Decrease In Annual Rainfall Research Articles

Spatio-temporal distribution of Vachellia stuhlmannii (Taub.) in Venetia-Limpopo nature reserve – SPOT-imagery

The impact of African elephant (Loxodonta africana) on selected woody plants varies from local extirpation to persistence amid continuous utilisation. Species generally selected by elephants and the way they are foraged makes them vulnerable to high utilisation levels. This paper studied the spatial and temporal distribution of Vachellia stuhlmannii in Venetia-Limpopo Nature Reserve using SPOT ( S ytéme Pour l’Observation de la Terre) imagery. The spatial pattern distribution of the species was computed using the Spatial Point Pattern Analysis (SPPA) and the Complete Spatial Randomness (CSR) of the species was tested using the Nearest Neighbour Ripley’s K(r) function. Results indicate a significant decrease in the area covered by V. stuhlmannii between 2013 and 2017, with a subsequent decrease in the density of the species. This result was positively correlated (Pearson correlation r 3 = 0.796, P = 0.634) to a decrease in annual rainfall. V. stuhlmannii follows an aggregated spatial pattern, which led to the rejection of the null hypothesis (H o) test of complete spatial randomness. Limitation of this study is that the results are based on five-year data between 2013 and 2017. This was influenced by the SPOT data used that is made available commercially. It is recommended that further studies evaluate the species distribution and density prior to 2013 to determine whether the decrease is because of other browsers, diseases, elephant impact, decreasing annual rainfall or combination of factors.

Spatiotemporal characterization of the annual rainfall variability in the Isser Watershed (Algeria)

Wadi Isser watershed (4149 km2), located in the North of Algeria, has experienced a significant rainfall variability during the last four decades. In order to characterize this variability and determine its spatial extension, by means of the analysis of the rainfall data measured in twenty-seven (27) stations, the following study was conducted. The analysis of the long rainfall series of the reference stations of Bni Slimane (1920–2014) and Djebahia (1923–2014) through the application of three statistical tests (Pettitt, Buishand and Lee and Heghinian) revealed an episode of low rainfall from 1973 to 2001 for the Djebahia station and from 1975 to 2001 for the Bni Slimane station. This period was characterized by a decrease in annual rainfall varying between 14 and 43%, followed by a rainy phase in the watershed with an increase in annual rainfall (35.8%) at the Khebouzia station. The analysis of the kriged maps, developed by geostatistical modeling of the spatial structure of precipitation (1975–2014), supported and corroborated the results of the statistical tests. Indeed, the spatial interpolation based on decadal averages of rainfall from 1975 to 2014 illustrates a well-contrasted spatial variability for the four decades. The northern part of the watershed is characterized by a higher rainfall than the central and southern parts of the watershed. In the light of the results obtained by applying the two approaches mentioned above, a decreasing trend in rainfall is clearly evident from the beginning of the decade 1985–1994. A double rainfall gradient is highlighted with an increase in rainfall from east to west and from north to south. At the same time, there was a surplus towards the end of the third decade and the fourth decade. A return of precipitation is thus highlighted as well as the different breaks in the series. Through this research, the statistical study and the geostatistical mapping have enabled the elaboration of a relevant tool for decision support to the managers in the field of environment and hydraulics, in a general way, and in a context of global warming. In fact, it will allow them to better understand the developments of wadis, the integrated management of water resources in order to guarantee current and future needs for drinking, industrial, and agricultural water in this semi-arid region.

Analysis of average annual temperatures and rainfall in southern region of the state of Rio Grande do Sul, Brazil

