Cropping Systems and their Diversity in Khulna Region

This study includes the existing cropping pattern, cropping intensity and crop diversity of Khulna region. A pre-designed and pre-tested semi-structured questionnaire was used to collect the information and validated through organizing workshop. Single T. Aman cropping pattern was the most dominant cropping pattern in Khulna region existed in 17 out of 25 upazilas. Boro-Fallow-T. Aman cropping pattern ranked the second position distributed almost in all upazilas. Boro-Fish was the third cropping pattern in the region distributed to 17 upazilas with the major share in Chitalmari, Dumuria, Rupsha, Tala, Kalaroa, Mollahat, Terokhada, Bagerhat sadar, Fakirhat, Rampal and Phultala upazilas. Single Boro rice was recorded as the fourth cropping pattern covered 18 upazilas with the higher share in waterlogged area of Dumuria, Mollahat, Tala, Bagerhat sadar, Fakirhat and Rampal. The highest number of cropping patterns was recorded in Kalaroa (26) followed by Tala (24) and the lowest was reported in Mongla (5). The overall crop diversity index (CDI) for the region was 0.93. The highest CDI was in Tala (0.95) and the lowest in Dacope (0.42). The average cropping intensity (CI) of the Khulna region was 171% with the lowest in Mongla (101%) and the highest in Kalaroa (224%).Bangladesh Rice j. 2017, 21(2): 203-215

Delineating surface and sub surface waterlogged area using RS & GIS: a case study of Rachna Doab

Remote sensing (RS) combined with Geographical Information Systems (GIS) offers fabulous contrasting option to routine mapping strategies in observing and mapping of surface and sub-surface waterlogged areas. In the present study, a pre-monsoon and post-monsoon surface waterlogged area was delineated in the four districts of Rachna doab, using Landsat 8 data acquired for the year 2014. Modified Normalized Difference Water Index (MNDWI) was used mainly to delineate surface waterlogged areas. Perennial surface waterlogged areas were assessed for the study area by incorporating the waterlogged areas derived for both the pre-monsoon and post-monsoon seasons under GIS environment. Result shows that the total surface waterlogged area in pre-monsoon is 5,861 ha, which is 0.51 % of study area and for post-monsoon the surface waterlogging is 8,661 ha, which is 0.75% of study area respectively. Perennial surface waterlogging is 3,573 ha, which is 0.30% of the study area. Maximum waterlogged area was observed in Gujranwala district followed by Hafizabad, Sheikhupura and Nankana Sahib respectively. Further, waterlogged areas caused by rise in groundwater level were also assessed spatially under ArcGIS environment using the piezometric data pertaining of pre-monsoon and post-monsoon seasons for the year 2014 which were spread all over the study area. The analysis of both the seasons of groundwater levels indicates that the area under critical category during pre-monsoon period was 47,309 ha, which is 4% of the total area. Area under most critical category during post-monsoon period increased from 47,309 to 131,070 ha, which is 11% of the total. The study shows utility of remote sensing and GIS for evaluation of waterlogging areas especially where waterlogging situations occurs because of excessive irrigation and accumulation of rain and floodwater.

Effect of waterlogging on physical and mechanical properties of Samanea saman (Jacq.) Merr. tree

This research intends to explore the mechanical and physical properties of waterlogged rain tree (Samanea saman). The variation of mechanical and physical wood properties grown in waterlogged and non-waterlogged area were studied. Four trees of the species were selected from two areas. Important mechanical and physical properties were examined for the wood of two types of trees Oven dry density for the wood of waterlogged tree was 420 kg/m3 whether it was 550 kg/m3 for the wood of non-waterlogged tree. The MOR of wood of waterlogged tree was 58.2 N/mm2 and wood of non-waterlogged tree produced 78.1 N/mm2. The MOE of the wood of waterlogged tree and non-waterlogged tree were 1478 and 4876 N/mm2. The physical and mechanical properties were lower for the wood of waterlogged tree. Such findings may in proper uses of the species.Bangladesh J. Sci. Ind. Res. 52(1), 49-52, 2017