Consecutive Years Of Drought Research Articles

The frequency distribution and stochastic analysis of the hydrological drought in northern Algeria

The objective of this study was to examine drought using the Streamflow Drought Index (SDI) at various time scales and its temporal evolution using monthly streamflow data from 1973 to 2009. Streamflow records were collected from a network of 14 hydrometric stations distributed throughout the study area. The Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC) were used to assess the quality of the adjustment. According to these criteria, the gamma law better suited the time scales of 3, 6, and 12 months, whereas the log-normal law was better suited to the scale of 9 months. The analysis of the Streamflow Drought Index in the three study basins (Middle and Upper Cheliff, Lower Cheliff, and the Mina) revealed that different classes of drought among 3, 6, 9, and 12-month time scales in the period of 1973 to 2009 had occurred, notably beginning in 1980. The frequency of 19 to 54% was found at all stations and in years marked by a mild drought. The moderate years had a frequency of 6 to 19%, while the severe and extreme years had a lower percentage (about 3 to 6%) in the study area. Two consecutive years of drought (D-D) were more likely in the Middle and Upper Cheliff basins (> 60%) for the 6, 9, and 12-month time scales, according to the transition of probability of first-order non-stationary Markov chain. On a three-month time scale, the transition probabilities (D-D) were greater than 50% in the Coastal basin and Lower Cheliff basin, as well as the Mina basin, and less than 50% in the Middle and Upper Cheliff basins.

Forest growth resistance and resilience to the 2018–2020 drought depend on tree diversity and mycorrhizal type

Abstract The frequency of consecutive drought years is predicted to increase due to climate change. These droughts have strong negative impacts on forest ecosystems. Mixing tree species is proposed to increase the drought resistance and resilience of tree communities. However, this promising diversity effect has not yet been investigated under extreme drought conditions and in the context of complementary mycorrhizal associations and their potential role in improving water uptake. Here, we investigate whether tree diversity promotes growth resistance and resilience to extreme drought and whether drought responses are modulated by mycorrhizal associations. We used inventory data (2015–2021) from a young tree diversity experiment in Germany, manipulating tree species richness (1, 2 and 4 species) and mycorrhizal type (communities containing arbuscular mycorrhizal [AM] or ectomycorrhizal [EM] tree species, or both). For all tree communities, we calculated basal area increment in the periods before, during and after drought and used the concepts of resistance and resilience to quantify growth responses to drought. We found strong growth declines during the extreme 2018–2020 drought for most tree communities. Contrary to our hypothesis, we did not find that tree species richness per se can buffer the negative impacts of extreme drought on tree growth. However, while for EM communities, drought resistance and resilience decreased with tree species richness, they increased for AM communities and communities comprising both mycorrhizal types. We highlight that among various mixtures of tree species, only those with mixed mycorrhizal types outperformed their respective monocultures during and after drought. Furthermore, under extreme drought, the community tends to segregate into ‘winner’ and ‘loser’ tree species in terms of diversity, indicating a possible intensification of competition. While we cannot disentangle the underlying mechanisms or clarify the role of mycorrhiza during drought, our findings suggest that mixtures of mycorrhizal types within tree communities could help safeguard forests against increasing drought frequency. Synthesis. Drought resistance and resilience of tree communities depend on tree diversity and mycorrhizal association types. Mixing tree species with diverse mycorrhizal types holds promise for forest restoration in the face of climate change.

Assessing the small ruminant value chain in arid regions: A case study of the North-Eastern Badia Basalt Plateau in Jordan

This study aims to analyze the small ruminant value chain in the North-Eastern Badia region of Jordan, which is a significant source of income for local farmers. The objectives include characterizing the value chain, identifying stakeholders and their roles, and addressing the challenges it faces for long-term sustainability. Primary data was collected through a structured survey from 80 small ruminant holders in the district. The survey covered various aspects such as input supplies, husbandry practices, processing, marketing, and consumption. Additionally, individual interviews were conducted to analyze the value chain. The findings revealed a diverse range of actors involved in the value chain, including input suppliers, producers, animal collectors, traders, processors, and consumers. The SWOT analysis highlighted key issues such as high feed costs, limited and arid rangelands, inadequate government services, and unstable decisions. Moreover, neighboring small ruminant holders near Syrian refugee camps faced challenges related to land pollution caused by the refugees. In conclusion, besides to the negative impact of the climate change on the farms management due, particularly, to the consecutive drought years, the small ruminant value chain in the study area lacks organization and is not sufficiently supported by the governmental and non-governmental entities, and the Syrian refugees’ situation. Keywords: Small ruminant, Value chain, Sustainability, SWOT analysis, Jordan, North-Eastern Badia Basalt Plateau.