This work aimed to analyze the average temperature and rainfall in the Southern and Steppe regions of the State of Rio Grande do Sul, Brazil, obtained by three global climate models regionalized by the Eta model (CANESM2, HADGEM2-ES and MIROC5) for the historical period, and two future climate scenarios (RCP 4.5 and RCP 8.5), subdivided into three periods: F1 (2006-2040), F2 (2041-2070), and F3 (2071-2099). The analysis was conducted by applying the trend tests Mann Kendall’s, Sen’s Slope and Pettitt’s to the dataset. The study noted an increase in temperature, and that the highest temperatures will occur at the end of the century. For the three climate models, temperatures will be milder in the RCP 4.5 scenario, mostly, when compared to the RCP 8.5. For those scenarios, a significant increase up to 0.95°C/year was observed in the temperature of all series, with the years of change in the mean values occurring between 2048 and 2060. The projections also suggest that there may be an increase in the average accumulated rainfall in the future periods analyzed, with exception of the result found with CANESM2 model at the RCP 8.5 scenario, which showed a significant decrease of annual rainfall in all series, ranging approximately from -3,1 to -6,6 mm/year. Those significant changes in mean of the rainfall series are expected for the late 2070's. With exception of this result, most cities and models indicate an increase in rainfall regimes, with clear variations between models and scenarios.

Effect of climate variability on yields of selected staple food crops in northern Ghana

Agriculture in Ghana is vulnerable to the adverse effects of climate variability. This poses a challenge to food security across the country. Despite this vulnerability, limited research has been conducted to understand the effect of climate variability on the yields of staple food crops in Ghana. This study assessed the effect of climate variability on the yields of selected staple food crops (millet, sorghum, rice, groundnut and maize). The study used the Mann-Kendall trend test and multiple regression analysis to assess how climate variability (in annual rainfall, onset, cessation, number of dry days and temperature) has affected the yields of selected food crops in five districts in northern Ghana (Bole, Nanton, Tolon, Kassena Nankana East and Wa) over a 21-year period (1995–2016). Results suggested a marginal decrease in annual rainfall ( p > 0.05) and a significant increase in temperature ( p < 0.05) over the period of study in the districts. Variability in the onset, cessation, length of rainy days and number of dry days was statistically significant from year to year, and also across the districts ( p < 0.05). Results indicated substantial variability in the yields of the selected staple food crops. Temperature, number of dry days, onset, annual rainfall and cessation explained about 43%, 32%, 30%, 25% and 14%, respectively of the variations in the yields of groundnut, sorghum, millet, maize and rice. Our results generally suggest that the changing climate substantially affects food production in the study districts, highlighting the need for adaptations including the use of agricultural diversification and the greater use of drought tolerant varieties of these staple crops, as well as the continuing investment in crop breeding programmes to enhance drought tolerance. • Climatic variables (annual rainfall, onset, cessation, number of dry days and temperature) are erratic in northern Ghana. • Changing climate substantially affects food production in northern Ghana. • Continuing investment in crop breeding programmes to enhance drought tolerance.

Risk and Resilience of Somali Children in the Context of Climate Change, Famine, and Conflict

Climate change is an existential threat to all of humanity. Its impact on the children of Somalia provides insights into the severity of risks posed by climate change to current and future generations. Globally, there has been a continuous increase in mean annual temperatures since 1991 and scientists anticipate an increase of up to 4.3 degrees Celsius by the end of the century. Concomitantly, Somalia has experienced a decrease in annual rainfall, resulting in recurrent droughts. According to the UN’s emergency aid coordination office, these droughts have grown in frequency and intensity over the past three decades, fueling increased frequency of famine and contributing to internal conflict and civil war. In this article, the impact of climate change on children, exemplified by the plight of Somali children, is viewed through the lens of cumulative adversity and related consequences of poverty on malnutrition, illness, disruptions of family systems, and displacement, with a diaspora around the globe. The paper promotes a multi-systems resilience framework that guides strategies for addressing the complex, cascading crises that accompany climate change, exploring the construct of resilience from the individual/interpersonal level through family systems and communities, including a reframing of the Somali diaspora. The paper concludes with a series of global transnational policy recommendations based on children’s rights, the promotion of resilience, and approaching climate change from a child sensitive perspective, encouraging youth engagement and leadership, along with peace-building.

