Runoff generation from successive simulated rainfalls on a rocky, semi-arid, Mediterranean hillslope

2003 ◽  
Vol 17 (2) ◽  
pp. 279-296 ◽  
Author(s):  
J. Lange ◽  
N. Greenbaum ◽  
S. Husary ◽  
M. Ghanem ◽  
C. Leibundgut ◽  
...  
Keyword(s):  
Runoff Generation ◽  
Semi Arid

scholarly journals Evaluation of coupled ANN-GA model to prioritize flood source areas in ungauged watersheds

2020 ◽  
Vol 51 (3) ◽  
pp. 423-442
Author(s):  
Naser Dehghanian ◽  
S. Saeid Mousavi Nadoushani ◽  
Bahram Saghafian ◽  
Morteza Rayati Damavandi
Keyword(s):  
Flood Control ◽  
Mean Squared Error ◽  
Absolute Error ◽  
Ann Model ◽  
Runoff Generation ◽  
Source Areas ◽  
Walnut Gulch ◽  
Artificial Neural Network Ann ◽  
Semi Arid ◽  
Flood Source

Abstract An important step in flood control planning is identification of flood source areas (FSAs). This study presents a methodology for identifying FSAs. Unit flood response (UFR) approach has been proposed to quantify FSAs at subwatershed and/or cell scale. In this study, a distributed ModClark model linked with Muskingum flow routing was used for hydrological simulations. Furthermore, a fuzzy hybrid clustering method was adopted to identify hydrological homogenous regions (HHRs) resulting in clusters involving the most effective variables in runoff generation as selected through factor analysis (FA). The selected variables along with 50-year rainfall were entered into an artificial neural network (ANN) model optimized via genetic algorithm (GA) to predict flood index (FI) at cell scale. The case studies were two semi-arid watersheds, Tangrah in northeastern Iran and Walnut Gulch Experimental Watershed in Arizona. The results revealed that the predicted values of FI via ANN-GA were slightly different from those derived via UFR in terms of mean squared error (MSE), mean absolute error (MAE), and relative error (RE). Also, the prioritized FSAs via ANN-GA were almost similar to those of UFR. The proposed methodology may be applicable in prioritization of HHRs with respect to flood generation in ungauged semi-arid watersheds.

Processes of runoff generation operating during the spring and autumn seasons in a permafrost catchment on semi-arid plateaus

2017 ◽  
Vol 550 ◽  
pp. 307-317 ◽  
Author(s):  
Wang Genxu ◽  
Mao Tianxu ◽  
Chang Juan ◽  
Song Chunlin ◽  
Huang Kewei
Keyword(s):  
Runoff Generation ◽  
Semi Arid

scholarly journals A Flexible Framework HydroInformatic Modeling System—HIMS

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 962 ◽  
Author(s):  
Lili Wang ◽  
Zhonggen Wang ◽  
Changming Liu ◽  
Peng Bai ◽  
Xiaocong Liu
Keyword(s):  
Assessment Tool ◽  
Swat Model ◽  
Model Performance ◽  
Arid Areas ◽  
Hydrological Models ◽  
Runoff Generation ◽  
Infiltration Capacity ◽  
Water Cycling ◽  
Generation Mechanisms ◽  
Semi Arid

It is important to simulate streamflow with hydrological models suitable for the particular study areas, as the hydrological characteristics of water cycling processes are distinctively different due to spatial heterogeneity at the watershed scale. However, most existing hydrological models cannot be customized to simulate water cycling processes of different areas due to their fixed structures and modes. This study developed a HydroInformatic Modeling System (HIMS) model with a flexible structure which had multiple equations available to describe each of the key hydrological processes. The performance of the HIMS model was evaluated with the recommended structure for semi-arid areas by comparisons with two datasets of observed streamflow: the first one of 53 Australian watersheds, the second one of the Lhasa River basin in China. Based on the first dataset, the most appropriate watersheds were identified for the HIMS model utilization with areas of 400–600 km2 and annual precipitation of 800–1200 mm. Based on the second dataset, the model performance was statistically satisfied with Nash-Sutcliffe Efficient (NSE) greater than 0.87 and Water Error (WE) within ±20% on the streamflow simulation at hourly, daily, and monthly time steps. In addition, the water balance was mostly closed with respect to precipitation, streamflow, actual evapotranspiration (ET), and soil moisture change at the annual time steps in both the periods of calibration and validation. Therefore, the HIMS model was reliable in estimating streamflow and simulating the water cycling processes for the structure of semi-arid areas. The simulated streamflow of HIMS was compared with those of the Variable Infiltration Capacity model (VIC) and Soil and Water Assessment Tool (SWAT) models and we found that the HIMS model performed better than the SWAT model, and had similar results to the VIC model with combined runoff generation mechanisms.

