scholarly journals Analysis of Intra and Interseasonal Rainfall Variability and Its Effects on Pearl Millet Yield in a Semiarid Agroclimate: Significance of Scattered Fields and Tied Ridges

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 578 ◽  
Author(s):  
Festo Silungwe ◽  
Frieder Graef ◽  
Sonoko Bellingrath-Kimura ◽  
Siza Tumbo ◽  
Frederick Kahimba ◽  
...  
Keyword(s):  
Pearl Millet ◽  
Crop Production ◽  
Rainfall Variability ◽  
Daily Rainfall ◽  
Rain Gauge ◽  
Seasonal Rainfall ◽  
African Countries ◽  
Climate Conditions ◽  
Semiarid Areas ◽  
Millet Yield

Establishing food security in sub-Saharan African countries requires a comprehensive and high resolution understanding of the driving factors of crop production. Poor soil and adverse climate conditions are among the major drivers of poor regional crop production. Drought and rainfall variability challenges are not fully being addressed by rainfed producers in semiarid areas. In this study, we analysed the spatiotemporal rainfall variability (STRV) and its effects on pearl millet yield using two seasons of data collected from 38 rain gauge stations scattered randomly in farm plots within a 1500 ha area of semiarid central Tanzania. The STRV effects on pearl millet yield under flat and tied ridge management were analysed. Our results show that seasonal rainfall can vary significantly for neighboring fields at distances of less than 200 m, which impacts yield. The STRV for daily rainfall was found to be more critical than for total seasonal rainfall amounts. Scattering fields can help farmers avoid total harvest loss by obtaining at least some yield from the areas that received adequate rain. The use of tied ridges is recommended to conserve soil moisture and improve yields more than flat cultivation in semiarid areas.

scholarly journals TEMPORAL RAINFALL DISAGGREGATION BY A SIMPLE RANDOM CASCADE MODEL

2018 ◽  
Vol 80 (6) ◽  
Author(s):  
Siti Mariam Saad ◽  
Abdul Aziz Jemain ◽  
Noriszura Ismail
Keyword(s):  
Rainfall Variability ◽  
Daily Rainfall ◽  
Poisson Model ◽  
Rain Gauge ◽  
Peninsular Malaysia ◽  
Cascade Model ◽  
Statistical Measures ◽  
Hourly Rainfall ◽  
Cascade Models ◽  
Log Normal

This study evaluates the utility and suitability of a simple discrete multiplicative random cascade model for temporal rainfall disaggregation. Two of a simple random cascade model, namely log-Poisson and log-Normal  models are applied to simulate hourly rainfall from daily rainfall at seven rain gauge stations in Peninsular Malaysia. The cascade models are evaluated based on the capability to simulate data that preserve three important properties of observed rainfall: rainfall variability, intermittency and extreme events. The results show that both cascade models are able to simulate reasonably well the commonly used statistical measures for rainfall variability (e.g. mean and standard deviation) of hourly rainfall. With respect to rainfall intermittency, even though both models are underestimated, the observed dry proportion, log-Normal  model is likely to simulate number of dry spells better than log-Poisson model. In terms of rainfall extremes, it is demonstrated that log-Poisson and log-Normal  models gave a satisfactory performance for most of the studied stations herein, except for Dungun and Kuala Krai stations, which both located in the east part of Peninsula.

scholarly journals Temporal rainfall trend analysis in different agro-ecological regions of southern Africa

Water SA ◽  
2021 ◽  
Vol 47 (4 October) ◽  
Author(s):  
W Mupangwa ◽  
R Makanza ◽  
L Chipindu ◽  
M Moeletsi ◽  
S Mkuhlani ◽  
...  
Keyword(s):  
Southern Africa ◽  
Linear Trend ◽  
Rainfall Variability ◽  
Daily Rainfall ◽  
Farming Systems ◽  
Seasonal Rainfall ◽  
Smallholder Farming ◽  
Significant Linear Trend ◽  
Semi Arid ◽  
Linear Trends

