流域面源集成管理系统的设计与应用

利用矢量数据结构的地理信息系统(GIS)软件和模拟模型集成开发流域面源污染管理系统.以上海市苏州河流域为例,通过土地利用类型、土壤类型、子流域等图层的叠加,将流域空间分割为一系列不规则的矢量多边形,并将这些矢量多边形作为非点源模拟的空间单元;利用组件式地理信息系统平台MapX、Surfer等,设计和开发了无缝集成的苏州河面源管理信息系统的结构、功能和数据库组成,并初步建立了可运行的苏州河流域面源管理信息系统.在系统的支持下,可有效地实现流域面源污染负荷估算、面源污染指数评价、单位面源负荷的等值线绘制以及面源污染的总量控制等功能.所开发的系统,既是面源污染专业软件开发的有益尝试,同时也是流域数字化环境管理的有益探索.     

基于DEM与实测河网的流域编码方法

借助于GIS技术对大流域进行划分与编码.修正实测河道上部分栅格单元的高程,以避免大面积“伪洼地”的出现,从修正后的栅格型数字高程模型(DEM)提取出与实测河网比较一致的模拟河网.提取出模拟河网后,再进行河网的编码,以及流域的划分与编码.提出了一种对Pfafstetter规则的改进方法,并且按照改进后的Pfafstetter规则来对河网与流域进行编码.所有编码工作是由本次研究中专门编制的程序来自动完成.将提出的方法应用于黄河流域,将整个黄河流域划分为8 255个子流域并赋予了Pfafstetter编码.     

Calibrating nonparametric cellular automata with a generalized additive model to simulate dynamic urban growth

Understanding factors that drive urban growth is essential to cellular automata (CA) based urban modeling. Multicollinearity among correlated factors may cause negative effects when building CA transition rules, leading to a decrease in simulation accuracy. We use a nonparametric generalized additive model (GAM) to evaluate these relationships through flexible smooth functions to capture the dynamics of urban growth. A GAM-based CA (termed GAM-CA) model was then developed to simulate the rapid urban growth in Shanghai, China from 2000 to 2015. GAM highlights the significance of each candidate factor driving urban growth during the past 15 years. Compared to logistic regression, the GAM-CA transition rules fitted the observed data better and yielded improved overall accuracy and hence more realistic urban growth patterns. The new CA model has great potential for capturing key driving factors to simulate dynamic urban growth, and can predict future scenarios under various spatial constraints and conditions.     

Development of an urban landslide cellular automata model: a case study of North Vancouver, Canada

Many GIS-based landslide models require detailed datasets that are ideally collected from field measurements, which can incur high costs for carrying out surveys. Even when the data is on hand, implementing physics-based slope stability techniques can be difficult. Common research practice uses differential equations to characterize the dynamic flow of a landslide, but it is often laborious without making substantial simplifications. A possible solution is to implement a cellular automata modeling approach, which represents both spatial and temporal components, to simulate the dynamics of the landslide propagation process. In this study, a simplified cellular automata model is developed for the effective prediction of landslide runouts, where the data requirement is a high resolution digital elevation model (DEM). Parameters, such as slope and slope curvature features, are derived from the DEM and coupled with logistic regression. The developed model is implemented on the Patrick and Dawson-Chu Slide in North Vancouver, Canada. The results from this study site were favorable, given almost 90% agreement between simulated landslides and data obtained for real landslides. In addition, sensitivity analysis was performed on the initiation sites to test the model logic and outputs of the landslide flow.     

Geomorphic positioning and depositional dynamics of river systems in Lower Siwalik basin,Kumaun Himalaya

Qualitative and quantitative analysis of river systems in the Lower Siwalik sequence has enabled characterization of channel patterns, river metamorphosis and resulting sandstone body evolution in time and space. Processes related six lithofacies repeat to generate 8–10 m thick multistoried sandstone complexes deposited in perennial channel belts. Based on lateral mapping of the sandstone bodies, the surfaces of genetic significance ranging from 3^rd, 4^th and 5^th order, suggest presence of meandering, braided and anastomosing river patterns that were responsible for the Lower Siwalik sedimentation. Variation in local base-level in response to allogenic factors including climate and tectonics forced river systems to acquire different patterns. Eustasy seems to control large-scale basin level changes. Quantitatively reconstructed morphological parameters and their comparison with modern and ancient analogues, supported by other independent evidences such as stratigraphical position of sandstone bodies in vertically measured columns and mineralogical characteristics of channel sandstones, enabled to decipher the geomorphic positioning of the Lower Siwalik channels in distal parts of megafan and interfluve areas within the foreland basin setting.     

