/Desorption (Surface Complexation, Constant Capacitance, and Double Layer Approaches), Ion-Exchange, Precipitation/Dissolution, Redox, and Acid-Base Reactions.
Source/Sink:Spatially- and Temporally-Dependent Element and Point Sources/Sinks.
Initial Conditions:Prescribed Initial Condition or the Simulated Steady-State Solution as the Initial Condition.
Boundary Conditions:Prescribed Total Analytical Concentrations on Dirichlet Boundaries, Prescribed Fluxes on Flow-In Boundaries, Natural Advective Fluxes on Flow-Out Boundaries - All Boundary Values (Concentrations or Fluxes) are Spatially- and Temporally-Dependent.
Numerical Discretization:Finite-Element Methods with Quadrilateral Elements, Triangular Elements, or the Mixtures of These Two Types.
Approximation Options:Consistent Matrix or Mass Lumping, Nodal Quadrature or Gaussian Quadrature for Surface and Element Integrations.
Solvers:Direct Band Matrix Solver, Basic Point Iterations, and 4 PCG Methods (polynomial PCG, Incomplete Cholesky PCG, Modified Incomplete Cholesky PCG, and Symmetric Successive Over-Relaxation PCG).
Time Stepping:Implicit Difference, Crank-Nicholson Central Difference, or Mid-Difference.
Solution Methods for Geochemical Reactions:Newton-Raphson with Full Pivoting to Solve the Jacobian Matrix Equation and Constraints on Species Concentrations.
HYDROGEOCHEM is the only commercially-available model for the simulation of reactive multispecies-multicomponent chemical transport through saturated-unsaturated media. It is not a path model; it is a true transport model coupled with homogeneous and heterogeneous geochemical reactions.
HYDROGEOCHEM SPECIAL FEATURES
The special features of HYDROGEOCHEM are its flexibility and versatility in modeling as wide a range of problems as possible. The model is designed to (1) treat heterogeneous and anisotropic media, (2) consider spatially and temporally-distributed as well as point sources/sinks, (3) accept the prescribed initial conditions or obtain initial conditions by simulating the steady-state version of the system under consideration, (4) deal with prescribed transient concentrations distributed over a Dirichlet boundary, (5) handle time-dependent fluxes over variable boundaries, (6) deal with time-dependent total fluxes over Cauchy boundaries, (7) include the off-diagonal dispersion coefficient tensor components in the governing equation for dealing with cases when the coordinate system does not coincide with the principal directions of the dispersion coefficient tensor, (8) provide two options for treating the mass matrix - consistent and lumping, (9) give three options (exact relaxation, under- and over-relaxation) for estimating the nonlinear matrix, (10) include two options (direct solution with Gaussian elimination method and successive point iterations) for solving the linearized matrix equations, (11) include both quadrilateral and triangular elements to facilitate the discretization of the region, (12) automatically reset time step size when boundary conditions or sources/sinks change abruptly, and (13) include simultaneous chemical processes of aqueous complexation, precipitation/dissolution, adsorption, ion exchange, redox, and acid-base reactions.
HYDROGEOCHEM INPUT
(1) Geometry in terms of nodes and elements, and boundaries in terms of nodes and segments; (2) soil properties including (a) saturated hydraulic conductivities or permeabilities; (b) compressibility of water and the media, respectively; (c) bulk density; (d) three soil characteristic curves for each type of soil or geologic unit which are the retention curve, relative conductivity vs head curve, and water capacity curve; (e) effect porosity; and (f) dispersivities, and effective molecular diffusion coefficient for each soil type or geologic unit; (3) initial distribution of pressure head over the region of interest; (4) net precipitation, allowed ponding depth, potential evaporation, and allowed minimum pressure head in the soil; (5) prescribed head on Dirichlet boundaries; (6) prescribed fluxes on Cauchy and/or Neumann boundaries; (7) artificial withdrawals or injections of water; (8) number of chemical components as well as chemical species and their thermodynamic data base; (9) artificial sources/sinks of water and all chemical components; (10) prescribed total concentrations of all chemical components on Dirichlet boundaries; (11) prescribed fluxes of all chemical components on variable boundaries; and (12) initial distribution of all chemical component concentrations. All inputs in items 4 through 11 can be time-dependent or constant with time.
HYDROGEOCHEM OUTPUT
(1) pressure head, total head, moisture content, and flow velocity over the two-dimensional grid at any desired time; (2) water fluxes through all types of boundaries and amount of water accumulated in the media at any desired time; (3) distribution of total analytical concentrations, total dissolved concentrations, total sorbed concentrations, total precipitated concentrations, and free ion concentrations of all chemical components over a three-dimensional grid at any desired time; (4) amount of waste fluxes through the variable boundary; and (5) equivalent kds as a function of time and space in the region of interest.
HYDROGEOCHEM Requirements:Pentium with 16 MB RAM and FORTRAN Compiler, any Workstation, e.g., IBM RS6000, DEC Alpha, Silicon Graphics, Sun SparcStation, and HP 9000 Series.
