Decline In Rainfall Research Articles

Will Warming Climate Affect the Characteristics of Summer Monsoon Rainfall and Associated Extremes Over the Gangetic Plains in India?

AbstractThe Indo‐Gangetic Plain (IGP) bears great agricultural importance and contributes to a major share of national GDP of India. In present study, a location‐specific comprehensive analysis of rainfall extremes over IGP, using second generation CORDEX‐CORE simulations in the present and future scenarios (under high emission RCP8.5 scenario) have been performed. Here, the high‐resolution CORDEX‐CORE simulations with International Centre for Theoretical Physics's regional climate model (RegCM4.7) have been considered for the detailed rainfall characteristics assessment. Twelve thresholds‐based climate indices have been analyzed to investigate the characteristics of rainfall extremes during three‐time slices: 1986–2005 (historical), 2041–2060 (near future) and 2080–2099 (far future). The RegCM4 projections suggested a substantial decline in mean Indian Summer monsoon rainfall (ISMR) and wet days (rainfall ≥ 1 mm; 7%–14%) over IGP under high‐emission RCP8.5 scenario. The contribution of 90th and 99th percentile days and total rainfall on wet days, seems to be get enhanced in future by 14%–35%, which implies the increase and intensification in rainfall extremes over IGP by the end of the 21st century. Further, the decline in ISMR and negligible changes in annual rainfall over IGP suggest the possible shift of monsoon regime during the later months of the year in warming climate. Thus, findings of present study may play a crucial role in predicting the ISMR and rainfall extremes over the IGP. Therefore, it can be useful for scientists and policymakers to plan and implement mitigation strategies.

Impact Of Climate Change In Agricultural Production: A Case Of Koshi River Basin, Nepal

The climatic factor has played dominant role on affecting agricultural production in the region. This study focused on analyzing the impact of Climate change in agricultural production in two districts of Nepal. Sunsari district had experienced the highest annual temperature increased (0.0038°C/yr) during 1990 and 2022, whereas the Saptari district had faced sharp decline in rainfall (11.442 mm/yr). Climate change resulted into climate induced disasters such as recurring drought, catastrophic flooding, mass wasting and emergence of pests. The climate data during 1990 and 2022, was used to find climate trend analysis. The inter-annual climatic patterns across time were examined using the trend analysis test and trend line slope. The HH survey concluded with increased in temperature and crop diseases emergence along with increase in the frequency of pests, drought and floods, and decreased in rainfall as perceived by majority of respondents. These parameters were expected to cause negative effect on crop output, human health, animals and vegetation. An increasing tendency in temperature and declining trend in precipitation were the two main climatic trends that were observed in the study area. Climate trends in Barahakshetra of Sunsari district of the KRB showed an increasing rate of precipitation of 7.8021 mm/year. The linear trend analysis of pre-monsoon time showed the precipitation was increasing at the rate of 3.4424 mm/year. The trend of post-monsoon rainfall increased significantly at the rate of 1.7956 mm/year. The Climatic trends as indicated by Barmajhiya Station in the Saptari district of the KRB showed decreasing rate of annual precipitation with 11.442 mm/year. In Saptari district, the annual production of paddy has been observed in decreasing trend of 1092.9 Mt. per year, with the increasing trend of cultivation area with 673.55 ha per year. The decreasing trend of cultivation area was observed with 17.918 ha per year. The HHs survey ascertained that, the majority of respondents perceived the increased temperature and drought with heavy rainfall and flood in the locality. The springs and ponds were at stake resulting into water scarcity with low discharge in rivers.

