What are the major challenges of assessment of benefits from flood management projects?

There are several challenges of assessment of direct benefits from flood management projects.

First, flood management projects are usually taken up in the aftermath of a damaging flood where information on loss and damage from such floods is available only after the flood.

Second, in most cases either the flood damage data from past flood events are not available or are not reliable enough as a result of a lack of standardized damage assessment procedures.

Third, In addition to the damage prevented, another direct benefit of flood management schemes is the increase in area which may become available for cultivation as well as for other economic uses due to reduced flood risks.

Forth, assessment of the fertilizing value of silt due to inundation of flood plains if prevented because of flood protection projects needs to be included as a benefit lost or a negative benefit. However, the assessment of the fertilizing value of silt will obviously vary from area to area depending upon its quality and recurrence and very few precise methods are available for assessing this and no general guidelines can be prescribed.