Climate change and crops in haor areas
Role of climate change on flash flood is yet to be established. A recent study by BUET, reveals that pre-monsoon rainfall and its intensity may increase in the future
A.K.M. Saiful Islam
Starting from March 27, the northeast parts of the country experienced severe flash floods. While the central and middle parts of India continue to be under the tight grip of heatwave conditions, in fact hot weather conditions, the northeast parts of Bangladesh and India observes heavy rainfall in the last week. In India, temperatures across these regions, Odisha, Chhattisgarh, Jharkhand, Vidarbha region are also settling above 42-degree mark according to the Skymet Weather report. A cyclonic circulation is over Sub-Himalayan West Bengal and adjoining areas was persistent over the last week of March and early April. This circulation bring moisture by the strong winds from the Bay of Bengal towards the Meghalaya and Assam regions. After cooling and condensation of the moisture due to the uplift over the Meghalaya hills, orographic rainfall occurred over this Meghalaya and Asham region. Another cyclonic circulation formed over the Assam region in the past couple of days.Due to the two cyclonic circulations and the persistentcyclonic circulation over Assam, it will continue to give heavy to extremely showers over Meghalaya and Assam. Similar situation was observed in the last year during middle and late of April.Situation in the last year. In 2016, Boro was harvested in many places before flash flood occurred and therefore situation was not that worse comparing to this year. In this year, due to heavy downpour in the Meghalaya and Asham regions which brought early flash, Boro crop has been completely damaged. According to the Department of Agriculture Extension (DAE) data Boro has been cultivated on 0.29 million hectares haor areas compromising of Sunamganj, Hobiganj, Sylhet, Moulvibazar, Netrakona and Kisoreganj districts. The affected areas in the haor region consists of the 6% of the countrys total Boro cultivation this year. About 15,000 hector of in the Kishoreganj areas are currently under water. Similar situation can be found in the Habiganj, Sunamganj and Netrokona district. Besides heavy rainfall and early flash floods, the annual repair and construction of earthen embankments were not completed in many places as reported by the local newspaper.
Role of Global Warming and Climate Change
Role of climate change on flash flood is yet to be established. A recent study by BUET, evident that pre-monsoon rainfall and its intensity will be like to increase in the future. The probability of the occurrence of flash flood will likely be higher in the future due to climate change. Changes of weather phenomenon and increase of extreme weather events has already been observed in all over the world. In 2016, new record of warming was set comparing to the modern temperate record dated since 1880 according to the NASA. The mean annual temperature of the planet was warmer above 0.99 degree Celsius than the mid-20th century. The average temperature of the planet has risen about 1.1 degrees Celsius since the late 19th century. The extent of the Arctic sea ice of the first six months of 2016 also set records for the smallest with respect to the monthly Arctic sea ice extent since consistent satellite records began in 1979. Due to the El Nio events both 2015 and the first third of 2016, warming in the tropical Pacific has increased 0.12 degrees Celsius. Australian Brue of Meteorology (BOM) has already placed on El Nio watch as chances of developing El Nio during July is about 50.SkymetWeather has predicted that the upcoming Southwest Monsoon in India is likely to be below normal at 95% (with an error margin of +/-5%) of the long period average (LPA) of 887 mm for the four-month period from June to September.
El Niowouldaffectnegatively the production of the Amanrice cropsduring the upcomingKharif-II seasons in Bangladesh.
Managing Flash Flood in Haor Areas
People of Haorareasrelies heavily on Boro production. Flash flood can plunge in overall rice production in the country which might further increase the price of rice. Therefore, several measures should be taken for managing flash flood in haor areas and reduce the risks associated with it.
1. Construction of the temporary earthen embankment by Bangladesh Water Development Board (BWDB) must be completed before the start of the pre-monsoon season.
2. Depending on the topographyand sediment load of the river, Rubber dam can be constructed to save Boro crops which iscurrently practiced by the Local Government Engineering Department (LGED).
3. Rivers and canals should be excavated before the pre-monsoon season to improve the water carrying capacity.
4. Crop Insurance can be introduced to reduce the flash flood related risks in haor areas.
5. Compensation and relief can be given to the effected people during and after the flash flood event.
6. Bangladesh Rice Research Institute (BRRI) and Bangladesh Institute of Nuclear AgricultureInstitutehave inventedshort (120-days) durational varieties of rice (e.g., BRRI dhan33, BRRI dhan39, or BINA 7).In collaboration with the Department of Agricultural Extension (DAE) such short varieties rice can be introduced in haor areas.
7. The current danger level for flood is designed for the monsoon flood. Flood warning level for the pre-monsoon flash flood for the haorareas should be established and flash flood warning should be provided by BWDB.
8. A project on providing Flash Flood Forecasting and Early Warning Systems (FFEWS) currently under development which is funded by IFAD and LGED in collaboration with BUET, BMD and BWDB should be integrated in the future for providing accurate early warnings to the haor areas.
Immediate and necessary action should be taken to providecompensation for rehabilitatingflash flood affected people in haor areas. We also need to be prepared for the erratic monsoon rainfall which is likely because of global warming and climate change.
The writer is a Professor of the Institute of Water and Flood Management at the Bangladesh University of Engineering and Technology, Bangladesh.
Email:akmsaifulislam@iwfm.buet.ac.bd
