首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper examines the effects of watershed complexity in terms of physiography and land use on the specific sediment yield of the Chardavol watershed (1012.946 km2) in Iran. First, specific sediment yield was simulated using spatially distributed hydrological WetSpa model, then the influential factors such as morphometric variables, land-use composition and pattern and soil properties of the watershed were calculated at the sub-watershed scale. Due to the inter-reliant of these watershed characteristics, a partial least squares regression (PLSR) was used to illustrate the relationship between the specific sediment yield and data of 15 selected watershed characteristics. The results showed that the land-use composition and soil properties had the maximum effects on the specific sediment yield and clarified 79% of the variation in the specific sediment yield. Regarding the availability of digital spatial database over the watershed, this simple PLSR procedure could be applied in different watersheds.  相似文献   

2.
‘Watershed Management’ has assumed urgency for planned development of land and water resources and to arrest land degradation process to preserve environment and ecological balance. Decision support to such management planning requires scientific knowledge of resources information, expected runoff and sediment yield, priority classification of watersheds for conservation planning, monitoring of watershed for environmental impact assessment and technologies of GIS for data base creation, scenario development and appropriate decision making. Remote sensing technique is ideally suited to evolve such a management strategy. Scientific basis of this approach is explained.  相似文献   

3.
Abstract

River basin assessment is crucial for water management and to address the watershed issues. So, an integrated river basin management and assessment model using morphometric assessment, remote sensing, GIS and SWAT model was envisaged and applied to Kaddam river basin, Telangana state, India. Morphometric results showed high drainage density ranging from 2.19 to 5.5?km2/km, with elongated fan shape having elongation ratio of 0.60–0.75 with sparse vegetation and high relief. Land use change assessment showed that 265.26?km2 of forest land is converted into irrigated land and has increased sediment yields in watersheds. The calibration (r 2?=?0.74, NSE?=?0.84) and validation (r 2?=?0.72, NSE?=?0.84) of SWAT model showed that simulated and observed results were in agreement and in recommended ranges. The SWAT simulations were used to compute mean annual water and sediment yield from 1997 to 2012, along with morphometric results to categorize critical watersheds and conservation structures were proposed accordingly.  相似文献   

4.
Choice of watershed delineation technique is an important source of uncertainty for cryo-hydrologic studies of the Greenland Ice Sheet (GrIS), with different methods yielding different watersheds for a common pour point. First, this paper explores this uncertainty for the Akuliarusiarsuup Kuua River Northern Tributary, Western Greenland. Next, a standardized, semi-automated modeling framework for generating land-ice watersheds for GrIS land-terminating ice (henceforth referred to as CryoSheds) using geographic information systems (GIS) hydrologic modeling tools is presented. The framework uses ArcGIS and the ArcPy geoprocessing library to delineate two types of land-ice watersheds, namely those defined by: (1) a hydraulic pressure potential with varying water to ice overburden pressure ratios (k-value), which determines theoretical flow paths from the hydrostatic equation, using surface and bedrock digital elevation models (DEMs) and (2) a surface topography DEM alone. Lastly, a demonstration of the CryoSheds method is presented for seven remotely sensed proglacial pour points along the Aussivigssuit River (AR), Western Greenland, and its largest tributaries. GrIS meltwater runoff from these seven nested land-ice watersheds is estimated using Modele Atmospherique Regional (MAR) v.3.2 and runoff uncertainties due to watershed delineation parameter selection is estimated.  相似文献   

5.
Thar desert spreads in western part of Rajasthan, northern part of Gujarat, and some parts of Punjab and Haryana. The terrain is dominated by slightly sloping plains, broken by some dunes and low barren hills. The area is characterized by low average annual rainfall which is erratic in distribution and intensity. Drought will remain a major hindrance for agricultural production in Thar desert. Due to water stress condition, many watershed based development activities has been adopted by government and non-government organizations for the growth and sustainable development of this region. The need of this hour is preparation of a national level watershed atlas of 1:50,000 scale because majority of thematic maps are being produced presently on same or 1:10,000 scale. The manual delineation of watershed boundary in flat terrain based on topographic map will be time consuming and less accurate in the absence of prominent contour lines. Automated approach for watershed delineation using Digital Elevation Model (DEM) along a suitable algorithm has the advantage because the output is not only less time consuming but also independent from human decisions. Hence, a case study has been carried out in Churu sub-basin part of Indus basin which is located in Thar desert region. Depression less DEM with different spatial resolutions was used as input in hydrology tool of ArcGIS spatial analyst function for characterization of watersheds. The Churu sub-basin has been divided into various numbers of watersheds with an average size of 600 km2. These watershed boundaries have been validated with respect to high resolution satellite imageries (IRS P6 LISS IV), Survey of India toposheets, ancillary data and limited field checks.  相似文献   

