#include <stdio.h>
#include <math.h>
#include <stdlib.h>

/* soil moisture in the root zone
 * Makin, Molden and Bastiaanssen, 2001
 */
double soilmoisture(double evap_fr)
{
    return ((exp((evap_fr - 1.2836) / 0.4213)) / 0.511);
}
