Gezira Scheme between state and market: some remarks on the privatization of irrigation in Sudan

This paper is a study of so-called privatization of the great Sudanese Gezira Scheme, under the structural and budgetary problems of the country. Nothwithstanding the official declaration, in reality privatization affected the project just in nominal way. Indeed, two factors play against it: the resistance of the State, which wants to hold the management of the national strategic resources, and the resistance of the territory itself which — as autopoietic system — reacts against any attempt to change its own structure. The islamic renewal(tajdid) can be considered as a way to solve the dilemma between development and social consent, under these new conditions.     

NDVI dynamic changes and their relationship with meteorological factors and soil moisture

Normalized difference vegetation index (NDVI) is an important indicator for measuring vegetation coverage, which is of great significance for evaluating vegetation dynamics and vegetation restoration. It can clearly analyze the suitable growth condition of vegetation by studying the relationship between meteorological factors, soil moisture and NDVI. Based on MODIS/NDVI data, the spatio-temporal characteristics of vegetation coverage in the Weihe River Basin (WRB) were analyzed by the trend analysis method. The relationship of NDVI with meteorological factors and NDVI with soil moisture simulated by the soil and water assessment tool (SWAT) model was analyzed in this paper. The results show that NDVI values gradually change with an increase from north to south in the WRB. The maximum of the average monthly NDVI is 0.702 (August) and the minimum is 0.288 in February from 2000 to 2015. The results of the seven grades of NDVI trend line slope indicate that the improvement area of vegetation coverage accounts for 30.93% of the total basin, and the degradation area and basically unchanged area account for 23% and 42.9%, respectively. The annual mean soil moisture is 19.37% in the WRB. There was a strong correlation between NDVI and precipitation, temperature, evaporation and soil moisture, and the correlation coefficients were 0.78, 0.89, 0.71 and 0.65, respectively. The ranges of the most suitable growth conditions for vegetation are 80–145 mm (precipitation), 13–23 °C (temperature), 94–144 mm (evaporation) and 25–33% (soil moisture), respectively.     

Dry years and their relationship to crop production in Sri Lanka

Drought is a distinct agroclimatological hazard with far reaching consequences upon crop production. Among them, famines are regarded the most serious effects of climatological drought. Although there is no doubt about the principally valid relationship between drought and production losses it seems more problematic how this relationship can be proved statistically. In this paper annual rainfall data and production figures of the three major crops of Sri Lanka, rice (paddy), tea and rubber, are correlated, but only partially a true relationship between dry years and production losses could be observed. Reason for this may be the moderate degree of annual drought. From the results shown, the question arises how agricultural drought can be defined and how the climatic effects upon crop production can be studied satisfactorily.     

The relationship between urbanization and socio-economic development in the Sudan

The study of urbanization has, in recent years, assumed increasing importance in developing countries not only because these countries are in the process of facing rapid urbanization, but also because the process of urbanization has been recognized as a part of a larger process of economic and social change which is affecting the rural areas.     

Compositional characteristics of garnets and pyroxenes in contact-metasomatic skarn deposits and their relationship with metallization

The compositions of more than 300 granets and pyroxenes from 14 contact-metasomatic calcic skarn deposits and calcic-magnesia skarn skarn deposits in China have been examined using electron microprobe technique. The compositions of garnets and pyroxenes from a wide variety of ore types represent ten major classes of calcic skarn deposits (Fe, Fe-Cu, Pb-Zn,W, Sn, Sn-Mo-Bi-W, W-Bi-Cu-Mo, Cu-Zn and W-Zn-Cu) and three major classes of calcic-magnesia skarn deposits (Fe-Cu, Mo, Pb-Zn). Garnets and pyroxenes show a wide range of variation in composition, but the majority of garnets are grossular-andradite solid solutions containing less than 15 mol% (spessartine + almandine + pyrope), whereas most pyroxenes are diopside-hedenbergite solid solutions containing less than 5 mol% johannesenile. Some pyroxenes from a Pb-Zn calcic-magnesia skarn deposit display an increase in Mn content. Only Sn-W calcic skarn deposits and Pb-Zn calcic-magnesia skarn deposits contain garnets with more than 15 mol% (spessartine + almandine + pyrope). Some relationships have been established between the compositions of garnets and pyroxenes and the metallization types of economically important metals in skarn deposits.     

