The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, th...The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, the creation of precise DEMs （Digital Elevation Models） of rivers represents an affordable tool to analyze geomorphic variations and budgets, except for wetted areas, where reliable channel digitalization can normally be obtained only using expensive bathymetric surveys. The proposed work aims at improving channel surface models without having available bathymetric sensors, by deriving dry areas elevations from LiDAR data and water depth of wetted areas from aerial photos through a predictive depth-colour relationship. The methodology was applied to two different sub-reaches of the Piave River, a gravel-bed river which suffered severe flood events in 2010. Erosion and deposition patterns were identified through DEM differencing, showing a predominance of scour processes which can lead to channel instability situations. The bathymetric output was compared to other previously-derived models confirming the accuracy of the in-channel elevation estimates. Finally, a discussion on the role played by longitudinal protections during the studied flood events is proposed, focusing the attention on the incidence of two major bank erosions that removed significant volumes of stable areas.展开更多
To face climatic changes, the increase of frequency and severity of droughts, and economic development pressures, Water Management Institutions point at the necessity of water conserving. A sustainable demand-led appr...To face climatic changes, the increase of frequency and severity of droughts, and economic development pressures, Water Management Institutions point at the necessity of water conserving. A sustainable demand-led approach is the most viable option, focusing on achieving more efficient irrigation practices instead of less sustainable expansion of supply. The aim of this work is to investigate on some aspects of the rational water management for the irrigation of corn in order to evaluate the actual possibility of introduction of drip irrigation systems on the Venetian Plain. Trials were carried out on a farm located in Isola della Scala (Verona, Italy) in an area of about 13 ha (12 ha with a drip irrigation system and 1 ha with a solid-set sprinkler system);the effects of the performance of the two systems on waxy corn yield were considered. In particular, water distribution uniformity, water use efficiency, and yield performance of irrigation systems were evaluated. DUlq and CU coefficients for distribution uniformity and IWUe and WUEb indexes for water use efficiency were calculated. To visualize and better analyze the distribution uniformity, the crop yield and the efficiency parameters, ArcGIS 10 (ESRI?) with IDW interpolation were used to create maps. First results show a good water uniformity distribution in the drip irrigation system but only with a careful and proper design of the entire system. As regards the water use efficiency, drip irrigation values are lower than those of sprinkler irrigation (-46% for IWUe and -25% for WUEb), probably due to different irrigation management and water volumes used: in fact, drip irrigation was scheduled every three days, while only supplemental operations were done for sprinkler irrigation. No statistical correlation was found between application rate and yield for both irrigations systems, while a significant correlation was found between irrigation volume and crop water use efficiency. The profitability of the two irrigation systems was compared. The results show that the income of drip irrigation is slightly lower than sprinkler irrigation, mostly due to the use of “throw away” drip lines.展开更多
文摘The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, the creation of precise DEMs （Digital Elevation Models） of rivers represents an affordable tool to analyze geomorphic variations and budgets, except for wetted areas, where reliable channel digitalization can normally be obtained only using expensive bathymetric surveys. The proposed work aims at improving channel surface models without having available bathymetric sensors, by deriving dry areas elevations from LiDAR data and water depth of wetted areas from aerial photos through a predictive depth-colour relationship. The methodology was applied to two different sub-reaches of the Piave River, a gravel-bed river which suffered severe flood events in 2010. Erosion and deposition patterns were identified through DEM differencing, showing a predominance of scour processes which can lead to channel instability situations. The bathymetric output was compared to other previously-derived models confirming the accuracy of the in-channel elevation estimates. Finally, a discussion on the role played by longitudinal protections during the studied flood events is proposed, focusing the attention on the incidence of two major bank erosions that removed significant volumes of stable areas.
文摘To face climatic changes, the increase of frequency and severity of droughts, and economic development pressures, Water Management Institutions point at the necessity of water conserving. A sustainable demand-led approach is the most viable option, focusing on achieving more efficient irrigation practices instead of less sustainable expansion of supply. The aim of this work is to investigate on some aspects of the rational water management for the irrigation of corn in order to evaluate the actual possibility of introduction of drip irrigation systems on the Venetian Plain. Trials were carried out on a farm located in Isola della Scala (Verona, Italy) in an area of about 13 ha (12 ha with a drip irrigation system and 1 ha with a solid-set sprinkler system);the effects of the performance of the two systems on waxy corn yield were considered. In particular, water distribution uniformity, water use efficiency, and yield performance of irrigation systems were evaluated. DUlq and CU coefficients for distribution uniformity and IWUe and WUEb indexes for water use efficiency were calculated. To visualize and better analyze the distribution uniformity, the crop yield and the efficiency parameters, ArcGIS 10 (ESRI?) with IDW interpolation were used to create maps. First results show a good water uniformity distribution in the drip irrigation system but only with a careful and proper design of the entire system. As regards the water use efficiency, drip irrigation values are lower than those of sprinkler irrigation (-46% for IWUe and -25% for WUEb), probably due to different irrigation management and water volumes used: in fact, drip irrigation was scheduled every three days, while only supplemental operations were done for sprinkler irrigation. No statistical correlation was found between application rate and yield for both irrigations systems, while a significant correlation was found between irrigation volume and crop water use efficiency. The profitability of the two irrigation systems was compared. The results show that the income of drip irrigation is slightly lower than sprinkler irrigation, mostly due to the use of “throw away” drip lines.