Rainfall is a major driver of food production in rainfed smallholder farming systems. This study was conducted to assess linear trends in (i) different daily rainfall amounts (<5, 5–10, 11–20, 21–40 and >40 mm∙day-1), and (ii) monthly and seasonal rainfall amounts. Drought was determined using the rainfall variability index. Daily rainfall data were derived from 18 meteorological stations in southern Africa. Daily rainfall was dominated by <5 mm∙day-1 followed by 5–10 mm∙day-1. Three locations experienced increasing linear trends of <5 mm∙day-1 amounts and two others in sub-humid region had increases in the >40 mm day-1 category. Semi-arid location experienced increasing trends in <5 and 5–10 mm∙day-1 events. A significant linear trend in seasonal rainfall occurred at two locations with decreasing rainfall (1.24 and 3 mm∙season-1). A 3 mm∙season-1 decrease in seasonal rainfall was experienced under semi-arid conditions. There were no apparent linear trends in monthly and seasonal rainfall at 15 of the 18 locations studied. Drought frequencies varied with location and were 50% or higher during the November–March growing season. Rainfall trends were location and agro-ecology specific, but most of the locations studied did not experience significant changes between the 1900s and 2000s.

scholarly journals Indicator-Based Assessment of Drought in Bhilwara District, Rajasthan

2021 ◽  
pp. 141-153
Author(s):  
Gaurav Sharma ◽  
Chandra Kishor Kumar ◽  
Rishi Pathak
Keyword(s):  
Indian Monsoon ◽  
Rainfall Variability ◽  
Daily Rainfall ◽  
Rain Gauge ◽  
Annual Rainfall ◽  
Drought Frequency ◽  
Arid Conditions ◽  
Dry Spells ◽  
Water Scarce ◽  
Rainfall Departure

Management of water resources helps to sustain even in drastic conditions resulted due to unprecedented disruption in rainfall patterns. Change and irregularity in the pattern of the Indian monsoon are the outcomes of human-induced activities. Inadequate water availability affecting various sectors namely domestic, industrial, and agricultural sectors that are dependent upon it. To cope under such drastic conditions adaptability and planning prior to its occurrence plays a significant role. It is under this context, the present study investigated drought characteristics which include drought frequency and severity caused by prolonged dry spells in Bhilwara district, Rajasthan. The district falls in the water-scarce regions with arid to semi-arid conditions and with an average annual rainfall of 658.03 mm. Due to high rainfall variability, the region is frequently subsumed under drought-like conditions. Comprehensive analysis using daily rainfall data from 1973-2018 for 12 rain gauge stations in Bhilwara district has been carried out. Most of the stations were drought-prone assessed by probability analysis using Weibull’s plotting position formula. The departure analysis showed that Kotri station has a maximum drought frequency of 1 in 2 years while other stations were having a drought frequency of 1 in 3 to 4 years. Prioritization of drought-prone stations based on rainfall departure analysis helps to initiate an immediate mitigation process based on the ranking of its proneness. Asind and Bhilwara station with RDI 0.91 has maximum proneness and its calls for effective planning for drought management. Based on seasonal departure analysis it is found that 1980, 1981, 1985, 1987, 2000, 2002, 2008, 2015, and 2017 are drought years. The result has been supplemented using NDVI so that the vegetation condition can also be assessed during water stress conditions. The study highlighted that the frequency of drought has increased owing due to climate change and thus, poses serious challenges if not tackle adequately.

scholarly journals Performance of Sorghum Varieties under Variable Rainfall in Central Tanzania

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Barnabas M. Msongaleli ◽  
S. D. Tumbo ◽  
N. I. Kihupi ◽  
Filbert B. Rwehumbiza
Keyword(s):  
Crop Production ◽  
Rainfall Variability ◽  
Growing Season ◽  
Moisture Stress ◽  
Crop Failure ◽  
Rainfall Distribution ◽  
Cropping Season ◽  
Dry Spells ◽  
Semiarid Areas

Rainfall variability has a significant impact on crop production with manifestations in frequent crop failure in semiarid areas. This study used the parameterized APSIM crop model to investigate how rainfall variability may affect yields of improved sorghum varieties based on long-term historical rainfall and projected climate. Analyses of historical rainfall indicate a mix of nonsignificant and significant trends on the onset, cessation, and length of the growing season. The study confirmed that rainfall variability indeed affects yields of improved sorghum varieties. Further analyses of simulated sorghum yields based on seasonal rainfall distribution indicate the concurrence of lower grain yields with the 10-day dry spells during the cropping season. Simulation results for future sorghum response, however, show that impacts of rainfall variability on sorghum will be overridden by temperature increase. We conclude that, in the event where harms imposed by moisture stress in the study area are not abated, even improved sorghum varieties are likely to perform poorly.

