1. CHARACTERIZATION OF THE DAMAGES DUE TO CYCLONIC STORM EVENTS IN INDIAN COAST
Ramakrishna Nallathiga
Knowledge Manager
Centre for Good Governance
Hyderabad (INDIA)
ASCE – EWRI Conference, Dec 18-20, 2006

2. Structure Introduction Motivation Methodology Results Comparison
Formulation
Establishment
Results
Comparison
Caveats
Implications

3. Introduction
Monsoon is an important phenomena for India with reference to rainfall, which is important for agricultural production and natural resources
It is the cyclonic storms that form in the seas along both the coasts which give rise to monsoon rainfall upon crossing of the coasts
The crossing of cyclonic storms also causes severe rainfall in coastal zone, storm surges along coastline and very severe rainfall on mainland
The crossing of cyclonic storms, therefore, leads to a variety of damages to:
human population and settlements,
agriculture and livestock,
infrastructure and
industries

4. Primary Impacts
Secondary and Tertiary Impacts

5. Motivation
The occurrence of cyclonic storms is not peculiar to Indian sub-continent, but common to several tropical countries, which are under the risk of storms and several other damages
The damages on account of natural disasters, particularly cyclonic storms, has become an important area of concern to international agencies like the World Bank
India has a good database of storm occurrences and crossings, but the information on the impacts i.e., damages, is still scattered, not complete and not well maintained.
Event studies exist but few cross-sectional studies
Given the rising importance of increasing damages associated with cyclonic storm events, this study made an attempt to characterize them in terms of storm characteristics.

6. Methodology
Empirical study of the records of cyclonic storm events and damages/impacts
Formulating relationships between storm characteristics and damage categories
Correlation and Parametric regression analysis
Statistical testing and Comparison with similar studies
Implications (including limitations)

7. Formulation Damages due to the Cyclonic storms (D) are:
(i) inversely related to Storm Pressure (P)
(ii) directly related to Wind Speed (V)
Or, simply expressed,
Ds = f(Ps) and Ds = f(Vs)
Upon examination of data, we modify it to
Log (Ds) = f(Ps) and Log (Ds) = f(Vs)
For testing, the mathematical forms are
Log (Ds) = +(Ps)+  and Log (Ds) = +Vs + 
With respect to s, we expect –ve sign associated with P and +ve sign associated with V

8. Establishment Examination of correlation among variables
Simple bi-variate relationships through statistical regressions using data sets by estimating the coefficients (s) and their signs
Examining the relationships in terms of
statistical significance of parameter coefficients,
goodness of fit of relation i.e., R square
Comparing the explanability of the relationship with such experiments in the US

9. Results - Correlation Analysis
Log (Deaths)
Log (Crop area)
Log (Losses)
Log (Houses)
Surface Pressure
Wind Speed

10. Results - Regression Analysis
Dependent Variables
Log (Deaths)
Log (Crop area)
Log (Losses)
Log (Houses)
Independent Variables
Constant
25.767
5.7878
27.652
33.138
Surface Pressure
*** *
***
Goodness of Fit (R2)
0.3341
0.0007
0.17
0.4421
No. of observations (n) 38 13 19 21
1.0068
4.9693
2.5555
3.0888
Wind Speed
0.016***
0.0001
0.0163
0.025***
0.3328
2e-05
0.0548
0.3404 41 14 22
*** Statistically significant at more than 99% confidence level
* Statistically significant at 90% confidence level

19. Comparison
When compared to the similar functional relationships in the US e.g., Pethak and Atkinson (1987), it appears that the association between storm characteristics and two of the major impacts, mortality and damages (fixed property like houses), is more explainable in case of India but the strength of relationship is almost same.
The association appears to be very poor in case of the US as evident from the explainability of the model fit (R2 values) shown in table 4, which are much lower than those corresponding in Indian context

20. Caveats
The study concerned with direct impacts alone, but indirect impacts may also be significant and larger
Other intervening variables (most local), such as land use, soil properties, type of crop and damage sustained, may determine the impact than storm characteristics alone
The method is not useful for comparison across the time periods due to natural growth in many of the parameters like population, houses, livestock, agricultural crop area/production
Normalisation of damages and such advanced methods may make the damages comparable but are plagued by data gaps of concerning variables
The relationships also need to be extended to include other variables to make the models more robust and useful in the decision making with respect to management interventions/ strategies

21. Implications
Nevertheless, the results point to the fact that most damage categories are related to the cyclonic storm characteristics
This assumes importance as India has been experiencing some very severe storms, like some other parts of the world, albeit with lesser frequency
Also, with rising intensity of storms, which is now attributable to global warming, the damages would also rise in future if warming lead to stronger storms
The number of intense storms crossing the coasts has also been a worrying concern, but such effects appear to be variable with regions e.g., In India there was a decline in number in the last decade but they increase in the US
Besides the risk arising from storm events, the vulnerability of human and natural systems, particularly on the coasts, might also rise, if current human population and human activities concentrate on coast and are exacerbated if there are severe local problems