scholarly journals Analysis of spatio-temporal climate variability of a shallow lake catchment in Tanzania

2020 ◽  
Author(s):  
Latifa O. Nyembo ◽  
Isaac Larbi ◽  
Mwemezi J. Rwiza
Keyword(s):  
Water Productivity ◽  
Standardized Precipitation Index ◽  
Negative Influence ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Adaptation Measures ◽  
Distance Weighting ◽  
Spatio Temporal ◽  
Slope Estimator ◽  
Lake Catchment

Abstract This study analyzed the trends and spatio-temporal variability in rainfall and temperature, and the length of the rainy season (LRS) in the Lake Manyara catchment, Tanzania, covering a period between 1988 and 2018 using stations and satellite climate product. The Mann-Kendall statistical test, Sen's slope estimator, and inverse distance weighting interpolation techniques were used to detect the trends, magnitude of trends and spatial distribution of rainfall and temperature. A modified Stern's method and water balance concept were used for rainfall onset, cessation and LRS analysis, while a standardized precipitation index (SPI) was used to investigate the wetness or dryness of the area. The results showed high variability and decreasing trend (4 mm/y) in annual rainfall, and non-significant increasing trend for minimum and maximum temperature. Rainfall increased from the western to the northern part of the catchment whereas a reversal pattern was noticed for temperature. The SPI shows a signal of normal condition (about 65%) for all stations – with few years showing evidence of wetter and drier conditions. The LRS showed a decreasing trend indicating a potential negative influence on rain-dependent activities. There is a need, therefore, for adaptation measures such as improving water productivity and irrigation at the farm and catchment level.

Biogeographical effects on body mass of native Australian and introduced mice, Pseudomys hermannsburgensis and Mus domesticus: an inquiry into Bergmann's Rule

2008 ◽  
Vol 56 (6) ◽  
pp. 423 ◽  
Author(s):  
Sean Tomlinson ◽  
Philip C. Withers
Keyword(s):  
Ambient Temperature ◽  
Body Mass ◽  
Rainfall Variability ◽  
Negative Influence ◽  
Bergmann’S Rule ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Mus Domesticus ◽  
Arid Areas ◽  
Bergmann's Rule

We investigated interactions of body mass with geographical location, and five climatic measures for two Australian rodents, the native Australian sandy inland mouse (Pseudomys hermannsburgensis) and the introduced house mouse (Mus domesticus). Correlation and regression analyses identified interactions of body mass with latitude, longitude, average highest maximum and lowest minimum temperatures, average annual rainfall, rainfall variability, and aridity. There was a significant correlation of body mass with latitude and longitude for Mus domesticus and P. hermannsburgensis. House mice were heavier in the south and east, and sandy inland mice were heavier in the north and east. M. domesticus conforms to Bergmann’s Rule, while P. hermannsburgensis does not. Maximum temperature, aridity and rainfall variability significantly influenced body mass of M. domesticus, which was heavier at cooler maxima, in less arid areas, and in areas of greater rainfall variability. Only aridity significantly influenced body mass of P. hermannsburgensis, which was heavier in more arid areas. Temperature did not interact significantly with body mass. After accounting for climatic variables, there was still a significant relationship between the residuals of body mass with locality for both species, with a negative influence of latitude and a positive influence of longitude in both; the latitudinal interaction for both species was converse to Bergmann’s Rule. We suggest that latitude, ambient temperature and other selection pressures (such as aridity or productivity) can act in opposing directions, and speculate that the influence of other factors, such as food availability or sociality, may be more important than latitude or ambient temperature.

scholarly journals Spatio-temporal variability of climatic parameters across different altitudes of North- Western Himalaya

2021 ◽  
Vol 21 (3) ◽  
pp. 297-306
Author(s):  
PANKAJ PANWAR ◽  
SHARMISTHA PAL ◽  
NANCY LORIA ◽  
MED RAM VERMA ◽  
N.M. ALAM ◽  
...  
Keyword(s):  
Rainfall Variability ◽  
Management Strategies ◽  
Extreme Rainfall ◽  
Western Himalaya ◽  
Farming System ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Rainfall Occurrence ◽  
Spatio Temporal ◽  
Different Altitudes

