TABLE 6. Optimized demand restriction triggers, in % usable storage. Current demand re- striction triggers are presented as a single value, termed "MWCOG", while optimized results for the 2040 Demand and Sedimentation case "2040" and the CSIRO A2 2070-2099 case, "2070", are presented as a range across all non-dominated solutions.
Integrated watershed management provides an important governing framework for anticipating and achieving success- ful adaptation measures across socioeconomic, environmen- tal, and administrative systems. To be effective, integrated approaches must occur at the appropriate scale or scales needed to facilitate effective actions for specific outcomes, and they must be based on strong linkages among monitoring, research, and management as climate varies and changes. A more comprehensive mode of operation that includes water- shed management (given interbasin transfers and so forth) is integrated waterresources management. Integrated water- management strategies include capturing social and individual risk perception, reshaping planning processes, coordinating land and waterresources management, recognizing water- quantity and water-quality linkages, increasing conjunctive use of surface water and ground water, improving techniques to manage demand and conserve water, protecting and restoring natural systems, and learning through adaptive management experiments, including consideration of climatechange. In addition, integrated strategies explicitly address impediments to the flow of information across the nodes of action (agen- cies, States, tribes, communities, and the private sector) and focus on decision quality as well as acceptability (Pulwarty, 2003). Institutional efforts to reduce conflict can also help to achieve desired goals. A fully integrated approach is not always needed, but rather the appropriate scale for integration
The changes in precipitation and temperature are the sole key to the changes in the availability of waterresources including surface and groundwater (Beare and Heaney, 2002). For example, Pungwe River Basin in Zimbabwe and Mozambique, the river flow and water availability have decreased due to a decreased in precipitation especially during the end of the dry season for about 50 to 60 percent which could led to severe other consequences (Anderson et al., 2011). Meanwhile at Mediterranean watershed, based on combined result from both Sado and Guadiana river basins, it can be noted that the precipitation and temperature, projected by the global climate models for the end of the twenty-first century, point towards greater reduction in the water availability (Mourato et al., 2015). Climatechange also has the potential to impose additional pressures on water availability and waterdemand in Africa (Bates et al., 2008).
Since the river basin is involved in the generation of hydropower and in order to mitigate and/ or improve the negative projected effects on this generation of energy, several scenarios are created with various strategies, which are then used to determine the influence of these strategies on the unmet demand (UD) in the region, considering specifically the most critical months of the year from February to April. The proposed strategy is simulated by generating a new demand site in the study region called “pumping”, whose purpose is to extract water from a source downstream from the dam and supply that water upstream or at the dam site (see Fig. 1).
The above problems can be mitigated by applying integrated waterresources management. Climatechange has major impact on the world’s freshwater resources quality and water management. Increases in water temperature and changes in the timing and amount of runoff are likely to produce unfavorable changes in surface water quality, which will in turn affect human and ecosystem health. The threats posed by climatechange will serve as an additional stressor to many already degraded water dependent systems, particularly those in developing countries and all sectors of the economy and more so in agriculture and hence a threat to food security. In Kenya, for the county governments which are within the same river basin, there is need for the formulation of a shared water management vision by the respective counties so as to have counties where there is an equitable and sustainable use and management of waterresources in agricultural activities, poverty alleviation, socio economic development, regional cooperation, and sustainable environmental quality management.
Usangu catchment, a part of the Rufiji Drainage Basin, is important for rice production in Tanzania. It pro- duces more than 30% of the country’s rice and supports over 30,000 rice-producing households on approxi- mately 45,000 ha of irrigated land (SMUWC 2001). Rice and onions have captured good market price in the recent years which, in turn has brought a huge influx of Tanzanians into the catchment area to grow these crops. As a result, forest and wetlands along the rivers including the Ndembera river are converted into small irrigated farms. Kashaigili (2008) showed that there is a clear linkage between land use/cover changes and the changes in the hydrological regime for the Usangu wet- lands and the Great Ruaha river in the Usangu catch- ment. It is therefore important to assess the changes in water balance and river discharge resulting from the land use/cover changes taking place in the Ndembera river watershed.