Can southern Australian rainfall decline be explained? A review of possible drivers

AbstractSouthern Australia's rainfall is highly variable and influenced by factors across scales from synoptic weather to large‐scale circulation and remote climate modes of variability. Anthropogenic climate change and natural variability modulate these factors and their interactions. However, studies often focus on changes in selected parts of the climate system with less emphasis on the system as a whole. As such, it is difficult to gain a complete understanding of how southern Australia's rainfall responds to broad‐scale changes in the climate system. We step through the existing literature on long‐term changes in synoptic‐to‐large‐scale atmospheric circulation and drivers of climate variability to form a more complete story of rainfall changes across southern Australia. This process reveals that the most robust change is the observed winter decline in rainfall as it is consistent with several changing climatic factors: decreasing rainfall from weather systems, strengthening subtropical ridge, poleward shifts in the Hadley Cell and the Southern Annular Mode, and increasing frequency of positive Indian Ocean Dipole events. In other seasons, particularly summer, changes in atmospheric circulation and drivers may not agree with observed rainfall changes, highlighting gaps in our knowledge of atmospheric dynamics and climate change processes. Future work should focus on research across temporal‐ and spatial‐scales, better understanding of jet interactions, the influence of stratospheric processes on the troposphere, and instances of contrasting trends in drivers and southern Australian rainfall changes.This article is categorized under: Paleoclimates and Current Trends > Modern Climate Change Paleoclimates and Current Trends > Detection and Attribution Assessing Impacts of Climate Change > Observed Impacts of Climate Change

Data assimilation, sensitivity analysis and uncertainty quantification in semi-arid terminal catchments subject to long-term rainfall decline

Quantification of long-term hydrologic change in groundwater often requires the comparison of states pre- and post-change. The assessment of these changes in ungauged catchments using numerical models and other quantitative methods is particularly difficult from a conceptual point of view and due to parameter non-uniqueness and associated uncertainty of quantitative frameworks. In these contexts, the use of data assimilation, sensitivity analysis and uncertainty quantification techniques are critical to maximize the use of available data both in terms of conceptualization and quantification. This paper summarizes findings of a study undertaken in the Lake Muir-Unicup Natural Diversity Recovery Catchment (MUNDRC), a small-scale endorheic basin located in southwestern Australia that has been subject to a systematic decline in rainfall rates since 1970s. A combination of data assimilation techniques was applied to conceptual and numerical frameworks in order to understand and quantify impacts of rainfall decline on the catchment using a variety of metrics involving groundwater and lake levels, as well as fluxes between these compartments and mass balance components. Conceptualization was facilitated with the use of a novel data-driven method relating rainfall and groundwater responses running backwards in time, allowing the establishment of the likely baseline conditions prior to rainfall decline, estimation of net recharge rates and providing initial heads for the forward numerical modelling. Numerical model parameter and predictive uncertainties associated with data gaps were then minimized and quantified utilizing an Iterative Ensemble Smoother algorithm, while further refinement of conceptual model was made possible following results from sensitivity analysis, where major parameter controls on groundwater levels and other predictions of interest were quantified. The combination of methods can be considered as a template for other long-term catchment modelling studies that seek to constrain uncertainty in situations with sparse data availability.

Holocene vegetational and climatic history of the Xuguo Co catchment in the central Tibetan Plateau

A 101-cm core was taken from a large lake in the central Tibetan Plateau. Its pollen and loss-on-ignition analyses provide a Holocene vegetational, climatic, and environmental history of the lake catchment. Pollen analysis shows that: dense steppe dominated regional vegetation in the early Holocene (9,200–8,000 cal. yr BP); regional vegetation coverage gradually decreased in the middle Holocene (8,000–4,100 cal. yr BP); and marsh meadow grew on the lake edge and sparse steppe occupied the lake catchment after 4,100 cal. yr BP. Our result also reveals that: 9,200–8,000 cal. yr BP witnessed summer temperature, monsoonal rainfall, and lake-level maxima, as well as few winter and spring aeolian activities and frequent wildfires; 8,000–4,100 cal. yr BP saw a nonlinear decline in temperature, rainfall, lake level, and wildfires; and modern climatic and environmental conditions were established after 4,100 cal. yr BP. Three major monsoon-weakening events at ca. 6,700, 5,800, and 4,100 cal. yr BP were detected by pollen signals and proxies of the climate and environment.

