气候变化对喜马拉雅中部甘达基河流域濒危物种的影响预测（英文）

甘达基河流域位于喜马拉雅山脉中部,是众多濒危野生物种的重要栖息地。然而气候变化使该流域的生态环境变得愈发脆弱。本研究利用最大熵物种分布模型(Max Ent)评估气候变化对喜马拉雅黑熊(Ursus thibetanus laniger)和印度花豹(Panthera pardus fusca)等濒危物种空间分布变化的潜在影响。研究基于物种出没地点、生物气候和地形(海拔、坡度和坡向)等数据拟合模拟并预测物种在目前与未来的潜在分布情况。研究结果显示,目前喜马拉雅黑熊的高度适宜区面积约为1642 km²,占流域面积的5.01%,预计至2050年,其高度适宜区面积在甘达基河流域内将会增加约51 km²;印度花豹的高度适宜区面积约为3999 km²,占流域面积的12.19%,预计至2050年可能会增加到4806 km²。喜马拉雅黑熊的栖息地面积可能会在研究区域的东部(伯塞里、塔托潘尼和班塞以北)增加,而在东部(颂当、切坎帕)、西部(布尔提邦和波邦)和北部(桑波切、玛南、切坎帕)减少;印度花豹的栖息地面积则将在研究...     

Lacustrine Record of 1954 Flood Event on Begnas and Rupa Lake,Central Nepal

In recent decades, there have been discussions and predictions regarding the impact of climate on floods, due to its socioeconomic and environmental consequences. For accurate prediction of future flood events and their impacts, it is crucial to have an improved understanding on past flood events. Lacustrine sediments have been used as a natural archive to study the past flood events. Here, we study the impact of 1954 flood event on the lacustrine environment of Bengas and Rupa Lake in central Nepal based on X-ray fluorescence spectrometry (XRF) element analysis, magnetic susceptibility (MS), total organic carbon (TOC) and the biomarker molecular compositions. Results showed that 1954 flood event had significant impacts on the two lakes in terms of detrital input, organic matter deposition and aquatic production. Before the flood event, both two studied lakes had relatively lower catchment erosion rate, lower organic matter deposition and aquatic production. During the flood event, catchment erosion and aquatic production increased in both lakes due to mass transport deposits and the increased nutrition loading attributed to flood event. Following the flood event, Begnas Lake showed the sharp increase in organic matter deposition, whereas in the Rupa Lake organic matter deposition showed minor changes. The difference in organic matter deposition in lakes during flooding event is likely due to detrital material brought and deposited by the flood activity. Overall our results suggest that lacustrine sediments are sensitive to the extreme event and would be an ideal archive for the reconstruction of flood events.     

Evaluation of regional fracture properties for groundwater development using hydrolithostructural domain approach in variably fractured hard rocks of Purulia district,West Bengal,India

Estimation of geohydrologic properties of fractured aquifers in hard crystalline and/or metamorphosed country rocks is a challenge due to the complex nature of secondary porosity that is caused by differential fracturing. Hydrologic potentiality of such aquifers may be assessed if the geological controls governing the spatial distribution of these fracture systems are computed using a software-based model. As an exemplar, the Precambrian metamorphics exposed in and around the Balarampur town of Purulia district, West Bengal (India) were studied to find out the spatial pattern and consistency of such fracture systems. Surfer and Statistica softwares were used to characterize these rock masses in terms of hydrological, structural and lithological domains. The technique is based on the use of hydraulically significant fracture properties to generate representative modal and coefficient of variance (Cν) of fracture datasets of each domain. The Cν is interpreted to obtain the spatial variability of hydraulically significant fracture properties that, in turn, define and identify the corresponding hydrolithostructural domains. The groundwater flow estimated from such a technique is verified with the routine hydrological studies to validate the procedure. It is suggested that the hydrolithostructural domain approach is a useful alternative for evaluation of fracture properties and aquifer potentiality, and development of a regional groundwater model thereof.     

Multi-model ensemble schemes for predicting northeast monsoon rainfall over peninsular India

The northeast (NE) monsoon season (October, November and December) is the major period of rainfall activity over south peninsular India. This study is mainly focused on the prediction of northeast monsoon rainfall using lead-1 products (forecasts for the season issued in beginning of September) of seven general circulation models (GCMs). An examination of the performances of these GCMs during hindcast runs (1982–2008) indicates that these models are not able to simulate the observed interannual variability of rainfall. Inaccurate response of the models to sea surface temperatures may be one of the probable reasons for the poor performance of these models to predict seasonal mean rainfall anomalies over the study domain. An attempt has been made to improve the accuracy of predicted rainfall using three different multi-model ensemble (MME) schemes, viz., simple arithmetic mean of models (EM), principal component regression (PCR) and singular value decomposition based multiple linear regressions (SVD). It is found out that among these three schemes, SVD based MME has more skill than other MME schemes as well as member models.     

Heavy Mineral Placer Deposits of Ekakula Beach, Gahiramatha Coast, Orissa, India

Abstract: Ilmenite, hematite, garnet, monazite, zircon, rutile, magnetite, sillimanite, pyroxene and amphibole from the beach sands of Ekakula, Gahiramatha coast, Orissa, India are reported here for the first time. Their total concentration varies from 26. 4 to 100%. Ilmenite, monazite and zircon are between 100 and 300 um in size and are well rounded in shape. Ilmenite-hematite intergrowth is common. Ilmenite has 50. 02–54. 73% TiO₂, 42. 42–46. 90% FeO (total Fe) and small amounts of Al, Mn, Mg, Ca, Ba, Si, V, Cr, and Zn. The bulk samples contain 10. 63–41. 42 % TiO₂, 6. 15–26. 07 % FeO, 5. 86–16. 75 % Fe₂O₃, 7. 41–61. 74 % SiO₂, 1. 39–12. 83% A1₂O₃, 0. 32–4. 97% CaO, 0. 53–4. 24% P₂O₅, 0. 17–3. 27% MgO, 0. 15–2. 97% Na₂O, 0. 07–2. 34% K₂O, and 0. 05–0. 71% V₂O₅ together with appreciable amounts of La, Ce, Pr, Nd, Sm, Eu, Y, U, Th, Zr, and trace amounts of Pb, Zn, Cu, Ni, Co, and Cr. Khondalite, charnockite, calc-silicate granulite, leptynite, migmatite, gneiss, basic granulite and pegmatite of the Eastern Ghats appear to be the major source for the above heavy mineral assemblages. The samples are amenable to gravity and magnetic methods of beneficiation.     

基于遥感影像的甘达基流域博卡拉和巴拉普尔的土地利用变化及其驱动力研究（英文）

城市扩张是反映经济增长的重要指标,但随意的城市扩张也带来了严重的社会经济问题、环境问题以及城市土地管理问题。在这个背景下,理解城市扩张的过程对于指导城市的可持续增长具有重要意义。本研究采用基于遥感影像的监督分类方法,分析了甘达基流域内的两个大城市—博卡拉和巴拉普尔1990–2018年的城市用地变化。结果表明:在过去的28年,博卡拉和巴拉普尔的城市面积分别显著扩张了300%和近500%。人口增长、城市基础设施和便利的生活方式引起周边地区向城市的人口迁移,是造成本研究区城市扩张的主要原因。除此之外,不断变化的城市定义和城市边界的扩张是造成城市快速扩张的关键因素。由于上述两个城市拥有高水平的商业活动以及现代化的设施,未来城市规模可能继续扩大。应当通过城市规划和政策减少随意的城市扩张,从而实现城市的可持续发展。