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Spatial mapping and testing the applicability of the curve number method for ungauged catchments in Northern Ethiopia

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International Soil and Water Conservation Research 2017年第4期5卷 293-301页

作者： Demlie Gebresellassie Zelelew Amhara Agricultural Research Institute Sirinka Agricultural Research CentreP.O.Box74North WolloWoldiaEthiopia

Understanding the spatial variability of land and water resources has significant importance for its planning,management,and *** is also significant in understanding the response behavior of a catchment in order to model the basic physical *** this study,a weighted overlay analysis technique using ArcGIS was implemented for developing a geo-database of the standard curve number(SCN)in a catchment around Northern *** spatial data were used to investigate a'standard curve number method'for the simulation of the direct runoff at the outlet of the *** spot based rainfall and runoff measuring techniques were adopted for deriving an instant observed flow measurement,and to make a comparison with the simulated flow *** results showed that the model underestimated most of the simulated values with a coefficient of regression of R^(2)=0.52,with a proportion of higher variances between the simulated and observed runoff *** result suggests that the accuracy of the model leaves room for significant improvement and the method could not be easily adopted in the catchment and other similar catchments in the semi arid regions of *** improving the prediction capacity of the model,further research in adjusting loss factors in the method is *** is also suggested for developing a localized and modified SCN values by considering geologic,climatic and seasonal *** results of this study and the maps generated can be used for improving the hydrological understanding of the *** study is useful for further investigation of the SCN methodology in other un-gauged catchments around the world.

关键词： Ungauged Spatial database curve number Runoff,GIS

Comparison of Three Delineation Methods Using the curve number Method to Model Runoff

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Journal of Water Resource and Protection 2016年第11期8卷 945-964页

作者： William D. Troolin Katherine Clancy College of Natural Resources University of Wisconsin-Stevens Point Stevens Point USA

Digital Elevation Models (DEMs) are spatial grids which are used to automate watershed boundary determination. Sinks are present within most DEMs. In order to easily process the watershed boundary, the sinks are reassigned to elevation equivalent to an adjacent cell. The derived DEM is called a “filled” DEM. Due to its relative simplicity, the use of the “filled” DEM is one of the most widely used methods to delineate watershed boundaries and works well in about 70 percent of the watersheds in the US. In landscapes with internal drainage, sinks may accurately represent these depressions. In this study, we compare two delineation methods that do not fill in sinks to another method that does fill in sinks. We examined ten gaged watersheds in Wisconsin and Minnesota. We found the spatial extent of the watersheds from the three methods were significantly different. To evaluate the delineation methods, we modeled ten runoff events using the curve number (CN) method and compared them to USGS gage discharge for each watershed. For small storms we found that there were no significant differences in the modeled runoff for three delineation methods. For large storms, we found the no-fill methods had a smaller error, but overall the difference was insignificant. This research suggests that capturing internal drainage by the delineation does not have much of an impact on the widely used CN model.

关键词： Geographic Information Systems Runoff Watershed Management curve number

Application of the SCS-CN Model to Runoff Estimation in a Small Watershed with High Spatial Heterogeneity

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Pedosphere 2011年第6期21卷 738-749页

作者： XIAO Bo WANG Qing-Hai FAN Jun HAN Feng-Peng DAI Quan-Hou Beijing Research ＆ Development Center for Grass and Environment Beijing Academy of Agriculture and Forestry Sciences Beijing 100097 （China） State Key Laboratory of Soil Erosion and Dryland Farmning on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling 712100 （China） Colleqe of Forest Guizhou University Guiyang 550025 （China）

For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service curve number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated and the most appropriate initial abstraction ratio （I~/S） value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S value when one heavy rainfall event （50.1 mm） was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.

关键词： curve number initial abstraction ratio model performance rainfall soil and water loss

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Effects of urbanization on groundwater level in aquifers of Binh Duong Province,Vietnam

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Journal of Groundwater Science and Engineering 2021年第1期9卷 20-36页

作者： Luong Van Viet Institute for Environmental Science Engineering and ManagementIndustrial University of Ho Chi Minh CityHo Chi Minh CityVietnam

The purpose of this paper was to assess the impact of urbanization on the groundwater level(GWL)in aquifers of Binh Duong(BD)*** research method is to analyze the trend of GWL,the recharge capacity of surface over time and the relationship between *** data of the GWL used in the study are the average values in the dry and rainy seasons of 35 observation wells from 2011 to 2018,which are in Pleistocene and Pliocene *** ability to recharge groundwater from the surface in this study was represented by the curve number(CN),a parameter used in hydrology for calculating direct runoff or infiltration from *** land use data to identify the CN was analyzed from the Landsat *** results show that besides over-exploitation,the change of surface characteristic due to the urbanization development process is also the cause of the GWL *** analysis of seasonal GWL data shows that the increase in impervious surface area is the cause of GWL decline in the Pleistocene aquifer,which is more evident in the rainy season than in the dry *** statistical results also show that in the rainy season and in shallow aquifers,a higher CN change can be found with the wells that had a remarkable GWL decline compared to the remaining wells.

