Impact Of Rainfall Variability Research Articles

Impacts of Rainfall Variability on Streamflow in the Drylands of Northern Kenya: Assessing Water Availability under a Changing Climate

Water availability is a function of climatic and land surface conditions, which determine the amount and distribution of atmospheric water as it reaches the surface. This largely depends on rainfall, whose variability affects water, food and livelihood security. This paper sought to quantify the effects of rainfall variability on water availability in an effort to support effective water resources management. Coefficient of Variation (CV), Standardized Anomaly Index (SAI) and Mann-Kendall trend test approaches were used to assess variability and trends, while correlation and regression analysis were employed to determine effects of rainfall variability on streamflow. A hydrological model, Soil and Water Assessment Tool (SWAT), was used to simulate streamflow with a view to assessing water availability under two climate change scenarios; Representative Concentration Pathways (RCP) 4.5 and 8.5. Results show that the area experiences moderate to extreme rainfall variability, as indicated by CV and SAI values that ranged from 20 to 99% and -2.5 to +3 respectively, resulting in moderate to extreme floods and droughts that often disrupt livelihoods. Current streamflow simulations (1981 – 2020) indicated increasing trends. Near and far future streamflow volumes will decrease by 15% during the April-May-June season while during October-November-December season they will increase by 13%, compared to the present. Increasing trends of rainfall and streamflow indicate that the area has opportunities for rainwater harvesting while the high variability indicates a need for early warning systems to cushion communities from climatic shocks evidenced by the impacts of climate extremes experienced in the area.

Impacts of rainfall variability in Gharb plain: Morocco

The Mediterranean climate is characterized by irregular rainfall, leading to both severe droughts and occasional flooding. This research aims to examine the changes occurring in the rainfall regime of the Gharb plain over thirty-three years, with specific attention given to three sites: El Menasra, Bel Ksiri, and Sidi Slimane. A range of methods were employed to understand the dimensions and impacts of rainfall in the study area. These methods include trend detection, testing for breaks, analysis of reduced annual anomalies, utilization of the Hyrfan Plus software, calculation of the Martone aridity index, assessment of the standardized rainfall index, and mapping flood zones. The findings of this study revealed that the Gharb Plain experienced periods of rainfall deficits, resulting in drought conditions during years with below-average rainfall. Conversely, years with above-average rainfall exhibited severe flooding, indicating the occurrence of two extreme phenomena that necessitate effective hydraulic management strategies. The main results showed that the rainfall trend is regressing, as the Nicholson, Martone, Emberger, and standardized precipitation indexes justify this regression. In addition, the plain has received an immense quantity of water from the Rif and Atlas Mountains, with the result that the study area has from time to time experienced severe flooding, as shown by the return periods detected, The Gharb plain has therefore experienced a rainfall deficit (drought) in years with below-average rainfall, while years with above-average rainfall have seen severe flooding, putting the country under two extreme phenomena requiring hydraulic management.

The impact of rainfall variability and crop production on vertisols in the central highlands of Ethiopia