Effect of temporal rainfall distribution and soil type on soil moisture and runoff generation in semi-arid Zimbabwe

2007 ◽  
Vol 38 (3) ◽  
pp. 249-263 ◽  
Author(s):  
F.T. Mugabe ◽  
M.G. Hodnett ◽  
A. Senzanje
Keyword(s):  
Soil Moisture ◽  
Overland Flow ◽  
Daily Rainfall ◽  
Soil Surface ◽  
Runoff Generation ◽  
Stream Channels ◽  
Wet Season ◽  
Sodic Soils ◽  
Rainfall Distribution ◽  
Semi Arid

This paper examines the effect of temporal rainfall distribution on soil moisture and runoff generation in the 5.9 km2 Mutangi catchment in semi-arid Zimbabwe. Rainfall, soil moisture and runoff were measured during the 1999/00 and 2000/01 rainy seasons during which periods 755 mm and 615 mm of rainfall were received, respectively. The percentage of rainfall totals in these periods were 58% and 69%, respectively, in February. The total catchment runoff was 102 mm and 63 mm, of which 52% and 49% were recorded over 6 and 4 d in 2000 and 2001, respectively. Baseflow was negligible. Rainfall intensities were generally low. In the 1999/00 season there were 2 and 8 h with intensities >20 mm h−1 and 10 mm h−1, respectively. Some runoff appears to be generated by Hortonian overland flow (HOF), mainly in the early wet season before ploughing creates a rougher soil surface. The dominant process of runoff in this catchment was saturated overland flow (SOF), which occurs when the soils become saturated from below. The sodic soils along the stream channels appear to generate most of the runoff because of their small capacity to store water before saturation. The ridge soils are coarse sands, with a large capacity to store rainfall. The transitional (slope) soils have an intermediate capacity to store water. If there is a sequence of daily events that completely fills the storage available in both the sodic and transitional soils, and which begins to saturate the ridge soils, there could be very large amounts of runoff (>50% of the daily rainfall). The occurrence of such runoff events depends very heavily on the distribution of rainfall. Dry spells between rain events create storage, thereby reducing the risk of runoff from the next events.

scholarly journals Understanding runoff processes in a semi-arid environment through isotope and hydrochemical hydrograph separations

2015 ◽  
Vol 19 (10) ◽  
pp. 4183-4199 ◽  
Author(s):  
V. V. Camacho Suarez ◽  
A. M. L. Saraiva Okello ◽  
J. W. Wenninger ◽  
S. Uhlenbrook
Keyword(s):  
Surface Water ◽  
Overland Flow ◽  
Hydrological Process ◽  
Arid Areas ◽  
Runoff Generation ◽  
Deep Groundwater ◽  
Direct Runoff ◽  
Total Runoff ◽  
Semi Arid

Abstract. The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs may increase the complexity of hydrological process dynamics. Isotope and hydrochemical tracers have proven to be useful in identifying runoff components and their characteristics. Moreover, although widely used in humid temperate regions, isotope hydrograph separations have not been studied in detail in arid and semi-arid areas. Thus the purpose of this study is to determine whether isotope hydrograph separations are suitable for the quantification and characterization of runoff components in a semi-arid catchment considering the hydrological complexities of these regions. Through a hydrochemical characterization of the surface water and groundwater sources of the catchment and two- and three-component hydrograph separations, runoff components of the Kaap catchment in South Africa were quantified using both isotope and hydrochemical tracers. No major disadvantages while using isotope tracers over hydrochemical tracers were found. Hydrograph separation results showed that runoff in the Kaap catchment is mainly generated by groundwater sources. Two-component hydrograph separations revealed groundwater contributions of between 64 and 98 % of total runoff. By means of three-component hydrograph separations, runoff components were further separated into direct runoff, shallow and deep groundwater components. Direct runoff, defined as the direct precipitation on the stream channel and overland flow, contributed up to 41 % of total runoff during wet catchment conditions. Shallow groundwater defined as the soil water and near-surface water component (and potentially surface runoff) contributed up to 45 % of total runoff, and deep groundwater contributed up to 84 % of total runoff. A strong correlation for the four studied events was found between the antecedent precipitation conditions and direct runoff. These findings suggest that direct runoff is enhanced by wetter conditions in the catchment that trigger saturation excess overland flow as observed in the hydrograph separations.