The changing characteristics of rainfall over the Brahmaputra Basin during 1998–2018

AbstractThe changes to the hydrological cycle as a consequence of climate change significantly affect the water security of countries worldwide. The Brahmaputra Basin (BB), a biodiversity hotspot, is among the world's wettest regions and is vulnerable to climate change. Using ground and satellite‐based datasets from multiple sources and a percentile‐based analysis from 1998 to 2018, it is found that an asymmetric trend exists in extreme rainfall over the hills and the adjacent plains of the basin. The hills experience a decline in rainfall, whereas, over the plains, an increase is observed on similar rainfall days. During 1998–2018, mean accumulated rainfall over the whole basin declined by as much as ∼60% during the October to December (OND) period. Similarly, a decline of ∼20% is observed for June to September (JJAS). The most significant reduction in mean rainfall was mainly over the wettest regions of the basin, such as Cherrapunji/Mawsynram and is concentrated in the highest percentile (extreme events) of rainfall distribution. Such an overall decline in total rainfall coupled with altitudinal asymmetry in percentile distributions of rainfall may contribute towards flood hazards with changing lead time for warning, posing severe socio‐economic challenges.

Determinants of Climate Change Adaptation Strategies in Bundelkhand Region, India

The study attempted examining climate change adaptation strategies in the most backward regions of India, i.e., the Bundelkhand region. Data were collected from 200 farmers during April and May of 2017, and a binary logistic regression model was used to analyze the data. The farmers were most likely to improve irrigation facilities if they have access to institutional credit, information about the weather, and have taken crop insurance. Also, farmers perceived that an increase in temperature, a decline in rainfall, and a decline in water tables motivate and influence farmers to change their cropping pattern from wheat (a water-intensive crop) to chickpea (a less water-intensive crop) to cope with the changing climate. Hence, the present study recommends that since water table is declining continuously and creating water crisis even in the rainy season for agriculture and domestic consumption, community participation in the conservation of water-bodies is vital. Further, the adoption of crop varieties that require less water, are drought tolerant and mature early will help increase farm productivity and reduce cultivation costs. Lastly, an advance regional weather forecasting system capable of providing farmers with accurate information that will enable them to change cropping patterns and adjust farming practices are required.

Climate change impact on water availability in the Himalaya: Insights from Sunkoshi River basin, Nepal

Changing streamflow is one of the most visible consequences of climate change. In this study, the Soil and Water Assessment Tool (SWAT) model was used to investigate the significant effects of climate change on streamflow in a Himalayan River. We incorporated information from several Global Climate Models (GCM), considering two climate scenarios: SSP 2.45 and SSP 5.85, which are part of Shared Socioeconomic Pathways (SSPs) for the future periods of 2022–2030 and 2031–2050. Substantial patterns in temperature and rainfall changes were identified using ensemble modeling. Under both SSPs 2.45 and 5.85, the results indicated a rising trend in temperatures from January to June, a decline from June to September, and a marginal increase from October to December. Additionally, annual rainfall, real evapotranspiration, and river flow are anticipated to rise by 17.67–21.79%, up to 0.93%, and 23–53%, respectively in the upper region of the study basin. Conversely, across the two future periods and scenarios, the lower region is depicted to have a decline in rainfall of 20.84–36.34%, evapotranspiration of up to 4.35%, and river flow of 38–65%. These findings will be invaluable for the design and construction of climate-resilient water resources related projects in the Himalayan regions, such as Nepal.

