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91.
A. M. A. Ismail 《GeoJournal》1991,23(3):233-237
This study is mainly about the relationship of the moisture holding and release capacity of soils with their texture, particularly the clay fraction. Soil samples collected from various sites in the Sudan Gezira were analysed for physical and chemical properties and moisture characteristics. Generally the soils were clayey except the recent alluvium which was loamy. The pH was alkaline and the electric conductivity < 1.0 dS m–1. The studied soils were calcareous and very poor in organic matter, their intermediate to high water holding capacity being due mainly to the presence of large quantities of clay. Matric potentials of –0.4 to –1.5 MPa reduced soil moisture for all types of soils but the effects were not necessarily quantitatively equal. Permanent wilting point — moisture content at – 1.5 MPa — varied widely (10.5 – 22.0%) amongst the different soils and this was mainly attributed to texture and mineralogy of the soil clays. Bulk density decreased with increase in clay content. Calcium carbonate content was found to have no apparent relationship with the moisture content of these soils. The amount of silt fraction seems to have an overriding effect on the relationship between soil moisture availability in the recent alluvium soil and its subsequent release to growing plants. The results are discussed in relation to the phenomenon of mid-day stress observed in all grown crops of the Sudan Gezira.  相似文献   
92.
The correlation function theory on the basis of prescribed boundary conditions provides a deeper understanding in studying the dynamical parameters of galaxy clusters. The approach approximates that the moderate dense systems discussed by a two point correlation function is helpful for describing the dynamical nature of galaxy clusters. The projected theory of two point correlation function for point mass and extended mass structures can be used an alternative tool in measuring the average peculiar motion and temperature profile of galaxy clusters.  相似文献   
93.
We propose that bubbles of matter ejected from magnetic reconnection sites in polar plumes drive the solar wind in coronal holes.  相似文献   
94.
95.
Dera Ismail Khan (DIK) is situated in the Lower Indus Basin of Pakistan. The land use has been changed in the canal command area due to irrigation activities near the Indus River. To check the current status and predict the groundwater levels in the area, the unconfined aquifer has been simulated in Visual MODFLOW for a period of 35 years, i.e., from 1985 to 2020. The 2900-km2 area has been modeled with a grid of 500 by 500 m and the depth set to 100 m. The aquifer in the study area has been divided vertically and laterally into three and ten zones, respectively, for the characterization. Water wells and streams were used as the sinks and hydrologic boundaries, respectively. The model was successfully calibrated in steady and the non-steady state. The simulation revealed that the whole simulation can be divided into two phases, i.e., before and after the construction of the Chashma Right Bank Canal (CRBC), whereas the results were summarized in the form of water table depth maps and groundwater budget calculations. To determine the groundwater sustainability, a conjunctive use scenario has been employed to simulate the aquifer dynamics till 2020. The simulation revealed incremental drawdowns till the end.  相似文献   
96.
97.
Climatic data from four meteorological stations in Iraq (Mosul, Baghdad, Basra, and Rutba) were obtained. The recorded temperature data since 1960 till 2007 and rainfall and evaporation data since 1960 till 2008 and 1970 till 2008, respectively, were used and interpreted. This study showed an increase in temperature of about 5°C/47?years and an increase in evaporation rate with a decrease in the rainfall rate. Carbon dioxide in the atmosphere appears to be a factor controlling climate change. Basra climate, due to its location which is nearest to the Arabian Gulf, is expressed as a coastal climate and has a different behavior from Mosul, Baghdad, and Rutba, which are considered as terrestrial climates.  相似文献   
98.
By definition, a crisis is a situation that requires assistance to be managed. Hence, response to a crisis involves the merging of local and non-local emergency response personnel. In this situation, it is critical that each participant: (1) know the roles and responsibilities of each of the other participants; (2) know the capabilities of each of the participants; and (3) have a common basis for action. For many types of natural disasters, this entails having a common operational picture of the unfolding events, including detailed information on the weather, both current and forecasted, that may impact on either the emergency itself or on response activities. The Consequences Assessment Tool Set (CATS) is a comprehensive package of hazard prediction models and casualty and damage assessment tools that provides a linkage between a modeled or observed effect and the attendant consequences for populations, infrastructure, and resources, and, hence, provides the common operational picture for emergency response. The Operational Multiscale Environment model with Grid Adaptivity (OMEGA) is an atmospheric simulation system that links the latest methods in computational fluid dynamics and high-resolution gridding technologies with numerical weather prediction to provide specific weather analysis and forecast capability that can be merged into the geographic information system framework of CATS. This paper documents the problem of emergency response as an end-to-end system and presents the integrated CATS–OMEGA system as a prototype of such a system that has been used successfully in a number of different situations.  相似文献   
99.
I-DtjcrONAlpine environment enjoys a distinct set of physicochemical conditions asl compared to other aqueous systems. Thehydrochemical characteristics of meltwater draining from thisenvironment are different from the other aqueous ecosystemsdue to their mountainous nature and extreme cold climatic conditions. The high concentration of various chemical constitu.ents in meltwater shows the intensive chemical weathering inthe basin. The rapid physical weathering due tO grinding actionof the gl…  相似文献   
100.
In the agricultural industry, biomass waste generated along with the production of food, is transformed into value-added products. Also, the demand for the slow or control release fertilizer is increasing to reduce the cost of maintaining the agricultural land. These issues are tackled by converting biomass waste to a slow fertilizer release vehicle and biodegradable water retention material that could reduce the cost for fertilizer application and simultaneously preserved the soil from dryness. A series of carboxymethyl sago pulp (CMSP) hydrogels were prepared by electron beam irradiation. Slow release systems were evaluated by loading potassium nitrate (KNO3) and ammonium nitrate (NH4NO3) into the CMSP hydrogels. These CMSP hydrogels endow slow release property, biodegradability and a soil moisture preservation property that could find greener application in agricultural industries. The results indicate that CMSP hydrogels have a great potential as an agent for slow release of fertilizers.  相似文献   
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