BackgroundUnderstanding the yearly, seasonal, monthly, and weekly rainfall variability is crucial for improved agricultural practice in Ethiopia, where agriculture depends on rainfall. In particular, knowledge of rainfall onset, withdrawal, amount, distribution, and the length of the crop growing period would protect farmers from crop damage due to climatic anomalies. This study collected and described 39 years of rainfall data using the Markov chain model. Based on the rainfall probability levels at different threshold values, the length of the dry and wet spells and the length of the growing period were determined.ResultsThe study shows dependable rainfall at a 75% probability level commences in June. The chance of receiving greater than 10 mm at a 50% probability level starts in week 10 (5 March–11 March), with much discontinuity up to week 21st (21 May–27 May). The dependable weekly rainfall begins the week of 22 May (28th May–3rd June) with a probability of greater than 20 mm. The study revealed that the short rainy season rainfall (February to May) is unreliable for growing crops at Ghinchi as opposed to other highland areas of Ethiopia. The major crop growing season is therefore confined to periods of the long rainy season (weeks 22nd to 39th, or 28th May–30th September). The water balance for the study area indicates that the moisture availability index is greater than 0.5, and potential evapotranspiration is lower than precipitation during these months.ConclusionsClimate change and rainfall variability is creating a problem with crop production constraints in the rain-fed agricultural production system in the highlands of Ethiopia. Physical properties of the soil coupled with the unfavorable soil-rainfall relationship limit increased crop production on vertisols. Improving the drainage system and capturing rainfall variability in agronomic-relevant terms is essential. Improving the physical limitations of the soil, adapting to rainfall variability, and practicing improved agronomic practices may help farmers overcome the production problem. This study provides critical information on rainfall variability concerning vertisol management and crop production. However, to overcome the problem, technological support is needed from researchers and policymakers.

Temporal Rainfall Anomaly and Its Association with Crop Yield: In the Case of Afar Region, Ethiopia

Ethiopian economy is predominantly agrarian and the majority of the population in the country engaged in agricultural activities which is considerably affected by rainfall variability. The majority of the nation's crops are rain-fed, making them particularly vulnerable to the fluctuation that can cause severe food insecurity, which can result in famine and poverty over the whole nation. The impact of rainfall variability was very serious in the pastoral areas that are largely inhabited by the pastoralist whose livelihood depend primarily on livestock farming. For this study, rainfall data were taken from Ethiopian Meteorology Institute (EMI) for 1981-2020 period and yield data were taken from Central Statistical Agency (CSA) of Ethiopia for 1994-2019 period. This study was briefly evaluated rainfall variability and its impact on yield and computed Rainfall Anomaly Index (RAI) for Kiremt cropping season in a pastoral area of Afar region, Ethiopia. Regression analysis for the Kiremt cropping season based on observed rainfall dataset was used in the study to further analyze the relationship between rainfall variability and yield. The temporal analysis of RAI clearly indicated that there were more dry years than wet years with varies magnitude. The year of 1984 and 2009 were found extremely dry with magnitude of -4.95 and -4.13, respectively whereas 1987, 2015, 2002, 2004 and 1997 were identified as very dry with magnitude of -3.92, -3.39, -3.16, -2.88 and -2.41, respectively. The year of 1988 and 1998 found extremely humid with magnitude of 5.87 and 5.33 whereas 2020, 1994, 2010 and 1992 were very humid with magnitude of 3.47, 3.20, 2.98 and 2.34 respectively. The outcome of the regression analysis showed a positive link between rainfall anomaly and crop production for the Kiremt cropping season, with yield increasing with a positive rainfall anomaly and rainfall anomaly accounting for 29.4% of crop yield. Keywords: Kiremt Cropping Season, Rainfall Anomaly Index, Pastoral Area, Regression, Yield DOI: 10.7176/JEES/12-9-03 Publication date: September 30 th 2022

Impact of Rainfall Variability on the Streamflow of the Kara River Basin, Northern Togo

Water resources are affected by hydrological and climatological reactions in the Kara river Basin. The aim of this work is to analyze the dynamics of rainfall variability on the flow of the Kara River. Data was collected through documentary research and field surveys carried out among 82 correspondents. Data from the hydrological and climatological records (1955-2015) as well as socio-anthropological were used to conduct this research. The results were ascertained through state-pressure-impact-response model (SPIR). Year to year rainfall trends (1963 -2003) related to the stream flow showed that there has been low rainfall since the 1980s. This situation leads to extreme harsh flows of the Kara River located in the Kozah district. A look into the seasonal flow variability (1955-2015) showed that the average monthly flow figures over the years are very low from October to July (09 months) especially after the 1970s. This hydroclimatic dynamics have impacted the availability of water resources in the Kara basin located in the Kozah district. Indeed, the results of the annual changes in rainfall in relation to the flows of the Kara River showed a decrease in rainfall conditions from 1963 to 2003. As a result, people develop coping strategies that are ineffective.