Climate variability and change in the spices and plantation cropping systems in Kerala state, India

Kerala state in India has rich bio-diversity and tropical rain forests and is spread in 13 agro-ecological zones under the humid tropics. Rainfall decline (annual as well as monsoon), increase in temperature and climate shift towards lesser humid zones within the humid climate are the notable characteristics of the state. Cropping system changes, as well as changes in the production of spices and plantation crops in Kerala, were analyzed from 1952-53 to 2018-19. Area and production changes of various crops in the Idukki district have also been studied and presented in this paper. The average temperature in Kerala has risen by 0.65 °C from 1956 to 2014. In Idukki high ranges, the maximum temperature is increasing, and the minimum temperature is declining, resulting in a widening of temperature ranges. Such a scenario may adversely affect the thermo-sensitive crops, which may need urgent attention as these crops are grown in the forest-agro-ecosystems across the Cardamom Hill Reserve (CHR) of the Idukki district. Deforestation, the shift in cropping systems, declining wetlands, and depletion of surface and groundwater resources had deepened the adverse effects of floods and droughts on spice and plantation crops. Therefore, there is an urgent need for proactive steps on a short and long-term basis against the climate change risks for the sustenance of crop production both in terms of quality and volume.

Trends, impacts, and local responses to drought stress in Diamare Division, Northern Cameroon

Drought is one of the climatic events that threaten water availability, food security, and local livelihoods in semi-arid areas. Whilst studies have evolved on the impacts of climate change on humanity, especially in Sub-Saharan Africa, limited scholarly insight exists on the impacts of specific climatic stressors and shocks and how residents respond to such. This study contributes to climate change policy planning debates by analysing the trends, impacts and local responses to drought drawing on household questionnaires, participatory field observations, key informant interviews, and focus group discussions. The CUSUM and Mann-Kendall tests were used to analyse weather data (rainfall and temperature) to establish their trends. The Standardized Precipitation Index (SPI) was used to determine drought occurrences and intensities. The results showed significant variation: rise and decline in temperature and rainfall over the years. The SPI (range from -0.01 to -2.8) indicated extreme, severe, moderate, and mild drought (mild (73%) being the notorious) event that instigated crop failure, drying of water sources, loss of pasture, food shortages, high prices of foodstuffs, malnutrition, water scarcity, and health problems and loss of livestock. Households responded by utilizing crop residues and tree branches as fodder for livestock, reducing the number of times households eat, and changing crop varieties and planting dates. This study argues that considering the geographical variation of climatic shocks and stressors, a focus on the specific climatic event may offer the possibility for an in-depth understanding of its impacts on local residents, and useful for engendering climate planning policy intervention in Sub-Saharan Africa.

Delineating Groundwater Potential Zones in Hyper-Arid Regions Using the Applications of Remote Sensing and GIS Modeling in the Eastern Desert, Egypt

The increasing demand for freshwater supplies and the effects of climate change in arid and hyper-arid regions are pushing governments to explore new water resources for food security assurance. Groundwater is one of the most valuable water resources in these regions, which are facing water scarcity due to climatic conditions and limited rainfall. In this manuscript, we provide an integrated approach of remote sensing, geographic information systems, and analytical hierarchical process (AHP) to identify the groundwater potential zone in the central Eastern Desert, Egypt. A knowledge-driven GIS-technique-based method for distinguishing groundwater potential zones used multi-criteria decision analysis and AHP. Ten factors influencing groundwater were considered in this study, including elevation, slope steepness, rainfall, drainage density, lineament density, the distance from major fractures, land use/land cover, lithology, soil type, and the distance from the channel network. Three classes of groundwater prospective zones were identified, namely good potential (3.5%), moderate potential (7.8%), and poor potential (88.6%) zones. Well data from the study area were used to cross-validate the results with 82.5% accuracy. During the last 8 years, the static water level of the Quaternary alluvium aquifer greatly decreased (14 m) due to excessive over pumping in the El-Dir area, with no recorded recharges reaching this site. Since 1997, there has been a noticeable decline in major rainfall storms as a result of climate change. The current study introduces a cost-effective multidisciplinary approach to exploring groundwater resources, especially in arid environments. Moreover, a significant modern recharge for shallow groundwater aquifers is taking place, even in hyper-arid conditions.

