Keywords: Lake water balance Energy budget method Mediterranean climate Physically based hydrolog... more Keywords: Lake water balance Energy budget method Mediterranean climate Physically based hydrological model Climate changes Deforestation s u m m a r y Lake water levels are sensitive sentinels of changes in the climate and landscape of the broader lake catchment. This means that lakes can be useful for quantifying the effects of these changes on the water yield of a catchment. This study presents a water balance model of a closed catchment-lake system in the semi-arid Mediterranean climate over the last 85 years, with the objective to understand the influence of precipitation change and the conversion from Mediterranean maquis to pasture. Deforestation alters the balance between evapotranspiration and canopy interception, and causes the rapid decay of soil hydrological properties, thus changing the mechanisms of runoff generation. The overall impact of these changes on the water yield has been evaluated for the catchment of the lake. A physically based rain-fall–runoff model, combined with the energy budget method for estimating lake evaporation, were used for the lake water balance model. The calibration was carried out with the continuous measurements taken during the period 2008–2013. The reliability was evaluated with the historical lake levels between 1929 and 2008. Simulation errors were small despite the high sensitivity of the water balance model to precipitation, which in the historical period was that of a non-local station. The simulation results show that the balance was influenced by a combination of climate and land-use changes. The 23% decrease in precipitation observed in the last 50-years has resulted in a 72% decrease in average streamflow. The con-temporaneous deforestation in 18% of the catchment area resulted in a 13% decrease in streamflow. The main mechanism of runoff generation under the maquis cover was saturated subsurface-flow. At hill-slope scale this can eliminate the surface runoff, giving the impression that the water yield is lower than that of deforested hillslopes. However, at the basin scale the effect can also be reversed. The reduction in soil hydraulic conductivity and porosity in deforested and altered soils produces higher soil moisture and perched water-table, which means that there are higher evaporation and percolation losses. As simulated by the hydrological model, these higher losses compensate for the greater throughfall. Thus deforestation gives rise to lower water yield in this semi-arid Mediterranean environment.
This experimental research compares the physical and hydraulic properties of two adjacent soils, ... more This experimental research compares the physical and hydraulic properties of two adjacent soils, one covered with a native forest of Mediterranean maquis, and the other with spontaneous grass. The latter replaced the previous natural forest. The aim is to quantify the significant differences in the soil properties caused by the removal of the natural vegetation. Although the soil texture was similar in the different land uses, the soil under the forest had a higher organic matter content, a lower apparent density and a higher water content at saturation than the grassed soil. The analysis of the water retention characteristics indicated that the retained water content of the forest soil exceeded that of the grassed soil in the range from saturation to-50 cm of water tension. This suggests that changing the land use altered the soil pore structure within this range. The hydraulic conductivity of the forest soil exceeded that of the grassed soil at water tensions of-10,-5 and-3 cm. Conversely the hydraulic conductivity of the grassed soil was similar to that of the forest soil at-1 cm of water tension and at saturation. This result was probably due to the hydraulic activation of the desiccation cracks in the grassed soil. This increased the amount of infiltrated water in saturated and near-saturated soil conditions. This work shows that changes in land use have an unfavorable impact on the physical and hydraulic properties of the soil. Soil covered with grass is more vulnerability to water erosion than that under forest, and there is likely to be general worsening of flow regimes.
The new high-resolution images from the satellites as IKONOS, SPOT5, Quickbird2 give us the oppor... more The new high-resolution images from the satellites as IKONOS, SPOT5, Quickbird2 give us the opportunity to map ground features, which were not detectable in the past, by using medium resolution remote sensed data (LANDSAT). More accurate and reliable maps of land cover can then be produced. However, classification procedure with these images is more complex than with the medium resolution remote sensing data for two main reasons: firstly, because of their exiguous number of spectral bands, secondly, owing to high spatial resolution, the assumption of pixel independence does not generally hold. It is then necessary to use new spectral classifiers taking into account also proximal information. In this view, it is necessary to combine both "spectral" and "spatial" features to optimise land use classification. Standard supervised classification techniques, so-called "per-pixel" classifiers, use only spectral information of remote sensing image, whereas negl...
Many agronomic and hydrological investigations depend on accurate measurement of soil water conte... more Many agronomic and hydrological investigations depend on accurate measurement of soil water content (SWC). Accuracy, precision, facility and speed, including the capability to carry out measurements at different depths, are essential characteristics for monitoring SWC in the agronomical experiments. At the present, common systems use sensors based on capacitance (FDR) or time domain reflectometry (TDR) principles. Both the methods introduce advantages and disadvantages. In the framework of AQUATER Project (Decision support systems to manage water resources at irrigation district level in Southern Italy using remote sensing information), the main objective of this study has been to monitor the SWC dynamics in a tomato (Foggia) and watermelon (Castellaneta - TA) field cultivations, both located in Southern Italy, by using: (1) the Diviner 2000 (Sentek Pty. Ltd., South Australia), (2) the TDR-100 (Campbell Sci. Shepshed, UK), (3) ThetaProbe Soil Moisture Sensor-ML2x (Delta-T Devices Lt...
