REGIONAL FLOOD FREQUENCY ANALYSIS IN SOUTHERN ONTARIO USING L-MOMENTS

Annual flood series from unregulated rivers in southern Ontario are examined with a view to testing the efficacy of the generalized extreme value distribution to represent all flood frequency characteristics in the area. Series are characterized by their sample L-moments, the higher orders of which are more reliable than product moments, facilitating both the selection of the appropriate probability distribution and the estimation of its necessary parameters. The generalized extreme value distribution is found to provide a good fit to the diversity of annual flood characteristics found in the area and to furnish a reasonable regional flood frequency distribution. The spatial variations of the derived parameters may be successfully explained in terms of potential geographic and hydrologic controls on precipitation input, flood generating processes (snowmelt or rainfall), and land use     

LAND PRICES IN ESSEX COUNTY, ONTARIO 1798 TO 1852

This paper examines land prices in Essex County, Ontario, for the period to 1825 and from 1826 to 1852 in terms of overall accessibility to market and the physical environment. The prime source material was the Abstract Index to Deeds , and data drawn from this source were used in a series of multiple regression analyses. The results confirm the importance of accessibility. However, the physical environment did not affect land prices significantly. The article concludes by considering future refinements of the analysis.
L'article examine les prix des terres dans le comté d'Essex, Ontario pour la période jusqu'à 1825 et de 1826 à 1852 en ce qui concerne I'accessibilité générale, I'accessibilité au marché et I'environnement physique. La source principale de la recherche était l' Abstract Index to Deeds et les données de éette source étaient utilisées dans des regressions multiples. Les résultats affirment l'importance de l'accessibilité. Pourtant, l'environnement physique n'a pas eu une influence significantive sur les prix des terres. L'article se termine en considérant des ragginements futurs pour l'analyse.     

山西省农业土地资源可持续利用研究

农业土地资源的可持续利用是实现农业可持续发展的基础和保证。本文通过分析山西农业土地资源的特点,开发利用现状及存在的主要问题,提出了山西农业土地资源可持续利用的主要措施:加快退耕还林步伐,调整农业用地结构,优化农业生态环境;加强生态农业建设,合理利用土地资源,提高土地生产率;加大农业生态环境整治力度,防止土地退化,减轻自然灾害;强化土地管理,规范土地市场,保护农业土地资源。     

HYDROLOGICAL RESPONSE TO REFORESTATION IN THE GANARASKA RIVER BASIN, SOUTHERN ONTARIO

Headwater slopes of the Ganaraska River basin in southern Ontario were reforested after World War II in an effort to reduce soil erosion and downstream flooding. Hydrological responses to this land use change are examined. Between 1945 and 1990 forest cover in Ganaraska Forest increased from 3.3 to 8.9% of the basin area. Over this period annual runoff decreased by 100 mm, and runoff ratios were reduced. These hydrological changes exceed those predicted from empirical relationships between runoff and forest cover, and likely reflect a combination of increased interception and evapotranspiration, water storage in headwater aquifers, and deep groundwater losses. Reforestation was also associated with significant decreases in high flows and increases in annual minimum daily flows. Annual maximum daily mean specific discharges decreased from 0.36 to 0.11 m³ s^-1 km^-2 (±0.0009 m³ s^-1 km^-2) between 1946 and 1962, while annual maximum daily mean specific discharges decreased from 0.0037 to 0.0062 m3 s-1 km^-2 (±0.10 m³ s^-1 km^-2) between 1957 and 1990, as estimated from bestfit regression relationships. The response of runoff ratios and peak flows to increased forest cover was more rapid than that of minimum daily flows. Results suggest that hydrological responses to relatively minor modifications of forest cover can be detected, depending on location of land use change within the basin. Les pentes des sources du bassin de la Rivère Ganaraska dans le Sud de I'Ontario ont été reboisées après la deuxième guerre mondiale pour diminuer l'érosion du sol et les inondations en aval. Les réponses hydrologiques au changement dans l'utilisation du sol sont examinées. Entre 1945 et 1990, la couverture de la forêt de Ganaraska s'est accrue de 3,3 à 8,9% par rapport à la superficie du bassin. Durant cette période, le ruissellement annuel a diminué de 100 mm et les proportions de ruissellement furent réduites. Ces changements hydrologiques dapassent ceux prédits par les relations empiriques entre les débits et la couverture forestère et ils reflètent probablement les effets combinés de l'augmentation d'interception et évapotranspiration, de I'entreposage d'eau dans les nappes aquifères en amont bassin et de pertes importantes d'eaux des sources. Le reboisement éait aussi associéà une diminution considérable des hauts deébits et à une augmentation des débits minimum journaliers annuels. Le maximum annuel des deébits spécifiques journaliers moyens a diminué de 0,36 à 0,11 m³ s^-1 km^-2 (±0,10 m³ s^-1 km^-2) entre 1946 et 1962 pendant que le minimum annuel des deébits spécifiques journaliers moyens a augmenté de 0,0037 à 0,0062 m³ s^-1 km^-2 (±0,0009 m³ s^- km^-2) entre 1957 et 1990, tel qu'estiméà partir d'équations de régression. La réponse des proportions de ruissellements et des écoulements de points a l'augmentation de la couverture forestière était plus rapide que celle des débits minimum journaliers. Ces résultats laissent entendre que les réponses hydrologiques suite à des modifications mineures peuvent être dètectées selon l'emplacement de ces changements à l'intérieur du bassin.     

基于GIS的西安市南郊土地城市化空间发展研究

城市化发展所带来的社会经济的剧烈变动,促使城乡地域土地利用的根本性变革,并由此引发农村和城市协调发展等问题。城市化的过程也是一种土地利用的变动过程。伴随着城市化,土地利用问题日益成为影响城市化发展的关键。本研究选取西安市南郊为研究区,利用覆盖西安市的SPOT遥感影像,结合相关文献、资料,在解译的基础上获得1996年和2006年西安市南郊土地利用数据。通过分析对比可知,土地利用面积变化和类型改变对城郊经济结构以及社会活动都产生了巨大影响。为了实现城乡结合部的土地可持续利用,文中深入剖析了土地不可持续利用问题,进而提出了相应的对策建议。     

ON HANDLING URBAN INFORMALITY IN SOUTHERN AFRICA

In this article I reconsider the handling of urban informality by urban planning and management systems in southern Africa. I argue that authorities have a fetish about formality and that this is fuelled by an obsession with urban modernity. I stress that the desired city, largely inspired by Western notions of modernity, has not been and cannot be realized. Using illustrative cases of top–down interventions, I highlight and interrogate three strategies that authorities have deployed to handle informality in an effort to create or defend the modern city. I suggest that the fetish is built upon a desire for an urban modernity based on a concept of formal order that the authorities believe cannot coexist with the “disorder” and spatial “unruliness” of informality. I question the authorities' conviction that informality is an abomination that needs to be “converted”, dislocated or annihilated. I conclude that the very configuration of urban governance and socio‐economic systems in the region, like the rest of sub‐Saharan Africa, renders informality inevitable and its eradication impossible.