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Impacts of Salinity, Arsenic, and Drought in Southwestern Bangladesh

M. A. Abedin
Department of Soil Science, Bangladesh Agricultural University (BAU)

Umma Habiba
Department of Soil Science, Bangladesh Agricultural University (BAU)

Rajib Shaw
Keio University, Keidai, Graduate School of Media and Governance, Doctor of Science

Abstract/ Executive Summary:

The southwest area lies between 21º30’ and 23º15’ north and 89º00’ and 90º00’ east and includes the world’s largest continuous mangrove forest, the Sundarbans, as well as estuarine marshlands and numerous rivers, canals, and their tributaries (Giri & Shrestha, 1996; Viju, 1995). It covers an area of 26,200 km² and has a population of 18.3 million. It is divided roughly into coastal and inland areas. The terrain is relatively flat; the elevation ranges from sea level to 5.0 m above mean sea level (Castro-Ortiz, 1994). Approximately 85% of the people of this region depend on agriculture; landless farmers make up almost 66% of population. Fishing, agriculture, shrimp farming, salt farming, and tourism are the area’s main economic activities. The southwest region – especially Satkhira, Bagerhat, Khulna, and Jessore – experience extreme inland saline-water intrusions, and agricultural crop fields gradually experience this salinity increase. Another hazardous problem is severe arsenic contamination in groundwater. In recent times, arsenic in tube-well waters has so upset drinking-water supplies that it became a national health issue. The groundwater is contaminated by arsenic in a large area, mainly around major rivers in this region. Similarly, the silent, invisible disaster drought appears in this region. The average annual rainfall in this area is approximately 1,700 mm, and the rainfall of the district along the border with India at the west is fairly low. Severely decreased Ganges water discharge along with the river’s low flow rate in the dry season causes drought in this area and damage to the mangrove forest. Furthermore, the presence of Farakka Dam on the upper Ganges River and depleted groundwater, this region is more prone to drought and designated as a moderate drought-prone area in Bangladesh. But sinking groundwater tables are more frequently observed in Kushtia and Jessore districts. The high-salinity, high-arsenic, and drought-prone areas of southwestern Bangladesh are represented.

Keywords: Natural hazard, Southwestern part, Overall impact, Appropriate future strategies, Soil salinity, Arsenic, Drought

Location: Satkhira, Bagerhat, Khulna, and Jessore district, Bangladesh

Start Date:

End Date:

Program Area: Risk Management in Agriculture

Commodity: Soil salinity, Drought, Water Arsenic

Objectives:

To explore the current situation of the previously mentioned natural hazards in the southwestern part of the country, their pertinent underlying causes, overall impacts and interrelationship among these natural hazards, and appropriate future strategies for effectively overcoming these conditions.

Methodology:

In 1974, India built the Farakka Barrage, diverting water from the upper sections of the Ganges River and into the Hugli River (Gain, Aryal, Sana, & Uddin, 2007). The effects downstream in Bangladesh included a significantly decreased water supply, which led to increased intrusions of seawater into the Ganges River basin and eventually increased river and groundwater salinity (Gain et al., 2007; Shamsuddin, Xiaoyong, & Hazarika, 2006). Salts enter the soil through tidal flooding during the wet season (June to October), by direct inundation of saline or brackish water, and by upward movement of saline groundwater in the dry season (November to May) (Dutta & Iftekhar, 2004; Fleming, 2004; Haque, Bhatta, Hoque, Rony, & Rahman, 2008). Industrial shrimp cultivation is one prime reason why this high-salinity area is increasing and intensifying over time. The rapid expansion of shrimp farms during the last decade, along with the adoption of extensive and improved farming techniques, is partly responsible. As sea level continues to raise, the associated effects of permanent inundation are likely to increase salinity near coastal areas. A recent study shows that 5 ppt saline front will penetrate about 40 km inland for SLR of 88 cm, which will affect only the freshwater pocket of Tetulia River in Meghna Estuary. Salinity ingress causes an increase in soil salinity, especially when farmers irrigate their lands at the beginning of the low flow period. The Soil Resources Development Institute (SRDI) (1997) reported that soil salinity levels south of the towns of Khulna and Bagerhat ranged between 8 and 15 dS/m during the low flow season. In Bangladesh, annual and seasonal temperatures generally show increasing trends. Moreover, the General Circulation Model/Global Climate Model (GCM) outputs provided by MAGICC/SCENGEN for the southwestern region of Bangladesh shows that the average increase of temperature would be 0.88⁰1C and 2.42⁰1C for the years 2030 and 2075, respectively. Bangladesh belongs to subtropical regions where monsoon weather prevails throughout the year. At the national level, about 80% of the annual rainfall occurs during July–October, and almost no rain falls during winter (October–May) (Hussain et al., 1987).

Source of Information: Community, Environment and Disaster Risk Management, Volume 9, 165–193; ISSN: 2040-7262

Article Link (Online Journal): doi:10.1108/S2040-7262(2012)0000009016

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The findings of this study provide a detailed overview of various types and intensities of natural hazards faced by different communities in southwestern Bangladesh as represented by three selected measures: increased salinity, arsenic contamination, and drought. All of these natural hazards have multiple impacts on communities, decreasing their survivability and increasing their vulnerabilities to future events. Moreover, according to IPCC (2007), the effect of climate change on surface and groundwater resources in Bangladesh will be entirely negative. From the study, it is clear that the southwestern region faces water-related problems from too much water in monsoon season (leading to flooding) and too little water in dry season (leading to drought). People in this area depend on surface water for fish cultivation, navigation, and industrial and other uses, and they use groundwater for domestic and irrigation purposes, so the presence of saline and arsenic in water – along with water scarcity during the dry season – means that the lack of safe drinking water and irrigation water ultimately hampers their daily lives. Last but not least, it can be concluded that this community-based integrated approach will be effective for the community, by which people can adapt with the upcoming events in the near future in a sustainable way.

Knowledge Management: Journal