GIS技术在流域设计径流计算中的应用

以新疆某抽水蓄能电站为例,探索GIS技术在设计径流计算中的应用。首先基于数字高程模型（DEM）和ArcGIS平台提取流域特征信息;然后应用ArcGIS平台,对降水量等值线图和径流等值线图进行矢量化处理（包括图形扫描、图形配准和矢量化等）;最后在ArcGIS平台同时打开流域水系图层、降水量等值线图层和径流深等值线图层。量算两相邻等值线间的流域面积,并采用面积加权法推求流域的降水量和径流深。计算结果表明,GIS技术解决了在等值线图上描绘出设计断面以上流域的问题;解决了因等值线分布不均匀时,如何量算两相邻等值线间的流域面积的问题。     

Estimation of Soil Erosion for a Himalayan Watershed Using GIS Technique

The fragile ecosystem of the Himalayas has been an increasing cause of concern to environmentalists and water resources planners. The steep slopes in the Himalayas along with depletedforest cover, as well as high seismicity have been major factors in soil erosion and sedimentation in river reaches. Prediction ofsoil erosion is a necessity if adequate provision is to be madein the design of conservation structures to offset the ill effects of sedimentation during their lifetime.In the present study, two different soil erosion models, i.e. theMorgan model and Universal Soil Loss Equation (USLE) model, have been used to estimate soil erosion from a Himalayan watershed.Parameters required for both models were generated using remotesensing and ancillary data in GIS mode. The soil erosion estimated by Morgan model is in the order of 2200 t km^-2 yr^-1 and is within the limits reported for this region.The soil erosion estimated by USLE gives a higher rate. Therefore, for the present study the Morgan model gives, for area located in hilly terrain, fairly good results.     

区域综合管网地理信息系统(GIS)的建立

为满足决策、管理和施工的需要,采用高新技术和方法来高效管理地下各类专业管线,已成为当务之急．地理信息系统(GIS)所提供的空间数据管理与分析功能,为复杂管网系统的管理提供了很好的解决途径．文中介绍了北方某港口保税区综合管网地理信息系统GIS的建立过程、背景、功能及应用。     

Runoff Analysis for a Small Watershed of Tono Area Japan by Back Propagation Artificial Neural Network with Seasonal Data

The rainfall runoff (R-R) process was studied for two small sub-basins having different sizes in a mountainous catchment of Tono area Japan. The runoff and other meterological data have been collected in this catchment for the last 14 years. The major objective of this study was to construct numerical models for these sub-basins to predict runoff after 1/2 and 1 h. The effects of season and the size of the catchment on R-R process were also investigated. The hydrogeological conditions of the catchment were studied prior to the analyses. The data obtained for summer (rainy) and winter (dry) seasons were treated separately in order to study the seasonal effects on the model development. The back propagation artificial neural network technique (BPANN) and the multivariate autoregressive and moving average models (ARMA) were adopted for the analysis. It was found that for very small catchments the seasonal effects are dominant and therefore separate models should be developed for each season to obtain better forecasting estimates. It was also found that the predictions by BPANN models were better than multivariate ARMA models for intense rains having complex R-R relationships in summer. On the other hand, both the modelling techniques yielded almost similar results for smaller rains in winter. It was also found clearly that the accuracy of prediction decreased with the increase of the time period for prediction.     

Geographic Information Systems (GIS) for the Determination of Inundation Maps of Lake Mogan,Turkey

Abstract

The use of geographic information systems (GIS) allows for a very efficient analysis of spatial hydrologic data for water resources projects especially for water control studies. In this respect, flood hydrographs for Mogan basin, Turkey for different durations and return periods are determined by using Soil Conservation Service (SCS) method. The basic parameter of the SCS method, curve number (CN), is evaluated by using GIS employing digital land use and hydrologic soil group data derived from analog maps. A Digital Elevation Model (DEM) of Mogan basin is constructed by making use of topographic maps with a scale of 1:25,000. Flood hydrographs for these three productive subbasins of Lake Mogan are attached and superimposed to obtain the total flood hydrographs. Total flood hydrographs entering into Lake Mogan are routed by Puls Method to determine the outflow hydrographs from the lake; then, associated lake levels are computed. Furthermore, inundation maps of Lake Mogan are obtained; these results are presented by GIS techniques.     

Integrated Water Resource Development Plan for Sustainable Management of Mayurakshi Watershed, India using Remote Sensing and GIS

Integrated watershed management requires a host of inter-related information to be generated and studied in relation to each other. Remote sensing technique provides valuable and up-to-date spatial information on natural resources and physical terrain parameters. Geographical Information System (GIS) with its capability of integration and analysis of spatial, aspatial, multi-layered information obtained in a wide variety of formats both from remote sensing and other conventional sources has proved to be an effective tool in planning for watershed development. In this study, area and locale specific watershed development plans were generated for Mayurakshi watershed, India using remote sensing and GIS techniques. Adopting Integrated Mission for Sustainable Development (IMSD) guidelines, decision rules were framed. Using the overlay and decision tree concepts water resource development plan was generated. Indian Remote Sensing Satellite (IRS-1C), Linear Imaging Self Scanner (LISS-III) satellite data along with other field and collateral data on lithology, soil, slope, well inventory, fracture have been utilized for generating land use/land cover and hydro geomorphology of the study area, which are an essential prerequisites for water resources planning and development. Spatial data integration and analyses are carried out in GIS environment.     