Impact of rainfall variability and land-use changes on river discharge in Sanaga catchment (forest–savannah transition zone in Central Africa)

Abstract Climate change/variability and land-use changes are the main forcings of river discharges variability. However, an understanding of their simultaneous impacts on river discharges remains limited in some parts of the world like in Central Africa. To shed light on this issue, the objective of this article was to investigate the effects of rainfall variability and land-use changes on river discharges in the Sanaga watershed (at Song Mbengue and Nachtigal gauging stations) and some of its sub-watersheds (Mbakaou, Lom Pangar, Magba and Bamendjing) over the 5 or 7 recent decades (depending on the data availability). To achieve this goal, hydrometeorological data of the Sanaga watershed and sub-watersheds were analyzed using the Pettitt and Mann-Kendall tests. Likewise, land-use changes in the watershed and sub-watersheds were also analyzed using supervised classifications of Landsat satellite images of the watersheds at two periods (1984 and 2020). The results show that annual rainfall decreased throughout the Sanaga watershed. This decrease is only statistically significant for the Sanaga watershed at Nachtigal (−5%), for which the study focused on relatively longer hydropluviometric series, including the 1950 and 1960s (wet decades). However, although the rainfall decreased in this watershed, the flows increased insignificantly according to the tests used in most cases. The 2010s seems particularly concerned by this increase, including in the Sanaga watershed at Nachtigal, where the general trend is downward. The flows increase in the Sanaga watershed would be the consequence of the increase in impervious areas in the latter (between +181.3 and +1,300% for built and roads and between +4.1 and +11.9% for bare soils), which would compensate for the drop in precipitation by increasing runoff. These results could be used for long-term planning of water demand and use in this watershed, as well as for improving future simulations of flows.

Impact of Rainfall Variability and Land Use Change on River Discharge in South Cameroon

Climate change, variability and anthropogenic forcings such as land use change are the main forcings of river discharge variability. However, an understanding of their simultaneous impacts on river discharge remains limited in some parts of the world. To shed light on this issue, the objective of this article is to investigate the effects of rainfall variability and land use change on river discharge in the Nyong basin (at Olama and Mbalmayo gauging stations) and some of its sub-basins (So’o and Mefou) over the long period 1950–2018. To achieve this goal, hydro-meteorological data of the Nyong basin and sub-basins were analyzed using the Pettitt test. Likewise, land use changes in the basin and sub-basins were also analyzed using supervised classifications of Landsat satellite images of the basins at different periods (1973, 2000 and 2018). On the annual scale, rainfall has decreased statistically over the studied basins. In the large basins (Olama and Mbalmayo), this decrease in rainfall is synchronous with that of discharges, while it is concomitant with an increase in the Mefou (small basin). After the ruptures within time series identified in the annual modules, the extreme discharges (maximum and minimum) decreased in Olama; in Mbalmayo, the maximum discharges remained stable while the minimum discharges decreased. On the other hand, the maximum and minimum discharges have significantly increased in the Mefou. The stability of maximum discharges at Mbalmayo and the increase in extremes on the Mefou in a context where the precipitation that generates the discharge has decreased can be attributed to land use change. These changes are essentially marked by an increase in impervious areas and a reduction in forest cover. On the seasonal scale, the impact of precipitation in the dry season is visible on the flows of the rainy seasons that follow them on the large basins (Olama and Mbalmayo). Between the decades 1970–1990 and 2000–2010, there was respectively a significant increase, then a decrease in summer precipitation, which impacted the autumn discharges in the same direction. Conversely, between the same intervals, there was a significant decrease, then a slight increase in winter precipitation. The impact of winter precipitation on the spring discharge is more visible during the first period only (1970–1990). During the second period, winter precipitation seems to have more of an impact on the runoff for the same season. In the Mefou sub-basin, the precipitation plays an essentially amplifying role in the increase in discharge in the seasons during which they occur. Those having experienced an increase, or a maintenance of precipitation (summer and spring) recorded the most significant increases in discharges. These results could be useful for long-term planning on the demand and use of water, as well as flood management in the basins

