Decline In Rainfall Research Articles

TECHNICAL AND ECONOMIC FEASIBILITY OF SOLAR IRRIGATION PUMPING SYSTEM: A REVIEW

Climate change has become a major constraint to the development of rain-fed agriculture due to the decline of rainfall. Therefore, irrigated agriculture is an alternative allowing farmers to have more access to water in order to meet crop water requirements. However, irrigated agriculture faces a major constraint related to the accessibility of energy sources used in pumping water. In general, the most common energy sources used in pumping water for irrigation are fuel and electricity. Nevertheless, they are very expensive, are not always accessible particularly in rural areas in Africa and have a negative impact on the environment; hence the need to find alternatives to solve this problem. This review focuses on the technical and economic feasibility of solar irrigation pumps and the impact of their use on the environment. Several aspects related to solar pumping have been discussed, namely the components of the solar pumping system, the energy source used, the principle of operation of the system, the technical, economic, and environmental feasibility. Reviews show that the use of solar irrigation pumps is a technically and economically feasible alternative in several areas with less environmental impact.

Season of the drought

Indian Monsoon The Indian monsoon is a critical source of water for hundreds of millions of people, and when it fails to deliver its normal quantity of rain, enormous human, economic, and ecological costs can be incurred. Monsoon droughts are not always seasonal, however. Borah et al. found that nearly half of all monsoonal droughts were subseasonal and characterized by a steep decline in late-season rainfall. Moreover, this type of subseasonal drought appears to be related to a distinct cold anomaly in the North Atlantic Ocean, raising the possibility that monsoon droughts may be more predictable. Science , this issue p. [1335][1] [1]: /lookup/doi/10.1126/science.aay6043

Indian monsoon derailed by a North Atlantic wavetrain.

The forecast of Indian monsoon droughts has been predicated on the notion of a season-long rainfall deficit linked to a warm equatorial Pacific. Here we show that nearly half of all droughts over the past century differ from this paradigm in that they (i) occur when Pacific temperatures are near-neutral and (ii) are subseasonal phenomena, characterized by an abrupt decline in late-season rainfall. This severe subseasonal rainfall deficit can be associated with a Rossby wave from mid-latitudes. Specifically, we find that the interaction of upper-level winds with an episodic North Atlantic vorticity anomaly results in a wavetrain that curves toward East Asia, disrupting the monsoon. This atmospheric teleconnection offers an avenue for improved predictability of droughts, especially in the absence of telltale signatures in the Pacific.

Simulating adaptation strategies to offset potential impacts of climate variability and change on maize yields in Embu County, Kenya.

In this study, we assessed the possible impacts of climate variability and change on growth and performance of maize using multi-climate, multi-crop model approaches built on Agricultural Model Intercomparison and Improvement Project (AgMIP) protocols in five different agro-ecological zones (AEZs) of Embu County in Kenya and under different management systems. Adaptation strategies were developed that are locally relevant by identifying a set of technologies that help to offset potential impacts of climate change on maize yields. Impacts and adaptation options were evaluated using projections by 20 Coupled Model Intercomparison Project-Phase 5 (CMIP5) climate models under two representative concentration pathways (RCPs) 4.5 and 8.5. Two widely used crop simulation models, Agricultural Production Systems Simulator (APSIM) and Decision Support System for Agrotechnology Transfer (DSSAT) was used to simulate the potential impacts of climate change on maize. Results showed that 20 CMIP5 models are consistent in their projections of increased surface temperatures with different magnitude. Projections by HadGEM2-CC, HadGEM2-ES, and MIROC-ESM tend to be higher than the rest of 17 CMIP5 climate models under both emission scenarios. The projected increase in minimum temperature (Tmin) which ranged between 2.7 and 5.8°C is higher than the increase in maximum temperature (Tmax) that varied between 2.2 and 4.8°C by end century under RCP 8.5. Future projections in rainfall are less certain with high variability projections by GFDL-ESM2G, MIROC5, and NorESM1-M suggest 8 to 25% decline in rainfall, while CanESM2, IPSL-CM5A-MR and BNU-ESM suggested more than 85% increase in rainfall under RCP 8.5 by end of 21st century. Impacts of current and future climatic conditions on maize yields varied depending on the AEZs, soil type, crop management and climate change scenario. Impacts are largely negative in the low potential AEZs such as Lower Midlands (LM4 and LM5) compared with the high potential AEZs Upper Midlands (UM2 and UM3). However, impacts of climate change are largely positive across all AEZs and management conditions when CO2 fertilization is included. Using the differential impacts of climate change, a strategy to adapt maize cultivation to climate change in all the five AEZs was identified by consolidating those practices that contributed to increased yields under climate change. We consider this approach as more appropriate to identify operational adaptation strategies using readily available technologies that contribute positively under both current and future climatic conditions. This approach when adopted in strategic manner will also contribute to further strengthen the development of adaptation strategies at national and local levels. The methods and tools validated and applied in this assessment allowed estimating possible impacts of climate change and adaptation strategies which can provide valuable insights and guidance for adaptation planning.

