Journal of Environmental Management 161 (2015) 443e452

Contents lists available at ScienceDirect

Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman

Implications of agricultural land use change to ecosystem services in the Ganges delta G.M. Tarekul Islam a, *, A.K.M. Saiful Islam a, Ahsan Azhar Shopan a, Md Munsur Rahman a,  za r b, Anirban Mukhopadhyay c Attila N. La a b c

Institute of Water and Flood Management, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh Civil, Maritime and Environmental Engineering and Science Unit, Engineering and the Environment, University of Southampton, UK School of Oceanographic Studies, Jadavpur University, India

a r t i c l e i n f o

a b s t r a c t

Article history: Received 24 July 2013 Received in revised form 27 October 2014 Accepted 18 November 2014 Available online 13 December 2014

Ecosystems provide the basis for human civilization and natural capital for green economy and sustainable development. Ecosystem services may range from crops, fish, freshwater to those that are harder to see such as erosion regulation, carbon sequestration, and pest control. Land use changes have been identified as the main sources of coastal and marine pollution in Bangladesh. This paper explores the temporal variation of agricultural land use change and its implications with ecosystem services in the Ganges delta. With time agricultural lands have been decreased and wetlands have been increased at a very high rate mainly due to the growing popularity of saltwater shrimp farming. In a span of 28 years, the agricultural lands have been reduced by approximately 50%, while the wetlands have been increased by over 500%. A large portion (nearly 40%) of the study area is covered by the Sundarbans which remained almost constant which can be attributed to the strict regulatory intervention to preserve the Sundarbans. The settlement & others land use type has also been increased to nearly 5%. There is a gradual uptrend of shrimp and fish production in the study area. The findings suggest that there are significant linkages between agricultural land use change and ecosystem services in the Ganges delta in Bangladesh. The continuous decline of agricultural land (due to salinization) and an increase of wetland have been attributed to the conversion of agricultural land into shrimp farming in the study area. Such land use change requires significant capital, therefore, only investors and wealthier land owners can get the higher profit from the land conversion while the poor people is left with the environmental consequences that affect their long-term lives and livelihood. An environmental management plan is proposed for sustainable land use in the Ganges delta in Bangladesh. © 2014 Elsevier Ltd. All rights reserved.

Keywords: Agriculture Land use Ecosystem Ganges Delta

1. Introduction The agricultural sector of Bangladesh contributes to 19.29% of GDP. It dominates both land use and the national economy. It supports people's lives and livelihood in this region. The performance of agricultural production has an overwhelming impact on major macroeconomic objectives like employment generation, poverty alleviation, human resources development and food security. However, gradual increase of population, urbanization,

* Corresponding author. Tel.: þ88 01748293411. E-mail addresses: [email protected] (G.M.T. Islam), [email protected]. ac.bd (A.K.M.S. Islam), [email protected] (A.A. Shopan), mmrahman@ za r), anirban_iirs@ iwfm.buet.ac.bd (M.M. Rahman), [email protected] (A.N. La yahoo.com (A. Mukhopadhyay). http://dx.doi.org/10.1016/j.jenvman.2014.11.018 0301-4797/© 2014 Elsevier Ltd. All rights reserved.

industrialization and soil salinization have caused significant reduction of agricultural land particularly the croplands over the last few decades. Land use in Bangladesh is determined mainly by the monsoon climate and the seasonal flooding which affects the greater part of the country. These physical determinants are reinforced by high population pressure and, increasingly, by anthropogenic changes in the natural environment through flood protection, drainage and irrigation developments. Many studies have been conducted to assess land use change and drivers causing the change. Lambin and Ehrlich (1997) studied land cover change in the African continent during the time period from January 1982 to December 1991. They concluded that although vegetation changes in land cover were found to be just a fraction of the total change detected in land cover, their effect on ecosystems and sustainability of livelihood might be significant. Johnson and Kasischke (1998)