6.
Hypsometric analysis describes the elevation distribution across an area of land surface. It is an important tool to assess and compare the geomorphic evolution of various landforms irrespective of the factor that may be responsible for it. The major factors governing the evolution of landscape are tectonics and/or climate and the variation in lithology. The present study takes into consideration the watersheds developed over actively deforming Mohand anticlinal ridge in the frontal part of NW Himalaya. The hypsometric analysis has been used as a morphometric parameter, i.e. hypsometric integral, to deduce its relationship with the area of watersheds. Statistical analysis of these parameters has been carried out by classifying them into different classes based on the natural breaks method. This brings out strong relationships for hypsometric integral classes and area classes with the number of watersheds in respective classes and the total area occupied by respective hypsometric and area classes. It has also been found that stronger relationships exist for watersheds on the southern flank as compared to watersheds of the northern flank. It also highlights the presence of an anomalous watershed on the northern flank that is possibly responsible for the weak statistical relationships on the northern flank. Removal of this anomalous watershed always brings out much stronger relationships for the northern flank. The anomalous watershed has been directly attributed to the difference in geologic structure as it is spatially related to the presence of the Bhimgoda Back Thrust (BBT) present in the area. The results are awe inspiring and very promising as they indicate some statistically strong relationships among the hypsometric integral and area of watersheds that are not apparent in the spatial distribution of these parameters, especially in actively deforming areas.  相似文献   

7.
Panchromatic vertical aerial photographs in the scale of 1: 15,000 were interpreted for assessment of erosion in the Bcas River Valley Project catchment, Himachal Pradesh in terms of the erosion intensity units. The erosion intensity units imply the relative quantum of sediment yield as deduced from the probable interaction of the significant parameters of erosion comprising physiography, slope, soil characteristics, Vegetation, land use and the visible erosion conditions. The procedure of photo-interpretation as also computation of sediment yield index for each of the different watersheds in the Beas RVP catchment is discussed. The survey revealed that out ofa total of 494 watersheds involving an area of 5.5 lakh ha, 132 watersheds comprising an area of 1.55 lakh ha, have silt yield index of over 1150 and need soil conservation measures on priority basis. Application of photo-interpretation has proved 2 times more efficient than the conventionai method that was followed in a piain area of Matatilla RVP catchment. In a more simpler terrain than Beas catchment and with ideal photographic scale of 1:60,000, the efficiency is expected to increase by 2-3 times than was achieved in Beas RVP catchment  相似文献   

8.
Soil erosion is a prominent cause of land degradation and desertification in Mediterranean countries. The detrimental effects of soil erosion are exemplified in climate (in particular climate change), topography, human activities, and natural disasters. Forest fires, which are an integral part of Mediterranean ecosystems, are responsible for the destruction of above-and below-ground vegetation that protects against soil erosion. Under this perspective, the estimation of potential soil erosion, especially after fire events, is critical for identifying watersheds that require management to prevent sediment loss, flooding, and increased ecosystem degradation. The objective of this study was to model the potential post-fire soil erosion risk following a large and intensive wildland fire, in order to prioritize protection and management actions at the watershed level in a Mediterranean landscape. Burn severity and preand post-fire land cover/uses were mapped using an ASTER image acquired two years before the fire, air photos acquired shortly after the fire, and a Landsat TM image acquired within one month after-fire. We estimated pre-and post-fire sediment loss using an integrated GIS-based approach, and additionally we analyzed landscape erosion patterns. The overall accuracy of the severity map reached 83%. Severe and heavy potential erosion classes covered approximately 90% of the total area following the fire, compared to 55% before. The fire had a profound effect on the spatial erosion pattern by altering the distribution of the potential erosion classes in 21 out of 24 watersheds, and seven watersheds were identified as being the most vulnerable to post-fire soil erosion. The spatial pattern of the erosion process is important because landscape cover heterogeneity induced especially by fire is a dominant factor controlling runoff generation and erosion rate, and should be considered in post-fire erosion risk assessment.  相似文献   