Impact of Rainfall Variability on Maize Production in the NDOP Plain, North West Region of Cameroon (1990-2015)

This study assesses the impact of rainfall patterns from 1990-2015 on maize production in the NDOP Plain of the Bamenda Highlands of Cameroon since maize is a staple food and cash crop in the area. Data on rainfall and maize output were collected from 1990 to 2015 and represented in time series. The rainfall data were further analysed using Rainfall Anomaly Index (RAI), to establish critical periods of rainfall deficiencies. Results indicate that rainfall and maize production trends were increasing from 146.94 mm/month in 1990 to 220.03 mm/month in 2015 and ~0.28 tons/ha in 1990 to ~4.2 tons/ha in 2015 respectively. With uncertainties on the future of the rainfall pattern, the coefficient of variation was 22.03% (unreliable), and farmers should build resilience through agroecology, climate-smart agriculture, conservation agriculture and diversification of production systems.

Assessing the impacts of inter-annual rainfall variability on cash crops’ yield in Ondo state, Nigeria

The agriculture sector is of great importance to the development of any nation in Africa; hence, it is determined by the operating climatic mechanisms of such nation, especially rainfall. This study was carried out to assess the inter-annual rainfall variability impacts on cash crop yield in Ondo state for a period of twenty years (2000-2019). The study employed mainly secondary data which was analyzed using inferential statistics. Trend analysis was used to determine the pattern of rainfall and cash crops’ yield for the period under review. Also it was revealed that there were fluctuations in the trend of rainfall and the yield of cash crops. The correlation analysis showed a significant relationship between rainfall and cash crops yield; but an inverse relationship with rubber yield specifically. On the other hand the regression analysis showed little impact of rainfall variability on cash crop yield. However, it was recommended that in this era of dwindling economy due to over reliance on crude oil in Nigeria, the government through National Orientation Agency and Non-governmental Organizations should keep persuading and enlightening Nigerians to venture into agriculture to save the country’s economy and reduce poverty. Â

Impact of rainfall variability on crop yields and its relationship with sea surface temperature in northern Ethiopian Highlands

Knowing the spatial and temporal variation of rainfall is crucial for the management of agricultural productivity. This study aimed at evaluating rainfall variability impact on crop yields and its relationship with sea surface temperature using GIS and statistical techniques in North and South Wello zones, northern Ethiopian Highlands. In this study, 30 years (1984–2013) time series data of rainfall from National Centers for Environmental Prediction’s Climate Forecast System Reanalysis and National Meteorological Agency, sea surface temperature from National Oceanic and Atmospheric Administration, and crop data from Central Statistical Agency were used. With regard to spatial and temporal distribution of rainfall, the highest amount of mean total Kiremt/summer and annual rainfall was 993.71 mm and 1715.95 mm, respectively. The magnitude of mean total Kiremt and annual rainfall temporal and spatial variations, using percentage of coefficient variation, was ranging from 24.8 to 62% and from 23.13 to 57.86%, respectively. The correlation between total Kiremt and Belg rainfall with mean sea surface temperature was negative (r = −0.457) and positive (r = 0.385), respectively and statically significant at alpha 0.05 level. From the regression analysis, it was observed that the variation of crop production was explained by the variation of rainfall. For instance, the impact of mean Kiremt rainfall accounted for 47.5% (R2 = 0.475) of variations in sorghum. Generally, the analysis of this study revealed that rainfall variability is one of the major determinant factors for variation of major crop yields in the study area, and this information might be used as an input for decision-makers take appropriate adaptive measures in various agricultural and water resource sectors. For instance, this study recommends the expansion of irrigation and water management practice and promoting perennial trees like fruits and drought-resistant crops.

