notes.txt

Can you suggest some code to make up soil water retention cureves? I know that it is not accurate to make up those curves, but I try to align my read data with an weather API. So for a certain time and GPS coordinates, the API will provide a volumetric water content. I also read soil tension values from my sensors on site. I want to create now a custom soil water retention curve, that aligns my sensor readings with the API, so that  my machine learning models training data can align with my target variable.

Creating soil water retention curves involves interpolating or fitting mathematical functions to represent the relationship between soil water content and soil tension. One common approach is to use the van Genuchten model, which is widely used in soil science. The van Genuchten model has parameters that can be adjusted to fit observed data.

Here's a simple example using the van Genuchten model in Python with the scipy.optimize module for curve fitting:

python
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import numpy as np
from scipy.optimize import curve_fit
import matplotlib.pyplot as plt

# Sample data
tension_data = np.array([10, 20, 30, 40, 50])  # Replace with your actual soil tension data
water_content_data = np.array([0.2, 0.3, 0.4, 0.5, 0.6])  # Replace with your actual volumetric water content data

# Define the van Genuchten model function
def van_genuchten(tension, alpha, n, m, theta_r, theta_s):
    return theta_r + (theta_s - theta_r) / (1 + (alpha * tension) ** n) ** m

# Initial guess for parameters
initial_guess = [0.01, 2, 0.5, 0.1, 0.4]

# Fit the model to the data
params, covariance = curve_fit(van_genuchten, tension_data, water_content_data, p0=initial_guess)

# Generate a high-resolution curve using the fitted parameters
tension_curve = np.linspace(min(tension_data), max(tension_data), 100)
water_content_curve = van_genuchten(tension_curve, *params)

# Plot the data and the fitted curve
plt.scatter(tension_data, water_content_data, label='Observed Data')
plt.plot(tension_curve, water_content_curve, label='Fitted Curve', color='red')
plt.xlabel('Soil Tension')
plt.ylabel('Volumetric Water Content')
plt.legend()
plt.show()
This script defines a van Genuchten model function and fits it to your soil tension and water content data. You can adjust the initial guess and modify the model function as needed based on your specific requirements.

Keep in mind that this is a simple example, and you may need to adapt the model or use more sophisticated models depending on the characteristics of your soil and the observed data.