444

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

discussed change vector analysis: a technique for the multispectral monitoring of land cover and condition. Liu et al. (2005) explored change of cropland across China for the time period of 1990e2000. Jabbar et al. (2006) applied a computerized parametric methodology to monitor, map, and estimate vegetation change in the Letianxi Watershed of western Hubei Province, China. Landsat TM 1997 and Landsat ETM 2002 and thematic maps were used to provide comprehensive views of surface conditions such as vegetation cover and land use change. It was found that 60.9% of land area had very slight to slight vegetation change, while 39.1% had moderate to severe vegetation change. Some studies have identified that transformation of agricultural lands into shrimp farms changed land use and land cover of coastal areas (Dewalt et al., 1996; Flaherty et al., 1999; Ali, 2006). Land use changes have been identified as the main sources of coastal and marine pollution in Bangladesh (DoE, 2003). The farmers in Satkhira-BagerhatKhulna area have switched over to shrimp culture from traditional agriculture, allowing more and more salt-water in the land. There are 37,400 bagda (saltwater shrimp) fields with an operated area of 170,000 ha (WARPO, 2003). Changes in land use impact both environmental quality and the quality of life. According to the Millennium Ecosystem Assessment (2005), human activity is having a significant and escalating impact on the biodiversity of world ecosystems, reducing both the irresilience and bio-capacity. Human activities have changed ecosystems more rapidly and extensively in the last 50 years and even more rapid and extensive changes projected for the next half century and beyond (Millennium Ecosystem Assessment, 2005). Ecosystem services are components of nature which include resources such as surface waters, oceans, soils, flora and fauna, etc. The ecosystem services of river deltas often support high population densities. A large proportion of delta populations experience extremes of poverty and are highly vulnerable to the environmental and ecological stress. For many of the poor, who have little or no access to land, their primary asset remains their labor and whether they are engaged in agricultural laboring or in the non-farm sector they continue to be marginalized from the development process (Toufique and Turton, 2002). Finding the relationship between ecosystem services and poverty alleviation is vital if resources are to be used sustainably and to alleviate poverty (Chaudhury, 2008). Certain changes (i.e. adaptation) are necessary as people in the coastal zone of Bangladesh face multiple threats (extreme poverty, food insecurity due to population increase, sea level rise, salinization, cyclones, etc.). Ecosystems form the life-supporting system of the Earth. It provides the basis for human civilization and natural capital for green economy and sustainable development. Ecosystem services may range from crops, fish, freshwater to those that are harder to see such as erosion regulation, carbon sequestration, and pest control. Ecosystem services are getting attention to the environmental community for conservation missions because the protection of ecosystem services is vital in securing the long-term livelihood of people. It has been felt that a study on existing land use, current potential growth of different sectors and availability of land for future infrastructural development is necessary (DoE, 2003). This study assesses the change in agricultural land use in the Ganges delta and its implications with ecosystem services. The difference between the aforementioned studies and the current study is that our study establishes and quantifies the linkages between agricultural land use change and ecosystem services and henceforth explores the implications of such changes in the Ganges delta. In addition, the paper proposes an environmental management plan for sustainable land use in the Ganges delta in Bangladesh. This might help policy makers and implementing agencies to avoid unplanned change of land use that may degrade ecosystem.

2. Ganges delta The Ganges delta, also known as the Ganges and Brahmaputra delta, is one of the largest deltas in the world (Fig. 1). It is a river delta consisting of Bangladesh and the state of West Bengal, India. The Ganges delta covers an area of more than 105,000 km2, and has a 350 km long shoreline along the Bay of Bengal. The delta was formed during the last 11,000 years within the large foredeep, i.e., the Bengal basin (Mikhailov and Dotsenko, 2006). The hydrographic system of the delta consists of three deltaic channel systems: the Ganges and Brahmaputra channel systems and the combined channel system formed as a result of their confluence. The main branches of these three channel systems are the Ganges, the Jamuna and the PadmaeLower Meghna. The Ganges Delta lies mostly in the tropical wet climate zone, and receives between 1500 and 2000 mm of rainfall each year in the western part, and 2000e3000 mm in the eastern part (Islam and Gnauck, 2008). This rainwater combined with large quantities of water flowing down the Ganges and Brahmaputra rivers provide sufficient freshwaters for a productive agriculture in coastal Bangladesh. The Ganges delta inside Bangladesh covers an area of 40,450 km2 which is approximately 27% of the total area of Bangladesh (Islam and Jaman, 2006). This vast area is inhabited by about one fourth of country's population of about 160 million. More than 60% of the area is under cultivation. This deltaic region is unique in many ways. The Sundarbans, the single largest mangrove forest in the world, is located in this region spanning an area equal to about 10% of Bangladesh that has extensive biodiversity-based economic activities (e.g. honey and fruit collection) and potential for eco-tourism. The Sundarbans has an outstanding importance for being World Heritage Site and Ramsar Site. The delta has a distinctive landscape feature that it is criss-crossed by a network of rivers and estuaries together with extensive floodplains and wetlands. These surface water bodies cover 13% of the delta plain. The country is located in the Bengal Basin, which has been gradually filled by alluvial sediment washed down from the highlands of the Himalayas. The basin has become a low lying flat delta. The soil series of Bangladesh according to the US soil taxonomy, fit into five orders viz. inceptisols, entisols, ultisols, histosols and mollisols. The soil types in the southwest region of Bangladesh are entisols (the whole of the Sundarbans and the southern part of our study area), inceptisols (northern part of the study area) and histosols (a very minor portion of the study area, at the north-east corner of Bagerhat). The soil has large amounts of minerals and nutrients, which is good for agriculture. This has made the delta one of the most fertile regions in the world. Pollution, human encroachment, soil erosion and rising sea levels threaten to submerge large parts of the delta into the sea. An increase of half a meter in sea level could result in six million people losing their homes in Bangladesh. 3. Ecosystem and ecosystem services in the Ganges delta Millennium Ecosystem Assessment (2005) defines ecosystem services as benefits people obtain from ecosystems. Ecosystem services are components of nature. Ecosystem components include resources such as surface waters, oceans, soils, flora and fauna, etc. Ecosystem process and functions are the biological, chemical and physical interactions between ecosystem components (Boyd and Banzhaf, 2006). Ecosystems provide four types of potential services such as supporting services, provisioning services, regulating services, and cultural services. The ecosystem services are now under threat due to anthropogenic influences and climate change impacts on natural resources. Ecosystems management and biodiversity conservation plays a critical role in response to climate

