Monitoring rangeland ground cover vegetation using multitemporal MODIS data     

Hassan Yeganeh  Seyed jamale Khajedein  Fazel Amiri  Abdul Rashid B. Mohamed Shariff 《Arabian Journal of Geosciences》2014,7(1):287-298

The aim of the present research is to monitor changes in herbage production during the grazing season in the Semirom and Brojen regions, Iran, using multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) data. At first, various preprocessing steps were applied to a topography map. The atmospheric and topographic corrections were applied using subtraction of the dark object method and the Lambert method. Image processing, including false-color composite, principal component analysis, and vegetation indices were employed to produce land use and pasture production maps. Vegetation sampling was carried out over a period of 4 months during June–September 2008, using a stratified random sampling method. Twenty random sampling points were selected, and herbage production was estimated and verified with the double-checking method. Four MODIS data sets were used in this study. The models for image processing and integrating ground data with satellite images were processed, and the resulting images were categorized into seven classes. Finally, the land covers were verified for accuracy. A postclassification analysis was carried out to verify the seven class change detections. The results confirmed that Normalized Difference Vegetation Index (NDVI) and Soil-Adjusted Vegetation Index (SAVI) maps had a close relationship with the field data. The indices produced with shortwave infrared bands had a close relationship with field data where the ground cover and yields were high. The R ² value observed was 0.85. The changes in the pasture vegetation were high during the growing season in more than 90 % of the pastures. During the growing season, most changes in the pastures belonged to class 5 and 2 in the NDVI and SAVI index maps, respectively.  相似文献   

Assessing the impacts of changing land cover and climate on Hokersar wetland in Indian Himalayas     

Shakil Ahmad Romshoo  Irfan Rashid 《Arabian Journal of Geosciences》2014,7(1):143-160

Monitoring the spatiotemporal changes in wetlands and assessing their causal factors is critical for developing robust strategies for the conservation and restoration of these ecologically important ecosystems. In this study, the spatiotemporal changes in the land cover system within a Himalayan wetland and its catchment were assessed and correlated using a time series of satellite, historical, and field data. Significant changes in the spatial extent, water depth, and the land system of the Hokersar wetland were observed from the spatiotemporal analysis of the data from 1969 to 2008. The wetland area has shrunk from 18.75 km² in 1969 to 13 km² in 2008 with drastic reduction in the water depth of the wetland. The marshy lands, habitat of the migratory birds, have shrunk from 16.3 km² in 1969 to 5.62 km² in 2008 and have been colonized by various other land cover types. The land system and water extent changes within the wetland were related to the spatiotemporal changes in the land cover and hydrometeorological variables at the catchment scale. Significant changes in the forest cover (88.33–55.78 km²), settlement (4.63–15.35 km²), and water bodies (1.75–0.51 km²) were observed in the catchment. It is concluded that the urbanization, deforestation, changes in the hydrologic and climatic conditions, and other land system changes observed in the catchment are the main causes responsible for the depleting wetland extent, water depth, and biodiversity by adversely influencing the hydrologic erosion and other land surface processes in the catchment. All these causes and effects are manifest in the form of deterioration of the water quality, water quantity, the biodiversity changes, and the decreasing migratory bird population in the wetland.  相似文献   

Rare Earth Elements Around the Barakah Nuclear Power Plant,UAE     

Al Rashdi  Mouza Rashid  El Tokhi  Mohamed  Alaabed  Sulaiman  El Mowafi  Walid  Arabi  Alya A. 《Natural Resources Research》2020,29(6):4149-4160

Natural Resources Research - Rare earth element (REE) contamination has major consequences for the environment and humans. Some forms of REEs have more serious environmental impacts than others. It...  相似文献   

Spatial and seasonal distribution of intertidal macrobenthos with their biomass and functional feeding guilds in the Naf River estuary,Bangladesh     

Md. Abu NOMAN  MAMUNUR Rashid  M SHAHANUL Islam  M. Belal HOSSAIN 《海洋湖沼学报（英文）》2019,(3):1010-1023

The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals.However,detailed information on macrobenthic communities is rarely available in this area.Our study focused on the seasonal and spatial variability of macrobenthic community structure with their biomass and functional guilds.In total,fortyseven taxa were identified under nine major groups and seven functional feeding guilds.Among macrobenthic taxa,Polychaeta was dominant in both seasons and all over the estuary contributing 60%of total benthos.The mean abundance of macrobenthos was higher during the pre-monsoon(2 972±1 994 inds./m^2)than the monsoon(1 572±361 inds./m^2)being maximum at mid-estuary region and minimum at upper and lower estuary regions.Of the diversity indices,density(P=0.01,P=0.003),the number of taxa(P=0.000 3,P=0.000 9)and Margalef′s Index(P=0.000 4,P=0.001)of macrobenthos were significantly different among stations and seasons.Shannon-Weiner index(P=0.009,P=0.12)and Pielou’s evenness index(P=0.03,P=0.14)had significant differences among stations but not among seasons.Cluster analysis suggested that distribution of macrofauna is strongly influenced by seasonality.Among the feeding types,carnivorous were found to be dominant at the upper and mid-estuarine regions,and herbivorous were at lower estuarine regions.Carnivorous species were dominant in both seasons.Omnivores have shown to be the most abundant feeding type in terms of biomass though herbivores were highest during monsoon.  相似文献   