Climate and crop yields in Northern Africa (Senegal,Sudan, Tunisia)

The study attempts to relate crop yields to climatic events in the Sahelian Zone of Africa. The examples are taken from Senegal, Sudan and Tunisia. Theinvestigation was centered to examine closely the relations between weather and crop yields, that means first of all to analyze the influence of the inter-annual variations of the weather on the yields. The aim was to reveal the dependency of the temporal variability of the yields (1960–1980) on the climatic parameters during the different phenological stages of the plants. This analysis made it possible to develop models of prognosis for different cultivated plants (food crops basically). In general suitable models of forecasts could be established for all food crops. An early and exact prediction of harvest losses or surpluses could reduce negative effects for the respective population in unfavourable, and induce food storage in favourable years.     

机载雷达和辐射计数据反演植被覆盖区土壤水分的初步研究

用土壤水分试验(SMEX02)中获取的机载雷达和辐射计(PALS)数据进行反演土壤水分的研究。首先利用PALS数据中雷达和辐射计对土壤水分最敏感的波段,进行主被动结合的多元线性回归反演土壤水分。结果表明,这种方法并不能有效地提高反演精度;然后,改进了一个新提出的适用于大尺度星载C波段辐射计数据的土壤水分获取方法,提高其运算效率,并将该算法应用到PALS数据,一方面验证了该方法在机载高分辨率数据和非C波段下的适用性,另一方面对该方法进行了定量化评价。     

广东百顺地区伽马场参数特征及其与铀矿化关系

运用伽马场参数特征与铀矿化关系,结合判别分析系数和伽马频率曲线形态,对百顺地区的牛澜、烟筒岭、百顺硅化断裂带的异常点、带的找矿远景区段作了评价,简述伽马频率曲线形态与矿体空间位置的关系。     

苏丹Muglad盆地Fula坳陷油气地球化学特征与成藏意义

Fula坳陷位于Muglad盆地东北部,面积约5 000 km2,FN油田是该坳陷最大的亿吨级油田。油气储层主要为白垩系Abu Gabra、Bentiu和Aradeiba组。应用油藏地球化学的方法对FN油田的成藏期次进行了探讨。FN油田Abu Gabra、Bentiu和Aradeiba组原油特征相似,来源于同一套烃源岩,原油既表现出正构烷烃、藿烷、甾烷系列分布完整等正常油特征,又表现出色谱基线抬升、高峰度UCM、25 降藿烷出现等生物降解油特征,这些特征表明FN油田经历了至少两期成藏过程,早期充注的原油遭受生物降解后又接受后期成熟度较高的原油充注。根据构造演化、埋藏史和生排烃史可以研究生烃期次及油气成藏特征。Abu Gabra组烃源岩发生了两次生烃作用,第一次生烃作用发生在晚白垩世,Ro达到0.6%以上,进入生排烃作用阶段,晚白垩世末构造抬升作用使这次生烃产物遭受较为严重的生物降解;第二次生烃作用发生在古近纪,Abu Gabra组烃源岩进入生油高峰阶段,是本区最重要的一次生油作用和成藏过程,与该次成藏事件相关的构造圈闭是Fula坳陷油气勘探的重点。     

Heavy metals concentration in soils under rainfed agro-ecosystems and their relationship with soil properties and management practices

