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1.
Temporal changes in ephemeral river courses and associated flood plains, which could not be detected by Landsat MSS due to its poor spatial resolution of 80m, have been identified and mapped within 10% accuracy by Landsat TM False colour composite because of its higher spectral and spatial resolution of 30 m. Over a period of 28 years (1958–86) the river courses widened upto 1.8 times through bank erosion due to the recurring flash floods. The flash floods have also caused morphological, soil fertility and landuse changes in the associated flood plains, which could also be monitored by the Landsat TM.  相似文献   

2.
Rivers flowing through the alluvium invariably have very low gradient forcing the river to flow slowly in a meandering and zigzag path. Nature and intensity of meandering is governed by the geological and tectonic conditions of the river basin. Barak River in tectonically active south Assam (Northeast India) exhibits intense meandering and shifting of the river course. Topographic data of two different years and satellite images of 4 different years covering a section of the Barak River have been investigated to verify the nature of changes undergone by the river through times. This study reveals active northward shift of the river and a prominent neck-cut off in the initial part of the study area. Northward shift of the river also occurred in the area west of Silchar. But, in the western part the river has shifted both towards north and south. Oscillatory shifting in the river channel has also been noticed. The river has shown a overall northward shift which is probably due to uplift of the southern part of the Barak River valley.  相似文献   

3.
The flood-affected areas in Siras district, Haryana, was mapped during 1993 using IRS-1A LISS-II data. Two categories of flood-affected areas viz. (i) standing water, and (ii) wet areas were identified. The flood water was standing in an area of 19676.25 ha, while wet areas covered 16773.75 ha., Silting of Ottu reservoir, mismanagement of river banks and bunds and lack of drainage system were identified, as major causes of floods. Three management practices including (i) desilting of Ottu reservoir, (ii) proper management of river banks and bands, and (iii) constructions of drains to flush out flood water have been suggested to contain the fury of floods. This study will be useful to the planners and administrators in the planning of flood-affected areas.  相似文献   

4.
The evaluation of basin characteristics from the morphometric parameters helps in understanding the physical behaviour of the catchments with respect to floods. The advanced technologies, such as Remote sensing and Geographic Information System (GIS), were used for extraction of drainage networks using Cartosat Digital Elevation Model (DEM) for the Upper Krishna basin, to evaluate the morphometric analysis. Basin morphometric parameters were applied to assess the major influencing catchments which cause flooding in the main Krishna River. The morphometric analysis for the ten major potential flood prone river catchments of the basin reveals that, the river catchments such as Krishna, Koyna, Yerla having the greater tendency to peak discharge in a short period of time to the main Krishna River because of high relief ratio (Rh), high ruggedness number and less time of concentration (Tc). The Don catchment having the highest drainage density (Dd), stream frequency, mean bifurcation ratio and infiltration number causes greater runoff influence on the main Krishna River. The Dudhganga and Panchaganga catchments having highest form factor, medium Dd, texture ratio, Rh and time of concentration causes moderate runoff influence towards main Krishna River. The study indicates that systematic analysis of morphometric parameters derived from Cartosat DEM using GIS provide useful information about catchment characteristics with respect to floods management.  相似文献   

5.
The mapability of Landsat images has opened up a new potentiality for study of channel pattern changes which was earlier not so easy due to nonavailability of suitable evidences at different timespans. Middle Ganga plain covering largely the northern part of Bihar and parts of eastern Uttar Pradesh is in a slate of perpetual flux due to large scale channel migration and avulsion resulting in devastating floods. Mosaic of three Landsat images has helped to study the channel changes which have occurred since 1935. The course of the river Ganga has beeh digitised along a basal line and two dimensional coordinates are taken at as many as more than fifty sample points for studying the magnitude and direction of channel changes during 1935–1975 period. The analysis shows that the main multiple channel river Ganga is under the huge hydrostatic thrust to be shifted towards south of its basin annually at a very high rate of 100 Meter per year all along the course except at its upstream near Ghazipur and at Monghyr where the shifting is towards north. The northward bend at Monghyr may be due to the presence of the Precambrian outliers here. For the multi-and single channelld tributaries of Ganga in channel behaviour is mainly in three directions—the lower water channels in the floodplain of Ganga are shifting to the south in conformity with that of their parent stream, the tributaries in Gogra-Gandak doab are shifting towards east but the shifting of the Kosi-Mahananda group of tributaries in the eastern part of the basin is towards west These channel pattern changes thus known at the interregional scale from the Landsat images may further be integrated with the study in hydrogeomorphology and their pertinent environmental impact.  相似文献   

