Agriculture Loss Assessment: Some Practical Considerations |

Agriculture Loss Assessment: Some Practical Considerations

Jiban Krishna Biswas, PhD

    11 November, 2017 12:00 AM printer

Agriculture Loss Assessment:  Some Practical Considerations

Jiban Krishna Biswas, PhD

Scientists could predict the exact pathway and the hitting time of a cyclone but there is no way to get your crop saved from the catastrophe as you cannot ask the crop to run away for a safer place. At best you could ask the farmer to harvest their crop as soon as possible till the depression is in the deep sea.

We have the same experience in Bangladesh in early May 2008 when the cyclone “Nargis” changed its way a little towards the southern coast of Myanmar. However, we have a pathetic experience of the cyclone Sidr that tore across the south-western coastal region of Bangladesh on 11 November 2007 causing a huge loss to the economy of the country. The most notorious Bhola cyclone occurred almost in the same day (12 November) in 1970 to cause an unprecedented catastrophe in the history of human civilisation.


The adversity due to a cyclone is nothing new not only to us but to many other countries like, the Philippines, Japan, Korea, India, some of the coastal states of the USA and the Pacific island countries. As a human being, we are still undone against the mighty strength a cyclone. The best thing we could do aftermath a cyclone is to assess the damage and loss to get rid of the nightmare as early as possible. Therefore, assessment is an important means towards the recovery from devastation. As an agricultural expert, our responsibility is to seek early recovery from any loss related to Agriculture. Under these kinds of circumstances, rice comes as a priority one in the list of crops. Unfortunately, the historical data of crop loss we have on rice or the other crop is not beyond question. Japan has its data since 1948. Those data were based on their field survey. The recent data must be satellite imagery-based with some simulation modelling techniques. The Japanese scientists have some mathematical models derived from their simulated experiments in the 1950s to 1960s. We are familiar with one of their mathematical equations is Y = aV3/2logt + b where V is the velocity of the cyclone (meter/second). The V across the rice field is one-third of the recorded data of the meteorological station. So they have considered the V accordingly. “t” refers to the time of occurrence of a cyclone. “a” and “b” are the coefficients estimated through a series of experimentation and calculation. Simulating cyclone, no research has yet been considered in our country. Koreans are doing some studies right now. We may borrow their results to implement in our conditions.

The general recommendation is immediate field survey after the occurrence of a cyclone or any kinds of natural calamities like flood, drought etc. The involvement of the Bureau of Statistics of the Government is a must. In case of any kind of crop loss assessment, the Department of Agricultural Extension (DAE) plays the pivotal role to collect the data from the field. The Research Institutions like BRRI, BARI, SRDI etc. have an opportunity to understand the nature some particular problems and extent of damage in depth. The officers at the field level have a little scope to take part in the crop-loss assessment study immediately after the devastation, because they have to involve in the emergency relief and rehabilitation (R&R) activities as a priority task. So it is very difficult to maintain the exact methodology (random sampling or the like) of statistics for all the affected areas. Sometimes the survey-people have to guess the situation of the places hard to access. However, that is only done to have a preliminary understanding immediate after the calamities. In reality, it is better to extend life-saving help to the victims prior to approach for the information related to the damage and loss. I have an experience as a member of a survey team from BRRI (Bangladesh Rice Research Institute) to collect data aftermath the Sidr. We approached the hot spots of Pathorghata, Borguna and Kalapara, Potuakhali, 14 days after the occurrence of the cyclone. On the way, we visited some spots of Gournadi, Barisal. By that time emergency relief and rehabilitation works were in progress with full swing and DAE had their reports on the overall survey of all crops, vegetables and plantations crops ready. But the BRRI target was to get the some scientific information with respect to the crop-growth stage-specific information so that the data could be utilized to interpret the exact loss of the crop.

We started our survey from the village Lathimara, at the estuary of the river Baleshwar, the hitting point of Sidr. As per the daily Ittefaq (17 November 2007), the wind velocity at the point of hitting the land was 260-280 kilometres per hour. The inhabitants of the village witnessed the blazing wave of around 20-25 ft high. The cyclone completely demolished all the establishments, trees, and crops, livestock etc. of the village into debris within a moment. The local aman rice varieties Kajol sail and Sadamota were the dominating crops in and around the village.Fifty percent of the transplanted crops were in their post-booting to flowering stage. The next surveying spot was 2-3 kilometres from the village. The velocity of the cyclone must not be different from that of the mouth of the Baleswar but the wave height reduced to 7-10ft. The relatively low lying rice fields were ponded with saline water for a week or so and the plants were decomposed from the base. Leaves were got tattered and dried out in a dry land.