Improving crop water use in West Africa in the context of climate change

2020 ◽  
Author(s):  
Sehouevi Mawuton David Agoungbome ◽  
Nick van de Giesen ◽  
Frank Ohene Annor ◽  
Marie-Claire ten Veldhuis
Keyword(s):  
Climate Change ◽  
West Africa ◽  
Water Use ◽  
Crop Production ◽  
Rainfall Variability ◽  
Water Productivity ◽  
Yield Response ◽  
Crop Water ◽  
Climate Conditions ◽  
Crop Water Use

&lt;p&gt;Africa&amp;#8217;s population is growing fast and is expected to double by 2050, meaning the food production must follow the cadence in order to meet the demand. However, one of the major challenges of agriculture in Africa is productivity (World Bank, 2009; IFRI, 2016). For instance, more than 40 million hectares of farmland were dedicated to maize in Africa in 2017 (approx. 20% of world total maize farms), but only 7.4% of the total world maize production came from the African continent (FAO, 2017). This shows the poor productivity which has its causes rooted in lack of good climate and weather information, slow technology uptake and financial support for farmers. In West Africa, where more than 70% of crop production is rain-fed, millions of farmers depend on rainfall, yet the region is one of the most vulnerable and least monitored in terms of climate change and rainfall variability. With a high uncertainty of future climate conditions in the region, one must foresee the big challenges ahead: farmers will be exposed to a lot of damages and losses leading to food insecurity resulting in famine and poverty if measures are not put in place to improve productivity. This study aims at addressing low productivity in agriculture by providing farmers with the right moment to start farming in order to improve efficiency and productivity of crop water use. By analyzing yield response to water availability of specific crops using AquaCrop, the Food and Agriculture Organization crop growth model, we investigate the crop water productivity variability throughout the rainy season and come up with recommendations that help optimize rainfall water use and maximize crop yield.&lt;/p&gt;

scholarly journals Weather Types and Rainfall over Senegal. Part I: Observational Analysis

2008 ◽  
Vol 21 (2) ◽  
pp. 266-287 ◽  
Author(s):  
Vincent Moron ◽  
Andrew W. Robertson ◽  
M. Neil Ward ◽  
Ousmane Ndiaye
Keyword(s):  
Rainfall Variability ◽  
Regional Scale ◽  
Daily Rainfall ◽  
Weather Type ◽  
Seasonal Rainfall ◽  
Boreal Summer ◽  
Frequency Of Occurrence ◽  
Weather Types ◽  
Western Sahel ◽  
Type Frequency

Abstract A k-means cluster analysis is used to summarize unfiltered daily atmospheric variability at regional scale over the western Sahel and eastern tropical North Atlantic during the boreal summer season [July–September (JAS)] 1961–98. The analysis employs zonal and meridional regional wind fields at 925, 700, and 200 hPa from the European Centre for Medium-Range Weather Forecasts reanalyses. An eight-cluster solution is shown to yield an integrated view of the complex regional circulation variability, without the need for explicit time filtering. Five of the weather types identified characterize mostly typical phases of westward-moving wave disturbances, such as African easterly waves (AEWs), and persistent monsoon surges, while the three others describe mostly different stages of the seasonal cycle. Their temporal sequencing describes a systematic monsoonal evolution, together with considerable variability at subseasonal and interannual time scales. Daily rainfall occurrence at 13 gauge stations in Senegal is found to be moderately well conditioned by the eight weather types, with positive rainfall anomalies usually associated with southerly wind anomalies at 925 hPa. Interannual variability of daily rainfall frequency is shown to depend substantially on the frequency of occurrence of weather types specific to the beginning and end of the JAS season, together with the number of persistent monsoon surges over the western Sahel. In contrast, year-to-year changes in the frequency of the weather types mostly associated with westward-moving waves such as AEWs are not found to influence seasonal frequency of occurrence of daily rainfall substantially. The fraction of seasonal rainfall variability related to weather-type frequency is found to have a strong relationship with tropical Pacific sea surface temperatures (SSTs): an El Niño (La Niña) event tends to be associated with a higher (lower) frequency of dry weather types during early and late JAS season with enhanced trade winds over the western Sahel, together with lower (higher) prevalence of persistent monsoon surges. The component of seasonal rainfall variability not related to weather-type frequency is characterized by changes in rainfall probability within each weather type, especially those occurring in the core of the JAS season; it exhibits a larger decadal component that is associated with an SST pattern previously identified with recent observed trends in Sahel rainfall.