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

445

Fig. 1. Location of the Ganges delta inside Bangladesh.

change impacts, especially in increasing the resilience of vulnerable ecosystems and using ecosystem services, such as ecosystem-based adaptation. Almost half of the world's wetlands have been destroyed in the past 100 years (Barbier, 1993). Sultana et al. (2009) showed that more than 50% of the wetland area in Dhaka city reduced over the period 1968 to 2001 due to urbanization. In Bangladesh, 45% of mangrove wetlands have already been destroyed due to shrimp farming and anthropogenic influences (Khan et al., 1994). Thus ecosystems management and biodiversity conservation play a critical role in response to climate change impacts. This will increase the resilience of vulnerable ecosystems. Delta regions are the most vulnerable type of coastal environment because their ecosystem services face multiple stresses. These stresses include local drivers due to land subsidence, population growth and urbanization within the deltas, regional drivers due to changes in catchment management, and global climate change impacts such as sea-level rise. Important ecosystem services in the study area are agricultural lands and wetlands which support fisheries resources and the Sundarbans mangrove forest. Major fish sources in the study area are the rivers, floodplains, ponds, beels (depressions), baors (oxbow lakes) and the shrimp farms. In this study, the catch/production of fish from rivers are not considered, because the primary aim of this research paper is to compare the land cover and production changes of agricultural lands and wetlands. 4. Study area The study area covers the Khulna division of Bangladesh within the Ganges delta. It lies between latitudes 21390 000 N to 23 050 000 N and longitudes 88 540 000 E to 90 000 000 E. It is the southwest region of Bangladesh and includes three districts of Khulna division e Satkhira, Khulna and Bagerhat. The Sundarbans, the world's largest mangrove forest lies in the southern part of the

study area. Khulna district has an area of 4394 km2. It is one of the important industrial and commercial areas of the country. 75% of shrimp exported from Bangladesh are cultivated in the Khulna zone. It is also known for its lobster, prawn, catfish, and crab. Satkhira district has an area of 3858 km2;. The total population of Satkhira district is 1,843,194. Most of the peoples of southern part of Satkhira depend on pisciculture. The main exports are shrimp, paddy, jute, wheat, betel leaf, leather and jute goods. Bagerhat district has a total area of 3959 km2. Rampal and Fakirhat - two Upazillas of Bagerhat, is known for its huge production of shrimp. 5. Data and methodology The study used satellite images and secondary data (rice cultivated area, shrimp and fish production) collated from national agencies such as Bangladesh Bureau of Statistics and Department of Fisheries, Bangladesh. In order to assess the land cover and land use change pattern in the study area, four Landsat scenes of 1980, 1989, 1999 and 2008 are used. The images have been downloaded from webpage of United States Geological Survey (www.earthexplorer. usgs.gov). These images are taken at four tiles: Path of 137 with Row of 44, Path of 137 with Row of 45, Path of 138 with Row of 44 and Path of 138 with Row of 45, which cover the entire study area. The images represent dry season of Bangladesh as they have been captured in November to January period. It is assumed that temporal changes of water bodies remain insignificant over this period. Properties of the images are presented in Table 1. It should be mentioned that the TM (Thematic Mapper) sensor has a spatial resolution of 30 m for the visible, near-IR, and mid-IR wavelengths and a spatial resolution of 120 m for the thermal-IR band. The ETMþ (Enhanced Thematic Mapper Plus) has spectral bands which are similar to those of TM, except that the thermal band (band 6) has an improved resolution of 60 m (versus 120 m in TM). The level 1G/1T processed images are resampled to 30 m resolution.

