A regional tree ring-width index chronology prepared from various tree core samples of the western Himalaya has been analyzed in relation to climate fluctuations. The correlation analysis of tree ...ring chronology shows significant positive correlations with regional rainfall and standardized precipitation evapotranspiration index (SPEI) and negative correlations with temperature and vapor pressure (VP) during the spring season. The correlation coefficients (CCs) of tree ring-width index chronology with rainfall, temperature, SPEI, and VP during 1901–1990 are 0.50, −0.49, 0.65, and −0.51, respectively. All CCs are significant at 0.1% level. The highly significant CCs between tree ring-width index chronology and SPEI indicate that tree growth over the western Himalaya is more sensitive to soil moisture availability than rainfall, whereas the rising VP is found to have a significant moisture stress condition to tree growth by accelerating the evapotranspiration, which is not conducive for the development of tree growth in the region. So, based on the strong association between tree ring-width index chronology and SPEI; the reconstructions of SPEI and VP are developed back to AD 1861, that show the long period of dryness during 1936–1963.
Following the June 2013 disaster in the Uttarakhand Himalayas, many discussions are ongoing with regard to how climate change is seeking revenge on mankind by endowing us with disasters! The event ...was mostly linked with the occurrence of an extreme event due to climate change. In view of this, an attempt has been made in this paper to analyse the extreme rainfall events experienced by the Uttarakhand during 1901-2013 using more than 100 stations' daily rainfall data. The study revealed that during the 113-year period, the highest numbers of extreme events were recorded during the decade 1961-1970, and to some extent in the decade 1981-1990. Thereafter, there is a decrease in extreme rainfall events. The comparative study of extreme events prior to 1901 showed that on 17-18 September 1880, a rainstorm which occurred in close vicinity to Uttarakhand caused serious floods and damage to lives and properties. The extreme rainfall recorded by some stations during this unprecedented rainstorm has not been surpassed to date.
There are limitations in using monthly rainfall totals in studies of rainfall climatology as well as in hydrological and agricultural investigations. Variations in rainfall may be considered to ...result from frequency changes in the daily rainfall of the respective regime. In the present study, daily rainfall data of the stations inside the Koyna catchment has been analysed for the period of 1961–2005 to understand the relationship between the rain and rainy days, mean daily intensity (MDI) and seasonal rainfall over the catchment on monthly as well as seasonal scale. Considering the topographical location of the catchment, analysis of seasonal rainfall data of 8 stations suggests that a linear relationship fits better than the logarithmic relationship in the case of seasonal rainfall versus mean daily intensity. So far as seasonal rainfall versus number of rainy days is considered, the logarithmic relationship is found to be better.
Currently there is much discussion regarding the impact of climate change and the vagaries of the weather, in particular extreme weather events. The Himalayas form the main natural water resource of ...the major river systems of the Indian region. We present a brief review of the available information and data for extreme rainfall events that were experienced in different sectors of the Himalayas during the last 137 years (1871–2007). Across the entire Himalayas, from east to west, there are now 822 rainfall stations. There was an increase in the rainfall station network from 1947 onwards, especially in the Nepal and Bhutan Himalayas. Extreme one-day rainfall has been picked out for each station irrespective of the period for which data are available. The decadal distribution of these extreme one-day rainfalls shows that there is a considerable increase in the frequencies during the decades 1951–1960 to 1991–2000, whereas there is a sudden decrease in the frequencies in the present decade during 2001–2007, indicating the need to understand the response of the systems to global change and the associated physical and climatological changes. This is essential in terms of preserving this natural resource and to encourage environmental management and sustainable development of mountain regions.Citation Nandargi, S. & Dhar, O. N. (2011) Extreme rainfall events over the Himalayas between 1871 and 2007. Hydrol. Sci. J.56(6), 930–945.
A significant part of northern India is covered by the Himalayas, where a number of major Indian rivers originate. In the present study, a detailed analysis of rainstorms that affected the northwest ...region of the Himalayas has been made to assess the orographic effect of the Himalayas on precipitation in this region during the 135 years from 1875 to 2010. The study showed that the northwest Himalayas have experienced five most-severe rainstorms whose rain depths have not been surpassed so far. These severe rainstorms caused heavy to very heavy rainfall over the region that led to tremendous destruction to crops, communications, and livestock. Severe rainstorms have not occurred during the 2001–10 decade. It is also noticed that severe floods in this region have not occurred because of a “break monsoon situation” in the middle or eastern Himalayas.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Estimation of design storm rain depths of probable maximum precipitation (PMP) magnitudes over different zones of the Krishna basin, India, was attempted by using daily rainfall data of about 570 ...raingauge stations in and around the basin for a 102-year period (1901-2002). By considering the geographical location, orographic features and rainfall characteristics, the entire basin was divided into nine zones. Analysis of severe rainstorms over each zone was carried out and envelope rain depths (standard project storm, SPS, rain depths) over each zone were estimated. These SPS rain depths were then adjusted with moisture maximization factors (MMFs) of respective severe rainstorms to work out the PMP design rain depths. On the basis of available hourly data, average time distribution was also calculated. The study was carried out with the aim of estimating the requisite standard projects storms and probable maximum storms or PMP depths to derive the corresponding design flood estimates. This may serve as a convenient tool for design engineers, in the estimation of design storm rain depths for different sub-basins and the entire Krishna basin while constructing any hydraulic structure connected with irrigation, hydropower generation and flood control in the homogeneous region of the basin.
Citation Kulkarni, B. D., Nandargi, S. & Mulye, S. S. (2010) Zonal estimation of probable maximum precipitation rain depths over the Krishna basin in peninsular India. Hydrol. Sci. J. 55(1), 93-103.
The analysis of rainstorms is of prime importance for the planning and design of water resources of any region. In the absence of actual records of streamflow data, analysis of rainstorms is useful ...for assessing flood potentialities as well as the runoff of river catchments. This study provides pertinent information on the spatial distribution characteristics of severe rainstorm events that occurred over the Godavari and its subbasins on the basis of 110 yr (1891–2000) of available rainfall data. The analysis showed that the August 1986 rainstormhad its areal extension over more than a 150 000 km² area. It is also seen that the August 1913 rainstorm was the most efficient rainstorm over the basin. The rain depth data of severe rainstorms given in this paper can provide a reliable set of information to assess water resource planning on a probability basis. The relationship between the point to areal rainfall and area of the rainstorms from 1- to 3-day durations is also determined.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Tree-ring chronologies from different sites of western Himalaya have been used in this study to examine the climate variability/change over the region. The 1st principal component (PC1) which has ...been computed by multi species tree ring chronologies of western Himalaya is negatively correlated with heat index (HT), temperature (TM) and potential evapotranspiration (PET) but positively with the rainfall of the region during spring season. However, HT and PET showed the stronger influence on tree growth than temperature which has been used to reconstruct the spring season PET back to A.D. 1779. The extended periods of low PET have been found at ending phase of Little Ice Age (LIA) during 1827–1845. The reconstructed PET showed that the advance of the glaciers over the western Himalaya might have influence on reduction of downward shortwave radiation on the earth's surface; which may in turn cause low temperature and low PET over the region. The result indicates that longer tree ring chronologies from the western Himalaya are very useful to get valuable information on PET and glacier fluctuation during the last few centuries. The highest PET in the entire reconstruction was noticed during the year 1921 in the 20th century, which has been associated with lowest trees growth in the entire western Himalaya.
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