scholarly journals Easterly wave contributions to seasonal rainfall over the tropical Americas in observations and a regional climate model

2019 ◽  
Vol 54 (1-2) ◽  
pp. 191-209 ◽  
Author(s):  
Christian Dominguez ◽  
James M. Done ◽  
Cindy L. Bruyère
Keyword(s):  
South America ◽  
Climate Model ◽  
Negative Impact ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Rain Gauge ◽  
Regional Model ◽  
Seasonal Rainfall ◽  
Seasonal Precipitation ◽  
Northern South America

Abstract Easterly waves (EWs) are important moisture carriers and their variability can impact the total May–November rainfall, defined as seasonal precipitation, over the Tropical Americas. The contribution of EWs to the seasonal precipitation is explored over the tropical Americas using rain gauge stations, reanalysis data and a regional model ensemble during the 1980–2013 period. In the present study, EWs are found to produce up to 50% of seasonal rainfall mainly over the north of South America and contribute substantially to interannual regional rainfall variability. An observational analysis shows that the El Niño Southern Oscillation (ENSO) affects EW frequency and therefore, their contribution to seasonal rainfall. In recent years, tropical cyclone (TC) activity over the Main Development Region (MDR) of the tropical North Atlantic has a negative impact on regional seasonal precipitation over northern South America. High TC activity over MDR corresponds to below-normal precipitation because it reduces the EW activity reaching northern South America through the recurving of TC tracks. Recurving TC tracks redirect moisture away from the tropical belt and into the mid-latitudes. However, this relationship only holds under neutral ENSO conditions and the positive phase of the Atlantic Multidecadal Oscillation. A 10-member regional model multi-physics ensemble simulation for the period 1990–2000 was analyzed to show the relationships are robust to different representations of physical processes. This new understanding of seasonal rainfall over the tropical Americas may support improved regional seasonal and climate outlooks.

scholarly journals An Investigation of Warm-Season Spatial Rainfall Variability in Oklahoma City: Possible Linkages to Urbanization and Prevailing Wind

2009 ◽  
Vol 48 (2) ◽  
pp. 251-269 ◽  
Author(s):  
Lauren M. Hand ◽  
J. Marshall Shepherd
Keyword(s):  
Rainfall Variability ◽  
Warm Season ◽  
Daily Rainfall ◽  
Tropical Rainfall Measuring Mission ◽  
Rain Gauge ◽  
Rainfall Anomaly ◽  
Reanalysis Data ◽  
Oklahoma City ◽  
Prevailing Wind ◽  
Rainfall Estimates

Abstract This study used 9 yr (1998–2006) of warm-season (June–September) mean daily cumulative rainfall data from both the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis and rain gauge stations to examine spatial variability in warm-season rainfall events around Oklahoma City (OKC). It was hypothesized that with warm-season rainfall variability, under weakly forced conditions, a rainfall anomaly would be present in climatological downwind areas of OKC. Results from both satellite and gauge-based analyses revealed that the north-northeastern (NNE) regions of the metropolitan OKC area were statistically wetter than other regions. Climatological sounding and reanalysis data revealed that, on average, the NNE area of OKC was the climatologically downwind region, confirming that precipitation modification by the urban environment may be more dominant than agricultural/topographic influences on weakly forced days. The study also established that satellite precipitation estimates capture spatial rainfall variability as well as traditional ground-based resources do. TRMM products slightly underestimate the precipitation recorded by gauges, but the correlation R improves dramatically when the analysis is restricted to mean daily rainfall estimates from OKC urban grid cells containing multiple gauge stations (R2 = 0.878). It was also quantitatively confirmed, using a relatively new concentration factor analysis, that prevailing wind–rainfall yields were consistent with the overall framework of an urban rainfall effect. Overall, the study establishes a prototype method for utilizing satellite-based rainfall estimates to examine rainfall modification by urbanization on global scales and in parts of the world that are not well instrumented with rain gauge or radar networks.