The Intergovernmental Panel on ClimateChange (IPCC) report indicates that the warming of the climate system is unequivocal as is now proved by observations of increases in global mean air temperature (IPCC, 2013). The report emphasizes on decrease in precipitation and moderate climatechange in the entire Mediterranean basin including Morocco. In a scenario of moderate climatechange, the poor and landless agricultural based population of rural areas is the most vulnerable to these climatic changes (FAO/IFAD, 2006). These moderate changes affected the demand and supply chain of food and water, resulted into potential catastrophic environmental and socio-economic consequences (Imhoff and Bounoua, 2006), such as water scarcity will increase due to decrease in precipitation and high demand of water of ever increasing population. The patterns of precipitation (235 to 380 mm) showed maximum area under aridity condition with strongly affected by climatechange and variability (Figure 2). During last decade, the variable temperature and decrease in precipitation heavily influenced the agriculture (Tanouti and Molle, 2014; MEMEE, 2015). In fact, the plain in our study region is an agricultural area of 52,000 hectares. Thus, a growing North-South gradient of precipitation was noted (Figure 2).
Estimates of consumptive use of water in the basin were reported in terms of depletions and deliveries. Some users are guaranteed, by law, minimum deliveries. Deliveries of water from the upper to the lower basin fall below legal requirements 23% of the time in the base case. If average flows drop only five percent, this frequency rises to 41%. Under the Colorado River Simulation System operating assumptions, the scheduled deliveries of water to the Metropolitan Water District of Southern California are met in all years under all scenarios because of their higher water right. Annual deliveries to the Central Arizona Project, which has a more junior right, meet or exceed scheduled deliveries only 40% of the time in the base case and fall to their minimum level in 50% of the years when long- term runoff drops only five percent. Table 12 summarizes the percent frequency with which scheduled deliveries to MWD, CAP, and Mexico are met or exceeded. Deliveries to Mexico fall under the level specified by international treaty when long-term average runoff decreases by 10% or more. Potential changes in waterdemand due to climatechange were not addressed by the study, but would further complicate basin management. Lettenmaier et al. (1999) conducted a broad assessment of the sensitivity of six major U.S. water resource systems to climatechange and evaluated the performance of multiple-use systems. These studies applied a range of transient GCM scenarios and evaluated the effects on end users of water. Six systems were studied in all: two very large river basins (the Columbia and Missouri), two moderate size basins (the Savannah and Apalachicola- Chattahoochee-Flint (ACF)); and two urban water-supply systems (Boston and Tacoma). For each system, several indicators were evaluated, including system reliability (defined as the percentage of time the system operates without failure), the system resiliency (defined as the ability of the system to recover from a failure), and the system vulnerability (defined as the average severity of failure).
The supply enhancement by transferring water from Yellow River will cause a threat to ecological environment and water pollution. On the other hand, waterdemand management is limited and challenged by the industrial scale, and may affect the rate of economic growth. However, it will reduce the gap between water supply and demand. It is envisaged that the quantities of wastewater re-use will increase to provide additional supplies. Therefore, it can be remarked that though each of the three management systems have their own pros and cons, it is possible to achieve a better balance between water supply and demand if a waterdemand management option is adopted. Different waterdemand management options, such as water conservation, growing public water-saving awareness, improving efficiencies within the pro- duction process and agricultural consumption, controlling the consumer water price mecha- nism, etc. can help to achieve a better balance between water supply and demand to sustain the economic growth and socioeconomic development in the context of climatechange.