Hydrological Aspects of the Low-water Period of 2022 on the Lowland Section of the Tisza River

Climate change poses more and more challenges to the water management. Future predictions show that the possibility of extreme drought events are increasing, especially the rolling drought phenomena have become critical when consecutive years of drought multiply the adverse effects of previous years. These new extreme hydrological situations need to be properly handled in water management, thus an additional task of the water management can be the fulfilment of the increasing water demands. The article provides a comprehensive picture of factors influencing the formation of water scarcity period. The water supply of the Hungarian Great Plain is ensured by the water supply systems established in the last century. Coordinated water management is important in similar situations. The author describes the hydrological characteristics of last year’s water shortage period and how its harmful effects could be reduced.

How Exceptional Was the 2015–2019 Central American Drought?

AbstractThe Central American Dry Corridor experienced five consecutive years of drought from 2015 to 2019. Here, we find that the severity of this drought was driven primarily by rainfall deficits in July–August. To determine if the magnitude of this event was outside the range of natural variability, we apply a statistical resampling method to observations that emulates internal climate variability. Our analyses show that droughts similar to the 2015–2019 event are possible, although extremely rare, even without anthropogenic influences. Persistent droughts in our ensemble are consistently linked to stronger easterly winds associated with the Caribbean Low‐Level Jet. We also examine the effects of temperature on soil moisture during this drought using the Palmer Drought Severity Index and show that anthropogenic warming increases the likelihood of severe deficits. Multi‐year droughts are likely to worsen by the end of the 21st century due to the compound effects of anthropogenic climate change.

Outbreak Mechanism of Locust Plagues under Dynamic Drought and Flood Environments Based on Time Series Remote Sensing Data: Implication for Identifying Potential High-Risk Locust Areas

Locust plagues inflict severe agricultural damage. Climate change-induced extreme events like rainfall and droughts have expanded locust habitats. These new areas, often beyond routine monitoring, could become potential high-risk locust areas (PHRLA). Quantitatively understanding the outbreak mechanism driving drought and flood dynamics is crucial for identifying PHRLA, but such studies are scarce. To address this gap, we conducted a case study on locust outbreaks in Xiashan Reservoir, the largest reservoir in Shandong Province, China, in 2017 and 2018. Using time series satellite imagery and meteorological products, we quantitatively analyzed how drought–flood dynamics and temperature affect locust habitats, reproduction, and aggregation. Employing an object-oriented random forest classifier, we generated locust habitat classification maps with 93.77% average overall accuracy and Kappa coefficient of 0.90. Combined with meteorological analysis, we found that three consecutive drought years from 2014 to 2016 reduced the water surface area by 75%, expanding suitable habitats (primarily reeds and weeds) to cover 60% of the reservoir. Warm winters and high temperatures during locust key growth periods, coupled with expanding suitable habitats, promoted multi-generational locust reproduction. However, substantial flooding events in 2017 and 2018, driven by plentiful rainfall during key growth periods, reduced suitable habitats by approximately 54% and 29%, respectively. This compression led to high locust density, causing the locust plague and high-density spots of locusts (HDSL). Our study elucidates locust plague outbreak mechanisms under dynamic drought and flood environments. Based on this, we propose an approach to identify PHRLA by monitoring changes in drought and flood patterns around water bodies and variations in suitable habitat size and distribution, as well as surrounding topography. These findings hold significant implications for enhancing locust monitoring and early warning capabilities, reducing pesticide usage, and ensuring food and ecological security and sustainable agriculture.

