Suchergebnisse

Water is one of the essential elements for the nature and human being. The development of good practise of managing water resources are necessary to maintain sufficient availability and to support socio-economic activities and preserve natural ecosystems. For these reasons, it is fundamental to improve the knowledge of cause-effect relations that drives hydrological cycle, which determines water availability. Climate and land use (LU) are two of the main drivers of the water cycle and indeed, the knowledge of their influence on hydrology is a fundamental research question. Of course, the future water availability is strictly related to future climatic and LU scenarios and then a critical role is assumed by the prediction and assessment of these two. A climate and LU change impact study will be developed to investigate the near-future water availability in the Mediterranean area. In detail, on the basis of the state of art and the actual knowledge, the main objective of this dissertation is to estimate the probability density function (pdf) of annual surface runoff Q in transient climate and LU conditions in the island of Sardinia (Italy). The study case has been selected due to the ongoing important process of climate change, overexploitation and degradation of natural resources affecting the entire island (see e.g. ISPRA, ENEA and CIRCE studies). These analyses might have a strategic importance for stakeholders and government agencies that are interested in the management of water resources due to the well-known issue of water availability in the Mediterranean area. The knowledge of the near-future impact of climate and LU change could be useful to establish regional guidelines and good practices to avoid the ongoing reduction of water resources in Sardinia. After a detailed review of the existing methodologies for describing and detecting climate and LU change and their influence in hydrological processes, a methodology based on the Budyko's theory that aims at assessing near future Q pdf in a closed form has been adopted. Five parameters are requested, referring to mean and standard deviation of annual rainfall P and annual potential evapotranspiration PET and Fu's parameter ω. Sets of these parameters will be assessed to define different climatic and LU scenarios for the near future. EUROCORDEX and Land Use CORINE projects will be used to represent climate and LU in the present and in the near future. Results showed that in the near future Q will decrease due to the reduction of P and the increase of PET. The variability of Q will decrease due the reduction of variability of P. Finally, it has been observed that in Sardinia the main driver in the change of Q pdf will be climate change, while the LU plays a secondary role.

Water development projects have altered the environmental flow landscapes where dams and diversions have been built, and this could have effects on coastal resources, particularly in estuaries. Water is an important human resource and water needs grow as populations grow. However, freshwater inflow to the coast is fundamental to the functioning of estuaries. Can we have stable, secure, and sufficient water resources for people and still protect estuarine health? Estuaries are the most productive environments on Earth, and this is in part due to freshwater inflow, which dilutes marine water, and transports nutrients and sediments to the coast. Estuaries are characterized by salinity and nutrient gradients, which are important in regulating many biological processes. As water is diverted for human consumption, it is common for many environmental problems to appear. While many countries have water quality programs, few are dealing with water quantity alterations. The first step is to define marine resources to protect, and the water quality conditions those resources need to thrive. The second step is to determine the flow regimes needed to maintain the desired water quality conditions. Finally, many regions are using adaptive management programs to manage freshwater resources. These programs set goals to protect ecosystem resources, identify indicators, and monitor the indicators over time to ensure that the goals are appropriate and resources are protected. Case studies demonstrate that monitoring and research can determine the ecological and socio-economical impacts of altered freshwater inflows, and stakeholders and managers can make well-informed decisions to manage freshwater inflows to local coasts wisely. ​

