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Land Use/Land Cover Changes Through Satellite Remote Sensing Approach: A Case Study of Indus Delta, Pakistan.

Introduction

Land use/Land cover (LULC) change deals with identification of various natural and human activities, qualitative assessments and the socio-economic context. LULC changes are used in human activities and natural hazards on land. Satellite Remote Sensing (SRS) is broadly used to investigate and monitor Land use/Land cover at different scales (Seto and Kaufman, 2003). Nowadays, remote sensing with Geographical Information Systems (GIS) and Global Positioning System (GPS) have provided more comprehensive monitoring of LULC changes than remote sensing alone. SRS is a technique for investigation, quantification and mapping of LULC patterns and their changes without field work. It is a useful technique to monitor LULC and environmental changes as results of human activities (Rehman et al., 2016). It is very well suited for reflection of wave currents, tides, shallow water, mangroves, wetland, soil degradation, vegetation, cultivated land and coastal changes.

The Indus Delta extends from Korangri Creek to Sir Creek (Fig.1). The Indus Delta consists of seventeen major and several minor creeks. The Indus Delta and its coastal zones are the most important coastal environment for mangroves and related habitats. It is important for fisheries, mineral resources and aqua-culture. Once upon a time, the Indus Delta was close to Hyderabad and now it is in Thatta. Chandio et al. (2011) recognizedthe reasons of degradation of Indus Delta. This degradation is observed for last two decades due to decrease of freshwater from Kotri downstream. The saline water of Arabian Sea has been growing and water creeping under sub surface is dangerous for fauna, flora, crops and fish breading.

The objectives of the present study are as follows:

* To identify the land use/land cover patterns of the Indus Delta in 2000 and 2014 with Satellite Remote Sensing.

* To evaluate the land use/land cover changes of Indus Delta between 2000 and 2014.

* To investigate the LULC classes with ground surveying.

Materials and Methods

The study used satellite remote sensing and GIS Landsat-7 ETM+ (March 8, 2000) and Landsat-8 OLI/TIRS (April 8, 2014) satellite images were downloaded from official Earth Explorer USGS distribution website (http://earthexplorer.usgs.gov) and Google Earth imageries were also used in the study.

Supervised classification is characterised as the way of utilizing samples of known identity to classify pixels of obscure character (Cambell, 2002). Samples of known personality are pixels situated inside preparing regions (Rehman et al., 2016; Sohail, 2012; Cambell, 2002). Supervised classification of the acquired images was carried out with the ERDAS Imagine 2013 software. Land use/Land cover classes were classified using supervised classification (Fig. 2).

Field work is a very important part of the research, for assessment of ground realities with classified maps through various parameters including questionnaires, interviews, photographs and location identified with a GPS device. All parameters of field survey are applied in the study.

Results and Discussion

The area of dense mangrove in the dark green colour is shown in Fig. 3 and Table-1 on the map. It is 56.82 [km.sup.2] in the supervised classification of 2000 and it declined to 43.82 [km.sup.2] in the supervised classification of 2014. The difference is 12.99 [km.sup.2] decreases and the rate of declined area of dense mangrove is 0.93 [km.sup.2] per year during 2000-2014. The normal mangrove shown in the light green colour is 584.46 [km.sup.2] in the year of 2000 and it increased to 909.39 [km.sup.2] in 2014.
Fig. 2. Mangrove status according to many respondents in field survey.
Reasons behind increased ordecrease of mangrove

Mangrove increase due to plantation of Mangrove         76%
Mangrove decreased due to unavailability of freshwater  20%
Mangrove are no change                                   4%

Note: Table made from pie chart.


The difference is 324.93 [km.sup.2] increases and the rate is 23.21 [km.sup.2] per year.

The Indus Delta covers an area of about 41,440 [km.sup.2] and is the 7th largest mangrove forest in the world. Eight mangrove species were reported before in the Indus Delta, but nowadays only three mangrove species (Avicennia marina, Rhizophora mucronata and Aegiceras corniculata) are found, of which Avicennia marina covers up to 95-98% of the mangrove forests (Rehman et al., 2015). On the basis of field survey, questionnaire and interviews, Fig. 2 shows that about 76% respondents out of 300 respondents, who participated in the survey, said that mangrove forest increased due to several plantations of mangroves, 20% respondents said mangroves decreased due to unavailability of fresh water and 4% of respondents said no change. Figure 4 shows the nursery of species of mangrove forest observed in field survey namely, Avicennia marina, Aegiceras corniculata, Ceriops tagal and Rhizophora mucronata.

