An optimization approach for sustainable development planning of savanna systems

A savanna system is a natural ecosystem in which the competition between grass and woody vegetation in a semi-arid rangeland should be maintained for its sustainable development. Finding an optimal management plan for obtaining maximum economic profit from raising cattle without loss of sustainability of the savanna system during a planning period is a great challenge for rangeland managers. In this study, we formulate the sustainable development planning of the savanna system as an optimal control model, in which maximization of the stocking rate of cattle during the planning period is chosen as the objective while sustainable development requirements are achieved through the constraints represented by the desired final state of the system. Using Pontryagin's maximum principle, the model is transformed into a two-point boundary-value problem with nonlinear differential equations that is then solved using an iterative approach. An example with a specified desired final state in a savanna system without fire is used to demonstrate the performance of the model and the algorithm. Numerical experiments show that the planning strategy obtained from the optimal control model achieves maximum economic profit from raising cattle during the planning period and simultaneously improves the resilience of the system and maintains sustainable development of the rangeland. The outcomes demonstrate that resilience, sustainable development and economic profit are consistent concepts in optimal management strategy for rangeland management.     

A geomorphological approach to sustainable planning and management of the coastal zone of Kuwait

The coastal zone in Kuwait has been under a considerable pressure from conflicting land uses since the early 1960s, as well as from the destruction and oil pollution caused by the Gulf War. To avoid further damage and to protect the coastal heritage it is essential to adopt an environmentally sustainable management process. This paper shows how the study of coastal geomorphology can provide a sound basis for sustainable planning and management. Based on coastal landforms, sediments and processes, the coastline of Kuwait was divided into nine geomorphic zones. These zones were grouped into two main geomorphic provinces. The northern province is marked by extensive muddy intertidal flats and dominated by a depositional and low-energy environment. The southern geomorphic province is characterised by relatively steep beach profiles, rocky/sandy tidal flats and a moderate to high-energy environment. The study has demonstrated that pollution, benthic ecology and other environmental conditions of the coast are a function of coastline geomorphology, sedimentology and related processes. The geomorphological information was used to determine the coastal vulnerability and to assess the environmental impacts of development projects and other human activities. Several strategies were outlined to integrate the geomorphic approach into the management of the coastal resources.     

中国各省区经济增长溢出分析

本文基于新增长理论,考虑空间相互作用的衰减性和溢出与GDP缺口的关系,改进了Conley、Ligon(2003)建立的区域溢出统计分析模型。基于这个模型,计算分析了中国各省区的GDP溢出。分析表明:中国大部分省区的增长溢出是正的,上海对外的增长溢出最大。在中国中部地区,湖北省具有重要的溢出作用。中国西部地区除云南、新疆外,经济溢出基本上是负的。因此推广它们的经验,促进西部经济与东部一体化是重要的发展战略。分析还建议,将给予新疆的某些政策也给予东北地区,可能是振兴东北老工业基地的有效措施。     

我国环境生态形势研究的一种方法

在分析国内外环境生态形势研究现状的基础上,结合我国的环境生态形势特征,综合自然、社会、经济因素,构建了评价我国环境生态形势的指标体系,建立各指标计算的数学模型,在地理信息系统和数据库管理系统支持下以全国县域为单元进行多因素综合性定量研究,采用指标权重的地域计算方法来反映区域差异,得出了全国各县的环境生态形势指标值,并绘制出我国环境生态形势图。     

An asymptotic approach to the inversion of free oscillation data

Summary. A technique is suggested for the non-linearized inversion of subsets of free oscillation periods which are short enough that their asymptotic properties may be exploited. The general background of the method for monotonic and non-monotonic velocity distributions are described and applications to torsional and spheroidal free oscillation data are suggested. The advantages of joint analysis of travel times and free oscillation periods as a single data stream for non-linearized inversion are discussed.     

An information systems approach to the preservation of biological diversity

Abstract

Although biological diversity has emerged in the 1980s as a major scientific and political issue, efforts at scientific assessment have been hampered by the lack of cohesive sets of data. We describe, in concept, a comprehensive national diversity information system, using geographical information system (GIS) techniques to organize existing data and improve spatial aspects of the assessment. One potential GIS analysis, to identify gaps in the network of nature reserves for California, is discussed in greater detail. By employing an information systems approach, available data can be used more effectively and better management strategies can be formulated.     

A micro-level approach to rural development planning: the case of piped water in Sierra Leone

This study addresses the need to incorporate analysis of the target area and the target population at the micro level as part of plan implementation strategies in less developed countries, especially in Africa. Such micro-level studies have several benefits, amongst which are the ease and low costs of data compilation and the potential for local input. To demonstrate these points, the proposed government distribution of water supply facilities in two villages in Sierra Leone, West Africa, is compared with an alternative distribution. While the government strategy attempts to maximize areal coverage, the alternative distribution attempts to minimize walking distance. It is shown that accessibility to the water supply facilities can be improved under the alternative approach.     