Growth of European beech recovered faster than that of Norway spruce after a five-year experimental drought in a mixed forest stand

Key MessageBeech growth acclimated better during severe drought and recovered faster than spruce after drought ended. This was associated with a shift in performance along relative tree size towards small trees.The effects of several consecutive drought years and the recovery reaction of mature trees in particular after a long-term drought have been poorly studied so far. In this study, we demonstrate the growth reactions of mature trees during and after a five-year treatment of extended summer droughts, followed by controlled irrigation in a very productive mixed forest stand. We exposed 70-year-old Norway spruce (Picea abies [L.] Karst) and 90-year-old European beech (Fagus sylvatica [L.]) trees to reduced precipitation using automatic throughfall exclusion (TE) roofs during the growing seasons from 2014 to 2018, irrigated the trees in early summer 2019 and removed the roofs thereafter. From 2009 to 2022, we monitored annual tree growth and precipitation on 6 plots with throughfall exclusion and on 6 plots with ambient Control conditions (CO) of the KROOF canopy experiment. Norway spruce lost significant growth during drought, with some trees dying and others remaining at a low growth level without significant recovery from the effects of drought stress. European beech also significantly reduced growth at the beginning of the drought but emerged stronger in growth from the drought than the Control group. Spruce and beech showed a non-significant trend of increased inter-specific growth compared to intra-specific growth during drought. We found that spruce benefitted more from mixture than beech in the recovery phase after drought than during the drought phase itself. Most importantly, we observed a shift in growth performance along the relative tree size towards smaller trees in the TE plots for both species. This change in the relationship between diameter increment and tree size during and after drought is a major finding of our study and suggests a possible response mechanism to prolonged drought. This key observation requires further investigation and should be considered in future forest management strategies under changing climatic conditions.

Managing climate change impacts on the Western Mountain Aquifer: Implications for Mediterranean karst groundwater resources

Many studies highlight the decrease in precipitation due to climate change in the Mediterranean region, making it a prominent hotspot. This study examines the combined impacts of climate change and three groundwater demand scenarios on the water resources of the Western Mountain Aquifer (WMA) in Israel and the West Bank. While commonly used methods for quantifying groundwater recharge and water resources rely on regression models, it is important to acknowledge their limitations when assessing climate change impacts. Regression models and other data-driven approaches are effective within observed variability but may lack predictive power when extrapolated to conditions beyond historical fluctuations. A comprehensive assessment requires distributed process-based numerical models incorporating a broader range of relevant physical flow processes and, ideally, ensemble model projections. In this study, we simulate the dynamics of dual-domain infiltration and precipitation partitioning using a HydroGeoSphere (HGS) model for variably saturated water flow coupled to a soil-epikarst water balance model in the WMA. The model input includes downscaled high-resolution climate projections until 2070 based on the IPCC RCP4.5 scenario. The results reveal a 5% to 10% decrease in long-term average groundwater recharge compared to a 30% reduction in average precipitation. The heterogeneity of karstic flow and increased intensity of individual rainfall events contribute to this mitigated impact on groundwater recharge, underscoring the importance of spatiotemporally resolved climate models with daily precipitation data. However, despite the moderate decrease in recharge, the study highlights the increasing length and severity of consecutive drought years with low recharge values. It emphasizes the need to adjust current management practices to climate change, as freshwater demand is expected to rise during these periods. Additionally, the study examines the emergence of hydrogeological droughts and their propagation from the surface to the groundwater. The results suggest that the 48-month standardized precipitation index (SPI-48) is a suitable indicator for hydrogeological drought emergence due to reduced groundwater recharge.

Spatial and temporal pattern of deficient Indian summer monsoon rainfall (ISMR): impact on Kharif (summer monsoon) food grain production in India.