La determinazione dei fattori che influenzano la qualità del suolo e la messa a punto di metodolo... more La determinazione dei fattori che influenzano la qualità del suolo e la messa a punto di metodologie per la sua valutazione rappresentano tematiche di ricerca di notevole rilevanza applicativa che sono oggetto di un crescente interesse da parte della comunità scientifica internazionale. La determinazione della qualità del suolo presuppone analisi e valutazioni di natura fisica, chimica e biologica. La qualità fisica del mezzo poroso influenza i processi chimici e biologici e, pertanto, rappresenta un aspetto di particolare importanza negli studi sulla qualità del suolo (Dexter, 2004a). La qualità fisica di un suolo agricolo viene valutata principalmente con riferimento alle caratteristiche meccaniche ed idrauliche dello strato esplorato dalle radici (Topp et al., 1997; Reynolds et al., 2002). Un suolo agricolo di buona qualità fisica è stabilmente ben strutturato, consente un ancoraggio soddisfacente delle colture, si oppone
The main objective of this study was to determine the soil physical quality, in a long-term resea... more The main objective of this study was to determine the soil physical quality, in a long-term research with two different systems of weed control in an almond-tree (Prunus amygdalus Batsch) orchard submitted to surface tillage (ST) and no tillage (NT) but chemical control in pre-emergence. ST and NT soils showed a good air capacity, ideally-good plant-available water capacity, optimal macroporosity typical of un-degraded soils, while the relative field capacity was optimal only for NT soil. Moreover, we detected an optimal or sub-optimal dry bulk density. According to the S index, this clay soil showed a very good or good quality, which agreed very well with the other indicators evaluated in this study. Finally, the saturated hydraulic conductivity was optimal both in summer and winter seasons.
Spatial variability of soil water content represents an actual and significant challenge, because... more Spatial variability of soil water content represents an actual and significant challenge, because of the difficulties in defining a representative measurement of large field that could be shared between homogeneous zones of management, in size comparable to the correlation distance of soil water variability. The objective of this study was to characterise the spatio-temporal variability of soil water content during the growing season of winter lettuce and evaluate the potential for precision water management. In this study the maps of the stability water distributions were found to be useful tools for precision irrigation water management with temporally stable irrigation water application pattern that can be prescribed even in a spatially variable field according to the partition in management zones for increasing the water use efficiency.
Keywords: Lake water balance Energy budget method Mediterranean climate Physically based hydrolog... more Keywords: Lake water balance Energy budget method Mediterranean climate Physically based hydrological model Climate changes Deforestation s u m m a r y Lake water levels are sensitive sentinels of changes in the climate and landscape of the broader lake catchment. This means that lakes can be useful for quantifying the effects of these changes on the water yield of a catchment. This study presents a water balance model of a closed catchment-lake system in the semi-arid Mediterranean climate over the last 85 years, with the objective to understand the influence of precipitation change and the conversion from Mediterranean maquis to pasture. Deforestation alters the balance between evapotranspiration and canopy interception, and causes the rapid decay of soil hydrological properties, thus changing the mechanisms of runoff generation. The overall impact of these changes on the water yield has been evaluated for the catchment of the lake. A physically based rain-fall–runoff model, combined with the energy budget method for estimating lake evaporation, were used for the lake water balance model. The calibration was carried out with the continuous measurements taken during the period 2008–2013. The reliability was evaluated with the historical lake levels between 1929 and 2008. Simulation errors were small despite the high sensitivity of the water balance model to precipitation, which in the historical period was that of a non-local station. The simulation results show that the balance was influenced by a combination of climate and land-use changes. The 23% decrease in precipitation observed in the last 50-years has resulted in a 72% decrease in average streamflow. The con-temporaneous deforestation in 18% of the catchment area resulted in a 13% decrease in streamflow. The main mechanism of runoff generation under the maquis cover was saturated subsurface-flow. At hill-slope scale this can eliminate the surface runoff, giving the impression that the water yield is lower than that of deforested hillslopes. However, at the basin scale the effect can also be reversed. The reduction in soil hydraulic conductivity and porosity in deforested and altered soils produces higher soil moisture and perched water-table, which means that there are higher evaporation and percolation losses. As simulated by the hydrological model, these higher losses compensate for the greater throughfall. Thus deforestation gives rise to lower water yield in this semi-arid Mediterranean environment.
