Topography is the most factor that has the greatest impact of all factor that affect the distribution. To study the diversity of trees and shrub species in the Perc forest situated in Khorramabad, Lorestan, 140 circul...Topography is the most factor that has the greatest impact of all factor that affect the distribution. To study the diversity of trees and shrub species in the Perc forest situated in Khorramabad, Lorestan, 140 circular plots of 1200 m2 in a grid of 300 m × 250 m were surveyed, using a systematic random sampling method. In each plot, the Margalef richness index, Shannon-Wiener diversity index, Hill＇s N1 and Simpson indices and the evenness index of Simpson and Smith-Wilson were calculated and ordered on the basis of different classes of elevation, exposition and slope. The results indicated that slope did not have any significant effect on the indices. Exposition and elevation classes significant impacted the richness and diversity indices, but did not influence evenness. In general, the highest plant diversity was observed for slopes less than 15 %, northern aspects, without geographical direction, and elevations of 2100-2200 m. This information can be very useful in achieving the goals for sustainable management of forests. In addition to greater protection for regions with high diversity and reforestation （compatible species） in degraded area, we can help increase diversity in forests.展开更多
The soil resources of Sierra Leone remain an integral part of sustainable agricultural development but knowledge of the suitability of soils and their management requirements for a variety of land uses is still lackin...The soil resources of Sierra Leone remain an integral part of sustainable agricultural development but knowledge of the suitability of soils and their management requirements for a variety of land uses is still lacking to a greater extent. In this view, a detailed soil survey of three chiefdoms in Northern Sierra Leone was undertaken to evaluate the genesis of soils and interpret soil-landscape properties and their relationships using the toposequence and free style approach of soil survey. Three major soil types, viz, gravelly, gravel-free over gravel and gravel-free soils, formed either directly or indirectly from weathered and disintegrated parent materials of two geologic origins namely Rokel River Series (comprising of sandstone, shale and mudstone), and Granite and Acid Gneiss were identified. The gravelly soils are formed from sandstone and sandy shales of the Rokel River Series, which upon weathering released iron and hydrated oxides that hardened into plinthite upon drying. The gravel-free over gravel soils are formed from acid gneiss containing acid and intermediate igneous and metamorphic rocks, which upon weathering produced sandy clay textured soils whereas the gravel-free soils are derived from sedimentary rocks (shales and mudstones) of Rokel River Series, which upon weathering and action of organisms produced sandy clay loam and sandy clay textured soils. The gravel-free over gravel soils are mostly located in the summit and back slopes and show dark brown to dark yellowish-brown hue and moderate chroma, weak to moderate structure and absence of coarse fragments in the 0 - 40 cm layer, and a strong brown hue and high chroma, very weak fine angular blocky structure having abundance of coarse fragments from 40 cm and above. In these soils, the compactness of ironstone and sandstone gravels increases with depth. The gravel-free soils are found on three landscape positions, viz, back slopes, foot slopes and toe slopes. On the back and foot slopes, the soils are characterized by very dark brown to dark展开更多
Bibliometrics was used to statistically analyze key zones within the Yangtze River Basin(YRB)funded by the National Natural Science Foundation of China(NSFC)and national ministries over the past 20 years.This study de...Bibliometrics was used to statistically analyze key zones within the Yangtze River Basin(YRB)funded by the National Natural Science Foundation of China(NSFC)and national ministries over the past 20 years.This study determined that funds that derived from national ministries have mainly focused on issues related to environmental pollution,ecological security,technological water regulations,and river basin ecosystems,which offer a better understanding of the national requirements and the scientific knowledge of the YRB in combination with data from the NSFC.Under a background of bolstering the construction of green ecological corridors in the economic belt of the YRB,this study proposes future conceptual watershed research initiatives in this region as a study objective by reinforcing the implementation of the Chinese Ecosystem Research Network(CERN)and by emphasizing the use of new technologies,new methods,and new concepts for the prospective design of frontier research under the perspective of geoscience and earth system science.This study promotes large-scale scientific field and research objectives based on big science and big data.展开更多