水质模型研究进展与流域管理模型WARMF评述

分析了以地表水、地下水与非点源为代表的水质模型研究发展历程,揭示了水质模型由经验-机理、单要素(或无机、大量、无毒要素)-多要素(或有机、微量、有毒要素)、单介质-多介质、稳态-动态、点源-非点源-两者统一研究、饱水带-包气带-二者统一研究、小规模分散(河流、湖泊、地下水等)-大规模集成(整个流域)、理论研究-实际应用研究的发展特点。认为当前水质模型正处于由水质研究向以水质为中心的流域管理研究转变的关键时期,给出了一个流域管理新模型WARMF的介绍与特点分析。     

Land use change modeling and the effect of compact city paradigms: integration of GIS-based cellular automata and weights-of-evidence techniques

In recent decades, attaining urban sustainability is the primary goal for urban planners and decision makers. Among various aspects of urban sustainability, environmental protection such as agricultural and forest conservations is very important in tropical countries like Malaysia. In this regard, compact urban development due to high density, rural development containment is known as the most sustainable urban forms. This paper attempts to propose an integrated modeling approach to predict the future land use changes by considering city compactness paradigms. First, the cellular automata (CA) were applied for calculating land use conversion. Next, weights-of-evidence (WoE) which is based on Bayes theory was utilized to calibrate CA model and to support the transitional rule assessment. Several urban-related parameters as well as compact city indicators were utilized to estimate the future land use maps. The results showed how compact development parameters and site characteristics can be combined using the WoE model to predict the probability of land use changes. The modeling approach supports the essential logic of probabilistic methods and indicates that spatial autocorrelation of various land use types and accessibility is the main drivers of urban land use changes.     

Evaluation of the SWAT model for water balance study of a mountainous snowfed river basin of Nepal

In this study, a semi-distributed hydrologic model Soil and Water Assessment Tool (SWAT) has been employed for the Karnali River basin, Nepal to test its applicability for hydrological simulation. Further, model was evaluated to carry out the water balance study of the basin and to determine the snowmelt contribution in the river flow. Snowmelt Runoff Model (SRM) was also used to compare the snowmelt runoff simulated from the SWAT model. The statistical results show that performance of the SWAT model in the Karnali River basin is quite good (p-factor = 0.88 and 0.88, for daily calibration and validation, respectively; r-factor = 0.76 and 0.71, for daily calibration and validation, respectively). Baseflow alpha factor (ALPHA_BF) was found most sensitive parameter for the flow simulation. The study revealed that the average annual runoff volume available at the basin outlet is about 47.16 billion cubic metre out of which about 12% of runoff volume is contributed by the snowmelt runoff. About 25% of annual precipitation seems to be lost as evapotranspiration. The results revealed that both the models, SWAT and SRM, can be efficiently applied in the mountainous river basins of Nepal for planning and management of water resources.     

Characterization of natural colloids from a river and spring in a karstic basin

 Colloids are known to transport contaminants over long distances in natural media. Despite this potentially harmful effect, very few studies have been undertaken in subsurface aquifers. This paper presents the first results of a study of natural colloids and particles in a karstic aquifer. The site was chosen for its coverage by clay layers and peat which deliver various and numerous particle types in water. The methodological part describes three methods used for size determination and sample fractionation of surface water and spring water. These methods have been adapted for the treatment of multiple samples due to the rapid discharge variation typical of karstic aquifers. The analysis of many particle size distributions (PSD) shows that they can be described by a Pareto law. The variation of the slope of the PSD at the spring is mainly dependent on discharge. This behavior is interpreted as a washing of the karstic drains during the first phase of high flow events. Fractionation of the samples allowed application of various characterization techniques to particle size classes. X-ray diffraction (XRD) patterns showed that most of the mineral particles originated from Quaternary deposits and limestones. However the use of scanning electron micrsocopy with energy-dispersive spectrometer (SEM-EDS) detailed the composition of individual particles and revealed particles not found by XRD. These techniques also showed the high complexity of the natural particles and the important place of coprecipitation in their formation. Consequences on the fluxes of particulate matter and its potential role as a carrier of contaminants are discussed. Received: 28 October 1996 · Accepted: 7 July 1997     