Awareness and Perceptions of Climate Variability Adaptation among Forest-adjacent Communities in Mau Forest, Kenya

Adequate knowledge of climate variability is essential for the success of any adaptation or mitigation efforts. Thus, a study was conducted to investigate the levels of awareness and perceptions on the adaptation of climate variability among forest-adjacent communities (FACs) in Mau Forest, Kenya. Data for the investigation was generated through the administration of 313 questionnaires across randomly selected forest-adjacent households. Of the entire questionnaire, 311 were analysed, while two were returned uncompleted and therefore discarded. Descriptive and inferential statistical analyses were conducted. Descriptive analysis showed that 96% of the respondents had knowledge of climate variability, while 4% claimed no knowledge of it. Nearly two-thirds of respondents (65%) reported that they receive weather information, with media (electronic and print) cited as the most common (63%) source of this information. As regards frequency of information, those respondents who get information about climate variability occasionally constituted 60%, while 29% of respondents received information frequently. However, 14% of respondents rarely received any climate-related information. Respondents who received climate-related information occasionally (sometimes) constituted 56%. Alternatively, respondents reported that they obtained weather information from agricultural extension officers (17.6%) and Kenya Forestry Service (KFS) officials (15.3%). The perceptions of the farmers that they had observed erratic weather patterns with a general decline in rainfall and an increase in temperatures were corroborated by scientific data as a trend analysis on rainfall and temperature data over a 20-year period mirrored the farmer’s perceptions. A logistic regression model was fitted to determine the socioeconomic factors that influence farmers’ choice of adaptation to climate variability. The ANOVA test results (F-test) show that overall, the logistic regression model was significant (df = 310, p = 0.002). Results of the model revealed that household head age (df = 310, p = 0.015), household head years of residency (df = 310, p = 0.034), and farming experience (df = 310, p = 0.024) were all significant factors that influence FACs’ decision to adopt to climate variability either positively or negatively. This study therefore recommends for more awareness creation and training of FACs of East Mau on how to identify and deal with changing climatic conditions.

Vegetation Shift of Juniperus macropoda Boisser Forest in Response to Climate Change in North-Western Himalayas, India

The cold desert ecosystem of the north-western Himalaya in India’s is considered to be the most vulnerable region to climate change. In this region, Juniperus macropoda Boisser grows across an altitudinal gradient and is highly sensitive to biotic, physiographic, and climatic factors. Keeping this in view, the present study aimed at ascertaining the response of Juniperus macropoda to changing climatic conditions. To achieve the target of the study, the area (elevation ranges from 3525 to 4150 m asl) was divided into thirteen elevation ranges in the cold desert of Lahaul valley (Himachal Pradesh). The NDVI change detection map from 1994–2017 revealed an increase in the area under the vegetation in the NDVI range of 0–0.15 (240%) and 0.15–0.30 (32%), which indicated the emergence of grasses and new recruits in the area. An increase in the minimum and maximum temperature during monsoon and post-monsoon season correlated positively with the emergence of the recruits in a significant manner. Furthermore, a decline in rainfall during the monsoon period was also recorded which bears a significant positive correlation with the establishment of recruits. However, the increase in the precipitation during winter resulted in a positive effect on the emergence of recruits. The biophysical parameters, like average height, diameter as well as the average age of the dominant trees showed a declining trend with the elevation. However, the age histogram revealed that the majority of the establishment occurred around 1900 and between 1975–2010. The tree ring analysis of J. macropoda revealed that the species is shifting upward at a rate of 3.91 m year−1. Besides this, the area is experiencing the impact of climate change resulting in an increase in the area under vegetation and migration towards the higher elevation, and many species of lichens were also found to invade the bare rock.