Heavy metals are governed by parent material of soils and influenced by the soil physicochemical properties and soil and crop management practices. This paper evaluates total heavy metal concentrations in rainfed soils under diverse management practices of tropical India. Vertisols (clayey soils with high shrink/swell capacity) had the highest concentrations of heavy metals. However, chromium (Cr) content was above the threshold value in Aridisol [calcium carbonate (CaCO₃)]-containing soils of the arid environments with subsurface horizon development. Concentration increased at lower depths (>30 cm). Basaltic soils showed higher concentrations of nickel (Ni), copper (Cu) and manganese (Mn). Cadmium (Cd), cobalt (Co), Cu and Mn concentrations were higher in soils cultivated to cotton, whereas Cr concentration was above the threshold level of 110 mg kg^?1 in food crop cultivated soils. As the specific soil surface is closely related to clay content and clay type, soil’s ability to retain heavy metals is more closely tied to the specific surface than to the soil cation exchange capacity. Higher positive correlations were found between heavy metal concentrations and clay content [Cd(r = 0.85; p ≤ 0.01); Co (r = 0.88; p ≤ 0.05); Ni (r = 0.87; p ≤ 0.01); Co (r = 0.81; p ≤ 0.05); Zn (r = 0.49; p ≤ 0.01); Cr (r = 0.80; p ≤ 0.05); Mn (r = 0.79; p ≤ 0.01)]. The amounts of nitrogen–phosphorus–potassium applied showed a positive correlation with Co and Ni (r = 0.62; p ≤ 0.05). As several soils used for growing food crops are high in Ni, Cr and Mn, the flow of these metals in soil–plant–livestock/human chain needs further attention.     

哀牢山南段长安金矿床岩浆岩的岩石学特征及其与成矿关系探讨

长安大型金矿床位于哀牢山成矿带南段,矿区内出露煌斑岩、辉长岩、辉绿岩、正长花岗岩、正长花岗斑岩等岩株和岩脉,矿体均与脉岩共生或相互切穿。各类岩浆岩和矿石的地质、岩相学、岩石地球化学的系统研究表明,矿区内岩浆岩可能为同源岩浆演化产物,但煌斑岩、辉绿岩与矿化关系更为密切。金成矿物质具有壳幔混源的特点,成矿流体由岩浆水与地层变质水混合而成。在喜山期,强烈的壳幔相互作用过程导致了区内的岩浆和热液活动,大规模富碱岩浆上侵的热驱使岩浆水循环并与矿区地层在造山作用下脱水产生的富CO2的变质水混合,萃取地层及略早形成的脉岩中的Au等成矿元素,在适宜的物理化学条件下和成矿空间内卸载并富集成矿。     

苏丹哈马迪金矿地球化学特征及成因探讨

苏丹哈马迪金矿区矿石与岩石稀土配分曲线的相似性表明二者具有同源性;矿石硫同位素组成δ(34S)值为较小的负值,表明区内硫来源单一,且硫质应为深源物质;而矿石中的氢、氧同位素特征则表明金矿热液应来源于变质热液.众多事实表明,哈马迪金矿与泛非造山运动及其后的区域变质作用关系密切,成矿热液来源于围岩,属受剪切作用控制的变质热液型金矿床.     

Soil moisture retrieving using hyperspectral data with the application of wavelet analysis

As a powerful tool, the wavelet transform method has been widely used in feature extraction for hyperspectral data, while few studies are focused on soil moisture retrieving. The objective of this study was to evaluate the effectiveness of discrete wavelet transform (DWT) for soil moisture retrieving. In this study, a total of 78 measurements of soil moisture and hyperspectral data were collected through soil sampling as well as laboratory quantitative control. There were 13 different mother wavelets capable of decomposing hyperspectral data that were recommended, along with six decomposition levels from 5 to 10. The performances of two feature extraction methods namely band selection and DWT were compared, using three indexes, i.e., R ², R _adj and root mean square error (RMSE) introduced to validate soil moisture retrieving results. The experimental results indicated that the wavelet transform method could significantly reduce the dimensionality of hyperspectral data, resulting in a much more effective performance. Among the 78 estimation models using the wavelet transform, there were 42 models superior to band selection, with 24 models yielding good correlations between the predicted soil moisture and the measured ones (R ² ≥ 0.7, RMSE ≤ 0.050, p ≤ 0.05). Furthermore, when the wavelet decomposition level was 9 and the mother wavelets were Daubechies 2, Daubechies 4, Reserve Biorthogonal 3.3 and Biorthogonal 6.8, the retrieving results were optimum. Additionally, the experimental results proved that the wavelet analysis technique was capable of preserving high- and low-frequency spectral information at different decomposition scales, and could correctly reflect the variation of soil moisture. Thus, it would be helpful in further environmental monitoring.     