The Impact of Rainfall Variability on Diets and Undernutrition of Young Children in Rural Burkina Faso.

Background: Climate change and consequent increases in rainfall variability may have negative consequences for the food production of subsistence farmers in West Africa with adverse impacts on nutrition and health. We explored the pathway from rainfall through diet up to child undernutrition for rural Burkina Faso.Methods: The study used data of a dynamic cohort with 1,439 children aged 7–60 months from the Nouna Health and Demographic Surveillance Site (HDSS) for 2017 to 2019. We assessed data on diets, height, weight, household characteristics, and daily precipitation (from 1981 to 2019). Principal component analysis was used to identify distinct child dietary patterns (Dietary Pattern Scores, DPS). These were related to 15 rainfall indicators by area to obtain a precipitation variability score (PVS) through reduced rank regression (RRR). Associations between the PVS and anthropometric measures, height-for-age (HAZ), and weight-for-height (WHZ), were examined using multi-level regression analysis.Results: Stunting (HAZ < −2) and wasting (WHZ < −2) were seen in 24 and 6% of the children. Three main dietary patterns were identified (market-based, vegetable-based, and legume-based diets) and showed mixed evidence for associations with child undernutrition. The RRR-derived PVS explained 14% of the total variance in these DPS. The PVS was characterized by more consecutive dry days during the rainy season, higher cumulative rainfall in July and more extremely wet days. A 1-point increase in the PVS was associated with a reduction of 0.029 (95% CI: −0.06, 0.00, p < 0.05) in HAZ in the unadjusted, and an increase by 0.032 (95% CI: 0.01, 0.06, p < 0.05) in WHZ in the fully adjusted model.Conclusion: Rainfall variability was associated with dietary patterns in young children of a rural population of Burkina Faso. Increased rainfall variability was associated with an increase in chronic undernutrition, but not in acute undernutrition among young children.

Impact of Rainfall Variability on Rural Tea Roads in Kericho, Kenya

Climate variability is a global phenomenon that is posing a threat to the infrastructure and agricultural sector. Intense precipitation often results in the deterioration of rural road infrastructure resulting in inaccessibility. Rainfall and temperature data from 1989 to 2019 was obtained from Kenya Meteorological Department. Data on Greenleaf and cost of repairs and maintenances are from selected tea factories managed by Kenya Tea Development Agency. Data on perception is based on a questionnaire survey of 398 randomly selected tea farmers. Results show that climate variability is experienced in Kericho (p &lt; 0.005). There is a varsity variation in mean maximum temperatures F(0.05, 29) ꞊ 5.564 (p ꞊ 0.009) and mean minimum temperature F(29) =8.503 (p ꞊ 0.000). However, the linear regression analysis shows that rainfall has decreased (y ꞊ 2.5476x - 40.778) while the temperature has increased (y ꞊ 0.028x - 0.4473). There is a significant positive correlation between the amount of rainfall and cost of repairs and maintenances for five factories (r ꞊ 0.122, r = 0.046, r = 0.029, r = 0.255) except one (r = -.261, p ꞊ .466). Therefore, the climate has significantly varied from 1989-2019 and heavy rains occur periodically that damage rural tea roads, thus impacting negatively on tea transportation. There is a need, therefore, for heavy investment of emergency funds for repair and maintenance of rural tea roads based on rainfall variability and heavy rain return period pattern.

