Joint evolution of irrigation, the water cycle and water resources under a strong climate change scenario from 1950 to 2100 in the IPSL-CM6

<p>The growing water extraction due to the economic development and population growth has caused over-utilization of water resources worldwide, especially in semiarid regions. In these regions, the sustainable water availability has often been sought and maintained by managing land, but it is highly uncertain in future climate conditions. Besides, prediction of water availability in such region is still challenging due to non-stationary rainfall-runoff relationship caused by intensive human interferences and poor ET simulation by hydrological models. Therefore, accurate estimation and maintaining of sustainable water availability under future climate conditions are important for the ecological conservation and social development of semiarid regions. In this study, impacts of land use and climate changes on vegetation dynamics (canopy LAI) and water cycle (ET and runoff) of the Xiong’an New Area (XNA) are investigated using an ecohydrological model (i.e., WAVES). The XNA, a typical semiarid region located in North China, is expected to need more water in order to increase the vegetation coverage from 10% to 40% by 2035. The WAVES model is chosen because it can simulate ET well by coupling water-carbon-heat. Here, water use (ET) and water yield (runoff) of three typical ecosystems (i.e., cropland, grassland and forestland) in different future periods (i.e., near-future: 2030s (2021-2040), mid-future: 2050s (2041-2060) and far-future: 2080s (2061-2100)) are assessed using projected future climate forcing from 18 GCMs under three RCPs (i.e., RCP2.6, RCP4.5 and RCP8.5). Projected precipitation (<em>P</em>) and air temperature (<em>T<sub>a</sub></em>) indicate the XNA will become warmer and wetter in the future. The WAVES model is capable to simulate the ecohydrological process well in the XNA with NSE ≥ 0.62, R<sup>2</sup> ≥ 0.65, RMSE ≤ 0.86 in LAI and NSE ≥ 0.61, R<sup>2</sup> ≥ 0.66, RMSE ≤ 0.71 mm·d<sup>-1</sup> in ET. During the baseline period of 1982-2012, modeling results show that the forested land evaporates more water (32 mm a<sup>−</sup><sup>1</sup>) than cropland while grassland use almost same water as cropland. Under future climate conditions, both cropland and the grassland will have more water use and water yield due to increased precipitation and suppressed vegetation growth due to warming. Forested land will use more than 20% water (76 mm a<sup>−</sup><sup>1</sup>) compared with that during the baseline period in the XNA, but it will generate more than 10% (12 mm a<sup>−</sup><sup>1</sup>) water yield in the 2050s and 2080s under RCP4.5 and RCP8.5 due to greater increases in precipitation. For the purpose of land management, it is recommended to plant crop or grass in the near-future and to plant forest in the mid-future and far-future to expand vegetation coverage in the XNA. This study highlights that both climate change and land management are of critical importance for sustaining water yield in semiarid regions with over-utilized water resources.</p>

BackgroundRice is a major contributor to anthropogenic greenhouse gas (GHG) emissions, primarily methane, and at the same time will be negatively impacted by regional climate changes. Identifying rice management interventions to reduce methane emissions while improving productivity is, therefore, critical for climate change mitigation, adaptation, and food security. However, it can be challenging to conduct multivariate assessments of rice interventions in the field owing to the intensiveness of data collection and/or the challenges in testing long-term changes in meteorological and climate conditions. Process-based modeling, evaluated against site-based data, provides an entry point for evaluating the impacts of climate change on rice systems and assessing the impacts, co-benefits, and trade-offs of interventions under historical and future climate conditions.MethodsWe leverage existing site-based management data to model combined rice yields, methane emissions, and water productivity using a suite of process-based coupled crop-soil model experiments for 83 growing sites across the Red River Delta, Vietnam. We test three rice management interventions with our coupled crop-soil model, characterized by Alternate Wetting and Drying (AWD) water management and other principles representing the System of Rice Intensification (SRI). Our simulations are forced with historical as well as future climate conditions, represented by five Earth System Models for a high-emission climate scenario centered on the year 2050. We evaluate the efficacy of these interventions for combined climate change mitigation and adaptation under historical and future climate change.ResultsTwo SRI interventions significantly increased yields (one by over 50%) under historical climate conditions while also reducing (or not increasing) methane emissions. These interventions also increase yields under future climate conditions relative to baseline management practices, although climate change decreases absolute yields across all management practices. Generally, where yield improved, so did crop water-use efficiency. However, impacts on methane emissions were mixed across the sites under future climate conditions. Two of the interventions resulted in increased methane emissions, depending on the baseline management point of comparison. Nevertheless, one intervention reduced (or did not significantly increase) methane under both historical and future climate conditions and relative to all baseline management systems, although there was considerable variation across five selected climate models.ConclusionsSRI management principles combined with high-yielding varieties, implemented for site-specific conditions, can serve climate change adaptation and mitigation goals, although the magnitude of future climate changes, particularly warming, may reduce the efficacy of these interventions with respect to methane reductions. Future work should better bracket important sensitivities of coupled crop-soil models and disentangle which management and climate factors drive the responses shown. Furthermore, future analyses that integrate these findings into socio-economic assessment can better inform if and how SRI/AWD can potentially benefit farmer livelihoods now and in the future, which will be critical to the adoption and scaling of these management principles.