9.
Geographical design of riparian buffers with long-term vegetation cover for environmental restoration in agricultural watersheds needs to assess how much farmland is located in the buffers of a concerned watershed.Traditionally,this assessment was done by field surveying and manual mapping,which was a time-consuming and costly process for a large region.In this paper,remote sensing(RS) and geographical information system(GIS) as cost-effective techniques were used to develop a catchments-based approach for ...  相似文献   

10.
In order to check the premature siltation of the reservoirs, the Government of India has launched the schemes of soil conservation and integrated watershed management in the catchments of River Valley Projects (RVPs) and Flood Prone Rivers. However, due to lack of sufficient funds and manpower for surveys and soil and water conservation programmes, a priority approach for treatment of the watersheds was developed and followed for implementation of soil conservation and watershed management schemes in India.

This paper deals with the prioritisation of watersheds using GIS approach in a part of Musi river catchment in RR district of Andhra Pradesh. The GIS software package, ARC/INFO version 5.0, was used to digitize, edit, display, analyse and plot the maps. It was concluded that by the creation of computerised data base for the maps, the composite map generation and calculation of area statistics are performed much faster and more accurately compared to the conventional method.  相似文献   

11.
Hydro-ecological modelers often use spatial variation of soil information derived from conventional soil surveys in simulation of hydro-ecological processes over watersheds at mesoscale (10–100 km2). Conventional soil surveys are not designed to provide the same level of spatial detail as terrain and vegetation inputs derived from digital terrain analysis and remote sensing techniques. Soil property layers derived from conventional soil surveys are often incompatible with detailed terrain and remotely sensed data due to their difference in scales. The objective of this research is to examine the effect of scale incompatibility between soil information and the detailed digital terrain data and remotely sensed information by comparing simulations of watershed processes based on the conventional soil map and those simulations based on detailed soil information across different simulation scales. The detailed soil spatial information was derived using a GIS (geographical information system), expert knowledge, and fuzzy logic based predictive mapping approach (Soil Land Inference Model, SoLIM). The Regional Hydro-Ecological Simulation System (RHESSys) is used to simulate two watershed processes: net photosynthesis and stream flow. The difference between simulation based on the conventional soil map and that based on the detailed predictive soil map at a given simulation scale is perceived to be the effect of scale incompatibility between conventional soil data and the rest of the (more detailed) data layers at that scale. Two modeling approaches were taken in this study: the lumped parameter approach and the distributed parameter approach. The results over two small watersheds indicate that the effect does not necessarily always increase or decrease as the simulation scale becomes finer or coarser. For a given watershed there seems to be a fixed scale at which the effect is consistently low for the simulated processes with both the lumped parameter approach and the distributed parameter approach.  相似文献   

12.
To prevent soil loss and achieve better ecological environments, soil conservation measures have been taken during the past decades in the western Loess Plateau of China. In this paper, a case study was taken in Luoyu valley and Lver valley, two sub-watersheds of Xihe watershed and comparison was carried out between them. The main object of this study is to monitor land use/cover changes in the two similar small watersheds utilizing SPOT5 imageries by object-oriented human–computer interactive classification method, further develop the method of spatio-temporal analysis of land use/cover change by using pattern metrics of change trajectories and relative land use suitability index (R) in smaller watersheds, and make comparisons between the two similar small watersheds, taking water and soil conservation measures into consideration. Results show that combining GIS and RS, this method can be perfectly applied to make comparisons between different small watersheds with similar geographical backgrounds. And land use/cover spatiotemporal dynamic change characteristics can be preferably expressed by pattern metrics of change trajectories and R values based on topographical data. Different emphases have been laid according to their own geological backgrounds in the two watersheds and human activities have different effects on the landscapes of the two watersheds. The main change pattern is from slope farmland to terrace (322, the largest in Luoyu valley) or to economic fruit forest (344, the largest in Lver valley). R value of every slope grade in both of the two watersheds drops with the rising of slope degree on the whole and it shows that there is still much to do for people in the two watersheds in consideration that all the R values are still lower than 0.7.  相似文献   