Impact of rainfall variability on maize yield in the KwaZulu-Natal, North-West and Free State provinces of South Africa (1987–2017)

Climate change has increased temperature, caused drought in places like North West Province, and reduced crop yield. This study investigated the climate change impact (rainfall) on maize yield (1987 -2017). The objectives were to determine the climate change impact on maize yield for Kwazulu-Natal, North West, and Free State Provinces of South Africa, assess the difference in climate change impact on maize yield between the three provinces. Rainfall and maize data were collected from WeatherSA and DAFF, respectively. A Pearson Correlation Analysis revealed a weak negative correlation between rainfall and maize for KwaZulu-Natal and Free State Provinces. However, for North West Province there was a weak positive correlation between maize yield and rainfall. Rainfall determines yield, if excessive, it becomes detrimental to crop yield. Climate change affected negatively on maize yield, rainfall above maize requirement was not beneficial to crop yield and drought reduced yield too. ANOVA results revealed that the group mean yield between the Provinces was different, with KwaZulu-Natal having the highest mean yield. The climate change impact on maize varied between provinces, KwaZulu-Natal Province was least affected, however, North West Province was the most negatively impacted with drought events leading to reduced maize yield.

Parameterization of river incision models requires accounting for environmental heterogeneity: insights from the tropical Andes

Abstract. Landscape evolution models can be used to assess the impact of rainfall variability on bedrock river incision over millennial timescales. However, isolating the role of rainfall variability remains difficult in natural environments, in part because environmental controls on river incision such as lithological heterogeneity are poorly constrained. In this study, we explore spatial differences in the rate of bedrock river incision in the Ecuadorian Andes using three different stream power models. A pronounced rainfall gradient due to orographic precipitation and high lithological heterogeneity enable us to explore the relative roles of these controls. First, we use an area-based stream power model to scrutinize the role of lithological heterogeneity in river incision rates. We show that lithological heterogeneity is key to predicting the spatial patterns of incision rates. Accounting for lithological heterogeneity reveals a nonlinear relationship between river steepness, a proxy for river incision, and denudation rates derived from cosmogenic radionuclide (CRNs). Second, we explore this nonlinearity using runoff-based and stochastic-threshold stream power models, combined with a hydrological dataset, to calculate spatial and temporal runoff variability. Statistical modeling suggests that the nonlinear relationship between river steepness and denudation rates can be attributed to a spatial runoff gradient and incision thresholds. Our findings have two main implications for the overall interpretation of CRN-derived denudation rates and the use of river incision models: (i) applying sophisticated stream power models to explain denudation rates at the landscape scale is only relevant when accounting for the confounding role of environmental factors such as lithology, and (ii) spatial patterns in runoff due to orographic precipitation in combination with incision thresholds explain part of the nonlinearity between river steepness and CRN-derived denudation rates. Our methodology can be used as a framework to study the coupling between river incision, lithological heterogeneity and climate at regional to continental scales.

Impact of rainfall variability on the ecophysiology of Hyptis suaveolens: a study in the constructed tropical grassland.

Hyptis suaveolens is considered one of the most potent invaders in the eastern part of Uttar Pradesh, India. Climate change especially precipitation variability along with invasion has enormous consequences. To understand how an invasive plant (H. suaveolens) performs and interacts with precipitation variability, particularly in tropical monsoon climate, is vital. To assess the above, three rainout shelters with simulated rainfall of 1600mm (60% more rainfall than ambient), 1100mm (average rainfall) and 800mm (20% less rainfall than ambient) along with one unsheltered plot (open C) were established. Three invaded grassland (IG) and three uninvaded grasslands (NIG) patches of 1 × 1m2 size were established randomly in each sheltered and unsheltered plot. Among the studied physiological properties and growth measurements, photosynthetic rate, height, diameter and biomass varied significantly with precipitation, in general, the maximum value of these in plots receiving maximum precipitation. Also, the aboveground biomass of H. suaveolens was found to be more sensitive towards precipitation treatment than belowground biomass. H. suaveolens biomass was linearly related to soil moisture (R2 = 0.73), and a linear combination of SM and soil pH increased the R2 value by 19%. The results indicate that H. suaveolens mediates certain soil properties especially related to N-mineralisation, to maintain a constant supply of nutrient, for faster growth under the favourable condition of enhanced precipitation. These findings suggest that the population of H. suaveolens has not evolved drought tolerance, so it is likely that H. suaveolens will not spread in the part of the world which is drier either naturally or due to climate change.

