This study is descriptive in nature, which relies on both primary and secondary data sources. A comprehensive literature survey has done to investigate the causes of water logging problem in this region. The literature survey was also helpful to gain knowledge about human interventions undertaken to solve water logging problem in that region. The authors reviewed journals, books, newspapers, organizational reports and other published sources to perceive ideas on different issues of water logging. Study area selection: The study purposively selects Dumuria and Keshabpur Upazila of Khulna and Jessore district in South- western region of Bangladesh, as these areas have the long history of water logging. The study selects Latabonia and Dighalia villages under Shahos union of Dumuria upazila in Khulna district and Sagordari village under Sagordari union of Keshabpur upazilla in Jessore district.
Description of Dumuria Upazila: Total land area in Dumuria Upazila is 454.23 sq km, located in between 22°39´ and 22°56´ north latitudes and in between 89°15´ and 89°32´ east longitudes. It is bounded by Manirampur, Abhaynagar and Phultala upazilas on the north, Batiaghata and Paikgacha upazilas on the south, Khan Jahan Ali, Khalishpur and Sonadanga thanas and Batiaghata upazila on the east, Tala and Keshabpur upazilas on the west. Total population is 279862; male 144334, female 135528; Muslim 164126, Hindu 115245, Buddhist 264 and others 225. Main rivers are Shibsa and Singrail. Main sources of income are agriculture 65.43%, non-agricultural labourer 3.08%, commerce 14.05%, transport and communication 5.51%, service 5.54%, construction 0.88%, religious service 0.16%, rent and remittance 0.10% and others 5.25%. Main crops are paddy, jute, vegetables, and Main fruits are mango, jackfruit, coconut, betel nut.
Data Collection: The authors collect primary data during the period of September 2013 to December 2013. 20 semi-structured interviews were conducted for capturing the impact of water logging on plant growth, biodiversity and physical environment. The interviewees were mainly farmers and businessmen, who live in the study area for long time and thus would be able to capture the impact of water logging on biodiversity. In addition to this, five key informant interviews were conducted to get deep insight about changes in physical environment and changes in biodiversity and peoples’ adaptation to those changes in the study area. Key informant interview incorporates local peoples’ representative, local leader, local school teacher and one member of local water committee supported by one of the national NGOs Uttaran and another member from Water Development Forum formed by Bangladesh Water Development Board (BWDB). It was also necessary to collect data on the effect of water logging on plant growth, availability of birds, livestock, fish, fruit and timber trees etc. In order to gather data on these diversified issues, two FGD in Sagordari village and one FGD for each of Latabunia and Dighalia villages have done. After collection of all primary and secondary data, they were processed and analyzed to obtain the findings of the study.
IV. Impacts of Water logging on Biodiversity in the Study Area Biodiversity simply means the diversity, or variety of plants and animals and other living things in a particular area or region. Nature and extent of water logging significantly affects local biodiversity in the study area. Water logging reduces the availability of birds and fishes, restricts the opportunity to rear livestock. It restrains all sorts of plant growth, fruit trees and timber trees. Field survey shows that the scenario of whole physical environment has changed due to water logging.
V. Socio-economic Implication of Biodiversity Loss in the Study Area Field survey shows that severity and extent of water logging depends on condition of the adjacent river and existence and utilization of canals, which act as a connecting channel to discharge water from the locality. This study reveals that Sagordari village of Keshobpur Upazila is the utmost sufferer of water logging in terms of nature and severity of the problem. Kobadak river, which was full of tidal wave during 1970s and 1980s, gradually lost his power due to siltation of river beds and due to the flood during 2001-02. Now this river has completely died off, which causes a great suffering for the people of surrounding locality. These sufferings have been reflected in terms of biodiversity loss and resultant reduced well being.