Perception and adaptation of pastoralists to climate variability and change in Morocco's arid rangelands

Since the late 1970s, extensive livestock production in the high plateaus of Eastern Morocco, particularly of small ruminants, has been seriously threatened by climate change (CC). Negative impacts include reduction in rangeland forage production and water availability, increased poverty and inequality, and increased degradation of rangelands. Different categories of pastoralists have adopted different combinations of adaptation strategies, but the factors influencing adoption have not to date been investigated. This paper aims to identify the perceptions of pastoralists on CC, to analyze the adaptive responses of different wealth categories, and to determine the factors affecting the adoption of adaptation measures. The Mann-Kendall, Pettitt and Buishand tests and the standardized precipitation index were used to analyze the climate data. Data on adaptation were examined using the chi-square homogeneity test, Kruskal-Wallis test and binary logistic regression.The observed climate trends perfectly corroborated pastoralists' perceptions of significant changes in their local climate since the 1970s: a considerable decrease in annual rainfall and an increase in temperature and frequency of droughts and high winds. There were significant differences (Chi square = 7.603, p = 0.022, df = 2) between small, medium and large pastoralists in the frequency adoption of adaptation strategies, especially between small and large pastoralists (U statistic = 16.000, p = 0.009). The distribution of most adaptation actions also differed significantly between these two groups. Wealthier pastoralists have adopted a greater range of strategies, while poorer pastoralists have less diverse adaptation portfolios, and are more likely to adopt less advantageous strategies such as casual labor. The adoption of adaptation practices was significantly influenced by equipment, educational level, household size, herd size, training received, CC perceptions and agroecological setting. Public interventions to improve the adaptive capacity of pastoralists in Morocco's arid rangelands should be geared towards addressing these determinants and should prioritise small-scale pastoralists.

Annual Rainfall in Pernambuco, Brazil: Regionalities, Regimes, and Time Trends

Abstract This study aimed to identify the homogeneous zones, the regimes, and the local trends for annual and seasonal rainfall in the state of Pernambuco, Brazil. We collected seasonal and annual data on monthly rainfall from 45 weather stations in Pernambuco from 1987 to 2019. The data were organized yearly to identify the homogeneous rainfall zones based on Euclidean distance and Ward's coefficient. The mean annual value of each zone was calculated and the data were subjected to descriptive statistics analysis, analysis of rainfall regime with the Rain Anomaly Index, and time trend analysis using the Mann-Kendall method. The results show three homogeneous rainfall zones: 1 (semiarid), 2 (transition), and 3 (coastal), with mean values for annual rainfall of 562, 1032, and 1812 mm year-1, respectively. The precipitation regime showed the predominance of dry years as zones 1, 2, and 3 exhibited dry periods of 18, 17, and 15 years, respectively. Time trend analysis revealed a decrease in annual rainfall of 48.7 mm for Zone 1, 13.2 mm for Zone 2, and 204.4 mm for Zone 3, without statistical significance. Seasonal analysis demonstrated that Zone 1 presented a negative trend in the spring and a positive trend in Zone 2 in the summer, indicating changes in the rain seasonality.

Geochemical and isotopic evidence of groundwater salinization processes in the Essaouira region, north-west coast, Morocco

The city of Essaouira is located along the north-west coast of Morocco, where groundwater is the main source of drinking, domestic and agricultural water. In recent decades, the salinity of groundwater has increased, which is why geochemical techniques and environmental isotopes have been used to determine the main sources of groundwater recharge and salinization. The hydrochemical study shows that for the years 1995, 2007, 2016 and 2019, the chemical composition of groundwater in the study area consists of HCO3–Ca–Mg, Cl–Ca–Mg, SO4–Ca and Cl–Na chemical facies. The results show that from 1995 to 2019, electrical conductivity increased and that could be explained by a decrease in annual rainfall in relation to climate change and water–rock interaction processes. Geochemical and environmental isotope data show that the main geochemical mechanisms controlling the hydrochemical evolution of groundwater in the Cenomanian–Turonian aquifer are the water–rock interaction and the cation exchange process. The diagram of δ2H = 8 * δ18O + 10 shows that the isotopic contents are close or above to the Global Meteoric Water Line, which suggests that the aquifer is recharged by precipitation of Atlantic origin. In conclusion, groundwater withdrawal should be well controlled to prevent groundwater salinization and further intrusion of seawater due to the lack of annual groundwater recharge in the Essaouira region.