Despite a significant increasing trend in historical food grain production (FGP) in India, deficient Indian summer monsoon rainfall (ISMR) often causes a reduction in FGP. The present study was carried out to understand temporal and spatial variations in deficient rainfall (drought) and their impact on national and regional FGP of India. Long-term (1901-2020) percentage departure in rainfall and drought areas over the country showed nonsignificant and significant trends, respectively. Subdivisional rainfall showed significant decreasing and increasing trends in 4 and 5 subdivisions, respectively. Drought years of high frequency (once in 3-4years) and 4 to 5 consecutive drought years (once in 120years) occurred in northwest and western subdivisions of India. Departure in de-trended production of All India Kharif food grains from its normal (DDP) showed significant quadratic relationship with departure in ISMR from its normal (DRF). Besides the quadratic equation, another multiple regression model taking de-trended crop area, DRF, and drought area as predictor variables was developed for predicting DDP. Both these models, with high R2 (0.8-0.88) between observed and predicted data and low RMSE (2.6-2.7%), can be employed for advanced estimation of DDP of the country and for taking country-level policy decisions by the Indian Government. For the first time, models were formulated to estimate state-wise departure in FGP (DP). In these models, novel indices viz., (i) rainfall departure and irrigation index (RDII) and (ii) physical and socio-economic index (PSEI), were used as predictor variables. These models, with R2 (0.71-0.75) and RMSE of 11.8-14.2(< SD of observed data), hold promise for advance estimation of production loss in states, useful for regional-level planning by the Government of India, and testing them in other countries.

Refined Allocation of Water Resources in Pishihang Irrigation Area by Joint Utilization of Multiple Water Sources

Refined allocation of water resources is an important means of sustainable water resources utilization. Based on General Water Allocation and Simulation (GWAS), this study uses a Geographic Information System (GIS) to construct spatial topological relationships. A fairness optimal minimum was set as the objective function. Total quantity control, water supply potential, and quality-divided water supply were set as constraint conditions. Considering the dynamic mutual-feedback relationship between the middle-lower-reaches reservoir and the upstream reservoir, this study refines the allocation of water resources combined with the characteristics of “long cane knots melons” in the Pishihang irrigation area. Results showed that at 50%, 80%, and 90% frequencies in the base year, 2025, and 2035, respectively, the water deficient ratio is 0. For continuous drought years at 90% frequency, all water users are faced with different degrees of water shortage. In water source structures, water diversion in the irrigated area is the largest, followed by local surface water; reclaimed water and shallow groundwater are used as supplements. In the case of consecutive drought years, the water shortage degree can be reduced through rational development of local water and additional external water transfer. The model has thus been well applied. This study provides a more accurate method for optimizing water resources allocation.

Coupled biophysical and decision-making processes in grassland systems in East African savannahs – A modelling framework

Increasing livestock densities on limited grazing areas in African savannahs lead to resource degradation through overgrazing, aggravated by drought. Assessing herd management strategies over longer periods at landscape scale is important to propose options for sustainable land use. This requires an understanding of processes related to hydrology, nutrient cycling, herd movement, pasture degradation, and animal resilience that involve dynamic soil-plant-animal interactions and human decisions about stocking rates, livestock purchases and sales.We present the coupled model system MPMAS-LUCIA-LIVSIM (MLL), the combination of a spatially explicit agent-based model for human decision-making (MPMAS), a spatially distributed landscape model for water flows, nutrient cycles and plant growth (LUCIA), and a herd model (LIVSIM) representing grazing, body weight, nutrition and excreta of individual animals. MLL represents daily vegetation growth in response to grazing and organic inputs, monthly animal performance influenced by forage availability and quality, and herders’ management in response to resource status. New modules for selective grazing, resprouting of pasture, herd movement and model coupling were developed for MLL.The test case of a pastoral system in the Ethiopian Borana region demonstrates the capabilities of MLL to simulate key soil-plant-animal-human interactions under climate-related management scenarios with varying access to grazing land, changing cattle prices and different spending / saving behaviour of herders. 20-year simulations showed the negative impact of consecutive drought years on vegetation biomass, on herd development and movement and how reserving grazing areas for dry seasons could mitigate overgrazing and improve income. Seasonality and drought response of vegetation growth, selective grazing of different plant parts, resprouting after grazing, calving intervals, milk yields and lactation in response to forage supply and quality as well as herder reactions to shocks were plausibly represented.Building upon this successful proof-of-concept, MLL can be used to identify robust management options for improved grazing systems in savannahs in follow-up research.