The Impact of Climate Change on the River Jordan-Lake Kinneret (Israel) Ecosystem

The long-term record of River Jordan-Lake Kinneret ecosystem indicates some significant climate condition changes: water temperature increase, decline in rainfall, and diminishing river discharges and lake water inflows accompanied by a reduction in nitrogen and a slight increase in phosphorus in the Lake upper layers (Epilimnion). Lake Water level decreased, Prolongation of Residence Time was documented, nutrient inputs and dynamics modifications resulting water quality deterioration. As a result of temperature elevation and nitrogen deficiency, the biomass of Peridinium spp significantly reduced and was replaced by Cyanobacterial biomass enhancement. Dryness trend expressed as enhanced frequency of drought seasons initiated an elevation of lake water salinity. It has been suggested that these changes in the phytoplankton community structure are caused by regional climate change. This study evaluates a multi-annual respective approach although the summer is the most critical. The objective of this research is evaluate the background of the ecosystem structure modification aimed at define future potential management design.

Anthropization and Climate Change: Impact on the Discharges of Forest Watersheds in Central Africa

Climate change and anthropization are major drivers of river flows variability. However, understanding their simultaneous impact on discharges is limited. As a contribution to address this limitation, the objective of this study is to assess the impact of climate change and anthropization on the discharges of two watersheds of Central Africa (Nyong and Ntem) over a recent period. For this, the hydropluviometric data of the watersheds concerned were analyzed using the Pettitt test. Similarly, the dynamics of the main land use modes (LUM) have been assessed, through classifications obtained from the processing of Landsat satellite images of the watersheds studied on two dates. The results of this study show that in Central Africa, annual discharges have decreased significantly since the 1970s, and yet the decline in annual rainfall does not become significant until the 2000s. The discharges of the rainy seasons (spring and autumn) recorded the most important changes, following variations in the rainfall patterns of the dry seasons (winter and summer) that precede them. Winters experienced a significant decrease in precipitation between the 1970s and 1990s, which caused a drop in spring flows. Their rise, which began in the 2000s, is also accompanied by an increase in spring flows, which nevertheless seems rather slight in the case of the Nyong. Conversely, between the 1970s and 1990s, there was a joint increase in summer rainfall and autumn flows. A decrease of summer rainfall was noted since the 2000s, and is also noticeable in autumn flows. Maximum flows have remained constant on the Nyong despite the slight drop in rainfall. This seems to be the consequence of changes in land use patterns (diminution of forest and increasing of impervious areas). The decrease in maximums flows noted on the Ntem could be linked to the slight drop in precipitation during the rainy seasons that generates it. Factors such as the general decrease in precipitation during the winter and the reduction in the area occupied by water bodies could justify the decrease in minimum flows observed in the two watersheds. These findings would be vital to enhance water management capabilities in the watersheds concerned and in the region. They can also give some new elements to study and understand the seasonal variation and fresh water availability in downstream, estuaries and coastal areas of the regional rivers.

