An analysis of snow cover changes in the Himalayan region using modis snow products and in-situ temperature data

Maskey S., Uhlenbrook S., Ojha S.

Ministry of Energy, Nepal

ojhasunal@hotmail.com

Amidst growing concerns over the melting of the Himalayas’ snow and glaciers, we strive to answer some of the questions related to snow cover changes in the Himalayan region covering Nepal and its vicinity using Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products from 2008 to 2008 as well as in-situ temperature data from two high altitude stations and net radiation and wind speed data from one station. The analysis consists of trend analysis based on the Spearman’s rank correlation on monthly, seasonal and annual snow cover changes over five different elevation zones above 3,000m. There are decreasing trends in January and in winter for three of the five elevation zones (all below 6,000m), increasing trends in March for two elevation zones above 5,000 m and increasing trends in autumn for four of the five elevation zones (all above 4,000 m). Some of these observed trends, if continue, may result in changes in the spring and autumn season river flows in the region. Dominantly negative correlations are observed between the monthly snow cover and the in-situ temperature, net radiation and wind speed from the Pyramid station at 5,035 m (near Mount Everest). Similar correlations are also observed between the snow cover and the in-situ temperature from the Langtang station at 3,920 m elevation. These correlations explain some of the observed trends and substantiate the reliability of the MODIS snow cover products.

Gis assessment of land use changes in some traditional Nigerian cities

Oluwafemi O.A.¹, Adeoye O.O.²

1Department of Geographic Information System,Centre for Geodesy and Geodynamics,Toro Bauchi State. National Space Research and Development Agency

walefemi007@yahoo.com

2Deapartment of Geography,Obafemi Awolowo University Ile-Ife, Nigeria

dotwaila@yahoo.com

This study analyzed the spatial and temporal changes in land use between 1978 and 2003 in a part of Southwestern Nigeria using some sets of image data. To make the images comparable, they were georeferenced, resampled and enhanced for visualization in a GIS environment. The tonal values recorded in the images with the features on the ground were validated by ground truthing. The result of ground truthing was combined with visual image interpretation as training sites for supervised classification. Eight different land uses were identified and used to classify the image data. The results indicated changes in the land use with forest loss of 53,469.23 hectares and increase in the areal extent of arable farmlands (9,441.88 to 15,923.20); tree crop plantations (558.76 to 4,774.30); fallow (23,397.9 to 59,436.8); and settlements (943.39 to 2,089.57 hectares). In addition, the coverage area of bare soils and bare rocks also increased from 2,213.28 to 4,149.62 and 7,340.62 to 12,948.23 hectares respectively.