Climate change impact varies across different altitudinal ranges and demands local specific management strategies for water resource and farming system management. The present study analyses spacio-temporal climate parameters across different altitudes of Himachal Pradesh a hilly state of India. Analysis shows that annually, minimum temperature has significantly decreased by -0.09°C at altitude I (350 - 400 m) while maximum temperature has significantly increased by 0.05°C at altitudes I and II (1400-1500 m) and decreased significantly by -0.08°C at altitude III (2000- 2100 m). Higher regions Altitude – IV (2900-3000 m) received lowest rainfall (746.1 mm) with 30.2 % variation. Seasonal rainfall variability was higher in post monsoon (102 - 174%) and least in monsoon (21 - 57%). Annual rainfall at altitude I is strongly irregular (PCI 20.1 to 22.3), followed by altitude – IV (PCI 15-25); altitude – II irregular (PCI 15-20) and altitude – III moderate to irregular (PCI 12 -19) rainfall. Seasonal Index values for four altitudes fall between 0.91-0.96 revealed that rainfall is irregular and markedly seasonal with longer drier season. Higher wavelet powers in altitude - I and II after 2005 suggests frequency of extreme rainfall occurrence had increased.

scholarly journals Spatio-temporal analysis of droughts in the Lake Chilwa Basin, Malawi

2021 ◽  
Author(s):  
Oscar Clement Kambombe ◽  
Cosmo Ngongondo ◽  
Levis Eneya ◽  
Maurice Monjerezi ◽  
Clement Boyce
Keyword(s):  
Standardized Precipitation Index ◽  
Temporal Analysis ◽  
Enso Event ◽  
Annual Rainfall ◽  
Drought Severity ◽  
Lake Basin ◽  
Anthropogenic Pressure ◽  
Spatio Temporal ◽  
Lake Chilwa ◽  
The Standardized Precipitation Index

Abstract Drought phenomena are attributed to water availability deficit that is caused by low precipitation. However, droughts are quite complex and cannot simply be defined on the basis of precipitation as other factors may have an influence. In this study, we investigated the spatio-temporal patterns of droughts in Lake Chilwa Basin, an endorheic lake basin that has recently experienced major recurrent lake recessions. The standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI) at six- and twelve-month timescales were used to evaluate drought severity variations from 1970 to 2018, in relation to the recessions. The stationarity difference in rainfall between 1973 to 1995 and 1996 to 2018 and climatological trends were tested using Mann-Whitney and Mann-Kendall tests, respectively. The El Niño Southern Oscilation (ENSO) influence on rainfall was also investigated. In general, the results show a statistically insignificant decreasing rainfall trend, coupled with statistically significant temperature increase (a=0.05). In addition, both indices broadly detected droughts within similar category ranges and variation patterns, suggesting minimal influence of temperature on droughts compared to rainfall. The study also reveals that not every ENSO event leads to low rainfall in the basin. It is further shown that unlike past major recessions e.g., 1994/95, recent lake dry-ups of 2012 and 2015 were as a result of milder droughts. Moreover, the trigger threshold of lake dry-ups is shown to have shifted; such that average annual rainfall below 1000mm is likely to yield a dry-up in recent times than before, which may be attributable to anthropogenic pressure.

scholarly journals Variabilities and Trends of Rainfall, Temperature, and River Flow in Sipi Sub-Catchment on the Slopes of Mt. Elgon, Uganda

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1834
Author(s):  
Justine Kilama Luwa ◽  
Jackson-Gilbert Mwanjalolo Majaliwa ◽  
Yazidhi Bamutaze ◽  
Isa Kabenge ◽  
Petter Pilesjo ◽  
...  
Keyword(s):  
Land Use ◽  
Trend Analysis ◽  
Coefficient Of Variation ◽  
River Flow ◽  
Land Use Changes ◽  
Standardized Precipitation Index ◽  
Daily Rainfall ◽  
Annual Rainfall ◽  
Slope Estimator ◽  
The Standardized Precipitation Index