Mangrove forest is very important for our environment, ecology and biodiversity. Mangrove forest functions as barrier of floods, storms and cyclones, and as habitats for fish, shrimp and migrating birds. Sindh Forest Department and other organizations like WWF, IUCN, and Indus Forever have planted mangroves in the creeks of Shah Bandar, Bin Qasim, Sajawal, and Keti Bandar. In 2009, Pakistan made World Record of Guinness Book for planting 545,000 mangroves in a single day.

Figure 3 and Table-1 show that the area of cultivated land is 1780.01 [km.sup.2] in 2000 and it increased to 2529.45 [km.sup.2] in 2014. The difference is 749.44 [km.sup.2] increase and the rate is 53.53 [km.sup.2] per year during 2000-2014. Other vegetation took 336.54 [km.sup.2] in 2000 and it reduced to 55.96 [km.sup.2] in 2014. The difference is 280.58 [km.sup.2] decrease and the rate is 20.04 [km.sup.2] per year during 2000-2014.

Major crops in the Indus Delta region are cotton, rice, wheat, sugarcane, maize, mango, banana, dates, guava, water melon, musk melon, pumpkin, capsicum, chilies, brinjal, onion and tomatoes. On the basis of field survey and questionnaires, out of the 300 respondents who participated in the survey, 20% respondents have below 20 acres cultivated land, 12% respondents have 20 to 40 acres cultivated land, 8% respondents have above 40 acres cultivated land, 60% respondents have no cultivated land (Fig. 5). 80% aforementioned crops are grown at Indus River, lakes and canals area. The region has been experiencing many agricultural problems like sea water intrusion, water logging and salinity, unavailability of freshwater, and less rainfall, which bring significant impact to agricultural land use (Fig. 6).
Fig. 5. Area of agriculture land.

Agricultural area of respondents (%)

Below 20 acres        20%
20-40 acres           12%
Above 40 acres         8%
No agricultural land  60%

Note: Table made from pie chart.


Figure 3 and Table-1 show that the area of wet mudflat is 2439.85 [km.sup.2] in 2000 and it is declined to 2149.31 [km.sup.2] in 2014. The difference is 290.54 [km.sup.2] and the rate of reduction is 20.75 [km.sup.2] per year during 2000-2014. Some area of wet mudflat is converted and adds to some area of normal mangrove and dry mudflat area. As far as dry mudflat is concerned, the total area of dry mudflat is 185.79 [km.sup.2] from classification of 2000 that is increased to 356.80 [km.sup.2] from the classification of 2014. The extent of increase is 171.01 [km.sup.2] and the rate of increased area of dry mudflat is 12.21 [km.sup.2] / year during 2000-2014.
Fig. 6. Problems faced on agricultural land on the basis of field
survey.

Problem face on agricultural land

Sea water intrusion            22%
Water logging & salinity        6%
Un-availability of freshwater  24%
All of these                   48%

Note: Table made from pie chart.


Figure 3 and Table-1 also show that the area of wet barren/vacant land cover is about 1735.72 [km.sup.2] from the classification of 2000 declined to 891.14 [km.sup.2] in the year of 2014. The change of reduced area of wet barren/ vacant land is 844.59 [km.sup.2] and the rate of reduced area is 60.33 [km.sup.2]/year during 2000-2014. Due to some area of wet barren/vacant land is converted to some area of dry barren/vacant land. As far as dry barren/vacant land is concerned, the area of dry barren/vacant land is 152.96 [km.sup.2] in 2000 that is increased to 528.27 [km.sup.2] in 2014. The change of increase in area is 375.31 [km.sup.2] and the rate of increase area is 26.81 [km.sup.2]/year during 2000-2014.

Figure 3 and Table-1 show that the area of turbid water is 2454.98 [km.sup.2] in 2000 that is increased to 2513.98 [km.sup.2] in the year of 2014. The change area during study period is increased to 59 [km.sup.2] and rate of increase is 4.21 [km.sup.2]/year during 2000-2014. As far as deep water is concerned, the area of deep water is 2220.82 [km.sup.2] that is decreased to 1983.66 [km.sup.2] in 2014. The change of reduced area is 237.16 [km.sup.2] and rate of reduction of deep water is 16.94 [km.sup.2]/year during 2000-2014.