Australia’s Future Extratropical Cyclones

Abstract Extratropical cyclones are responsible for the majority of total and extreme rainfall in many regions of the extratropics, including in southern Australia. Using an ensemble of projections from 12 regional climate models, we show that both the number of cyclone days and total cyclone-related rainfall are projected to decline across southern Australia during the twenty-first century. This is a robust signal in projections across models and explains more than 80% of projected declines in total cool-season rainfall in the region. Using cyclone-centered composites, we show that cyclone intensity based on wind speed is projected to decrease but cyclone maximum rainfall is projected to increase by close to 7% K−1 in the southeast. This results in a shift in the distribution of cyclone rainfall, with a decrease in moderate rainfall but little change or an increase in extreme rainfall. Significance Statement Extratropical cyclones are very important for southern Australian rainfall, and they are expected to become less frequent in a warming climate. Our research shows this explains at least 80% of the projected decline in cool-season rainfall in southern Australia. However, the frequency of extratropical cyclones with very heavy rainfall may increase, particularly in Tasmania and the southeast coast, with increases in rainfall intensity in line with the Clausius–Clapeyron relationship. This contributes to increases in the frequency of very heavy rainfall in the future.

Hydro-Climate Variability and Trend Analysis in the Jemma Sub-Basin, Upper Blue Nile River, Ethiopia

Understanding hydro-climate variability in areas where communities are strongly dependent on subsistence natural resource-based economies at finer spatial resolution can have substantial benefits for effective agricultural water management. This study investigated the hydro-climate variability and trend of the Jemma sub-basin, in the Upper Blue Nile (Abbay) basin, using Mann–Kendall test, Sen’s slope estimator, and Standardized Precipitation Index (SPI). Climate data from 11 weather stations inside the basin and two major streams were used for the statistical analysis. The climate data were also correlated with the ENSO phenomenon to explain drivers of the variability. The results show that the sub-basin has been experiencing normal to moderate variability in the annual and Kiremt season rainfalls, but high variability and declining trend for 73% of the minor (Belg) season rainfall, negatively affecting the planting of short-cycle crops that account for about 20% of crop production in the study area. Generally, strong El Nińo (SST anomaly >1) has been correlated to a substantial decline in the Belg season rainfall. Stream-flow variability has also been found to be very high (CV > 30%) in both river flow monitoring stations. Subsequently, ensuring agricultural water security for short-cycle crop production seems to be a risky and daunting task unless supplemented with groundwater conjunctive use or water harvesting.

PERFORMANCE OF DAIRY COWS DURING DIFFERENT SEASONS WITH DAILY HERBAGE ALLOWANCE: A REVIEW

Pasture-based feeds are favored nowadays due to their cost-effectiveness and effect on animal welfare. Daily herbage allowance (DHA) affects the performance of dairy cows across different seasons. The key determinant of the performance of livestock is the dry matter intake (DMI) of herbage in pasture-based systems. A decline in average summer rainfall may result in considerably higher concentrate supplementation requirements to compensate for the loss in pasture growth and availability during autumn. Supplementation during autumn and winter boost total DMI and sustain milk output under grazing restrictions. Generally, milk production increases at high DHA but has no significant influence on milk fat content. In Spring, greater milk production lessens cows’ maintenance energy needs, and lower pasture content is linked to lower methane generation in the rumen. Methane generation declines in summer with increased digestibility at high intake levels. It is recommended to conduct an experiment exhibiting all seasons to eliminate factors that may affect the results across various studies. This review will understand variation in daily herbage intake of cows at pasture that allows the management of total intake to optimize milk production and identification of cows that are more efficient at converting feed into milk.