The variabilities in rainfall and temperature in a catchment affect water availability and sustainability. This study assessed the variabilities in rainfall and temperature (1981–2015) and river flow (1998–2015) in the Sipi sub-catchment on annual and seasonal scales. Observed daily rainfall and temperature data for Buginyanya and Kapchorwa weather stations were obtained from the Uganda National Meteorological Authority (UNMA), while the daily river-flow data for Sipi were obtained from the Ministry of Water and Environment (MWE). The study used descriptive statistics, the Standardized Precipitation Index (SPI), Mann–Kendall trend analysis, and Sen’s slope estimator. Results indicate a high coefficient of variation (CV) (CV > 30) for August, September, October, and November (ASON) seasonal rainfall, while annual rainfall had a moderate coefficient of variation (20 ˂ CV ˂ 30). The trend analysis shows that ASON minimum and mean temperatures increased at α = 0.001 and α = 0.05 levels of significance respectively in both stations and over the entire catchment. Furthermore, annual and March, April, and May (MAM) river flows increased at an α = 0.05 level of significance. A total of 14 extremely wet and dry events occurred in the sub-catchment during the post-2000 period, as compared to five in the pre-2000. The significant increased trend of river flow could be attributed to the impacts of climate and land-use changes. Therefore, future studies may need to quantify the impacts of future climate and land-use changes on water resources in the sub-catchment.

scholarly journals Variabilidad espacio-temporal de las sequías en la cuenca Pacífico Norte de México (1961-2010)

2016 ◽  
Vol 42 (1) ◽  
pp. 185 ◽  
Author(s):  
L. Serrano-Barrios ◽  
S. M. Vicente-Serrano ◽  
H. Flores-Magdaleno ◽  
L. Tijerina-Chávez ◽  
D. Vázquez-Soto
Keyword(s):  
Standardized Precipitation Index ◽  
Maximum Temperature ◽  
Drought Indices ◽  
Drought Severity ◽  
Evaporative Demand ◽  
The North ◽  
Weather Stations ◽  
Potential Impact ◽  
Spatio Temporal ◽  
The Standardized Precipitation Index

This article analyses the spatio-temporal variability of droughts in the North Pacific Basin of México between 1961 and 2010, using two drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). We used data from 48 weather stations with available data of precipitation and monthly minimum and maximum temperature. In 22 of the weather stations, time series of Piché evaporation were also available. The reference evapotranspiration, necessary to obtain the SPEI, was calculated by means of the Hargreaves equation. Results show that major droughts occurred in the 1980s and 2000s, although there is a noticeable spatial variability across the region. Finally, the potential impact of the atmospheric evaporative demand on drought severity observed by the different drought indices is discussed, and the possible implications for an appropriate risk assessment.

scholarly journals Trend and variability analysis of rainfall and temperature in the Tana basin region, Ethiopia

2018 ◽  
Vol 9 (3) ◽  
pp. 555-569 ◽  
Author(s):  
Hailu Birara ◽  
R. P. Pandey ◽  
S. K. Mishra
Keyword(s):  
Climate Variability ◽  
Kendall Test ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Positive Trend ◽  
Distance Weighted ◽  
Slope Estimator ◽  
Basin Region ◽  
Annual Maximum Temperature ◽  
Inverse Distance

Abstract Global warming and climate variability are emerging as the foremost environmental problems in the 21st century, particularly in developing countries. Ethiopia is one of the countries located in the sub-Sahara region and climate variability has a significant impact on the economy of the country. The aim of this study is to characterize annual and seasonal rainfall and annual temperature variability, and to measure trends on both the spatial and the temporal scale for ten selected stations in the Tana basin region, Ethiopia. The Mann–Kendall test and Sen's slope estimator were used to assess trends and variability of rainfall and temperature. The spatial distribution of rainfall and temperature was determined using the inverse distance weighted technique. Results indicated that the amount of rainfall decreased for the majority of the stations. The annual rainfall showed significant decreasing trends with a magnitude ranging from −5.92 mm/year at Injibara to −9.74 mm/year in Wegera. However, a positive trend of annual rainfall was observed at Addis Zemen (1.81 mm/year). The minimum, maximum and mean temperatures have increased significantly for most of the stations. An increasing trend of annual maximum temperature was obtained between 1980 and 2015; an increase of 1.08°C was observed.

scholarly journals Hydroclimatic Variability in the Bilate Watershed, Ethiopia

Climate ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 98
Author(s):  
Yoseph Arba Orke ◽  
Ming-Hsu Li
Keyword(s):  
Water Resource Management ◽  
Significant Rise ◽  
Maximum Temperature ◽  
Trend Test ◽  
Adaptation Measures ◽  
Crucial Information ◽  
Slope Estimator ◽  
Hydroclimatic Variability ◽  
Increasing Temperature ◽  
Point Detection