6. The influence of hydrological model parameter uncer- tainty as represented here is not trivial and leads to un- certainty of up to about 10% in peak season magnitude. Nevertheless, uncertainty associated with climate mod- els dominates the grand ensemble envelope. It is there- fore very clear that the uncertainty in future runoff vari- ations, based on the consideration of several GCM pre- dictions, is far greater than the uncertainty in the cali- bration and application of the hydrological model. Table 2 illustrates the effects of changing the approach for estimating time series variations in potential evaporation from the simple method discussed above to the use of the Hargreaves estimation equation. The values are based on the mean hydrological parameter ensemble for Mukwe in all cases. The Hargreaves method always generates greater runoff (through lower evaporative demand values) and for all of the GCMs, except NCAR, the difference in the cli- mate change signal (relative to the baseline period) is less than 5%. The differences in mean monthly flow between the upper and lower extremes of the simulation ensemble is approximately 7%, suggesting that the uncertainty in the evaluation of appropriate model parameter values is gener- ally greater than the uncertainty in the estimation of potential evaporation variations. This result is almost certainly associ- ated with the fact that actual evaporation losses are affected by moisture availability as much as by atmospheric evapora- tive demand. Mean annual potential evaporation varies from 1900 to 2500 mm whereas rainfall varies from approximately 1200mm to less than 650 mm even under the higher rainfall NCAR scenario.
The project ADAPTACLIMA- EPAL aims to provide socioeconomic scenarios for population growth, land use and water use for an area which includes the Portuguese basin of the Tagus River (Figure 1) with all the municipalities that are supplied directly or indirectly by EPAL, and the west aquifers of continental territory of Portugal. In total, 106 municipalities were included in the study area, of which, 34 are supplied by EPAL. Projections of future water withdrawals will contribute to EPAL, as well as to other stakeholders and policy makers. Other tasks of the project will include modelling future climate and water availability. All the generated data will be analysed and used to provide information to put in place a robust adaptation strategy to reduce vulnerability to future changes. In this paper future water stress for EPAL is evaluated by presenting socioeconomic scenarios for population growth, land use and water use for the project area.
1), this article investigates the characteristics of precipitation and temperature. The historical experiment of CMIP5 uses the result of experiment result before the Industrial Revolution (PiHistorical run) as the initial field for integrating, all the observed data were used and varied from time changes as the force field, such as greenhouse gas, ozone, aerosol, volcanic activity, solar constant. The simulation period is from 1850 to 2005 and the simulation result indicates the correspondence relationship between the recurring of historical climate and actual calendar. Therefore, it can be compared with the observational data to estimate the simulation capability of the climate system model.
Abstract Climatechange and drought phenomena impacts have become a growing concern for waterresources engineers and policy makers, mainly in arid and semi-arid areas. This study aims to contribute to the development of a decision support tool to prepare waterresources managers and planners for climatechangeadaptation. The Hydrologiska Byråns Vattenbalansavdelning (The Water Balance Department of the Hydrological Bureau) hydro- logic model was used to define the boundary conditions for the reservoir capacity yield model comprising daily reservoir inflow from a representative example watershed with the size of 14,924 km 2 into a reservoir with the capacity of 6.80 Gm 3 . The reservoir capacity yield model was used to simulate variability in climatechange-induced differences in reservoir capacity needs and performance (operational probability of failure, resilience, and vulnerability). Owing to the future precipitation reduction and potential evapotranspiration increase during the worst case scenario ( − 40% precipitation and +30% potential evapotranspiration), substantial reduc- tions in streamflow of between − 56% and − 58% are anticipated for the dry and wet seasons, respectively. Furthermore, model simulations recommend that as a result of future climatic conditions, the reservoir operational probability of failure would generally increase due to declined reservoir inflow. The study developed preparedness plans to combat the conse- quences of climatechange and drought.
