Landuse.hpp

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// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2026 Caleb Buahin
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

 
#ifndef OPENSWMM_LANDUSE_HPP
#define OPENSWMM_LANDUSE_HPP
 
#include <vector>
 
namespace openswmm {
 
struct SimulationContext;
 
namespace landuse {
 
// ============================================================================
// Buildup/washoff function types
// ============================================================================
 
enum class BuildupType : int {
    NONE     = 0,
    POWER    = 1,
    EXPON    = 2,
    SATUR    = 3,
    EXTERNAL = 4
};
 
enum class WashoffType : int {
    NONE    = 0,
    EXPON   = 1,
    RATING  = 2,
    EMC     = 3
};
 
// ============================================================================
// Per (landuse × pollutant) buildup/washoff parameters — SoA
// ============================================================================
 
struct BuildupParams {
    BuildupType type = BuildupType::NONE;
    double coeff[3] = {};     
    double max_days = 0.0;    
    int    normalizer = 0;    
};
 
struct WashoffParams {
    WashoffType type = WashoffType::NONE;
    double coeff = 0.0;       
    double expon = 0.0;       
    double sweep_effic = 0.0; 
    double bmp_effic = 0.0;   
};
 
// ============================================================================
// Surface quality SoA (per subcatchment × pollutant)
// ============================================================================
 
struct SurfaceQualitySoA {
    int n_subcatch = 0;
    int n_landuses = 0;
    int n_pollutants = 0;

    std::vector<double> buildup;

    std::vector<double> washoff_conc;

    std::size_t bu_idx(int sc, int lu, int p) const {
        return static_cast<std::size_t>(sc) * static_cast<std::size_t>(n_landuses * n_pollutants)
             + static_cast<std::size_t>(lu) * static_cast<std::size_t>(n_pollutants)
             + static_cast<std::size_t>(p);
    }
 
    void resize(int n_sc, int n_lu, int n_poll);
};
 
// ============================================================================
// Landuse quality solver
// ============================================================================
 
class LanduseSolver {
public:
    void init(int n_landuses, int n_pollutants);

    void computeBuildup(SurfaceQualitySoA& sq,
                        const double* area, const double* curb_length,
                        double dt, int n_subcatch);

    void computeWashoff(SurfaceQualitySoA& sq,
                        const double* runoff, const double* area,
                        int n_subcatch);

    void applyCoPollutant(SurfaceQualitySoA& sq,
                          const double* runoff, const double* area,
                          const int* co_pollut, const double* co_frac,
                          int n_subcatch);

    std::vector<BuildupParams> buildup_params;
    std::vector<WashoffParams> washoff_params;
    int n_landuses_ = 0;
    int n_pollutants_ = 0;
};
 
} // namespace landuse
} // namespace openswmm
 
#endif // OPENSWMM_LANDUSE_HPP