The Impact of Anthropogenic Forcing and Natural Processes on Past, Present, and Future Rainfall over Victoria, Australia

AbstractCool-season (April to October) rainfall dominates the annual average rainfall over Victoria, Australia, and is important for agriculture and replenishing reservoirs. Rainfall during the cool season has been unusually low since the beginning of the Millennium Drought in 1997 (~12% below the twentieth-century average). In this study, 24 CMIP5 climate models are used to estimate 1) the extent to which this drying is driven by external forcing and 2) future rainfall, taking both external forcing and internal natural climate variability into account. All models have preindustrial, historical, and twenty-first-century (RCP2.6, RCP4.5, and RCP8.5) simulations. It is found that rainfall in the past two decades is below the preindustrial average in two-thirds or more of model simulations. However, the magnitude of the multimodel median externally forced drying is equivalent to only 20% of the observed drying (interquartile range of 40% to −4%), suggesting that the drying is dominated by internally generated rainfall variability. Underestimation of internal variability of rainfall by the models, however, increases the uncertainties in these estimates. According to models the anthropogenically forced drying becomes dominant from 2010 to 2029, when drying is evident in over 90% of the model simulations. For the 2018–37 period, it is found that there is only a ~12% chance that internal rainfall variability could completely offset the anthropogenically forced drying. By the late twenty-first century, the anthropogenically forced drying under RCP8.5 is so large that internal variability appears too small to be able to offset it. Confidence in the projections is lowered because models have difficulty in simulating the magnitude of the observed decline in rainfall.

Decline of soil respiration in northeastern Tibet through the transition into the Oligocene icehouse

Soil respiration (Rs), the production of carbon dioxide in soils, increases dramatically from deserts to forested ecosystems. Rs values thus provide a potential tool to identify past ecosystems if recorded in sedimentary archives. Here, we propose a quantitative method to reconstruct past Rs values from paleosols. This method reverses the soil paleobarometer, a proxy that estimates past atmospheric CO2 concentration values (CO2atm) from paleosols while considering a narrow range of variation for Rs. We use past CO2atm values from marine proxies to reconstruct soil respiration from a 20 million year-long isotopic record from northeastern Tibet covering the transition from the Eocene greenhouse to the Oligocene icehouse. We show that Rs dropped at least 4-fold through the transition into the Oligocene icehouse, marking the spread of boreal desert-steppes of Central Asia. We show that increasing aridity and the decline of monsoonal rainfall, in parallel with global cooling, caused the fall of soil respiration. These highly dynamic Rs emphasize the need for a systematic screening of paleosol isotopic data before using the soil paleobarometer to reconstruct CO2atm

Climate change-induced droughts and tourism: Impacts and responses of Western Cape province, South Africa

Climate change has led to several extreme weather events across the world. One such weather extreme is drought. Drought phenomenon has been increasing in both frequency and intensity globally of late. To this end, there has been growing concern about the impact droughts have and will have on the tourist destinations in sub-Saharan Africa and beyond. In this study, which employs a mixed-methods approach utilising primary, archival and secondary data, we examine the impact of the 2015–2018 drought episodes on the tourism industry in the Western Cape as well as the industry's response. These drought episodes famously led to the Day Zero phenomenon, a situation that could have resulted in taps running dry at some point. The study found that the drought led to a severe decline in tourist arrivals at the major tourist attractions in the Western Cape province as well as a decline in tourist spending and hotel occupancy. This resulted in a loss of potential revenue and jobs. The province had been experiencing a decline in rainfall that drastically affected water supplies; a trend likely to recur in the future. During and after the drought, the tourism industry adopted several measures aimed at augmenting and saving water, thereby easing the sector's water demand. We recommend that the tourism sector and the Western Cape province build on the successes and lessons learnt during the Day Zero campaign to prepare for the future. This would allow the province to address Sustainable Development Goal 6, focusing on water and sanitation as a part of embracing responsible and sustainable tourism. Hence, continuous research, innovation and investment in the water-smart industry is a must for Cape Town and the Western Cape province. • There is an increasing demand for the sector to improve water efficiency and security. • There is a need for the tourism industry to develop models for managing droughts. • Western Cape provides critical lessons on combating drought within the tourism sector. • Tourism needs to invest in water harvest technology to ensure water independency. • Tourism and recreation must adapt and mitigate climate change to ensure sector resilience.