赣南淘锡坝矿床岩浆岩年代学、地球化学特征及其与成矿关系

淘锡坝大型锡矿位于华南武夷山成矿带与南岭成矿带的交接部位,其矿床类型、成因、成岩成矿关系十分复杂,且一直缺乏有效的约束。文章围绕着矿床内发育的岩浆岩开展了系统的岩石学、锆石U-Pb年代学和岩石地球化学研究。淘锡坝矿床岩浆岩具有多阶段多岩相演化特征,从早到晚分别为：凝灰岩→中-粗粒似斑状花岗岩→细粒花岗岩→花岗斑岩。LA-ICP-MS锆石U-Pb年代学研究显示,淘锡坝锡矿具有140~148.4 Ma（中酸性火山岩）和122.3~138 Ma（花岗岩类）2个主成岩期。淘锡坝花岗岩具有高硅、富钾、贫钙的特点,属A型花岗岩,凝灰岩具有高硅、富钙的特点。尽管二者均相对富集不相容元素Rb、Th、U、Nb,亏损Ba、Sr等高场强元素,但其具有不同来源和演化进程,前者主来源于古老地壳物质,并且有明显的幔源物质的加入,经历了斜长石的分离结晶,后者主要来源于古老地壳物质的部分熔融,经历了钾长石的分离结晶。此外,淘锡坝花岗岩成岩年龄与成矿年龄一致,而凝灰岩年龄则显著早于成矿年龄（114~138.2 Ma）,并且花岗岩相对于凝灰岩具有更高的演化程度和更低的氧逸度条件,更加有利于锡的富集。因此,淘锡坝矿床锡矿化应与花岗岩关系更为密切,成矿母岩为中-粗粒似斑状花岗岩与细粒花岗岩,形成于燕山晚期华南大规模陆壳伸展的背景之下。     

利用土中水分蒸发特性和微观孔隙分布规律确定SWCC残余含水率

残余含水率在非饱和土渗流理论、强度理论等方面都是重要的参数,然而土-水特征曲线（SWCC）试验测量时一般难以达到残余阶段,常常通过经验法（包括模型拟合法）估算残余含水率,方法的适用性值得论证。以武汉黏性土为研究对象,制备不同初始孔隙比试样,利用压力板仪测量SWCC,通过模型拟合的方法计算残余含水率;进行自然状态下水分蒸发试验,根据失水速率定义了临残时间,依据临残时间确定残余含水率;利用核磁共振技术研究微观孔隙分布特性,解释控制残余含水率大小的微观规律。研究结果表明：模型拟合的方法可估算残余含水率,但准确性与模型选择及残余含水率初步范围的限定直接相关;水分蒸发试验是确定残余含水率有效可行的直接方法;武汉黏性土微观孔隙呈三峰分布,残余含水率与第1峰之前的微观孔隙水分紧密相关,依据弛豫时间小于0.267 38 ms的T2谱面积可较为准确地预测残余含水率,对于其他土体该方法需要进一步论证与完善。     

Magnetic properties of river sediments and their relationship with heavy metals and organic matter in the urban area in Lanzhou, China