446

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

Open source software, Integrated Land and Water Information System (ILWIS, 2012) has been used to process the Landsat images and conduct spatial analysis. Land cover and land use classification using satellite image analysis includes several steps such as image importing, image gluing, sub setting, sample set preparation, supervised classification etc. While preparing the land use map for any particular year, firstly, the downloaded images of band 2, band 4 and band 7 from different tiles were imported individually. For each of these bands, images of the particular band at different tiles were glued to prepare a mosaic of the tiles. The combined image covers the entire study area. However, it also had portions beyond the study area. Thus, a sub-map was created which only contained the study area. In total three such maps (one for each of the bands 2, 4 and 7) were prepared. These images of band 2, 4 and 7 were used in the later part of land use mapping. The 7, 4, 2 combination was used for land use classification (3, 2, 1 combination in case of 1980 image). Four types of land use were considered. These are: (1) Agricultural lands, (2) Forestry, (3) Wetlands and (4) Settlement & others. A sample set was prepared using the same band combination and a reasonable number of pixels in the sample set were used for training each of the land use categories selected. The sample set was then used for supervised classification of land use in the study area. The classification technique used was maximum likelihood classification algorithm. A land use map of the study area for the particular year was obtained in the process where the study area was classified into the four land use categories selected earlier. In the classification process, agricultural lands typically included croplands and fallow lands. Forestry primarily included the Sundarbans. As the houses and road networks in the study area are typically surrounded by large trees, in this study, forestry excluding the Sundarbans was considered as rural settlements and road networks. Settlement & others primarily included urban settlements and barren lands. But the area of rural settlements and road network were also added up to Settlement & others. This combined area of urban, rural, barren land and road network has been considered as the settlement & others land use category in this study. Wetlands primarily included shrimp farms, ponds, rivers and the Bay of Bengal. However, rivers and the Bay of Bengal are not among wetlands. In order to exclude the rivers and the Bay of Bengal, a shape file of rivers in Bangladesh was used. Because the river shape file had some inaccuracies, parts of some rivers were still present in the image alongside the wetlands. These river pixels were also removed. Thus the land cover category ‘wetlands’ was left only with shrimp farms and ponds. Land use and land cover pattern was determined by extracting data from satellite image analysis at each of the selected years. 6. Assessment of agricultural land use change The main focus of the study is to assess the agricultural land use change and its implications with ecosystem services, therefore, only the agricultural land use change is mapped. However, the temporal variations of all other land use types have been quantified. The overall accuracy of the classification has been determined by using ground truthing, knowledge based judgment and field survey which was followed by developing a confusion matrix for accuracy

Table 1 Properties of Landsat satellite images. Image no.

Acquisition date

Satellite

1 2 3 4

January, 1980 January, 1989 November, 1999 November, 2008

Landsat Landsat Landsat Landsat

3 4 7 5

Sensor

Spatial resolution (m)

