Analysis of rainfall and temperature trends in northeast India (original) (raw)
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Journal of Water and Climate Change
Impacts of climate change may vary from location to location for various reasons and may exhibit unique features in some regions. In this study, we considered India's Northeast which is geographically and hydro-meteorologically unique. The Gomati River catchment is the largest and one of the important river catchments in Tripura, a state in the northeastern region of India. Due to changes in climatic conditions over the previous few decades, the flow pattern of this catchment has changed significantly. The study examines the effect of climate change on the climatology of precipitation and streamflow using the simulation output from the Earth System Model (ESM) from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) into two different conceptual hydrological models for streamflow simulation. Findings indicate that water availability is projected to be reduced in the future due to a reduction in the average streamflow volume by approximately 12–30% (varies from m...
Springer Nature Switzerland, 2022
The present study aims to assess the impact of temperature-rainfall (TR) and land use/land cover (LULC) on the hydrological regime of a forested watershed. The authors consulted meteorological, hydrological, and remote sensing data in this research work. The study applied statistical techniques like regression and analysis of variation (ANOVA), which have been used to analyze the variability of TR and LULC and their impact on the hydrological regime of the river. To analyze the variability, the whole study period (1986-2016) was divided into two phases, i.e., 1986-2000 (Phase I) and 2001-2016 (Phase II). The statistical analyses proved that within the study period, water discharge, water level, hydraulic radius, and flow velocity experienced variation significantly (p value < 0.05) except for wetted perimeter (p value > 0.05). All the variables have decreased considerably in the second phase of the study period, i.e., in the 2001-2016 periods. Moreover, phase-wise seasonal analysis proved that the variations during monsoon and non-monsoon are lacking and prominent, respectively. The response of hydraulic variables to temperature-rainfall proved that the hydraulic variables had an insignificant correlation (R = 0.15 to 0.41) with the annual and the monsoon rainfall, while significant relation (R = − 0.26 to 0.78) was observed with the non-monsoon rainfall and temperature (maximum and minimum). There was a significant variation (p value 0.00) of LULC change in both phases. Statistical analyses proved that among the two phases of the study, the mean value of the forest class decreased significantly (from 550.37 to 425.67 km 2). In contrast, rubber plantations increased extensively (from 21.36 to 128.36 km 2) in comparison to the other LULC classes. Statistical analysis proved that the LULC change is very much responsible for the hydrological modifications rather than the rainfall.
River Basin Management - Under a Changing Climate [Working Title]
Due to climate change phenomenon and substantial decrease in water resources, analyzing the streamflow trend is of significant importance. In the present study, investigation was carried out to find rainfall and streamflow trends in the Kosi river watershed at different timescales from 1986 to 2016. Kosi river is one of the principal rivers in the Kumaon region. The different methods employed for trend detection of streamflow and rainfall were the Mann–Kendall (MK) test and the Sen’s slope (SS) estimator. Results showed a statistically significant decreasing trend in pre-monsoonal and annual rainfall with a Sen’s slope of -2.27 and -1.49 mm/year, respectively. The decreasing trends in pre-monsoon, post-monsoon, and winter streamflow were found during 1986–2016, which were not statistically significant. The results of the study help in understanding the variation and availability of rainfall and streamflow in different seasons of the year and motivate to adopt effective water managem...
2021
The present study provides a synoptic view of recent changes in the patterns of rainfall and their linkages to extreme floods in Bhagirathi-Hooghly Basin (BHB). The objectives are: (a) to obtain a better understanding of long-term and short-term trends and variations in rainfall; and (b) to ascertain whether the extreme floods were coincided with multi-decade excess monsoon rainfall epochs at the basin level. To fulfill the above objectives, we use district-wise long-term (1901-2000) monthly rainfall data and annual maximum flood series in BHB. The data are mostly obtained from Indian Meteorological Department (IMD), Irrigation and Waterways Department, Government of West Bengal, numerous research articles, published and unpublished reports. The methodology includes various statistical approaches and simple techniques, such as the Mann-Kendall (MK) test with Sen's slope estimator, Cramer's t-statistic and linear regression in order to evaluate the trends and patterns of the rainfall series. The analyses revealed a long-term insignificant declining trend of annual as well as pre-monsoon rainfall, whereas increasing trend in monsoon and post-monsoon season over BHB. Rainfall during winter seasons showed a decreasing trend. Statistically monsoon rainfall can be considered as very dependable as the coefficient of variation is 17.31%. However, there is decreasing monthly rainfall trend in June and August, whereas increasing trend in July and September. On the other hand, the shorter period of recent data showing higher significance may have better practical utility and correlatable with major floods in the basin. This changing rainfall trends during monsoon months is a major concern for the rain-fed agriculture. The results of this study therefore would be of immense help to the reservoir managers and policymakers in planning and management of water resources of the BHB.
Natural Hazards, 2020
Climate variability and human activities are two major drivers influencing changes in streamflow response of a watershed, and thus assessing their relative effect is essential for developing sustainable water resources planning and management strategies at watershed-scale. In this study, a runoff model driven by rainfall and potential evapotranspiration was established to estimate the effect of climate variability on the changes in annual streamflow of Agula watershed in northern Ethiopia. Significant decreasing trends were observed for annual and wet season streamflow between 1992 and 2012, while dry season streamflow showed an increasing trend. Analyses of seasonal and annual rainfall records showed no significant trends. The change-point test revealed that an abrupt change in annual streamflow occurred in 2000. In the period 2000-2012, the mean annual and wet season streamflow decreased by 36 and 49%, respectively compared with 1992-1999, while dry season streamflow increased by 57%. Climate variability was estimated to account for 22% of the total reduction in mean annual streamflow, whereas human activities (e.g., proper watershed management practices and associated changes in land use/land cover among other factors) were responsible for 78%; indicating that human activities were the major drivers of changes in the streamflow response. The results of this study point to the potential that reduced wet season flow and improved dry season water availability can be achieved by proper planning and implementation of appropriate watershed management practices.
