NEP-Hydro-Climate

This repository contains scripts for hydrological modeling and climate change impact assessment on design flood statistics for small hydropower projects in Nepal. A process-based hydrological model (HBV) enhanced with a Light Gradient Boosting Machine (LGBM) post-processor is used to simulate streamflow under historical and future climate scenarios, enabling assessment of changes in key design flood statistics under future climate conditions.

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Overview of Scripts

The repository is organized into four categories: data preprocessing, model calibration and simulation, figure generation, and core model implementation.

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📦 Preprocessing Scripts

Script	Description
1.1.select_hpp.py	Selects small hydropower projects in Nepal from the DoED database.
1.2preprocess_obs_streamflow.py	Preprocesses observed streamflow data for input into the HBV model.
2.1download_era5_data.py	Downloads ERA5 reanalysis climate data for the selected region and period.
2.2preprocess_era5.py	Processes ERA5 data to make it suitable for HBV model input.
2.3combine_era5.py	Combines ERA5 climate data with observed streamflow for model calibration.
3.1download_hist_climate_data.py	Downloads historical climate model outputs from NASA's Center for Climate Simulation.
3.2preprocess_hist_climate_data.py	Preprocesses historical climate data for hydrological modeling.
3.3combine_hist_climate.py	Combines processed historical climate variables into HBV-compatible format.
4.1download_future_climate_data.py	Downloads future climate projections from NASA's Center for Climate Simulation.
4.2preprocess_future_climate.py	Processes future climate data for hydrological simulations.
4.3combine_future_climate.py	Combines future climate variables into a format suitable for HBV simulations.

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⚙️ Model Calibration and Simulation Scripts

Script	Description
5.1hbv_era5calibrate.py	Calibrates the HBV model using ERA5 data and observed streamflow.
5.2postprocessor_hbv.py	Develops LGBM post-processing models to correct biases in HBV simulations.
5.3hbv_era5simulate.py	Simulates streamflow using ERA5 data and calibrated HBV parameters.
5.4hbv_ncss_simulate.py	Simulates streamflow using historical climate model data.
5.5hbv_ncss_simulate_future.py	Simulates future streamflow using projected climate scenarios.

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📊 Figure Generation Scripts

Script	Description
6.1hbv_era5evaluate_plot.py	Evaluates model performance using metrics like NSE during calibration and validation.
6.2timeseries_era5plot.py	Generates time series plots of simulated streamflow and precipitation during validation.
6.3return_period_plot.py	Computes and plots return period statistics (e.g., 25-, 50-, and 100-year floods).
6.4relative_change_plot.py	Computes and plots relative changes in flood magnitudes under future climate scenarios.

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🤖 Hydrological Model

Script	Description
hbv_model.py	Core implementation of the HBV hydrological model used in all simulations.

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