scholarly journals Comparing the Hydrological Response of Forested Headwaters (Unregulated and Regulated with Check Dams) under Mediterranean Semi-Arid Conditions

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1275
Author(s):  
Giuseppe Bombino ◽  
Pedro Pérez-Cutillas ◽  
Daniela D’Agostino ◽  
Pietro Denisi ◽  
Antonino Labate ◽  
...  
Keyword(s):  
Soil Loss ◽  
Forest Cover ◽  
Catchment Management ◽  
Runoff Generation ◽  
Sediment Retention ◽  
Retention Capacity ◽  
Erosion Rates ◽  
Check Dams ◽  
Generation Capacity ◽  
Semi Arid

This study has evaluated the runoff and erosion rates in torrents of Southern Italy, two forested headwaters with very similar climatic, hydrological and geomorphological characteristics; in one headwater, 15 check dams were installed in the mid-1950s, while the other is not regulated with engineering works. To this aim, the hydrological variables have been modeled over 15 years after check dam installation using the HEC-HMS (Hydrologic Engineering Center-Hydrologic Modeling System) model coupled to the MUSLE (Modified Universal Soil Loss Equation) equation. The model simulations have shown that check dams have not played a significant role in reducing the surface runoff compared to the unregulated torrent; in both catchments, the well-developed forest cover determined very low runoff coefficients (lower than 0.3%) with a scarce runoff generation capacity. Additionally, the reduction in peak flow due to the check dams was not significant, on average −7.4% compared to the unregulated headwater. Check dams have retained sediments for about 8–10 years after their installation, reducing erosion by about 35%, although soil loss was much lower than the tolerance limit in both catchments. After the sediment retention capacity of the dam sediment wedge was depleted, the sediment yield in the regulated torrent was even higher (by about 20%) compared to the unregulated catchment. Overall, the study has shown that the use of check dams as a catchment management strategy of forested headwaters under semi-arid Mediterranean conditions should be considered with caution, since the structures could be ineffective to reduce water and sediment flows during floods or, in some cases, check dams may increase erosion rates.

scholarly journals Understanding runoff processes in a semi-arid environment through isotope and hydrochemical hydrograph separations

2015 ◽  
Vol 12 (1) ◽  
pp. 975-1015 ◽  
Author(s):  
V. V. Camacho ◽  
A. M. L Saraiva Okello ◽  
J. W. Wenninger ◽  
S. Uhlenbrook
Keyword(s):  
Surface Water ◽  
Overland Flow ◽  
Hydrological Process ◽  
Arid Areas ◽  
Runoff Generation ◽  
Deep Groundwater ◽  
Direct Runoff ◽  
Total Runoff ◽  
Semi Arid

Abstract. The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs increase the complexity of hydrological process dynamics. Isotope and hydrochemical tracers have proven to be useful in identifying runoff components and their characteristics. Moreover, although widely used in humid-temperate regions, isotope hydrograph separations have not been studied in detail in arid and semi-arid areas. Thus the purpose of this study is to determine if isotope hydrograph separations are suitable for the quantification and characterization of runoff components in a semi-arid catchment considering the hydrological complexities of these regions. Through a hydrochemical characterization of the surface water and groundwater sources of the catchment and two and three component hydrograph separations, runoff components of the Kaap Catchment in South Africa were quantified using both, isotope and hydrochemical tracers. No major disadvantages while using isotope tracers over hydrochemical tracers were found. Hydrograph separation results showed that runoff in the Kaap catchment is mainly generated by groundwater sources. Two-component hydrograph separations revealed groundwater contributions between 64 and 98% of total runoff. By means of three-component hydrograph separations, runoff components were further separated into direct runoff, shallow and deep groundwater components. Direct runoff, defined as the direct precipitation on the stream channel and overland flow, contributed up to 41% of total runoff during wet catchment conditions. Shallow groundwater defined as the soil water and near-surface water component, contributed up to 45% of total runoff, and deep groundwater contributed up to 84% of total runoff. A strong correlation for the four studied events was found between the antecedent precipitation conditions and direct runoff. These findings suggest that direct runoff is enhanced by wetter conditions in the catchment which trigger saturation excess overland flow as observed in the hydrograph separations.

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