This experimental research compares the physical and hydraulic properties of two adjacent soils, ... more This experimental research compares the physical and hydraulic properties of two adjacent soils, one covered with a native forest of Mediterranean maquis, and the other with spontaneous grass. The latter replaced the previous natural forest. The aim is to quantify the significant differences in the soil properties caused by the removal of the natural vegetation. Although the soil texture was similar in the different land uses, the soil under the forest had a higher organic matter content, a lower apparent density and a higher water content at saturation than the grassed soil. The analysis of the water retention characteristics indicated that the retained water content of the forest soil exceeded that of the grassed soil in the range from saturation to-50 cm of water tension. This suggests that changing the land use altered the soil pore structure within this range. The hydraulic conductivity of the forest soil exceeded that of the grassed soil at water tensions of-10,-5 and-3 cm. Conversely the hydraulic conductivity of the grassed soil was similar to that of the forest soil at-1 cm of water tension and at saturation. This result was probably due to the hydraulic activation of the desiccation cracks in the grassed soil. This increased the amount of infiltrated water in saturated and near-saturated soil conditions. This work shows that changes in land use have an unfavorable impact on the physical and hydraulic properties of the soil. Soil covered with grass is more vulnerability to water erosion than that under forest, and there is likely to be general worsening of flow regimes.
The new high-resolution images from the satellites as IKONOS, SPOT5, Quickbird2 give us the oppor... more The new high-resolution images from the satellites as IKONOS, SPOT5, Quickbird2 give us the opportunity to map ground features, which were not detectable in the past, by using medium resolution remote sensed data (LANDSAT). More accurate and reliable maps of land cover can then be produced. However, classification procedure with these images is more complex than with the medium resolution remote sensing data for two main reasons: firstly, because of their exiguous number of spectral bands, secondly, owing to high spatial resolution, the assumption of pixel independence does not generally hold. It is then necessary to use new spectral classifiers taking into account also proximal information. In this view, it is necessary to combine both "spectral" and "spatial" features to optimise land use classification. Standard supervised classification techniques, so-called "per-pixel" classifiers, use only spectral information of remote sensing image, whereas negl...
Many agronomic and hydrological investigations depend on accurate measurement of soil water conte... more Many agronomic and hydrological investigations depend on accurate measurement of soil water content (SWC). Accuracy, precision, facility and speed, including the capability to carry out measurements at different depths, are essential characteristics for monitoring SWC in the agronomical experiments. At the present, common systems use sensors based on capacitance (FDR) or time domain reflectometry (TDR) principles. Both the methods introduce advantages and disadvantages. In the framework of AQUATER Project (Decision support systems to manage water resources at irrigation district level in Southern Italy using remote sensing information), the main objective of this study has been to monitor the SWC dynamics in a tomato (Foggia) and watermelon (Castellaneta - TA) field cultivations, both located in Southern Italy, by using: (1) the Diviner 2000 (Sentek Pty. Ltd., South Australia), (2) the TDR-100 (Campbell Sci. Shepshed, UK), (3) ThetaProbe Soil Moisture Sensor-ML2x (Delta-T Devices Lt...
La determinazione dei fattori che influenzano la qualità del suolo e la messa a punto di metodolo... more La determinazione dei fattori che influenzano la qualità del suolo e la messa a punto di metodologie per la sua valutazione rappresentano tematiche di ricerca di notevole rilevanza applicativa che sono oggetto di un crescente interesse da parte della comunità scientifica internazionale. La determinazione della qualità del suolo presuppone analisi e valutazioni di natura fisica, chimica e biologica. La qualità fisica del mezzo poroso influenza i processi chimici e biologici e, pertanto, rappresenta un aspetto di particolare importanza negli studi sulla qualità del suolo (Dexter, 2004a). La qualità fisica di un suolo agricolo viene valutata principalmente con riferimento alle caratteristiche meccaniche ed idrauliche dello strato esplorato dalle radici (Topp et al., 1997; Reynolds et al., 2002). Un suolo agricolo di buona qualità fisica è stabilmente ben strutturato, consente un ancoraggio soddisfacente delle colture, si oppone
The main objective of this study was to determine the soil physical quality, in a long-term resea... more The main objective of this study was to determine the soil physical quality, in a long-term research with two different systems of weed control in an almond-tree (Prunus amygdalus Batsch) orchard submitted to surface tillage (ST) and no tillage (NT) but chemical control in pre-emergence. ST and NT soils showed a good air capacity, ideally-good plant-available water capacity, optimal macroporosity typical of un-degraded soils, while the relative field capacity was optimal only for NT soil. Moreover, we detected an optimal or sub-optimal dry bulk density. According to the S index, this clay soil showed a very good or good quality, which agreed very well with the other indicators evaluated in this study. Finally, the saturated hydraulic conductivity was optimal both in summer and winter seasons.
Spatial variability of soil water content represents an actual and significant challenge, because... more Spatial variability of soil water content represents an actual and significant challenge, because of the difficulties in defining a representative measurement of large field that could be shared between homogeneous zones of management, in size comparable to the correlation distance of soil water variability. The objective of this study was to characterise the spatio-temporal variability of soil water content during the growing season of winter lettuce and evaluate the potential for precision water management. In this study the maps of the stability water distributions were found to be useful tools for precision irrigation water management with temporally stable irrigation water application pattern that can be prescribed even in a spatially variable field according to the partition in management zones for increasing the water use efficiency.
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