6.
Study of Landsat MSS imagery and aerial photographs along with selected field checks in Sabi river basin area has thrown some light on the plausible reasons of floods in parts of Rajasthan, Haryana and Delhi regions. It is noticed that the course of river Sabi, a tributary to Yamuna river flowing through the sandy tracks is being controlled by the prominent linears, most of them are faults within the Delhi rocks. But, as the river approaches near Haryana, that controlled course is lost and it develops a very wide river bed, full of sands and have abrupt decrease in its gradient to as low as 2° to 3°. This may be attributed to the migration and aggradational alluvial plains developed thereof, on the western side of Yamuna river. All these factors have been discussed in the paper which shall reflect some points as remedial measures of floods of the Sabi River.  相似文献   

7.
Numerous studies have been carried out during last 20-25 years by different agencies to trace the courses of palaeo river Sarasvati. Varying number of courses of river Sarasvati have been suggested by the different workers in the north-western region. Taking advantage of the developments in satellite/ sensor and digital image processing technologies an attempt has been made to rediscover the course of river Sarasvati and solve the controversy regarding its exact course, in the sand covered Thar desert region. Data available from a variety of ground investigations carried out by different agencies working in this area have been analyzed in support of confirmation of palaeo channels, along the courses mapped under the present study. The results indicate that the river Sarasvati had its course through river Ghaggar and did not drain along the Aravalli hills. Also it did not shift its course drastically and continuously from east to west, as suggested by earlier workers. The image anomalies indicate that river Sarasvati flowed parallel to the river Indus as an independent river system (closer to the north-western Indian border) and did not flow through present course of river Nara. The findings raise the doubt that ‘Rise along Delhi-Hardwar ridge’ as suggested by earlier workers was the main cause for west-ward shift of Sarasvati river and ultimate drainage desiccation in the northwestern region. The analysis indicates towards rise in Himalayas/ Siwaliks and consequent displacements in the Siwaliks and its foot hills region (in the form of Yamuna and Satlej tear faults) as the main cause for drainage desiccation and disappearance of river Sarasvati.  相似文献   

8.
In the Bali and Pali tehsils of Pali district of western Rajasthan, which were affected by floods during the period August 6–10, 1990, using IRS-1A LISS-1 data of post-flood and ground truth, seven flood damage categories viz. (1) loss of bund and slight sheet erosion (2) loss of bunds, severe sheet and rill erosion and few gullies (3) deep gullies (4) water inundated area (5) moderate scouring and sand casting (6) severe scouring and sand casting and (7) river widening and bank cutting have been mapped. Out of seven, four categories could be mapped visually on the raw FCC (post-flood) and remaining three categories could be separated out from the digitally generated FCC. The PC2 was found to contain maximum information on soil erosion/deposition and inundated areas. Density-slicing of band-ratioed output gave maximum information on newly formed channels, water bodies and flow direction. The damage caused to be human beings, animals, agricultural lands, engineering structure by different type of flood hazards under various geomorphic flood zone and comparison between pre-flood and post-flood product has been highlighted.  相似文献   

9.
To evaluate the hydrogeomorphological conditions of Niva river basin Chittoor district, Andhra Pradesh, geological, hydrogeological and geomorphological studies were carried out. through visual interpretation of Landsat 5, FCC with adequate ground truth. The study shows that the Niva river basin is occupied by granites and gneisses of Archaean age with intrusive bodies of dolerites. The recent alluvium deposits are present along the stream courses. The study area is traversed by various directional fractures/lineaments and most of them are NESW, ENE-WSW and EW directions. Groundwater potential of geomorphological units viz. Denudational hill, Residual hill, Pediment, Pediplain and Valley fill is discussed.  相似文献   

10.
Ganga is one of the largest rivers of the world which supports millions of population on its banks. It is a tectonically controlled Himalayan river which also creates havoc due to perennial floods every year. Like most large river systems, it also shifts its course in the Gangetic plains in space and time. The present study measures the variable shift in a selected flood-prone stretch of the Allahabad city lying on the western bank of the Ganga river, taking into account the historical, annual to monthly data (including pre- and post-monsoon shifts) to show the ongoing changes in the river course with possible causes and futher implications. It also discusses for the first time the down stream effect of the Tehri dam on the Ganga river course after it became functional.  相似文献   

