On predicting upland erosion losses from rainfall depth

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.

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Initial abstraction ratio and Curve Number estimation using rainfall and runoff data from a tropical watershed

RBRH ◽

10.1590/2318-0331.241920170199 ◽

2019 ◽

Vol 24 ◽

Cited By ~ 2

Author(s):

Luiz Claudio Galvão do Valle Junior ◽

Dulce Buchala Bicca Rodrigues ◽

Paulo Tarso Sanches de Oliveira

Keyword(s):

Conversion Factor ◽

Poor Performance ◽

Curve Number ◽

Storm Events ◽

Rainfall Runoff ◽

Initial Abstraction ◽

Rainfall Depth ◽

Standard Value ◽

Tropical Watershed ◽

Runoff Events

ABSTRACT The Curve Number (CN) method is extensively used for predict surface runoff from storm events. However, remain some uncertainties in the method, such as in the use of an initial abstraction (λ) standard value of 0.2 and on the choice of the most suitable CN values. Here, we compute λ and CN values using rainfall and runoff data to a rural basin located in Midwestern Brazil. We used 30 observed rainfall-runoff events with rainfall depth greater than 25 mm to derive associated CN values using five statistical methods. We noted λ values ranging from 0.005 to 0.455, with a median of 0.045, suggesting the use of λ = 0.05 instead of 0.2. We found a S0.2 to S0.05 conversion factor of 2.865. We also found negative values of Nash-Sutcliffe Efficiency (to the estimated and observed runoff). Therefore, our findings indicated that the CN method was not suitable to estimate runoff in the studied basin. This poor performance suggests that the runoff mechanisms in the studied area are dominated by subsurface stormflow.

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THE USE OF NON-DIMENSIONAL ONE-PARAMETER FUNCTIONS FOR THE DETERMINATION OF REGIONAL RAINFALL DEPTH-DURATION-FREQUENCY RELATIONS

International Association of Scientific Hydrology Bulletin ◽

10.1080/02626667109493049 ◽

1971 ◽

Vol 16 (2) ◽

pp. 67-77

Author(s):

S. DALINSKY

Keyword(s):

Rainfall Depth ◽

Regional Rainfall

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Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the northern highlands of Ethiopia

Hydrology and Earth System Sciences ◽

10.5194/hess-14-2207-2010 ◽

2010 ◽

Vol 14 (11) ◽

pp. 2207-2217 ◽

Cited By ~ 94

Author(s):

T. Y. Tebebu ◽

A. Z. Abiy ◽

A. D. Zegeye ◽

H. E. Dahlke ◽

Z. M. Easton ◽

...

Keyword(s):

Water Table ◽

Gully Erosion ◽

Grazing Land ◽

Cross Sectional ◽

Lake Tana ◽

Erosion Rates ◽

Remotely Sensed Imagery ◽

Reservoir Siltation ◽

Upland Erosion ◽

Elevated Water

Abstract. Gully formation in the Ethiopian Highlands has been identified as a major source of sediment in water bodies, and results in sever land degradation. Loss of soil from gully erosion reduces agricultural productivity and grazing land availability, and is one of the major causes of reservoir siltation in the Nile Basin. This study was conducted in the 523 ha Debre-Mawi watershed south of Bahir Dar, Ethiopia, where gullies are actively forming in the landscape. Historic gully development in a section of the Debre-Mawi watershed was estimated with semi structured farmer interviews, remotely sensed imagery, and measurements of current gully volumes. Gully formation was assessed by instrumenting the gully and surrounding area to measure water table levels and soil physical properties. Gully formation began in the late 1980's following the removal of indigenous vegetation, leading to an increase in surface and subsurface runoff from the hillsides. A comparison of the gully area, estimated from a 0.58 m resolution QuickBird image, with the current gully area mapped with a GPS, indicated that the total eroded area of the gully increased from 0.65 ha in 2005 to 1.0 ha in 2007 and 1.43 ha in 2008. The gully erosion rate, calculated from cross-sectional transect measurements, between 2007 and 2008 was 530 t ha−1 yr−1 in the 17.4 ha area contributing to the gully, equivalent to over 4 cm soil loss over the contributing area. As a comparison, we also measured rill and interrill erosion rates in a nearby section of the watershed, gully erosion rates were approximately 20 times the measured rill and interrill rates. Depths to the water table measured with piezometers showed that in the actively eroding sections of the gully the water table was above the gully bottom and, in stable gully sections the water table was below the gully bottom during the rainy season. The elevated water table appears to facilitate the slumping of gully walls, which causes the gully to widen and to migrate up the hillside.