Impacts of rainfall variability on paddy production: A case from Bayawa minor irrigation tank in Sri Lanka

Rainfall (RF) variability has been suggested as the primary reason for low paddy production in the recent past under minor irrigation tanks (MITs). A study was conducted to verify the relationship between observed crop success/failures and the RF variability in the Bayawa MIT system in the Kurunegala district of Sri Lanka. Seasonal and annual RF variability and its effect on paddy crops were analyzed. Daily rainfall data were obtained from the Wariyapola station from 1983 to 2014. Paddy production data for 20 consecutive seasons from 2003 to 2014 were collected from the Department of Census and Statistics (DCS), Colombo. Paddy samples from the Bayawa command area were used to calculate the land productivity and compared between the two cultivation seasons. Three types of direct RF impacts on paddy production in the Bayawa MIT system were identified: (1) reductions in the cropping intensity (CI), (2) total crop failures and (3) reductions in yield. During the study period, the CI was 80–173% with an average of 140% (expected value is 200%). Sixty percent of annual and seasonal RF values were below the long-term average showing a direct effect of RF on crop failures. Low production is not only due to the variability of annual or seasonal RF during the cultivation seasons, but also due to poor water management decisions, such as not cultivating considering the available water in the MIT. Thus, there is a need for wise water management decisions of MITs in this study area based on the variability of RF for sustainable paddy production.

Impact of Smart Valley on Soil Moisture Content and Rice Yield in Some Lowlands in Burkina Faso

To reduce the impact of rainfall variability on lowland rice yields, Burkina Faso state develops lowlands for small rice farmers. However, the high cost of these infrastructures makes impossible to duplicate them to satisfy the needs which are enormous. The Smart-Valley technology which is actually popularized in certain coastal countries of West Africa would therefore be a boon to increase the productivity of the Sudanese lowlands if it well regulates runoff. The object of this study was therefore to know if smart valley technology could increase soil moisture in order to mitigate the impact of drought’s pockets on rice cultivation in the Sudanese lowlands. The experiment takes place in three lowlands during the rainy seasons 2018 and 2019. The climatic data comes from the meteorological stations in the study areas as well as those installed on the sites. The infiltration measurements were carried out using the double Muntz ring. The soil moisture measurement device consisted of a smart valley area of 5 ha and an undeveloped area of 5 ha per site. Sixteen tubes were installed per lowland allowing the humidity to be measured at a depth of 10, 20, 30, 40 cm using a probe. Four rice varieties, Orylux6, FKR62N, FKR19 and FKR64 were tested on plots of 0.25 ha per variety in the smart valley and undeveloped parts. The results showed that the humidity level was 12% higher in the smart-valley plots throughout the cycle compared to the unmanaged area. In addition, humidity decreases rapidly in unmanaged plots as rain becomes increasingly scarce. Finally, the smart-valley development allowed an average increase in rice yields of 21% compared to the average yield of undeveloped plots.

Rainfall Variability and Food Crop Vulnerability in Ndu Sub-Division, North West Region of Cameroon