Identification of Optimum Temperatures for Photosynthetic Production in Subtropical Coastal Ecosystems: Implications for CO2 Sequestration in a Warming World

AbstractTerrestrial ecosystems are often thought to be effective sinks of anthropogenic CO2 emissions with biosphere greening considered unequivocal evidence of this process. Increasing atmospheric concentrations of CO2 along with other greenhouse gases are however, responsible for global warming. As temperature increases, the rate at which biomes sequester CO2 may decline as the optimum temperature for photosynthetic production is exceeded, thereby reducing their potential to sequester CO2. Here we present evidence from 3 years of direct measurements of CO2 exchanges over subtropical coastal ecosystems in eastern Australia that the optimum temperature range for photosynthesis of 24.1°C to 27.4°C is routinely exceeded. This causes a rapid decline in photosynthetic production made worse when soil water content decreases. As climate change continues, both rising temperatures and predicted decline in rainfall will see these coastal ecosystems ability to sequester CO2 decrease further rapidly. We suggest similar research is needed urgently over other terrestrial ecosystems.

Prioritization of watershed management scenarios under climate change in the Jemma sub-basin of the Upper Blue Nile Basin, Ethiopia

Study regionJemma sub-basin, Upper Blue Nile Basin, Ethiopia. Study focusThis study develops watershed management alternatives which can ensure optimal climate change adaptation benefits under different climate scenarios. The climate scenarios were developed using the statistically bias corrected, multi-model ensemble mean and the RCP 4.5 and RCP 8.5 emission scenarios. The hydrological impact of climate change was assessed using a multi-gauge calibrated and validated the Soil and Water Assessment Tool (SWAT) model. Watershed management alternatives were prioritized using a multi-criteria decision analysis which intercompared watershed management criteria and alternatives through the Analytic Hierarchy Process. New hydrological insightsThe findings showed a consistent decline of rainfall, surface runoff and total water yield under all climate scenarios and climate impact scenarios. Water harvesting structures were the most prioritized watershed management alternatives to reduce climate change impacts. More than half of the watersheds of the Jemma sub-basin are highly and optimally suitable for in-situ water harvesting under baseline and future climate scenarios. Observed terrace and anticipated in-situ water harvesting structures significantly (p < 0.05) reduced surface runoff and thereby significantly increase soil water under baseline and future climate scenarios. However, both in-situ and ex-situ water harvesting structures caused an insignificant change in the total water yield under climate scenarios. We conclude implementing in-situ water harvesting structures can help to increase green water without a decline in blue water.

Evidence for intensification of meteorological droughts in Oman over the past four decades

