Preliminary comparison of landscape pattern-normalized difference vegetation index (NDVI) relationships to Central Plains stream conditions

We explored relationships of water quality parameters with landscape pattern metrics (LPMs), land use-land cover (LULC) proportions, and the advanced very high resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) or NDVI-derived metrics. Stream sites (271) in Nebraska, Kansas, and Missouri were sampled for water quality parameters, the index of biotic integrity, and a habitat index in either 1994 or 1995. Although a combination of LPMs (interspersion and juxtaposition index, patch density, and percent forest) within Ozark Highlands watersheds explained >60% of the variation in levels of nitrite-nitrate nitrogen and conductivity, in most cases the LPMs were not significantly correlated with the stream data. Several problems using landscape pattern metrics were noted: small watersheds having only one or two patches, collinearity with LULC data, and counterintuitive or inconsistent results that resulted from basic differences in land use-land cover patterns among ecoregions or from other factors determining water quality. The amount of variation explained in water quality parameters using multiple regression models that combined LULC and LPMs was generally lower than that from NDVI or vegetation phenology metrics derived from time-series NDVI data. A comparison of LPMs and NDVI indicated that NDVI had greater promise for monitoring landscapes for stream conditions within the study area.     

Net primary productivity of China's terrestrial ecosystems from a process model driven by remote sensing

The terrestrial carbon cycle is one of the foci in global climate change research. Simulating net primary productivity (NPP) of terrestrial ecosystems is important for carbon cycle research. In this study, China's terrestrial NPP was simulated using the Boreal Ecosystem Productivity Simulator (BEPS), a carbon-water coupled process model based on remote sensing inputs. For these purposes, a national-wide database (including leaf area index, land cover, meteorology, vegetation and soil) at a 1 km resolution and a validation database were established. Using these databases and BEPS, daily maps of NPP for the entire China's landmass in 2001 were produced, and gross primary productivity (GPP) and autotrophic respiration (RA) were estimated. Using the simulated results, we explore temporal-spatial patterns of China's terrestrial NPP and the mechanisms of its responses to various environmental factors. The total NPP and mean NPP of China's landmass were 2.235 GtC and 235.2 gCm(-2)yr(-1), respectively; the total GPP and mean GPP were 4.418 GtC and 465 gCm(-2)yr(-1); and the total RA and mean RA were 2.227 GtC and 234 gCm(-2)yr(-1), respectively. On average, NPP was 50.6% of GPP. In addition, statistical analysis of NPP of different land cover types was conducted, and spatiotemporal patterns of NPP were investigated. The response of NPP to changes in some key factors such as LAI, precipitation, temperature, solar radiation, VPD and AWC are evaluated and discussed.     

THE USE OF FLOOD POTENTIAL INDICES FOR FLOOD PEAK ESTIMATION ON UNGAGED WATERSHEDS1

: The construction of a flood peak index map was attempted for use by hydrologists in the simple format of rainfall maps. Since flood peaks are highly dependent on watershed area, the effect of area was removed. By regression analysis flood peaks of 2.33 and 100-year return periods were found to be proportional to watershed area to the 0.8 and 0.7 powers, respectively. Therefore, indices C_{2 33}= Q_{2 33}/_A0.7 were completed at each gage and plotted on a Pennsylvania map. It was attempted to further remove some of the scatter by regression of C with several other watershed parameters like slope, percent forest cover, and watershed shape, but no significant correlation could be found. The index maps, drawn without attenuation of the scatter, can be used by hydrologists to compute flood peaks as Q = CAⁿ (with n = 0.8 and 0.7 for the 2.33 and 100-year flood peaks, respectively). Flood peak safety factors can be based on visual observation of the index variation in the vicinity of the location for which the flood peak estimate is needed.     

A Conceptual Framework for Selecting and Analyzing Stressor Data to Study Species Richness at Large Spatial Scales

