Climatic Hazards Hotspot Map
2.4 Test protocol
2.4.1 Difference in difference and identification of individual-events
On order to test as rigorously as possible the potential impact of specific events on the nutrition and food security of child/households, we followed a quasi-experimental approach. Wherever it was possible, we adopted a difference in difference (DiD) protocol (Zar 2010).
In our case this DiD protocol means that we compare the value of a particular indicator (nutrition or food security) obtained for two groups of communities:
one group affected by a specific event (treatment), and one group not affected by the same event (control), and that the comparison is run before and after the period when that specific event occurs.
The DiD protocol implies therefore a series of 4 stringent conditions:
(i) Treatment communities (i.e.
communities that were affected by a particular event) can be identified amongst these that had been included in the NSP. This, in itself, implies that:
a. Shock/stressor data are available for the region/district that includes
(or are sufficiently close to) these communities;
b. These affected communities were sampled at the appropriate time, i.e. both before and after the occurrence of that event;
(ii) We are able to identify control communities, amongst these that had been included in the NSP.
This, in itself, implies that:
a. These control communities were not affected by the event -as was verifiable using the climate databases;
b. These non-affected
communities were sampled by the NSP at the same time both before and after the event occurred in the affected communities
Clearly these conditions limited the number of testable cases for which the DiD protocol can be applied fully. This had some important implication for our work. In particular in the case of flash flood no single testable event was possible amongst the series of flash flood events that had been identified, essentially because flash floods –even if they occur relatively often- are very localized both geographically and temporarily, making the matching process impossible in our case for
the period considered.7 For salinity intrusion the slow onset nature of the process also implies that the DiD approach cannot be applied. Instead for salinity a simple difference in means (DiM) test was applied whereby the food security and nutritional indicators of communities living in the affected areas (treatment) were compared to the same indicators estimated for communities living outside the affected area (control).
For all the other shocks, applying the DiD was possible for the events that were satisfying the 6 conditions listed above. Thus, for flood, eight flood events were identified. Table 6 shows the full list of these flood events (location, date, duration). Amongst these the 1998 and 2004 events were major events (with the flood level remaining over the DL for more than 30 subsequent days in a large number of upazilas), while the other 6 events were less significant.
For drought, three drought events involving four upazilas (Naogoan, Kaunia, Shahjadpur, and Pirganj) were identified for which NSP data is available for both treatment and controlled communities. These are listed in Table 7.
7 In addition, the river danger level data was missing for several stations in the areas where flashfloods were occurring, preventing us from being sure that the control communities were true control, i.e. effectively not affected by flashflood.
Table 6. List of flood events included in the DiD analysis
Table 7. List of drought events included in the DiD analysis Year
Year
Months
Months Type of event
Areas affected, with the number of days flooded in brackets
Areas affected, with the number of months of drought in parentheses 1998
1999
2000 2001 2002
2003
2004
2005
1998 1999 2003
July - September
July - September
June - September August - October June - August
July
July - October
October
June April-May February
Moderate Severe Moderate
Shahjadpur, Sirajganj (74); Nabinagar, Brahmanbaria (64); Serajdikhan, Munshiganj (55);
Sreepur, Gazipur (53); Jamalpur Sadar, Jamalpur (31); Naogaon Sadar, Naogaon (17) Shahjadpur, Sirajganj (60); Naogaon Sadar, Naogaon (15); Pirganj, Thakurgaon (5);
Serajdikhan, Munshiganj (3)
Shahjadpur, Sirajganj (52); Serajdikhan, Munshiganj (3) Shahjadpur, Sirajganj (25); Pirganj, Thakurgaon (14)
Shahjadpur, Sirajganj (28); Nabinagar, Brahmanbaria (11); Jamalpur Sadar, Jamalpur (7);
Serajdikhan, Munshiganj (6)
Shahjadpur, Sirajganj (18); Nabinagar, Brahmanbaria (9); Naogaon Sadar, Naogaon (4);
Serajdikhan, Munshiganj (11)
Shahjadpur, Sirajganj (95); Nabinagar, Brahmanbaria (30); Naogaon Sadar, Naogaon (30);
Serajdikhan, Munshiganj (17); Jamalpur Sadar, Jamalpur (15); Fenchuganj, Sylhet (15);
Sreepur, Gazipur (15)
Naogaon Sadar, Naogaon (12)
Pirganj, Thakurgaon (7)
Naogaon Sadar, Naogaon (10); Kaunia, Rangpur (7) Shahjadpur, Sirajganj (4)
NSP-sampled areas which were not affected by flood between 1998 and 2006: Hathazari, Chittagong; Chouddagram, Comilla; Cox’s Bazar Sadar, Cox’s Bazar; Kaunia, Rangpur; Fakirhat, Bagerhat; Kaliganj, Jhenidah; Debhata, Satkhira; Patharghata, Barguna; Lalmohan, Bhola; Rajapur, Jhalakathi;
Patuakhali Sadar, Patuakhali; Habiganj Sadar, Habiganj; Sreemangal, Moulavi Bazar; Jamalganj, Sunamganj.
Areas with river station data not available and thereby excluded from analysis are: Gangni, Meherpur; Atpara, Netrokona.
NSP-sampled areas in the drought zone with no periods of low rainfall from 1998-2006: Jamalpur Sadar, Jamalpur; Kaliganj, Jhenidah; Gangni, Meherpur.
Fig.9. Maps of all the different affected (treatment) and non-affected (control) NSP sites included in the quantitative analysis
88o0’0”E
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22o0’0”N 22o0’0”N
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25o0’0”N 25o0’0”N
26o0’0”N 26o0’0”N
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21o0’0”N 21o0’0”N
22o0’0”N 22o0’0”N
23o0’0”N 23o0’0”N
24o0’0”N 24o0’0”N
25o0’0”N 25o0’0”N
26o0’0”N 26o0’0”N
88o0’0”E
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Table 8. List of cyclone events included in the DiD analysis
Date Wind-speed Areas affected with the proportion of area impacted by the cyclone path in parenthesis
May 19, 1998 November 22, 1998
October 28, 2000 November 12, 2002
60 55
35 55
Partially: Hathazari, Chittagong (90%); Cox’s Bazar Sadar, Cox’s Bazar (10%)
Completely: Patharghata, Barguna; Rajapur, Jhalakathi; Patuakhali Sadar, Patuakhali Partially: Lalmohan, Bhola (80%)
Partially: Serajdikhan, Munshigonj (98%); Fakirhat, Bagerhat (70%) Completely: Kaliganj, Jhenidah; Debhata, Satkhira
Partially: Shahjadpur, Sirajganj (50%)
Areas with no cyclone events from 1998-2006: Sreepur, Gazipur; Jamalpur Sadar, Jamalpur; Atpara, Netrokona; Nabinagar, Brahmanbaria;
Chouddagram, Comilla; Naogaon Sadar, Naogaon; Kaunia, Rangpur; Pirganj, Thakurgaon; Gagni, Meherpur; Habiganj Sadar, Habiganj; Sreemangal, Moulavi Bazar; Jamalganj, Sunamganj.
For cyclones, four events were identified. These are indicated in Table 8 along with the percentage of the upazilas that were affected by these cyclones. Note that because Sidr happened in 2007, that is after the NSP was terminated, it is not amongst the events which could be tested.
Fig.9 is a summarizing map that represents all the different upazilas which were included in the
quantitative analysis. In red are the affected (treatment) areas, and in
green the control areas for droughts, floods, cyclones and salinity.