Spatial and temporal variability of drought in Oman was assessed for the period 1979–2014 using the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) at both seasonal (3-month) and annual (12-month) timescales. Changes in drought characteristics (e.g. frequency, duration, intensity, severity, and spatial extent) were detected for six distinct climatic regions delineated using a Principal Component Analysis (PCA). Results suggest a statistically significant increase in the frequency and severity of drought during the past four decades. Nonetheless, drought exhibited pronounced decadal variability, with more frequent and severe droughts occurring after 1997/1998. Also, results demonstrate that the areas influenced by extreme and very extreme droughts witnessed a statistically significant increase on the order of 0.13% and 0.18%/decade, respectively, compared to −0.06%/decade for the areas impacted by mild droughts. Spatially, there has been a prevalent drying trend in central and eastern regions of Oman, while a tendency towards wetter conditions was observed in northern Oman (especially in the Batinah plain). This study also investigates the time-varying dependency between climatic drivers of drought and large-scale circulation patterns using the cumulative annual mean (CAM) method. Results indicate an acceleration of drying after 1997/1998, mainly due to the warming sea surface temperature (SST) anomalies over the Atlantic Ocean in recent decades and also the shift of the Pacific Ocean circulation patterns (e.g. PDO and El Nino) from the positive to the negative mode at the end of the 1990s. These configurations are favorable for significant changes in the thermodynamic drivers of drought (i.e. air temperature and relative humidity), but have less influence on aerodynamic drivers (i.e. wind speed). The significant temperature rise in recent decades, combined with a significant decline of rainfall and relative humidity, can explain the prolonged drought episode lasting from 1998 to 2014. A comprehensive assessment of drought variability in a poorly-studied water-stressed region like Oman is of particular concern for stakeholders and policy-makers. This study provides meaningful conclusions and a basis for water resources management, agricultural and energy production, ecological protection, and contribute to more reliable drought mitigation strategies at the regional and national scales.

Visible evidence of climate change and its impact on fruit production in Nepal

In recent years, Nepal is experiencing visible impact of climate change in agriculture. This review paper describes the recent climate change pattern and phenomenon with its impact on fruit production in Nepal. Various researches suggest that change in temperature has played vital to reduce the level of soil organic carbon, and soil micronutrients. With exposure to extreme temperatures, insects may produce heat shock proteins, cryoprotectants and osmolyte compounds within their bodies to survive, so these insects can exist in such environment. Most of the researches resulted that higher temperature induces early flowering under the subtropics may result in low fruit-set because of abnormalities arising from prevailing low night temperatures. Similarly, insufficient chilling greatly influences flower initiation and fruit coloration along with deterioration in fruit texture and taste. Besides the effect of high and low temperature, papers also claimed that decline in rainfall from November to April adversely affects the winter and spring crops that ultimately reduces food production. Hence, organization related to fruit research, education and development in Nepal have to run effective program to bring new genetic sources that can resist the adverse effect of climate and may bring some positive vibe to tackle the climate change.

The Recent Decline and Recovery of Indian Summer Monsoon Rainfall: Relative Roles of External Forcing and Internal Variability

AbstractThe Indian summer monsoon (ISM) rainfall affects a large population in South Asia. Observations show a decline in ISM rainfall from 1950 to 1999 and a recovery from 1999 to 2013. While the decline has been attributed to global warming, aerosol effects, deforestation, and a negative-to-positive phase transition of the interdecadal Pacific oscillation (IPO), the cause for the recovery remains largely unclear. Through analyses of a 57-member perturbed-parameter ensemble of model simulations, this study shows that the externally forced rainfall trend is relatively weak and is overwhelmed by large internal variability during both 1950–99 and 1999–2013. The IPO is identified as the internal mode that helps modulate the recent decline and recovery of the ISM rainfall. The IPO induces ISM rainfall changes through moisture convergence anomalies associated with an anomalous Walker circulation and meridional tropospheric temperature gradients and the resultant anomalous convection and zonal moisture advection. The negative-to-positive IPO phase transition from 1950 to 1999 reduces what would have been an externally forced weak upward rainfall trend of 0.01 to −0.15 mm day−1decade−1during that period, while the rainfall trend from 1999 to 2013 increases from the forced value of 0.42 to 0.68 mm day−1decade−1associated with a positive-to-negative IPO phase transition. Such a significant modulation of the historical ISM rainfall trends by the IPO is confirmed by another 100-member ensemble of simulations using perturbed initial conditions. Our findings highlight that the interplay between the effects of external forcing and the IPO needs be considered for climate adaptation and mitigation strategies in South Asia.