Spatio-temporal analysis of rainfall pattern in the Western Ghats region of India

This paper investigates the rainfall pattern and its distribution, which is one of the key drivers for the water availability in the Western Ghats region of India. The daily precipitation data from 1901 to 2014 were investigated to understand the rainfall pattern and its variability. The study area has been divided as southern, coastal, central, and northern regions and rainfall amount into 0.2–10 mm, 10–20 mm, and > 50 mm classes. The trends in the annual rainfall, number of rainy days, and various classes within these regions have been investigated. The mean annual rainfall varies between 4000 mm in the coastal areas and greater than 6000 mm at the mountain crest. The Mann–Kendall test indicates significant decrease of annual rainfall, at 5% significance level in central and coastal region. On Contrary, the coastal region recorded significant decrease in the number of rainy days at 5% significance level. An increasing trend in the number of rainy days has been observed in the northern region. No significant trends have been detected in the southern region. A decreasing trend has been detected in the number of rainy days in the rainfall class with 10–20 mm in coastal region. Similarly a significant decrease of rainy days was observed in > 50 mm rainfall class both in the southern and northern regions. The change point probability and homogeneity test indicates that there is a significant increase in rainfall in few stations under the northern region and similarly decrease in the rainfall in central region during the decade of 1970 and normally the rainfall has been homogeneous in the study area. From the precipitation concentration analysis found that Mysore, Kodagu, and adjoining areas are influenced by the bi-modal rainfall, receiving the rainfall during both south–west and north–east monsoons. This analysis helps to understand the spatial variability of rainfall in the Western Ghats of India, which depict mixed trends in the quantum of rainfall and decreasing trend of rainy days across various rainfall classes. These changes detected in the historical rainfall, both in its occurrence and quantum will have significant bearing on the water availability scenario in the Western Ghats region.

Mediterranean badlands: Their driving processes and climate change futures

AbstractBadlands are landforms that occur all over the World. In the Mediterranean region, badlands are found in both dry (arid and semi‐arid) and wet (subhumid and humid) environments, and are characterized by complex hydro‐geomorphological dynamics, high intense erosion processes and extreme sediment yield. Understanding the impact of Global Change is key to predict the on‐site and off‐site effects on badland dynamics, particularly its consequences on bedrock weathering, on sediment yield and delivery and on plant colonization. Here, conducting a systematic literature review, we analyzed an extensive database and identified the main climate‐drivers affecting the hydro‐geomorphological dynamics in Mediterranean badlands (based on non‐metric multidimensional scaling and structural equation modeling analysis). Later, we examined the main impacts expected from climate change forecasting in the near future, and we explored the interactions between badlands response to climate variation. In Mediterranean badlands, weathering processes are mainly related to wetting–drying cycles and freeze–thaw cycles in dry and wet badlands, respectively. In both environments, rainfall amount appears as the main driver for runoff response, and rainfall amount and rainfall intensity for erosion dynamics. Future climate scenarios forecast a decrease in annual rainfall, number of rainfall events and frost days, and in soil moisture, and an increase in rainfall intensity. These changes will have direct hydro‐geomorphological implications with direct and indirect effects on badland dynamics. This may result in a decrease in annual runoff in dry badlands, but the occurrence of more frequent extreme events would increase soil erosion and could negatively affect biological soil crust. In wet badlands, weathering and erosion processes may decrease, and a stabilization of the slopes, with consequently improved vegetation growth, may be expected. In addition, the forecasted changes must be taken into account, especially considering the possible off‐site effects of these extreme environments.

Modeling the response of soil moisture to climate variability in the Mediterranean region