Chapter 1 - Water Resources Modeling and Prospective Evaluation in the Indus River Under Present and Prospective Climate Change

Radley Horton,1,a Daniel Bader,1,a Yochanan Kushnir,2 Christopher Little,3 Reginald Blake,4 and Cynthia Rosenzweig5 1Columbia University Center for Climate Systems Research, New York, NY. 2Ocean and Climate Physics Department, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY. 3Atmospheric and Environmental Research, Lexington, MA. 4Physics Department, New York City College of Technology, CUNY, Brooklyn, NY. 5Climate Impacts Group, NASA Goddard Institute for Space Studies; Center for Climate Systems Research, Columbia University Earth Institute, New York, NY

The Schuylkill River watershed located in southeastern Pennsylvania drains approximately 2,000 square miles and provides services to nearly 1.5 million residents. The water resources provide many benefits and services to the environment, economy and society in the region. The impact of changing climate and land use conditions on these resources has the potential of majorly affecting the day-to-day functioning of the watershed. Water management policies are designed to ensure the availability of water resources to meet the water demand in a region based on historical data. As these policies are based on historical information, it is important to assess the effects of changing climate on water resources in the future, especially with the intensification of climate change. This, coupled with changing land use conditions, could alter the quantity and quality of water resources significantly. The effects of climate and land use change on the water resources were quantified by estimating the runoff produced and the baseflow available in the region under simulated future conditions. The runoff was calculated using the Curve Number method by incorporating the effects of land use and hydrologic soil conditions present in the region. The baseflow was deduced by integrating the effects of the precipitation, potential evapotranspiration and soil moisture in the region. The land use change conditions were projected based on historical change in impervious conditions and future demand projections. The projected land use conditions were used to calculate the Curve Number for the period of 2020-2040. The climate change conditions and hydrologic parameters used for the calculations were derived from the Localized Constructed Analog (LOCA) data and the Bias-Correction Spatial Disaggregation (BCSD) data respectively.

Catchments in the future North: interdisciplinary science for sustainable management in the 21^st Century

Harmonizing manure and mineral fertilizers can mitigate the impact of climate change on crop yields

علاوه بر تغییر‌اقلیم، تغییر‌کاربری‌اراضی به عنوان یک عامل جانبی اثرات مهمی بر سیلاب دارد. لذا پیش-بینی اثر این دو پارامتر بر وضعیت سیلاب دهه‌های آتی، راهگشای مقابله با این پدیده خواهد بود. هدف از مطالعه حاضر پیش‌بینی وضعیت هیدرولوژیکی حوزه آبخیز اسکندری در دهه آتی تحت اثر تغییر‌اقلیم و تغییر‌کاربری‌اراضی می‌باشد. جهت بررسی تغییرات اقلیمی دهه 2020، برونداد مدل HadCM3 تحت سناریوهای A2 و B1 توسط مدل LARS-WG ریزمقیاس گردید. پس از بررسی تغییرات کاربری-اراضی گذشته، دو سناریو جهت پیش‌بینی تغییرات آن در آینده طراحی شد. در انتها با تغییر هایتوگراف بارش و کاربری‌اراضی در مدلHEC-HMS که برای دوره گذشته کالیبره و اعتبارسنجی شده، اثر تغییر اقلیم و کاربری اراضی بر سیلاب منطقه مطالعاتی مورد بررسی قرار گرفته شد. نتایج نشان دهنده افزایش 2/7 تا 9/10 درصدی بارش متوسط سالانه دهه 2020 می‌باشد. افزایش توأمان دمای حداقل و حداکثر منطقه مطالعاتی در تمامی ماه‌ها موجب افزایش 82/0 تا 02/1 درجه سانتی‌گرادی دمای متوسط سالانه خواهد شد. افزایش دبی اوج و حجم سیلاب در ماه‌های مارس، اکتبر و فوریه و کاهش آن در ماه آوریل پیش بینی شده است. به طوری که در صورت تغییر‌کاربری‌اراضی همراه با تغییر‌اقلیم این افزایش شدیدتر خواهد بود.