The ambivalent effect of biocrusts on evaporation: Can the contradictory conclusions be explained? A review

The scholarship on evaporation has yet to fully comprehend the effects of biocrusts on evaporation. This lacuna profoundly impacts our understanding regarding the hydrological role played by biocrusts in shaping arid and semiarid ecosystems. While most scholars maintain that biocrusts decrease evaporation, playing therefore a cardinal positive role in preserving soil moisture and promoting plant growth and survival, there are other scholars that claim the opposite, i.e., that biocrusts increase surface and subsurface temperatures, increase evaporation, subsequently negatively affecting the growth and survival of vascular plants. Our paper elucidates the factors leading to these controversial conclusions. We maintain that while the higher water-holding capacity of the crust (resulting from higher extracellular polymeric substances, organic matter and dust) may retain higher amount of water soon after the wetting event (commonly for 1–2 d), increased evaporation takes place shortly afterwards due to the lower albedo of the crust and the subsequent increase in surface and subsurface temperatures. This may explain reports on low above-ground biomass of plants from crusted surfaces in the Negev, Gurbantunggut, and the Australian deserts. It may also explain early mortality, low above-ground biomass and low fecundity of annual plants on crusted surfaces in the Negev, as well as lower water potential and higher mortality of perennial plants on crusted surfaces following consecutive drought years in the Negev.

Drought analysis and management for Tamil Nadu: Science-stakeholder-policy linkage

The complex and multi-dimensional nature of droughts in Tamil Nadu state and its impact on agricultural sector and farming community requires a thorough analysis for developing short and long– term adaptation and mitigation measures with institutional arrangement and policy support. In the present investigation, drought analysis was made for Tamil Nadu state using 148 years (1871 – 2018) monthly rainfall data obtained at district scale from India Meteorological Department (IMD) and Tamil Nadu Agricultural University by employing various drought indices. Larger co-efficient of variation (139 and 149 %) during the major growing seasons (Southwest and Northeast monsoon)evidenced high undependability of rainfall over Tamil Nadu. Drought Index (DI) analysis indicated a 51 per cent drought years in SWM and 48 per cent in NEM season, while Standardized Precipitation Index (SPI) exhibited 43 and 48 per cent of drought years in SWM and NEM respectively, indicating occurrence of drought once in every four years. More number of Consecutive Drought years (CDY) posed serious impacts on food production and livelihoods. Drought management framework as well as input for designing drought policy for Tamil Nadu.

Variability of extreme weather events and its impact on crop yield in Bundelkhand Agroclimatic zone of Madhya Pradesh

The Bundelkhand Agroclimatic Zone of Madhya Pradesh has witnessed many extreme weather events in recent decades like excessive hotness, dryness, coldness and number of consecutive drought years. Drought and water scarcity are the major resource limiting factors of this zone. There was sharp increase in numbers of hot days during last decade (2001-10) in Chhatarpur and Datia districts. The numbers of heavy rainfall days sharply decreased at Tikamgarh and Chhatarpur districts while frost days increased in Datia during last decade. The micro level variability of drought was much higher than the temporal scale variability. The occurrence of drought at micro level in the recent decade was much higher. The frequent occurrence of drought during recent past had increased the soybean and paddy yield variability in this zone. This paper attempts to present impact of variability of extreme weather events on paddy and soybean yield and also rural livelihood. The paddy and soybean yield were normally affected by number of heavy rainy days and number of rainy days. The number of heavy rainy days greater than equal to 6 days in Tikamgarh, 7 days in Chhatarpur per year were may be required for sustainable paddy production. It is observed that in those districts where the temporal variation in number of rainy days is decreasing, the decrease in number of rainy days below 5 days per year was crucial for sustainable yield. Whereas in the districts where little temporal variation in number of rainy days observed, a particular number of heavy rainy days is not necessary for adequate crop yield. In Datia and Chhatarpur district, the animal discomfort days increased over the decades.