An application-driven approach to terrain model construction

Terrain is a surface phenomenon that is measured, modelled, and mapped. However, it is continuously variable and must be simulated by points or mathematical equations that are inherently approximations. The error induced by digitally represented terrain can propagate to surface derivatives and geographical information science (GIS) applications where topography is considered. This can lead to uncertainty in model predictions and the use of data that are unfit for the application to which they are intended. This article outlines the problem of uncertainty in terrain representation and demonstrates the consequences for volcanic mudflow modelling. The response of a simple least-cost single flow algorithm to input parameters was investigated in order to assess output variation from the different sources of input variation. Elevation error was modelled with a probability density function (PDF) and propagated through stochastic simulation (Monte Carlo). Such combined uncertainty and sensitivity analyses enabled a qualitative judgement of the relative significance of elevation error on the flow model prediction. Different methods for terrain model construction were considered and show that supplementing global positioning system (GPS) measurements with information from field notes and reconnaissance photographs greatly improved the model performance and reduced the uncertainty. It is concluded that in terms of validity of model results, there is no substitute for constructing an elevation model that is informed by the terrain.     

荒漠化分类分级理论的初步探讨

简要回顾了二十多年来联合国荒漠化代表性分类分级理论的发展,评价了1977年、1984年、1992年和1997年提出的最有代表性分类分级理论,归纳出目前三种分类分级理论的评价思想:以指标体系为基础的绝对退化评价,生产力与经营水平相结合的相对退化评价和以生态系统中植被土壤地形差异退化为依据的多样性评价。在对比分析的基础上,针对各体系存在的问题,指出通过荒漠化退化生态基准的恢复和确定可提高分类分级理论的科学性与权威性,并提出确定时间尺度和空间类型的初步建议。     

An approach to the problem of coastal erosion in quaternary sediments

Approximately 40 per cent of the shorelines of the lower Great Lakes are backed by relatively weak Quaternary sediments, and similar shorelines are found on many middle and high-latitude coasts. The high rates of bluff recession which are characteristic of these areas lead to economic losses through erosion of land and damage to buildings, and may prompt a wide range of measures designed to reduce erosion and protect property. Assessment of the physical problem and of possible solutions to it can best be achieved through a sediment budget approach. This is illustrated through a case study of an area near Grimsby, Ontario. The volume of sediment supply to the beach was calculated from measurements of bluff height and annual recession rates. The potential volume of longshore sediment transport was determined from the wave climate of the area and computer modelling of wave refraction. The relationship between sediment supply and potential transport rate can be used to assess the magnitude of the sediment deficit or surplus at points along the shoreline, and this provides an insight into the controls on alongshore variations in recession rates.     

A synoptical delimitation of geographical didactics

Biilmann, Ove: A Synoptical delimitation of geographical didactics Gcografisk Tidsskrift 82: 5–10. Copenhagen, June 1. 1982.

A synoptical delimitation of geographical didactics which relate to geographical tradition, academical geography, genera! pedagogy and practical teaching.     

An evaluation of foreign planning assistance to Tanzania's decentralized regional planning programme, 1972–81

The paper describes: (i) the structure of administrative decentralization, to regional level and below, which has been adopted in Tanzania since 1972; (ii) the pattern of foreign technical and capital assistance provided to date, and (iii) the major problems encountered in practice.     

我国都市圈理论研究与规划实践中的若干误区

随着我国城市化进程的加快,在长江三角洲、京津冀、珠江三角洲和辽中南等经济社会发展水平最高的地区,大城市的地域空间组织开始从单体型城市的简单形态,向以中心城市为核心的诸多城市和地区相互交融形成的都市圈的复杂形态转变。大上海、大北京、大广州、大沈阳等大都市圈的雏形已经初步形成,同时在一些经济发展水平较高的大中城市的周边地区,一些区域性都市圈和地方性都市圈也在逐渐形成。以这些中心城市为核心的都市圈的形成与发展,对区域经济社会的发展起到了越来越重要的支撑作用。借鉴发达国家的经验,实施都市圈的发展战略已经成为一个共识。正确引导都市圈的建设与发展是我国新形势下城市发展的一个重要课题。本文指出了我国目前都市圈理论研究和规划实践上存在的一些误区,对都市圈的基本概念、地域本质、形成机理、地域结构与空间形态、类型与规模等进行了分析,为我国21世纪都市圈的建设与发展提供科学的理论依据。     

An algebraic approach to automated geospatial information fusion

This paper presents a new technique for information fusion. Unlike most previous work on information fusion, this paper explores the use of instance‐level (extensional) information within the fusion process. This paper proposes an algorithm that can be used automatically to infer the schema‐level structure necessary for information fusion from instance‐level information. The approach is illustrated using the example of geospatial land‐cover data. The method is then extended to operate under uncertainty, such as in cases where the data are inaccurate or imprecise. The paper describes the implementation of the fusion method within a software prototype. Finally, the paper discusses several key topics for future research, including applications of this work to spatial‐data mining and the semantic web.     

