MONITORING LAND USE WITH REFERENCE TO AQUACULTURE IN CHINNA CHERUKURU VILLAGE OF NELLORE DISTRICT , ANDHRA PRADESH , INDIA – A REMOTE SENSING AND GIS BASED APPROACH

The present study focuses on the dynamics of conversion of agricultural land to aquaculture over a decade from 1995 to 2013 in Chinna Cherukuru Village (Thotapalligudur Mandal) in Nellore District of Andhra Pradesh State, India. Multi temporal satellite data from 1995’s medium resolution to high resolution IRS LISS IV & Cartosat of 2013 time frame was analysed and mapped using RS & GIS techniques to monitor the dynamics of land transformation from agriculture to aquaculture (1995’s) and conversion back to agriculture in 2013. It was observed that, in 1995 aquaculture was practiced to an extent of 62.35 hectares which accounts to 9.48% of the Total Geographic Area (TGA) of the village (658.01 hectares), whereas in 2001 there is a major conversion from agricultural land to aquaculture accounting to an extent of 237.01 hectares or 36.01% of total village area . However, thereafter there was a significant conversion back to agriculture accounting to an extent of 27.23 hectares or 4.13 % of TGA in 2013. The study tries to understand the underlying reasons for conversion back to agriculture which were due to several factors that include outbreak of diseases in aquatic fauna, natural calamities, variation in production cost / selling cost and non-availability of infrastructure facilities like cold storages etc. The present village level study on LUCC database provides an answer key question about socio-economic issues, land use and cropping pattern which form important input for environmental management. * Corresponding author at: LU&CMD, National Remote Sensing Centre, ISRO, DOS, Balanagar, Hyderabad 500037, India Tel.:04023884239 E-mail: manojraj_saxena@nrsc.gov.in (M. R. Saxena)


INTRODUCTION
Aquaculture has been a fast-growing industry because of significant increases in demand for fish and seafood throughout the world.It is growing more rapidly than any other segment of the animal culture industry (Gang et al. 2005).In India, aquaculture has transformed from a traditional to a commercial activity in the last two decades and the area under shrimp culture has increased from 65,100 ha to 1,75, 674 ha between 19901,75, 674 ha between and 20061,75, 674 ha between (MPEDA, 2007)).The industry has grown enormously, leading to purchase of agricultural and fallow lands by entrepreneurs for setting up small and large-scale aqua farms in Indian coastal states.Although intensive aquaculture practices provide foreign exchange from exports, one may strongly question whether it benefits the country and its indigenous population in terms of sustained socio-economic benefits (Meltzoff and Lipuma, 1986;Goodland and Ledec, 1987;Bailey, 1988;Primavera, 1991).The switching from food to cash deletes the social / cultural experience of sustainable resource use.The progressive exploitation of the ecosystem to expand the economy has made it necessary to redevelop the ecosystem in order to maintain the economy (Regier and Baskerville, 1986).The sustainability issues are intertwined with the environmental and social impacts of shrimp farming.The environmental impacts include conversion of mangrove area into shrimp ponds and consequent loss of the direct and indirect benefits from mangrove ecosystems, conversion of agricultural land, Stalinization of the agricultural land, reduction in paddy production in areas where shrimp ponds are located, Stalinization of nearby aquifers, deterioration of quality of groundwater and discharge of effluents by shrimp farms to the nearby estuaries and rivers causing deterioration of quality of water both irrigation and potable in the surrounding locality (Primavera, 1991;Pillay, 1992;Rajalakshmi, 2002).The expansion of shrimp farming is subject to criticism not only because of the above mentioned offsite environmental factors but also for its on-site adversities.Inappropriate and excess use of chemicals, fertilizers and accumulation of excess feed in the pond bottom makes the soil acidic and unsuitable for any further use either for agriculture or other fish culture, at least in the short run.This leads to the problem of irreversibility (Krutilla and Fisher, 1985) of environmental damage created by a particular economic activity.Moreover, intense use of chemical, fertilizers and antibiotics translate into the disease outbreaks in shrimp ponds and hence pose financial risk to the shrimp farmers.Conventional methods used to estimate aquaculture land use such as manual surveying and collection of secondary data from the farmers, field or revenue records are labour intensive, time consuming, non-repetitive, and inaccessible to remote areas, low in accuracy and not synoptic.Such data do not provide with information on the associated land features of aquaculture farms.Hence, there is a need for a method of obtaining real-time data on a continual basis for the assessment The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-8, 2014ISPRS Technical Commission VIII Symposium, 09 -12 December 2014, Hyderabad, India This contribution has been peer-reviewed.doi:10.5194/isprsarchives-XL-8-927-2014 of larger areas so that coastal aquaculture resources can be utilized effectively.Remote sensing techniques have emerged as appropriate tools in providing with spatial information because of their systematic approach in data acquisition through satellites, affordability, high level of precision and the possibility of obtaining time-series data.Satellite images are increasingly being utilized as data sources in conjunction with geographical information system (GIS) for mapping various land resources and monitoring changes over time.The characteristic absorption feature of water bodies and crop lands has been utilized for their detection from multi-spectral measurements made by IRS/Resourcesat-LISS-3 and LISS-4, Landsat-TM/ETM+ and IKONOS.Global Positioning System (GPS) identifies the position on the earth by using the satellites in space and maps the areal extent of different land types in the field.The present study was carried out in Nellore district of Andhra Pradesh to understand the nature of shrimp farming practices and its transformation from agriculture followed, causes behind such transformation from agriculture to aquaculture and again back to agriculture, its impact on the socioeconomic status of local population, the influence of extension support and the constraints if any faced by the farming community.

