Are climate models that allow better approximations of local meteorology better for the assessment of hydrological impacts? A statistical analysis of droughts

This work studies the benefit of using more reliable local climate scenarios to analyse hydrological impacts. It assumes that more reliable local scenarios are defined with the statistically corrected Regional Climate Model (RCM) simulations when they provide better approximations to the historical basic and drought statistics. The paper analyses if the best solutions in terms of their approximation to the local meteorology also provide the best hydrological assessments. A classification of the corrected RCM simulations attending to both approximations is performed. It has been applied in the Cenajo Basin (southeast Spain), where we demonstrate that the best approximations of the historical meteorological statistics provide also the best approximations of the hydrology ones. The selected RCMs were used to generate future (2071–2100) local scenarios under the RCP 8.5 emission scenario. The two selected RCMs predict significant changes of mean precipitation (−31.6 and −44.0 %) and mean temperature (+26.0 and +32.2 %). They also predict higher frequency (from 5 events in the historical period to 20 and 22 in the future), length (4.8 to 7.4 and 10.5 months), magnitude (2.53 to 6.56 and 9.62 SPI) and intensity (0.48 to 1.00 and 0.94 SPI) of extreme meteorological droughts.

Urban Rainwater and Flood Management

In recent decades, a wide range of approaches have been developed to mitigate hydrological impacts as well as the influence on water quality due to urbanization [...]

Are extreme precipitation events becoming stronger and warmer in the Andes?

<p>The Andes Cordillera serves as a physical barrier that modulates the atmospheric fluid dynamics, affecting the occurrence and intensity of precipitation events through orographic enhancement and the blocking and deviation of humidity transported by jets. The quantification of extreme precipitation events (EPEs) and their associated temperature is critical to address hydrological impacts and water availability for the Andes that also feeds the majority of the river and population in the region. </p><p>As the atmosphere is getting warmer, the increasing amount of water vapor available in the troposphere is expected to enhance warm precipitation events during the 21st century. In this study, we examine observational trends in extreme precipitation events by season and analyze possible connections with air temperature. To this end, we perform Sen's Tests and compute Mann-Kendall values Maximum Precipitation daily precipitation and its associated temperature at ~80 meteorological stations. Then, we cluster the results geographically finding positive trends in high elevation areas for extreme precipitation events (EPEs) and their temperature, especially in mid-latitudes. In low stations (<800 m a.s.l.), we obtain a decrease in the magnitude of EPEs but and a decrease in air temperature (up to -0.4 [°C/decade]). In general, the temperature increase in EPEs for high elevation stations < 0.12 °C/year and could rise the freezing level up to 1000 [m], during the fall season.  The presented here suggest positive feedback between warmer atmospheric conditions and the open further pathways regarding hydrological impacts such as debris flow, floods, and less snow availability in the Andes regions.</p>

A novel toolkit to streamline Land Use Land Cover change assessment in the SWAT+ model to enhance flood management and infrastructure decisions

<p>Land Use Land Cover (LULC) change is widely recognised as one of the most important factors impacting river basin hydrology.  It is therefore imperative that the hydrological impacts of various LULC changes are considered for effective flood management strategies and future infrastructure decisions within a catchment.  The Soil and Water assessment Tool (SWAT) has been used extensively to assess the hydrological impacts of LULC change.  Areas with assumed homogeneous hydrologic properties, based on their LULC, soil type and slope, make up the basic computational units of SWAT known as the Hydrologic Response Units (HRUs).  LULC changes in a catchment are typically modelled by SWAT through alterations to the input files that define the properties of these HRUs.  However, to our knowledge at least, the process of making such changes to the SWAT input files is often cumbersome and non-intuitive.  This affects the useability of SWAT as a decision support tool amongst a wider pool of applied users (e.g., engineering teams in environmental regulatory agencies and local authorities).  In this study, we seek to address this issue by developing a user-friendly toolkit that will: (1) allow the end user to specify, through a Graphical User Interface (GUI), various types of LULC changes at multiple locations within their study catchment, (2) run the SWAT+ model (the latest version of SWAT) with the specified LULC changes, and (3) enable interactive visualisation of the different SWAT+ output variables to quantify the hydrological impacts of these scenarios.  Importantly, our toolkit does not require the end user to have any operational knowledge of the SWAT+ model to use it as a decision support tool.  Our toolkit will be trialled at 15 catchments in Gwynedd county, Wales, which has experienced multiple occurrences of high flood events, and consequent economic damage, in the recent past.  We anticipate this toolkit to be a valuable addition to the decision-making processes of Gwynedd County Council for the planning and development of future flood alleviation schemes as well as other infrastructure projects.</p>