scholarly journals Defining Intraseasonal Rainfall Variability within the North American Monsoon

2006 ◽  
Vol 19 (17) ◽  
pp. 4243-4253 ◽  
Author(s):  
Phil J. Englehart ◽  
Arthur V. Douglas
Keyword(s):  
North American ◽  
Linear Trend ◽  
Monsoon Season ◽  
Rainfall Variability ◽  
Daily Rainfall ◽  
Principal Component ◽  
Seasonal Rainfall ◽  
North American Monsoon ◽  
The North ◽  
The Pacific

Abstract This study provides an empirical description of intraseasonal rainfall variability within the North American monsoon (NAM) region. Applying particular definitions to historical daily rainfall observations, it demonstrates that distinct intraseasonal rainfall modes exist and that these modes differ considerably from the monsoon core region in northwest Sonora (SON), California, to its northward extension in southeast Arizona (AZ). To characterize intraseasonal rainfall variability (ISV), separate P-mode principal component (PC) analyses were performed for SON and AZ. The results indicate that in each area, much of the ISV in rainfall can be described by three orthogonal modes. The correlations between ISV modes and total seasonal rainfall reinforce the notion of differing behaviors between the monsoon’s core and extension. For SON all three ISV modes exhibit significant correlation with seasonal rainfall, with the strongest relationship in evidence for the ISV mode, which is related to rainfall intensity. For AZ, total rainfall exhibits the strongest correlation with the ISV mode, which emphasizes season length and rainfall consistency. Examination of longer-period behavior in the ISV modes indicates that, for SON, there is a positive linear trend in intensity, but a countervailing trend toward a shorter monsoon season along with less consistent rainfall in the form of shorter wet spells. For AZ, the evidence for trend in the ISV modes is not nearly as compelling, though one of the modes appears to exhibit distinct multidecadal variability. This study also evaluates teleconnectivity between ENSO, the Pacific decadal oscillation (PDO), and the NAM’s intraseasonal rainfall variability. Results indicate that part of the intraseasonal rainfall variability in both SON and AZ is connected to ENSO while only SON exhibits a teleconnection with the long-period fluctuations of the PDO.

Spatiotemporal trend analysis of rainfall and temperature, and its implications for crop production

2018 ◽  
Vol 10 (4) ◽  
pp. 799-817 ◽  
Author(s):  
Tesfa Worku ◽  
Deepak Khare ◽  
S. K. Tripathi
Keyword(s):  
Correlation Analysis ◽  
Crop Production ◽  
Rainfall Variability ◽  
Pearson Correlation ◽  
Winter Season ◽  
Seasonal Rainfall ◽  
Annual Rainfall ◽  
Precipitation Concentration Index ◽  
Mk Test ◽  
The Impact

Abstract Global warming is a significant global environmental problem in the 21st century. The problem is high in developing countries, particularly sub-Saharan countries in which the majority of the population live on rainfed agriculture. The present study aimed to undertake spatiotemporal analysis of seasonal and annual rainfall and temperature and its implications. The MK test, Sen's slope and precipitation concentration index (PCI) were applied. Finally, Pearson correlation analysis between climatic variables and crop production was analysed. The Mann–Kendall test results showed that the annual and seasonal rainfall trend was highly variable. The minimum and maximum temperatures have increased by 0.8 and 1.1 °C/year, respectively. Based on PCI results, rainfall during the summer and spring seasons is moderately distributed as compared to annual and winter season rainfall. Based on these observations, the rainfall pattern and distribution of the area could be classified as irregular and erratic distribution. Results of correlation analysis between monthly and seasonal rainfall with crop production were insufficient to conclude the impact of rainfall and temperature on crop production. In view of this, the incidence of food shortage is a common occurrence. Therefore, depending on the historical trend of rainfall variability and prolonged temperature increase, appropriate coping and adaptation strategies need to be encouraged.

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