Abstract. Future climate scenarios for the Mediterranean region indicate a possible decrease in annual precipitation associated with an intensification of extreme rainfall events in the coming years. A major challenge in this region is to evaluate the impacts of changing precipitation patterns on extreme hydrological events such as droughts and floods. For this, it is important to understand the impact of climate change on soil moisture since it is a proxy for agricultural droughts, and the antecedent soil moisture condition plays a key role on runoff generation. This study focuses on 10 sites, located in southern France, with available soil moisture, temperature, and precipitation observations for a 10-year time period. Soil moisture is simulated at each site at the hourly time step using a model of soil water content. The sensitivity of the simulated soil moisture to different changes in precipitation and temperature is evaluated by simulating the soil moisture response to temperature and precipitation scenarios generated using a delta change method for temperature and a stochastic model (the Neyman–Scott rectangular pulse model) for precipitation. Results show that soil moisture is more impacted by changes in precipitation intermittence than precipitation intensity and temperature. Overall, increased temperature and precipitation intensity associated with more intermittent precipitation leads to decreased soil moisture and an increase in the annual number of days with dry soil moisture conditions. In particular, a temperature increase of +4 ∘C combined with a decrease of annual rainfall between 10 % and 20 %, corresponding to the current available climate scenarios for the Mediterranean, lead to a lengthening of the drought period from June to October with an average of +28 d of soil moisture drought per year.

Impacts of Climate Variability on Sustainable Agriculture in Imo State, Nigeria

Rainfall and Temperature are important factors in agriculture especially in Nigeria where rain-fed agriculture is practiced extensively and agriculture contributes to food security and provides employment for urban and rural dwellers. Therefore, climate variability represents a major danger to agriculture by modifying the rainfall and temperature pattern, thereby resulting to a big peril in the sustainability of agriculture. This is the reason all countries of the world are concerned about the effects of climate variability on agriculture. This work therefore, examined the impact of climate variability on rainfall and temperature in Imo State, South Eastern Nigeria. The rainfall and temperature data were gotten from Nigerian Meteorological Agency (NIMET) for a period of 30 years which was analyzed by using descriptive statistics, decadal distribution, trend graph anomalies and 5 year moving average. The analysis showed increasing trend pattern in yearly maximum, minimum temperature and decrease in annual rainfall, The third order polynomial trend shows a decrease in the anomaly of annual mean rainfall (y = -0.0002x4) and a persistent increase in the mean temperature anomaly especially in the second decade (1996-2007).The discoveries show that there is a notable variability in temperature and rainfall pattern which revealed an increase in temperature and decrease in annual rainfall. This calls for serious attention as people in this part of Nigeria critically depend on rainfall for agricultural practices.It is recommended that government should support the agricultural sector by providing mechanized farming systems such as irrigation and drilling of water borehole in farm sites for agriculture, especially for the rural farmers and create awareness to the farmers on recent trends in climate issues to achieve sustainable agriculture.

Dynamics of land use and land cover changes in Huluka watershed of Oromia Regional State, Ethiopia

BackgroundLand use and land cover changes in urbanized watersheds of developing countries like Ethiopia are underpinned by the complex interaction of different actors, driving forces, and the land itself. Land conversion due to residential development, economic growth, and transportation is identified as the most serious environmental pressure on urbanized landscapes of the world. It results in the degradation of natural vegetation and significant increases in impervious surfaces. The purpose of the study was to analyze spatio-teporal changes in land use and land cover in the Huluka watershed with implications to sustainable development in the watershed.ResultsForest land, cultivated land, urban built-up, bush/shrub land, bare land, grassland, and water body were identified as the seven types of land use and land cover in the Huluka watershed. Forest land decreased by 59.3% at an average rate of 164.52 ha/year between 1979 and 2017. Bush/ shrub land decreased by 68.2% at an average rate of 318.71 ha/year between 1979 and 2017. Grassland decreased by 32.7% at an average rate of 228.65 ha/year between 1979 and 2017. Water body decreased by 5.1% at an average rate of 1.06 ha/year between 1979 and 2017. Urban built-up area increased by 351% at an average rate of 16.20 ha/year between 1979 and 2017. Cultivated land increased by 105.3% at an average rate of 692.76 ha/year between 1979 and 2017. Bare land increased by 41.9% at an average rate of 4.00 ha/year between 1979 and 2017. Infrastructural and agricultural expansion, increased demand for wood, local environmental and biophysical drivers, rapid human population growth, economic drivers, technological drivers, policy and institutional drivers, and local socio-cultural drivers were perceived by residents as drivers of land use and land cover changes. Increased flooding risk, increased soil erosion, increased sedimentation into water resources like lakes and rivers, decrease in soil fertility, loss of biodiversity, loss of springs, decrease in annual rainfall, and increase in heat during the dry season were perceived by residents as negative local effects of land use and land cover changes.ConclusionsChanges in land use and land cover in the study water shade imply the need for integrating sustainable watershed planning and management into natural resources management strategies. In other words, practices of appropriate land use planning and management, family planning, participatory planning and management, appropriate environmental impact assessment (EIA), and proper planning and management of development projects and programmes are of paramount importance to promote sustainable development in the Huluka watershed and beyond.

