**5. Salinity issue**

Soil salinity is one of the most common causes of soil degradation, which is getting worse day by day [7]. Usually soil salinity refers to surface or near-surface salt accumulation [8]. It is defined as the concentration of dissolved salts, mainly chlorides and sulfates, in soil or water [9]. It is practically expressed as practical salinity unit (PSU) which depends on the water temperature and conductivity [10]. It is also expressed as ppt (parts per thousand). The characterization of soil salinity is normally done by spectrometer through measuring the electric conductivity (EC) in a saturated soil paste or in aqueous extracts with different soil/water ratios [11].

**27**

**Bangladesh**

*Frequent Change of Land-Use Pattern and Its Effect on Ecology and Ecosystem in the South-West…*

Out of 2.85 million hectares of the coastal and offshore lands, about 1.05 million hectares of arable lands are affected by varying degrees of salinity [6]. From another

(more than 8 dS/m), indicating 43% of the total salt-affected areas are facing challenges for agricultural practices even with salt-tolerant rice varieties [12]. Huge economic loss, damage to rice crops, and difficulties in drinking water supply systems in many villages

Salinity is one of the most significant problems in the South-West coastal belt which is denoted as a food-deficit area of Bangladesh. Both the diversity of food and the net food production have declined significantly over the last decades [13]. It is reported that the worst salinity conditions are found in Khulna, Bagerhat, Satkhira, and Patuakhali districts [12]. Around 70% of the land in Barisal and

Generally salinity can develop naturally (primary salinity), but human interference accelerated the movement of salts into rivers and onto land (secondary salinity). The spatial inconsistency of soil salinity over the landscape is highly sensitive and controlled by a variety of factors: soil factors (parent material, permeability, depth of water table, groundwater quality, and topography), management factors (irrigation and drainage), and climatic factors (rainfall, temperature, and humidity) [15]. Hence it is difficult to assess human interference on land salinity

Secondary salinity is mostly related to inequitable exploitation of natural resources, global climate change, and land-use changes, such as overgrazing and excessive utilization of land and water resources [17]. Land-use changes disturb hydrologic conditions which in turn alter the land salinity pattern of the area [18]. Thus poor land and water management system in irrigated farmlands leads to secondary salinity worldwide [19]. Bangladesh is one of the most vulnerable countries in salinity issue. The major causes of saline intrusion in water and soil include cyclone and storm surge, sea level rise, and shrimp farming practices [5]. Thus, shrimp farming is one of the

**6. How shrimp farming influences the economy and LULC in the coastal** 

Shrimp industry is mostly concentrated in tropical developing countries making shrimps as a major export item for the Western countries [20]. This industry has experienced amazing growth over the last decades [13]. In the Asia-Pacific region, it

Shrimp farming plays an important tool for poverty reduction and livelihood improvement for some households, but it has an adverse impact on coastal environment [22, 23], particularly in Southeast Asia. Two major environmental impacts of shrimp culture are the consumption of resources and the subsequent release of wastes into the environment [24, 25]. Other impacts include reduced water flow, soil salinization, diminution and salinization of ground- and surface water, depletion of wild fish and shrimp populations, extinction of wild vegetation, and biological pollution of native shrimp stocks [20, 22, 23]. The topsoil (0–20 cm) of

in 1973 to

is affected by a higher level of salinity

study, it is found that the salinity-affected area has increased from 8330 km2

of the coastal districts are the common problems caused by salinity [5].

Khulna divisions was affected by different degrees of salinity [14].

separately as it is highly integrated with environmental complexity [16].

*DOI: http://dx.doi.org/10.5772/intechopen.92806*

10,560 km2

**5.1 Soil salinity situation in the coast of Bangladesh**

in 2009, of which about 4530 km2

**5.2 Major causes of salinity in the coastal area**

major causes of secondary salinity in Bangladesh.

is one of the highest growing economic activities [21].

*Frequent Change of Land-Use Pattern and Its Effect on Ecology and Ecosystem in the South-West… DOI: http://dx.doi.org/10.5772/intechopen.92806*

### **5.1 Soil salinity situation in the coast of Bangladesh**

*Landscape Architecture - Processes and Practices Towards Sustainable Development*

fields, pastures, and managed woods.

**4. Importance of coastal Bangladesh**

cyclones, drought, and saltwater intrusion [5].

**4.2 Agriculture in the coastal area of Bangladesh**

**3. LULC change (LULCC)**

**4.1 The coast of Bangladesh**

other agricultural lands.

**5. Salinity issue**

such as forest, vegetation, open water, bare soil, etc. Land-use includes the management and modification of natural environment or wilderness into manufactured environment, for example, settlements and seminatural habitats like productive

Land-use and land cover change (LULCC) is the conversion of different types of land-use and is the result of complex interactions between humans and the physical environment. LULCC might be a major driver of global alteration and has a consid-

Bangladesh coast consists of 19 districts which cover 32% of the total area of the country [1]. The population in the coastal area is expected to increase from 36.8 million in 2001 to 60.8 million by 2050 [2]. This coastal belt has miscellaneous natural resources counting the largest mangrove forest in the world (Sundarbans), salt, coastal fisheries, and other minerals. Additionally, this part of the country has a high exploration prospective for both onshore and offshore natural gas [3]. The resourceful ecosystems of this coastal area maintain the livelihoods of the local communities. Moreover, this region has the potential for tourism, ports, and other developments [4]. But this region is highly exposed to various climatic factors, such as temperature fluctuation, erratic behavior of rainfall, increased frequency of