Eaten out of house and home: local extinction of Abrolhos painted button-quail Turnix varius scintillans due to invasive mice, herbivores and rainfall decline

Eaten out of house and home: local extinction of Abrolhos painted button-quail Turnix varius scintillans due to invasive mice, herbivores and rainfall decline

Reconstruction of Rainfall Records at 24 Observation Stations in Sumatera, Colonial Indonesia, from 1879 to 1900

Abstract This study reconstructed historical monthly rainfall data at 24 observation stations in Sumatera, Indonesia, for 22 years (1879–1900) during the Dutch colonial era. The literature research was conducted in libraries in Indonesia and the Netherlands to collect meteorological data recorded in a series of Regenwaarnemingen in Nederlandsch-Indië, which have never been reconstructed or analyzed previously. The results showed that the six western coast stations (97°–103°E, 3°N–4°S) have abundant rainfall exceeding 3000 mm yr−1, and the 10 eastern coast stations and three stations east of the Barisan ridge obtained rainfall below 3050 mm yr−1. Abundant coastal rainfall appeared only along the western coast, but not in the eastern coast and east of the Barisan ridge. The El Niño events of 1888/89 had low impact on rainfall amounts during the dry season (May–October) at the six stations of the Southern Hemispheric climate type. A significant decrease in annual dry-season precipitation was observed in 1881, 1885, and 1896. When comparing monthly data for 1931–60 and 1971–2014 at the northernmost station Banda Aceh (5.5°N, 95.3°E) and the eastern coast station Bengkalis (1.5°N, 102.1°E), a noticeable decrease and increase occurred in June–December and January–May, respectively, throughout the last century. The recent El Niño events have resulted in a decline in rainfall and dry conditions in Sumatera, but the Indian Ocean dipole had much influence on the amount of rainfall in the late-nineteenth century.

Early Anthropogenic Impacts on the Indian Summer Monsoon Induced by Land‐Use and Land‐Cover Changes

AbstractThe impacts of anthropogenic forcing on Indian summer monsoon (ISM) rainfall are obscure, partly due to limited availability of highly resolved hydroclimate proxy records as well as the highly regionalized nature of precipitation. Here, we report an annually‐resolved speleothem oxygen isotope record from Xianren Cave, southwestern China, which represents rainfall change over the broad ISM region. We find that the region has endured at least six decadal‐scale weak monsoon events in the past three hundred years. One of them, lasting from the early to mid 19th century, shares the similar gradual, persistent trend as the most recent decline in ISM rainfall and both have a magnitude substantially larger than the others dominated by natural variability. This early weak monsoon event occurred during a historical time of intensive deforestation in the region. We conclude that the ISM trend could have been altered by the changes in land‐use and land‐cover since the early 19th century.

Responses of water balance component to land use/land cover and climate change using geospatial and hydrologic modeling in the Gidabo watershed, Ethiopia

The impact of climate change (CC) and land-use/land-cover (LULC) change on water resources poses a major threat globally. This study investigates the separate and combined responses of CC and LULC change on water balance in Gidabo watershed, Ethiopia, using Soil and Water Assessment Tool (SWAT), Cellular Automata-Markov Chain, and regional climate models. CC projection under RCP 4.5 and hydrological modeling show a significant decline in mean annual surface runoff (Q), baseflow (BF), water yield (WY), percolation (PC), and evapotranspiration (ET) during mid-century (2027–2056) as well as late-century (2061–2090) compared to the baseline period (1988–2018) data, largely due to decline in rainfall. Likewise, under RCP 8.5 scenario, the modeling results show a decrease in Q, BF, WY, PC, and ET during these periods. The LULC change (often associated with an expansion in cultivated and urban areas and a reduction in evergreen forest and grassland) alone leads to a positive synergy with an increase in mean annual Q and WY and a negative synergy with a decrease in BF, PC and ET during the period 2018 to 2075. The combined effects of climate and LULC changes have also shown a decline in Q, BF, WY, PC and ET. Overall, the climate change impacts significantly the future Q and WY. However, the combined effect of climate and LULC changes on BF, PC, and ET is more prominent than their separate impacts and it underlines the significance of this study.