MSS TM ETMþ TM

60 30 30 30

assessment. The spatial distribution of the ground truthing points is shown in Fig. 2 while the accuracy assessment is shown in Table 2. A total of 200 ground truthing points are used for accuracy assessment. The overall accuracy of classification is expressed as percentage of classified land use against actual land use. The accuracy of the classification as found from confusion matrix is over 90%. This has been done for the latest image. However, such analyses were not possible for imageries of earlier date, owing to the lack of information pertaining to that period. However, it is assumed that the same accuracy of classification could be expected for classification of earlier images. The agricultural land use change is shown in Fig. 3 and the temporal variations of all other land use types have been presented in Fig. 4. It is noted that agricultural land is meant to be cropland only. It can be clearly seen from Figs. 3 and 4 that the agricultural land use in the study area has been gradually declined since 1980. The area of wetlands was very small in 1980. However, at the same time when the extent of the agricultural lands has been decreased, wetland areas have been expanded at a very high rate mainly due to the growing popularity of shrimp farming. It has been found that in 2008, wetlands cover more area than agricultural lands in the study area. In a span of 28 years, the agricultural land has been reduced by approximately 50%, while the wetlands have been increased by over 500%. It can be noticed that in 2008 the area of agricultural land is even lower than the settlement area. This reduction of agricultural lands in 2008 can be partly attributed to the fact that cyclone Sidr that happened in November 2007 breached the polders and flooded large areas of agricultural lands with salty waters. Unfortunately, the agriculture production in these areas still has not returned to normal due to the salinization of soils. A transformation matrix has been developed between 1989 and 2008 as shown in Table 3. As the study area is criss-crossed by numerous rivers especially in the Sundarbans region, there has been a significant amount of land erosion and land accretion over the period of 19 years. This also contributed to the transformation of land use and land cover in the study area. It has been found that about 54% of the wetlands in 2008 has been converted from agricultural lands present at 1989. Another 21% has been converted from settlement & others land type present at 1989. Again, about 18% of wetlands present at 1989 has been converted to agricultural lands in 2008. Whereas, approximately 35% of settlement & others land type present at 1989 has been transformed into agricultural lands by the year 2008. Thus it is clear that the major contributor to the rapid increase in wetlands is the conversion of agricultural lands. The transformation of land use and land cover change between 1989 and 2008 has been overlaid as can be seen in Fig. 5. It should be mentioned that the climatic variation in this time (1980e2008) is not responsible for land use change in these regions. The temporal variation of precipitation and maximum temperature in the study area during 1980e2008 have been studied. Figs. 6 and 7 below show the temporal variation of precipitation and maximum temperature measured by Bangladesh Meteorological Department in the study area during 1980e2008, respectively. Statistical trend tests have been performed to identify if there exits any significant trend in the precipitation and maximum temperature. The results of the analysis are shown in Table 4. As can be seen from Table 4 that there is no significant trend at 5% level of significance for precipitation and maximum temperature in the study area. This implies that the change in land use is only due to anthropogenic cause. Lambin and Ehrlich (1997) used NOAA's advanced very high resolution radiometer to detect land cover change in the African continent during the time period from January 1982 to December 1991. The study demonstrated that inter-annual land cover changes

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

447

Fig. 2. Map showing the spatial distribution of the ground truthing points.

in Africa mostly involve erratic variations in land-cover conditions due to inter-annual climatic variability and temporary modifications in seasonality. Liu et al. (2005) used Landsat TM/ETM data to estimate change in cropland across China for the time period of 1990e2000 and found that the urbanization accounted for more than half of the transformation from cropland to other land uses, and the increase in cropland was primarily due to reclamation of grassland and deforestation. The globalization as well as changing environment in China affected land-use change. This is in contrast to the present study where the change in agricultural land use is attributed to the conversion of agricultural lands into shrimp farming. This demonstrates that the drivers of land use change vary from one region to another. A large portion (nearly 40%) of the study area is covered by the Sundarbans. The area of Sundarbans mangrove forest remained almost constant which can be attributed to the strict regulatory intervention to preserve the Sundarbans. The rest of the area was

covered mostly by agricultural lands, wetlands, settlement and others. The settlement & others land use type has also been increased to nearly 5%. The findings are in contrast to the study of SRDI (2012) that investigated the trends in the availability of agricultural lands in Bangladesh. The SRDI study found that area under agriculture was 9.76 million hectare in 1976, which decreased to 9.44 million hectare in 2000, which was further decreased to 8.75 million hectare in 2010. However, the decline of agricultural lands based on our remote sensing study is more severe than the national (declining) trend of agricultural lands of the SRDI study. 7. Implications of agricultural land use change to ecosystem services It was found earlier that agricultural lands have been reduced while the wetlands have been increased. Agricultural lands are mainly used for rice cultivation. Rice is the main crop produced in

Table 2 Confusion matrix for assessing accuracy of land use classification.

Classification

Class Agricultural land Sundarbans Wetlands Settlement & others Total Producer's accuracy % Overall accuracy

Reference Agricultural land 46 1 2 1 50 92% 90%

Sundarbans 2 47 1 0 50 94%

Wetlands 4 0 44 2 50 88%

Settlement & others 3 0 4 43 50 86%

Total 55 48 51 46 200

User's accuracy % 84% 98% 86% 93%

448

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

Fig. 3. Spatial coverage of agricultural lands in the study area for different years.

the study area. There are three varieties of rice in the study area viz. Aus, Aman and Boro. The temporal variation of rice cropland is shown in Fig. 8. It is found from Fig. 8 that the total area of rice production is in a decreasing trend since 1990's and in our study area it has lost its dominant status. Fig. 9 shows the temporal change of shrimp and fish production in the study area. Usually shrimp farms produce fish along with shrimp. It is found from Fig. 9 that there is a gradual upward trend of shrimp and fish production in the study area. The increase of

wetlands and decrease of agricultural lands are attributed to the fact that the agricultural lands have been converted into shrimp farms in the study area. The conversion of agricultural and into shrimp farming and their environmental and ecological concerns have been reported in several studies. Dewalt et al. (1996) demonstrated that aquacultural development has been accompanied by concern about destruction of mangrove forest, depletion of fishing stocks, disappearance of seasonal lagoons and deteriorating water quality. Flaherty et al. (1999) studied the development of