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An Exponential Rainfall Depth-Intensity Formulation for Western Nigeria

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.18-19.557 ◽

2007 ◽

Vol 18-19 ◽

pp. 557-562

Author(s):

O.A. Ehigiator ◽

B.U. Anyata

Keyword(s):

Rainfall Depth

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Numerical Analysis of the Transport and Fate of Nitrate in the Soil and Nitrate Leaching to Drains

The Scientific World JOURNAL ◽

10.1100/tsw.2001.344 ◽

2001 ◽

Vol 1 ◽

pp. 170-180 ◽

Cited By ~ 4

Author(s):

Alaa El-Sadek ◽

Mona Radwan ◽

Jan Feyen

Keyword(s):

Nitrate Leaching ◽

Initial Conditions ◽

Continuous Cropping ◽

Nitrogen Transport ◽

State Variables ◽

Nitrogen Application ◽

Transport And Transformation ◽

Bottom Boundary Condition ◽

Rainfall Depth ◽

Simulation Results

In this study, the transport and fate of nitrate within the soil profile and nitrate leaching to drains were analyzed by comparing historic field data with the simulation results of the DRAINMOD model. The nitrogen version of DRAINMOD was used to simulate the performance of the nitrogen transport and transformation of the Hooibeekhoeve experiment, situated in the sandy region of the Kempen (Belgium) and conducted for a 30-year (1969–1998) period. In the analysis, a continuous cropping with maize was assumed. Comparisons between experimentally measured and simulated state variables indicate that the nitrate concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions, and the rainfall depth and distribution. Furthermore, the study reveals that the model used gives a fair description of the nitrogen dynamics in the soil and subsurface drainage at field scale. From the comparative analysis between experimental data and simulation results it can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting in an acceptable level of nitrate leaching for the environment.

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Soil and Water Conservation in Rainfed Vineyards with Common Sainfoin and Spontaneous Vegetation under Different Ground Conditions

Water ◽

10.3390/w10081058 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1058 ◽

Cited By ~ 20

Author(s):

Nahed Ben-Salem ◽

Sara Álvarez ◽

Manuel López-Vicente

Keyword(s):

Water Conservation ◽

Cover Crop ◽

Sediment Traps ◽

Sediment Yields ◽

Rainfall Depth ◽

Ephemeral Gullies ◽

Ground Conditions ◽

Spontaneous Vegetation ◽

The Mean ◽

Moisture Conditions

Soil erosion seriously affects vineyards. In this study, the influence of two vegetation covers on topsoil moisture and the effect of different physiographic conditions on runoff and sediment yields were evaluated in a rainfed vineyard formed by four fields (NE Spain) during 15 months. One field had spontaneous vegetation in the inter-row areas, and three fields had a cover crop of common sainfoin. Moisture conditions were dry and stable in the vineyards’ rows, wet and very variable in the inter-row areas and wet and very stable in the corridors. Topsoil moisture in the areas with common sainfoin was much higher than in the rows (62–70%), whereas this difference was lower with spontaneous vegetation (40%). Two runoff and sediment traps (STs) were installed in two ephemeral gullies, and 26 time-integrated surveys (TIS) were done. The mean runoff yields were 9.8 and 13.5 L TIS−1 in ST2 and ST3. Rainfall depth (12 mm) and erosivity (5.2 MJ mm ha−1 h−1) thresholds for runoff initiation were assessed. The mean turbidity was 333 (ST2) and 19 (ST3) g L−1. Changes in the canopy covers (grapevines and vegetation covers), topography and rainfall parameters explained the runoff and sediment dynamics.

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A modelling study of the event-based retention performance of green roof under the hot-humid tropical climate in Kuching

Water Science & Technology ◽

10.2166/wst.2017.472 ◽

2017 ◽

Vol 76 (11) ◽

pp. 2988-2999 ◽

Cited By ~ 2

Author(s):

C. T. Chai ◽

F. J. Putuhena ◽

O. S. Selaman

Keyword(s):

Flash Flood ◽

Retention Rate ◽

Meteorological Data ◽

Green Roof ◽

Tropical Climate ◽

Climatic Conditions ◽

Retention Performance ◽

Strong Negative Correlation ◽

Rainfall Depth ◽

Event Based

Abstract The influences of climate on the retention capability of green roof have been widely discussed in existing literature. However, knowledge on how the retention capability of green roof is affected by the tropical climate is limited. This paper highlights the retention performance of the green roof situated in Kuching under hot-humid tropical climatic conditions. Using the green roof water balance modelling approach, this study simulated the hourly runoff generated from a virtual green roof from November 2012 to October 2013 based on past meteorological data. The result showed that the overall retention performance was satisfactory with a mean retention rate of 72.5% from 380 analysed rainfall events but reduced to 12.0% only for the events that potentially trigger the occurrence of flash flood. By performing the Spearman rank's correlation analysis, it was found that the rainfall depth and mean rainfall intensity, individually, had a strong negative correlation with event retention rate, suggesting that the retention rate increases with decreased rainfall depth. The expected direct relationship between retention rate and antecedent dry weather period was found to be event size dependent.

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