The physiographic characterization of a basin is a fundamental element as it defines the hydrological behavior of that basin. The present work deals with the development and implementation of a tool that allows calcul...The physiographic characterization of a basin is a fundamental element as it defines the hydrological behavior of that basin. The present work deals with the development and implementation of a tool that allows calculating in an automated manner the physiographic parameters of a basin, as well as those of the surface runoff and main river, besides other graphic elements: hypsometric curve, equivalent rectangle and profile of the main river. Such a tool was developed under Visual Basic 6 programming language and the spatial geographic component ArcObjects by ESRI;they enabled the development of a library as a final product (.dll), which can be loaded and implemented in ArcMap software. In the methodology a Conceptual Model was established, from which it was possible to identify the requirements and methods to obtain the parameters, as well as the conception and implementation of the Logical Model that includes the specific functions and also the input structures, processes and data output. Finally, the tool was tested with actual data from El Caracol river basin, located in central-southern Mexico, which showed the easiness and usefulness of it, besides the effectiveness of the results, not leaving aside the time and resources saved by the user when characterizing a basin, compared with other conventional processes.展开更多
This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscap...This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscape in Nigeria. Information was gathered on the various aspects of the landscape, including the Geology, Physiography (Relief) and Geomorphology, Geomorphic processes, Weathering, Drainage processes, Landforms, Surface Water Hydrology and Water Resources. The Benin Region is underlained by sedimentary formation of the South Sedimentary Basin. The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand. Geologically, the Benin Region comprises of 1) the Benin formation;2) alluvium;3) drift/top soil and 4) Azagba-Ogwashi (Asuba-Ogwashi) formation. Several parts of the region are surrounded by the Benin historical moats. The region has been described as a tilled plain in the south western direction. The local relief of the region is 91 m. Boreholes records in the Benin Region show evidence of deep chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth as found in the borehole drilled in the region. These are products of deep chemical decay of the original parent rock materials. Three river systems drain the Benin Region. They are the Ikpoba River, the Ogba River and Owigie-Ogbovben River systems. The mean annual discharge of Ikpoba River for 1982-1983 and 1993-2002 was 1411 mm/yr, which was 1.019 × 10<sup>9</sup> m<sup>3</sup> with a mean annual baseflow of 1256.23 mm (0. 907 × 109 m<sup>3</sup>). This constitutes 87.65% of the total flow. It has a mean annual surface runoff of 225.18 mm (0.112 × 10<sup>9</sup> m<sup>3</sup>) or 24.4 % of the total discharge. The water resources of the region include surface water and underground water.展开更多
文摘Topography is the most factor that has the greatest impact of all factor that affect the distribution. To study the diversity of trees and shrub species in the Perc forest situated in Khorramabad, Lorestan, 140 circular plots of 1200 m2 in a grid of 300 m × 250 m were surveyed, using a systematic random sampling method. In each plot, the Margalef richness index, Shannon-Wiener diversity index, Hill＇s N1 and Simpson indices and the evenness index of Simpson and Smith-Wilson were calculated and ordered on the basis of different classes of elevation, exposition and slope. The results indicated that slope did not have any significant effect on the indices. Exposition and elevation classes significant impacted the richness and diversity indices, but did not influence evenness. In general, the highest plant diversity was observed for slopes less than 15 %, northern aspects, without geographical direction, and elevations of 2100-2200 m. This information can be very useful in achieving the goals for sustainable management of forests. In addition to greater protection for regions with high diversity and reforestation （compatible species） in degraded area, we can help increase diversity in forests.