The Murray-Darling Basin is Australia's food bowl and home to many iconic water bodies that are culturally and ecologically highly valued. The recent Millennium Drought (from mid-1990s to 2009) was the most severe hydrological drought since records started in the late 19th century. It severely impacted on the basin and for many acted as a wake-up call. To address the ongoing declines in water resources and environmental conditions and to prepare the region for climate change, Australia's Governments are currently attempting to introduce a new comprehensive, and integrated approach to the management of the basin's water resources. In this paper, long-term time series of climate, hydrological and environmental data are used to analyze how compounding stresses have gradually affected the hydrological system and its services. Major hydroclimatic stresses considered in this paper include salinity, water use, droughts, and climate change. Other, more localized or minor stresses exist (groundwater extraction, farm dams, afforestation, bush fires, cyanobacterial blooms and pollutants) and are reviewed more briefly. The history of water policy and planning shows that Government actions have been strongly influential on the basin. A shift in the strategic goals from water development to the protection and restoration of environmental assets is noticeable since the mid 1990s. Median climate change projections by 2030 indicate smaller reductions in rainfall and runoff than those observed during the recent Millennium Drought, but have a relatively high uncertainty attached to them. The use of regional approaches to reduce that uncertainty, such as statistical downscaling, points to a sizeable decline in rainfall by the end of the century. Most climate projections used for planning consider greenhouse emission scenarios that have smaller global emission trends than the one observed over the last decade. Other, 'less optimistic' scenarios have to be considered for long-term water planning and food security. Compounding all these stresses, is the naturally high hydroclimatic variability of this semi-arid region, that may have been insufficiently considered during previous water development and planning efforts. Successful water planning will need to balance cultural and ecological values with food production, account for high natural variability and uncertainty in climate change projections, learn from past mistakes and be cognizant of future hydrological changes.

The wettest 2018 long rainy season (March to May (MAM)) resulted in daily intensive rainfall events in East Africa that have seriously affected the environment and economy in many countries. Land subsidence is one of the environmental disasters that has occurred due to the long rainy season in Kenya for many years. However, it has received limited scientific attention. In this paper, we incorporate hydrological (soil moisture active&ndash ; passive (SMAP) and loading models) and geodetic data (global positioning system (GPS) and interferometric synthetic aperture radar (InSAR)) to study hydrological changes and their associated subsidence potential in Kenya. Results show that widespread subsidence of more than 20 mm was associated with the MAM season in Kenya during 2018, based on SBAS InSAR measurements. The high values of land subsidence were well correlated with the areas of intense flooding during the MAM season. The widespread subsidence during the wet season has implications for the stability of the earth&rsquo ; s surface during the season rather than creating the possibility of potential stresses along active faults. These stresses may trigger seismicity that is expected to pose risks to urban features. The results of the current study can help governmental authorities to adopt proper urban planning that avoids or minimizes the risks of land subsidence in the areas of sinkholes.

The Murray-Darling Basin is Australia's food bowl and home to many iconic water bodies that are culturally and ecologically highly valued. The recent Millennium Drought (from mid-1990s to 2009) was the most severe hydrological drought since records started in the late 19th century. It severely impacted on the basin and for many acted as a wake-up call. To address the ongoing declines in water resources and environmental conditions and to prepare the region for climate change, Australia's Governments are currently attempting to introduce a new comprehensive, and integrated approach to the management of the basin's water resources. In this paper, long-term time series of climate, hydrological and environmental data are used to analyze how compounding stresses have gradually affected the hydrological system and its services. Major hydroclimatic stresses considered in this paper include salinity, water use, droughts, and climate change. Other, more localized or minor stresses exist (groundwater extraction, farm dams, afforestation, bush fires, cyanobacterial blooms and pollutants) and are reviewed more briefly. The history of water policy and planning shows that Government actions have been strongly influential on the basin. A shift in the strategic goals from water development to the protection and restoration of environmental assets is noticeable since the mid 1990s. Median climate change projections by 2030 indicate smaller reductions in rainfall and runoff than those observed during the recent Millennium Drought, but have a relatively high uncertainty attached to them. The use of regional approaches to reduce that uncertainty, such as statistical downscaling, points to a sizeable decline in rainfall by the end of the century. Most climate projections used for planning consider greenhouse emission scenarios that have smaller global emission trends than the one observed over the last decade. Other, 'less optimistic' scenarios have to be considered for long-term water planning and food security. Compounding all these stresses, is the naturally high hydroclimatic variability of this semi-arid region, that may have been insufficiently considered during previous water development and planning efforts. Successful water planning will need to balance cultural and ecological values with food production, account for high natural variability and uncertainty in climate change projections, learn from past mistakes and be cognizant of future hydrological changes.