13.
Land use and land cover changes have as consequences several social, economic, and environmental impacts. The understanding of these changes allows a better planning of public policies in order to map and monitor areas more susceptible to environmental problems. This research presents an analysis of the land use and land cover changes of a watershed region located in the Brazilian Amazon, and an evaluation of their impacts on sediment yield. Land use/land cover maps for each of the analyzed time periods (1973, 1984, and 2005) were compiled using images obtained by MSS/Landsat-1, TM/Landsat-5, and the MODIS/Terra sensors. The sediment yield modeling was performed by dividing the watershed into homogeneous subregions. Each of the subregions received average attributes that were used as input parameters for the Universal Soil Loss Equation. The results revealed that up to 2005, around 40% of the study area was already deforested, replaced by agricultural activities. In some parts of the watershed these changes were responsible for an increase of up to 7 ton/ha in annual average sediment yield. This study was successful in providing an assessment of the magnitude and spatial distribution of the changes.  相似文献   

14.
Traditionally, stream and sub‐watershed characterization in GIS has been accom‐ plished using a DEM‐based terrain analysis approach; however, there is a large amount of existing vector hydrographic data difficult to accurately reproduce using DEMs. WaterNet is a GIS/hydrologic application for the integration and analysis of stream and sub‐watershed networks in vector format. Even with vector data, hydrologic inconsistencies between streams and sub‐watersheds do exist, and are revealed in the form of streams crossing drainage divides and sub‐watersheds with more than one outlet. WaterNet rectifies these inconsistencies and couples the two datasets. Most algorithms involving traces of dendritic networks employ a form of tree traversal which requires topologic information to be organized into specialized data structures. On the contrary, WaterNet develops topologic relationships from GIS attribute tables, which, in combination with sorting and querying algorithms, make the calculation process efficient and easy to implement. With the topologic relationships of the streams and sub‐watersheds, WaterNet can perform traces to calculate cumulative network parameters, such as flow lengths and drainage areas. WaterNet was applied to the catchment of the Texas Gulf coast for a total of 100 cataloging units (411,603 km2) and 60,145 stream lines (183,228 km).  相似文献   

15.
Land cover conversion is known to alter the hydrologic regimes of watersheds. While connections between land cover and runoff are generally known, not all land cover alterations result in detectable changes in streamflow, and the quantity of land cover change required to yield a detectable change in streamflow is unknown over a range of watersheds. The connection between land cover change and streamflow was explored for a Hydro-Climatic Data Network (HCDN) watershed. HCDN is a database of USGS gauged streams commonly used to assess the influence of climatic change on streamflow. Watersheds included in the HCDN have been screened to represent "unimpaired" streamflow. Implicit in this definition is the assumption that land cover is relatively unaltered over the streamflow time series. Imagery from the North American Landscape Characterization (NALC) project was analyzed to detect land cover change from 1972 to 1992 in an Oregon watershed selected from the HCDN. A post-classification change detection yielded a 44% rate of landscape change over 20 years. Changes in land cover classes by dominant soil types were paired with the L-THIA model of Purdue University to quantify the effect of land cover change on runoff. Despite land cover changes, simulations confirmed that runoff remained unchanged. This report summarizes recommended steps for applying NALC imagery to detection of landscape change in other watersheds.  相似文献   

16.
Geographical design of riparian buffers with long-term vegetation cover for environmental restoration in agricultural watersheds needs to assess how much farmland is located in the buffers of a concerned watershed. Traditionally, this assessment was done by field surveying and manual mapping, which was a time-consuming and costly process for a large region. In this paper, remote sensing (RS) and geographical information system (GIS) as cost-effective techniques were used to develop a catchments-based approach for identifying critical sites of agricultural riparian buffer restoration. The method was explained through a case study of watershed with 11 catchments and results showed that only four of the catchments were eligible in terms of higher priority for riparian buffer restoration. This research has methodological contributions to the spatial assessment of farming intensities in catchments-based riparian buffers across a watershed and to the geographical designs of variable buffering scenarios within catchments. The former makes the catchments-based management strategy possible, and the latter provides alternative restoration scenarios to meet different management purposes, both of which have direct implementations to the environmental restoration of riparian buffers in the real world. This study, thus, highlights the great potential of RS and GIS applications to the planning and management of riparian buffer restoration in agricultural watersheds.  相似文献   