Long-term influence of season of grazing and rainfall on vegetation in the eastern Karoo, South Africa

In the Nama-Karoo, South Africa, rainfall and grazing by livestock are two important drivers of botanical composition. Summer rains are advantageous particularly to the grass layer, whereas the characteristic dwarf shrubs survive better than grasses during drought, and benefit from rainfall during cool months. Heavy grazing by livestock during summer reduces the abundance of grasses, whereas winter grazing increases it. This study examined the influences of season of grazing (summer vs winter) and rainfall on botanical composition at two long-term grazing trials at Grootfontein in the eastern Karoo from 1949 to 1967. Severe summer grazing strongly reduced grass abundance and slightly increased the abundance of both palatable and unpalatable dwarf shrubs. High previous-season rainfall strongly promoted short-lived grasses. Dwarf shrubs and grasses declined in response to a decline in annual rainfall over the study period, except for the creeping grass Tragus koelerioides that increased in abundance, possibly in response to decreased competition and an increase in available gaps in the vegetation layer. Results indicate that grazing systems that exclude repeated summer-only grazing maintain ecological health, and that rainfall is the main driver of composition unless extreme grazing systems are employed.

Analyzing Trend and Variability of Rainfall in The Tafna Basin (Northwestern Algeria)

Northwest Algeria has experienced fluctuations in rainfall between the two decades 1940s and 1990s from positive to negative anomalies, which reflected a significant decline in rainfall during the mid-1970s. Therefore, further analyzing rainfall in this region is required for improving the strategies on water resource management. In this study, we complement previous studies by dealing with sub basins that were not previously addressed in Tafna basin (our study area located in Northwest Algeria), and by including additional statistical methods (Kruskal–Wallis test, Jonckheere-Terpstra test, and the Friedman test) that were not earlier reported on the large scale (Northwest Algeria). In order to analyse the homogeneity, trends, and stationarity in rainfall time series for nine rainfall stations over the period 1979–2011, we have used several statistical tests. The results showed an increasing trend for annual rainfall after the break detected in 2007 for Djbel Chouachi, Ouled Mimoun, Sidi Benkhala stations using Hubert, Pettitt, and Buishand tests. The Lee and Heghinian test has detected a break at the same year in 2007 for all stations except Sebdou, Beni Bahdel, and Hennaya stations, which have a break date in 1980. We have confirmed this increasing trend for rainfall with other trend detection methods such as Mann Kendall and Sen’s method that highlighted an upward trend for all the stations in the autumn season, which is mainly due to an increase in rainfall in September and October. On a monthly scale, the date of rupture is different from one station to another because the time series are not homogeneous. In addition, we have applied three tests enabling further results: (i) the Jonckheere-Terpstra test has detected an upward trend for two stations (Khemis and Hennaya), (ii) Friedman test has indicated the difference between the mean rank again with Khemis and Hennaya stations and the Merbeh station, (iii) according to the Kruskal-Wallis test, there have been no variance detected between all the rainfall stations. The increasing trend in rainfall may lead to a rise in stream flow and enhance potential floods risks in low-lying regions of the study area.

On Tanzania’s Precipitation Climatology, Variability, and Future Projection

We investigate historical and projected precipitation in Tanzania using observational and climate model data. Precipitation in Tanzania is highly variable in both space and time due to topographical variations, coastal influences, and the presence of lakes. Annual and seasonal precipitation trend analyses from 1961 to 2016 show maximum rainfall decline in Tanzania during the long rainy season in the fall (March–May), and an increasing precipitation trend in northwestern Tanzania during the short rainy season in the spring (September–November). Empirical orthogonal function (EOF) analysis applied to Tanzania’s precipitation patterns shows a stronger correlation with warmer temperatures in the western Indian Ocean than with the eastern-central Pacific Ocean. Years with decreasing precipitation in Tanzania appear to correspond with increasing sea surface temperatures (SST) in the Indian Ocean, suggesting that the Indian Ocean Dipole (IOD) may have a greater effect on rainfall variability in Tanzania than the El Niño-Southern Oscillation (ENSO) does. Overall, the climate model ensemble projects increasing precipitation trend in Tanzania that is opposite with the historical decrease in precipitation. This observed drying trend also contradicts a slightly increasing precipitation trend from climate models for the same historical time period, reflecting challenges faced by modern climate models in representing Tanzania’s precipitation.