11.
A confirmatory study of soil physiographic units identified through aerial photo interpretation technique, in Yamuna alluvial plain, Haryana is presented here. The area under study is part of Yamuna alluvial plain in Sonepat district, Haryana. Shanwal and Malik (1980) studied and mapped this area (semi-detailed) on 1:25,000 scale through areial photo interpretation technique. The soil profile samples of major soil physiographic units of the area were fractionated into sand, silt and clay. Detail mineralagical studies were carried out through electron microscopic and X-ray diffractometer studies in order to know their nature and origin of the parent material. X-ray diffraction data shows that mineralogy of different fractions (Sand, silt and clay) of soils samples, of different physiographic units were similar except Lavee. In this area mica is the dominant day mineral in the soils followed by Kaolinite, chlorite, vermiculite and smectite in decreasing order of their abundances. The occurance of fibrous minerals in coarse clay and silt fraction of soil samples of Lavee physiographic unit is the interesting feature of this area. The presence of fibrous minerals indicates that this overlain material designated as natural Levee in this area is not the alluvium brought down by the river Yamuna but is aeolian material flown from adjoining deseret of Rajasthan and deposited as stabilized sand dune. The fibrous minerals have been reported earlier in the desert of Rajasthan.  相似文献   

12.
An area of about 7500 km2 covering Cauvery delta has been studied from airphotos (1:60,000), Landsats (1:250,000) and survey of India topographic sheets (1:50,000) with a view to delineate various landforms, soils, land use, hydromorphic units, drainage, and flood intensity of the delta. The delta is composed of mainly ancient channels, delta p ains, fossil islands, levees, beach ridges, mangroves marshes and coastal dunes. The various soil types are clayey soils, silty soils, silty loams, sandy loams, coastal sands and alkaline clays. Paddy and sugarcane are dominant crops. The old channels are found to be zones of high ground water potential. The growth of delta seems to be from south to north with twelve abandoned meander lobes and three delta fronts with gradual influx of material into Bay of Bengal. The old rivet courses lying parallel to the present active Coleroon river in third stage of the growth of the delta seem to be severely affected by floods. Moderate to low growth is noticeable in the second stage of the of the delta. The oldest river course which debouched into Bay of Bengal near Adirama-patnam is less affected by floods. The delta plains, fossil islands, disturbed ridges and beach ridges are unaffected. Basing on landforms, soils, land use, hydrogeomorphology and flood intensity the land capability of the delta has been evaluated. About seven classes of land are interpreted.  相似文献   

13.
Kondakarla lake is the largest natural fresh water lake in Visakhapatnam district. The lake is thought to have been formed in stages. There might have been in the past a ‘U’ shaped rim of hills enclosing a basin with a minor drainage system. With the reduction of hills in relative relief, the drainage got obliterated because of excessive deposition of alluvium leaving a gently sloping piedmont and a central shallow depression. An old course of the Sarada river entered the lake and there are evidences in field indicating the old course having got in and got out of the lake, in the absence of a few geomorphic units along the foot-slopes of the hills. These geomorphic units appear to have been removed by the swerving meander loops of the old course. Again, there are a series of four sandy islands in the lake, the configuration and disposition of which indicate deposition in the inside of the meander loops as point bar deposits, while the old course migrated towards southeast of the basin. The lake is thought to have been farmed in the gently sloping basin partially deepened perhaps by migrating course of tha Sarada river. Aggradation at the northestern part besides cutting off of the meander loop, has created a barrier of low relief resulting in a narrow long basin of internal drainage. Neither the structural trend of the hills nor any other features indicate synclinal or anticlinal troughs, ruling out any structural origin for this lake.  相似文献   

14.
Man has had to live with floods since the very inception of his existence. Fury of flood causes heavy damages to both life and property. Accurate flood inundation data is one of the essential requirements for effective management of flood problem. Remote Sensing methods are well suited for acquiring flood inundation data because of synoptic, repetitive coverage of the satellite data. This paper briefs on an attempt to map flood inundated areas in a part of Mahanadi river basin using remote sensing data.  相似文献   

15.
The coastal regions of northern Bay of Bengal (BoB) are one of the most turbid areas owing to the large freshwater discharge from the three major river systems. This study is conducted to investigate the seasonal and interannual variability of total suspended matter (TSM) in the northern BoB. TSM concentration derived from medium resolution imaging spectrometer for the period 2002–2011 is used for this study. TSM concentration is observed to be the highest during summer monsoon season along the north-eastern region, off the Ganges–Brahmaputra river mouth. The variability of the TSM concentration depicts the role of river runoff associated with the summer monsoon in influencing the same. It is observed that the sediment concentration tapers away towards the offshore regions with the maximum extent observed up to 21.5°N latitude. Interannual variability is also observed with highest TSM concentrations occurring in the years 2003, 2008 and 2011 and least during 2004. Time series analysis performed at three major river discharge regions illustrated the distinct and highly variable nature of TSM dynamics prevailing in the northern BoB.  相似文献   