Study Area
The study area, Chinna Cherukuru village of Nellore district, Andhra Pradesh is situated towards east 7 km from the district headquarter and lies in between 14°25'40.84"Nto 14°25'59"N and 80° 2'27.08"E to 80° 3'15.89"E.The terrain is nearly level to gently sloping plain.Earlier, a major portion of the study area was under paddy cultivation and subsequently aquaculture ponds were developed.

Data Used
The digital satellite images from Landsat -TM of 1995, IRS P6 -LISS IV of 2001 and 2013 and cadastral map of the present study area were used to delineate and monitor changes in the spatial extent and distribution pattern of aquaculture farms.

Software used
In the present study a GIS and Remote Sensing based approach has been taken to monitor the land transformation to aquaculture.Thus, ArcGIS 10.2.1 and Erdas Imagine 2014 has been used as a powerful tool for spatial analysis.Apart from the spatial analysis the statistical analysis has been done using Microsoft Office Excel 2007.

GIS Analysis
In the present study a cadastral based integrated mapping technique has been adopted for land use categorization.The cadastral database has been designed in ArcGIS 10.2.1 geodatabase and has been updated using multi temporal satellite images, without affecting the owner details.The transformation of land of each land owner has been mapped at different temporal levels.Aquaculture farms with their associated features were mapped using ArcMap.The areal extent and spatial distribution for each dataset were estimated using ArcMap attributes.The detailed work flow of the study is given in Figure 2.  1).

Methodology
Table 1.Change area statistics of the study area According to Landsat data of year 1995, aquaculture was confined to 62.35 ha (Figure 3).During the ground truth verification, it was noted that the small scale farmers were mostly affected due to the WSSV disease outbreak.The optimum and sustainable use of natural resources for aquaculture (and agriculture) can lead to economic gains, although if badly planned and managed, it can also lead to short and long term economic loss (Philips, 1995).In Andhra Pradesh, abandoned aquaculture farms have been converted back to agriculture and the reconversion did not have any ill effects on agriculture production (Jayanthi, 2006).The statistical analysis of land use maps shows changes of land use classes since 1995 to 2013, but marked changes were observed in two classes, agriculture and aquaculture, where as rest of the classes were having marginal changes (Figure 6, 7 and 8).

Figure 1 .
Figure 1.Location map of the study area

Figure 2 .
Figure 2. Workflow of the study Over time from 1995 to 2001 aquaculture activities increased.The IRS LISS 4 data of year 2001 indicated that the area under aquaculture farms rapidly increased to 237.0 ha (Figure 4).Farms have been developed in clusters and larger areas of lands were converted for aquaculture between 1995 and 2001.Whereas, from 2001 to 2013, the most significant change was the decrease of aquaculture ponds.During this time 237 ha. of aquaculture ponds were retransformed (27.23 ha.) to agricultural lands.The maximum increase in aquaculture area from 9.47% to 36.01% of total geographical area occurred between 1995 and 2001 (Figure 5), because of the great attention that aquaculture received as more profitable activity than agriculture.After 2001 it decreased up to 4.86% of the total study area.Agriculture reduced by 174.65 ha. between 1995 and 2001 because of the failure of monsoon.One of the main reasons behind back transformation of aquaculture to agriculture was White Spot Syndrome Virus (WSSV) disease.Viral diseases are a challenging problem for the global shrimp culture industry and disease caused by WSSV has resulted in large scale losses and consequent production losses to the shrimp culture industry in Asia.All age groups and sizes of shrimp are affected by WSSV in all kinds (extensive, semi-intensive and intensive) of aquaculture systems (Karunasager et al., 1997).

Figure 3 .
Figure 3. Land use and land cover map of 1995

Figure 8 .
Figure 6.Distribution of land use classes in 1995