scholarly journals A Modified Distributed CN-VSA Method for Mapping of the Seasonally Variable Source Areas

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1270
Author(s):  
Kishore Panjabi ◽  
Ramesh Rudra ◽  
Pradeep Goel ◽  
Syed Ahmed ◽  
Bahram Gharabaghi
Keyword(s):  
Source Area ◽  
Moisture Distribution ◽  
Runoff Generation ◽  
Topographic Wetness Index ◽  
Runoff Simulation ◽  
Variable Source ◽  
Study Results ◽  
Potential Maximum ◽  
Scs Cn ◽  
Maximum Retention

Many watershed models employ the Soil Conservation Service Curve Number (SCS-CN) approach for runoff simulation based on soil and land use information. These models implicitly assume that runoff is generated by the Hortonian process and; therefore, cannot correctly account for the effects of topography, variable source area (VSA) and/or soil moisture distribution in a watershed. This paper presents a new distributed CN-VSA method that is based on the SCS-CN approach to estimate runoff amount and uses the topographic wetness index (TWI) to distribute the runoff-generating areas within the watershed spatially. The size of the saturated-watershed areas and their spatial locations are simulated by assuming an average annual value of potential maximum retention. However, the literature indicates significant seasonal variation in potential maximum retention which can considerably effect water balance and amount of nonpoint source pollution. This paper focuses on developing a modified distributed CN-VSA method that accounts for the seasonal changes in the potential maximum retention. The results indicate that the modified distributed CN-VSA approach is better than distributed CN-VSA to simulate runoff amount and spatial distribution of runoff-generating areas. Overall, the study results are significant for improved understanding of hydrological response of watershed where seasonal factors describe the potential maximum retention, and, thus, saturation excess runoff generation in the watershed.

scholarly journals Application of Risk Analysis in the Screening of Flood Disaster Hot Spots and Adaptation Strategies

Land ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Er-Chiang Huang ◽  
Pei-Wen Li ◽  
Shao-Wei Wu ◽  
Chao-Yuan Lin
Keyword(s):  
Surface Runoff ◽  
Flood Control ◽  
Land Development ◽  
Storage Space ◽  
Human Beings ◽  
Environmental Complexity ◽  
The Difference ◽  
Potential Maximum ◽  
Scs Cn ◽  
Maximum Retention

In recent years, Taiwan has established a sound flood control foundation in terms of river management. Due to climate change and land development, surface runoff has increased. In addition, the functions of flood control engineering facilities have their limits. Surface runoff cannot be fully absorbed by rivers, and frequent floods still occur in some areas. According to the characteristics of water flowing along the terrain to low-lying land, the terrain features can be used to find out the hot areas prone to flooding and the appropriate location of flood storage space for improving flooding. On the basis of the natural terrain environment, the disaster risk framework is used to manage environmental complexity, and to carry out research on flood warning and governance decision-making systems, so that human beings can coexist with the uncertainty of flood risk. In this study, the Zhuoshuixi Basin was used as the sample area, the SCS-CN method was used to analyze the excess runoff, and the risk concept was used to establish a flood evaluation model. In addition, through the changes in land use, the SCS-CN method estimates the difference of potential maximum retention, quantifies the variation of excess rainfall in each watershed division, and uses the digital elevation model to calculate the depression site to analyze the relationship between the difference of potential maximum retention and the depression space of the watershed. The results show that the adaptation strategy for high-risk flooded areas should be strengthened, and areas with large water storage space and a small potential maximum retention difference can be the best location for offsite compensation.

scholarly journals Effects of drainage treatment and stand growth on changes in runoff components from a forested watershed

2010 ◽  
Vol 56 (No. 7) ◽  
pp. 307-313
Author(s):  
V. Černohous ◽  
F. Šach ◽  
D. Kacálek
Keyword(s):  
Land Surface ◽  
Overland Flow ◽  
Source Area ◽  
Base Flow ◽  
Forested Watershed ◽  
Runoff Generation ◽  
Forest Environment ◽  
Variable Source ◽  
Positive Ratio ◽  
Long Time

Runoff generation under various natural conditions has often been studied in forested watersheds for a long time. In 1967, Hewlett designed a variable source area model. The model is based on the expansion and shrinkage of variable source areas and consequent changes in a drainage network during a discharge event. The runoff investigation was carried out in a forested watershed situated in the summit area of the Orlické hory Mts. The watershed has a drainage area of 32.6 ha with the land-surface elevation ranging from 880 to 940 m a.s.l. Runoff components, their amounts and ratios were calculated using a simple graphical-mathematical method of the hydrograph recession limb analysis according to a reservoir model representing the particular components (base flow, subsurface flow and overland flow, in other words slow, accelerated and rapid flows). Comparing the amount of slow and rapid runoff constituents (89.5–99.4% and 0.6–10.5%, respectively), the greater amount of slowly moving water confirmed that overland flow was absent under conditions of forest environment. Not even the drainage treatment altered this positive ratio of the runoff constituents. During the third period, under stabilized hydrology and stand conditions, the accelerated and rapid runoff increased again, however maximally by 10% and 4%, respectively, not reaching the initial size of the calibration period.