物理细胞自动机与岩石弹-脆-塑性性质的细观机制研究

基于能量守恒定律和岩石的基本力学性质,进一步发展了由作者提出的一种用于模拟岩石非线性破坏演化的新方法-物理细胞自动机（PCA）模型。该模型通过岩石内部（或细观）基元（或细胞）间简单的随机相互作用的综合结果来反映岩石系统整体的稳定宏观力学现象。利用PCA模型,研究了形成不同岩石本构关系的本质影响因素,揭示了岩石弹-脆-塑性性质的细观机制,为进一步认知岩石等非均质材料的力学性质提供了一种新的理论方法。同时,其研究思路和结论也可为微观和细观力学的数值模拟方法及新型复合材料的设计提供重要的借鉴。     

Spatio-temporal dynamics of heavy metals in sediments of the river estuarine system: Mahanadi basin (India)

Dynamics of heavy metals in the surface sediments of Mahanadi river estuarine system were studied for three different seasons. This study demonstrates that the relative abundance of these metals follows in the order of Fe > Mn > Zn > Pb > Cr > Ni ≥ Co > Cu > Cd. The spatial pattern of heavy metals supported by enrichment ratio data, suggests their anthropogenic sources possibly from various industrial wastes and municipal wastes as well as agricultural runoff. The metal concentrations in estuarine sediments are relatively higher than in the river due to adsorption/accumulation of metals on sediments during saline mixing, while there is a decreasing trend of heavy metal concentrations towards the marine side. The temporal variations for metals, such as Fe, Mn, Zn, Ni and Pb exhibit higher values during monsoon season, which are related to agricultural runoff. Higher elemental concentrations are observed during pre-monsoon season for these above metals (except Ni) at the polluted stations and for metals, such as Cr, Co and Cd at all sites, which demonstrate the intensity of anthropogenic contribution. R-mode factor analysis reveals that “Fe–Mn oxy hydroxide”, “organic matter”, “CaCO₃”, and “textural variables” factors are the major controlling geochemical factors for the enrichment of heavy metals in river estuarine sediment and their seasonal variations, though their intensities were different for different seasons. The relationships among the stations are highlighted by cluster analysis, represented in dendrograms to categorize different contributing sites for the enrichment of heavy metals in the river estuarine system.     

Chemical weathering and gully erosion causing land degradation in a complex river basin of Eastern India: an integrated field,analytical and artificial intelligence approach

Hot and humid subtropical plateau regions are susceptible to land degradation in the form of weathering and gully erosion. Here, we investigate chemical weathering, gully erosion and cohesiveness through field-based measurements with a view to understand the controlling factors of potential land degradation, in complex river basin of the Chotanagpur plateau region in Eastern India. The layers of controlling factors of gully erosion were developed and prioritized considering boosted regression tree (BRT), alternative decision tree (ADT), particle swarm optimization (PSO) and random forest (RF) algorithms in the R software, and the results of these methods were also validated using receiver operating characteristic (ROC) curves. The spectroscopic analysis was carried out of collected soil samples to measure the degree of chemical weathering and cohesiveness. Furthermore, the climatic elements like temperature and rainfall were also considered for estimating the chemical weathering. The results of the gully erosion models (i.e., BRT, ADT, PSO and RF) show remarkable accuracy with ROC values of 0.93, 0.89, 0.91 and 0.84, respectively. An advanced decision tree model was integrated with the results of degree of chemical weathering and cohesiveness in geographical information system platform. The land degradation map developed from this approach shows that 10.53% of the study area is highly affected, whereas 17.36% area is moderately affected and the rest of the 73.85% area is less affected by land degradation. Our results provide essential information for policy makers in adopting measures for minimizing and controlling the land degradation. Our novel approach is significant to assess land degradation to a large scale.

     

Analysis of extreme precipitation and its variability under climate change in a river basin

Natural Hazards - This study investigated the variation of extreme precipitation on a catchment under climate change. Extreme value analysis using generalized extreme value distribution was used to...     