It is important to understand variations in hydro-meteorological variables to provide crucial information for water resource management and agricultural operation. This study aims to provide comprehensive investigations of hydroclimatic variability in the Bilate watershed for the period 1986 to 2015. Coefficient of variation (CV) and the standardized anomaly index (SAI) were used to assess the variability of rainfall, temperature, and streamflow. Changing point detection, the Mann–Kendell test, and the Sen’s slope estimator were employed to detect shifting points and trends, respectively. Rainfall and streamflow exhibited higher variability in the Bega (dry) and Belg (minor rainy) seasons than in the Kiremt (main rainy) season. Temperature showed an upward shift of 0.91 °C in the early 1990s. Reduction in rainfall (−11%) and streamflow (−42%) were found after changing points around late 1990s and 2000s, respectively. The changing points detected were likely related to the ENSO episodes. The trend test indicated a significant rise in temperature with a faster increase in the minimum temperature (0.06 °C/year) than the maximum temperature (0.02 °C/year). Both annual mean rainfall and streamflow showed significant decreasing trends of 8.32 mm/year and 3.64 mm/year, respectively. With significant increase in temperature and reduction in rainfall, the watershed has been experiencing a decline in streamflow and a shortage of available water. Adaptation measures should be developed by taking the increasing temperature and the declining and erratic nature of rainfall into consideration for water management and agricultural activities.

scholarly journals Farmers' Perception, Adaptation Strategies, their Determinants and Barriers to Climate Change in the Bundelkhand Region of Central India

2021 ◽  
pp. 239-257
Author(s):  
S. K. Rai ◽  
Sunil Kumar ◽  
P. K. Ghosh ◽  
. Satyapriya ◽  
P. Govindasamy ◽  
...  
Keyword(s):  
Climate Change ◽  
Central India ◽  
Adaptation Strategies ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Adaptation Measures ◽  
Extension Services ◽  
Educational Qualification ◽  
Dry Spell ◽  
Increasing Trend

This study is based on a farm house hold survey (818 households) collected from 4 districts of drought prone region of central India and examines that how farmers perceive the climate change and adaptation strategies adopted over the past few decades. Nearly, 80.9%, 93.6% and 95.2% farmers’ perceived that the average temperature has increased, rainfall has decreased and occurrence of drought is more frequent, respectively during last 25–30 years. A significant decreasing trend was observed in annual rainfall at all the studied locations with a rate of 2.1 to 5.8 mm year–1. In most of the locations both maximum and minimum temperature showed an increasing trend during winter season (July-October) in the range of 0.8 to 1.2 and 0.4–1.5ºC per 100 year, respectively. However, only two locations viz., Jhansi and Banda district showed increasing trend in maximum temperature in the range of 0.8 to 2.3oC per hundred years during rainy season. This study revealed that the perceptions of rural farmers on climate change and variability are consistent with the climate trend analysis. Econometric model suggested a positive influence of age, agriculture experience, educational qualification, size of land holding, adequate access to credit facility and crop insurance, intermittent dry spell and adequate extension services on climate change perceptions and adaptation. The results further revealed that 69.8% respondent have implemented adaptation measures in response to dry spell. Furthermore, analysis showed that agriculture experience, educational qualification and intermittent dry spell and access to extension services are the key factors for adoption of various adaptation strategies particularly, irrigations scheduling, use of high yielding improved varieties, pesticides and change of planting date. Inadequate availability of irrigation resources and frequent drought as well as intermittent dry spells were considered as the most critical barriers for adaptation measures to climate change by farmers.

How to assess the vulnerability and the risk of flooding of the most important catchment in the Republic of Djibouti?

2021 ◽  
Author(s):  
Golab Moussa Omar ◽  
Jean-Emmanuel Paturel ◽  
Christian Salles ◽  
Gil Mahe ◽  
Mohamed Jalludin
Keyword(s):  
Temporal Variability ◽  
Groundwater Resources ◽  
Annual Rainfall ◽  
Series Data ◽  
Boreal Summer ◽  
Precipitation Regime ◽  
Daily Data ◽  
Spatio Temporal ◽  
The Republic ◽  
Rainy Days