Received: 26 March 2019; Accepted: 18 April 2019; Published: 24 April 2019 Abstract: This article illustrates the impact of potential future climate scenarios on water quantity in time and space for an East African floodplain catchment surrounded by mountainous areas. In East Africa, agricultural intensification is shifting from upland cultivation into the wetlands due to year-round water availability and fertile soils. These advantageous agricultural conditions might be hampered through climatechange impacts. Additionally, water-related risks, like droughts and flooding events, are likely to increase. Hence, this study investigates future climate patterns and their impact on waterresources in one production cluster in Tanzania. To account for these changes, a regional climate model ensemble of the Coordinated Regional Downscaling Experiment (CORDEX) Africa project was analyzed to investigate changes in climatic patterns until 2060, according to the RCP4.5 (representative concentration pathways) and RCP8.5 scenarios. The semi-distributed Soil and Water Assessment Tool (SWAT) was utilized to analyze the impacts on waterresources according to all scenarios. Modeling results indicate increasing temperatures, especially in the hot dry season, intensifying the distinctive features of the dry and rainy season. This consequently aggravates hydrological extremes, such as more-pronounced flooding and decreasing low flows. Overall, annual averages of water yield and surface runoff increase up to 61.6% and 67.8%, respectively, within the bias-corrected scenario simulations, compared to the historical simulations. However, changes in precipitation among the analyzed scenarios vary between −8.3% and +22.5% of the annual averages. Hydrological modeling results also show heterogeneous spatial patterns inside the catchment. These spatio-temporal patterns indicate the possibility of an aggravation for severe floods in wet seasons, as well as an increasing drought risk in dry seasons across the scenario simulations. Apart from that, the discharge peak, which is crucial for the flood recession agriculture in the floodplain, is likely to shift from April to May from the 2020s onwards.
Climatechange has been increasingly influenced the river flows in the Murray Darling Basin due to decreased annual precipitation, increased in annual temperature and low runoff in this area. The cycle in which water evaporates from the oceans and the land surface, is carried over the Earth in atmospheric circulation as water vapour, condenses to form clouds, precipitates again as rain or snow, is intercepted by trees and vegetation, provides runoff on the land surface, infiltrates into soils, recharges groundwater, and/or discharges into streams and flows out into the oceans, and ultimately evaporates again from the oceans or land surface. The various systems involved in the hydrological cycle are usually referred to as hydrological systems (IPCC 2012). During this runoff, some water passing through the land and store as soil moisture and groundwater.
This study was aimed to compare the uncertainty of two hydrological models in discharge modeling and their performance and catchment hydrological response to climatechange in Megech river catchment. In this study, large scale regional climate model (REMO) output was downscaled statistically to metrological variables at a daily resolution using SDSM model version 5.11. The two hydrological models, HBV-Light and GR4J, were successfully calibrated (1991-1995) and validated (1998-2000) using current climatic inputs and observed river flows. The overall performances of the two models in reproducing historical records were good at daily and monthly time scale both on calibration and validation (NSE=0.91 for HBV and NSE=0.88 for GR4J). The models results in predicting hydrological response of changed climate (2015-2050) was simulated using statistically downscaled 20 ensembles climate scenario data for both A1B and B1 scenarios. Both model results showed a reduction of the peak discharge in August and September The total annual discharge for future period (2015-2050) showed a decreasing trend for HBV-Light simulation and an increasing trend for GR4J simulation. More studies using different hydrological models on different catchments need to be carried out in order to provide more general conclusions about the reliability of the model output.
lakes are extremely sensitive to the balance of inflows and evaporative losses. Even small changes in climate can produce large changes in lake levels and salinity (Laird et al. 1996). Other effects of increased temperature on lakes could include higher thermal stress for cold-water fish, higher trophic states leading to increased productivity and lower dissolved oxygen, degraded water quality and increased summer anoxia. Decreases in lake levels coupled with decreased flows from runoff and groundwater may exacerbate temperature increases and loss of thermal refugia and dissolved oxygen. Increased net evaporation may increase salinity of lakes. Hostetler and Small (1999) also note that climate variability may amplify or offset changes in the mean state under climate changes and may ultimately be more important that changes in average conditions. Some non-linear or threshold events may also occur, such as a fall in lake level that cuts off outflows or separates a lake into two isolated parts. Work is needed to identify threatened lakes in California and projected impacts of such events on downstream flows and groundwater recharge.