Trends Analysis of Rainfall and Temperature over Nagwan Watershed, Hazaribagh District, Jharkhand
Current Journal of Applied Science and Technology, 2020
Trend analysis is performed to find the pattern that prevails in Nagwan watershed area located in Hazaribagh district of Jharkhand (India) having very high average annual rainfall in the range of 1146 mm. The study aims to investigated the impacts of global warming by examine precipitation and temperature change over a period. Non-parametric MK test and Sen’s Slope estimator were used to assess the trend in long-term rainfall and temperature time series (1981-2019). The analysis has been carried out on monthly, seasonal and annual scale to identify meso-scale climate change effect on hydrological regime. The precipitation in the summer showed an increasing trend (Z value +1.67) and there was increasing trend in the seasonal rainfall which influences the total water availability in the watershed. There was increase in minimum temperature during summer season which shows the impact of global warming and may results in increasing the duration of the summer season. The annual average mi...
Journal of Water and Climate Change, 2021
Study of rainfall pattern and trend in the long term is essential from climatic change and socioeconomic perspectives. In the present study, monthly, seasonal and annual rainfall of semi-arid regions (Madhya Maharashtra, Marahwada and Vidarbha) of the Godavari basin is evaluated for the period of 1871–2016. The innovative trend analysis (ITA), Mann–Kendall test (MK) and Sen's slope estimator methods are used to check gradual change. A significant increasing or decreasing trend is not detected in the seasonal and annual rainfall series for any of the regions. The rainfall variability index indicates Madhya Maharashtra has received normal rainfall for 40% of the time, Marathwada for 36% of the time and Vidarbha region for 41% of the time. Very dry and very wet conditions are experienced by all three regions for 15% of the time. The spatial and temporal variation in the seasonal and annual rainfall is not significant in these regions. The results obtained from the study will be use...
Acta Geophysica, 2021
Global warming is a biggest issue around the world. In this research paper, the temporal and spatial trend analysis of seasonal and annual rainfall on Bhogavo River watersheds in Sabarmati lower basin of Gujarat state of India has been analysed using the data of 11 rain gauge stations installed in Bhogavo watershed. Linear regression, Mann-Kendall Test, Sen's slope test and innovative trend analysis methods are used to carry out monthly and annual rainfall trend analysis. In addition to the rainfall analysis, a number of rainy days change in magnitude as a percentage of mean rainfall have also been analysed using linear regression and Sen's slope method, respectively. The IDW method is used to develop a spatial distribution of annual and seasonal rainfall trend over the study area. From the results, it is concluded that annual rainfall shown increasing (positive) trend at nine stations out of 11 stations. The highest value of change in magnitude of trend as a percentage of mean monthly rainfall has been obtained in the month of July, attributing increasing trend at Sayla station and lowest value magnitude of trend as a percentage of mean rainfall in the monthly rainfall has been obtained in the month of August, attributing decreasing trend at Bavla station. Keywords Bhogavo River watersheds • Climate change • Innovative trend analysis • Mann-kendall test • Rainfall trend • Temporal and spatial trend Electronic supplementary material The online version of this article (
Streamflow trends in the Mahanadi River basin (India): Linkages to tropical climate variability
Journal of Hydrology, 2013
Mahanadi River basin is one of the recognized climatic vulnerable regions of India. Recent occurrences of the extreme climatic events in this basin underscore the importance of evaluating the trend and variability of hydroclimatic variables in order to understand the potential impact of future change. In this study, the monthly streamflow data for the period 1972-2007 and the daily rainfall data for the period 1972-2005 have been analyzed using the Mann-Kendall nonparametric test after removing serial correlation. The results reveal a substantial spatial and subseasonal difference in the monsoon season streamflow and rainfall patterns, with a predominance of the increasing trends in June and decreasing trends in August. However, a marked increase is observed in the streamflow and rainfall of the pre-and post-monsoon season. The correlation coefficients show a direct correspondence of the rainfall and streamflow series with the El Niño-Southern Oscillation (ENSO), which is contrary to the established inverse relationship over India. The noteworthy feature of this study is the observed climate uncertainty in terms of large variability in the extreme indices since the 1990s, consistent with the warming induced intensification of the hydrological cycle. Strong evidences have emerged regarding the basin-wide increases in extreme rainfall indices. In particular, the coastal sector of the basin is more vulnerable to the heavy rainfall, whereas the southern Eastern Ghats region is susceptible to the moisture stress. The discharge at the basin outlet has declined at a rate of 3388 Â 10 6 m 3 decade À1 , suggesting the need of environmental flow assessment. The results of this study would help the reservoir managers and policy makers in planning and management of water resources of the Mahanadi River basin.
International Journal of Environment and Climate Change
The analysis of stream flow trends of hydro-climatic variables such as stream flow, rainfall, and temperature provides useful information for effective water resource planning, design, and management. Trends in observed stream flow at seven gauging stations in the Ramganga river basin of North India were examined from 1981 to 2012 using the Mann-Kendall and Sen's slope. Lag 1 autocorrelation analyses were used to investigate the relationships between trends in stream flow and rainfall. Annual, monsoonal, and winter seasonal stream flow (p0.05) decreased gradually from upstream to downstream of the river, as did crop seasonal and decadal moving averaged standardized anomalies of streamflow for the entire basin. The streamflow's declining trend was partly attributed to higher water withdrawal, higher air temperature, and higher population, and partly to a significantly declining post-monsoon rainfall trend, particularly upstream and downstream. The changing monsoon rainfall pa...