关键词： Urbanization Land use change Impervious surface curve number Groundwater level

RUNOFF-ENERGY FACTORS FORMUSLE SEDIMENT-YIELD MODEL FOR SURFACE MINES

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International Journal of Sediment Research 2000年第2期 162-181页

作者： James V. Bonta(Research Hydraulic Engineer, USDA-Agriculture Research Service, North Appalachian Experimental Watershed,P.O. Box 488, Coshocton, OH 43812. email:bonta@*** )

The Modified Universal Soil Loss Equation (MUSLE) is often used for sediment-yield estimations insurface mines for design and impact evaluations. However, it is not known if the widely-used runoff-energy factor of MUSLE is appropriate, or if its parameters are the same for surface mines as foragricultural watersheds from which MUSLE was developed. Suspended-sediment data from threeexperimental watersheds in Ohio (approximately 1O - 2O ha), subjected to near complete distUrbance dueto mining and reclamation, were used to investigate five altemate runoffenergy factors in the MUSLEsediment-yield model for use in surface mines. The evaluation led to the selection of the generalizedmodel form, a (runoff volume X peak flow rate)b, as the best choice among models *** b was greater than the widely-used value of 0.56, ranging from 0.68 to 1. 10. Parameter b wasdependent on whether mining-or reclamation-related watershed activities were predominam. Theoriginal Williams (1975) model fit the data least well of the five energy factors studied.

关键词： MUSLE USLE Surface mine Hydrology Sedimentation Sediment yield Erosion Drastic land disturbance Disturbed land curve number Water quality

Economic valuation of water storage function of forest ecosystems (case study: Zagros Forests, Iran)

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Journal of Forestry Research 2010年第3期21卷 293-300,396,397页

作者： Zahra Mashayekhi Mostafa Panahi Mahmoud Karami Shahram Khalighi Arash Malekian Natural Resources Faculty University of Tehran Islamic Azad University

Forest ecosystem services contribute to human welfare, both directly and indirectly. Here the economic value of water conservation by Bazoft basin located in Zagros forests in western Iran was estimated, using simulation models and Geographic Information System （GIS） as a tool for analyzing the effects of ecological factors on ecosystem services. Rainfall-runoff simulation was carried out by using curve number （CN） method in HEC-HMS model. The model requires the inputs of land cover, soil and short term rainfall and discharge data. The efficiency of simu-lated model was revised using observed data and doing calibration stages. The role of forest on water retention and surface runoff reduction by devising four hypothetical scenarios and then the effects of land use changes associated with these scenarios on rainfall-runoff behavior of the region were determined. The results show that under the case of scenario one which assumes that the entire of basin area is covered by forests, total outflow would be in the minimum amount and rainfall initial loss will increase. Forest hydrological services related to water retention was economically assessed using Replacement Cost Method. Valuation results show that each hectare of Bazoft forests can store 84.8 m3 water with 0.5 US$/m3 annual value. So the water retention value of each hectare of these forests will be 43US$. This could have positive economic consequences for the region and would help decision-makers in selecting appropriate and economically feasible development strategies.

关键词： Bazoft River basin curve number economic valuation replacement cost runoff

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Evaluating the Effect of Land Cover, Seasonality and Delineation Method on Runoff at the Watershed Scale

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Journal of Water Resource and Protection 2021年第9期13卷 750-765页

作者： Katherine Clancy College of Natural Resources University of Wisconsin-Stevens Point Stevens Point WI USA

The aim of this study was to determine if runoff estimates from the curve number model were affected by seasons for different land covers. Eighteen watersheds with varying land covers were delineated using three methods. The delineation methods differ in how internal drainage is evaluated. Runoff estimates from storms for spring, summer, and fall were compared to observed runoff from USGS gaging station data. Errors (difference between estimate runoff and observed runoff) were found to be highest for fall by 3% for all the two delineation methods which do not consider internal drainage. Watersheds were categorized by their dominant land cover (agriculture, forest, or urban). Seasonal differences were found to be significant for certain land covers. The greatest differences between observed and estimated data were found in agriculture and urban especially spring versus fall for all delineations. Forest land cover was found to have no seasonal difference for all three delineation methods. The research suggests that this work contributes to the growing body of research suggesting that vegetative seasonal differences have a greater impact on runoff than is accounted for in the runoff model.

关键词： Runoff curve number Vegetation Seasonal