Adaptation capacity challenges the very process of development as it seeks to alter the flows of resources, knowledge, or technology; the changes in organizations, institutions and administrative bodies; the so- cial learning processes; and, any form of human, social or political cap- ital ( Eakin & Lemos, 2006; Pelling & High, 2005; Pelling, High, Dearing, & Smith, 2007 ). The case of Playacar highlights the signifi- cance for climatechangeadaptation of representational strategies. On the one hand, it points to the potential of implementing non-essen- tialist strategies that acknowledge the accelerating environment change occurring in the portrayed tourism destinations. On the other hand, it highlights the importance of paying further attention to the ways in which the relationship between humans and nature are ideal- ized. Idealizations based on a neat separation between the urban lives juxtaposed against the exoticism of pristine beaches will increasingly be rendered unrealistic as global climatechange reminds society of the inextricable co-evolution between humans and the environment.
improvement for coping with droughts (Alauddin & Sharma, 2013). The other purpose of the literature is to explore quantitatively who adapts, how, and why. Barbier et al. (2009) compare different responses of households in Burkina Faso to drought by analysing farm decisions after years with poor and good harvests. They conclude that the households have developed strategies for income diversification as a way of reducing dependence on climate, but vulnerability is still considerable. A similar conclusion is reached by Roncoli et al. (2001) who analyse the responses enacted by families of the Central Plateau in Burkina Faso during the year that followed a severe drought in 1997. In addition, Mertz et al. (2009) estimate the relative importance of climate in various adaptive strategies in Senegal. Households identify wind and occasional excess rainfall as the most destructive climate factors. However, they assign economic, political, and social rather than climate factors as the main reasons for change. With respect to Bangladesh, Alauddin and Sarker (2014) identify several adaptation strategies in response to drought such as the cultivation of drought-tolerant rice and non-rice crops or the use of more irrigation water. Similarly, Habiba, Shaw, and Takeuchi (2012) give evidence that, to cope with drought, Bangladeshi farmers have been adapting various practices mainly through agronomic management, crop intensification and water resource exploitation. In addition, evidence shows that people in Bangladesh are used to adjust to cyclones and flooding events by adopting various coping strategies (Del Ninno, Dorosh, Smith, & Roy, 2001, Paul & Routray, 2011; Younus, Bedford, & Morad, 2005).
Climatechange is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. Climatechange refers to a change in average weather conditions, or in the time variation of weather around longer-term average conditions. Climatechange is real, and the causal link to increased greenhouse gas emissions that is now well established (Coondoo and Dinda 2002). Globally, the ten hottest years on record have occurred since 1991, and in the past century, temperatures have increased by about 0.6 0 C (See, IPCC reports for details). In the same period, global sea level has risen by about 20 cm – it is partly due to melting of mountain ice and partly due to thermal expansion of the oceans. Scientific research finds evidences that in last two centuries anthropogenic activities have increased atmospheric greenhouse gases concentration that is more than pre-industrial levels. Only increasing pressure of greenhouse gas emissions and aerosol concentrations in atmosphere could explain the rising trend in temperature in last 100 years (IPCC reports). Recent climatechange is the result of human actions and specially from the burning of fossil fuels and land use changes. Development activities increase the atmospheric concentrations of greenhouse gases (GHG) – mainly carbon dioxide, methane and nitrous oxide. The GHGs are accumulated in the upper level of atmosphere and acts like the roof of GHG that is tapping solar long-wave radiation which raises temperature. It also provokes other forms of climate disruption and accelerates the process. This depends on a complex interplay of many factors, including rates of population expansion, economic growth and patterns of consumption. The effects are not uniform. The changes differ from one location to another. There are different weather consequences, while some regions have intense rainfall, others have more prolonged dry period and few areas have both.