Quantification of pollutants in rainfall-runoff in plain areas with dense river networks: A case study in the Western Bank of Wangyu River, Taihu Basin

如何精细量化降雨径流污染负荷是流域尺度实现面源精准治污全过程控制的重要前提.本研究以水污染较为严重的望虞河西岸综合示范区为例，通过开展不同土地利用类型的降雨观测实验，修正SCS-CN模型中的初损率，并基于土地利用类型遥感解译和降雨径流污染物浓度测定，精细刻画降雨径流中总磷（TP）、总氮（TN）、氨氮（NH₃-N）、化学需氧量（COD）4类主要污染物的时空分布格局.结果表明：研究区绿地和农田、硬质地表的降雨初损率分别为0.3和0.9；径流深、污染负荷与降雨深之间存在显著的正相关性.随着降雨量逐年递减，研究区降雨径流中TP、TN、NH₃-N、COD四类污染物的负荷量分别从2017年的190、1359、445和16041 t减少至2019年的118、949、314和11250 t；单位面积TN和COD负荷最高的用地类型是农村住宅用地，草地的四种污染物单位面积负荷均最低，林地次之.相关研究结果为望虞河流域水污染控制提供了基础数据，也为定量测算平原河网区面源污染负荷提供了方法参考.;Quantifying the pollutant loads in rainfall-runoff plays a critical role in non-point water pollution control at the watershed level. In this study, rainfall-runoff experiments were conducted on various land use types in the western bank area of Wangyu River to localize the initial abstraction ratio in the SCS-CN model. Then, by incorporating the remote sensing interpretation of land use types and the measurement of pollutant concentration in the rainfall-runoff, this study explored the temporal and spatial patterns of four kinds of pollutants, namely total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH₃-N) and chemical oxygen demand (COD). The results indicate that the recommended initial abstraction ratios for grassland/forest/farmland and impervious surface in the study area are 0.3 and 0.9, respectively. Besides, the rainfall-runoff depths and pollutant loads are found to be significantly and positively correlated with the rainfall depths. Along with the decrease of annual rainfall in this region, the annual amount of TP, TN, NH₃-N and COD loads in rainfall-runoff have reduced from 190, 1359, 445 and 16041 t in 2017 to 118, 949, 314 and 11250 t in 2019, respectively. Rural resident land, among all the land use types, has the highest TN and COD loads per area, while grassland and forest rank the bottom. This study provides precise information about pollutants in rainfall-runoff to facilitate the development of water pollution control strategies in Wangyu River watershed and can be used as a methodological reference for future quantification of non-point source pollution practices in plain areas with dense river networks.

FACTORS OF DESTABILIZATION OF THE PHYTOSANITARY STATE OF AGROCENOSES OF GRAIN CROPS IN THE CENTRAL FOREST-STEPPE OF UKRAINE

Based on a comprehensive analysis of agrotechnical and environmental factors, the main factors of destabilization of phytosanitary condition of cereal crops are identified, which consist in high plowing of the Central Forest-Steppe, violation of scientifically sound structure of sown areas, cultivation of intensive and semi-intensive varieties. organisms, as well as a significant pesticide load. It is established that the structure of land in the Central Forest-Steppe is ecologically unbalanced with the ratio of arable land: hayfields and pastures: forests 1: 0.2: 0.1. The share of grain group crops in the structure of sown areas is over 52%, the main industrial crops — 32%. Among the crops of the grain group, the largest areas are occupied by corn, wheat and barley, and the crops of barley, oats and rye are decreasing. Significant changes in the structure of sown areas in 2004-2019 occurred due to an increase in the share of industrial crops — almost three times, cereals and legumes — by 6%. The seeds of most of the analyzed varieties of cereals are contaminated with phytopathogenic fungi of the genera Alternaria, Fusarium, Nigrospora, Bipolaris, Penicillium, Mucor, Epicoccum, Glicocladium, Drechslera with a high intensity of spore formation (up to 8 million units / ml), which is biologic. Among the environmental factors are changes in hydrothermal conditions, namely — increase in average annual air temperature by 1.8oC over the past 15 years, a decrease in annual rainfall by an average of 22% and changes in the distribution of precipitation in the middle of the year.