<p><span>This study focus on the catchment of Ambouli wadi which is one of the country’s largest watersheds covering 794 km² (3.5 % of the total area of the Republic of Djibouti). Because of its groundwater resources, this exoreic watershed is of major importance. Indeed, the aquifer is the main source of drinking water supply for the city of Djibouti-city. In addition, this wadi is also responsible for floods causing human suffering and severe economic damages. Despite the importance of the catchment for the development of Djibouti-city, Ambouli wadi has been the subject of few scientific studies. This partly explains the scarcity of rainfall stations and therefore data in this area. Analysis of the spatio-temporal variability of rainfall is required to assess the risk of flooding. </span></p><p><span>In an arid country like the Republic of Djibouti flash floods are an important concern for the management of water resources systems and risk prevention and protection. The desertic climate of the country is characterized by high levels of temperature and evaporation, and also by very weak and irregular annual rainfall, distributed in two major seasons : a cooler season (from October to March) with high relative humidity and low temperatures comprised between 22°C and 30°C, and a hot and dry season (from June to September). </span></p><p><span>Rain data were collected from a network of 9 raingauge stations at different time scales, from monthly to hourly. These data are provided by the national meteorological agency (4 stations) and the early warning system of CERD National Research Center (5 stations).</span></p><p><span> </span><span>The spatio-temporal variability of rainfall, is characterized using the Standardized Precipitation Index (SPI) and the analysis of rainfall normals over 30 years (1951-1980 and 1961-1990). Long time series data were available from 4 of the 9 stations: (Djibouti-serpent, Djibouti-aeorodrome, Oueah and Arta). At annual scale, the variability is clearly described by a succession of dry and humid years. Also, the monthly rainfall clearly demonstrates the well-known bimodal precipitation regime of east Africa. It shows, two peaks corresponding to the « long rain » and the « short rain » rainy seasons, which correspond to the period of March-April-May and of October-November-December, respectively. On the other hand, we also observe a dry period which is characterized by a rainfall deficit (negative rainfall index for almost all the stations) corresponding to the boreal summer (June to September). </span><span>Daily data is currently collecting from the Djibouti-aerodrome station (1981-2017) for a better understanding of the precipitation regime. Rainy days are computed from daily data (rainfall > 1 mm) and we find an annual average of 11 wet days with a minimum in 1988 (1 rainy day) and a maximum in 1993 (23 rainy days). </span></p>

scholarly journals Spatio-temporal modeling of surface runoff in ungauged sub-catchments of Subarnarekha river basin using SWAT

MAUSAM ◽  
2021 ◽  
Vol 72 (3) ◽  
pp. 597-606
Author(s):  
CHINMAYA PANDA ◽  
DWARIKA MOHAN DAS ◽  
B. C. SAHOO ◽  
B. PANIGRAHI ◽  
K. K. SINGH
Keyword(s):  
Surface Runoff ◽  
Assessment Tool ◽  
Nutrient Loss ◽  
Coefficient Of Determination ◽  
Annual Rainfall ◽  
Model Parameters ◽  
Runoff Generation ◽  
Temporal Modeling ◽  
Spatio Temporal ◽  
R Factors

In this present study, Soil and Water Assessment Tool (SWAT) embedded with ArcGIS interface has been used to simulate the surface runoff from the un-gauged sub-catchments in the upper catchment of Subarnarekha basin. Model calibration and validation were performed with the help of Sequential Uncertainty Fitting (SUFI-2) in-built in the SWAT-CUP package (SWAT Calibration Uncertainty Programs). The model was calibrated for a period from 1996 to 2008 with 3 years warm up period (1996-1998) and validated for a period of 5 years from 2009 to 2013. The model evaluation was performed by Nash - Sutcliffe coefficient (NSE), Coefficient of determination (R2) and Percentage Bias (PBIAS). The degree of uncertainty was evaluated by P and R factors. Basing upon the R2, NSE and PBIAS values respectively, of the order of 0.90, 0.90 and -12%, during calibration and 0.85, 0.83 and -15% during validation, substantiate performance of the model. All uncertainties of model parameters have been well taken by the P and R factors respectively, of the order of 0.95 and 0.77 during calibration and 0.82 and 0.87 during validation. The runoff generation from 19 sub-catchments of Adityapur catchment varies from 29.2-44.1% of the annual rainfall and average surface runoff simulated for the entire catchment is 545 mm. As the surface runoff generated in most of the sub-catchments amounts to above 30% of rainfall, it is recommended for adequate number of structural interventions at appropriate locations in the catchment to store the rainfall excess for providing irrigation, recharging groundwater and restricting the sediment and nutrient loss.

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