17.
In the present study, prioritization of sub-watersheds was carried out on the basis of sediment production rate. Further, basic hydrologic information such as peak rate of runoff and annual surface water potential were also assessed for the study watersheds and these are essential requisites for effective watershed management. The 10 sub watersheds of Tarai development project area are selected for the present study. Morphometric parameters pertaining to study area are used in the estimation of sediment production rate. The sediment production rate in the study area varies between 2.45 to 11.0 ha-m/100 km2/year. The remote sensing data has been utilized for generating land use/land cover data which is an essential prerequisite for land and water resource planning and development. The remote sensing data can especially play significant role in collection of real time information from remote areas of river basins for generation of parameters required for hydrologic modeling.  相似文献   

18.
Assessment of the environmental impact of Non Point Source (NPS) pollutants on a global, regional and localized scale is the key component for achieving sustainability of agriculture as well as preserving the environment. The knowledge and information required to address the problem of assessing the impact of NPS pollutants like Nitrogen (N), Phosphorus (P), etc., on the environment crosses several sub-disciplines like remote sensing, Geographical Information System (GIS), hydrology and soil science. The remote sensing data, by virtue of its potential like synopticity, multi-spectral and multi-temporal capability, computer compatibility, besides providing almost real time information, has enhanced the scope of automation of mapping dynamic elements, such as land use/land cover, degradation profile and computing the priority categorisation of sub-watersheds. The present study demonstrates the application of remote sensing, GIS and distributed parameter model Agricultural Non-Point Source Pollution Model (AGNPS) in the assessment of hazardous non-point source pollution in a watershed. The ARC-INFO GIS and remote sensing provided the input data to support modelling, while the AGNPS model predicted runoff, sediment and pollutant (N and P) transport within a watershed. The integrated system is used to evaluate the sediment pollution in about 2700 ha Karso watershed located in Hazaribagh area of Jharkhand State, India. The predicted values of runoff and sediment yield copared reasonably well with the measured values. It is important to emphasize that this study is not intended to characterise, in an exhaustive manner. Instead, the goal is to illustrate the implications and potential advantages of GIS and remote sensing based Hydrology and Water quality (H/WQ) modelling framework.  相似文献   

19.
A distributed parameter model Soil and Water Assessment Tool (SWAT) has been tested on daily and monthly basis for estimating surface runoff and sediment yield from a small watershed “Chhokeranala” in eastern India using satellite data and Geographical Information System (GIS). Several maps like watershed and sub-watershed boundaries, drainage network, landuse/cover and soil texture have been generated. The SWAT model has been verified for the initial phase of monsoon season in the year 2002 using daily rainfall and air temperature. Performance of the model has been also evaluated to simulate the surface runoff and sediment yield on sub-watershed basis for two months (July-August 2002). The results show a good agreement between observed and simulated runoff and sediment yield during the study period. Capability of the model for generating rainfall has been evaluated for 10 years (1992 - 2001) period. The model simulated daily rainfall shows close agreement with the observed rainfall. The present results show that the SWAT model can be used for satisfactory simulation of daily and monthly rainfall, runoff and sediment yield.  相似文献   

20.
Geomorphic and curve number-based run-off estimation approaches are proposed in this study for Olidih watershed, India. Cartosat Digital Elevation Model derived morphometry parameters were used for the computation of run-off. The observed and predicted run-off are uniformly scattered around 1:1 line and coefficient of correlation (R2) is found to be around 0.94 in case of NRCS-CN method. Run-off assessment computed using geomorphological parameters and NRCS-CN approach has improved with the introduction of rainfall correction factor. The improved R2 from 0.3 to 0.86 in this case was attributed to rainfall correction factor computed based on the long-term rainfall average of the study area. Run-off assessment made using composite parameter approach shows R2 values of 0.98 and 0.82 for different initial abstraction losses 0.2 and 0.3, respectively, and has indicated better prediction. Therefore, proposed morphometry-based approaches can be explored as an alternative for simulating the hydrological response of the watersheds.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号