区域经济地理学方法论建设初探

区域经济地理学方法论建设落后于学科实践和理论研究的进展,有必要处理好方法论与实践、理论及相邻学科的关系,寻求一般研究方法与学科具体方法的有机结合,健全并规范学科分支内容的研究方法,使之形成面向实践的方法体系。应通过借鉴吸收横断学科、相邻学科方法,应用现代技术手段,建设符合学科实践和理论发展要求的方法论。     

An approach to the design principles for indicator system of desertification degree

Over the past 20 years great progress has been made in the desertification study, however the general tendency of desertification development worldwide has not been radically reversed, oppositely in some regions desertification remains in an expansion stagte. Accordingly, the desertification study is still an arduous and long-term task facing the world today. As one of the central problems of the desertification study, the indicator system for desertification degree still requires further perf…     

An automated approach to the classification of the slope units using digital data

Digital elevation and remote sensing data sets contain different, yet complementary, information related to geomorphological features. Digital elevation models (DEMs) represent the topography, or land form, whereas remote sensing data record the reflectance/emittance, or spectral, characteristics of surfaces. Computer analysis of integrated digital data sets can be exploited for geomorphological classification using automated methods developed in the remote sensing community. In the present study, geomorphological classification in a moderate- to high-relief area dominated by slope processes in southwest Yukon Territory, Canada, is performed with a combined set of geomorphometric and spectral variables in a linear discriminant analysis. An automated method was developed to find the boundaries of geomorphological objects and to extract the objects as groups of aggregated pixels. The geomorphological objects selected are slope units, with the boundaries being breaks of slope on two-dimensional downslope profiles. Each slope unit is described by variables summarizing the shape, topographic, and spectral characteristics of the aggregated group of pixels. Overall discrimination accuracy of 90% is achieved for the aggregated slope units in ten classes.     

Fighting for a future: an actor-oriented planning approach to landscape preservation in Galicia

Modification and channelization of streams and rivers have been conducted extensively throughout the world during the past century. Subsequently, much effort has been directed at re-creating the lost habitats and thereby improving living conditions for aquatic organisms. However, as restoration methods are plentiful, it is difficult to determine which one to use to get the anticipated result. The aim of this study was to compare two commonly used methods in small Danish streams to improve the physical condition: re-meandering and passive restoration through cease of maintenance. Our investigation included measurement of the physical conditions in 29 stream reaches covering four different groups: (1) re-meandered streams, (2) LDC streams (the least disturbed streams available), (3) passively restored streams (>10?years stop of maintenance) and (4) channelized and non-restored streams. The in-stream habitats were compared through analysis of the measured physical parameters and by applying a habitat model. We found that re-meandering is a more effective way of re-creating near-natural physical conditions in small streams compared to passive restoration. This is probably due to the limited energy in small streams which restricts re-shaping of the stream channel. However, based on habitat suitability modelling, the change to the physical condition did not translate into improved habitat suitability for young of the year brown trout highlighting the value of using several methods when evaluating restoration success.     

在全球一体化形势下中国农业持续发展面临的困境与对策

在全球一体化的形势下，中国农业持续发展面临重重困境：（1）耕地面积减少，耕地质量下降；（2）水资源短缺，供需矛盾突出；（3）生态环境问题日益严重；（4）粮食与食物安全问题不容忽视；（5）科技竞争在国际上处于劣势地位；（6）生产成本过高，收益过低，农民的生产积极性受到了伤害；（7）农村剩余劳动力的充分就业是一个难题，面对这些困境，中国农业持续发展应该采取的对策是；（1）合理利用水土资源，保护生态环境，促进资源环境与农业经济的协调发展；（2）继续深化农村经济体制改革，构筑新的农业政策体系；（3）加速农业科技创新与科技进步的步伐。     

An alternative approach to transverse and profile terrain curvature

Terrain curvature is one of the most important parameters of land surface topography. Well-established methods used in its measurement compute an index of plan or profile curvature for every single cell of a digital elevation model (DEM). The interpretation of these outputs may be delicate, especially when selected locations have to be analyzed. Furthermore, they involve a high level of simplification, contrasting with the complex and multiscalar nature of the surface curvature itself. In this paper, we present a new method to assess vertical transverse and profile curvature combining real-scale visualization and the possibility to measure these two terrain derivatives over a large range of scales. To this purpose, we implemented a GIS tool that extracts longitudinal and transverse elevation profiles from a high-resolution DEM. The performance of our approach was compared with some of the most commonly used methods (ArcMap, Redlands, CA, USA; ArcSIE, Landserf) by analyzing the terrain curvature around charcoal production sites in southern Switzerland. The different methods produced comparable results. While conventional methods quickly summarize terrain curvature in the form of a matrix of values, they involve a loss of information. The advantage of the new method lies in the possibility to measure and visualize the shape and size of the curvature, and to obtain a realistic representation of the average curvature for different subsets of spatial points. Moreover, the new method makes it possible to control the conditions in which the index of curvature is calculated.