基于新型接口混成控制的微网并网研究

研究了微网并网的接入方式及控制方法。通过对几种微网并网接口的比较,得出微网经电压源换流器接入配电网的并网方式具有结构紧凑、占地面积小等优点,更符合环保和“绿色电力”的需要。分析了微网并网系统的混成特性,提出利用先进灵活的混成控制方法进行微网并网控制,不仅具有控制算法简单、计算量小、计算速度快、跟踪精度高、动态响应速度快和多目标控制等优点,而且混成控制器易于设计,还具有很强的扩展性。通过Matlab／Simulink／Stateflow仿真平台,验证了该微网并网方式和控制方法的正确性和实用性。     

Estimation of Sediment Yield for a Rain,Snow and Glacier Fed River in the Western Himalayan Region

Assessment of soil erosion, sediment transport and deposition of sediment in the reservoirs, irrigation and hydropower systems are considered essential for the land and water management. The magnitude of sediment transported by rivers has become a serious concern for the water resources planning. In the present study, an assessment of sediment yield has been made for the Satluj River, which flows through the western Himalayan region. Two approaches have been used for the assessment of sediment yield (i) relationship between suspended sediment load and discharge and (ii) empirical relationship. The first approach was used for Satluj Basin up to Suni (52 983 km²), Kasol (53 768 km²) and also for the intermediate basin between Kasol and Suni (785 km²). The sediment-discharge relationship was developed using daily data for a period of three years (1991–1993) for different basins and was applied for each basin for the years 1994 and 1996 for estimation of sediment yield. The second approach, which gives annual sediment yield, has been used for a small intermediate basin only because of data availability constraints. For estimation of the sediment yield using the empirical relationship, various geographical parameters such as land use, topographical etc. were generated using Geographic Information System (GIS) technique. The annual sediment yield for the intermediate basin was estimated for three years and compared with observed values. The trend of difference between computed and observed sediment yield suggested an effect of physical features of mountainous basins. The available empirical relationship was, therefore, revised by incorporating a basin parameter in the equation. This basin parameter represented an integrated effect of slope and spatial distribution of rainfall in the mountainous basin. Using the revised empirical relationship, the sediment yield was estimated for two independent years and a good correlation was found between computed and observed sediment yield.     

Estimation of Urban Impervious Fraction from Satellite Images and Its Impact on Peak Discharge Entering a Storm Sewer System

The runoff coefficient in an urban basin is highly influenced by the impervious and pervious surface fractions since they affect the entity of rainwater entering a storm sewer system. Today these fractions can be estimated by reading high resolution satellite images that are readily available at a relatively low cost. However, this approach involves a certain margin of error when it comes to identifying the various types of cover and hence the total extent of impervious and pervious surfaces. The first problem addressed in this paper thus lies in assessing to what degree the error in the estimation of the two fractions—as derived from a reading of satellite images of the area taken into consideration—may impact the estimation of peak discharge which will be used in turn as a basis for designing or verifying a storm sewer system. A further aspect affecting the entity of rainwater that flows into a storm sewer system is the manner in which the impervious and pervious fractions are connected to the system itself. This type of information may not be deduced from satellite images, but only from an extensive field survey. However, such surveys are feasible only for areas of limited size, whereas they become prohibitive in terms of time and cost in the case of large catchments. An investigation was thus made into whether disregarding the type of connection would significantly affect the peak discharge taken as reference for the design or verification of a storm sewer system. The two above-mentioned problems were addressed in reference to a real case, represented by the town of Codigoro (Ferrara, Italy), in which five small basins with different types of land cover were selected. The results of our analysis show that an estimation of impervious and pervious fractions from high resolution satellite images is sufficiently precise and acceptable for estimating the peak discharge entering the sewer system. By contrast, disregarding the information on how the different areas are connected to the sewer system may lead to a marked overestimation of discharges.     

川中丘陵区一种新型小流域径流输沙模型的建立与应用

径流输沙模型对定量评价水沙的输出响应具有重要的意义。本研究在已有研究成果的基础上，通过对四川盐亭县林山西沟小流域的径流、泥沙进行现场观测与分析，提出含沙量单位线的定义及其确定方法，建立了适应该小流域的径流输沙模型。并应用实测资料进行比较，表明模型的模拟结果可靠，模拟过程确定性系数达0．8以上，为川中丘陵区小流域径流输沙过程的预测预报提供了一个新方法。