scholarly journals Regionalization of coaxial correlation diagrams for the semi-humid and semi-arid catchments in Northern China

2015 ◽  
Vol 368 ◽  
pp. 317-322 ◽  
Author(s):  
Q. Li ◽  
Z. Li ◽  
L. Chen ◽  
C. Yao
Keyword(s):  
Land Cover ◽  
Soil Type ◽  
Euclidean Distance ◽  
Arid Regions ◽  
Northern China ◽  
Correlation Diagram ◽  
Ungauged Catchments ◽  
Physical Similarity ◽  
Runoff Prediction ◽  
Semi Arid

Abstract. This study aims to identify both hydrologically and physically similar catchments which would be the best donors for runoff prediction in ungauged catchments. For this study, eight gauged catchments located in the semi-humid and semi-arid regions of Northern China were used. Hydrological similarity was defined based on the transferability of coaxial correlation diagrams. The physical similarity among catchments was determined by a weighted Euclidean distance based on 19 catchment descriptors including catchment topography, land cover, and soil type. The overlap between hydrologically similar catchments and physically similar catchments was then analysed to identify the best donors. The results suggest that six catchments were hydrologically similar, of which four catchments were both hydrologically and physically similar. It is argued that once a reliable coaxial correlation diagram has been established, the coaxial correlation diagram can be transferred from one catchment to another for runoff prediction, provided that these catchments are physical similar.

Mapping of land cover in semi-arid regions based on a multi-gate semi-supervised learning method – a case study of Zhangbei, China

2021 ◽  
Vol 13 (2) ◽  
pp. 207-217
Author(s):  
Boan Chen ◽  
Quanlong Feng ◽  
Bowen Niu ◽  
Jianyu Yang ◽  
Bingbo Gao ◽  
...  
Keyword(s):  
Land Cover ◽  
Supervised Learning ◽  
Arid Regions ◽  
Learning Method ◽  
Semi Arid

scholarly journals Bivariate Based Susceptibility Mapping for Gully Erosion in Wanjoga River Catchment Upper Tana Basin, Kenya

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Cecilia Wawira Ireri ◽  
George Krhoda ◽  
Mukhovi Stellah
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Arid Regions ◽  
Rainfall Variability ◽  
Gully Erosion ◽  
Geographical Information ◽  
Susceptibility Map ◽  
Error Matrix ◽  
Conditioning Factors ◽  
Semi Arid

Gullies occur in semi-arid regions characterized by rainfall variability and seasonality, increased overland flow, affecting ecological fragility of an area. In most gully prone areas, extent of land affected by gullies is increasing. Thus, predicting susceptibility to gully erosion in semi-arid environment is an important step towards effectively rehabilitating and prevention against gully erosion. Proneness to gully occurrence was assessed against; Land cover/land use, slope, soil characteristics, rainfall variability and elevation, and modelled using geographical information system (GIS)-based bivariate statistical approach. Objectives of the study were; a) to assess influence of geomorphological factors on gully erosion, b) analyze and develop gully erosion susceptibility map, c) verify gully susceptibility images using error matrix of class labels in classified map against ground truth reference data. Total of 66 gullied areas (width and depth ≥ ranging 0.5), were mapped using 15m resolution Landsat images for 2018 and field surveys to estimate susceptibility to gully erosion by Global Mapper software in GIS. The images were verified using 120 pixels of known 15 gully presence or absence to produce an error matrix based on comparison of actual outcomes to predicted outcomes. Influence of conditioning factors to gully erosion showed a significant positive relationship between gully susceptibility and gully conditioning factors with consistency value; CR =0.097; value< 0.1, indicating, individual conditioning factors had an importance in influencing gully erosion. Slope (43%) and soil lithotype (25%), most influenced gully susceptibility, while land cover/land use (12%) and rainfall (12%) had least impact. Verification results showed satisfactory agreement between susceptibility map and field data on gullied areas at approximately 76.2%, an error of positive value of 4% and a negative value of 7%. Thus, production of susceptibility map by bivariate statistical method represents a useful tool for ending long and short-term gully emergencies by planning conservation of semi-arid regions.

scholarly journals Runoff prediction in ungauged catchments in Norway: comparison of regionalization approaches

2017 ◽  
Vol 49 (2) ◽  
pp. 487-505 ◽  
Author(s):  
Xue Yang ◽  
Jan Magnusson ◽  
Jonathan Rizzi ◽  
Chong-Yu Xu
Keyword(s):  
International Association ◽  
Balance Model ◽  
Spatial Proximity ◽  
Ungauged Catchments ◽  
Theoretical Understanding ◽  
Study Region ◽  
Physical Similarity ◽  
Homogeneous Groups ◽  
Stream Flows ◽  
Runoff Prediction

Abstract Runoff prediction in ungauged catchments has been a challenging topic over recent decades. Much research have been conducted including the intensive studies of the PUB (Prediction in Ungauged Basins) Decade of the International Association for Hydrological Science. Great progress has been made in the field of regionalization study of hydrological models; however, there is no clear conclusion yet about the applicability of various methods in different regions and for different models. This study made a comprehensive assessment of the strengths and limitations of existing regionalization methods in predicting ungauged stream flows in the high latitudes, large climate and geographically diverse, seasonally snow-covered mountainous catchments of Norway. The regionalization methods were evaluated using the water balance model – WASMOD (Water And Snow balance MODeling system) on 118 independent catchments in Norway, and the results show that: (1) distance-based similarity approaches (spatial proximity, physical similarity) performed better than regression-based approaches; (2) one of the combination approaches (combining spatial proximity and physical similarity methods) could slightly improve the simulation; and (3) classifying the catchments into homogeneous groups did not improve the simulations in ungauged catchments in our study region. This study contributes to the theoretical understanding and development of regionalization methods.

scholarly journals Analysis of urban heat island characteristics and mitigation strategies for eight arid and semi-arid gulf region cities

2021 ◽  
Vol 80 (7) ◽  
Author(s):  
Ammar Abulibdeh
Keyword(s):  
Land Cover ◽  
Urban Areas ◽  
Arid Regions ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Gulf Region ◽  
Green Areas ◽  
Urban Heat ◽  
The Difference ◽  
Semi Arid

AbstractThe aim of the study is, therefore, to analyze the formation of the UHIs in eight different cities in arid and semi-arid regions. The analysis is based on land cover (LC) classification (urban, green, and bare areas). The study found that bare areas had the highest mean LST values compared to the urban and green areas. The results show that the difference in temperatures between the bare areas and the urban areas ranges between 1 and 2 °C, between the bare areas and green areas ranges between 1 and 7 °C, and between the urban areas and green areas ranges between 1 and 5 °C. Furthermore, the LST values varied for each of the LULC categories, and hence some areas in the three categories had lower or higher LST values than in other categories. Hence, one category may not always have the highest LST value compared to other categories. The outcomes of this study may, therefore, have critical implications for urban planners who seek to mitigate UHI effects in arid and semi-arid urban areas.

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