Major ion chemistry of groundwater in a river basin: a study from India

Groundwater is the prime source in the area of Varaha River Basin, Andhra Pradesh, India. Groundwater samples collected during pre- and post-monsoon were analyzed for major ion chemistry to understand the operating mechanism of geochemical processes for variation of groundwater quality. Low ionic concentration is observed in the groundwater occurring at topographic-highs and towards the river compared to the rest of the area. This is caused by the influence of recharge water. Geochemistry of groundwater is observed to be mainly controlled by the rock-weathering, mineral dissolution, leaching, ion exchange and evaporation, and is subsequently modified by the anthropogenic and marine activities. Contribution of residual soluble salts below the depth of 5 m from the ground surface is high, while it is low beyond the depth of 5 m. Anthropogenic activities cause an accumulation of excess residual soluble salts in the former depth and the content of this soluble matter is reduced by the clay products beyond the latter depth. Seasonal ionic concentration of groundwater is greatly influenced by the recharge process with reference to topographical features, lithological characteristics and anthropogenic activities. Groundwater quality is classified as mixed and non-carbonate alkali groups due to a combined action of geogenic/anthropogenic and marine sources, respectively. The groundwater quality is above the adequacy level for both drinking and irrigation, and appropriate management measures are recommended for sustainable development.     

A distributed water-heat coupled model for mountainous watershed of an inland river basin of Northwest China (I) model structure and equations

It is absolutely necessary to quantify the hydrological processes in earth surface by numerical models in the cold regions where although most Chinese large rivers acquire their headstreams, due to global warming, its glacier, permafrost and snow cover have degraded seriously in the recent 50 years. Especially in an arid inland river basin, where the main water resources come from mountainous watershed, it becomes an urgent case. However, frozen ground’s impact to water cycle is little considered in the distributed hydrological models for a watershed. Took Heihe mountainous watershed with an area of 10,009 km², as an example, the authors designed a distributed heat-water coupled (DWHC) model by referring to SHAW and COUP. The DWHC model includes meteorological variable interception model, vegetation interception model, snow and glacier melting model, soil water-heat coupled model, evapotransporation model, runoff generation model, infiltration model and flow concentration model. With 1 km DTM grids in daily scale, the DWHC model describes the basic hydrological processes in the research watershed, with 3∼5 soil layers for each of the 18 soil types, 9 vegetation types and 11 landuse types, according to the field measurements, remote sensing data and some previous research results. The model can compute the continuous equation of heat and water flow in the soil and can estimate them continuously, by numerical methods or by some empirical formula, which depends on freezing soil status. However, the model still has some conceptual parameters, and need to be improved in the future. This paper describes only the model structure and basic equations, whereas in the next papers, the model calibration results using the data measured at meteorological stations, together with Mesoscale Model version 5 (MM5) outputs, will be further introduced.     

Runoff and sediment yield modeling using SWAT model: case of Wadi Hatab basin,central Tunisia

This study presents an application of the model Soil and Water Assessment Tool (SWAT) to simulate daily and monthly water flow and sediment fluxes in the Wadi Hatab watershed (2200 km²) located in central Tunisia. The study basin is characterized by a significant climatic contrast, abrupt topography, and soil fragility, resulting thereby in flash floods and important water erosion rates. This alarming situation requires urgent interventions in order to preserve water and soil resources, implying the need for a decision tool for proper integrated management of the watershed. The model was calibrated and validated based on a comparison of simulated and observed flow rates at the basin outlet (hydrometric station Khanguet Zazia), during the periods 1987–1988 and 1989–1990, respectively. The comparison was based not only on visual inspection of the agreement between observed and simulated time series, but also on statistical parameters. Indeed, for the daily time step application, the Nash—Sutcliffe efficiency (NSE) values were 0.52 and 0.61, and the coefficient of determination (R²) was 0.54 and 0.61 for calibration and validation, respectively. As for the monthly time-step application, the obtained NSE values were 0.67 and 0.89 while R² values were 0.83 and 0.87 for calibration and validation, respectively. This clearly shows the reasonably good agreement between simulated and observed flow rates. In terms of erosion, the model gave sediment yield values ??of 1.15 and 5.37 t/ha/year during the periods of calibration and validation, respectively.     

Interplay between river discharge and topography of the basin floor in a hyperpycnal lacustrine delta