Abstract. Assessing hydrological effects of global climate change at local scales is important for evaluating future hazards to society. However, applying climate model projections to local impact models can be difficult as outcomes can vary considerably between different climate models, and including results from many models is demanding. This study combines multiple climate model outputs with hydrological impact modelling through the use of response surfaces. Response surfaces represent the sensitivity of the impact model to incremental changes in climate variables and show probabilies for reaching a priori determined thresholds. Response surfaces were calculated using the HBV hydrological model for three basins in Sweden. An ensemble of future climate projections was then superimposed onto each response surface, producing a probability estimate for exceeding the threshold being evaluated. Site specific impacts thresholds were used where applicable. Probabilistic trends for future change in hazards or potential can be shown and evaluated. It is particularly useful for visualising the range of probable outcomes from climate models and can easily be updated with new results as they are made available.

Climate-related changes in glacierized watersheds are widely documented, stimulating adaptive responses among the 370 million people living in glacier-influenced watersheds as well as aquatic and riparian ecosystems. The situation denotes important interdependencies between science, society, and ecosystems, yet integrative approaches to the study of adaptation to such changes remain scarce in both the mountain- and non-mountain-focused adaptation scholarship. Using the example of glacio-hydrological change, it is argued here that this analytical limitation impedes the identification, development, and implementation of "successful" adaptations. In response, the paper introduces three guiding principles for robust adaptation research in glaciated mountain regions. Principle 1: Adaptation research should integrate detailed analyses of watershed-specific glaciological and hydro-meteorological conditions; glacio-hydrological changes are context-specific and therefore cannot be assumed to follow idealized trajectories of "peak water". Principle 2: Adaptation research should consider the complex interplay between glacio-hydrological changes and socio-economic, cultural, and political conditions; responses to environmental changes are non-deterministic and therefore not deducible from hydrological changes alone. Principle 3: Adaptation research should be attentive to interdependencies, feedbacks, and tradeoffs between human and ecological responses to glacio-hydrological change; research that does not evaluate these socio-ecological dynamics may lead to maladaptive adaptation plans. These principles call attention to the linked scientific, social, and ecological dimensions of adaptation, and offer a point of departure for future climate change adaptation research in high mountains. ; Arts, Faculty of ; Science, Faculty of ; Geography, Department of ; Resources, Environment and Sustainability (IRES), Institute for ; Reviewed ; Faculty

Abstract. The 23 July 1930 earthquake (MS=6.7) in the Southern Apennines (Italy) was a catastrophic event that produced many effects such as surface faulting, fractures, landslides, settlements, hydrological changes, variations in chemical/physical activity related to the volcanic and/or thermal zones and also acoustic and optical phenomena. It is the first great earthquake of the twentieth century that was studied, thanks to the hydrological monitoring network of the Italian Hydrographic Survey (IHS) set up from 1925 to 1929. For this earthquake we analysed the initial IHS hydrometric and pluviometric data, looking for significant anomalies in springs, water wells and mountain streams. Hydrological data relative to rivers, springs and water wells indicate that some changes can be correlated with the earthquake: a post-seismic excess discharge in some streams, pre- and co-seismic decreases in stream flows and water levels in wells, pre- and post-seismic increases in discharges. The pre- and co-seismic stresses and the tectonic deformations were studied in order to find a possible model of interaction between stress state and hydrological variations. The anomalies found in this work can be considered "rebound anomalies", which are the most common precursor reported by many authors and related to increases in porosity and permeability caused by the fracturing that precedes an earthquake. An estimation of the total excess discharge (0.035 km3) caused by the MS=6.7 Irpinia earthquake is consistent with the excess discharge of about 0.01 km3 determined for the Mw=6.9 Loma Prieta earthquake.