Co-development of East African regional water scenarios for 2050

Global Climate Changes - Sources and Impacts on the Water Cycle.- Climate Change and Water Cycle - Some Lessons from the Geological Past.- Climate Change and the Water Cycle - Some Information Concerning Precipitation Trends.- Moroccan Climate in the Present and Future: Combined View from Observational Data and Regional Climate Scenarios.- Impact of Climate Change on Water Availability in.- Climatic Changes in Lebanon, Predicting Uncertain Precipitation Events - Do Climatic Cycles Exist?.- Impact of Climate Change on Water Resources.- Water Resources Management in the Middle East under Aspects of Climatic Changes.- Virtual Water Trade as an Adaptation Demand Management of Climate Change Impact on Water Resources in the Middle East.- The Impacts of Climate Change on Water Resources in Jordan.- Impact of Climate Change on Water Resources of Lebanon: Indications of Hydrological Droughts.- The Impact of Global Warming on the Water Resources of the Middle East: Past, Present, and Future.- Decadal Precipitation Variances and Reservoir Inflow in the Semi-Arid Upper Draa Basin (South- Eastern Morocco).- Management Options for a Sustainable Groundwater Use in the Middle Draa Oases under the Pressure of Climatic Changes.- Water Resources and Water Management.- A Decision Support System (DSS) for Water Resources Management, - Design and Results from a Pilot Study in Syria.- Management Strategies of Water Resources in the Arid Zone of South-Eastern Morocco.- The Role of Groundwater During Drought in Tunisia.- The Evolution of Groundwater Exploration Methods in the Moroccan Oases through History, and Managing Ecological Risk of their Present Pollution.- Investigating Unconsolidated Aquifers in an Arid Environment - A Case Study from the Lower Jordan Valley/Jordan.- Water Resources Protection Efforts in Jordan and their Contribution to a Sustainable Water Resources Management.- Model Investigations on the Groundwater System in Jordan - A Contribution to the Resources Management (National Water Master Plan).- Seawater Intrusion in Greater Beirut, Lebanon.- Long Term (1970 - 2001) Eco-Hydrological Processes in Lake Kinneret and its Watershed.- Transfer of the Concepts of the European Water Framework Directive to Arid and Semiarid Regions.- Seal Formation Effects on Soil Infiltration and Runoff in Arid and Semiarid Regions under Rainfall and Sprinkler Irrigation Conditions.- Restoring the Shrinking Dead Sea - The Environmental Imperative -.- Groundwater in the Shallow Aquifer of the Jericho Area, Jordan Valley - Noble Gas Evidence for Different Sources of Salinization.- The Interaction of Population Dynamics and Transformations in Water Supply Systems in the Jordan River Basin.

Triangle of Environment, Water and Energy: A Sociological Appraisal

Irrigation vulnerability assessment on agricultural water supply risk for adaptive management of climate change in South Korea

The Intergovernmental Panel on Climate Change (IPCC) fourth assessment report confirmed that climate change is unequivocal. It is coming to us faster with larger impacts and bigger risks than even most climate scientists expected as recently as a few years ago. One particular worry is the disastrous consequence to agriculture and food security sectors in many parts of the world, particularly in developing countries. Adaptation is the only option to reduce the impacts of climate change on the agriculture sector. However, before planning adaptation policy or strategies to climate change, it is important to assess the impacts of climate change at regional and local scale. In this study the impacts of climate change on rain-fed maize (Zea Mays) production in the southern and western highlands sub-agro ecological zones of Tanzania are evaluated. High resolution climate simulations from the Coordinated Regional Climate Downscaling Experiment _Regional Climate Models (CORDEX_RCMs) were used as input into the Decision Support System for Agro-technological Transfer (DSSAT) to simulate maize yields in the historical climate condition (1971-2000), current (2010-2039), mid (2040-2069) and end (2070-2099) centuries. Daily rainfall, solar radiations, minimum and maximum temperatures for the historical (1971-2000) climate condition and future climate conditions (2010-2099) under two Representative Concentration Pathways (RCPs) RCP4.5 and RCP 8.5 were used to drive DSSAT. The impacts of climate change were assessed by comparing the average maize yields in historical climate condition against the average of simulated maize yields in the current, mid and end centuries under RCP4.5 and RCP8.5. Results indicated that maize yields will decline in future climate condition. High decreases in maize yield over the Southern and southwestern sub ecological zones are expected in the end centuries under RCP 8.5. The main reason for decline in maize yields during future climate is the increase in temperatures that shorten the length of growing seasons. Therefore it is recommended that more studies need to be carried out that addresses on how farmers may adapt the impacts of projected increase in temperatures on maize crop production.

