scholarly journals Deliberation of Hilly Areas for Water Harvesting Application in Western Crete, Greece.

2016 ◽  
Vol 18 (3) ◽  
pp. 621-629 ◽  
Keyword(s):  
Overland Flow ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Water Harvesting ◽  
Hydrological Conditions ◽  
Monthly Average ◽  
Dry Seasons ◽  
Harvesting Techniques ◽  
The Mean ◽  
Water Problems

<div> <p>The meteorological, physical and hydrological conditions prevailing in a hilly area, namely the region around Malaxa (Western Crete), are analyzed and investigated in relation to water harvesting applications. The literature relating to water harvesting techniques and applications is reviewed and the conclusions that have been drawn by other investigators concerning methods of water harvesting techniques and applications are outlined and discussed. Specific reasons for choosing this particular study area was given and the types and installation of equipment used are also described. The results indicate that despite the fact that the mean annual rainfall can be considered as high (940 mm), its distribution is very uneven and only 6% of it falls from May to September. This fact creates serious water problems in the area during the dry seasons. Also, mean annual and monthly average temperatures have values which contribute to the evapotranspiration of high amount of precipitation and may form frost and overland flow respectively, during some days. Furthermore, the annual runoff is estimated to be 248 mm and a part of this can be overland flow while the other part can be a throughflow. The occurrence of overland flow is also proved by the comparison of the infiltration and the intensities of rainfall with the return periods of 5 and 10 years. Additionally, the quantification of overland flow is made by collecting and analyzing it from experimental plots. By this method, we clarified that the quantity of overland flow is affected by the inclination of the ground, the density of vegetation and the compaction of the soil. These results, although all of them are not wholly conclusive, can present an advance for understanding the use of meteorological, physical and hydrological conditions for water harvesting applications in an area.</p> </div> <p>&nbsp;</p>

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

scholarly journals Effects of surface wind speed decline on modeled hydrological conditions in China

2014 ◽  
Vol 18 (8) ◽  
pp. 2803-2813 ◽  
Author(s):  
X. Liu ◽  
X.-J. Zhang ◽  
Q. Tang ◽  
X.-Z. Zhang
Keyword(s):  
Soil Moisture ◽  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
River Basins ◽  
Annual Runoff ◽  
Infiltration Capacity ◽  
Hydrological Conditions ◽  
Speed Change ◽  
The Mean

Abstract. Surface wind speed decline in China has been widely reported, but its effects on hydrology have not been fully evaluated to date. In this study, the effects of wind speed change on modeled hydrological conditions are investigated using the Variable Infiltration Capacity (VIC) hydrological model for China during the 1966–2011 period. Two model experiments, i.e., VIC simulations with the observed (EXP1) and detrended wind speed (EXP2), are performed over the major river basins in China. The differences between the two experiments are analyzed to assess the effects of wind speed decline. Results show that wind speed has decreased by 29% in China. The wind speed decline would have resulted in a decrease in evapotranspiration of 1–3% of mean annual evapotranspiration and an increase in runoff of 1–6% of mean annual runoff at most basins in China. The sensitivities of evapotranspiration and runoff changes to wind speed change are larger in humid areas than dry areas, while the sensitivity of soil moisture change to wind speed change is situation dependent. The wind speed decline would have offset the expansion of the drought area in China. It has contributed to reducing drought areas by 8.8% of the mean drought area (i.e., approximate 106 × 103 km2 out of 1.2 × 106 km2) over China. The reductions of soil moisture drought induced by wind speed decline are large (more than 5% of the mean drought area) in most basins, except in the Southwest and Pearl River basins.

scholarly journals Long term precipitation chemistry and wet deposition in a remote dry savanna site in Africa (Niger)

2009 ◽  
Vol 9 (5) ◽  
pp. 1579-1595 ◽  
Author(s):  
C. Galy-Lacaux ◽  
D. Laouali ◽  
L. Descroix ◽  
N. Gobron ◽  
C. Liousse
Keyword(s):  
Wet Deposition ◽  
Ph Value ◽  
Precipitation Chemistry ◽  
Annual Rainfall ◽  
Deposition Flux ◽  
Air Concentration ◽  
Ionic Charge ◽  
Rainfall Gradient ◽  
The Mean