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

449

500000

Area, ha

400000 300000 200000 100000 0 1980

1990

2000

2010

Year Agricultural lands

Sundarbans

Wetlands

Settlement & others

Fig. 4. Change in land use in the study area. Fig. 6. Temporal change of precipitation in the study area during 1980e2008.

inland shrimp farming in Thailand and discussed the environmental concern. They concluded that irrigated agriculture needs to be proactive in prohibiting conversion of agricultural lands into shrimp farming before it is entrenched in ways that are difficult to reverse either ecologically or politically. Ali (2006) studied the impact of shrimp farming on rice ecosystem in a village in Southern Bangladesh and found that the study area experienced transformation of 79% of its prime quality rice fields into shrimp farms during the period between 1985 and 2003. The study also found that shrimp farming caused soil degradation that significantly

affected rice yield. The study conducted by Ali (2006) focused only in a single village. But the current study area comprises a huge part of the Ganges delta. The current study is based on land use classification in the Ganges delta and linking it with ecosystem services. The study area covers the Khulna division of Bangladesh within the Ganges delta. It is the southwest region of Bangladesh and includes three districts of Khulna division e Satkhira, Khulna and Bagerhat. The total land area of the study area excluding the Sundarbans is 12,221 square kilometer. The study area covers 3576 villages which

Table 3 Transformation matrix of land use and land cover change (ha) between 1989 and 2008. Transformation matrix

Erosion

Agricultural land

Mangrove

Settlement & others

Wetland

Grand total 1989

Accretion Agricultural land Mangrove Settlement & others Wetland Grand total 2008

e

1981 144,699 562 60,644 14,387 222,273

6970 21 374,253 228 397 381,868

2822 74,348 272 62,475 13,764 153,683

9234 128,446 95 50,313 49,424 237,512

21,008 348,653 386,628 173,945 79,274 1,009,508

1139 11,446 285 1302 14,172

Fig. 5. Transformation of land use and land cover change between 1989 and 2008.

450

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

Fig. 7. Temporal change of maximum temperature in the study area during 1980e2008.

is in contrast to study area of only one village as considered by the study of Ali (2006). Fig. 10 shows a photograph depicting agricultural lands converted into shrimp farms. Many framers in Satkhira-BagerhatKhulna area have switched over to saltwater shrimp (bagda) culture in the recent years from traditional agriculture, allowing more and more saltwater in the land. High profitability of bagda shrimp farming has influenced local people to convert their croplands into shrimp farms which has led to increased shrimp and fish production. However, if one farmer converts the land to saltwater shrimp cultivation, the nearby lands will have little choice than likewise land conversion due to salinization of soil that spreads and reduces crop productivity. 8. Environmental management for sustainable land use The environmental problems associated with shrimp farming have been widely reported as described in earlier section. It has been identified in many studies that saltwater shrimp farming in has many negative environmental impacts including salinization of soil and water, loss of wild and domesticated flora and fauna, mangrove destruction, change in cropping patterns and species composition. Musa (2008) studied land use change and its socioeconomic impacts as a case study of Chakoria Sundarban in Bangladesh. The Chakoria Sundarban is totally different than the Sundarbans. In fact, the Chakoria Sundarban is not even part of the Ganges delta. As such, the current study which focuses on implications of agricultural land use change and its impacts on ecosystem services in the Ganges delta is quite different than the study by Musa (2008). The extensive shrimp farming systems requiring large land areas have contributed most to encroachment of agriculture land and mangrove clearance with increased intrusion of salinity, degradation of land and destabilization of coastal eco-systems (Musa, 2008). Such land use change requires

Fig. 8. Temporal change of rice cultivated area in the study area (Source: BBS, 1979, 1992, 2000, 2010).