A Research of the Section Layout of the Second Phase of the Eastern Route of South-to-North Water Diversion Project: from Hongze Lake to Luoma Lake

The south-to-north water diversion project is a major strategic project in China to construct the overall pattern of the water resources allocation according to the principle of “four horizontal and three vertical, north-south allocation and east-west mutual aid”. On the one hand, the first phase of the eastern route of the south-to-north water diversion project started construction in December 2002 and was completed in November 2013. After completion, it has played an important role in alleviating the contradiction between supply and demand of water resources due to consecutive drought years in Shandong Province, especially in the Shandong Peninsula, which has ensured the economic and social development and improved the ecological environment in recent years. On the other hand, the second phase of the eastern route will further improve the allocation of water resources in China, ensure the security of water supply in important areas such as Beijing and Tianjin, and further improve the water ecological environment along the route. While the section from Hongze Lake to Luoma Lake is listed as the second section of the eastern route of this project (among 11 sections in total), the water layout, officially approved in the early stage, contradicts the one recommended by Jiangsu Province. On this basis, the key to ensure the smooth implementation of the project of this section is to study its scheme of water distribution in combination with the regional water system, coordinate the functions of flood control, drainage, water supply, navigation and ecology, and put forward an economical, reasonable and technically feasible scheme of water distribution.

Covid-19 impact on Zimbabwean agricultural supply chains and markets: A sustainable livelihoods perspective

The purpose of the article is to analyse the impact of COVID-19 on the agricultural supply chains and markets in Zimbabwe and subsequent effect on livelihoods. The research methodology that was applied is a systematic literature survey anchored on inductive research approach. This article is based on the systematic review of secondary data sources, such as journals, policy reports, as well as reports from national and international organizations. The review involved a predetermined and comprehensive approach of searching, analyzing and synthesizing extant literature on agricultural supply chains. In general, the pandemic has affected the whole supply chain from the food production systems and input supply, the storage and distribution, processing and packaging as well as the retail and marketing aspect. The research showed that the COVID-19 pandemic severely threatens an already critical food security situation arising mainly from the prevailing poor macroeconomic conditions and consecutive years of drought in Zimbabwe. This has led to a higher than previously anticipated food insecure population, especially in urban centers. Over 70% of the workers are self-employed and a vast majority operate in the informal sector. The informally employed represent a significant breadwinner constituency, whose dependents comprise vulnerable sections of the populace. The restrictions on mobility and the closure of borders meant immediate loss of employment and income. The study revisited the previous viruses such as Ebola to extrapolate though marginally, the implications of the COVID-19 pandemic. Using secondary sources and the general agriculture supply chain to guide understanding, the findings show that unless measures are put in place to safeguard farmers especially smallholder activities in Zimbabwe, COVID-19 has the potential to reproduce the same catastrophic implications created by Ebola in West Africa countries where peasant food systems where shattered and livelihoods strategies maimed.

Drought Characterization Over Periyar Vaigai Command Area in Tamil Nadu

India encountered numerous drought years in the decades. It is a matter of concern with increased frequency as well as intensity, mainly due to factors related to changing climate in recent years. In India livelihoods of more than 75% of the population are directly or indirectly dependent on agriculture sectors. The strong and recurrent link between drought and farmer's livelihoods has highlighted the importance to understand the drought scenario of a place for designing coping strategies. To address the issue, this paper was formulated to characterize the drought scenario over Periyar Vaigai Command (PVC) area. To summarize the results, the locations Edayapatti and Periaaruvi had the highest number of annual drought occurrence (8) while the location Madurai airport had the lowest (2) based on the analysis of 30 years. On comparing the monsoons, there are no wide variations in drought characteristics between Southwest monsoon (SWM) and Northeast monsoon (NEM). Anomalies in rainfall during the monsoon seasons were studied through SPI, consecutive drought years were well presented through SPI, which gives relevant information for crop planning. In both the monsoons, the locations Viraganur, Pulipatti and Usilampatti witness consecutive droughts. The highest of three consecutive years (1999, 2000 and 2001) were witnessed in Usilampatti during the major NEM season.