Agriculture is the major sector in the economy of Bangladesh, and over 30% of the net cultivable land is in the coastal area [6]. In the past, people were interested to cultivate not only local varieties that are saline tolerant but also other varieties with greater plant height and comparatively low production cost and are tasty and above all easily manageable. The local rice varieties are categorized into two types, one for planting in the freshwater shrimp farms and another for other agricultural lands. *Jotabalam* and *ghunshi* varieties are selected to be cultivated in the shrimp farms. On the other hand, *ashfall* and *benapol* varieties are designed for planting in

Soil salinity is one of the most common causes of soil degradation, which is getting worse day by day [7]. Usually soil salinity refers to surface or near-surface salt accumulation [8]. It is defined as the concentration of dissolved salts, mainly chlorides and sulfates, in soil or water [9]. It is practically expressed as practical salinity unit (PSU) which depends on the water temperature and conductivity [10]. It is also expressed as ppt (parts per thousand). The characterization of soil salinity is normally done by spectrometer through measuring the electric conductivity (EC) in a saturated soil paste or in aqueous extracts with different soil/water ratios [11].

erable impact on ecosystem processes, biological cycles, and biodiversity.

**26**

Out of 2.85 million hectares of the coastal and offshore lands, about 1.05 million hectares of arable lands are affected by varying degrees of salinity [6]. From another study, it is found that the salinity-affected area has increased from 8330 km2 in 1973 to 10,560 km2 in 2009, of which about 4530 km2 is affected by a higher level of salinity (more than 8 dS/m), indicating 43% of the total salt-affected areas are facing challenges for agricultural practices even with salt-tolerant rice varieties [12]. Huge economic loss, damage to rice crops, and difficulties in drinking water supply systems in many villages of the coastal districts are the common problems caused by salinity [5].

Salinity is one of the most significant problems in the South-West coastal belt which is denoted as a food-deficit area of Bangladesh. Both the diversity of food and the net food production have declined significantly over the last decades [13]. It is reported that the worst salinity conditions are found in Khulna, Bagerhat, Satkhira, and Patuakhali districts [12]. Around 70% of the land in Barisal and Khulna divisions was affected by different degrees of salinity [14].

### **5.2 Major causes of salinity in the coastal area**

Generally salinity can develop naturally (primary salinity), but human interference accelerated the movement of salts into rivers and onto land (secondary salinity). The spatial inconsistency of soil salinity over the landscape is highly sensitive and controlled by a variety of factors: soil factors (parent material, permeability, depth of water table, groundwater quality, and topography), management factors (irrigation and drainage), and climatic factors (rainfall, temperature, and humidity) [15]. Hence it is difficult to assess human interference on land salinity separately as it is highly integrated with environmental complexity [16].

Secondary salinity is mostly related to inequitable exploitation of natural resources, global climate change, and land-use changes, such as overgrazing and excessive utilization of land and water resources [17]. Land-use changes disturb hydrologic conditions which in turn alter the land salinity pattern of the area [18]. Thus poor land and water management system in irrigated farmlands leads to secondary salinity worldwide [19].

Bangladesh is one of the most vulnerable countries in salinity issue. The major causes of saline intrusion in water and soil include cyclone and storm surge, sea level rise, and shrimp farming practices [5]. Thus, shrimp farming is one of the major causes of secondary salinity in Bangladesh.

### **6. How shrimp farming influences the economy and LULC in the coastal Bangladesh**

Shrimp industry is mostly concentrated in tropical developing countries making shrimps as a major export item for the Western countries [20]. This industry has experienced amazing growth over the last decades [13]. In the Asia-Pacific region, it is one of the highest growing economic activities [21].

Shrimp farming plays an important tool for poverty reduction and livelihood improvement for some households, but it has an adverse impact on coastal environment [22, 23], particularly in Southeast Asia. Two major environmental impacts of shrimp culture are the consumption of resources and the subsequent release of wastes into the environment [24, 25]. Other impacts include reduced water flow, soil salinization, diminution and salinization of ground- and surface water, depletion of wild fish and shrimp populations, extinction of wild vegetation, and biological pollution of native shrimp stocks [20, 22, 23]. The topsoil (0–20 cm) of

the shrimp ponds are mostly affected by salinity, and it is decreasing further inland [26]. In Asia, shrimp farming has been far away from success as the industry claims, especially when environmental costs are internalized [27].

Shrimp is denoted as the "golden price" in Bangladesh, because of its valuation in the international market. Shrimp production got the position as the second largest export business in Bangladesh by earning US\$456 million in 2006 [28]. The fisheries' part, together with shrimp, contributes about 6% of the GDP and 5% of the national export earnings, with shrimp alone contributing about 93% of the sectoral export earnings [29]. This enlighten why the coastal areas were declared as a "free zone" for shrimp cultivation in 1994 by the Bangladesh government [30]. Subsequently, shrimp cultivation extended noticeably. In favor of example, shrimp was cultivated on 39% of the land of the Shyamnagar *Upazila* (subdistrict) of Satkhira District in 2002. It had enlarged to 57 and 62% by 2007 and 2011, respectively [13]. It is also reported in a recent analysis that 83% of the paddy field of 1988 was converted to different other land-use type in 2017, of which 23% is converted to water bodies [31].