16.
Employing integrated remote sensing and GIS technology the western most part of Tripura region (Northeast India) and adjoining Bangladesh region has been investigated in the light of its geomorphological characteristics. Nature of fold ridges, several streams and the respective drainage basins are well depicted in satellite images and digital elevation model providing meaningful information. Quantitative parameters such as stream sinuosity, drainage basin asymmetry, basin elongation ratio have been computed. Main rivers of the study area, namely the Gomti and Khowai follows extremely meandering path and crosses through the transversely faulted anticlinal ridges. Fluvial anomalies viz. shift in stream channel and the abandoned meandering loops have been inferred and mapped. The Haora river in the study area exhibits northward shift in some part. Development of drainage system towards north and south from the drainage divide along the latitude 23°45′N indicated up arching of the region which is also corroborated by the extracted topographic profiles. It has been observed that several tributary streams have gone dry and agricultural fields are developed along the dried up stream. These derived parameters remained useful to understand the nature of topographical modification attributed to the possible tectonic activity.  相似文献   

17.
Detailed geological, geomorphological, hydrogeological and land use/land cover studies have been carried out for the Kamthi and adjoining areas of district Nagpur by visual interpretation method of remote sensing data of IRS LISS III, FCC of bands 2, 3 and 4. The interpreted data is supplemented as well as cross-checked by field visits to add minor details of lithounits, nature of lithological contacts, geological and geomorphological features. On the basis of these studies, the various lithounits: Archaean metasediments, the Talchir Shale. the Barakar Sandstone, the Kamthi Sandstone, basalt and alluvium have been mapped. Geomorphological units are mainly of denudational and fluvial origins and are represented by dissected plateaus, pediplains, pediments and alluvium. The land use/land cover study shows that a major part of the area is covered by agricultural land followed by built up and waste land. The flowing and stagnant water bodies, mine and mine dump have also been identified. In the present paper, an attempt has been made to delineate the area with reference to ground water prospects into excellent, very good to good, moderate and poor ground water prospect zones. It has been observed that the sandstone lithounits form excellent aquifers while the basalt and shale form moderate to poor aquifers respectively.  相似文献   

18.
Both surface and subsurface evidences exist along the longitudinal section of the Ganga river in Kanpur-Unnao region of Central Ganga Plain indicating the effect of tectonic subsidence. While the surface evidences are discontinuous chain of high uplands with escarpments on the southern bank of the Ganga river and the wide flood plain on the northern side, the subsurface evidences are in terms of sudden deepending of the granitic basement towards north followed by deposition of coarse sand and gravel forming thick aquifers in the close vicinity of present channel of the Ganga river. The petrological examination of the aquifer material also indicates that the material has been derived from a deformation zone.  相似文献   

19.
During the past decades, large amounts of diffuse contaminated soil material have been deposited in the floodplains of the river Rhine in the Netherlands. The dynamic character of this river causes a large spatial variability in the contamination level of its floodplain soils. Characterisation of the spatial variability exclusively based on soil sampling and analysis is often insufficient and expensive. Hyperspectral images can provide additional spatial information for a proper characterisation of the contamination situation of river floodplains. This paper describes the possible application of soil spectroscopy to estimate metal concentration levels in river floodplains. Soil reflectance spectra in the visible-near infrared region (VNIR) were measured in the laboratory for soil samples taken from two river floodplains along the river Waal, the main tributary of the river Rhine in the Netherlands. A multivariate calibration procedure using partial least squares (PLS) regression was applied to establish a relationship between reflectance spectra in the visible-near infrared (VNIR) region and spectrally active soil characteristics (organic matter and clay content) that are intercorrelated with concentration levels of Cd and Zn. Results of the analysis of two river floodplains are summarised and the influence of scale-level and sub soil material on the prediction capability is discussed.  相似文献   

20.
A hydrogeomorphic approach is used in analyzing hydrologic conditions in the Mehsana and Banaskantha districts of Gujarat state. Using Landsat images, it was possible to delineate geological units, hydrogeomorphic features and vegetation density levels on a regional scale. A relationship between hydrogeomorphic features and vegetation density levels along with ground based hydrologic data was established in Mehsana district and the same was extended to the adjoining Banaskantha district. The ground water potential areas identified were from alluvium and piedmont zone. On the basis of different vegetation density levels, these areas were further subdivided into three different potential zones as regards the availability of groundwater viz. good, fair and poor. The applicability of the remotely sensed data has been found quite useful in quick identification of regional hydrogeomorphic setting of the area.  相似文献   

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