Little scientific evidence exists in the context of climate variability and food crop production in Ndu. This study seeks to assess the impact of rainfall variability on food crop vulnerability in Ndu Sub-Division. The primary data were gotten through field surveys. A total of 200 farmers were sampled and questionnaires were administered to them. Descriptive and inferential statistical techniques were employed to analyze the data. Results were presented in tables and climographs. Formulated hypotheses were tested using the least square regression model to establish the extent of exposure and sensitivity of rainfall variability on food crop production. The Pearson Product Moment Correlation Coefficient was used to describe the trends of variations in rainfall. Statistically, rainfall accounted for 19.5% of variability in maize production while 50.87% accounted for variability in beans production. Furthermore, 30.1% accounted for variations in potatoes production. From these statistics it was then concluded that rainfall variability minimally affects maize and beans but had a significant effect on maize production in Ndu. The research study also revealed that rainfall shows a decreasing trend. The study recommended, amongst others the need for farmers to adopt more sustainable agricultural practices and the increased use of more resistant crop species that can withstand exposure and sensitivity to rainfall variability. The study concluded that a bottom-up approach should be employed in order to improve on the adaptive capacities of the agricultural sector in Ndu.

Impact of rainfall variability and anthropogenic activities on streamflow changes and water stress conditions across Tapi Basin in India

Water security is a major concern in recent years, especially, in semi-arid and arid regions, which are adversely impacted due to extensive anthropogenic and climatic changes across the globe. Present study investigates the long-term changes in streamflows, their quantitative attribution and socio-environmental implications for a climatically sensitive Tapi basin in west central India. The abrupt and gradual changes in streamflows have been detected over the period 1973–2013 using non-parametric Pettit's and Mann-Whitney U tests; and Modified Mann-Kendall, Spearman's Rho and Sen's slope estimator tests respectively. The streamflow analyses revealed heterogeneity across the basin, wherein the tributaries exhibited higher variability in annual runoff compared to the Tapi River. The spatial analyst tool of ArcGIS has been used to graphically demonstrate the spatial variability in rainfall and streamflow trends across the basin. The streamflows exhibited predominantly decreasing trends across the basin, except in the upper reaches of the Tapi River. The decreasing trends in streamflow are largely attributed to anthropogenic activities such as changes in the land use patterns viz., increase in agriculture area, construction of minor and medium hydraulic structures, decrease in forest cover, rapid urbanization, excessive groundwater extraction and streamflow regulations. The anthropogenic activities played a major role in declining streamflow trends in the Tapi basin, contributing about 68%–99% (average 85%) decline in total runoff, compared to rainfall variability, which contributed around 1%–32% (average 15%) decrease in total runoff. The analysis of water stress levels at sub-catchment scale exhibited significant rise in percentage of population living in the basin facing chronic water shortage (i.e., <1000 m3/capita/year), from 34.0% in year 1981 to 63.2% in year 2011, mostly in semi-arid regions. The reduction in water availability clearly highlighted the deteriorating water quality and stream ecology of the Lower Tapi River in Surat city, India.

Impact of Rainfall Variability on Crop Production within the Worobong Ecological Area of Fanteakwa District, Ghana

Crop production in the Fanteakwa District is predominantly rainfed, exposing this major livelihood activity to the variability or change in rainfall pattern. The net potential effect of severe changes in rainfall pattern is the disruption in crop production leading to food insecurity, joblessness, and poverty. As a major concern to food production in Ghana, this study seeks to show the relationship between the production of major crops and rainfall distribution pattern in the Worobong Agroecological Area (WAA) relative to food security in the face of climate change. The study analysed the variability in local rainfall data, examining the interseasonal (main and minor) rainfall distribution using the precipitation concentration index (PCI), and determined the pattern, availability of water, and the strength of correlation with crop production in the WAA. Data from the Ghana Meteorological Agency (GMet) spanning a 30-year period and grouped into 3 decades of 10 years each was used. Selected crop data for 1993-2014 was also obtained from the Ministry of Food and Agriculture’s District office and analyzed for trends in crop yield over the period and established relationship between the crop data and the rainfall data. Part of the result revealed that rainfall variability within the major seasons in the 3 groups was lower than the minor seasons. It further showed that yields of three crops have declined over the period. Among the strategies to sustain crop production is to make the findings serve as useful reference to inform discussions and policy on adaptive agricultural production methodologies for the area in the face of changing climate.