significant capital, therefore, only investors and wealthier land owners can get the higher profit from the land conversion while the poor people is left with the environmental consequences that affect their long-term lives and livelihood. The first author of this paper visited Padmapukur union of Satkhira district to assess the socioenvironmental impacts of the switching of shrimp cultivation to agricultural lands. The local people, specially the poor and marginalized ones, identified two important problems i.e., depletion of open water fisheries resources and reduction of agricultural lands that affect their lives, livelihood and environment. Job opportunities for open water fishers and agricultural laborers have been substantially reduced due to depletion of open water fisheries resources and reduction of agricultural lands. As shrimp farming requires saltwater which reduces the soil quality, some farmers need to buy food instead of growing it for themselves. This has made them more vulnerable as far as their livelihood is concerned. If management intervention is not enforced sooner or later, this land use change without a clear and logical planning will further deteriorate the socio-environmental conditions of the study area. An alternative solution is freshwater shrimp cultivation (golda) which can be part of an integrative agriculture system (cropaquaculture). This is advantageous for the farmers as this system increase both income and financial security, provide food for family and does not degrade the environment. In this respect, the Ministry of Land of the Government of Bangladesh can devise land use planning in the Ganges delta inside Bangladesh. The Department of Environment of the Government of Bangladesh should intervene so that further degradation of land by saline water intrusion can be stopped in order to overcome the negative social and environmental impacts.

Table 4 Test of trend for precipitation and maximum temperature in the study area during 1980e2008. Climate variable

Correlation coefficient, r

Trend test statistic

Critical value at 5% significance level (t-distribution)

Existence of trend

Precipitation Maximum temperature

0.229 0.188

1.22 0.99

1.7 1.7

No trend No trend

Fig. 9. Temporal variation of shrimp and fish production (Source: FRSS, 1989, 2001, 2010).

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

451

Fig. 10. Agricultural lands converted into shrimp farms at Satkhira.

9. Conclusions 1. The temporal variation of agricultural land use change and its implications with ecosystem services in the Ganges delta has been explored. With time agricultural lands have been decreased and wetlands have been increased at a very high rate mainly due to the growing popularity of shrimp farming. In a span of 28 years, the agricultural lands have been decreased by approximately 50%, while the wetlands have been increased by over 500%. 2. A large portion (nearly 40%) of the study area is covered by the Sundarbans which remained almost constant which can be attributed to the strict regulatory intervention to preserve the Sundarbans. The settlement & others land use type has been increased to nearly 5%. 3. Reduction of agricultural lands and expansion of wetlands, increase of shrimp and fish production area are attributed to the conversion of agricultural lands into shrimp farming in the study area. The findings suggest that there are significant linkages between agricultural land use change and ecosystem services in the Ganges delta in Bangladesh. 4. The agricultural land use change has social and environmental impacts. Conversion of agricultural lands into shrimp farms affects the lives and livelihood of the poor people. 5. An environmental management plan is proposed for sustainable land use in the Ganges delta in Bangladesh. Acknowledgment The study was carried out within the Assessing Health, Livelihoods, Ecosystem Services and Poverty Alleviation in Populous Deltas (ESPA Deltas) project (http://www.espadelta.net/) with the financial support (NE-J002755-1) of the UK Natural Environment Research Council (NERC), the Economic and Social Research Council (ESRC) and the UK Department for International Development (DFID) under the Ecosystem Services for Poverty Alleviation research program. The authors are grateful to the anonymous reviewers for valuable comments which greatly improved the content of the paper. References Ali, A.M.S., 2006. Rice to shrimp: land use/land cover changes and soil degradation in Southern Bangladesh. Land Use Policy 23, 421e435.