Basin‐floor topography influences the flow path of hyperpycnal plumes and delta morphology during progradation of the Red River delta in Lake Texoma, USA. The Red River discharge is typically a hyperpycnal plume due to elevated total dissolved solids. Because the river plume is a bottom‐hugging hyperpycnal flow, lake bathymetry and topography strongly influence deposition and subsequent delta morphology. In addition to elevated total dissolved solid concentrations compared with Lake Texoma water, the density contrast of the Red River outflow is increased by high suspended‐sediment concentrations during high‐discharge events. Steep lateral slopes in the Lake Texoma basin deflect hyperpycnal river plumes and, subsequently, change the delta progradation direction before the delta reaches the opposite bank of the lake. Analysis of multi‐temporal aerial and satellite images indicates that the hyperpycnal delta follows the steepest lake‐bottom gradients, corresponding to the pre‐impoundment river thalweg (i.e. bypassing shallow parts of the lake). An analytical model for the hyperpycnal‐plume trajectory indicates plume deflection during low‐discharge or high‐discharge events, towards the deepest part of the basin. The magnitude of plume deflection is a function of river discharge and basin‐margin gradients. Plume deflection can vary between 10° and 80° from the channel axis towards the old river thalweg. The high deflection appears in the case of maximum basin side gradients of 12·8° and in conditions of low river discharge. During low‐discharge periods, the Red River delta builds a lobate shape with multiple terminal distributary channels whereas, during high‐discharge periods the Red River delta builds an elongate shape with a single large distributary channel. The elongate morphology of the delta is formed through the development of a single distributary channel and abandonment of the other distributaries. Therefore, the lobate shaped delta is expected to be preserved in the rock record.     

Using GIS-based distributed soil loss modeling and morphometric analysis to prioritize watershed for soil conservation in Bago river basin of Lower Myanmar

Bago River is an important river in Myanmar. Although shorter than other rivers, it has its own river system, and people along the river rely heavily on it for their daily lives. The upper part of the watershed has changed rapidly from closed forest to open forest land in the 1990s. Since the recent degradation of the forest environment, annual flooding has become worse during the rainy season in Bago City. This paper aims at determining soil conservation prioritization of watershed based on soil loss due to erosion and morphometric analysis in the Bago Watershed by integrating remote sensing and geographic information system (GIS) techniques. In this study, soil erosion of the Bago watershed was determined using the Universal Soil Loss Equation. Such factormaps as rainfall, soil erodibility, slope length gradient, and crop management were compiled as input parameters for the modeling; and the soil loss from 26 sub-watersheds were estimated. Then, the soil erosion maps of the Bago watershed for 2005 were developed. The resulting Soil Loss Tolerance Map could be utilized in developing watershed management planning, forestry management planning, etc.     

Land cover change dynamics mapping and predictions using EO data and a GIS-cellular automata model: the case of Al-Baha region,Kingdom of Saudi Arabia

The present study designed to monitor and predict land cover change (LCC) in addition to characterizing LCC and its dynamics over Al-Baha region, Kingdom of Saudi Arabia, by utilizing remote sensing and GIS-cellular automata model (Markov-CA). Moreover, to determine the effect of rainwater storage reservoirs as a driver to the expansion of irrigated cropland. Eight Landsat 5/7 TM/ETM images from 1975 to 2010 were analyzed and ultimately utilized in categorizing LC. The LC maps classified into four main classes: bare soil, sparsely vegetated, forest and shrub land, and irrigated cropland. The quantification of LCC for the analyzed categories showed that bare soil and sparsely vegetated was the largest classes throughout the study period, followed by forest, shrubland, and irrigated cropland. The processes of LCC in the study area were not constant, and varied from one class to another. There were two stages in bare soil change, an increase stage (1975–1995) and decline stage (1995–2010), and the construction of 25 rainwater-harvesting dams in the region was the turning point in bare soil change. The greatest increase was observed in irrigated cropland after 1995 in the expense of the other three categories as an effect of extensive rainwater harvesting practices. Losses were evident in forest and shrubland and sparsely vegetated land during the first stage (1975–1995) with 5.4 and 25.6 % of total area in 1995, while in 1975, they covered more than 13.8 and 32.7 % of total area. During the second stage (1995–2010), forest and shrubland witnessed a significant increase from 1569.17 km² in 1975 to 1840.87 km² in 2010. Irrigated cropland underwent the greatest growth (from 422.766 km² in 1975 to 1819.931 km² in 2010) during the entire study period, and this agriculture expansion reached its zenith in the 2000s. Markov-CA simulation in 2050 predicts a continuing upward trend in irrigated cropland and forest and shrubland areas, as well as a downward trend in bare soil and sparsely vegetated areas; the spatial distribution prediction indicates that irrigated cropland will expand around reservoirs and the mountain areas. The validation result showed that the model successfully identified the state of land cover in 2010 with 97 % agreement between the actual and projected cover. The output of this study would be useful for decision makers and LC/land use planners in Saudi Arabia and similar arid regions.