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Water Quality of the River Yamuna in the Delhi Stretch: Key Determinants and Management Issues 总被引：1，自引：0，他引：1
The assessment of water quality of the River Yamuna in the Delhi stretch was carried out by determining changes in the concentration levels of 19 physico‐chemical parameters. It was observed that vegetation plays an important role in acting as a biological sink for mineral nutrients, thereby restoring the water quality. It is proposed that restoration of the inundation pattern of floodplains would greatly help in re‐aeration of the overlying water and re‐absorption of pollutants through mud/water exchanges. 相似文献
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An investigation was made in five wetland areas in the valley of the river Jhelum north-west of Srinagar. Only two of the regions have regular inlets and outlets, the others are only rain-fed. The water temperature is closely connected with the air temperature, and in the shallow water it determines also the oxygen concentration. The chemical characteristics of the alkaline and hard waters show pronounced annual variations, which are determined by the autotrophic bioactivity especially for nutrients and carbon dioxide. Due to the increased pH-values also biogenic decalcification with correspondingly reduced calcium(II)-ion concentrations results in the water. In each of the wetlands seven to ten stations were investigated, which had been chosen according to the dominance conditions of vegetation. For the differentiations as to time and space of the water chemism the variance analysis shows significant differences, except for water temperature and alkalinity. 相似文献
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Chaman Gul Shi-chang Kang Badar Ghauri Mateeul Haq Sher Muhammad Shaukat Ali 《山地科学学报》2017,14(10):2013-2027
Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects(Passu: 36.473°N, 74.766°E;Momhil: 36.394°N, 75.085°E; Trivor: 36.249°N,74.968°E; and Kunyang: 36.083°N, 75.288°E) in the upper Indus basin, northern Pakistan, from 1990-2014. The snow-covered areas of the selected glaciers were identified and classified using supervised and rule-based image analysis techniques in three different seasons. Accuracy assessment of the classified images indicated that the supervised classification technique performed slightly better than the rule-based technique. Snow-covered areas on the selected glaciers were generally reduced during the study period but at different rates. Glaciers reached maximum areal snow coverage in winter and premonsoon seasons and minimum areal snow coverage in monsoon seasons, with the lowest snow-covered area occurring in August and September. The snowcovered area on Passu glacier decreased by 24.50%,3.15% and 11.25% in the pre-monsoon, monsoon and post-monsoon seasons, respectively. Similarly, the other three glaciers showed notable decreases in snow-covered area during the pre-and post-monsoon seasons; however, no clear changes were observed during monsoon seasons. During pre-monsoon seasons, the eastward-facing glacier lost comparatively more snow-covered area than the westward-facing glacier. The average seasonal glacier surface temperature calculated from the Landsat thermal band showed negative correlations of-0.67,-0.89,-0.75 and-0.77 with the average seasonal snowcovered areas of the Passu, Momhil, Trivor and Kunyang glaciers, respectively, during pre-monsoon seasons. Similarly, the air temperature collected from a nearby meteorological station showed an increasing trend, indicating that the snow-covered area reduction in the region was largely due to climate warming. 相似文献
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