Drought-Induced Reductions and Limited Recovery in the Radial Growth, Transpiration, and Canopy Stomatal Conductance of Mongolian Scots Pine (Pinus sylvestris var. mongolica Litv): A Five-Year Observation

Determining plant–water relationships in response to drought events can provide important information about the adaptation of trees to climate change. The Mongolian Scots pine (Pinus sylvestris var. mongolica Litv), as one of the major tree species to control soil loss and desertification in northern China, has experienced severe degradation in recent decades. Here, we aimed to examine the impacts of a two-year consecutive drought and another year of drought on the radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pine over a five-year period, especially in terms of its recovery after drought. The study period during 2013–2017 consisted of a ‘normal’ year, a ‘dry year’, a ‘very dry’ year, a ‘wet’ year, and a ‘dry’ year, according to annual precipitation and soil moisture conditions. Based on measurements of the sap flow and diameters at breast height of 11 sample trees as well as the concurrent environmental factors, we quantified the reductions in tree radial growth, transpiration, and canopy stomatal conductance during the drought development as well as their recovery after the drought. The results showed that the tree radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pines decreased by 33.8%, 51.9%, and 51.5%, respectively, due to the two consecutive years of drought. Moreover, these reductions did not fully recover after the two-year drought was relieved. The minimum difference of these parameters between before and after the two-year consecutive drought period was 8.5% in tree radial growth, 45.1% in transpiration levels, and 42.4% in canopy stomatal conductance. We concluded that the two consecutive years of drought resulted in not only large reductions in tree radial growth and water use, but also their lagged and limited recoveries after drought. The study also highlighted the limited resilience of Mongolian Scots pine trees to prolonged drought in semi-arid sandy environmental conditions.

Hydroclimate Variability in Snow-Fed River Systems: Local Water Managers’ Perspectives on Adapting to the New Normal

AbstractBetween water years 2012 and 2017, the Truckee–Carson river system in the western United States experienced both historic-low and record-high Sierra Nevada snowpack, anomalously warm temperatures, and winter and spring flooding. As part of an ongoing collaborative modeling research program in the river system, researchers conduct annual interviews with key local water managers to characterize local climate adaptation strategies and implementation barriers, and identify science information needs to prioritize ongoing research activities. This article presents new findings from a third wave of interviews conducted with the same water managers following the historic 2017 wet year. Comparison of these data suggests that managers increased their adaptation efforts described during previous consecutive drought years (2015 and 2016). In 2017, comparatively fewer managers described climate uncertainty as an implementation barrier, exemplifying recent hydroclimate variability as the “new normal” climate for which they should plan. An assessment of recent conditions reveals that recent water years bound historical observations and are consistent with estimated paleoclimate extremes in terms of magnitude, but not persistence, of both dry and wet conditions. Comparison to projected future climate conditions affirms managers’ perspectives that increased hydroclimate variability, inclusive of drought and flood extremes, defines the new normal climate anticipated for the region. To support long-term adaptation planning, managers requested that researchers prioritize simulations of alternative water management strategies that account for nonstationary climate patterns and quantify implications system-wide. This article illustrates how interdisciplinary research that integrates local knowledge with applied climate science research can support adaptive water management in snow-fed river systems.

MAKING CITIES WATER-WISE AND CLIMATE-RESILIENT — LESSONS AND EXPERIENCE FROM THE CAPE TOWN DROUGHT

Half of humanity now lives in cities and the net inflow of population into cities will continue. Among all challenges faced by cities, the provisioning for water and sanitation is probably the most pressing one. From 2017 to 2018, the city of Cape Town in South Africa frequently made itself media headlines around the world, in many languages, for its severe water shortage due to consecutive years of drought that later resulted in a water crisis. Fortunately, the potential “Day Zero” when the city would run out of water, did not arrive. However, the crisis exposed a lack of resilience in the city’s water supply system in the face of ongoing climate change and a governance gap for climate adaptation. Many cities, especially those in the Global South, can learn from Cape Town’s experience and lessons on how to enhance governance to become more climate-resilient. Mark New and Gina Ziervogel, the interviewees, have been devoting themselves to studying about the Cape Town drought, and working on establishing the Cape Town Drought Response Learning Initiative. In this article, they analyzed the influence of climate change on Cape Town drought and the water supply system, and suggested effective methods to address and prevent the drought and water shortage. Ziervogel briefly described her adaptive and water-sensitive city framework while both of them revealed the role of Cape Town Drought Response Learning Initiative in making Cape Town more resilient.