Climate Variability and Food Crop Production in Rural Cameroon: The Case of Ejagham Community - Manyu Division

This study set to establish the relationship between rainfall and temperature variabilities and food crop production in the Ejagham community, Cameroon. Data were collected for crop production in the area from 2006-2015, and for rainfall and temperature from 1975 – 2015. Variance means was used to analyse the trend in climatic conditions of rainfall and temperature while correlation coefficient was used to establish the relationship between climatic conditions and food crop production. Findings revealed that the trend in rainfall has been fluctuating. Clearly, rainfall dropped in the years 1986, 2001, 2003 and 2015. Overall, there has been a decrease in annual rainfall from about 3,000 mm in 1975 to almost 2,000 mm in 2015. The highest temperature was recorded in the 2010 with 29.0°C, followed by the year 2013 with 28.2°C. 2015 recorded the least temperature which had an average of 26.0°C. Furthermore, there exist a relationship between rainfall and temperature variabilities and food crop production in Ejagham area. This is indicated in the almost negative coefficients both for rainfall and temperature. It can therefore be concluded that there is a statistically significant relationship between rainfall and temperature variabilities and food crop production in Ejagham area.

Application of the SBAS-DInSAR technique for deformation monitoring in Tunis City and Mornag plain

The ground deformation phenomena are the result of the application of natural stress (tectonic) or anthropogenic stress (overexploitation of groundwater, embankment) on the soil. The land deformation may cause several impacts on the environment and human life. A good understanding of the deformation behaviour of the soil is essential to mitigate risks on the infrastructure and environment. In this study, a radar interferometry is carried out to analyse the mobility of an urban and suburban area of Greater Tunis region. The interferometric synthetic aperture radar (SAR) technique has been proven to be an effective methodology for detecting and monitoring soil displacement with millimetre accuracy and also, improving our understanding of the current deformations in the study area. Indeed, the application of differential SAR interferometry made it possible to determine the origin of the surface deformations related to natural or anthropic phenomena. In this paper, the interferometric method of small baseline subset (SBAS) developed by Berardino et al. 2002has been chosen, in order to monitor the spatial and temporal pattern of the deformation phenomena in Greater Tunis region. The analysis of Envisat ASAR (2003–2007, descending satellite orbit) and Sentinel 1B (2016–2018, ascending satellite orbit) SAR data allowed us to create deformation velocity maps associated with line of sight displacement time series. The results obtained by this method showed the existence of subsidence phenomenon in the urban areas (Tunis City) as well as in the rural areas (Mornag plain). In the first site (Tunis City), the subsidence rate reaches up to 13.98 mm/year and 19 mm/year during 2003–2007 and 2016–2018, respectively. The ground deformation that is detected around the region of Tunis Lake and Sebkhet Essijoumi, is probably due to the nature of the highly compressible and thickness alluvial deposits and whose substratum depth sometimes reaches more than 60 m. In the second studied site, ground subsidence was identified in the whole plain of Mornag. Indeed, the comparison between piezometric data and time series deformations shows that the trend of soil subsidence is coherent with the dynamic change in groundwater levels. Furthermore, the analysis of velocity deformation, geological data and hydrogeological information allows us to associate all the detected settlement patterns to groundwater overexploitation and compressible alluvium all over the plain. This overexploitation of groundwater in Mornag plain is mainly caused by the expansion of agricultural and industrial activities and the decrease in annual rainfall in recent years (from 2003 to 2018).

