Joint U.S.-Egypt workshop for Space Technology & Geo-information for Sustainable Development, NARSS-Cairo 2010

RICE CROP MONITORING IN EGYPTIAN NILE DELTA USING EGYPTSAT-1 DATA

S.Arafat, A.Afify, M.Aboelghar and A.Belal,

National Authority for Remote Sensing and Space Sciences

ABSTRACT

The objective of this study is to monitor the main economical crops in Egypt and to apply remote sensing data as specified by EgyptSat-1. The integrated dataset can be used for predicting the crop productivity to serve the soil and water management. The mosaic of EgyptSat-1 was projected on the region of Nile delta. This mosaic was characterized by the band combination of green, red and near infrared. Rice area was assessed through the supervised classification based on the spectral signature of NDVI as well as to be controlled by visual assessmant that based on the local reference level of the experienced interpreters. The masked image out of roads, canals and fish ponds was classified for the annual, perennial crops and urban. Then, the annual crops were sub- divided into rice and others. The result indicated that the total rice area was 1550769 feddan (651323 Hectare). This area coverage indicated that the cropped land with rice was managed for over cultivation more than the assigned and documented area by the proper plan for rice cultivation. This over cultivated area was assessed as 488771 feddan (205284 Hectare) (46% from the total rice area). The research approach and initial results are described in details.

Key words: EgyptSat-1, remote sensing data, rice crop monitoring

INTRODUCTION

Rice is one of the world’s major staple foods and rice accounts for approximately 15% of the world’s arable land [1]. A unique physical feature of paddy fields is that the rice is grown on flooded soils. This feature is significant in terms of both trace gas emissions and water resources management. Seasonally flooded rice paddies are a significant source of methane emissions [2], contributing over 10% of the total methane flux to the atmosphere [3], which may have substantial impacts on atmospheric chemistry and climate. Agricultural water use (in the form of irrigation withdrawals) accounted for ~70% of global fresh water withdrawals [4]. Egypt is the largest rice producer in the Near East region. The Egyptian rice yield is one of the highest in the world (9.1 tonnes per hectare in 2001). Rice cultivation takes place in Egyptian Nile delta especially in the northern part. Due to the intrusion of sea-water, most of agricultural lands in the northern Nile delta are affected by different degrees of salinity. In these areas, rice production helps to leach the salt from upper soil layers and thus reclaim the land for agricultural activities. Because of limited water resources, the government of Egypt has tried to limit rice cultivation but cultivation has continued to expand due to rice production's high profits, and Egypt is today a major rice exporter. In Egypt, the national policy of water management, the scarcity of water irrigation, the high soil salinity in North delta and the high profit of rice cultivation are considered the main factors that form the rice map of the country. Therefore, there is an urgent call for an automated, regular and accurate system to monitor rice fields. The dynamic and multi-temporality of satellite remote sensing could be the most sufficient method to support the decision makers with an accurate and timely efficient figure of the amount and the distribution of rice cultivation across the country. Optical satellite remote sensing provides a practical mean to meet the requirement of improved regional-scale datasets of rice fields. A number of studies have explored the potential of images from Landsat and NOAA Advanced Very High Resolution Radiometer (AVHRR) to identify rice fields ([5]; [6];[7] ;[8]; [9]). Those studies that identified rice paddies using fine-resolution Landsat Thematic Mapper (TM) data primarily used image classification procedures. Those studies that used moderate-resolution AVHRR images were primarily based on the temporal development of the Normalized Difference Vegetation Index (NDVI) and local knowledge (e.g., crop calendars) of rice fields. In the current study, a complete coverage of the Egyptian satellite EgyptSat-1 data was used to monitor all rice fields in ten governorates of Egypt and complete statistical data were provided. This work will be combined in future with survey of rice cultivation belt to show the areas with highest priorities as rice producers.

MATERIALS AND METHODS

Thirty four EgyptSat-1 images that cover all rice farms in the period from June 16 to July 27, 2009 were used for classification process and rice mapping (Figure 1).

Figure (1): Coverage of EgyptSat-1 data

Geometric correction was carried out using ground control points to give the image the integrity of a map, correct for distortions and to enable the manipulation of the images with other geographic database. The image was geo- referenced using the nearest neighbor resembling algorithm with RMS error less than 0.5 pixel using digital topographic maps of the study area with scale of 1:50,000. One hundred rice ground checkpoints collected through field observation were used as training samples to run Maximum likelihood classifier. The result was checked against fifty rice ground check points distributed in the whole study areas.

RESULTS AND DISCUSSION

A complete statistics of all rice producing governorates in Egypt were produced and maps showing the spatial distribution of rice cultivations in each governorate are shown in table (1) and figure (2) respectively.

Table (1): Areas of rice cultivations in (hectare) for all governorates

Potential rice Actual rice % of Governorate area area Increasing Increasing Alexandria 1344 2716 1372 102 Behira 73449 134021 60572 82 Kafr Elsheikh 115500 150208 34708 30 Dakahlia 126000 159180 33180 26 Gharbia 29400 49436 20036 68 Sharkia 74088 113400 39312 53 Damietta 23940 26948 3008 13 Ismaeliia 1478 2604 1126 76 Port Said 840 6258 5418 645 Qaliobiya 0 6552 6552 Total 446039 651323 205284 46

Figure (2): Rice maps of eight rice producing governorates

As an urgent request from the Ministry of Agriculture, the current research work was carried out to identify the total area and the distribution of rice cultivations in all rice producing governorates in Egypt. The basic idea that the rice area should be adaptive with the amount of available water irrigation for each governorate. Soil characteristics are also key points in this subject. Saline soil requires large amount of water irrigation for salt leaching to be suitable for agricultural activities. In this case, cultivating rice could be the best solution. At the same time, other areas with non-saline soil could be cultivated with other crop types. According to the land cover classification assessed by field observations and as shown in table (1) and figure (2). It was found that all rice producing governorates in Egypt overcame the potential rice cultivation area that was decided by the government. The percentage of increment of actual rice areas over the potential ones ranged from 13% in Damietta governorate to 645% in Port Said governorate. The classification process and field observation showed over 6000 hectare of rice in Qaliobiya governorate which is not allowed to cultivate rice.

CONCLUSION AND RECOMMENDATIONS

This work was carried out upon a request from the Ministry of Agriculture to estimate total rice areas and the distribution of rice cultivations. Basically, the potential area of rice cultivation was decided by the Ministry of Agriculture according to the availability of water irrigation and the soil characteristics of each governorate. The high profit from rice cultivation comparing to other summer crops encourages the farmers to overcome the rules. This situation calls for more strict legislations and more effective crop management policies. This work could be carried out yearly for all crop types including rice to support crop management policies and national agricultural decision.

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