As the largest industrial city locating in the Northwestern China, Lanzhou has become one of the most seriously polluted cities in the world. In this study, investigations were performed on the magnetic properties, heavy metals and organic matter contents of a total of 23 sediment samples collected from eight selected rivers in the Lanzhou urban area. The results of the study indicate that the magnetic properties of the sediment samples are predominated by low-coercivity magnetite. The river sediments are classified into three types, i.e., downstream polluted, upstream polluted, and less affected, based on the contribution from anthropogenic activities in different segments of the river as indicated by the variation of magnetic mineral concentration parameters. Moreover, a strong linear positive correlation exists among some of the magnetic parameters and organic matter content, heavy metals (Cr, Ni, Pb, Zn, Fe) and total enrichment factor (R) of the bulk deposit samples, which indicates that environmental magnetic technology may be an effective method for distinguishing source apportionment and monitoring river sediment pollution in urban areas.     

应力比与含水状态对松散堆积体动力参数及地表反应谱的影响

动剪切模量Gd与阻尼比D是岩土体地震反应分析的两个主要参数,而初始状态是动力参数主要影响因素之一。通过大型动三轴试验,研究了应力比与含水状态对松散堆积体Gd与D的影响。试验结果表明,应力比Kc对松散堆积体最大动剪切模量Gdmax有重要影响,一定范围内（Kc=1～3）,Kc越大,最大动剪切模量Gdmax越大,在Hardin公式基础上发展了一个考虑Kc影响的经验公式。对比松散堆积体饱和与风干两种状态的Gd/Gdmax-?dn（归一化动剪应变）关系曲线,发现风干状态下松散堆积体的Gd/Gdmax-?dn关系表现出更明显的非线性,另外风干状态阻尼比略大于饱和状态。应用改进的Gdmax经验公式与Gd/Gdmax-?dn关系进行了松散堆积体地表的地震反应谱分析,计算结果表明,应力比与含水状态对地表加速度反应谱有重要影响。     

岷江上游河流阶地发育特征及与古滑坡关系初步分析

河流阶地形成演化及其对滑坡的控制是近年来古滑坡研究的热点问题。笔者在对岷江上游河流阶地和古滑坡实地调查测试的基础上,对岷江上游河流阶地的级序、拔河高度、成因类型等进行了分析,绘制了阶地高程位相图和年龄位相图,并结合阶地和古滑坡年代,讨论了阶地与古滑坡的发育关系等。主要取得了以下认识：1）岷江上游的河流阶地具有分段性,成因主要为气候多期次波动与构造活动共同作用,古滑坡及堰塞湖是影响高山峡谷区河流阶地发育的重要因素;2）叠溪-茂县段在20~30 ka B. P.发生了多处大型古滑坡,其中20 ka B. P.的古滑坡可能主要是气候波动引发,30 ka B. P.发生的古滑坡可能主要受控于构造活动（地震）;3）岷江上游大量分布的古滑坡堆积体与阶地发育的叠置关系有待进一步理清,开展该地区的河流阶地级序研究要充分考虑古滑坡和堰塞湖的影响

     

安徽铜陵凤凰山燕山期中酸性侵入岩地球化学特征及其与金属成矿关系

安徽铜陵凤凰山铜矿是铜陵矿集区内最典型的矽卡岩型铜矿床之一,也是凤凰山矿田内规模最大的铜矿床。矿区内新屋里岩体属于高钾钙碱性系列,主要岩性为石英二长闪长岩和花岗闪长岩。岩石地球化学特征表明凤凰山中酸性侵入岩岩浆属于壳幔混合型,原始岩浆来源于上地幔碱性玄武岩区并有地壳物质混染,在岩浆不断演化过程中有外来物质的加入,成岩过程以混合作用为主。凤凰山铜矿体分布于岩体与大理岩的内矽卡岩带上,岩体中铜含量较高。铜矿体是岩浆期后热液交代碳酸盐地层形成的。矿体的空间分布受构造变形-岩浆侵入高温高压作用的双重控制。矿化经历了从高温矽卡岩阶段到中低温热液阶段的多期次复合成矿作用。