文摘The soil resources of Sierra Leone remain an integral part of sustainable agricultural development but knowledge of the suitability of soils and their management requirements for a variety of land uses is still lacking to a greater extent. In this view, a detailed soil survey of three chiefdoms in Northern Sierra Leone was undertaken to evaluate the genesis of soils and interpret soil-landscape properties and their relationships using the toposequence and free style approach of soil survey. Three major soil types, viz, gravelly, gravel-free over gravel and gravel-free soils, formed either directly or indirectly from weathered and disintegrated parent materials of two geologic origins namely Rokel River Series (comprising of sandstone, shale and mudstone), and Granite and Acid Gneiss were identified. The gravelly soils are formed from sandstone and sandy shales of the Rokel River Series, which upon weathering released iron and hydrated oxides that hardened into plinthite upon drying. The gravel-free over gravel soils are formed from acid gneiss containing acid and intermediate igneous and metamorphic rocks, which upon weathering produced sandy clay textured soils whereas the gravel-free soils are derived from sedimentary rocks (shales and mudstones) of Rokel River Series, which upon weathering and action of organisms produced sandy clay loam and sandy clay textured soils. The gravel-free over gravel soils are mostly located in the summit and back slopes and show dark brown to dark yellowish-brown hue and moderate chroma, weak to moderate structure and absence of coarse fragments in the 0 - 40 cm layer, and a strong brown hue and high chroma, very weak fine angular blocky structure having abundance of coarse fragments from 40 cm and above. In these soils, the compactness of ironstone and sandstone gravels increases with depth. The gravel-free soils are found on three landscape positions, viz, back slopes, foot slopes and toe slopes. On the back and foot slopes, the soils are characterized by very dark brown to dark
基金The Major Science and Technology Program for Water Pollution Control and Treatment,No.2017ZX07101-001National Natural Science Foundation of China,No.41922003,No.41871080。
文摘Bibliometrics was used to statistically analyze key zones within the Yangtze River Basin(YRB)funded by the National Natural Science Foundation of China(NSFC)and national ministries over the past 20 years.This study determined that funds that derived from national ministries have mainly focused on issues related to environmental pollution,ecological security,technological water regulations,and river basin ecosystems,which offer a better understanding of the national requirements and the scientific knowledge of the YRB in combination with data from the NSFC.Under a background of bolstering the construction of green ecological corridors in the economic belt of the YRB,this study proposes future conceptual watershed research initiatives in this region as a study objective by reinforcing the implementation of the Chinese Ecosystem Research Network(CERN)and by emphasizing the use of new technologies,new methods,and new concepts for the prospective design of frontier research under the perspective of geoscience and earth system science.This study promotes large-scale scientific field and research objectives based on big science and big data.
文摘The physiographic characterization of a basin is a fundamental element as it defines the hydrological behavior of that basin. The present work deals with the development and implementation of a tool that allows calculating in an automated manner the physiographic parameters of a basin, as well as those of the surface runoff and main river, besides other graphic elements: hypsometric curve, equivalent rectangle and profile of the main river. Such a tool was developed under Visual Basic 6 programming language and the spatial geographic component ArcObjects by ESRI;they enabled the development of a library as a final product (.dll), which can be loaded and implemented in ArcMap software. In the methodology a Conceptual Model was established, from which it was possible to identify the requirements and methods to obtain the parameters, as well as the conception and implementation of the Logical Model that includes the specific functions and also the input structures, processes and data output. Finally, the tool was tested with actual data from El Caracol river basin, located in central-southern Mexico, which showed the easiness and usefulness of it, besides the effectiveness of the results, not leaving aside the time and resources saved by the user when characterizing a basin, compared with other conventional processes.
文摘This paper examines the geomorphology and hydrology of the Benin Region, Edo State, Nigeria. The major landform features and processes of the region are highlighted. This region is a strategic and significant landscape in Nigeria. Information was gathered on the various aspects of the landscape, including the Geology, Physiography (Relief) and Geomorphology, Geomorphic processes, Weathering, Drainage processes, Landforms, Surface Water Hydrology and Water Resources. The Benin Region is underlained by sedimentary formation of the South Sedimentary Basin. The geology is generally marked by top reddish earth, composed of ferruginized or literalized clay sand. Geologically, the Benin Region comprises of 1) the Benin formation;2) alluvium;3) drift/top soil and 4) Azagba-Ogwashi (Asuba-Ogwashi) formation. Several parts of the region are surrounded by the Benin historical moats. The region has been described as a tilled plain in the south western direction. The local relief of the region is 91 m. Boreholes records in the Benin Region show evidence of deep chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth as found in the borehole drilled in the region. These are products of deep chemical decay of the original parent rock materials. Three river systems drain the Benin Region. They are the Ikpoba River, the Ogba River and Owigie-Ogbovben River systems. The mean annual discharge of Ikpoba River for 1982-1983 and 1993-2002 was 1411 mm/yr, which was 1.019 × 10<sup>9</sup> m<sup>3</sup> with a mean annual baseflow of 1256.23 mm (0. 907 × 109 m<sup>3</sup>). This constitutes 87.65% of the total flow. It has a mean annual surface runoff of 225.18 mm (0.112 × 10<sup>9</sup> m<sup>3</sup>) or 24.4 % of the total discharge. The water resources of the region include surface water and underground water.
