Sumaiya Jarin Ahammed
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Rajab Homsi
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Najeebullah Khan
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Shamsuddin Shahid
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Mohammed Sanusi Shiru
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Morteza Mohsenipour
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Kamal Ahmed
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Nadeem Nawaz
Faculty of Water Resource Management, Lasbela University of Agriculture, Water and Marine Sciences (LUAWMS), Uthal, Balochistan, Pakistan
Nor Eliza Alias
Department of Water and Environmental Engineering, School of Civil Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Ali Yuzir
Centre for Environmental Sustainability and Water Security (IPASA), Universiti Tecknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
Water stress · Crop moisture index · Climate change · Trends · Bangladesh
Crop-Soil-Water Management
2 Climate and agriculture of Bangladesh Geographically, Bangladesh lies between 20°34′N–26°38′N latitude and 88°01′E–92°41′E longitude in South Asia. The climate of the country is the tropical humid type, in which seasonal rainfalls vary widely, temperatures are moderately warm, and humidity is high (Shahid 2010). Rainfalls of 1400 mm occur at the western part while they could be more than 4400 mm in the eastern part of the country with more than 75% of the occurrences during monsoon season. The month of July has the highest rainfall records. Bangladesh’s spatial and temporal variability in rainfall is a very relevant characteristic of the climate of the country. The average temperature in winter ranges between 7.2 and 12.8 °C and the summer between 23.9 and 31.1 °C. The coldest month in the country is January while the hottest one is May.
Bangladesh has four climatic seasons, namely (i) the dry winter occurring between December and February, (ii) hot summer pre-monsoon occurring between March and May, (iii) rainy monsoon occurring between June and September and (iv) post-monsoon autumn lasting between October and November. Kharif (May–October) and rabi (December–May) are the two main crop-growing periods of the country. Rain-fed crop is growing in kharif season when enough moisture is available due to high rainfall while the crops in rabi season are grown under irrigation due to a little or no rainfall during this season. A transition season occurring between March and May called pre-kharif which is characterized by unreliable rainfall and thus provides intermittent moisture supply to crops.
Rice is the driving force of Bangladesh agriculture, which alone shares about 96% of the total cereal food supply. Boro rice cultivated predominantly during pre-kharif season accounts for over 60% of total rice production. Aman rice cultivated during monsoon shares about 43% of total rice production. Therefore, water stress during pre-monsoon and monsoon has severe implications on food security of Bangladesh.
shares about 43% of total rice production (Pingali 1998). Therefore, water stress during pre-monsoon and monsoon has severe implications on food security of Bangladesh.Data quality was checked using subjective double-mass curve method (Kohler 1949) and the objective Student’s t test (Panofsky and Brier 1958). For all rainfall stations, the double-mass curves were found to be mostly straight confrming the data quality. There was no missing period in the time series for the stations considered. Homogeneity was assessed by determining whether any potential changing point is present in the time series using Student’s t test on the data series of diferent stations. The Student’s t test statistics were found to be between 0.67 and 0.89 for all the stations. It is inferable that there was no potential breakpoint in time series at any of the stations as the statistics of the Student’s t test were much below the corresponding test statistics at a signifcance level of 0.05.
double-mass curves were found to be mostly straight confrming the data quality. There was no missing period in the time series for the stations considered. Homogeneity was assessed by determining whether any potential changing point is present in the time series using Student’s t test on the data series of diferent stations. The Student’s t test statistics were found to be between 0.67 and 0.89 for all the stations. It is inferable that there was no potential breakpoint in time series at any of the stations as the statistics of the Student’s t test were much below the corresponding test statistics at a signifcance level of 0.05.
3.2.2 Run theory for identifcation of crop water stress Run theory was used for the identifcation of diferent characteristics of water stress from CMI. In this method, a moisture defcit period coincides with a “negative run” (Yevjevich 1967). The maximum defcit of CMI, number of weeks with CMI below zero and the cumulative CMI during the period when CMI below zero are estimated for all the moisture defcit cases for the whole period. These values are then used to estimate the diferent characteristics of crop water stress. Six indices related to crop water stress were calculated for annual, monsoon and pre-monsoon seasons, and therefore, a total of 18 indices were estimated. The summary of the indices used for the assessment of crop water stress.
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