The study investigates the interplay of land use dynamics and climate change on the hydrological regime of the Ravi River using a comprehensive approach integrating Geographic Information System (GIS), remote sensing, and hydrological modeling at the catchment scale. Employing the Soil and Water Assessment Tool (SWAT) model, simulations were conducted to evaluate the hydrological response of the Ravi River to both current conditions and projected future scenarios of land use and climate change. This study differs from previous ones by simulating future land use and climate scenarios, offering a solid framework for understanding their impact on river flow dynamics. Model calibration and validation were performed for distinct periods (1999–2002 and 2003–2005), yielding satisfactory performance indicators (NSE, R2, PBIAS = 0.85, 0.83, and 10.01 in calibration and 0.87, 0.89, and 7.2 in validation). Through supervised classification techniques on Landsat imagery and TerrSet modeling, current and future land use maps were generated, revealing a notable increase in built-up areas from 1990 to 2020 and projections indicating further expansion by 31.7% from 2020 to 2100. Climate change projections under different socioeconomic pathways (SSP2 and SSP5) were derived for precipitation and temperature, with statistical downscaling applied using the CMhyd model. Results suggest substantial increases in precipitation (10.9 − 14.9%) and temperature (12.2 − 15.9%) across the SSP scenarios by the end of the century. Two scenarios, considering future climate conditions with current and future land use patterns, were analyzed to understand their combined impact on hydrological responses. In both scenarios, inflows to the Ravi River are projected to rise significantly (19.4 − 28.4%) from 2016 to 2100, indicating a considerable alteration in seasonal flow patterns. Additionally, historical data indicate a concerning trend of annual groundwater depth decline (0.8 m/year) from 1996 to 2020, attributed to land use and climate changes. The findings underscore the urgency for planners and managers to incorporate climate and land cover considerations into their strategies, given the potential implications for water resource management and environmental sustainability.

Water scarcity is arguably a pressing issue for the 21st century in Mediterranean areas, due to limited water resources, expansion of irrigated area to sustain food security and climate change. Water extraction for agriculture sector account about to 70% of global water use, and this demand peaks to 80% of total water withdrawal in several southern Mediterranean countries. In this study, the impact of climate change on evapotranspiration demand, crop water requirements, and crop yield losses due to water shortage, were assessed by using the Simulation of Evapotranspiration of Applied Water (SIMETAW_GIS) model. This crop-soil-water model was implemented over the Sardinia island, a region with a typical Mediterranean climate and agriculture characteristics, assuming impact of climate change for a whole range of relevant Mediterranean crops (Wheat, Barley, Sugar beet, Potato, Lentil, Almond, Maize, Wine Grape, Table Grape, Tomato, Rice, Artichoke, Alfalfa, Olives, Improved Pasture and Orange). Under present analysis, daily climate data from five Earth System Models dynamically downscaled to a spatial resolution of 0.11-degrees (~11 km) from the  EURO-CORDEX project domain and available from the Copernicus Climate Data service (https://climate.copernicus.eu/) were retrieved and ensembled. The impact of climate change on crop water requirements was evaluated under historical (1976-2005) and future (2036-2065) climate conditions following different Representative Concentration Pathways (RCPs: 2.6, 4.5 and 8.5), representing alternative mitigation policies and future emission scenarios. In the Sardinia region, results show a variegated increase of crop water demand between future (2036-2065) and historical conditions (1976-2005) for different crops, which may pose a challenge for water resource management, especially considering water use conflicts among different sectors. On average wheat and barley will foresee the most significant increase of crop water requirements, ranging on average by 12 to 14% under different RCPs. Other crops (e.g. almond, maize, wine grape, and pasture) are projected to foresee still significant increases of crop water demand, varying between 4-8%.  This work provides information that can support farmers and decision managers to evaluate climate change adaptation strategies linked to different cropping patterns to increase use efficiency of water resources for a more sustainable agriculture production under climate change.