Recent unprecedented weakening of Indian summer monsoon in warming environment

All India summer monsoon rainfall (AISMR) shows a declining trend since 1953. Hence, the period 1953–2015 is considered for this study. The deviations of the summer monsoon (SM) rainfall in the recent period (1983–2015) from that of the previous period (1953–1982) have been evaluated for individual months and whole SM season using India Meteorological Department (IMD) gridded rainfall. The changes in the SM rainfall in the recent 3 decades with respect to the changes in the thermal, moisture, and circulation patterns over India and neighborhood are studied. The relationships between the winds over the Somali jet core region and the SM rainfall over India are quantified. Enhancement of rainfall activity is seen over a few subdivisions mainly Jammu & Kashmir and parts of Northwest India where the western disturbance interaction and the meridional wind component of low level jet (LLJ) have been pronounced. The decline in rainfall over major part of India in the recent 33 years is associated with weakened low level circulation, decrease in the relative humidity (RH) over the Bay of Bengal, less frequency of cyclonic disturbances formed in the Bay of Bengal, decrease in the genesis potential parameter as well as north-south sea level pressure gradient between Northern and Southern Hemispheres. The inconsistency of warming rates between Northern India and Southern India and its adjoining areas in the layer, 600–200 hPa induces reduced SM circulation. Further, the Walker and Hadley circulations specify a decline in the convective activity in SM season over the Indian mainland.

Spatiotemporal multi-index analysis of desertification in dry Afromontane forests of northern Ethiopia

Land degradation and desertification is a great concern of arid and semiarid areas. Desertification trends in northern Ethiopia were quantified using the Normalized Difference Vegetation Index (NDVI), Topsoil Grain Size Index (TGSI), and Precipitation Concentration Index (PCI) calculated from 1990 to 2018 Landsat imagery and meteorological data from fourteen stations. A decision tree approach was used to assess the rate of desertification in northern Ethiopia using 1990, 1995, 2000, 2008, 2014, and 2018 Landsat 5 TM+ and Landsat 8 OLI data. A significant decline (P 20%) from 2001 to 2016 due to frequent droughts, particularly in northeastern Ethiopia. This desertification hot spot was confirmed through semi-variogram analyses. The overall findings from the multi-index assessment indicate decreasing vegetation cover, increasing ratio of coarse soil particles, as well as decline and high seasonal variability in rainfall. The desertification also appears linked to the rapid reduction in dense forests and shrublands in favor of bare and desert land as well as agricultural land. Therefore, major causes of land degradation in northern Ethiopia are both anthropogenic and natural climatic factors, requiring mitigating and adaptation actions primarily in northeastern Ethiopia.

Predicted Climate Change Impact on Groundwater Flow for the Upper Zone of Iraqi Aquifers

A 3D groundwater steady-state flow conceptual model was built for all of Iraq using a MODFLOW package integrated with the Groundwater Modeling System to simulate the groundwater movement and flow direction for the upper zone of Iraq as well as to compute the water budget for all aquifer systems in Iraq. This model was run for seven scenarios of climate change conditions for the period of 2020–2050. A Representative Concentration Pathway model (RCP4.5) was used for the prediction of future rainfall over the next 31 years. The results showed that the decline in rainfall will be 6.247% due to climate change impacts. The decline in rainfall will cover two-thirds of the area of Iraq. Seven scenarios simulating groundwater flow behavior showed that decreased soil moisture content will significantly reduce groundwater recharge and increase runoff. A decline in groundwater levels by an average of 1.8–4.8 m will occur for the upper zone of Iraqi aquifers over the next 31 years. These results will help Iraqi decision-makers improve water resource management.