Abstract. Long-term precipitation chemistry have been recorded in the rural area of Banizoumbou (Niger), representative of a semi-arid savanna ecosystem. A total of 305 rainfall samples ~90% of the total annual rainfall) were collected from June 1994 to September 2005. From ionic chromatography, pH major inorganic and organic ions were detected. Rainwater chemistry is controlled by soil/dust emissions associated with terrigeneous elements represented by SO42−, Ca2+, Carbonates, K+ and Mg2+. It is found that calcium and carbonates represent ~40% of the total ionic charge. The second highest contribution is nitrogenous, with annual Volume Weighed Mean (VWM) for NO3− and NH4+ concentrations of 11.6 and 18.1 μeq.l−1, respectively. This is the signature of ammonia sources from animals and NOx emissions from savannas soil-particles rain-induced. The mean annual NH3 and NO2 air concentration are of 6 ppbv and 2.6 ppbv, respectively. The annual VWM precipitation concentration of sodium and chloride are both of 8.7 μeq.l−1 which reflects the marine signature of monsoonal and humid air masses. The median pH value is of 6.05. Acidity is neutralized by mineral dust, mainly carbonates, and/or dissolved gases such NH3. High level of organic acidity with 8μeq.l−1 and 5.2 μeq.l−1 of formate and acetate were also found. The analysis of monthly Black Carbon emissions and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) values show that both biogenic emission from vegetation and biomass burning could explain the rainfall organic acidity content. The interannual variability of the VWM concentrations around the mean (1994–2005) is between ±5% and ±30% and mainly due to variations of sources strength and rainfall spatio-temporal distribution. From 1994 to 2005, the total mean wet deposition flux in the Sahelian region is of 60.1 mmol.m−2.yr−1 ±25%. Finally, Banizoumbou measurements are compared to other long-term measurements of precipitation chemistry in the wet savanna of Lamto (Côte d'Ivoire) and in the forested zone of Zoétélé (Cameroon). The total chemical loading presents a maximum in the dry savanna and a minimum in the forest (from 143.7, 100.2 to 86.6 μeq.l−1), associated with the gradient of terrigeneous sources. The wet deposition fluxes present an opposite trend, with 60.0 mmol.m−2.yr−1 in Banizoumbou, 108.6 mmol.m−2.yr−1 in Lamto and 162.9 mmol.m−2.yr−1 in Zoétélé, controlled by rainfall gradient along the ecosystems transect.

How landscape and climate affect the spatial variability of the Italian rainfall extremes? Some initial clues based on I2-RED

2021 ◽  
Author(s):  
Paola Mazzoglio ◽  
Ilaria Butera ◽  
Pierluigi Claps
Keyword(s):  
Spatial Variability ◽  
Linear Regression Analysis ◽  
Alpine Region ◽  
Annual Rainfall ◽  
Mean Values ◽  
Rainfall Extremes ◽  
Geomorphological Parameters ◽  
The Mean ◽  
The Relationship ◽  
Italian Territory

&lt;p&gt;The intensity and the spatial distribution of precipitation depths are known to be highly dependent on relief and geomorphological parameters. Complex environments like mountainous regions are prone to intense and frequent precipitation events, especially if located near the coastline. Although the link between the mean annual rainfall and geomorphological parameters has received substantial attention, few literature studies investigate the relationship between the sub-daily maximum annual rainfall depth and geographical or morphological landscape features.&lt;br&gt;In this study, the mean of the rainfall extremes in Italy, recently revised in the so-called I&lt;sup&gt;2&lt;/sup&gt;-RED dataset, are investigated in their spatial variability in comparison with some landscape and also some broad climatic characteristics. The database includes all sub-daily rainfall extremes recorded in Italy from 1916 until 2019 and this analysis considers their mean values (from 1 to 24 hours) in stations with at least 10 years of records, involving more than 3700 stations.&lt;br&gt;The geo-morpho-climatic factors considered range from latitude, longitude and minimum distance from the coastline on the geographic side, to elevation, slope, openness and obstruction morphological indices, and also include an often-neglected robust climatological information, as the local mean annual rainfall.&lt;br&gt;Obtained results highlight that the relationship between the annual maximum rainfall depths and the hydro-geomorphological parameters is not univocal over the entire Italian territory and over different time intervals. Considering the whole of Italy, the highest correlation is reached between the mean values of the 24-hours records and the mean annual precipitation (correlation coefficient greater than 0.75). This predominance remains also in sub-areas of the Italian territory (i.e., the Alpine region, the Apennines or the coastal areas) but correlation decreases as the time interval decreases, except for the Alpine region (0.73 for the 1-hour maximum). The other geomorphological parameters seem to act in conjunction, making it difficult to evaluate, with a simple linear regression analysis, their impact. As an example, the absolute value of the correlation coefficient between the elevation and the 1-hour extremes is greater than 0.35 for the Italian and the Alpine regions, while for the 24-hours interval it is greater than 0.35 over the coastal areas.&lt;br&gt;To further investigate the spatial variability of the relationship between rainfall and elevation, a spatial linear regression analysis has been undertaken. Local linear relationships have been fitted in circles centered on any of the 0.5-km size pixels in Italy, with 1 to 30 km radius and at least 5 stations included. Results indicate the need of more comprehensive terrain analysis to better understand the causes of local increasing or decreasing relations, poorly described in the available literature.&lt;/p&gt;

Climate and land use change impacts on water resources in Sardinia (Italy)