Figure 7 indicates a strong and positive relationship between Satellite Remote Sensing techniques and ground realities of land use/land cover classes of Mirpur Sakro and Ghorabari area of Indus Delta. Black points show GPS location on field survey. Photos at the top of he figure show the area's environmental problems. First two photos capture to Armani Farm near Pitiari creek. A few years ago, this farm was very healthy, but now it has become dried due to sea level rise and unavailability of fresh water. The photos on the left and bottom of he figure mention agricultural practice in different areas. However, the photos on the right side of Fig. 8 indicate some socio-economic activities and lakes of that area.

Factors affecting LULC changes of Indus Delta. Several factors affect the land-use/land cover changes of the Indus delta.

* Freshwater plays a vital role for survival of mangrove ecosystem, biodiversity and ecology of the Indus Delta. After the construction of Kotri Barrage, the flow of fresh water below Kotri downstream is insufficient. For survival of natural habitat i.e., mangroves, fish, bird, mammals, agricultural land, and freshwater of 27 MAF is required (IUCN, 1991). But now, only 0.72 MAF freshwater released. Due to this shortage all major and minor creeks of Indus Delta fill in sea water except Khober creek. In the last three decades agricultural land around creeks of the Indus Delta was badly destroyed like the Armani Farm in Pitiari creek, shown in Fig. 8 (a-b). Furthermore, red rice was cultivated in this region but now it is absent here.

* Because of rising sea water level, the salinity of that area is also increased. Sea level rise is about 15 to 20 cm at the rate of 1.5 to 2 mm per year (IPCC, 2007). On the basis of satellite measurements, sea level rise is3.1 mm/year. Around 525,000 ha of agricultural land of six sub-districts of Thatta were affected; due to this several people were migrated (Memon and Thappa, 2010). Salinity has up surged from 3.8% to 4.2% on the other hand salinity of Arabian Sea is 3.6%. It is observed in field survey that sea water entered in land as mentioned in Fig. 8 (c-d).

* Cyclones and heavy monsoon rainfall are also affected. In super flood of 2010 around 20 million individuals were affected, 1,781 deaths resulted, and the flood crushed more than 1.89 million homes. Cyclone A2 in 1999 was one of most powerful cyclones in Pakistan history. The cyclone eye developed in the Keti Bander area. This cyclone was most destructive and 6400 people died in the coastal belt of Sindh.

Conclusion

Satellite remote sensing is very helpful to analyse and monitor land cover changes. It provides vast range of bands for the detection of special patches in the area. Temporal datasets give good comparison of the historical and present condition in the study area. Landuse/Land cover of Indus Delta are continuously changing with respect to the time period. Normal mangrove, cultivated land, dry mudflat, dry barren/vacant land and turbid water increased with 324.93 [km.sup.2] (23.21 [km.sup.2]/year), 749.44 [km.sup.2] (53.53[km.sup.2]/year), 171.01 [km.sup.2] (12.21 [km.sup.2]/year), 375.31 [km.sup.2] (26.81 [km.sup.2]/year), and 59 [km.sup.2] (4.21 [km.sup.2]/year), respectively during the period of 2000-2014. Mangroves were planted in various creeks area by Sindh Forest and Wildlife Department, SCCP, IUCN, WWF etc. in the year of 2009 to2013. Cultivated land increased after the flood of 2010 and 2013 in northern part of Indus Delta. While dense mangrove, other vegetation, wet mudflat, wet barren/vacant land and deep water decreased by 12.99 [km.sup.2] (0.93 [km.sup.2]/year), 280.58 [km.sup.2] (20.04 [km.sup.2]/year), 290.54 [km.sup.2] (20.75 [km.sup.2]/year), 844.59 [km.sup.2] (60.33 [km.sup.2]/year) and 237.16 [km.sup.2] (16.94 [km.sup.2]/year), respectively during 2000-2014. Some areas of other vegetation land are converted and added to some other area of cultivated land during 2000 to 2014. Similarly some other areas of wet mudflat and wet barren/vacant land are converted and add to some area of normal mangrove in southern part of Indus Delta. Sea water intrusion and lack of fresh water have negatively affected the ecology, biodiversity and land use degradation.