/ In this paper we develop a conceptual framework for selectingstressor data and analyzing their relationship to geographic patterns ofspecies richness at large spatial scales. Aspects of climate and topography,which are not stressors per se, have been most strongly linked withgeographic patterns of species richness at large spatial scales (e.g.,continental to global scales). The adverse impact of stressors (e.g., habitatloss, pollution) on species has been demonstrated primarily on much smallerspatial scales. To date, there has been a lack of conceptual developmenton how to use stressor data to study geographic patterns of speciesrichness at large spatial scales.The framework we developed includes four components: (1) clarification of theterms stress and stressor and categorization of factors affecting speciesrichness into three groups-anthropogenic stressors, natural stressors, andnatural covariates; (2) synthesis of the existing hypotheses for explaininggeographic patterns of species richness to identify the scales over whichstressors and natural covariates influence species richness and to providesupporting evidence for these relationships through review of previousstudies; (3) identification of three criteria for selection of stressor andcovariate data sets: (a) inclusion of data sets from each of the threecategories identified in item 1, (b) inclusion of data sets representingdifferent aspects of each category, and (c) to the extent possible, analysisof data quality; and (4) identification of two approaches for examiningscale-dependent relationships among stressors, covariates, and patterns ofspecies richness-scaling-up and regression-tree analyses.Based on this framework, we propose 10 data sets as a minimum data base forexamining the effects of stressors and covariates on species richness atlarge spatial scales. These data sets include land cover, roads, wetlands(numbers and loss), exotic species, livestock grazing, surface water pH,pesticide application, climate (and weather), topography, and streams.KEY WORDS: Anthropogenic impacts; Biodiversity; Environmental gradients;Geographic information systems; Hierarchy     

AN ECONOMIC AND ENVIRONMENTAL EVALUATION OF ALTERNATIVE LAND DEVELOPMENT AROUND LAKES1

ABSTRACT: The objective of the study was to evaluate alternative land developments around New Hampshire lakes. Alternative development patterns, evaluated by their impacts on the lake area environment and area economy, included residential patterns, commercial patterns, and combinations of these two types. Phosphorus loading of the lake water was used as a proxy variable for changes in the lake water quality. Commercial developments yielded the highest revenues to the town and the local area. It also attracted the most lake users to the area as well as contributing the largest phosphorus loading in the lake waters. Residential developments, although contributing high revenues to the businessmen in the area, yielded less net income to the town. Phosphorus loading levels from residential developments were much lower than lake phosphorus loading by commercial developments.     

PREDICTIVE ASSESSMENT OF SEVERITY OF AGRICULTURAL DROUGHTS BASED ON AGRO-CLIMATIC FACTORS1

ABSTRACT: Past historical evidence indicates that droughts have had great impacts on human life. Drought (or scarcity of water) is assessed based on two key factors, namely, the estimated water demand, and the expected water supply. The formulation of these key factors for a region largely depends on the agro-climatic and economic conditions. Consideration of one such key factor is the relationship between the crop yield and water deficit in the assessment and prediction of agricultural droughts. The varying nature of this relationship from crop to crop adds to the complexity of agricultural drought analysis. To overcome this difficulty in analyzing agricultural droughts of a region, it is adequate to consider and place emphasis on a single crop (i.e., an index crop) grown homogeneously over the major area of the region. From one year to another year, the pattern of water requirement during the growing season of an index crop is rather stationary, and the water supply in arid and semi-arid area is mainly from seasonal random precipitation. In a region, grain yield of the index crop and, in turn, assessment of the severity of drought can reasonably be predicted as a function of the time of crop sowing and the distribution of rainfall, provided that temporal and spatial effects of other contributing factors (crop variety, soil fertility status, crop disease, pest control, cultivation practices etc.) on grain yield are considered to be uniformly distributed (i.e., stable). A predictive method of assessing agricultural droughts in an arid area of western India is presented. The major crop (Pearl Millet) of this region is grown from. July through September. The formulation of the proposed predictive method inherently implies that the grain yield of the main crop is a reliable indicator of agricultural drought. In the development of this predictive relationship (i.e., a regression type model) a number of potential yet simple variables affecting the grain yield in the region were investigated. The soil moisture index, although generally considered significant compared to the simple variables, has been found to account for insignificant variation in the grain yield. Results of our investigations suggest that it would be advisable to exclude the soil moisture index variable from the model. The proposed regression model can be used in the prediction of grain yield of the main crop several months ahead of crop harvesting operations and, in turn, the assessment of agricultural drought severity as mild, moderate, or severe. Such an assessment is expected to be helpful to planners for arranging appropriate measures to effectively combat agricultural drought situations.     

INFLUENCES OF WATERSHED URBANIZATION AND INSTREAM HABITAT ON MACROINVERTEBRATES IN COLD WATER STREAMS1

ABSTRACT: We analyzed data from riffle and snag habitats for 39 small cold water streams with different levels of watershed urbanization in Wisconsin and Minnesota to evaluate the influences of urban land use and instream habitat on macroinvertebrate communities. Multivariate analysis indicated that stream temperature and amount of urban land use in the watersheds were the most influential factors determining macroinvertebrate assemblages. The amount of watershed urbanization was nonlinearly and negatively correlated with percentages of Ephemeroptera‐Plecoptera‐Trichoptera (EPT) abundance, EPT taxa, filterers, and scrapers and positively correlated with Hilsenhoff biotic index. High quality macroinvertebrate index values were possible if effective imperviousness was less than 7 percent of the watershed area. Beyond this level of imperviousness, index values tended to be consistently poor. Land uses in the riparian area were equal or more influential relative to land use elsewhere in the watershed, although riparian area consisted of only a small portion of the entire watershed area. Our study implies that it is extremely important to restrict watershed impervious land use and protect stream riparian areas for reducing human degradation on stream quality in low level urbanizing watersheds. Stream temperature may be one of the major factors through which human activities degrade cold‐water streams, and management efforts that can maintain a natural thermal regime will help preserve stream quality.     