Bearing capacity performance of soft cohesive soil treated by kenaf limited life geotextile     

Ahmad Safuan A Rashid  Mohammad Gharehzadeh Shirazi  Ramli Nazir  Hisham Mohamad  Fauzan Sahdi 《Marine Georesources & Geotechnology》2020,38(6):755-760

Abstract

This article presents the performance of the short-term bearing capacity on soft clay soil treated by Kenaf geotextile under vertical loading via a small-scale modelling test at unit gravity. The ground model was formulated by consolidating kaolin in a rigid testing compartment. In the loading test, the strip footing was represented by a rigid footing. For the treated case, a series of tests were performed to examine the effects of the burial depth of the Kenaf geotextile on the bearing capacity of the soft soil. The Kenaf geotextile was laid beneath the rigid footing (at the ground surface) and at 50, 75 and 100?mm depth from the soil surface. All the measured results of the Kenaf geotextile treated ground were compared with the untreated ground. The incorporation of Kenaf fibre geotextile was observed to enhance the bearing capacity of soft cohesive clay up to 281% depending upon the depth of the installed geotextile. The geotextile at the surface provided the highest bearing capacity and sustained the highest displacement at failure. The outcome of this research will promote the use of natural fibre geotextiles as sustainable earth reinforcement in temporary earthwork applications.  相似文献   

Spatial and seasonal distribution of intertidal macrobenthos with their biomass and functional feeding guilds in the Naf River estuary,Bangladesh     

Noman  Md. Abu  Mamunur  Rashid  Islam  M. Shahanul  Hossain  M. Belal 《中国海洋湖沼学报》2019,37(3):1010-1023

The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals. However, detailed information on macrobenthic communities is rarely available in this area. Our study focused on the seasonal and spatial variability of macrobenthic community structure with their biomass and functional guilds. In total, fortyseven taxa were identified under nine major groups and seven functional feeding guilds. Among macrobenthic taxa, Polychaeta was dominant in both seasons and all over the estuary contributing 60% of total benthos.The mean abundance of macrobenthos was higher during the pre-monsoon(2 972±1 994 inds./m~2) than the monsoon(1 572±361 inds./m~2) being maximum at mid-estuary region and minimum at upper and lower estuary regions. Of the diversity indices, density(P=0.01, P=0.003), the number of taxa(P=0.000 3,P=0.000 9) and Margalefs Index(P=0.000 4, P=0.001) of macrobenthos were significantly different among stations and seasons. Shannon-Weiner index(P=0.009, P=0.12) and Pielou's evenness index(P=0.03,P=0.14) had significant differences among stations but not among seasons. Cluster analysis suggested that distribution of macrofauna is strongly influenced by seasonality. Among the feeding types, carnivorous were found to be dominant at the upper and mid-estuarine regions, and herbivorous were at lower estuarine regions. Carnivorous species were dominant in both seasons. Omnivores have shown to be the most abundant feeding type in terms of biomass though herbivores were highest during monsoon.  相似文献   

Can farmed salmon production keep growing?     

Yajie Liu  Ussif Rashid Sumaila 《Marine Policy》2008

Time series data was used to compute 5-year moving average rates of growth in salmon aquaculture production over time for four of the world's leading salmon farming countries, and globally. This analysis reveals a decline of 1.2% per year in global farmed salmon production since it peaked in 1966. Analysis of production data for all farmed finfish, both marine and freshwater, shows a decline of 0.34% per year in the growth rate from the peak year. These results have implications for global fisheries policy because it means that it is unlikely that aquaculture alone can meet the fish protein needs of humans.  相似文献   

The migrant anchovy fishery in Kabui Bay,Raja Ampat,Indonesia: Catch,profitability, and income distribution     

Megan Bailey  Christovel Rotinsulu  U. Rashid Sumaila 《Marine Policy》2008

We estimate the unregulated catch and fisher income of the Kabui Bay migrant anchovy fishery operating in the Raja Ampat regency, Papua, Indonesia. Interviews with migrant fishers were conducted in April and November 2006, and estimates were generated through Monte Carlo simulations. Anchovy fisher income averaged US $1835 per year, about twice the average fisher income in the area. The income levels estimated by this study suggests that there is potential for the Raja Ampat Fisheries Bureau to capture some economic rent from the fishery to help fund a fisheries management program, from which Raja Ampat could benefit.  相似文献   

Illegal, unreported and unregulated fisheries catch in Raja Ampat Regency, Eastern Indonesia     

Divya A. Varkey  Cameron H. Ainsworth  Tony J. Pitcher  Yohanis Goram  Rashid Sumaila 《Marine Policy》2010,34(2):228-236

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