#ifndef CFE_CFE_H

#define CFE_CFE_H

#include <stdio.h>

#include <math.h>

#include <stdlib.h>

#include <float.h>

#include <string.h>

#define TRUE 1

#define FALSE 0

#define MAX_NUM_GIUH_ORDINATES 10

#define MAX_NUM_NASH_CASCADE 3

#define MAX_NUM_RAIN_DATA 720

// t-shirt approximation of the hydrologic routing funtionality of the National Water Model v 1.2, 2.0, and 2.1

// This code was developed to test the hypothesis that the National Water Model runoff generation, vadose zone

// dynamics, and conceptual groundwater model can be greatly simplified by acknowledging that it is truly a

// conceptual model. The hypothesis is supported by a number of observations made during a 2017-2018 deep dive

// into the NWM code. Thesed are:

//

// 1. Rainfall/throughfall/melt partitioning in the NWM is based on a simple curve-number like approach that

// was developed by Schaake et al. (1996) and which is very similar to the Probability Distributed Moisture (PDM)

// function by Moore, 1985. The Schaake function is a single valued function of soil moisture deficit,

// predicts 100% runoff when the soil is saturated, like the curve-number method, and is fundamentally simple.

// 2. Run-on infiltration is strictly not calculated. Overland flow routing applies the Schaake function repeatedly

// to predict this phenomenon, which violates the underlying assumption of the PDM method that only rainfall

// inputs affect soil moisture.

// 3. The water-content based Richards' equation, applied using a coarse-discretization, can be replaced with a simple

// conceptual reservoir because it never allows saturation or infiltration-excess runoff unless deactivated by

// assuming no-flow lower boundary condition. Since this form of Richards' equation cannot simulate heterogeneous

// soil layers, it can be replaced with a conceptual reservoir.

// 4. The lateral flow routing function in the NWM is purely conceptual. It is activated whenever the soil water

// content in one or more of the four Richards-equation discretizations reaches the wilting point water content.

// This activation threshold is physically unrealistic, because in most soils lateral subsurface flow is not

// active until pore water pressures become positive at some point in the soil profile. Furthermore, the lateral

// flow hydraulic conductivity is assumed to be the vertical hydraulic conductivity multiplied by a calibration

// factor "LKSATFAC" which is allowed to vary between 10 and 10,000 during calibration, resulting in an anisotropy

// ratio that varies over the same range, without correlation with physiographic characteristics or other support.

//

// This code implements these assumptions using pure conceptualizations. The formulation consists of the following:

//

// 1. Rainfall is partitioned into direct runoff and soil moisture using the Schaake function.

// 2. Rainfall that becomes direct runoff is routed to the catchment outlet using a geomorphological instantanteous

// unit hydrograph (GIUH) approach, eliminating the 250 m NWM routing grid, and the incorrect use of the Schaake

// function to simulate run-on infiltration.

// 3. Water partitioned by the Schaake function to be soil moisture is placed into a conceptual linear reservoir

// that consists of two outlets that apply a minimum storage activation threshold. This activation threshold

// is identical for both outlets, and is based on an integral solution of the storage in the soil assuming

// Clapp-Hornberger parameters equal to those used in the NWM to determine that storage corresponding to a

// soil water content 0.5 m above the soil column bottom that produces a soil suction head equal to -1/3 atm,

// which is a commonly applied assumption used to estimate the field capacity water content.

// The first outlet calculates vertical percolation of water to deep groundwater using the saturated hydraulic

// conductivity of the soil multiplied by the NWM "slope" parameter, which when 1.0 indicates free drainage and

// when 0.0 indicates a no-flow lower boundary condition. The second outlet is used to calculate the flux to

// the soil lateral flow path, using a conceptual LKSATFAC-like calibration parameter.

// 4. The lateral flow is routed to the catchment outlet using a Nash-cascade of reservoirs to produce a mass-

// conserving delayed response, and elminates the need for the 250 m lateral flow routing grid.

// 5. The groundwater contribution to base flow is modeled using either (a) an exponential nonlinear reservoir

// identical to the one in the NWM formulation, or (b) a nonlinear reservoir forumulation, which can also be

// made linear by assuming an exponent value equal to 1.0.

//

// This code was written entirely by Fred L. Ogden, May 22-24, 2020, in the service of the NOAA-NWS Office of Water

// Prediction, in Tuscaloosa, Alabama.

// define data structures

//--------------------------

struct conceptual_reservoir

{

// this data structure describes a nonlinear reservoir having two outlets, one primary with an activation

// threshold that may be zero, and a secondary outlet with a threshold that may be zero

// this will also simulate a linear reservoir by setting the exponent parameter to 1.0 iff is_exponential==FALSE

// iff is_exponential==TRUE, then it uses the exponential discharge function from the NWM V2.0 forumulation

// as the primary discharge with a zero threshold, and does not calculate a secondary discharge.