The role of population in understanding Honduran land use patterns

Land use patterns are usually influenced by large variety of factors that act over a broad range of scales. Biophysical, climatic, and socioeconomic factors are important and need to be considered, when distribution of land use is to be understood. The main objective of this study is to test this hypothesis using a statistical analysis at 'supra-local' level. Regression analysis is used to describe land use patterns in Honduras, selected because of its rare combination in Latin America of high population growth and poor biophysical conditions. Furthermore, the aim of the analysis is to specifically highlight two aspects, the effect of spatial and temporal scale and the influence of population density: to determine the influence of spatial and temporal scale, six spatial resolutions at two points in time (1974 and 1993) were included. To determine the role of population density and population growth, this factor was singled out; an analysis of migration patterns was performed; and a measure for technological development was calculated. Multiple regression equations indicate the importance of soil-related, climatic and demographic factors for most of the land uses. Relations appear to be stable in space and time. Rural population density dominates as driver over the whole range of resolutions and for both years, especially for maize where it explains up to 80% of the variation. The strong constant relationship between population and agricultural area could be caused by a lack of technological development. An analysis of yield development confirms that for most annual crops yield increases lag behind area growth. Besides, the strong correlation could be explained by assuming rural population density to be a proxy for a range of other factors, like labour costs, or accessibility that are the direct drivers of land use change. In any case, this study suggests that for a specific--relatively coarse--window of temporal and spatial scale, land use patterns can be described with very simple relationships, with a strong contribution of population density. More local studies are needed to test the hypothesis that rural population density is a proxy for other variables.     

FORESTS AND OTHER FACTORS ASSOCIATED WITH STREAMFLOWS IN EAST TEXAS1

Effects of proportion of watersheds in forest and watershed physiographic factors on mean annual streamflow (1965-76), median flow, and 12 flood flow characteristics were regionally analyzed for 19 unregulated streams in East Texas. Annual streamflow increased with decreasing proportion of forest area. Differences in annual streamflow between full forest cover and bare watersheds could be as much as 200 mm. Other things being equal, the minimum watershed area required to generate 0.142 cm (5 cfs), a criterion used by the U.S. Corps of Engineering in regulating dredge and fill activity for water pollution abatement in East Texas streams, is 70 km² (27 mi²). Of the 31 physio-climatic parameters analyzed, watershed area, percent forest area, shape index, spring precipitation, and annual temperature were the most significant in affecting streamflow characteristics in East Texas. Using 2-3 of these five variables, all of the 14 streamflow characteristics can be estimated with accuracy ranging from acceptable to excellent levels.     

Mediterranean Coastal Sand Dune Vegetation: Influence of Natural and Anthropogenic Factors

The aim of the present work was to assess the conservation status of coastal dune systems in Tuscany (Italy). Emphasis was given to the presence and abundance of plant communities identified as habitat in accordance with the Directive 92/43/EEC. Twenty transects perpendicular to the shoreline were randomly positioned on the whole coastal area (30 km in length) in order to sample the full spectrum of plant communities. Vegetation zonation and relationships with the most frequent disturbance factors in the study area—beach cleaning, coastline erosion, presence of paths and roads, bathing settlements and trampling—were investigated through principal coordinate analysis and canonical correspondence analysis. Natural factors, such as distance from the sea and total length, were also considered. Differences in the conservation status of the sites were found, ranging from the total disappearance of the foredune habitats to the presence of the complete psammophilous (sand-loving) plant communities. Erosion, trampling, and paths were found to be closely correlated with degradation and habitat loss. Furthermore, the overall plant species diversity of dunes was measured with NH_Dune, a modified version of the Shannon index; while the incidence of invasive taxa was calculated using N, a naturalness index. However, these diversity indices proved to be a weaker bioindicator of ecosystem integrity than habitat composition along transects. A possible strategy for the conservation and management of these coastal areas could be to protect the foredunes from erosion and limit trampling through the installation of footbridges or the use of appropriate fences.     