2021 ◽  
Author(s):  
Dario Ruggiu ◽  
Salvatore Urru ◽  
Roberto Deidda ◽  
Francesco Viola
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Land Use Change ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Regional Scale ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Land Use Scenarios ◽  
Near Future

&lt;p&gt;The assessment of climate change and land use modifications effects on hydrological cycle is challenging. We propose an approach based on Budyko theory to investigate the relative importance of natural and anthropogenic drivers on water resources availability. As an example of application, the proposed approach is implemented in the island of Sardinia (Italy), which is affected by important processes of both climate and land use modifications. In details, the proposed methodology assumes the Fu&amp;#8217;s equation to describe the mechanisms of water partitioning at regional scale and uses the probability distributions of annual runoff (Q) in a closed form. The latter is parametrized by considering simple long-term climatic info (namely first orders statistics of annual rainfall and potential evapotranspiration) and land use properties of basins.&lt;/p&gt;&lt;p&gt;In order to investigate the possible near future water availability of Sardinia, several climate and land use scenarios have been considered, referring to 2006-2050 and 2051-2100 periods. Climate scenarios have been generated considering fourteen bias corrected outputs of climatic models from EUROCORDEX&amp;#8217;s project (RCP 8.5), while three land use scenarios have been created following the last century tendencies.&lt;/p&gt;&lt;p&gt;Results show that the distribution of annual runoff in Sardinia could be significantly affected by both climate and land use change. The near future distribution of Q generally displayed a decrease in mean and variance compared to the baseline. &amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;The reduction of&amp;#160; Q is more critical moving from 2006-2050 to 2051-2100 period, according with climatic trends, namely due to the reduction of annual rainfall and the increase of potential evapotranspiration. The effect of LU change on Q distribution is weaker than the climatic one, but not negligible.&lt;/p&gt;

scholarly journals Erosive rainfall in the Rio do Peixe Valley: Part III - Risk of extreme events

2018 ◽  
Vol 22 (1) ◽  
pp. 63-68
Author(s):  
Álvaro J. Back ◽  
Augusto C. Pola ◽  
Nilzo I. Ladwig ◽  
Hugo Schwalm
Keyword(s):  
Extreme Events ◽  
Annual Rainfall ◽  
Data Series ◽  
Rainfall Erosivity ◽  
Significance Level ◽  
Control Structures ◽  
Kolmogorov Smirnov ◽  
Runoff Control ◽  
The Mean ◽  
Erosive Rainfall

ABSTRACT Understanding the risks of extreme events related to soil erosion is important for adequate dimensioning of erosion and runoff control structures. The objective of this study was to determine the rainfall erosivity with different return periods for the Valley of the Rio do Peixe in Santa Catarina state, Brazil. Daily pluviographic data series from 1984 to 2014 from the Campos Novos, and Videira meteorological stations and from 1986 to 2014 from the Caçador station were used. The data series of maximum annual rainfall intensity in 30 min, maximum annual erosive rainfall, and total annual erosivity were analyzed for each station. The Gumbel-Chow distributions were adjusted and their adhesions were evaluated by the Kolmogorov-Smirnov test at a significance level of 5%. The Gumbel-Chow distribution was adequate for the estimation of all studied variables. The mean annual erosivity corresponds to the return period of 2.25 years. The data series of the annual maximum individual rainfall erosivity coefficients varied from 47 to 50%.

scholarly journals Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

2015 ◽  
Vol 19 (6) ◽  
pp. 2805-2819 ◽  
Author(s):  
I. Jalón-Rojas ◽  
S. Schmidt ◽  
A. Sottolichio
Keyword(s):  
River Flow ◽  
Hysteresis Loops ◽  
Annual Runoff ◽  
Transitional Period ◽  
Estuarine System ◽  
Upstream Migration ◽  
Hydrological Conditions ◽  
Frequency Monitoring ◽  
Turbidity Level ◽  
River Floods

Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

scholarly journals Features of the Spring Flood Formation in the Arpa River Basin

2021 ◽  
pp. 126-152
Author(s):  
Keyword(s):  
River Basin ◽  
Weighted Average ◽  
Close Correlation ◽  
Annual Runoff ◽  
Average Height ◽  
Spring Flood ◽  
Correlation Relationship ◽  
Catchment Areas ◽  
The Mean ◽  
Maximum Runoff

The article considers main physical and geographical factors affecting the runoff, spring flood of rivers in the Arpa River basin, and analyzes the regularities of their spacetime distribution. The authors have obtained correlation relationship between the values of the flood runoff layer, the mean module maximum runoff and weighted average height of the catchment area of the Arpa River, between the mean annual maximum runoff module for the period floods and catchment areas of rivers. These dependencies can be used for preliminary estimates of the spring flood runoff of unexplored rivers of the territory under consideration. A close correlation between the values of the annual runoff and the runoff of the spring flood in the section of the Arpa River – Dzhermuk has been also revealed. It can be used for forecasting the annual flow.

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