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Natural Hazards - Time series studies depend mostly on stochastic models for radon seasonal, annual or temporal variability explanations. Others solve radon transport steady state equation... 相似文献
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A Conceptual Framework for Enhancing the Utility of Rainfall Hazard Forecasts for Agriculture in Marginal Environments 总被引:1,自引:0,他引:1
Muhammad?T.?UsmanEmail author Emma?Archer Peter?Johnston Mark?Tadross 《Natural Hazards》2005,34(1):111-129
Semi-arid and dry sub-humid areas (especially in the tropics) are characterized by high inter-annual and intra-seasonal rainfall variability. Agriculture, which employs the bulk of the rapidly increasing populations, is largely rain-fed, low-input based and highly resource dependent. Recent spates of drought have, therefore, exacerbated the now-too-familiar specter of famine and starvation in these areas with glaring examples being the recurring episodes in sub-Saharan Africa since the great Sahel drought of 1969–1973. A great need for accurate and timely hazard forecast products in aid of agriculture thus exists.Several schemes are currently employed by various agencies around the globe in this direction. There does remain, however, a gap between product provision and user expectations. This paper examines this gap suggesting a five-point framework within which it can be addressed as an action agenda for the climate science community. The paper posits that changes are possible to existing methodologies (related to three of these points), which, within the context of current science, can greatly enhance the utility of forecast products for agriculture in marginal areas. The remaining two points have, however, been identified as requiring additional applied research and necessary pointers for addressing these issues are provided. First is the need for appropriate impact-related indicators for intra-seasonal and interannual rainfall variability that are easy to compute, amenable to forecasting and follow closely the experiences of farmers in marginal areas. The second is a consideration of appropriate forecast information formatting and communication medium that guarantee effective feedback between forecast producers and users. Specific examples of the status quo and of work currently underway are cited from southern Africa – a region currently attracting international attention as a result of recent droughts and the threat of famine. 相似文献
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In NW Himalayas, the suture zone between the collided Indian and the Karakoram plates is occupied by crust of the Cretaceous Kohistan Island\|Arc Terrane [1] . Late Cretaceous (about 90Ma) accretion with the southern margin of the Karakoram Plate at the site of the Shyok Suture Zone turned Kohistan to become an Andean\|type margin. The Neotethys was completely subducted at the southern margin of Kohistan by Early Tertiary, leading to collision between Kohistan and continental crust of the Indian plate at the site of the Main mantle thrust.More than 80% of the Kohistan terrane comprises plutonic rocks of (1) ultramafic to gabbroic composition forming the basal crust of the intra\|oceanic stage of the island arc, and (2) tonalite\|granodiorite\|granite composition belong to the Kohistan Batholith occupying much of the intermediate to shallow crust of the terrane mostly intruded in the Andean\|type margin stage [2] . Both these stages of subduction\|related magmatism were associated with volcanic and sedimentary rocks formed in Late Cretaceous and Early Tertiary basins. This study addresses tectonic configuration of Early Tertiary Drosh basin exposed in NW parts of the Kohistan terrane, immediately to the south of the Shyok Suture Zone. 相似文献
165.
A joint analysis of river runoff and meteorological forcing in the Karakoram,upper Indus Basin
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Satellite‐geodetic altimetry investigations in the Karakoram have indicated slight mass gain or loss of the glaciers during the early part of 21st century. Equivalent discharge in the upper Indus Basin due to these mass changes has been estimated at 5 to 10% of mean annual flow. However, satellite altimetry and geodetic glacier mass estimates in the extreme topography of the Karakoram have not yet been counter‐validated by hydrological analysis. Therefore, we present a first cross validation of three to five decades of river flow data from the three major watersheds in the Karakoram, with matching series of monthly precipitation, temperature, and evaporation provided by six atmospheric reanalysis products for 1979–2014. The analyses suggest that in most cases river flows have been increasing steadily from the end of the 1960s and 1970s to the middle of the 1990s and have stabilized or are in decline since then. Hunza watershed in Karakoram West shows consistently declining flows over the first half of the analysis period and stable flows during the second half for most of the summer melting season, suggesting mass accumulation. Rising river flows in the Shyok and Shigar watersheds, followed by stabilizing or slightly declining flows from 1995 onward, can be explained by consistently increasing precipitation during the first half of the analysis period, and successive stabilization or minor decline thereof. Flow data do not necessarily suggest considerable loss or gain of glacial mass in the Karakoram during the late 90s and early 2000s as suggested by satellite‐based altimetry studies. 相似文献
166.
Upendra Baral Ding Lin Tapos Kumar Goswami Mondip Sarma Muhammad Qasim Devojit Bezbaruah 《地学学报》2019,31(1):18-27
Geochronology is useful for understanding provenance, and while it has been applied to the central and western Himalaya, very little data are available in the eastern Himalaya. This study presents detrital zircon U–Pb ages from the late Palaeocene–Eocene Yinkiong Group in NE India. The samples are from the late Palaeocene to early Eocene Lower Yinkiong Formation, and the Upper Yinkiong Formation deposited during the early to mid‐Eocene within the Himalayan foreland basin. The U–Pb ages of the detrital zircon within the Lower Yinkiong Formation are older than late Palaeozoic, with a cratonic and early Himalayan Thrust Belt affinity, whereas the Cenozoic grains in the Upper Yinkiong Formation indicate a Himalayan Thrust Belt source and possibly a granitic body within the Asian plate. The shift of the sources and the changes in the foreland basin system strongly suggest that the India–Asia collision in the Eastern Himalaya began before or immediately after the deposition of the Upper Yinkiong Formation, i.e., within the early Eocene (c. 56 to 50 Ma). 相似文献
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Ishtiaq?A.?K.?JadoonEmail author Matthias?Hinderer Beenish?Wazir Rizwan?Yousaf Sher?Bahadar Muhammad?Hassan Zeeshan-ul-Hassan?Abbasi Sidra?Jadoon 《Arabian Journal of Geosciences》2015,8(7):5111-5125
The Salt Range/Potwar Plateau (SRPP) is part of the Himalayan foreland and an important petroleum province in north Pakistan. The hydrocarbons are commonly produced from stacked Cambrian to Eocene clastic and carbonate reservoirs which have an average thickness of 1 km. These strata are overlain by at least 5 km of Miocene and younger continental molasse sedimentation in the deepest part of the foreland basin. Surface and subsurface (seismic interpretations and borehole data) geology combined with the timing and the patterns of sedimentation has allowed to interpret the deformation as thin skinned, with a detachment in weak Eocambrian evaporates and the development of ramp-and-flat structures, since about 8 Ma. We have reviewed the structural interpretations with new borehole logs, field geology, and reserve estimates in this paper to precisely define oil-field structures with a view on future exploration. As a result of this work, 12 oil fields are classified as three detachment folds, four fault-propagation folds, four pop-ups, and one triangle zone structure. The latter two are identified as better prospects with the last one as the best with estimated reserves of 51 million barrels of oil (MMBO). Hence, the triangle zones along with other ramp-and-flat structures from the North Potwar Deformed Zone (NPDZ) are recognized to provide potential future prospects. Finally, a 40-km-long structural cross section from NPDZ is used to discuss complex deformation of the triangle zone and duplex structures as future potential prospects. About 55 km of shortening across the NPDZ during Plio-Pleistocene time is calculated, which has important bearing on the geometry of prospects, reserve calculations, and the future exploration. 相似文献
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