Urban structure matters,even in a small town

A recent study in Frederikshavn, Denmark, shows that urban structural variables influence travel behaviour, even in a small town of around 30 000 inhabitants. As might be expected, socio-economic and attitudinal factors play a role in the respondents' travelling patterns. However, when controlling for these factors and a range of other potential explanatory variables, clear relationships are also found between urban structural characteristics and travel activity. These relationships exist across most subgroups of the population. The statistical relationships found between urban structure and travel behaviour are confirmed in qualitative interviews. The distance from the residence to the downtown area is a key factor influencing the accessibility to a number of facilities. These differences in accessibility result in corresponding differences in the actual travelling distances and modal split.     

A New Flood Index for Use in Evaluation of Local Flood Severity: A Case Study of Small Ungauged Catchments in Korea1

Ahn, Jae Hyun and Hyun Il Choi, 2013. A New Flood Index for Use in Evaluation of Local Flood Severity: A Case Study of Small Ungauged Catchments in Korea. Journal of the American Water Resources Association (JAWRA) 49(1): 1‐14. DOI: 10.1111/jawr.12025 Abstract: The aim of this article is to develop a new index measuring the severity of floods in small ungauged catchments for initial local flood information by the regression analysis between the new flooding index and rainfall patterns. Although a rapid local flood caused by heavy storm in a short period of time is now one of common natural disasters worldwide, such a sudden and violent hydrologic event is difficult to forecast. As local flooding rises rapidly with little or no advance warning, the key to local flood forecasting is to quickly identify when and where local flooding above a threshold is likely to occur. The new flooding index to characterize local floods is measured by the three normalized relative severity factors for the flood magnitude ratio, the rising curve gradient, and the flooding duration time, quantifying characteristics of flood runoff hydrographs. The new flooding index implemented for the two selected small ungauged catchments in the Korean Peninsula shows a very high correlation with logarithm of the 2‐h maximum rainfall depth. This study proposes 30 mm of rainfall in a 2‐h period as a basin‐specific guidance of precaution for the incipient local flooding in the two study catchments. It is expected that the best‐fit regression equation between the new flooding index and a certain rainfall rate can provide preliminary observations, the flood threshold, and severity information, for use in a local flood alert system in small ungauged catchments. Editor's note: This paper is part of a featured series on Korean Hydrology. The series addresses the need for a new paradigm of river and watershed management for Korea due to climate and land use changes.     

FACTORS AFFECTING FLOODS FROM WATERSHEDS IN HUMID REGIONS OF NORTHEASTERN OHIO1

This paper describes the results of a study of hydrologic factors affecting floods from humid region in northeastern Ohio. Statistical multiple correlation analysis was used to relate floods to hydrologic and basin characteristics. Results of the study emphasize that the characteristics of floods from small and large watersheds are so significantly different that the two problems cannot be combined into one solution. The studies show that the most important hydrologic characteristics in large watersheds were: drainage area size and main channel slope. For small watersheds the most important hydrologic characteristics were: drainage area size, rainfall intensity and soil index. For watershed effect by reservoir storage it was found that: (1) small drainage areas are relatively more affected by storage than large drainage areas; (2) storage of less than 25 acre feet per square mile will not have significant effect on the mean annual flood (for drainage area above 70 square miles).     

Summer total phosphorus in lakes: A map of Minnesota,Wisconsin, and Michigan,USA

A map of summer total phosphorus in lakes has been compiled for Minnesota, Wisconsin, and Michigan to clarify regional patterns in attainable lake trophic state. Total phosphorus was used as a measure of lake trophic state because: (1) phosphorus plays a central role in controlling the overall fertility of most lakes, (2) total phosphorus values are available for a great number of lakes, and (3) phosphorus is measured in a consistent manner. The maps were compiled using patterns of total phosphorus data and observed associations between these data and geographic characteristics including physiography, land use, geology, and soils. Regions depicted on the map represent areas of similarity in phosphorus concentrations in lakes, or similarity in the mosaic of values, as compared to adjacent areas. Within each region, differences in total phosphorus can be compared to natural and anthropogenic factors to determine the types of lakes representative of each region, the factors associated with differences in quality, and the realistically attainable phosphorus levels for each type of lake.     