//--------------------------------------------------------------------------------------------------

int is_exponential; // set this true TRUE to use the exponential form of the discharge equation

double storage_max_m; // maximum storage in this reservoir

double storage_m; // state variable.

double coeff_primary; // the primary outlet

double exponent_primary;

double storage_threshold_primary_m;

double storage_threshold_secondary_m;

double coeff_secondary;

double exponent_secondary;

};

struct NWM_soil_parameters

{

// using same variable names as used in NWM. <sorry>

double smcmax; // effective porosity [V/V]

double wltsmc; // wilting point soil moisture content [V/V]

double satdk; // saturated hydraulic conductivity [m s-1]

double satpsi; // saturated capillary head [m]

double bb; // beta exponent on Clapp-Hornberger (1978) soil water relations [-]

double mult; // the multiplier applied to satdk to route water rapidly downslope

double slop; // this factor (0-1) modifies the gradient of the hydraulic head at the soil bottom. 0=no-flow.

double D; // soil depth [m]

double wilting_point_m;

};

struct evapotranspiration_structure {

double potential_et_m_per_s;

double potential_et_m_per_timestep;

double reduced_potential_et_m_per_timestep;

double actual_et_from_rain_m_per_timestep;

double actual_et_from_soil_m_per_timestep;

double actual_et_m_per_timestep;

};

typedef struct evapotranspiration_structure evapotranspiration_structure;

struct massbal

{

double volstart ;

double vol_runoff ;

double vol_infilt ;

double vol_out_giuh ;

double vol_end_giuh ;

double vol_to_gw ;

double vol_in_gw_start ;

double vol_in_gw_end ;

double vol_from_gw ;

double vol_in_nash ;

double vol_in_nash_end ; // note the nash cascade is empty at start of simulation.

double vol_out_nash ;

double vol_soil_start ;

double vol_to_soil ;

double vol_soil_to_lat_flow;

double vol_soil_to_gw ; // this should equal vol_to_gw

double vol_soil_end ;

double vol_et_from_soil ;

double vol_et_from_rain ;

double vol_et_to_atm ;

double volin ;

double volout ;

double volend ;

};

typedef struct massbal massbal;

// define data types

//--------------------------

typedef enum {Schaake, Xinanjiang} surface_water_partition_type;

/* xinanjiang_dev*/

struct direct_runoff_parameters_structure{

surface_water_partition_type surface_partitioning_scheme;

double Schaake_adjusted_magic_constant_by_soil_type;

double a_Xinanjiang_inflection_point_parameter;

double b_Xinanjiang_shape_parameter;

double x_Xinanjiang_shape_parameter;

};

typedef struct direct_runoff_parameters_structure direct_runoff_parameters_structure;

// function prototypes

// --------------------------------

extern void Schaake_partitioning_scheme(double dt, double magic_number, double deficit, double qinsur,

double *runsrf, double *pddum);

// xinanjiang_dev: XinJiang function written by Rachel adapted by Jmframe and FLO,

extern void Xinanjiang_partitioning_scheme(double water_input_depth_m, double field_capacity_m,

double max_soil_moisture_storage_m, double column_total_soil_water_m,

struct direct_runoff_parameters_structure *parms,

double *surface_runoff_depth_m, double *infiltration_depth_m);

extern void conceptual_reservoir_flux_calc(struct conceptual_reservoir *da_reservoir,

double *primary_flux_m, double *secondary_flux_m);

extern double convolution_integral(double runoff_m, int num_giuh_ordinates,

double *giuh_ordinates, double *runoff_queue_m_per_timestep);

extern double nash_cascade(double flux_lat_m,int num_lateral_flow_nash_reservoirs,

double K_nash,double *nash_storage_arr);

extern void et_from_rainfall(double *timestep_rainfall_input_m, struct evapotranspiration_structure *et_struct);

extern void et_from_soil(struct conceptual_reservoir *soil_res, struct evapotranspiration_structure *et_struct, struct NWM_soil_parameters *soil_parms);

extern int is_fabs_less_than_epsilon(double a,double epsilon);

extern void cfe(

double *soil_reservoir_storage_deficit_m_ptr,

struct NWM_soil_parameters NWM_soil_params_struct,

struct conceptual_reservoir *soil_reservoir_struct,

double timestep_h,

/* xinanjiang_dev: since we are doing the option for Schaake and XinJiang,

instead of passing in the constants

pass in a structure with the constants for both subroutines.

//double Schaake_adjusted_magic_constant_by_soil_type,*/

struct direct_runoff_parameters_structure direct_runoff_param_struct,

double timestep_rainfall_input_m,

/* xinanjiang_dev:

double *Schaake_output_runoff_m_ptr,*/

double *flux_output_direct_runoff_m,

double *infiltration_depth_m_ptr,

double *flux_perc_m_ptr,

double *flux_lat_m_ptr,

double *gw_reservoir_storage_deficit_m_ptr,

struct conceptual_reservoir *gw_reservoir_struct,

double *flux_from_deep_gw_to_chan_m_ptr,

double *giuh_runoff_m_ptr,

int num_giuh_ordinates,

double *giuh_ordinates_arr,

double *runoff_queue_m_per_timestep_arr,

double *nash_lateral_runoff_m_ptr,

int num_lateral_flow_nash_reservoirs,

double K_nash,

double *nash_storage_arr,

struct evapotranspiration_structure *evap_struct,

double *Qout_m_ptr,

struct massbal *massbal_struct,

double time_step_size

);

#endif //CFE_CFE_H