FloodVulnFunctions.py

#a collection of Python functions for vulnerability analysis and flood loss modelling
#created by Andreas Paul Zischg

import math
import numpy as np

#**************************************************************************
# vulnerability function (Totschnig et al. 2011)
# this function calculates the degree of loss of a buildung on the basis of deposition depths of floods with sediment transport
# Totschnig, Reinhold; Sedlacek, Walter; Fuchs, Sven (2011): A quantitative vulnerability function for fluvial sediment transport. In: Nat Hazards 58 (2), S. 681–703. DOI: 10.1007/s11069-010-9623-5.
#**************************************************************************
def vulnerabilityTotschnig(flowdepth):
    if float(flowdepth) >=0.0:
        u = (float(flowdepth)+1.442)/1.442-1
        v = math.pow(u, 2.233)
        w = -0.443*v
        x = 1-math.exp(w)
        if x >=0.0 and x <=1.0 :
            vulnerabilityTotschnig = x
        elif x>1.0:
            vulnerabilityTotschnig = 1.0
        elif x<0.0:
            vulnerabilityTotschnig = 0.0
    else:
        vulnerabilityTotschnig = 0.0
    return vulnerabilityTotschnig