An erosion-based land classification system for military installations

The universal soil loss equation (USLE) has been integrated with a geographic information system known as the geographical resources analysis support system (GRASS) to create a land classification system for use by military trainers and land managers to minimize the environmental impacts of military training activities. The USLE provides an estimate of current average annual sheet and rill erosion based upon factors representing climate, soil erodibility, topography, cover, and conservation support practices. The erosion estimate is compared to erosion tolerance values to produce an expression of the current erosion status. An index of inherent site erodibility is also achieved through manipulation of the USLE. Based on published soil surveys, satellite imagery, and ground-truth vegetation transects, data layers are created within GRASS for each of the component factors of the USLE. Appropriate mathematical operations are performed with the data layers, and color-coded maps are produced that represent the erosion status and erodibility index for each 50-m × 50-m area of soil surface. These maps aid military trainers and land managers in scheduling appropriate kinds and intensities of military training activities.     

DEVELOPMENT OF WATER QUALITY MANAGEMENT INDICES1

ABSTRACT: In a joint undertaking by The MITRE Corporation and the EPA Office of Water Programs Operations, three indices were developed: (1) An index of water quality; (2) An index of the need for abatement action; and (3) An index of the need for water quality management planning. These indices were evaluated for some 1000 planning areas (sub basins, regional planning jurisdictions, metropolitan areas, etc.) which together cover essentially all of the area of the 48 contiguous states.     

Regional analysis of climate, primary production, and livestock density in inner Mongolia

Overstocking is believed to be one of the principal causes for grassland degradation in northern China. For this reason, quantification of overstocking and spatiotemporal analysis are needed for this area. In this study, the relationship between annual rainfall and grassland aboveground net primary production (ANPP) was analyzed using data from 1982 to 1991 in the Inner Mongolia Autonomous Region (IMAR), China. Subsequently, rainfall-based livestock carrying capacity was estimated and combined with livestock density calculated from county-level livestock data from 1982 to 1991 to determine spatial and temporal patterns of a stocking rate index and its relationship with climatic factors. The results indicate the following. First, there was a significant linear relationship between annual rainfall and ANPP in IMAR and the slope of ANPP versus rainfall was greater than those found in South America and Africa, indicating higher rain-use efficiency. Second, temporally averaged livestock density showed overstocking in most of the rural counties except for those in the cold north, where human populations are low and transportation systems are poor. Third, the stocking rate index increased with temperature, from less than 1.0 in the north, to greater than 2.0 in most of the southern IMAR. Within the central IMAR, the index increased from west to east, along the gradient of increasing rainfall. Fourth, long-term dynamics of livestock density depicted continuous overstocking, more than 20%, from 1982 to 1991 along the western part of the NorthEast China Transect (NECT) within IMAR. Spatial planning of livestock densities according to carrying capacities and improved pastoral management are needed in this area.     

Sustaining appearances: sustainable development and the fisheries of Lake Victoria

The fisheries of Lake Victoria have undergone a major transformation over the last three decades. The character of the lake has been subject to the influence of many powerful factors including: substantial increases in fishing effort; growing integration into the global fish market; acceleration of anthropogenic activities in the catchment area; demographic change; the influence of adverse shifts in the climate; and introduction of exotic plant and animal species. The task of managing the lake's resources, therefore, has never been more daunting. This article argues that, in most cases, the authorities charged with achieving the goal of sustainable development for the fishery, have failed to address the symptoms—let alone the origins—of the current unsustainable tendencies embedded in the social, economic and political fabric of Lake Victoria's riparian States. It is these factors that directly impinge upon the success of management initiatives for the lake. The article argues that if sustainable development is to be achieved, then stakeholders must act in concert, eliminate unsustainable practices and reprogramme development plans to focus on realistic goals. A possible way forward will be to develop a participatory management system.     

1979—2006年泰安市建成区扩展特征及影响因素分析

在遥感和GIS技术支持下,采用扩展强度指数、紧凑度指数、象限分割方法研究了泰安市建成区1979—2006年的时空扩展变化特征及形态模式。结果表明,泰安市建成区自1979年以来呈现快速扩展趋势,建成区紧凑度指数呈现逐渐下降趋势。对自然和社会经济发展资料分析后认为,泰山对建成区北部的扩展形成天然屏障,而其他方位的快速扩展与泰安市固定资产投资、旅游业发展和人口增长等社会经济发展因素具有密切联系。针对紧凑度指数逐渐下降趋势,提出今后泰安市城市建设应当在城市合理布局的前提下,进一步加强土地的集约利用。     

Land Evaluation in a Salt-Affected Irrigated District Using an Index of Productive Potential

2 semiarid irrigated area with salt-affected soils. The available soil map is at 1:100,000 scale and its mapping units are used for the land evaluation with the FAO framework. These data are then elaborated using the index value method. This procedure gives a map of land evaluation units and a table that rates the productive potential of these units for six crops: alfalfa, barley, maize, rice, sunflower, and wheat.