References

Campbell, B. J. 2002. Introduction to Remote Sensing. 3rd edition, London: Taylor and Francis, UK.

Chandio, N. H., Anwar, M. M., Chandio, A. A. 2011. Degradation of Indus delta, removal mangroves forestland its causes: A case study of Indus River delta. Sindh University Research Journal-SURJ (ScienceSeries), 43: 67-72.

IPCC, 2007. Impacts, Adaptation and Vulnerability Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M.L Parry, O.F Comziani, J.P Palutikof, vander Linden. and C.E Hanson (eds.) IPCC. 1000 pp., Cambridge University Press, Cambridge, United Kingdom,.

IUCN, 1991. Effects of the Indus water accord on the Indus delta ecosystem. Korangi, Ecosystem Project, 22pp., IUCN (International Union for Conservation of Nature) Pakistan.

Memon, J.A., Thapa, G.B. 2010. Impacts of upstream irrigation development on deltaic landscape, resources and livelihood-A case of Indus Delta in Sindh Province, Pakistan. International Journal of Environmental and Rural Development, 1: 67-72.

Rehman, Z., Khanum, F., Kazmi, S.J.H. 2016. Evaluation of land cover changes at the coast of Sindh through successive landsat imageries. Journal of Earth Science & Climatic Change, 7: 325.

Rehman, Z., Kazmi, S.J.H., Khanum, F., Samoon, Z.A. 2015. Analysis of land surface temperature and NDVI using geo-spatial technique: A case study of Keti Bunder, Sindh, Pakistan. Journal of Basic and Applied Sciences, 11: 514-527.

Seto, K.C., Kaufmann, R.K. 2003. Modelling the drivers of urban land use change in the Pearl River Delta, China: integrating remote sensing with socioeconomic data. Land Economics, 79: 106-121.

Sohail, A. 2012. Mapping land cover/land use and coastline change in the eastern Mekong delta (Viet Nam) from 1989 to 2002 using remote sensing. M.Sc. Thesis in Geoinformatics, TRITA-GIT EX 12-007, 76 pp., School of Architecture and the Built Environment, Royal Institute of Technology (KTH), Stockholm, Sweden. ISSN 1653-5227.

Zia ur Rehman (a*) and Syed Jamil Hasan Kazmi (b)

(a) Power Development Sindh Energy Department, Government of Sindh, Karachi, Pakistan

(b) Department of Geography, University of Karachi-75270, Pakistan

(*) Author for correspondence; E-mail: ziarockies86@gmail.com

(received March 23, 2018; revised July 16, 2018; accepted August 23, 2018)
Table 1. Calculated area ([km.sup.2]), Change ([km.sup.2]) and Rate
([km.sup.2]/year) from supervised classification of 2000 and 2014.

LULC Class Name         2000 Area     2014 Area     Change 2000-2014
                        ([km.sup.2])  ([km.sup.2])  Area ([km.sup.2])

Dense mangrove             56.82         43.82       -12.99
Normal mangrove           584.46        909.39       324.93
Cultivated land          1780.01       2529.45       749.44
Other vegetation          336.54         55.96      -280.58
Wet mudflat              2439.85       2149.31      -290.54
Dry mudflat               185.79        356.80       171.01
Wet barren/vacant land   1735.72        891.14      -844.59
Dry barren/vacant land    152.96        528.27       375.31
Turbid water             2454.98       2513.98        59.00
Deep water               2220.82       1983.66      -237.16
Total                   11947.95      11961.77        13.82

LULC Class Name         Rate2000-2014
                        ([km.sup.2] / year)

Dense mangrove           -0.93
Normal mangrove          23.21
Cultivated land          53.53
Other vegetation        -20.04
Wet mudflat             -20.75
Dry mudflat              12.21
Wet barren/vacant land  -60.33
Dry barren/vacant land   26.81
Turbid water              4.21
Deep water              -16.94
Total                     0.99
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Title Annotation:Special Paper
Author:Rehman, Zia ur; Kazmi, Syed Jamil Hasan
Publication:Pakistan Journal of Scientific and Industrial Research Series A: Physical Sciences
Article Type:Case study
Date:Sep 1, 2018
Words:2860
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