Assessment of Estimated Bedrock and Stream Sediment Geochemical Backgrounds in Catchment Basin Analysis

Natural Resources Research - The weighted mean and the multiple regression techniques are two methods that are employed to estimate elemental background concentration of lithologies upstream of...     

Geospatial modeling for assessing the nutrient load of a Himalayan lake

This research makes use of the remote sensing, simulation modeling and field observations to assess the non-point source pollution load of a Himalayan lake from its catchment. The lake catchment, spread over an area of about 11 km², is covered by different land cover types including wasteland (36%), rocky outcrops (30%), agriculture (12%), plantation (12.2%), horticulture (6.2%) and built-up (3.1%) The GIS-based distributed modeling approach employed relied on the use of geospatial data sets for simulating runoff, sediment, and nutrient (N and P) loadings from a watershed, given variable-size source areas, on a continuous basis using daily time steps for weather data and water balance calculations. The model simulations showed that the highest amount of nutrient loadings are observed during wet season in the month of March (905.65 kg of dissolved N, 10 kg of dissolved P, 10,386.81 kg of total N and 2,381.89 kg of total P). During the wet season, the runoff being the highest, almost all the excess soil nutrients that are trapped in the soil are easily flushed out and thus contribute to higher nutrient loading into the lake during this time period. The 11-year simulations (1994–2004) showed that the main source areas of nutrient pollution are agriculture lands and wastelands. On an average basis, the source areas generated about 3,969.66 kg/year of total nitrogen and 817.25 kg/year of total phosphorous. Nash–Sutcliffe coefficients of correlation between the daily observed and predicted nutrient load ranged in value from 0.80 to 0.91 for both nitrogen and phosphorus.     

Gravitational potential energy of a pair of overlapping galaxies

The interaction of the gravitational potential energy of a pair of overlapping Plummer-model galaxies is determined exactly for various separationsr of their centres. It is shown that the results can be well represented by the simple relationW(r)=–GM ₁ M ₂/(r ²+ ²)^1/2, where 1/ is the average reciprocal distance between the stars of two galaxies of massesM ₁ andM ₂ when they have zero separation.     

Disaster risk management in agriculture: tragedies of the smallholders

Agriculture sector is exposed to a variety of risks and uncertainties which can lead to sizeable losses in crop yields and alter farm incomes. Risk management is, therefore, an essential element of the overall farm management process. Farmers have number of options in managing farm risks; however, smallholders, due to their small operations and limited financial capabilities, find it difficult to adopt sophisticated risk management strategies to overcome yield and income instabilities at farm level. This study is, therefore, designed to investigate the enabling environment for small farmers to manage climatic risks at farm level. A total of 330 sampled respondents from Khyber Pakhtunkhwa Province of Pakistan are randomly selected for the study using multistage sampling technique. Analysis of variance technique is employed to compare the risk management adoption decision of small, medium and large farmers. A post hoc analysis is also performed to highlight the difference in means and the magnitude of differences. The results indicate that smallholders have significantly lower access to credit (both formal and informal), formal information sources along with significantly higher perceptions of pest and diseases. Smallholders are also at the tail end in the adoption of precautionary savings and agricultural credit to manage climatic risk at farm level. The study urges for risk management policies particularly in favor of the small farmers and intervention in the existing information and credit provision programs to facilitate smallholders in managing farm risks.     

Three-Dimensional Wideband Beamforming for Imaging Through a Single Wall

Through-the-wall imaging and urban sensing is an emerging area of research and development. The incorporation of the effects of signal propagation through wall material in producing an indoor image is important for reliable through-the-wall mission operations. We have previously analyzed wall effects, such as refraction and change in propagation speed, and designed a wideband beamformer for 2D imaging using line arrays. In this letter, we extend the analysis to 3D imaging via delay-and-sum beamforming in the presence of a single uniform wall. The third dimension provides valuable information on target heights that can be used for enhancing target discrimination/identification. Supporting simulation results are provided.