Barbier, E.B., 1993. Sustainable use of wetlands valuing tropical wetland benefits: economic methodologies and applications. Geogr. J. 159 (1), 22e32. BBS (Bangladesh Bureau Statistics), 1979. Statistical Yearbook of Bangladesh, first ed. Bangladesh Bureau of Statistics. BBS (Bangladesh Bureau Statistics), 1992. Yearbook of Agricultural Statistics of Bangladesh, fourth ed. Bangladesh Bureau of Statistics. BBS (Bangladesh Bureau Statistics), 2000. Yearbook of Agricultural Statistics of Bangladesh, twelfth ed. Bangladesh Bureau of Statistics. BBS (Bangladesh Bureau Statistics), 2010. Yearbook of Agricultural Statistics of Bangladesh, twenty-second ed. Bangladesh Bureau of Statistics. Boyd, J., Banzhaf, H., 2006. What are Ecosystem Services? The Need for Standardized Environmental Accounting Units. Resources for the Future. Discussion Paper No. RFF DP, 06e02. Chaudhury, M., 2008. A Situation Analysis of Ecosystem Services and Poverty Linkages in Bangladesh. Research and Evaluation Division. Bangladesh Rural Advancement Committee (BRAC). DoE (Department of Environment), 2003. Bangladesh National Programme of Action for Protection of the Coastal and Marine Environment from Land-based Activities. Department of Environment. Government of Bangladesh. Dewalt, B., Vergnc, P., Hardin, M., 1996. Shrimp aquaculture development and the environment: people, mangroves and fisheries on the Gulf of Fonseca, Honduras. World Dev. 24 (7), 1193e1208. Flaherty, M., Vandergeest, P., Miller, P., 1999. Rice paddy or shrimp pond: tough decisions in rural Thailand. World Dev. 27 (12), 2945e2060. FRSS (Fisheries Resources Survey System), 1989. Fisheries Statistical Yearbook of Bangladesh (1987e1988). Fisheries Resources Survey System. Department of Fisheries, Bangladesh, p. 5. FRSS (Fisheries Resources Survey System), 2001. Fisheries Statistical Yearbook of Bangladesh (1999e2000). Fisheries Resources Survey System. Department of Fisheries, Bangladesh, p. 17. FRSS (Fisheries Resources Survey System), 2010. Fisheries Statistical Yearbook of Bangladesh (2008e2009). Fisheries Resources Survey System. Department of Fisheries, Bangladesh, p. 26. ILWIS, 2012. Integrated Land and Water Information System (http://52north.org/). (accessed 25.12.12.). Islam, G.M.T., Jaman, S.T., 2006. Modelling sediment loads in the lower Ganges, Bangladesh. Water Manag. 159 (2), 87e94. Islam, S.N., Gnauck, A., 2008. Mangrove wetland ecosystems in GangesBrahmaputra delta in Bangladesh. Front. Earth Sci. China 2 (4), 439e448. Jabbar, M.T., Zhi-Hua, H., Tian-Wei, W., Chong-Fa, C., 2006. Vegetation change prediction with geo-information techniques in the three gorges area of China. Pedosphere 16 (4), 457e467. Johnson, R.D., Kasischke, E.S., 1998. Change vector analysis: a technique for the multispectral monitoring of land cover and condition. Int. J. Remote Sens. 19 (3), 411e426. Khan, S.M., Haq, E., Huq, S., 1994. Wetlands of Bangladesh. Bangladesh Centre for Advanced Studies (BCAS). Holiday Printers Limited, Dhaka, pp. 2e57. Lambin, E.F., Ehrlich, D., 1997. Land-cover changes in sub-Saharan Africa (1982e1991): application of a change Index based on remotely sensed surface temperature and vegetation indices at a continental scale. Remote Sens. Environ. 61, 181e200. Liu, J., Liu, M., Tian, H., Zhuang, D., Zhang, Z., Zhang, W., Tang, X., Deng, X., 2005. Spatial and temporal patterns of China's cropland during 1990e2000: an analysis based on Landsat TM Data. Remote Sens. Environ. 98, 442e456. Mikhailov, V.N., Dotsenko, M.A., 2006. Peculiarities of the hydrological regime of the Ganges and Brahmaputra river mouth area. Vodn. Resur. 33 (4), 389e409 [Water Resources (English Translation.). 33(4), pp. 353e373].

452

G.M.T. Islam et al. / Journal of Environmental Management 161 (2015) 443e452

Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: General Synthesis. Island Press and World Resources Institute, Washington DC. Musa, K.B., 2008. Identifying Land Use Changes and its Socio-economic Impacts: a Case Study of Chakoria Sundarban in Bangladesh. Masters thesis. Department of €ping University, Sweden. Computer and Information Science (IDA), Linko SRDI (Soil Resources Development Institute), 2012. Trends in the availability of agriculture land in Bangladesh. In: Workshop on ‘Research to Inform Food and Nutrition Security Policies’. Dhaka, p. 16.

Sultana, M.S., Islam, G.M.T., Islam, Z., 2009. Pre- and Post-urban wetland area in Dhaka city, Bangladesh: a remote sensing and GIS analysis. J. Water Resour. Prot. 1, 414e421. Toufique, K., Turton, C., 2002. Hands Not Land: How Livelihoods are Changing in Rural Bangladesh. Bangladesh Institute of Development Studies, Dhaka. WARPO (Water Resources Planning Organization), 2003. A System Analysis of Shrimp Production (WP 014). Program Development Office for Integrated Coastal Zone Management Plan. Water Resources Planning Organization. Government of Bangladesh.

Implications of agricultural land use change to ecosystem services in the Ganges delta.

Ecosystems provide the basis for human civilization and natural capital for green economy and sustainable development. Ecosystem services may range fr...
3MB Sizes 0 Downloads 5 Views