The crop at the post-dough stage was severely affected. The introduced modern variety BR11 and BRRI dhan41 (demonstration plot) were seen standing at their maturity stages as the growth duration of those crops were shorter than the landrace varieties. But they experienced a severe shattering loss. Even those crops were supposed to yield 50 percent as compared to the normal conditions. However, due to soaking in the saline water, the plant got infected with different kinds of diseases so as to make the crop unfit for seed collection. Thereafter, we approached two kilometres eastward along the Kuakata sea beach. The wind speed was 200 kilometre per hour (as per DAE officials) in that spot during Sidr.


The tidal surge broke away the protection barrage to inundate the rice fields with saline water. This area was also dominated by the landrace transplanted aman rice like Kajol sail, Kuriaghrani, Dinga and Swarnamashuri (Pajam!). Most of the crops were inundated in its maturity stage. We had a data recorded on 2 November 2007 from the DAE authority. As per the data, 50 percent of the crops were in the maturity stage and 30 percent on the halfway to maturity. The remaining 20 percent were in the flowering stage. Around 70-80 percent of the crop was supposed to be sterile. So the average harvest was assumed not more than 50 percent. However, a few of the plots were observed more or less in better condition than the others most probably due to the zigzag movement of the cyclone. This was the methodology we followed might not be precise but not avoidable to satisfy the emergency and specific needs.


For estimation of Damage and Losses of Cyclone Sidr, JDLNA (Joint Damage Loss and Needs Assessment) team followed the UN-ECLAC (UN Economic Commission for Latin America and the Caribbean) prescribed methodology.  Generally, a disaster has two types of socio-economic impacts: Damage and Loss. The sector-wise damage and loss assessment are done through a bottom-up approach. The steps to assess the damage and loss are as follows:

1.     Define pre-disaster baseline
2.     Develop a post-disaster situation
3.     Estimate damage and losses on the sector basis
4.     Estimate overall amount of disaster effects
5.     Estimate macroeconomic impact
6.     Estimate impact on the personal/household income

The crop is a sub-sector under the sector agriculture. The other sub-sectors are Livestock, Fisheries and Forestry etc. The typical damage includes in crop sub-sectors are land, irrigation and drainage structure, storage facilities, stored or harvested crop outputs, agricultural inputs, farm buildings and sheds, farm equipment and machinery, farm roads, plantation crops etc. In order to estimate the damage and loss, it is important to have the baseline information (Pre-disaster situation) for each of the crops with historical data on area, yield and total production at every step of administrative units. Projected information of the year experienced disaster is also quite useful. Just after the disaster, it is important to understand the situation if the crop (annual and perennial) in terms of area and yield along with the physical assets like land, farm machinery & irrigation and drainage infrastructure, input and output stocks, perennial crops etc. The estimation of damage to physical assets is done by multiplying the number of units of fully damaged assets by the replacement value or by the prevailing market price. In the case of the partially damaged assets are estimated by the same way above just by multiplying by unite-wise repairing cost. The estimation of production loss for annual crops is done with respect to crop growth stage and the extent of the damage. The production loss is equal to full loss if the crop is fully destroyed or partially loss if the crop yield is declined. If the loss is incurred at the beginning of the annual crop, the estimation is done considering whether the crop could be replanted or not.

There are two methods of full crop production loss. The data related to crop area, average yield crop production and farm gate price for a crop with respect to the baseline, pre-disaster forecast and post-disaster are essential. Crop production loss is estimated from difference of the value of pre- and post-disaster crop produces. If neither the baseline date nor the corresponding forecasts are available another method is followed to estimate the production loss. In this case, the damaged crop area is multiplied by the average crop yield for a normal year and the current farm gate price.


To estimate a partially damaged crop, the yield is estimated by multiplying percent decline in the average yield of the normal year. The production loss is estimated from the difference between the total production of the damaged area and the estimated total production after the disaster and multiplied by the farm gate price. In the case of perennial crops (plantation trees) the loss is estimated depending on the nature of damage to the plantation crop. The damage is considered equal to the cost of replanting the destroyed the perennial crops. The loss is equal to the sum of the value of the full of the standing crop production loss plus the valued of production loss over a period of time required to mature the plant or tree.

We are in a country of having extreme events quite often. Therefore, we have to get ready with a sound and swift damage and loss assessment techniques required to formulate a comprehensive early recovery from the after effect of a disaster.


The writer is the Director General (Retired), Bangladesh Rice Research Institute, Gazipur