scholarly journals Impacts of climate change on runoff in the source area of the Yellow River

2021 ◽  
Author(s):  
Dongying Yi ◽  
Yue Xu ◽  
Nan Wang ◽  
Xiaoyi Ma
Keyword(s):  
General Circulation ◽  
Yellow River ◽  
Swat Model ◽  
Circulation Model ◽  
Source Area ◽  
Annual Runoff ◽  
The Yellow River ◽  
Runoff Simulation ◽  
Climate System Model ◽  
Average Annual Runoff

The primary approach to realizing long-term runoff prediction involves combining a hydrological model with general circulation model. Previous studies on the Source area of the Yellow River were all based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) data sets with defects in physical mechanisms. In this paper, the Beijing Climate Center Climate System Model (BCC-CSM2-MR) of CMIP6, which proved to perform well in arid and semi-arid regions, will be used to drive the Soil & Water Assessment Tool (SWAT) model and evaluate its applicability in runoff simulation at Tang Nahai Hydrological Station from 2011 to 2019. The occurrence of the extreme value of runoff, its change trend, and the year of abrupt change of runoff in the four Shared Socio-economic Pathway (SSP) scenarios (SSP1-2.6, 2-4.5, 3-7.0, and 5-8.5) during 2021-2100 were analyzed. The results show that: (1) the runoff simulation evaluation index of SWAT driven by BCC-CSM2-MR in the research area from 2011 to 2019 is excellent, and the runoff simulation in the future is reliable and effective. (2) only the average annual runoff in scenario 5-8.5 (708.5m /s) from 2021 to 2100 was significantly higher than that in 2011-2019. Other scenarios are close to or less than the annual runoff observed. Most importantly, the maximum and minimum annual runoff values under the four scenarios all occurred during 2060-2080, so the attribution analysis of runoff extremum during 2060-2080 is worth further study. (3) it is necessary to evaluate whether the existing reservoirs and hydropower stations in the Yellow River basin can reasonably regulate and utilize the annual runoff under scenario 5-8.5.

scholarly journals Identification of Surface Water Storing Sites Using Topographic Wetness Index (TWI) and Normalized Difference Vegetation Index (NDVI)

2018 ◽  
Vol 8 ◽  
pp. 91-100
Author(s):  
Belete Berhanu ◽  
Ethiopia Bisrat
Keyword(s):  
Surface Water ◽  
Water Resource ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Cost Effective ◽  
Water Shortage ◽  
Sample Volume ◽  
Runoff Generation ◽  
Topographic Wetness Index ◽  
Wetness Index

Ethiopia is endowed with water and has a high runoff generation area compared to many countries, but the total stored water only goes up to approximately 36BCM. The problem of water shortage in Ethiopia emanates from the seasonality of rainfall and the lack of infrastructure for storage to capture excess runoff during flood seasons. Based on this premise, a method for a syndicate use of topography, land use and vegetation was applied to locate potential surface water storing sites. The steady-state Topographic Wetness Index (TWI) was used to represent the spatial distribution of water flow and water stagnating across the study area and the Normalized Difference Vegetation Index (NDVI) was used to detect surface water through multispectral analysis. With this approach, a number of water storing sites were identified in three categories: primary sources (water bodies based), secondary sources (Swampy/wetland based) and tertiary sources (the land based). A sample volume analysis for the 120354 water storing sites in category two, gives a 44.92BCM potential storing capacity with average depth of 4 m that improves the annual storage capacity of the country to 81BCM (8.6 % of annual renewable water sources). Finally, the research confirmed the TWI and NDVI based approach for water storing sites works without huge and complicated earth work; it is cost effective and has the potential of solving complex water resource challenges through spatial representation of water resource systems. Furthermore, the application of remote sensing captures temporal diversity and includes repetitive archives of data, enabling the monitoring of areas, even those that are inaccessible, at regular intervals.

A GIS-based variable source area hydrology model

1999 ◽  
Vol 13 (6) ◽  
pp. 805-822 ◽  
Author(s):  
Jane R. Frankenberger ◽  
Erin S. Brooks ◽  
M. Todd Walter ◽  
Michael F. Walter ◽  
Tammo S. Steenhuis
Keyword(s):  
Source Area ◽  
Variable Source ◽  
Variable Source Area ◽  
Hydrology Model

Application of SWAT with and without Variable Source Area Hydrology to a Large Watershed

2013 ◽  
Vol 50 (1) ◽  
pp. 42-56 ◽  
Author(s):  
Joshua D. Woodbury ◽  
Christine A. Shoemaker ◽  
Zachary M. Easton ◽  
Dillon M. Cowan
Keyword(s):  
Source Area ◽  
Variable Source ◽  
Variable Source Area
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