Changing climate - Changing livelihood: Smallholder's perceptions and adaption strategies

Experts expect that climate change will soon have a severe impact on the lives of farmers in the region surrounding Kerala, India. This region, which is known for its monsoon climate (which involves a distinct temporal and spatial variation in rainfall), has experienced a decrease in annual rainfall over the last century. This study is aimed at investigating how smallholder farmers perceive climate change and at identifying the methods that these smallholders use to adapt to climate change. We use data collected from a survey of 215 households to compare the climate vulnerability of three watershed communities in Kerala. We find that the farmers perceive substantial increases in both temperature and the unpredictability of monsoons; this is in accordance with actual observed weather trends. The selection of effective adaptation strategies is one of the key challenges that smallholders face as they seek to reduce their vulnerability. The surveyed households simultaneously use various adaptation methods, including information and communication technology, crop and farm diversification, social networking through cooperatives, and soil and water conservation measures. The results of a binary regression model reveal that the household head's age, education and gender, as well as the farm's size and the household's size, assets, livestock ownership, poverty status and use of extension services, are all significantly correlated with the households' choices regarding adaptations to cope with climate change.

Impact of future climate change on water supply and irrigation demand in a small mediterranean catchment. Case study: Nebhana dam system, Tunisia

AbstractThis study evaluates the impacts of climate change on water supply and demand of the Nebhana dam system. Future climate change scenarios were obtained from five general circulation models (GCMs) of CMIP5 under RCP 4.5 and 8.5 emission scenarios for the time periods, 2021–2040, 2041–2060 and 2061–2080. Statistical downscaling was applied using LARS-WG. The GR2M hydrological model was calibrated, validated and used as input to the WEAP model to assess future water availability. Expected crop growth cycle lengths were estimated using a growing degree days model. By means of the WEAP-MABIA method, projected crop and irrigation water requirements were estimated. Results show an average increase in annual ETo of 6.1% and a decrease in annual rainfall of 11.4%, leading to a 24% decrease in inflow. Also, crops' growing cycles will decrease from 5.4% for wheat to 31% for citrus trees. The same tendency is observed for ETc. Concerning irrigation requirement, variations are more moderated depending on RCPs and time periods, and is explained by rainfall and crop cycle duration variations. As for demand and supply, results currently show that supply does not meet the system demand. Climate change could worsen the situation unless better planning of water surface use is done.

Potential impacts of specific global warming levels on extreme rainfall events over southern Africa in CORDEX and NEX‐GDDP ensembles

AbstractThis study examines the potential impacts of specific global warming levels (GWLs) on extreme rainfall events in southern Africa and over 12 major cities in the region. We analysed two regional climate simulation datasets: the Coordinated Regional Climate Downscaling Experiment (CORDEX) and the NASA Earth eXchange Global Daily Downscaled Projections (NEX‐GDDP, hereafter referred to as NEX), which used different methods (dynamical and statistical, respectively) in downscaling several global climate model (GCM) simulations from CMIP5. Twenty simulations were used from each dataset. The simulated rainfall indices for the reference period (1971–2000) were compared with eight observation datasets. The projected changes in rainfall indices were examined at four GWLs under the RCP8.5 climate forcing scenario. The projections from the CORDEX and NEX ensembles were compared and the self‐organizing map (SOM) analysis was used to classify the projected changes from the simulations into 12 groups, based on their similarities. There is a good agreement among the eight observation datasets, albeit with some differences. The two simulation datasets (CORDEX and NEX) capture the climatology of rainfall indices over southern Africa and, in some cases, the simulation errors fall within the observation uncertainties. CORDEX and NEX datasets agree on fewer rain days but more intense rainfall events over southern Africa in the future and indicate that the magnitude of these changes increases with the GWLs. They also agree on a future increase in the frequency and intensity of extreme rainfall events north of 20°S and a decrease south of 20°S. However, CORDEX indicates that the rainfall deficit from the fewer rain events may exceed the rainfall surplus from the more intense rain events, but NEX indicates the opposite. In the SOM classification, while some simulations project a decrease in tropical temperate trough (TTT) rainfall, some project an increase, and some indicate an equatorward shift of the TTT rainfall. The simulations project a decrease in annual rainfall over five cities, an intensification of extreme rainfall over five cities and more frequent extreme rainfall events over four cities. The results of this study have application in mitigating the future impacts of extreme rainfall events over southern Africa, especially in the cities.